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Sample records for pulsar psr j1028-5819

  1. VLT Suzaku observations of the Fermi pulsar PSR J1028-5819

    CERN Document Server

    Mignani, R P; Esposito, P; De Luca, A; Marelli, M; Oates, S R; Saz-Parkinson, P

    2012-01-01

    We used optical images taken with the Very Large Telescope (VLT) in the B and V bands to search for the optical counterpart of PSR J1028-5819 or constrain its optical brightness. At the same time, we used an archival Suzaku observation to confirm the preliminary identification of the pulsar's X-ray counterpart obtained by Swift. Due to the large uncertainty on the pulsar's radio position and the presence of a bright (V = 13.2) early F-type star at < 4", we could not detect its counterpart down to flux limits of B~25.4 and V ~25.3, the deepest obtained so far for PSR J1028-5819. From the Suzaku observations, we found that the X-ray spectrum of the pulsar's candidate counterpart is best-fit by a power-law with spectral index 1.7 +/- 0.2 and an absorption column density NH < 10^21 cm-2, which would support the proposed X-ray identification. Moreover, we found possible evidence for the presence of diffuse emission around the pulsar. If real, and associated with a pulsar wind nebula (PWN), its surface bright...

  2. Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Atwood, W.B.; /UC, Santa Cruz; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Baring, Matthew G.; /Rice U.; Bastieri, Denis; /INFN, Padua /Padua U.; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, Elliott D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle; Caliandro, G.A.; /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /George Mason U. /Naval Research Lab, Wash., D.C. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Montpellier U. /Sonoma State U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /Stockholm U. /Naval Research Lab, Wash., D.C. /INFN, Trieste /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /NASA, Goddard /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Montpellier U. /Bari U. /INFN, Bari /Ecole Polytechnique /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Trieste /Hiroshima U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; /more authors..

    2009-05-15

    Radio pulsar PSR J1028-5819 was recently discovered in a high-frequency search (at 3.1 GHz) in the error circle of the Energetic Gamma-Ray Experiment Telescope (EGRET) source 3EG J1027-5817. The spin-down power of this young pulsar is great enough to make it very likely the counterpart for the EGRET source. We report here the discovery of {gamma}-ray pulsations from PSR J1028-5819 in early observations by the Large Area Telescope (LAT) on the Fermi Gamma-Ray Space Telescope. The {gamma}-ray light curve shows two sharp peaks having phase separation of 0.460 {+-} 0.004, trailing the very narrow radio pulse by 0.200 {+-} 0.003 in phase, very similar to that of other known {gamma}-ray pulsars. The measured {gamma}-ray flux gives an efficiency for the pulsar of {approx}10-20% (for outer magnetosphere beam models). No evidence of a surrounding pulsar wind nebula is seen in the current Fermi data but limits on associated emission are weak because the source lies in a crowded region with high background emission. However, the improved angular resolution afforded by the LAT enables the disentanglement of the previous COS-B and EGRET source detections into at least two distinct sources, one of which is now identified as PSR J1028-5819.

  3. Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope

    CERN Document Server

    2009-01-01

    Radio pulsar PSR J1028-5819 was recently discovered in a high-frequency search (at 3.1 GHz)in the error circle of the EGRET source 3EG J1027-5817. The spin-down power of this young pulsar is great enough to make it very likely the counterpart for the EGRET source. We report here the discovery of gamma-ray pulsations from PSR J1028-5819 in early observations by the Large Area Telescope (LAT) on the Fermi Gamma-Ray Space Telescope. The gamma-ray light curve shows two sharp peaks having phase separation of 0.460 +- 0.004, trailing the very narrow radio pulse by 0.200 +- 0.003 in phase, very similar to that of other known $\\gamma$-ray pulsars. The measured gamma-ray flux gives an efficiency for the pulsar of 10-20% (for outer magnetosphere beam models). No evidence of a surrounding pulsar wind nebula is seen in the current Fermi data but limits on associated emission are weak because the source lies in a crowded region with high background emission. However, the improved angular resolution afforded by the LAT ena...

  4. SQM stars around pulsar PSR B1257+12

    CERN Document Server

    Kutschera, Marek; Kubis, Sebastian; Bratek, Łukasz

    2010-01-01

    Following Wolszczan's landmark discovery of planets in orbit around pulsar PSR B1257+12 in 1991, over 300 planets in more than 200 planetary systems have been found. Therefore, the meaning of Wolszczan's discovery cannot be overestimated. In this paper we aim to convince the reader that the objects accompanying pulsar PSR B1257+12 are more exotic than thought so far. They might not be ordinary planets but dwarf strange quark stars, whereas the pulsar might be a quark star with standard mass, not a neutron star. If this was the case, it would indicate that strange quark matter is the ground state of matter.

  5. On the nature of the intermittent pulsar PSR B1931+24

    NARCIS (Netherlands)

    Rea, N.; Kramer, M.; Stella, L.; Bassa, C. G.; Groot, P. J.; Israel, G. L.; Mendez, M.; Possenti, A.; Lyne, A.; Jonker, P.G.

    2008-01-01

    PSR B1931+24 is the first intermittent radio pulsar discovered to date, characterized by a 0.8-s pulsation, which turns on and off quasi-periodically every similar to 35 d, with a duty cycle of similar to 10 per cent. Here, we present X-ray and optical observations of PSR B1931+24 performed with the

  6. Optical counterparts of two Fermi millisecond pulsars: PSR J1301+0833 and PSR J1628–3205

    Energy Technology Data Exchange (ETDEWEB)

    Li, Miao; Halpern, Jules P. [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Thorstensen, John R., E-mail: miao@astro.columbia.edu [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States)

    2014-11-10

    Using the 1.3 m and 2.4 m Telescopes of the MDM Observatory, we identified the close companions of two eclipsing millisecond radio pulsars that were discovered by the Green Bank Telescope in searches of Fermi Gamma-ray Space Telescope sources, and measured their light curves. PSR J1301+0833 is a black widow pulsar in a 6.5 hr orbit whose companion star is strongly heated on the side facing the pulsar. It varies from R = 21.8 to R > 24 around the orbit. PSR J1628–3205 is a 'redback', a nearly Roche-lobe-filling system in a 5.0 hr orbit whose optical modulation in the range 19.0 < R < 19.4 is dominated by strong ellipsoidal variations, indicating a large orbital inclination angle. PSR J1628–3205 also shows evidence for a long-term variation of about 0.2 mag, and an asymmetric temperature distribution possibly due to either off-center heating by the pulsar wind, or large starspots. Modeling of its light curve restricts the inclination angle to i > 55°, the mass of the companion to 0.16 < M{sub c} < 0.30 M {sub ☉}, and the effective temperature to 3560 < T {sub eff} < 4670 K. As is the case for several redbacks, the companion of PSR J1628–3205 is less dense and hotter than a main-sequence star of the same mass.

  7. X-ray Studies of the Black Widow Pulsar PSR B1957+20

    OpenAIRE

    Huang, RHH; Kong, AKH; Takata, J; Hui, CY; Lin, LCC; Cheng, KS

    2012-01-01

    We report on Chandra observations of the black widow pulsar, PSR B1957+20. Evidence for a binary-phase dependence of the X-ray emission from the pulsar is found with a deep observation. The binary-phase resolved spectral analysis reveals non-thermal X-ray emission of PSR B1957+20, confirming the results of previous studies. This suggests that the X-rays are mostly due to intra-binary shock emission which is strongest when the pulsar wind interacts with the ablated material from the companion ...

  8. High-energy observations of the millisecond pulsar PSR J0218+4232

    NARCIS (Netherlands)

    Verbunt, F; Kuiper, L; Belloni, T; Johnston, HM; deBruyn, AG; Hermsen, W; vanderKlis, M

    1996-01-01

    The very luminous millisecond binary radio pulsar PSR J0218+4232 has been detected in soft X-rays, at a luminosity of 8.4 x 10(32)erg s(-1) between 0.1 - 2.4 keV. The EGRET source 2EG J0220+4228 has a position which is consistent with that of PSR J0218+4232. Both the X-ray source and the gamma-ray s

  9. Similarity of PSR J1906+0746 TO PSR J0737–3039: A Candidate of a New Double Pulsar System?

    Science.gov (United States)

    Yang, Yi-Yan; Zhang, Cheng-Min; Li, Di; Wang, De-Hua; Pan, Yuan-Yue; Lingfu, Rong-Feng; Zhou, Zhu-Wen

    2017-02-01

    PSR J1906+0746 is a nonrecycled strong magnetic field neutron star (NS), sharing the properties of the secondary-formed NS PSR J0737–3039B in the double pulsar system PSR J0737–3039AB. By comparing the orbital parameters of PSR J1906+0746 with those of PSR J0737–3039AB, we conclude that both systems have a similar origin and evolution history, involving an e-capture process for forming the second-born NS, like in the case of PSR J0737–3039B. We expect the companion of PSR J1906+0746 to be a long-lived recycled pulsar with radio beams that currently cannot be observed from Earth. We suggest possible ways to detect its presence. To compare PSR J1906+0746 with PSR J0737–3039, we also present the mass distribution of eight pairs of double NSs and find that in double NSs the mass of the recycled pulsar is usually larger than that of the nonrecycled one, which may be the result of accretion.

  10. PSR J2021+3651: A New Gamma-Ray Pulsar Candidate

    CERN Document Server

    Roberts, M S E; Freire, P C C; Hessels, J W T; Kaspi, V M; Lorimer, D R; Ransom, S M; Crawford, Fronefield; Freire, Paulo C.C.; Hessels, Jason W.T.; Kaspi, Victoria M.; Lorimer, Duncan R.; Ransom, Scott M.; Roberts, Mallory S.E.

    2004-01-01

    The COS B high energy gamma-ray source 2CG 075+00, also known as GeV J2020+3658 or 3EG J2021+3716, has avoided identification with a low energy counterpart for over twenty years. We present a likely identification with the discovery and subsequent timing of a young and energetic pulsar, PSR J2021+3651, with the Wideband Arecibo Pulsar Processor at the Arecibo Observatory. PSR J2021+3651 has a rotation period P = 104ms and Pdot = 9.6 x 10^{-14}, implying a characteristic age T_c = 17kyr and a spin-down luminosity Edot = 3.4 x 10^{36} erg s^{-1}. The pulsar is also coincident with the ASCA source AX J2021.1+3651. The implied luminosity of the associated X-ray source suggests the X-ray emission is dominated by a pulsar wind nebula unresolved by ASCA. The pulsar's unexpectedly high dispersion measure DM = 371 pc cm^{-3} and the d > 10kpc DM distance pose a new question: is PSR J2021+3651 an extremely efficient gamma-ray pulsar at the edge of the Galaxy? This is a question for AGILE and GLAST to answer.

  11. A Chandra search for the pulsar wind nebula around PSR B1055-52

    CERN Document Server

    Posselt, B; Pavlov, G G

    2015-01-01

    The nearby, middle-aged PSR B1055-52 has many properties in common with the Geminga pulsar. Motivated by the Geminga's enigmatic and prominent pulsar wind nebula (PWN), we searched for extended emission around PSR B1055-52 with Chandra ACIS. For an energy range 0.3-1 keV, we found a 4 sigma flux enhancement in a 4.9-20 arcsec annulus around the pulsar. There is a slight asymmetry in the emission close, 1.5-4 arcsec, to the pulsar. The excess emission has a luminosity of about 10^{29} erg s^{-1} in an energy range 0.3-8 keV for a distance of 350 pc. Overall, the faint extended emission around PSR B1055-52 is consistent with a PWN of an aligned rotator moving away from us along the line of sight with supersonic velocity, but a contribution from a dust scattering halo cannot be excluded. Comparing the properties of other nearby, middle-aged pulsars, we suggest that the geometry -- the orientations of rotation axis, magnetic field axis, and the sight-line -- is the deciding factor for a pulsar to show a prominent...

  12. The Einstein@Home Search for Radio Pulsars and PSR J2007+2722 Discovery

    Science.gov (United States)

    Allen, B.; Knispel, B.; Cordes, J. M.; Deneva, J. S.; Hessels, J. W. T.; Anderson, D.; Aulbert, C.; Bock, O.; Brazier, A.; Chatterjee, S.; Demorest, P. B.; Eggenstein, H. B.; Fehrmann, H.; Gotthelf, E. V.; Hammer, D.; Kaspi, V. M.; Kramer, M.; Lyne, A. G.; Machenschalk, B.; McLaughlin, M. A.; Messenger, C.; Pletsch, H. J.; Ransom, S. M.; Stairs, I. H.; Stappers, B. W.; Bhat, N. D. R.; Bogdanov, S.; Camilo, F.; Champion, D. J.; Crawford, F.; Desvignes, G.; Freire, P. C. C.; Heald, G.; Jenet, F. A.; Lazarus, P.; Lee, K. J.; van Leeuwen, J.; Lynch, R.; Papa, M. A.; Prix, R.; Rosen, R.; Scholz, P.; Siemens, X.; Stovall, K.; Venkataraman, A.; Zhu, W.

    2013-08-01

    Einstein@Home aggregates the computer power of hundreds of thousands of volunteers from 193 countries, to search for new neutron stars using data from electromagnetic and gravitational-wave detectors. This paper presents a detailed description of the search for new radio pulsars using Pulsar ALFA survey data from the Arecibo Observatory. The enormous computing power allows this search to cover a new region of parameter space; it can detect pulsars in binary systems with orbital periods as short as 11 minutes. We also describe the first Einstein@Home discovery, the 40.8 Hz isolated pulsar PSR J2007+2722, and provide a full timing model. PSR J2007+2722's pulse profile is remarkably wide with emission over almost the entire spin period. This neutron star is most likely a disrupted recycled pulsar, about as old as its characteristic spin-down age of 404 Myr. However, there is a small chance that it was born recently, with a low magnetic field. If so, upper limits on the X-ray flux suggest but cannot prove that PSR J2007+2722 is at least ~100 kyr old. In the future, we expect that the massive computing power provided by volunteers should enable many additional radio pulsar discoveries.

  13. THE EINSTEIN-HOME SEARCH FOR RADIO PULSARS AND PSR J2007+2722 DISCOVERY

    Energy Technology Data Exchange (ETDEWEB)

    Allen, B.; Knispel, B.; Aulbert, C.; Bock, O.; Eggenstein, H. B.; Fehrmann, H.; Machenschalk, B. [Max-Planck-Institut fuer Gravitationsphysik, D-30167 Hannover (Germany); Cordes, J. M.; Brazier, A.; Chatterjee, S. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Deneva, J. S. [Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612 (United States); Hessels, J. W. T. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Anderson, D. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Demorest, P. B. [NRAO (National Radio Astronomy Observatory), Charlottesville, VA 22903 (United States); Gotthelf, E. V. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Hammer, D. [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Kaspi, V. M. [Department of Physics, McGill University, Montreal, QC H3A2T8 (Canada); Kramer, M. [Max-Planck-Institut fuer Radioastronomie, D-53121 Bonn (Germany); Lyne, A. G. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); McLaughlin, M. A., E-mail: bruce.allen@aei.mpg.de [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); and others

    2013-08-20

    Einstein-Home aggregates the computer power of hundreds of thousands of volunteers from 193 countries, to search for new neutron stars using data from electromagnetic and gravitational-wave detectors. This paper presents a detailed description of the search for new radio pulsars using Pulsar ALFA survey data from the Arecibo Observatory. The enormous computing power allows this search to cover a new region of parameter space; it can detect pulsars in binary systems with orbital periods as short as 11 minutes. We also describe the first Einstein-Home discovery, the 40.8 Hz isolated pulsar PSR J2007+2722, and provide a full timing model. PSR J2007+2722's pulse profile is remarkably wide with emission over almost the entire spin period. This neutron star is most likely a disrupted recycled pulsar, about as old as its characteristic spin-down age of 404 Myr. However, there is a small chance that it was born recently, with a low magnetic field. If so, upper limits on the X-ray flux suggest but cannot prove that PSR J2007+2722 is at least {approx}100 kyr old. In the future, we expect that the massive computing power provided by volunteers should enable many additional radio pulsar discoveries.

  14. Probing the Pulsar Wind Nebula of PSR B0355+54

    CERN Document Server

    McGowan, K E; Cropper, M; Kennea, J A; Vestrand, W T; Zane, S; Cordova, France A.; Cropper, Mark; Gowan, Katherine E. Mc; Kennea, Jamie A.; Zane, Silvia

    2006-01-01

    We present XMM-Newton and Chandra X-ray observations of the middle-aged radio pulsar PSR B0355+54. Our X-ray observations reveal emission not only from the pulsar itself, but also from a compact diffuse component extending ~50'' in the opposite direction to the pulsar's proper motion. There is also evidence for the presence of fainter diffuse emission extending ~5' from the point source. The compact diffuse feature is well-fitted with a power-law, the index of which is consistent with the values found for other pulsar wind nebulae. The morphology of the diffuse component is similar to the ram-pressure confined pulsar wind nebulae detected for other sources. The X-ray emission from the pulsar itself is described well by a thermal plus power-law fit, with the thermal emission most likely originating in a hot polar cap.

  15. A precise mass measurement of the intermediate-mass binary pulsar PSR J1802-2124

    CERN Document Server

    Ferdman, Robert D; Kramer, Michael; McLaughlin, Maura A; Lorimer, Duncan R; Nice, David J; Manchester, Richard N; Hobbs, George; Lyne, Andrew G; Camilo, Fernando; Possenti, Andrea; Demorest, Paul B; Cognard, Ismael; Desvignes, Gregory; Theureau, Gilles; Faulkner, Andrew; Backer, Donald C

    2010-01-01

    PSR J1802-2124 is a 12.6-ms pulsar in a 16.8-hour binary orbit with a relatively massive white dwarf (WD) companion. These properties make it a member of the intermediate-mass class of binary pulsar (IMBP) systems. We have been timing this pulsar since its discovery in 2002. Concentrated observations at the Green Bank Telescope, augmented with data from the Parkes and Nancay observatories, have allowed us to determine the general relativistic Shapiro delay. This has yielded pulsar and white dwarf mass measurements of 1.24(11) and 0.78(4) solar masses (68% confidence), respectively. The low mass of the pulsar, the high mass of the WD companion, the short orbital period, and the pulsar spin period may be explained by the system having gone through a common-envelope phase in its evolution. We argue that selection effects may contribute to the relatively small number of known IMBPs.

  16. Optical Observations of PSR J0205+6449 - the next optical pulsar?

    CERN Document Server

    Moran, P; Collins, S; de Luca, A; Rea, N; Shearer, A

    2013-01-01

    PSR J0205+6449 is a young ({\\approx} 5400 years), Crab-like pulsar detected in radio and at X and {\\gamma}-ray energies and has the third largest spin-down flux among known rotation powered pulsars. It also powers a bright synchrotron nebula detected in the optical and X-rays. At a distance of {\\approx} 3.2 kpc and with an extinction comparable to the Crab, PSR J0205+6449 is an obvious target for optical observations. We observed PSR J0205+6449 with several optical facilities, including 8m class ground-based telescopes, such as the Gemini and the Gran Telescopio Canarias. We detected a point source, at a significance of 5.5{\\sigma}, of magnitude i {\\approx} 25.5, at the centre of the optical synchrotron nebula, coincident with the very accurate Chandra and radio positions of the pulsar. Thus, we discovered a candidate optical counterpart to PSR J0205+6449. The pulsar candidate counterpart is also detected in the g ({\\approx}27.4) band and weakly in the r ({\\approx}26.2) band. Its optical spectrum is fit by a ...

  17. A Chandra Search for a Pulsar Wind Nebula around PSR B1055-52

    Science.gov (United States)

    Posselt, B.; Spence, G.; Pavlov, G. G.

    2015-10-01

    The nearby, middle-aged PSR B1055-52 has many properties in common with the Geminga pulsar. Motivated by the Geminga's enigmatic and prominent pulsar wind nebula (PWN), we searched for extended emission around PSR B1055-52 with Chandra ACIS. For an energy range 0.3-1 keV, we found a 4σ flux enhancement in a 4\\buildrel{\\prime\\prime}\\over{.} 9-20\\prime\\prime annulus around the pulsar. There is a slight asymmetry in the emission close, 1\\buildrel{\\prime\\prime}\\over{.} 5-4\\prime\\prime , to the pulsar. The excess emission has a luminosity of about 1029 erg s-1 in an energy range 0.3-8 keV for a distance of 350 pc. Overall, the faint extended emission around \\text{PSR B1055-52} is consistent with a PWN of an aligned rotator moving away from us along the line of sight with supersonic velocity, but a contribution from a dust scattering halo cannot be excluded. Comparing the properties of other nearby, middle-aged pulsars, we suggest that the geometry—the orientations of rotation axis, magnetic field axis, and the sight-line—is the deciding factor for a pulsar to show a prominent PWN. We also report on an ≳ 30% flux decrease of PSR B1055-52 between the 2000 XMM-Newton and our 2012 Chandra observation. We tentatively attribute this flux decrease to a cross-calibration problem, but further investigations of the pulsar are required to exclude actual intrinsic flux changes.

  18. PSR J1906+0722: An Elusive Gamma-ray Pulsar

    CERN Document Server

    Clark, C J; Wu, J; Guillemot, L; Ackermann, M; Allen, B; de Angelis, A; Aulbert, C; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bellazzini, R; Bissaldi, E; Bock, O; Bonino, R; Bottacini, E; Brandt, T J; Bregeon, J; Bruel, P; Buson, S; Caliandro, G A; Cameron, R A; Caragiulo, M; Caraveo, P A; Cecchi, C; Champion, D J; Charles, E; Chekhtman, A; Chiang, J; Chiaro, G; Ciprini, S; Claus, R; Cohen-Tanugi, J; Cuéllar, A; Cutini, S; D'Ammando, F; Desiante, R; Drell, P S; Eggenstein, H B; Favuzzi, C; Fehrmann, H; Ferrara, E C; Focke, W B; Franckowiak, A; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guiriec, S; Harding, A K; Hays, E; Hewitt, J W; Hill, A B; Horan, D; Hou, X; Jogler, T; Johnson, A S; Jóhannesson, G; Kramer, M; Krauss, F; Kuss, M; Laffon, H; Larsson, S; Latronico, L; Li, J; Li, L; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Machenschalk, B; Manfreda, A; Marelli, M; Mayer, M; Mazziotta, M N; Michelson, P F; Mizuno, T; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nuss, E; Ohsugi, T; Orienti, M; Orlando, E; de Palma, F; Paneque, D; Pesce-Rollins, M; Piron, F; Pivato, G; Rainò, S; Rando, R; Razzano, M; Reimer, A; Parkinson, P M Saz; Schaal, M; Schulz, A; Sgrò, C; Siskind, E J; Spada, F; Spandre, G; Spinelli, P; Suson, D J; Takahashi, H; Thayer, J B; Tibaldo, L; Torne, P; Torres, D F; Tosti, G; Troja, E; Vianello, G; Wood, K S; Wood, M; Yassine, M

    2015-01-01

    We report the discovery of PSR J1906+0722, a gamma-ray pulsar detected as part of a blind survey of unidentified Fermi Large Area Telescope (LAT) sources being carried out on the volunteer distributed computing system, Einstein@Home. This newly discovered pulsar previously appeared as the most significant remaining unidentified gamma-ray source without a known association in the second Fermi-LAT source catalog (2FGL) and was among the top ten most significant unassociated sources in the recent third catalog (3FGL). PSR J1906+0722 is a young, energetic, isolated pulsar, with a spin frequency of $8.9$ Hz, a characteristic age of $49$ kyr, and spin-down power $1.0 \\times 10^{36}$ erg s$^{-1}$. In 2009 August it suffered one of the largest glitches detected from a gamma-ray pulsar ($\\Delta f / f \\approx 4.5\\times10^{-6}$). Remaining undetected in dedicated radio follow-up observations, the pulsar is likely radio-quiet. An off-pulse analysis of the gamma-ray flux from the location of PSR J1906+0722 revealed the pr...

  19. Fermi LAT Pulsed Detection of PSR J0737-3039A in the Double Pulsar System

    Science.gov (United States)

    Guillemot, L.; Kramer, M.; Johnson, T. J.; Craig, H. A.; Romani, R. W.; Venter, C.; Harding, A. K.; Ferdman, R. D.; Stairs, I. H.; Kerr, M.

    2013-01-01

    We report the Fermi Large Area Telescope discovery of gamma-ray pulsations from the 22.7 ms pulsar A in the double pulsar system J0737-3039A/B. This is the first mildly recycled millisecond pulsar (MSP) detected in the GeV domain. The 2.7 s companion object PSR J0737-3039B is not detected in gamma rays. PSR J0737-3039A is a faint gamma-ray emitter, so that its spectral properties are only weakly constrained; however, its measured efficiency is typical of other MSPs. The two peaks of the gamma-ray light curve are separated by roughly half a rotation and are well offset from the radio and X-ray emission, suggesting that the GeV radiation originates in a distinct part of the magnetosphere from the other types of emission. From the modeling of the radio and the gamma-ray emission profiles and the analysis of radio polarization data, we constrain the magnetic inclination alpha and the viewing angle zeta to be close to 90 deg., which is consistent with independent studies of the radio emission from PSR J0737-3039A. A small misalignment angle between the pulsar's spin axis and the system's orbital axis is therefore favored, supporting the hypothesis that pulsar B was formed in a nearly symmetric supernova explosion as has been discussed in the literature already.

  20. X-ray studies of the Black Widow Pulsar PSR B1957+20

    CERN Document Server

    Huang, R H H; Takata, J; Hui, C Y; Lin, L C C; Cheng, K S

    2012-01-01

    We report on Chandra observations of the black widow pulsar, PSR B1957+20. Evidence for a binary-phase dependence of the X-ray emission from the pulsar is found with a deep observation. The binary-phase resolved spectral analysis reveals non-thermal X-ray emission of PSR B1957+20, confirming the results of previous studies. This suggests that the X-rays are mostly due to intra-binary shock emission which is strongest when the pulsar wind interacts with the ablated material from the companion star. The geometry of the peak emission is determined in our study. The marginal softening of the spectrum of the non-thermal X-ray tail may indicate that particles injected at the termination shock is dominated by synchrotron cooling.

  1. X-ray studies of the black widow pulsar PSR B1957+20

    Science.gov (United States)

    Huang, R. H. H.; Kong, A. K. H.; Takata, J.; Hui, C. Y.; Lin, L. C. C.; Cheng, K. S.

    2013-03-01

    We report on Chandra observations of the black widow pulsar, PSR B1957+20. Evidence for a binary-phase dependence of the X-ray emission from the pulsar is found with a deep observation. The binary-phase resolved spectral analysis reveals non-thermal X-ray emission of PSR B1957+20, confirming the results of previous studies. This suggests that the X-rays are mostly due to intra-binary shock emission which is strongest when the pulsar wind interacts with the ablated material from the companion star. The geometry of the peak emission is determined in our study. The marginal softening of the spectrum of the non-thermal X-ray tail may indicate that particles injected at the termination shock is dominated by synchrotron cooling.

  2. IDENTIFICATION OF THE OPTICAL COUNTERPART OF FERMI BLACK WIDOW MILLISECOND PULSAR PSR J1544+4937

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Sumin; Phinney, E. Sterl; Prince, Thomas A.; Bellm, Eric; Cao, Yi; Perley, Daniel A. [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Kaplan, David L. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Breton, Rene P. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Bildsten, Lars [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States); Kong, Albert K. H.; Yen, T.-C. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Sesar, Branimir [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Wolf, William M. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

    2014-08-10

    We report the optical identification of the companion to the Fermi black widow millisecond pulsar PSR J1544+4937. We find a highly variable source on Keck Low Resolution Imaging Spectrometer images at the nominal pulsar position, with 2 mag variations over orbital period in the B, g, R, and I bands. The nearly achromatic light curves are difficult to explain with a simply irradiated hemisphere model, and suggest that the optical emission is dominated by a nearly isothermal hot patch on the surface of the companion facing the pulsar. We roughly constrain the distance to PSR J1544+4937 to be between 2 and 5 kpc. A more reliable distance measurement is needed in order to constrain the composition of the companion.

  3. Identification of the Optical Counterpart of Fermi Black Widow Millisecond Pulsar PSR J1544+4937

    CERN Document Server

    Tang, Sumin; Phinney, Sterl; Prince, Thomas A; Breton, Rene; Bellm, Eric; Bildsten, Lars; Cao, Yi; Kong, A K H; Perley, Daniel A; Sesar, Branimir; Wolf, William M; Yen, T -C

    2014-01-01

    We report the optical identification of the companion to the {\\it Fermi} black widow millisecond pulsar PSR J1544+4937. We find a highly variable source on Keck LRIS images at the nominal pulsar position, with 2 magnitude variations over orbital period in the B, g, R, and I bands. The nearly achromatic light curves are difficult to explain with a simply irradiated hemisphere model, and suggest that the optical emission is dominated by a nearly isothermal hot patch on the surface of the companion facing the pulsar. We roughly constrain the distance to PSR J1544+4937 to be between 2 and 5 kpc. A more reliable distance measurement is needed in order to constrain the composition of the companion.

  4. SAS-2 gamma-ray observations of PSR 1747-46. [radio pulsar

    Science.gov (United States)

    Thompson, D. J.; Fichtel, C. E.; Kniffen, D. A.; Ogelman, H. B.; Lamb, R. C.

    1976-01-01

    Evidence is reported for the observation of gamma-ray emission from the radio pulsar PSR 1747-46 by the gamma-ray telescope aboard SAS 2. The evidence is based on the presence of both an approximately 3-sigma enhancement of gamma rays at the pulsar's location and an approximately 4-sigma peak in the phase plot of 79 gamma-ray events whose phase was calculated from the pulsar's known period. The gamma-ray pulsation is found to appear at a phase lag of about 0.16 from that predicted by the radio observations. The pulsed gamma-ray fluxes above 35 MeV and 100 MeV are estimated, and it is shown that the gamma-ray pulse width is similar to the radio pulse width. It is concluded that PSR 1747-46 is a most likely candidate for pulsed gamma-ray emission.

  5. Suzaku Observations of PSR B1259-63: A New Manifestation of Relativistic Pulsar Wind

    Energy Technology Data Exchange (ETDEWEB)

    Uchiyama, Yasunobu; Tanaka, Takaaki; Takahashi, Tadayuki; Mori, Koji; Nakazawa, Kazuhiro

    2009-04-27

    We observed PSR B1259-63, a young non-accreting pulsar orbiting around a Be star SS 2883, eight times with the Suzaku satellite from July to September 2007, to characterize the X-ray emission arising from the interaction between a pulsar relativistic wind and Be star outflows. The X-ray spectra showed a featureless continuum in 0.6-10 keV, modeled by a power law with a wide range of photon index 1.3-1.8. When combined with the Suzaku PIN detector which allowed spectral analysis in the hard 15-50 keV band, X-ray spectra do show a break at {approx} 5 keV in a certain epoch. Regarding the PSR B1259-63 system as a compactified pulsar wind nebula, in which e{sup {+-}} pairs are assumed to be accelerated at the inner shock front of the pulsar wind, we attribute the X-ray spectral break to the low-energy cutoff of the synchrotron radiation associated with the Lorentz factor of the relativistic pulsar wind {gamma}{sub 1} {approx} 4 x 10{sup 5}. Our result indicates that Comptonization of stellar photons by the unshocked pulsar wind will be accessible (or tightly constrained) by observations with the Fermi Gamma-ray Space Telescope during the next periastron passage. The PSR B1259-63 system allows us to probe the fundamental properties of the pulsar wind by a direct means, being complementary to the study of large-scale pulsar wind nebulae.

  6. PSR J1906+0722: An Elusive Gamma-Ray Pulsar

    Science.gov (United States)

    Clark, C. J.; Pletsch, H. J.; Wu, J.; Guillemot, L.; Ackermann, M.; Allen, B.; de Angelis, A.; Aulbert, C.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bock, O.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cecchi, C.; Champion, D. J.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cuéllar, A.; Cutini, S.; D'Ammando, F.; Desiante, R.; Drell, P. S.; Eggenstein, H. B.; Favuzzi, C.; Fehrmann, H.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Harding, A. K.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Hou, X.; Jogler, T.; Johnson, A. S.; Jóhannesson, G.; Kramer, M.; Krauss, F.; Kuss, M.; Laffon, H.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Machenschalk, B.; Manfreda, A.; Marelli, M.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nuss, E.; Ohsugi, T.; Orienti, M.; Orlando, E.; de Palma, F.; Paneque, D.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Saz Parkinson, P. M.; Schaal, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Suson, D. J.; Takahashi, H.; Thayer, J. B.; Tibaldo, L.; Torne, P.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Wood, K. S.; Wood, M.; Yassine, M.

    2015-08-01

    We report the discovery of PSR J1906+0722, a gamma-ray pulsar detected as part of a blind survey of unidentified Fermi Large Area Telescope (LAT) sources being carried out on the volunteer distributed computing system, Einstein@Home. This newly discovered pulsar previously appeared as the most significant remaining unidentified gamma-ray source without a known association in the second Fermi-LAT source catalog (2FGL) and was among the top 10 most significant unassociated sources in the recent third catalog (3FGL). PSR J1906+0722 is a young, energetic, isolated pulsar, with a spin frequency of 8.9 Hz, a characteristic age of 49 kyr, and spin-down power 1.0× {10}36 erg s-1. In 2009 August it suffered one of the largest glitches detected from a gamma-ray pulsar ({{Δ }}f/f≈ 4.5× {10}-6). Remaining undetected in dedicated radio follow-up observations, the pulsar is likely radio-quiet. An off-pulse analysis of the gamma-ray flux from the location of PSR J1906+0722 revealed the presence of an additional nearby source, which may be emission from the interaction between a neighboring supernova remnant and a molecular cloud. We discuss possible effects which may have hindered the detection of PSR J1906+0722 in previous searches and describe the methods by which these effects were mitigated in this survey. We also demonstrate the use of advanced timing methods for estimating the positional, spin and glitch parameters of difficult-to-time pulsars such as this.

  7. PSR J1723–2837: AN ECLIPSING BINARY RADIO MILLISECOND PULSAR

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Fronefield [Department of Physics and Astronomy, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604 (United States); Lyne, Andrew G. [Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL (United Kingdom); Stairs, Ingrid H. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Kaplan, David L. [Physics Department, University of Wisconsin - Milwaukee, Milwaukee, WI 53211 (United States); McLaughlin, Maura A.; Lorimer, Duncan R. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Freire, Paulo C. C.; Kramer, Michael [Max-Planck-Institut für Radioastronomie, auf dem Huegel 69, D-53121 Bonn (Germany); Burgay, Marta; D' Amico, Nichi; Possenti, Andrea [INAF - Osservatorio Astronomico di Cagliari, Poggio dei Pini, I-09012 Capoterra (Italy); Camilo, Fernando [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Faulkner, Andrew [Cavendish Laboratory, University of Cambridge, J. J. Thompson Avenue, Cambridge, CB3 0HE (United Kingdom); Manchester, Richard N. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia); Steeghs, Danny, E-mail: fcrawfor@fandm.edu [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2013-10-10

    We present a study of PSR J1723–2837, an eclipsing, 1.86 ms millisecond binary radio pulsar discovered in the Parkes Multibeam survey. Radio timing indicates that the pulsar has a circular orbit with a 15 hr orbital period, a low-mass companion, and a measurable orbital period derivative. The eclipse fraction of ∼15% during the pulsar's orbit is twice the Roche lobe size inferred for the companion. The timing behavior is significantly affected by unmodeled systematics of astrophysical origin, and higher-order orbital period derivatives are needed in the timing solution to account for these variations. We have identified the pulsar's (non-degenerate) companion using archival ultraviolet, optical, and infrared survey data and new optical photometry. Doppler shifts from optical spectroscopy confirm the star's association with the pulsar and indicate a pulsar-to-companion mass ratio of 3.3 ± 0.5, corresponding to a companion mass range of 0.4 to 0.7 M{sub ☉} and an orbital inclination angle range of between 30° and 41°, assuming a pulsar mass range of 1.4-2.0 M{sub ☉}. Spectroscopy indicates a spectral type of G for the companion and an inferred Roche-lobe-filling distance that is consistent with the distance estimated from radio dispersion. The features of PSR J1723–2837 indicate that it is likely a 'redback' system. Unlike the five other Galactic redbacks discovered to date, PSR J1723–2837 has not been detected as a γ-ray source with Fermi. This may be due to an intrinsic spin-down luminosity that is much smaller than the measured value if the unmeasured contribution from proper motion is large.

  8. PSR J1723-2837: An Eclipsing Binary Radio Millisecond Pulsar

    Science.gov (United States)

    Crawford, Fronefield; Lyne, Andrew G.; Stairs, Ingrid H.; Kaplan, David L.; McLaughlin, Maura A.; Freire, Paulo C. C.; Burgay, Marta; Camilo, Fernando; D'Amico, Nichi; Faulkner, Andrew; Kramer, Michael; Lorimer, Duncan R.; Manchester, Richard N.; Possenti, Andrea; Steeghs, Danny

    2013-10-01

    We present a study of PSR J1723-2837, an eclipsing, 1.86 ms millisecond binary radio pulsar discovered in the Parkes Multibeam survey. Radio timing indicates that the pulsar has a circular orbit with a 15 hr orbital period, a low-mass companion, and a measurable orbital period derivative. The eclipse fraction of ~15% during the pulsar's orbit is twice the Roche lobe size inferred for the companion. The timing behavior is significantly affected by unmodeled systematics of astrophysical origin, and higher-order orbital period derivatives are needed in the timing solution to account for these variations. We have identified the pulsar's (non-degenerate) companion using archival ultraviolet, optical, and infrared survey data and new optical photometry. Doppler shifts from optical spectroscopy confirm the star's association with the pulsar and indicate a pulsar-to-companion mass ratio of 3.3 ± 0.5, corresponding to a companion mass range of 0.4 to 0.7 M ⊙ and an orbital inclination angle range of between 30° and 41°, assuming a pulsar mass range of 1.4-2.0 M ⊙. Spectroscopy indicates a spectral type of G for the companion and an inferred Roche-lobe-filling distance that is consistent with the distance estimated from radio dispersion. The features of PSR J1723-2837 indicate that it is likely a "redback" system. Unlike the five other Galactic redbacks discovered to date, PSR J1723-2837 has not been detected as a γ-ray source with Fermi. This may be due to an intrinsic spin-down luminosity that is much smaller than the measured value if the unmeasured contribution from proper motion is large.

  9. Photon Splitting Cascades in $\\gamma$-Ray Pulsars and the Spectrum of PSR1509-58

    CERN Document Server

    Harding, A K; Gonthier, P L; Harding, Alice K.; Baring, Matthew G.; Gonthier, Peter L.

    1996-01-01

    Magnetic photon splitting, a QED process that becomes important only in magnetic fields approaching the quantum critical value, B_cr = 4.41 X 10^13 Gauss, is investigated as a mechanism for attenuation of gamma-rays emitted near the surface of strongly-magnetized pulsars. We model photon splitting attenuation and subsequent splitting cascades in gamma-ray pulsars, including the dipole field and curved spacetime geometry of the neutron star magnetosphere. We focus specifically on PSR1509-58, which has the highest surface magnetic field of all the gamma-ray pulsars (B_0 = 3 X 10^13 Gauss). We find that splitting will not be important for most gamma-ray pulsars, i.e. those with B_0 ~ 0.3 B_cr, where the splitting attenuation lengths and escape energies become comparable to or less than those for pair production. We compute Monte Carlo spectral models for PSR1509-58. We find that photon splitting, or combined splitting and pair production, can explain the unusually low cutoff energy (between 2 and 30 MeV) of PSR1...

  10. Towards a theory of extremely intermittent pulsars I: Does something orbits PSR B1931 + 24 ?

    CERN Document Server

    Mottez, Fabrice; Bonazzola, Silvano

    2013-01-01

    We investigate whether one or many companions are orbiting the extremely intermittent pulsar PSR B1931+24. We constrained our analysis on previous observations of eight fundamental properties of PSR B1931+24. The most puzzling properties are the intermittent nature of the pulsar's activity, with active and quiet phases that alternate quasi-periodically; the variation of the slowing-down rate of its period between active and quiet phases; and because there are no timing residuals, it is highly unlikely that the pulsar has a massive companion. Here, we examine the effects that one putative companion immersed in the magnetospheric plasma or the wind of the pulsar might have, as well as the associated electric current distribution. We analysed several possibilities for the distance and orbit of this hypothetical companion and the nature of its interaction with the neutron star. We show that if the quasi-periodic behaviour of PSR B1931+24 was caused by a companion orbiting the star with a period of 35 or 70 days, ...

  11. The Einstein@Home search for radio pulsars and PSR J2007+2722

    CERN Document Server

    Allen, B; Cordes, J M; Deneva, J S; Hessels, J W T; Anderson, D; Aulbert, C; Bock, O; Brazier, A; Chatterjee, S; Demorest, P B; Eggenstein, H B; Fehrmann, H; Gotthelf, E V; Hammer, D; Kaspi, V M; Kramer, M; Lyne, A G; Machenschalk, B; McLaughlin, M A; Messenger, C; Pletsch, H J; Ransom, S M; Stairs, I H; Stappers, B W; Bhat, N D R; Bogdanov, S; Camilo, F; Champion, D J; Crawford, F; Desvignes, G; Freire, P C C; Heald, G; Jenet, F A; Lazarus, P; Lee, K J; van Leeuwen, J; Lynch, R; Papa, M A; Prix, R; Rosen, R; Scholz, P; Siemens, X; Stovall, K; Venkataraman, A; Zhu, W

    2013-01-01

    Einstein@Home aggregates the computer power of hundreds of thousands of volunteers from 192 countries, to search for new neutron stars using data from electromagnetic and gravitational-wave detectors. This paper presents a detailed description of the search for new radio pulsars using PALFA survey data from the Arecibo Observatory. The enormous computing power allows this search to cover a new region of parameter space; it can detect pulsars in binary systems with orbital periods as short as 11 min. We also describe the first Einstein@Home discovery, the 40.8 Hz isolated pulsar PSR J2007+2722, and provide a full timing model. PSR J2007+2722's pulse profile is remarkably wide with emission over almost the entire spin period. This neutron star is most likely a disrupted recycled pulsar, about as old as its characteristic spin-down age of 404 Myr. However there is a small chance that it was born recently, with a low magnetic field. If so, upper limits on the X-ray flux suggest but can not prove that PSR J2007+27...

  12. Interstellar Medium Effects on Radio Pulsars PSR B1937+21 and PSR B2224+65, and Implications for Gravitational Wave Detection

    Science.gov (United States)

    Dolch, Timothy; Chatterjee, Shami; Cordes, James M.; Paul, Demorest; Halmrast, Daniel; Jessup, Cody; Jones, Glenn; Lam, Michael T.; Lyne, Andrew; McLaughlin, Maura; Ramette, Joshua; Stinebring, Dan; Stappers, Benjamin; Stovall, Kevin

    2017-01-01

    Noise in pulsar timing residuals due to the ionized interstellar medium (IISM) is a critical limiting factor for pulsar timing arrays (PTAs) as gravitational wave detectors. PSR B1937+21 is the brightest millisecond pulsar in the northern sky and serves as a laboratory for studying uncertainties and systematic changes in pulse times-of-arrival. Its high flux, its high degree of scattering along the line-of-sight, and its giant pulses interact in a dynamic way to affect individual times-of-arrival on different timescales. Noise budget results on this pulsar are relevant to understanding the timing of other millisecond pulsars. We present data from an Arecibo Observatory campaign on PSR B1937+21 at 1.4GHz, the standard radio frequency at which the times-of-arrival of PSR B1937+21 and other PTA pulsars are routinely measured for the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). The campaign was strategized to probe the pulsar’s noise budget, particularly with respect to the IISM from high S/N dynamic spectra that show flux distributed irregularly across the bandwidth from interstellar scintillation. Similarly, PSR B2224+65, while not a NANOGrav pulsar, is associated with the Guitar Nebula, a region with significant ISM density fluctuations. We also present data from a Green Bank Telescope monitoring campaign on PSR B2224+65 at 342MHz and 1.4GHz, which uses dispersion measure (DM) variations to constrain the influence of the IISM on the pulsar’s times-of-arrival. By utilizing the dynamic spectra, single pulse, and DM data from these campaigns, we analyze the noise budgets of these pulsars on very short and very long timescales due to the changing intervening IISM.

  13. The Radio and X-ray Mode-Switching Pulsar PSR B0943+10

    Science.gov (United States)

    Mereghetti, Sandro; Rigoselli, Michela

    2017-09-01

    Observations obtained in the last years challenged the widespread notion that rotation-powered neutron stars are steady X-ray emitters. Besides a few allegedly rotation-powered neutron stars that showed `magnetar-like' variability, a particularly interesting case is that of PSR B0943+10. Recent observations have shown that this pulsar, well studied in the radio band where it alternates between a bright and a quiescent mode, displays significant X-ray variations, anticorrelated in flux with the radio emission. The study of such synchronous radio/X-ray mode switching opens a new window to investigate the processes responsible for the pulsar radio and high-energy emission. Here we review the main X-ray properties of PSR B0943+10 derived from recent coordinated X-ray and radio observations.

  14. PSR J1024-0719: A Millisecond Pulsar in an Unusual Long-Period Orbit

    CERN Document Server

    Kaplan, D L; Nice, D J; Irrgang, A; Heber, U; Arzoumanian, Z; Beklen, E; Crowter, K; DeCesar, M E; Demorest, P B; Dolch, T; Lynch, R S; McLaughlin, M A; Miller, A A; Ng, C; Pennucci, T T; Ellis, J A; Ferdman, R D; Ferrara, E C; Fonseca, E; Gentile, P A; Jones, G; Jones, M L; Kreuzer, S; Lam, M T; Levin, L; Lorimer, D R; Prince, T A; Ransom, S M; Ray, P S; Spiewak, R; Stairs, I H; Stovall, K; Swiggum, J; Zhu, W

    2016-01-01

    PSR J1024$-$0719 is a millisecond pulsar that was long thought to be isolated. However, puzzling results concerning its velocity, distance, and low rotational period derivative have led to reexamination of its properties. We present updated radio timing observations along with new and archival optical data that show PSR J1024$-$0719 is most likely in a long period (2$-$20 kyr) binary system with a low-mass ($\\approx 0.4\\,M_\\odot$) low-metallicity ($Z \\approx -0.9\\,$ dex) main sequence star. Such a system can explain most of the anomalous properties of this pulsar. We suggest that this system formed through a dynamical exchange in a globular cluster that ejected it into a halo orbit, consistent with the low observed metallicity for the stellar companion. Further astrometric and radio timing observations such as measurement of the third period derivative could strongly constrain the range of orbital parameters.

  15. Magnetar Behavior of a Rotation Powered Pulsar, PSR J1119-6127

    CERN Document Server

    Gogus, Ersin; Kaneko, Yuki; Kouveliotou, Chryssa; Watts, Anna L; Alpar, M Ali; Huppenkothen, Daniela; Roberts, Oliver J; Younes, George; van der Horst, Alexander J

    2016-01-01

    Two energetic hard X-ray bursts have recently triggered the Fermi and Swift space observatories from the rotation powered pulsar, PSR J1119-6127. We have performed in depth spectral and temporal analyses of these two events. Our extensive searches in both observatory data for lower luminosity, untriggered, bursts using two independent methods (a signal-to-noise ratio search and a Bayesian blocks based technique), uncovered 10 additional events from the source. We report here on the timing and energetics of the 12 bursts from PSR J1119-6127 during its burst active phase of 2016 July 26 and 28. We also found a softer, extended thermal burst tail emission, which shows evidence of cooling. We discuss here the implications of these results on the nature of this unusual high-field radio pulsar, which firmly place it within the typical magnetar population.

  16. The Radio and X-ray Mode-Switching Pulsar PSR B0943+10

    Indian Academy of Sciences (India)

    Sandro Mereghetti; Michela Rigoselli

    2017-09-01

    Observations obtained in the last years challenged the widespread notion that rotation-powered neutron stars are steady X-ray emitters. Besides a few allegedly rotation-powered neutron stars that showed ‘magnetar-like’ variability, a particularly interesting case is that of PSR B0943+10. Recent observations have shown that this pulsar, well studied in the radio band where it alternates between a bright and a quiescent mode, displays significant X-ray variations, anticorrelated in flux with the radio emission. The study of such synchronous radio/X-ray mode switching opens a new window to investigate the processes responsible for the pulsar radio and high-energy emission. Here we review the main X-ray properties of PSR B0943+10 derived from recent coordinated X-ray and radio observations.

  17. On the evolution of the radio pulsar PSR J1734-3333

    Science.gov (United States)

    Çalişkan, Ş.; Ertan, Ü.; Alpar, M. A.; Trümper, J. E.; Kylafis, N. D.

    2013-05-01

    Recent measurements showed that the period derivative of the `high-B' radio pulsar PSR J1734-3333 is increasing with time. For neutron stars evolving with fallback discs, this rotational behaviour is expected in certain phases of the long-term evolution. Using the same model as employed earlier to explain the evolution of anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters, we show that the period, the first and second period derivatives and the X-ray luminosity of this source can simultaneously acquire the observed values for a neutron star evolving with a fallback disc. We find that the required strength of the dipole field that can produce the source properties is in the range 1012-1013 G on the pole of the neutron star. When the model source reaches the current state properties of PSR J1734-3333, accretion on to the star has not started yet, allowing the source to operate as a regular radio pulsar. Our results imply that PSR J1734-3333 is at an age of ˜3 × 104-2 × 105 yr. Such sources will have properties like the X-ray dim isolated neutron stars or transient AXPs at a later epoch of weak accretion from the diminished fallback disc.

  18. VARIABILITY OF THE PULSED RADIO EMISSION FROM THE LARGE MAGELLANIC CLOUD PULSAR PSR J0529-6652

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, F.; Altemose, D.; Li, H. [Department of Physics and Astronomy, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604 (United States); Lorimer, D. R. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States)

    2013-01-10

    We have studied the variability of PSR J0529-6652, a radio pulsar in the Large Magellanic Cloud (LMC), using observations conducted at 1390 MHz with the Parkes 64 m telescope. PSR J0529-6652 is detectable as a single pulse emitter, with amplitudes that classify the pulses as giant pulses. This makes PSR J0529-6652 the second known giant pulse emitter in the LMC, after PSR B0540-69. The fraction of the emitted pulses detectable from PSR J0529-6652 at this frequency is roughly two orders of magnitude greater than it is for either PSR B0540-69 or the Crab pulsar (if the latter were located in the LMC). We have measured a pulse nulling fraction of 83.3% {+-} 1.5% and an intrinsic modulation index of 4.07 {+-} 0.29 for PSR J0529-6652. The modulation index is significantly larger than values previously measured for typical radio pulsars but is comparable to values reported for members of several other neutron star classes. The large modulation index, giant pulses, and large nulling fraction suggest that this pulsar is phenomenologically more similar to these other, more variable sources, despite having spin and physical characteristics that are typical of the unrecycled radio pulsar population. The large modulation index also does not appear to be consistent with the small value predicted for this pulsar by a model of polar cap emission outlined by Gil and Sendyk. This conclusion depends to some extent on the assumption that PSR J0529-6652 is exhibiting core emission, as suggested by its simple profile morphology, narrow profile width, and previously measured profile polarization characteristics.

  19. GAMMA-RAY SIGNAL FROM THE PULSAR WIND IN THE BINARY PULSAR SYSTEM PSR B1259-63/LS 2883

    Energy Technology Data Exchange (ETDEWEB)

    Khangulyan, Dmitry [Institute of Space and Astronautical Science/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Aharonian, Felix A. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Bogovalov, Sergey V. [National Research Nuclear University-MEPHI, Kashirskoe Shosse 31, Moscow 115409 (Russian Federation); Ribo, Marc, E-mail: khangul@astro.isas.jaxa.jp, E-mail: felix.aharonian@dias.ie, E-mail: svbogovalov@mephi.ru, E-mail: mribo@am.ub.es [Departament d' Astronomia i Meteorologia, Institut de Ciences del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E-08028 Barcelona (Spain)

    2011-12-01

    Binary pulsar systems emit potentially detectable components of gamma-ray emission due to Comptonization of the optical radiation of the companion star by relativistic electrons of the pulsar wind, both before and after termination of the wind. The recent optical observations of binary pulsar system PSR B1259-63/LS 2883 revealed radiation properties of the companion star which differ significantly from previous measurements. In this paper, we study the implications of these observations for the interaction rate of the unshocked pulsar wind with the stellar photons and the related consequences for fluxes of high energy and very high energy (VHE) gamma rays. We show that the signal should be strong enough to be detected with Fermi close to the periastron passage, unless the pulsar wind is strongly anisotropic or the Lorentz factor of the wind is smaller than 10{sup 3} or larger than 10{sup 5}. The higher luminosity of the optical star also has two important implications: (1) attenuation of gamma rays due to photon-photon pair production and (2) Compton drag of the unshocked wind. While the first effect has an impact on the light curve of VHE gamma rays, the second effect may significantly decrease the energy available for particle acceleration after termination of the wind.

  20. A multiwavlength study of PSR B0628-28: The first overluminous rotation-powered pulsar?

    CERN Document Server

    Becker, W; Jessner, A; Krämer, M; Testa, V; Becker, Werner; Howaldt, Clemens; Jessner, Axel; Kramer, Michael; Testa, Vincenzo

    2005-01-01

    The ROSAT source RX J0630.8-2834 was suggested by positional coincidence to be the X-ray counterpart of the old field pulsar PSR B0628-28. This association, however, was regarded to be unlikely based on the computed energetics of the putative X-ray counterpart. In this paper we report on multiwavelength observations of PSR B0628-28 made with the ESO/NTT observatory in La Silla, the Jodrell Bank radio observatory and XMM-Newton. Although the optical observations do not detect any counterpart of RX J0630.8-2834 down to a limiting magnitude of V=26.1 mag and B=26.3 mag, XMM-Newton observations finally confirmed it to be the pulsar's X-ray counterpart by detecting X-ray pulses with the radio pulsar's spin-period. The X-ray pulse profile is characterized by a single broad peak with a second smaller peak leading the main pulse component by ~144 degree. The fraction of pulsed photons is (38 +- 7)% with no strong energy dependence in the XMM-Newton bandpass. The pulsar's X-ray spectrum is well described by a single c...

  1. Possible optical detection of a fast, nearby radio pulsar PSR B1133+16

    CERN Document Server

    Zharikov, S V; Mennickent, R E; Komarova, V N

    2007-01-01

    Aims: We performed deep optical observations of the field of an old, fast-moving radio pulsar PSR B1133+16 in an attempt to detect its optical counterpart and a bow shock nebula. Methods: The observations were carried out using the direct imaging mode of FORS1 at the ESO VLT/UT1 telescope in the B, R, and H_alpha bands. We also used archival images of the same field obtained with the VLT in the B band and with the Chandra/ACIS in X-rays. Results: In the B band we detected a faint (B=28.1+/-0.3) source that may be the optical counterpart of PSR B1133+16, as it is positionally consistent with the radio pulsar and with the X-ray counterpart candidate published earlier. Its upper limit in the R band implies a color index B-R <0.5, which is compatible with the index values for most pulsars identified in the optical range. The derived optical luminosity and its ratio to the X-ray luminosity of the candidate are consistent with expected values derived from a sample of pulsars detected in both spectral domains. No...

  2. Post-outburst radio monitoring of the high magnetic field pulsar PSR J1119-6127

    Science.gov (United States)

    Majid, Walid A.; Pearlman, Aaron B.; Kocz, Jonathan; Prince, Thomas A.; Lippuner, Jonas; Horiuchi, Shinji

    2017-01-01

    We have carried out radio monitoring observations of PSR J11119-6127 following its recent X-ray outburst in July 2016. While initial observations failed to detect the presence of pulsed emission, subsequent observations two weeks later show bright detections of the pulsar at S-band and a significant detection at X-band as the S-band pulse profile returns to a single-peaked shape. From these measurements, we were able to estimate a spectral index over a relatively wide range of radio wavelengths. We also detected an unusual multiple-peaked radio profile and single pulse events. Further observations show an evolving pulse profile that is quite unique among known radio pulsars. PSR J1119-6127 is clearly a transition object, i.e. a high-magnetic field neutron star that is normally a rotation-powered pulsar in radio and X-rays, but also shows transient magnetar-like behavior, i.e. behavior unlikely to be powered solely by rotation, but also by release of stored magnetic energy. We will discuss recent results and implications for understanding the emission behavior of high magnetic field pulsars.This research was performed at the Jet Propulsion Laboratory, California Institute of Technology, under the Research and Technology Development Program, under a contract with the National Aeronautics and Space Administration.

  3. Radio Pulsar Death Line Revisited Is PSR J2144-3933 Anomalous?

    CERN Document Server

    Zhang, B; Muslimov, A G; Zhang, Bing; Harding, Alice K.; Muslimov, Alexander G.

    2000-01-01

    We reinvestigate the radio pulsar ``death lines'' within the framework of two different types of polar cap acceleration models, i.e., the vacuum gap model and the space-charge-limited flow model, with either curvature radiation or inverse Compton scattering photons as the source of pairs. General relativistic frame-dragging is taken into account in both models. We find that the inverse Compton scattering induced space-charge-limited flow model can sustain strong pair production in some long-period pulsars, which allows the newly detected 8.5s pulsar PSR J2144-3933 to be radio loud, without assuming a special neutron star equation-of-state or ad hoc magnetic field configurations.

  4. Chandra observations of the elusive pulsar wind nebula around PSR B0656+14

    CERN Document Server

    Bîrzan, L; Kargaltsev, O

    2015-01-01

    PSR B0656+14 is a middle-aged pulsar with a characteristic age $\\tau_c=110$ kyr and spin-down power $\\dot{E}= 3.8\\times 10^{34}$ erg s$^{-1}$. Using Chandra data, we searched for a pulsar wind nebula (PWN) and found evidence of extended emission in a 3.5-15 arcsec annulus around the pulsar, with a luminosity $L_{\\rm 0.5-8\\,keV}^{\\rm ext} \\sim 8\\times 10^{28}$ erg s$^{-1}$ (at the distance of 288 pc), which is a fraction of $\\sim 0.05$ of the non-thermal pulsar luminosity. If the extended emission is mostly due to a PWN, its X-ray efficiency, $\\eta_{\\rm pwn} = L_{\\rm 0.5-8\\,keV}^{\\rm ext}/\\dot{E} \\sim 2\\times 10^{-6}$, is lower than those of most other known PWNe but similar to that of the middle-aged Geminga pulsar. The small radial extent and nearly round shape of the putative PWN can be explained if the pulsar is receding (or approaching) in the direction close to the line of sight. The very soft spectrum of the extended emission ($\\Gamma\\sim 8$), much softer than those of typical PWNe, could be explained b...

  5. PSR J1723-2837: An Eclipsing Binary Radio Millisecond Pulsar

    CERN Document Server

    Crawford, F; Stairs, I H; Kaplan, D L; McLaughlin, M A; Freire, P C C; Burgay, M; Camilo, F; D'Amico, N; Faulkner, A; Kramer, M; Lorimer, D R; Manchester, R N; Possenti, A; Steeghs, D

    2013-01-01

    We present a study of PSR J1723-2837, an eclipsing, 1.86 ms millisecond binary radio pulsar discovered in the Parkes Multibeam survey. Radio timing indicates that the pulsar has a circular orbit with a 15 hr orbital period, a low-mass companion, and a measurable orbital period derivative. The eclipse fraction of ~15% during the pulsar's orbit is twice the Roche lobe size inferred for the companion. The timing behavior is significantly affected by unmodeled systematics of astrophysical origin, and higher-order orbital period derivatives are needed in the timing solution to account for these variations. We have identified the pulsar's (non-degenerate) companion using archival ultraviolet, optical, and infrared survey data and new optical photometry. Doppler shifts from optical spectroscopy confirm the star's association with the pulsar and indicate a pulsar-to-companion mass ratio of 3.3 +/- 0.5, corresponding to a companion mass range of 0.4 to 0.7 Msun and an orbital inclination angle range of between 30 and ...

  6. PSR J1738+0333: The First Millisecond Pulsar + Pulsating White Dwarf Binary

    CERN Document Server

    Kilic, Mukremin; Gianninas, A; Brown, Warren R

    2014-01-01

    We report the discovery of the first millisecond pulsar with a pulsating white dwarf companion. Following the recent discoveries of pulsations in extremely low-mass (ELM, <0.3 Msol) white dwarfs (WDs), we targeted ELM WD companions to two millisecond pulsars with high-speed Gemini photometry. We find significant optical variability in PSR J1738+0333 with periods between roughly 1790-3060 s, consistent in timescale with theoretical and empirical observations of pulsations in 0.17 Msol He-core ELM WDs. We additionally put stringent limits on a lack of variability in PSR J1909-3744, showing this ELM WD is not variable to <0.1 per cent amplitude. Thanks to the accurate distance and radius estimates from radio timing measurements, PSR J1738+0333 becomes a benchmark for low-mass, pulsating WDs. Future, more extensive time-series photometry of this system offers an unprecedented opportunity to constrain the physical parameters (including the cooling age) and interior structure of this ELM WD, and in turn, the ...

  7. Constraining the geometry of PSR J0855-4644: A nearby Pulsar Wind Nebula with Double Torus/Jet Morphology

    CERN Document Server

    Maitra, Chandreyee; Venter, Christo

    2016-01-01

    Aims: PSR J0855-4644 is a fast-spinning, energetic pulsar discovered at radio wavelengths near the south-eastern rim of the supernova remnant RX J0852.0-4622. A follow-up observation revealed the pulsar's X-ray counterpart and a slightly asymmetric PWN suggesting possible jet structures. PSR J0855-4644 is a pulsar with one of the highest \\dot{E}/d^{2} from which no GeV \\gamma-ray pulsations have been detected. Methods: With a dedicated Chandra observation, we perform detailed spatial modelling to constrain the geometry of the PWN, in particular the pulsar's line of sight \\zeta_{\\rm PSR}. We also perform geometric radio and \\gamma-ray light curve modelling to further constrain \\zeta_{\\rm PSR} and the magnetic obliquity \\alpha. Results: The observation reveals that the compact XMM source, thought to be the X-ray pulsar, can be further resolved into a point source surrounded by an elongated axisymmetric nebula with a longitudinal extent of 10". The pulsar flux represents only \\sim 1\\% of the XMM compact source a...

  8. PSR J1753-2240: A mildly recycled pulsar in an eccentric binary system

    CERN Document Server

    Keith, M J; Lyne, A G; Eatough, R P; Stairs, I H; Possenti, A; Camilo, F; Manchester, R N

    2008-01-01

    We report the discovery of PSR J1753-2240 in the Parkes Multibeam Pulsar Survey database. This 95-ms pulsar is in an eccentric binary system with a 13.6-day orbital period. Period derivative measurements imply a characteristic age in excess of 1 Gyr, suggesting that the pulsar has undergone an episode of accretion-induced spin-up. The eccentricity and spin period are indicative of the companion being a second neutron star, so that the system is similar to that of PSR J1811-1736, although other companion types cannot be ruled out at this time. The companion mass is constrained by geometry to lie above 0.48 solar masses, although long-term timing observations will give additional constraints. If the companion is a white dwarf or main sequence star, optical observations may yield a direct detection of the companion. If the system is indeed one of the few known double neutron star systems, it would lie significantly far from the recently proposed spin-period/eccentricity relationship.

  9. Jiamusi Pulsar Observations: I. Abnormal emission events of PSR B0919+06

    CERN Document Server

    Han, Jun; Peng, Ling-Xiang; Tang, De-Yu; Wang, Jun; Li, Jun-Qiang; Wang, Chen; Yu, Ye-Zhao; Dong, Bin

    2016-01-01

    PSR B0919+06 generally radiates radio pulses in a normal phase range. It has been known for its occasional perplexing abnormal emission events wherein individual pulses come to an earlier phase range for a few tens of periods and then returns to its usual phase. Heretofore, only a few such events have been available for study. We observed PSR B0919+06 for about 30 hours using the Jiamusi 66-m telescope at Jiamusi Deep Space Station at S-band, and detected 92 abnormal emission events. We identify four types of events based on the abrupted or gradual phase-shifting of individual pulses. The abnormal emission events are seen to occur randomly some every 1000 to 3000 periods, and they affect the leading edge of the mean profile by up to 2\\% in amplitude. The abnormal emission events are probably related to gradual changes of emission processing in the pulsar magnetosphere.

  10. Deep Chandra Observations of the Pulsar Wind Nebula Created by PSR B0355+54

    Science.gov (United States)

    Klingler, Noel; Rangelov, Blagoy; Kargaltsev, Oleg; Pavlov, George G.; Romani, Roger W.; Posselt, Bettina; Slane, Patrick; Temim, Tea; Ng, C.-Y.; Bucciantini, Niccolò; Bykov, Andrei; Swartz, Douglas A.; Buehler, Rolf

    2016-12-01

    We report on Chandra X-ray Observatory (CXO) observations of the pulsar wind nebula (PWN) associated with PSR B0355+54 (eight observations with a 395 ks total exposure, performed over an eight month period). We investigated the spatial and spectral properties of the emission coincident with the pulsar, compact nebula (CN), and extended tail. We find that the CN morphology can be interpreted in a way that suggests a small angle between the pulsar spin axis and our line of sight, as inferred from the radio data. On larger scales, emission from the 7\\prime (≈ 2 pc) tail is clearly seen. We also found hints of two faint extensions nearly orthogonal to the direction of the pulsar’s proper motion. The spectrum extracted at the pulsar position can be described with an absorbed power-law + blackbody model. The nonthermal component can be attributed to magnetospheric emission, while the thermal component can be attributed to emission from either a hot spot (e.g., a polar cap) or the entire neutron star surface. Surprisingly, the spectrum of the tail shows only a slight hint of cooling with increasing distance from the pulsar. This implies either a low magnetic field with fast flow speed, or particle reacceleration within the tail. We estimate physical properties of the PWN and compare the morphologies of the CN and the extended tail with those of other bow shock PWNe observed with long CXO exposures.

  11. Deep Chandra Observations of the Pulsar Wind Nebula Created by PSR B0355+54

    CERN Document Server

    Klingler, Noel; Kargaltsev, Oleg; Pavlov, George G; Romani, Roger W; Posselt, Bettina; Slane, Patrick; Temim, Tea; Ng, C -Y; Bucciantini, Niccolò; Bykov, Andrei; Swartz, Douglas A; Buehler, Rolf

    2016-01-01

    We report on Chandra X-ray Observatory (CXO) observations of the pulsar wind nebula (PWN) associated with PSR B0355+54 (eight observations with a 395 ks total exposure, performed over an 8 month period). We investigated the spatial and spectral properties of the emission coincident with the pulsar, compact nebula (CN), and extended tail. We find that the CN morphology can be interpreted in a way that suggests a small angle between the pulsar spin axis and our line-of-sight, as inferred from the radio data. On larger scales, emission from the 7' (2 pc) tail is clearly seen. We also found hints of two faint extensions nearly orthogonal to the direction of the pulsar's proper motion. The spectrum extracted at the pulsar position can be described with an absorbed power-law + blackbody model. The nonthermal component can be attributed to magnetospheric emission, while the thermal component can be attributed to emission from either a hot spot (e.g., a polar cap) or the entire neutron star surface. Surprisingly, the...

  12. Properties and Evolution of the Redback Millisecond Pulsar Binary PSR J2129-0429

    CERN Document Server

    Bellm, Eric C; Breton, Rene P; Phinney, E Sterl; Bhalerao, Varun B; Camilo, Fernando; Dahal, Sumit; Djorgovski, S G; Drake, Andrew J; Hessels, J W T; Laher, Russ R; Levitan, David B; Lewis, Fraser; Mahabal, Ashish A; Ofek, Eran O; Prince, Thomas A; Ransom, Scott M; Roberts, Mallory S E; Russell, David M; Sesar, Branimir; Surace, Jason A; Tang, Sumin

    2015-01-01

    PSR J2129-0429 is a "redback" eclipsing millisecond pulsar binary with an unusually long 15.2 hour orbit. It was discovered by the Green Bank Telescope in a targeted search of unidentified Fermi gamma-ray sources. The pulsar companion is optically bright (mean $m_R = 16.6$ mag), allowing us to construct the longest baseline photometric dataset available for such a system. We present ten years of archival and new photometry of the companion from LINEAR, CRTS, PTF, the Palomar 60-inch, and LCOGT. Radial velocity spectroscopy using the Double-Beam Spectrograph on the Palomar 200-inch indicates that the pulsar is massive: $1.74\\pm0.18 M_\\odot$. The G-type pulsar companion has mass $0.44\\pm0.04 M_\\odot$, one of the heaviest known redback companions. It is currently 95\\% Roche-lobe filling and only mildly irradiated by the pulsar. We identify a clear 13.1 mmag yr$^{-1}$ secular decline in the mean magnitude of the companion as well as smaller-scale variations in the optical lightcurve shape. This behavior may indic...

  13. Fermi LAT Detection of Pulsed Gamma-Rays From the Vela-Like Pulsars PSR J1048-5832 and PSR J2229+6114

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A.A.; /Naval Research Lab, Wash., D.C. /Federal City Coll.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ajello, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M.; /Stockholm U. /Stockholm U., OKC; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, G.; /INFN, Trieste /Trieste U.; Baring, M.G.; /Rice U.; Bastieri, D.; /INFN, Padua /Padua U.; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, E.D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Columbia U. /IASF, Milan /Milan Polytechnic /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Naval Research Lab, Wash., D.C. /George Mason U. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /LPCE, Orleans /Montpellier U. /Stockholm U. /Stockholm U., OKC /INFN, Trieste /Bari U. /INFN, Bari /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Montpellier U. /Bari U. /INFN, Bari /INFN, Trieste /Arecibo Observ. /Hiroshima U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Bari U. /INFN, Bari /INFN, Bari /NASA, Goddard /Maryland U. /INFN, Perugia /Perugia U.; /more authors..

    2012-03-29

    We report the detection of {gamma}-ray pulsations ({ge}0.1 GeV) from PSR J2229+6114 and PSR J1048-5832, the latter having been detected as a low-significance pulsar by EGRET. Data in the {gamma}-ray band were acquired by the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope, while the radio rotational ephemerides used to fold the {gamma}-ray light curves were obtained using the Green Bank Telescope, the Lovell telescope at Jodrell Bank, and the Parkes Telescope. The two young radio pulsars, located within the error circles of the previously unidentified EGRET sources 3EG J1048-5840 and 3EG J2227+6122, present spin-down characteristics similar to the Vela pulsar. PSR J1048-5832 shows two sharp peaks at phases 0.15 {+-} 0.01 and 0.57 {+-} 0.01 relative to the radio pulse confirming the EGRET light curve, while PSR J2229+6114 presents a very broad peak at phase 0.49 {+-} 0.01. The {gamma}-ray spectra above 0.1 GeV of both pulsars are fit with power laws having exponential cutoffs near 3 GeV, leading to integral photon fluxes of (2.19 {+-} 0.22 {+-} 0.32) x 10{sup -7} cm{sup -2} s{sup -1} for PSR J1048-5832 and (3.77 {+-} 0.22 {+-} 0.44) x 10{sup -7} cm{sup -2} s{sup -1} for PSR J2229+6114. The first uncertainty is statistical and the second is systematic. PSR J1048-5832 is one of the two LAT sources which were entangled together as 3EG J1048-5840. These detections add to the growing number of young {gamma}-ray pulsars that make up the dominant population of GeV {gamma}-ray sources in the Galactic plane.

  14. Spitzer MIPS Limits on Asteroidal Dust in the Pulsar Planetary System PSR B1257+12

    Science.gov (United States)

    Bryden, G.; Beichman, C. A.; Rieke, G. H.; Stansberry, J. A.; Stapelfeldt, K. R.; Trilling, D. E.; Turner, N. J.; Wolszczan, A.

    2006-01-01

    With the MIPS camera on Spitzer, we have searched for far-infrared emission from dust in the planetary system orbiting pulsar PSR B1257+12. With accuracies of 0.05 mJy at 24 microns and 1.5 mJy at 70 microns, photometric measurements find no evidence for emission at these wavelengths. These observations place new upper limits on the luminosity of dust with temperatures between 20 and 1000 K. They are particularly sensitive to dust temperatures of 100-200 K, for which they limit the dust luminosity to below 3 x 10(exp -5) of the pulsar's spin-down luminosity, 3 orders of magnitude better than previous limits. Despite these improved constraints on dust emission, an asteroid belt similar to the solar system's cannot be ruled out.

  15. Exploring the intrabinary shock from the redback millisecond pulsar PSR J2129-0429

    CERN Document Server

    Hui, C Y; Park, S M; Takata, J; Li, K L; Tam, P H T; Lin, L C C; Kong, A K H; Cheng, K S; Kim, Chunglee

    2015-01-01

    We have investigated the intrabinary shock emission from the redback millisecond pulsar PSR J2129-0429 with XMM-Newton and Fermi. Orbital modulation in X-ray and UV can be clearly seen. Its X-ray modulation has a double-peak structure with a dip in between. The observed X-rays are non-thermal dominant which can be modeled by a power-law with a photon index of ~1.2. Intrabinary shock can be the origin of the observed X-rays. The UV light curve is resulted from the ellipsoidal modulation of the companion. Modeling the UV light curve prefers a large viewing angle. The heating effect of the UV light curve is found to be negligible which suggests the high energy radiation beam of PSR J2129-0429 does not direct toward its companion. On the other hand, no significant orbital modulation can be found in gamma-ray which suggests the majority of the gamma-rays come from the pulsar.

  16. Location of the emitting regions in the mode-switching radio pulsar PSR 1926 + 18

    Science.gov (United States)

    Nowakowski, L. A.

    1994-01-01

    We present an analysis of average single-frequency profiles of the radio pulsar PSR 1926 + 18 in two different modes. Assuming a purely dipolar field and taking into account retardation, aberration, magnetic line curvature, and ignoring the magnetic field line sweepback, we come to the following conclusions: (1) mode switching in PSR 1926 + 18 at 430 MHz may be understood in terms of different emission heights of the two modes; (2) the weaker mode appears when regions emitting the first two components move away from the star by an additional distance of not more than several kilometers from their original locations; (3) the trailing conal component is emitted essentially from the same layer of the magnetosphere in both modes, in contrast to the first conal component, which appears to change its location in the magnetosphere; (4) core and conal components are emitted from distinctly different emission heights: core components not more than 75 km, and conal components not less than 215 km from the surface of the star. Our model infers three-dimensional information about the emitting region from single-frequency observations. It has been tested previously with a mode switching pulsar that had one component in the average profile in two modes. This paper shows that the same model can explain positions and widths of the components in a more complex profile during mode switching, provided that the components can be traced from one mode to another.

  17. PSR J1833-1034, the Very Young Pulsar in SNR G21.5-0.9

    Science.gov (United States)

    Camilo, Fernando; Gaensler, Bryan; Manchester, Dick; Ransom, Scott; Lorimer, Duncan Ross

    2007-04-01

    We have been timing the very young pulsar PSR J1833-1034, recently discovered near the center of the supernova remnant (SNR) G21.5-0.9 (Camilo et al. 2006). With 16 months of timing data in hand we have confirmed that the pulsar is coincident, to sub-arcsec precision, with the centrally-peaked X-ray source visible in Chandra data near the center of G21.5-0.9 and have therefore confirmed this pulsar-SNR association beyond any doubt. More unexpectedly, we have been able to measure this pulsar's braking index, n = 2.18, only the 6th such phase-coherent measurement done in over 1700 pulsars known. We now have a chance to measure the "second braking index" and place further constraints on the spin-down law obeyed by this pulsar. This has been done to date for only 2 pulsars. Finally, we wish to continue timing this pulsar because it will be one of the prime candidates for gamma-ray detection with the GLAST satellite to be launched in 2007, and in order to do so we must maintain its timing solution. For these reasons we request 24 hr for timing PSR J1833-1034 during the present semester.

  18. Discovery of the Millisecond Pulsar PSR J2043+1711 in a Fermi Source with the Nancay Radio Telescope

    Science.gov (United States)

    Guillemot, L.; Freire, P. C. C.; Cognard, I.; Johnson, T. J.; Takahashi, Y.; Kataoka, J.; Desvignes, G.; Camilo, F.; Ferrara, E. C.; Harding, A. K.; hide

    2012-01-01

    We report the discovery of the millisecond pulsar PSR J2043+1711 in a search of a Fermi Large Area Telescope (LAT) source with no known associations, with the Nancay Radio Telescope. The new pulsar, confirmed with the Green Bank Telescope, has a spin period of 2.38 ms, is relatively nearby (d approx. system have made PSR J2043+1711 one of the first new Fermi-selected millisecond pulsars to be added to pulsar gravitational wave timing arrays. It has also allowed a significant measurement of relativistic delays in the times of arrival of the pulses due to the curvature of space-time near the companion, but not yet with enough precision to derive useful masses for the pulsar and the companion. Nevertheless, a mass for the pulsar between 1.7 and 2.0 solar Mass can be derived if a standard millisecond pulsar formation model is assumed. In this paper, we also present a comprehensive summary of pulsar searches in Fermi LAT sources with the Nancay Radio Telescope to date.

  19. X-ray and γ-ray studies of the millisecond pulsar and possible X-ray binary/radio pulsar transition object PSR J1723-2837

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Esposito, Paolo [INAF-IASF Milano, via East Bassini 15, I-20133 Milano (Italy); Crawford III, Fronefield [Department of Physics and Astronomy, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604 (United States); Possenti, Andrea [INAF-Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, I-09012 Capoterra (Italy); McLaughlin, Maura A. [Department of Physics and Astronomy, West Virginia University, 210E Hodges Hall, Morgantown, WV 26506 (United States); Freire, Paulo, E-mail: slavko@astro.columbia.edu [Max-Planck-Institut für Radioastronomie, D-53121 Bonn (Germany)

    2014-01-20

    We present X-ray observations of the 'redback' eclipsing radio millisecond pulsar (MSP) and candidate radio pulsar/X-ray binary transition object PSR J1723-2837. The X-ray emission from the system is predominantly non-thermal and exhibits pronounced variability as a function of orbital phase, with a factor of ∼2 reduction in brightness around superior conjunction. Such temporal behavior appears to be a defining characteristic of this variety of peculiar MSP binaries and is likely caused by a partial geometric occultation by the main-sequence-like companion of a shock within the binary. There is no indication of diffuse X-ray emission from a bow shock or pulsar wind nebula associated with the pulsar. We also report on a search for point source emission and γ-ray pulsations in Fermi Large Area Telescope data using a likelihood analysis and photon probability weighting. Although PSR J1723-2837 is consistent with being a γ-ray point source, due to the strong Galactic diffuse emission at its position a definitive association cannot be established. No statistically significant pulsations or modulation at the orbital period are detected. For a presumed detection, the implied γ-ray luminosity is ≲5% of its spin-down power. This indicates that PSR J1723-2837 is either one of the least efficient γ-ray producing MSPs or, if the detection is spurious, the γ-ray emission pattern is not directed toward us.

  20. Simultaneous X-ray and radio observations of the radio-mode-switching pulsar PSR B1822-09

    Science.gov (United States)

    Hermsen, W.; Kuiper, L.; Hessels, J. W. T.; Mitra, D.; Rankin, J. M.; Stappers, B. W.; Wright, G. A. E.; Basu, R.; Szary, A.; van Leeuwen, J.

    2017-04-01

    We report on simultaneous X-ray and radio observations of the radio-mode-switching pulsar PSR B1822-09 with ESA's XMM-Newton and the Westerbork Synthesis Radio Telescope, Giant Metrewave Radio Telescope and Lovell radio telescopes. PSR B1822-09 switches between a radio-bright and radio-quiet mode, and we discovered a relationship between the durations of its modes and a known underlying radio-modulation time-scale within the modes. We discovered X-ray (energies 0.2-1.4 keV) pulsations with a broad sinusoidal pulse, slightly lagging the radio main pulse in phase by 0.094 ± 0.017, with an energy-dependent pulsed fraction varying from ∼0.15 at 0.3 keV to ∼0.6 at 1 keV. No evidence is found for simultaneous X-ray and radio mode switching. The total X-ray spectrum consists of a cool component (T ∼0.96 × 106 K, hotspot radius R ∼2.0 km) and a hot component (T ∼2.2 × 106 K, R ∼100 m). The hot component can be ascribed to the pulsed emission and the cool component to the unpulsed emission. The high-energy characteristics of PSR B1822-09 resemble those of middle-aged pulsars such as PSR B0656+14, PSR B1055-52 and Geminga, including an indication for pulsed high-energy gamma-ray emission in Fermi Large Area Telescope data. Explanations for the high pulsed fraction seem to require different temperatures at the two poles of this orthogonal rotator, or magnetic anisotropic beaming effects in its strong magnetic field. In our X-ray skymap, we found a harder source at only 5.1 ± 0.5 arcsec from PSR B1822-09, which might be a pulsar wind nebula.

  1. Broadband pulsations from PSR B1821–24: Implications for emission models and the pulsar population of M28

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, T. J. [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); Guillemot, L.; Freire, P. C. C. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Kerr, M.; Romani, R. W.; Wood, M. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement, LPCE UMR 6115 CNRS, F-45071 Orléans Cedex 02 (France); Ray, P. S.; Wolff, M. T.; Grove, J. E.; Cheung, C. C. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Bégin, S. [Département de physique, génie physique et optique, Université Laval, Québec (Canada); Janssen, G. H.; Espinoza, C. M. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Venter, C. [Centre for Space Research, North-West University, Potchefstroom Campus, Private Bag X6001, 2520 Potchefstroom (South Africa); Casandjian, J. M. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d' Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Ferrara, E. C.; Harding, A. K., E-mail: tyrel.j.johnson@gmail.com, E-mail: guillemo@mpifr-bonn.mpg.de, E-mail: kerrm@stanford.edu, E-mail: icognard@cnrs-orleans.fr, E-mail: Paul.Ray@nrl.navy.mil [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); and others

    2013-12-01

    We report a 5.4σ detection of pulsed gamma rays from PSR B1821–24 in the globular cluster M28 using ∼44 months of Fermi Large Area Telescope (LAT) data that have been reprocessed with improved instrument calibration constants. We constructed a phase-coherent ephemeris, with post-fit residual rms of 3 μs, using radio data spanning ∼23.2 yr, enabling measurements of the multi-wavelength light-curve properties of PSR B1821–24 at the milliperiod level. We fold RXTE observations of PSR B1821–24 from 1996 to 2007 and discuss implications on the emission zones. The gamma-ray light curve consists of two peaks separated by 0.41 ± 0.02 in phase, with the first gamma-ray peak lagging behind the first radio peak by 0.05 ± 0.02 in phase, consistent with the phase of giant radio pulses. We observe significant emission in the off-peak interval of PSR B1821–24 with a best-fit LAT position inconsistent with the core of M28. We do not detect significant gamma-ray pulsations at the spin or orbital periods from any other known pulsar in M28, and we place limits on the number of energetic pulsars in the cluster. The derived gamma-ray efficiency, ∼2%, is typical of other gamma-ray pulsars with comparable spin-down power, suggesting that the measured spin-down rate (2.2 × 10{sup 36} erg s{sup –1}) is not appreciably distorted by acceleration in the cluster potential. This confirms PSR B1821–24 as the second very energetic millisecond pulsar in a globular cluster and raises the question of whether these represent a separate class of objects that only form in regions of very high stellar density.

  2. SCINTILLATION ARCS IN LOW-FREQUENCY OBSERVATIONS OF THE TIMING-ARRAY MILLISECOND PULSAR PSR J0437–4715

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, N. D. R.; Ord, S. M.; Tremblay, S. E.; McSweeney, S. J.; Tingay, S. J. [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia)

    2016-02-10

    Low-frequency observations of pulsars provide a powerful means for probing the microstructure in the turbulent interstellar medium (ISM). Here we report on high-resolution dynamic spectral analysis of our observations of the timing-array millisecond pulsar PSR J0437–4715 with the Murchison Widefield Array (MWA), enabled by our recently commissioned tied-array beam processing pipeline for voltage data recorded from the high time resolution mode of the MWA. A secondary spectral analysis reveals faint parabolic arcs akin to those seen in high-frequency observations of pulsars with the Green Bank and Arecibo telescopes. Data from Parkes observations at a higher frequency of 732 MHz reveal a similar parabolic feature with a curvature that scales approximately as the square of the observing wavelength (λ{sup 2}) to the MWA's frequency of 192 MHz. Our analysis suggests that scattering toward PSR J0437–4715 predominantly arises from a compact region about 115 pc from the Earth, which matches well with the expected location of the edge of the Local Bubble that envelopes the local Solar neighborhood. As well as demonstrating new and improved pulsar science capabilities of the MWA, our analysis underscores the potential of low-frequency pulsar observations for gaining valuable insights into the local ISM and for characterizing the ISM toward timing-array pulsars.

  3. NuSTAR observations of the young, energetic radio pulsar PSR B1509-58

    CERN Document Server

    Chen, Ge; Kaspi, Victoria M; Harrison, Fiona; Madsen, Kristen; Stern, Daniel

    2015-01-01

    We report on Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of the young rotation-powered radio pulsar PSR B1509$-$58 in the supernova remnant MSH 15$-$52. We confirm the previously reported curvature in the hard X-ray spectrum, showing that a log parabolic model provides a statistically superior fit to the spectrum compared with the standard power law. The log parabolic model describes the NuSTAR data, as well as previously published gamma-ray data obtained with COMPTEL and AGILE, all together spanning 3 keV through 500 MeV. Our spectral modelling allows us to constrain the peak of the broadband high energy spectrum to be at 2.6$\\pm$0.8 MeV, an improvement of nearly an order of magnitude over previous measurements. In addition, we calculate NuSTAR spectra in 26 pulse phase bins and confirm previously reported variations of photon indices with phase. Finally, we measure the pulsed fraction of PSR B1509$-$58 in the hard X-ray energy band for the first time. Using the energy resolved pul...

  4. A candidate optical counterpart to the middle-aged gamma-ray pulsar PSR J1741-2054

    CERN Document Server

    Mignani, R P; Marelli, M; De Luca, A; Salvetti, D; Belfiore, A; Pierbattista, M; Razzano, M; Shearer, A; Moran, P

    2016-01-01

    We carried out deep optical observations of the middle-aged $\\gamma$-ray pulsar PSR J1741-2054 with the Very Large Telescope (VLT). We identified two objects, of magnitudes $m_v=23.10\\pm0.05$ and $m_v=25.32\\pm0.08$, at positions consistent with the very accurate Chandra coordinates of the pulsar, the faintest of which is more likely to be its counterpart. From the VLT images we also detected the known bow-shock nebula around PSR J1741-2054. The nebula is displaced by $\\sim 0\\farcs9$ (at the $3\\sigma$ confidence level) with respect to its position measured in archival data, showing that the shock propagates in the interstellar medium consistently with the pulsar proper motion. Finally, we could not find evidence of large-scale extended optical emission associated with the pulsar wind nebula detected by Chandra, down to a surface brightness limit of $\\sim 28.1$ magnitudes arcsec$^{-2}$. Future observations are needed to confirm the optical identification of PSR J1741-2054 and characterise the spectrum of its co...

  5. LMXB and IMXB Evolution: I. The Binary Radio Pulsar PSR J1614-2230

    CERN Document Server

    Lin, Jinrong; Podsiadlowski, Ph; Nelson, L; Paxton, B; Todorov, P

    2010-01-01

    We have computed an extensive grid of binary evolution tracks to represent low- and intermediate mass X-ray binaries (LMXBs and IMXBs). The grid includes 42,000 models which covers 60 initial donor masses over the range of 1-4 solar masses and, for each of these, 700 initial orbital periods over the range of 10-250 hours. These results can be applied to understanding LMXBs and IMXBs: those that evolve analogously to CVs; those that form ultracompact binaries with orbital periods in the range of 6-50 minutes; and those that lead to wide orbits with giant donors. We also investigate the relic binary recycled radio pulsars into which these systems evolve. To evolve the donor stars in this study, we utilized a newly developed stellar evolution code called "MESA" that was designed, among other things, to be able to handle very low-mass and degenerate donors. This first application of the results is aimed at an understanding of the newly discovered pulsar PSR J1614-2230 which has a 1.97 solar masses neutron star, o...

  6. Gravitational-radiation losses from the pulsar-white-dwarf binary PSR J1141-6545

    CERN Document Server

    Bhat, N D Ramesh; Verbiest, Joris P W

    2008-01-01

    Pulsars in close binary orbit around another neutron star or a massive white dwarf make ideal laboratories for testing the predictions of gravitational radiation and self-gravitational effects. We report new timing measurements of the pulsar-white-dwarf binary PSR J1141-6545, providing strong evidence that such asymmetric systems have gravitational wave losses that are consistent with general relativity. The orbit is found to be decaying at a rate of $1.04\\pm0.06$ times the general relativistic prediction and the Shapiro delay is consistent with the orbital inclination angle derived from scintillation measurements. The system provides a unique test-bed for tensor-scalar theories of gravity; our current measurements place stringent constraints in the theory space, with a limit of $\\alpha_0^2 < 2.1 \\times 10^{-5}$ for weakly non-linear coupling and an asymptotic limit of $\\alpha_0^2 < 3.4 \\times 10^{-6}$ for strongly non-linear coupling, where $\\alpha_0$ is the linear coupling strength of matter to an und...

  7. Relativistic Measurements from Timing the Binary Pulsar PSR B1913+16

    CERN Document Server

    Weisberg, Joel M

    2016-01-01

    We present relativistic analyses of 9257 measurements of times-of-arrival from the first binary pulsar, PSR B1913+16, acquired over the last thirty-five years. The determination of the 'Keplerian' orbital elements plus two relativistic terms completely characterizes the binary system, aside from an unknown rotation about the line of sight; leading to a determination of the masses of the pulsar and its companion: 1.438 $\\pm$ 0.001 solar masses and 1.390 $\\pm$ 0.001 solar masses, respectively. In addition, the complete system characterization allows the creation of tests of relativistic gravitation by comparing measured and predicted sizes of various relativistic phenomena. We find that the ratio of observed orbital period decrease due to gravitational wave damping (corrected by a kinematic term) to the general relativistic prediction, is 0.9983 pm 0.0016; thereby confirming the existence and strength of gravitational radiation as predicted by general relativity. For the first time in this system, we have also ...

  8. The Near-UV Pulse Profile and Spectrum of the Pulsar PSR B0656+14

    CERN Document Server

    Shibanov, Y A; Lundqvist, P; Gull, T R; Lindler, D; Shibanov, Yu.A.

    2005-01-01

    We have observed the middle-aged pulsar PSR B0656+14 with the prism and the NUV MAMA detector of the Space Telescope Imaging Spectrograph (STIS) to measure the pulsar spectrum and periodic pulsations in the near-ultraviolet (NUV). The pulsations are clearly detected, double-peaked and very similar to the optical pulse profile. The NUV pulsed fraction is 70 +/- 12%. The spectral slope of the dereddened phase-integrated spectrum in the 1800 - 3200 A range is 0.35 +/- 0.5 which together with the high pulse fraction indicates a non-thermal origin for the NUV emission. The total flux in the range 1700-3400 A is estimated to be 3.4 +/- 0.3e-15 erg/s/cm2 when corrected for E(B-V)=0.03. At a distance of 288 pc this corresponds to a luminosity 3.4e28 erg/s assuming isotropy of the emission. We compare the NUV pulse profile with observations from radio to gamma-rays. The first NUV sub-pulse is in phase with the gamma-ray pulse marginally detected with the EGRET, while the second NUV sub-pulse is similar both in shape a...

  9. PsrPopPy: An open-source package for pulsar population simulations

    CERN Document Server

    Bates, Sam; Rane, Akshaya; Swiggum, Joe

    2013-01-01

    We have produced a new software package for the simulation of pulsar populations, \\textsc{PsrPopPy}, based on the \\textsc{Psrpop} package. The codebase has been re-written in Python (save for some external libraries, which remain in their native Fortran), utilising the object-oriented features of the language, and improving the modularity of the code. Pre-written scripts are provided for running the simulations in `standard' modes of operation, but the code is flexible enough to support the writing of personalised scripts. The modular structure also makes the addition of experimental features (such as new models for period or luminosity distributions) more straightforward than with the previous code. We also discuss potential additions to the modelling capabilities of the software. Finally, we demonstrate some potential applications of the code; first, using results of surveys at different observing frequencies, we find pulsar spectral indices are best fit by a normal distribution with mean $-1.4$ and standar...

  10. X-ray and $\\gamma$-ray Studies of the Millisecond Pulsar and PossibleX-ray Binary/Radio Pulsar Transition Object PSR J1723-2837

    CERN Document Server

    Bogdanov, Slavko; Crawford, Fronefield; Possenti, Andrea; McLaughlin, Maura A; Freire, Paulo

    2013-01-01

    We present X-ray observations of the ``redback'' eclipsing radio millisecond pulsar and candidate radio pulsar/X-ray binary transition object PSR J1723-2837. The X-ray emission from the system is predominantly non-thermal and exhibits pronounced variability as a function of orbital phase, with a factor of ~2 reduction in brightness around superior conjunction. Such temporal behavior appears to be a defining characteristic of this variety of peculiar millisecond pulsar binaries and is likely caused by a partial geometric occultation by the main-sequence-like companion of a shock within the binary. There is no indication of diffuse X-ray emission from a bow shock or pulsar wind nebula associated with the pulsar. We also report on a search for point source emission and $\\gamma$-ray pulsations in Fermi Large Area Telescope data using a likelihood analysis and photon probability weighting. Although PSR J1723-2837 is consistent with being a $\\gamma$-ray point source, due to the strong Galactic diffuse emission at i...

  11. The Massive Pulsar PSR J1614-2230: Linking Quantum Chromodynamics, Gamma-ray Bursts, and Gravitational Wave Astronomy

    OpenAIRE

    Ozel, Feryal; Psaltis, Dimitrios; Ransom, Scott; Demorest, Paul; Alford, Mark

    2010-01-01

    The recent measurement of the Shapiro delay in the radio pulsar PSR J1614-2230 yielded a mass of 1.97 +/- 0.04 M_sun, making it the most massive pulsar known to date. Its mass is high enough that, even without an accompanying measurement of the stellar radius, it has a strong impact on our understanding of nuclear matter, gamma-ray bursts, and the generation of gravitational waves from coalescing neutron stars. This single high mass value indicates that a transition to quark matter in neutron...

  12. Observations of the Pulsar PSR B1951+32 with the Solar Tower Atmospheric Cherenkov Effect Experiment

    CERN Document Server

    Kildea, J; Ball, J; Carson, J E; Covault, C E; Driscoll, D D; Fortin, P; Gingrich, D M; Hanna, D S; Jarvis, A; Lindner, T; Müller, C; Mukherjee, R; Ong, R A; Ragan, K; Williams, D A

    2007-01-01

    We present the analysis and results of 12.5 hours of high-energy gamma-ray observations of the EGRET-detected pulsar PSR B1951+32 using the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE). STACEE is an atmospheric Cherenkov detector, in Albuquerque, New Mexico, that detects cosmic gamma rays using the shower-front-sampling technique. STACEE's sensitivity to astrophysical sources at energies around 100 GeV allows it to investigate emission from gamma-ray pulsars with expected pulsed emission cutoffs below 100 GeV. We discuss the observations and analysis of STACEE's PSR 1951+32 data, accumulated during the 2005 and 2006 observing seasons.

  13. Low Frequency Radio Emission of Pulsar PSR J1907+0919 Associated with the Magnetar SGR 1900+14

    CERN Document Server

    Shitov, Yu P; Kutuzov, S M; Shitov, Yu. P.

    2000-01-01

    The soft gamma repeater SGR 1900+14 was observed in Pushchino observatorysince 1988 December using BSA radio telescope operating at 111 MHz. We havedetected the pulsed radio emission (Shitov 1999) with the same 5.16 s periodthat was reported earlier for this object. The timing analysis has shown thatthis new radio pulsar PSR J1907+0919 associated with SGR 1900+14 has asuperstrong magnetic field, which is 8.1 * 10^14 G, thereby confirming that itis a "magnetar". The dispersion measure of PSR J1907+0919 is 281.4(9) pc *cm^(-3) which gives an estimate of the pulsar's distance as about 5.8 kpc.

  14. Magnetar-like X-Ray Bursts from a Rotation-powered Pulsar, PSR J1119-6127

    Science.gov (United States)

    Göğüş, Ersin; Lin, Lin; Kaneko, Yuki; Kouveliotou, Chryssa; Watts, Anna L.; Chakraborty, Manoneeta; Alpar, M. Ali; Huppenkothen, Daniela; Roberts, Oliver J.; Younes, George; van der Horst, Alexander J.

    2016-10-01

    Two energetic hard X-ray bursts from the rotation-powered pulsar PSR J1119-6127 recently triggered the Fermi and Swift space observatories. We have performed in-depth spectral and temporal analyses of these two events. Our extensive searches in both observatories’ data for lower luminosity bursts uncovered 10 additional events from the source. We report here on the timing and energetics of the 12 bursts from PSR J1119-6127 during its burst active phase on 2016 July 26 and 28. We also found a spectral softer X-ray flux enhancement in a post-burst episode, which shows evidence of cooling. Here we discuss the implications of these results on the nature of this unusual high-field radio pulsar, which firmly place it within the typical magnetar population.

  15. Unusual Pulsed X-Ray Emission from the Young, High Magnetic Field Pulsar PSR J1119--6127

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, M E; Kaspi, V M; Camilo, F; Gaensler, B M; Pivovaroff, M J

    2005-08-05

    We present XMM-Newton observations of the radio pulsar PSR J1119-6127, which has an inferred age of 1,700 yr and surface dipole magnetic field strength of 4.1 x 10{sup 13} G. We report the first detection of pulsed X-ray emission from PSR J1119-6127. In the 0.5-2.0 keV range, the pulse profile shows a narrow peak with a very high pulsed fraction of (74 {+-} 14)%. In the 2.0-10.0 keV range, the upper limit for the pulsed fraction is 28% (99% confidence). The pulsed emission is well described by a thermal blackbody model with a temperature of T{infinity} = 2.4{sub -0.2}{sup +0.3} x 10{sup 6} K and emitting radius of 3.4{sub -0.3}{sup +1.8} km (at a distance of 8.4 kpc). Atmospheric models result in problematic estimates for the distance/emitting area. PSR J1119-6127 is now the radio pulsar with smallest characteristic age from which thermal X-ray emission has been detected. The combined temporal and spectral characteristics of this emission are unlike those of other radio pulsars detected at X-ray energies and challenge current models of thermal emission from neutron stars.

  16. PSR J0357+3205: a fast moving pulsar with a very unusual X-ray trail

    CERN Document Server

    De Luca, A; Marelli, M; Salvetti, D; Sartore, N; Belfiore, A; Parkinson, P Saz; Caraveo, P A; Bignami, G F

    2013-01-01

    The middle-aged PSR J0357+3205 is a nearby, radio-quiet, bright gamma-ray pulsar discovered by the Fermi mission. Our previous Chandra observation revealed a huge, very peculiar structure of diffuse X-ray emission, originating at the pulsar position and extending for > 9' on the plane of the sky. To better understand the nature of such a nebula, we have studied the proper motion of the parent pulsar. We performed relative astrometry on Chandra images of the field spanning a time baseline of 2.2 yr, unveiling a significant angular displacement of the pulsar counterpart, corresponding to a proper motion of 0.165"+/-0.030" yr^(-1). At a distance of ~500 pc, the space velocity of the pulsar would be of ~390 km s^(-1) assuming no inclination with respect to the plane of the sky. The direction of the pulsar proper motion is perfectly aligned with the main axis of the X-ray nebula, pointing to a physical, yet elusive link between the nebula and the pulsar space velocity. No optical emission in the H_alpha line is se...

  17. NUSTAR OBSERVATIONS OF THE YOUNG, ENERGETIC RADIO PULSAR PSR B1509–58

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ge; Kaspi, Victoria M. [Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada); An, Hongjun [Department of Physics/KIPAC, Stanford University, Stanford, CA 94305-4060 (United States); Harrison, Fiona A.; Madsen, Kristin K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-221, Pasadena, CA 91109 (United States)

    2016-02-01

    We report on Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of the young rotation-powered radio pulsar PSR B1509−59 in the supernova remnant MSH 15−52. We confirm the previously reported curvature in the hard X-ray spectrum, showing that a log parabolic model provides a statistically superior fit to the spectrum compared with the standard power law. The log parabolic model describes the NuSTAR data, as well as previously published γ-ray data obtained with COMPTEL and AGILE, all together spanning 3 keV through 500 MeV. Our spectral modeling allows us to constrain the peak of the broadband high energy spectrum to be at 2.6 ± 0.8 MeV, an improvement of nearly an order of magnitude in precision over previous measurements. In addition, we calculate NuSTAR spectra in 26 pulse phase bins and confirm previously reported variations of photon indices with phase. Finally, we measure the pulsed fraction of PSR B1509−58 in the hard X-ray energy band for the first time. Using the energy resolved pulsed fraction results, we estimate that the pulsar’s off-pulse emission has a photon index value between 1.26 and 1.96. Our results support a model in which the pulsar’s lack of GeV emission is due to viewing geometry, with the X-rays originating from synchrotron emission from secondary pairs in the magnetosphere.

  18. PSR J1907+0602: A Radio-Faint Gamma-Ray Pulsar Powering a Bright TeV Pulsar Wind Nebula

    CERN Document Server

    Abdo, A A

    2010-01-01

    We present multiwavelength studies of the 106.6 ms gamma-ray pulsar PSR J1907+06 near the TeV source MGRO J1908+06. Timing observations with Fermi result in a precise position determination for the pulsar of R.A. = 19h07m547(2), decl. = +06:02:16(2) placing the pulsar firmly within the TeV source extent, suggesting the TeV source is the pulsar wind nebula of PSR J1907+0602. Pulsed gamma-ray emission is clearly visible at energies from 100 MeV to above 10 GeV. The phase-averaged power-law index in the energy range E > 0.1 GeV is = 1.76 \\pm 0.05 with an exponential cutoff energy E_{c} = 3.6 \\pm 0.5 GeV. We present the energy-dependent gamma-ray pulsed light curve as well as limits on off-pulse emission associated with the TeV source. We also report the detection of very faint (flux density of ~3.4 microJy) radio pulsations with the Arecibo telescope at 1.5 GHz having a dispersion measure DM = 82.1 \\pm 1.1 cm^{-3}pc. This indicates a distance of 3.2 \\pm 0.6 kpc and a pseudo-luminosity of L_{1400} ~ 0.035 mJy kpc...

  19. Evidence of residual Doppler shift on three pulsars, PSR B1259-63, 4U1627-67 and PSR J2051-0827

    CERN Document Server

    Gong, Biping

    2014-01-01

    The huge derivative of orbital period observed in binary pulsar PSR B1259-63, the torque reversal displaying on low mass X-ray binary, 4U1627-67 and the long term change of orbital period of PSR J2051-0827, seem totally unrelated phenomena occurring at totally different pulsar systems. In this paper, they are simply interpreted by the same mechanism, residual Doppler shift. In a binary system with periodic signals sending to an observer, the drift of the signal frequency actually changes with the varying orbital velocity, projected to line of sight at different phases of orbit. And it has been taken for granted that the net red-shift and blue-shift of an full orbit circle be cancelled out, so that the effect of Doppler shift to the signal in binary motion cannot be accumulated over the orbital period. However, taking the propagation time at each velocity state into account, the symmetry of the velocity distribution over the orbital phase is broken. Consequently, the net Doppler shift left in an orbit is non-z...

  20. Magnetar-like Activity and Radio Emission Variability from the High Magnetic Field Pulsar PSR J1119-6127

    Science.gov (United States)

    Pearlman, Aaron B.; Majid, Walid A.; Horiuchi, Shinji; Kocz, Jonathon; Lippuner, Jonas; Prince, Thomas Allen

    2017-08-01

    We present results from a high frequency radio monitoring campaign of the high magnetic field pulsar PSR J1119-6127 with the Deep Space Network (DSN) 70 m antenna (DSS-43) in Canberra, Australia, following recently reported magnetar-like activity. Dramatic pulsed radio emission variability was observed over several months at S-band (2.3 GHz) and X-band (8.4 GHz) after an initial disappearance of radio pulsations. The S-band pulse profile evolved from a multiple-peaked structure into a single-peak over several weeks, which is extremely unusual for radio pulsars. We also observed significant differences between the polarized pulse profiles at both S-band and X-band. In addition, pulsed emission variability was observed on shorter timescales, of order tens of minutes, during individual observations.The spectral index from 2.3 GHz to 8.4 GHz varied between flux densities exceeding 0.49/0.27 Jy.Although PSR J1119-6127 is normally a rotation-powered pulsar, it is possible that the decay of the pulsar’s strong magnetic field, together with other magnetar-like mechanisms, may be responsible for the observed emission variability. We will discuss how these results could connect magnetars with high-B field pulsars.

  1. The binary millisecond pulsar PSR J1023+0038 during its accretion state - I. Optical variability

    Science.gov (United States)

    Shahbaz, T.; Linares, M.; Nevado, S. P.; Rodríguez-Gil, P.; Casares, J.; Dhillon, V. S.; Marsh, T. R.; Littlefair, S.; Leckngam, A.; Poshyachinda, S.

    2015-11-01

    We present time-resolved optical photometry of the binary millisecond `redback' pulsar PSR J1023+0038 (=AY Sex) during its low-mass X-ray binary phase. The light curves taken between 2014 January and April show an underlying sinusoidal modulation due to the irradiated secondary star and accretion disc. We also observe superimposed rapid flaring on time-scales as short as ˜20 s with amplitudes of ˜0.1-0.5 mag and additional large flare events on time-scales of ˜5-60 min with amplitudes of ˜0.5-1.0 mag. The power density spectrum of the optical flare light curves is dominated by a red-noise component, typical of aperiodic activity in X-ray binaries. Simultaneous X-ray and UV observations by the Swift satellite reveal strong correlations that are consistent with X-ray reprocessing of the UV light, most likely in the outer regions of the accretion disc. On some nights we also observe sharp-edged, rectangular, flat-bottomed dips randomly distributed in orbital phase, with a median duration of ˜250 s and a median ingress/egress time of ˜20 s. These rectangular dips are similar to the mode-switching behaviour between disc `active' and `passive' luminosity states, observed in the X-ray light curves of other redback millisecond pulsars. This is the first time that the optical analogue of the X-ray mode-switching has been observed. The properties of the passive- and active-state light curves can be explained in terms of clumpy accretion from a trapped inner accretion disc near the corotation radius, resulting in rectangular, flat-bottomed optical and X-ray light curves.

  2. Revealing the X-ray emission processes of old rotation-powered pulsars: XMM-Newton Observations of PSR B0950+08,PSR B0823+26 and PSR J2043+2740

    CERN Document Server

    Becker, W; Tennant, A F; Jessner, A; Dyks, J; Harding, A K; Zhang, S N; Becker, Werner; Weisskopf, Martin C.; Tennant, Allyn F.; Jessner, Axel; Dyks, Jaroslaw; Harding, Alice K.; Zhang, Shuang N.

    2004-01-01

    We have completed part of a program to study the X-ray emission properties of old rotation-powered pulsars with XMM-Newton in order to probe and identify the origin of their X-radiation. The X-ray emission from these old pulsars is largely dominated by non-thermal processes. None of the observed spectra required adding a thermal component consisting of either a hot polar cap or surface cooling emission to model the data. The X-ray spectrum of PSR 0950+08 is best described by a single power law of photon-index 1.93^{+0.14}_{-0.12}.Taking optical data from the VLT FORS1 into account a broken power law model is found to describe the pulsar's broadband spectrum from the optical to the X-ray band. Temperature upper limits for possible contributions from a heated polar cap or the whole neutron star surface are T_{pc} < 0.87 x10^6 K and T_s < 0.48 x 10^6 K, respectively. We also find that the X-ray emission from PSR 0950+08 is pulsed with two peaks per rotation period. The phase separation between the two X-ra...

  3. Testing the rotating lighthouse model with the double pulsar system PSR J0737-3039A/B

    Science.gov (United States)

    Liang, Zhu-Xing; Liang, Yi; Weisberg, Joel M.

    2014-04-01

    Each of the two pulsars in the double pulsar PSR J0737-3039A/B system exhibits not only the pulses emanating from it, but also displays modulations near the pulse period of the other. Freire et al. (2009, MNRAS, 396, 1764) have put forward a technique using the modulation of B by A to determine the sense of rotation of pulsar A relative to its orbital motion, among other quantities. In this paper, we present another technique with the same purpose. While the Freire et al. approach analyses pulse arrival times, ours instead uses periods or frequencies (their inverses), which can be experimentally determined via power spectral analysis similar to that used in pulsar searches. Our technique is based on the apparent change in spin period of a body when it is measured from an orbiting platform (the other pulsar), and is shown to be entirely analogous to the difference between the sidereal and solar spin period of the Earth (i.e. the sidereal and solar day). Two benefits of this approach are its conceptual and computational simplicity. The direct detection of spin with this technique will observationally validate the rotating lighthouse model of pulsar emission, while the detection of the relative directions of spin and orbital angular momenta has important evolutionary implications. Our technique can be used on other binary systems exhibiting mutually induced phenomena.

  4. The binary millisecond pulsar PSR J1023+0038 during its accretion state - I. Optical variability

    CERN Document Server

    Shahbaz, T; Nevado, S P; Rodríguez-Gil, P; Casares, J; Dhillon, V S; Marsh, T R; Littlefair, S; Leckngam, A; Poshyachinda, S

    2015-01-01

    We present time-resolved optical photometry of the binary millisecond `redback' pulsar PSR J1023+0038 (=AY Sex) during its low-mass X-ray binary phase. The light curves taken between 2014 January and April show an underlying sinusoidal modulation due to the irradiated secondary star and accretion disc. We also observe superimposed rapid flaring on time-scales as short as ~20 s with amplitudes of ~0.1-0.5 mag and additional large flare events on time-scales of ~5-60 min with amplitudes ~0.5-1.0 mag. The power density spectrum of the optical flare light curves is dominated by a red-noise component, typical of aperiodic activity in X-ray binaries. Simultaneous X-ray and UV observations by the Swift satellite reveal strong correlations that are consistent with X-ray reprocessing of the UV light, most likely in the outer regions of the accretion disc. On some nights we also observe sharp-edged, rectangular, flat-bottomed dips randomly distributed in orbital phase, with a median duration of ~250 s and a median ingr...

  5. Testing the strong equivalence principle with the triple pulsar PSR J 0337 +1715

    Science.gov (United States)

    Shao, Lijing

    2016-04-01

    Three conceptually different masses appear in equations of motion for objects under gravity, namely, the inertial mass, mI , the passive gravitational mass, mP, and the active gravitational mass, mA. It is assumed that, for any objects, mI=mP=mA in the Newtonian gravity, and mI=mP in the Einsteinian gravity, oblivious to objects' sophisticated internal structure. Empirical examination of the equivalence probes deep into gravity theories. We study the possibility of carrying out new tests based on pulsar timing of the stellar triple system, PSR J 0337 +1715 . Various machine-precision three-body simulations are performed, from which, the equivalence-violating parameters are extracted with Markov chain Monte Carlo sampling that takes full correlations into account. We show that the difference in masses could be probed to 3 ×1 0-8 , improving the current constraints from lunar laser ranging on the post-Newtonian parameters that govern violations of mP=mI and mA=mP by thousands and millions, respectively. The test of mP=mA would represent the first test of Newton's third law with compact objects.

  6. PSR J2021+3651 A Young Radio Pulsar Coincident with an Unidentified EGRET Gamma-ray Source

    CERN Document Server

    Roberts, M S E; Ransom, S M; Kaspi, V M; Freire, P C C; Crawford, F; Lorimer, D R; Roberts, Mallory S.E.; Hessels, Jason W.T.; Ransom, Scott M.; Kaspi, Victoria M.; Freire, Paulo C.C.; Crawford, Fronefield; Lorimer, Duncan R.

    2002-01-01

    We report on a deep search for radio pulsations toward five unidentified ASCA X-ray sources coincident with EGRET gamma-ray sources. This search has led to the discovery of a young and energetic pulsar using data obtained with the new Wideband Arecibo Pulsar Processor. PSR J2021+3651 is likely associated with the X-ray source AX J2021.1+3651, which in turn is likely associated with the COS B high energy gamma-ray source 2CG 075+00, also known as GeV J2020+3658 or 3EG J2021+3716. PSR J2021+3651 has a rotation period P = 104 ms and P_dot = 9.6x10^{-14}, implying a characteristic age ~17 kyr and a spin-down luminosity E_dot ~ 3.4x10^{36}ergs/s. The dispersion measure DM ~ 371 pc cm^{-3} is by far the highest of any observed pulsar in the Galactic longitude range 55 10 kpc, and a high gamma-ray efficiency of \\~15%, but the true distance may be closer if there is a significant contribution to the DM from excess gas in the Cygnus region. The implied luminosity of the associated X-ray source suggests the X-ray emis...

  7. The young pulsar PSR B0540-69.3 and its synchrotron nebula in the optical and X-rays

    CERN Document Server

    Serafimovich, N I; Lundqvist, P; Sollerman, J; Shibanov, Yu. A.

    2004-01-01

    The young PSR B0540-69 (B0540) in the LMC is the only pulsar (except the Crab pulsar) for which a near-UV spectrum has been obtained. However, the absolute flux and spectral index of previously published HST/FOS data are significantly higher than suggested by broadband groundbased UBVRI photometry. Using our ESO/VLT/FORS1 spectral observations and HST/WFPC2 archival images we show that the old HST and new VLT spectral data are >50% contaminated by the Pulsar Wind Nebula (PWN) and that this is the reason for the above mentioned difference. We find that the broadband HST spectrum for the range 3300-8000 A is clearly non- thermal and has a negative spectral index of 1.07(+0.20/-0.19). This is dif- ferent from the almost flat spectrum of the Crab pulsar. The PWN of B0540 shows a clear asymmetry of the surface brightness distribution along the major axis of the PWN torus-like structure with respect to the pulsar position, also seen in Chandra X-ray images. This can be linked to the asymmetry of the surrounding SN ...

  8. X-Ray Analysis of the Proper Motion and Pulsar Wind Nebula for PSR J1741-2054

    Science.gov (United States)

    Auchettl, Katie; Slane, Patrick; Romani, Roger W.; Posselt, Bettina; Pavlov, George G.; Kargaltsev, Oleg; Ng, C-Y.; Temim, Tea; Weisskopf, Martin C.; Bykov, Andrei; hide

    2015-01-01

    We obtained six observations of PSR J1741-2054 using the Chandra ACIS-S detector totaling approx.300 ks. By registering this new epoch of observations to an archival observation taken 3.2 yr earlier using X-ray point sources in the field of view, we have measured the pulsar proper motion at micron = 109 +/- 10 mas yr(exp. -1) in a direction consistent with the symmetry axis of the observed H(alpha) nebula. We investigated the inferred past trajectory of the pulsar but find no compelling association with OB associations in which the progenitor may have originated. We confirm previous measurements of the pulsar spectrum as an absorbed power law with photon index gamma = 2.68 +/- 0.04, plus a blackbody with an emission radius of (4.5(+3.2/-2.5))d(0.38) km, for a DM-estimated distance of 0.38d(0.38) kpc and a temperature of 61.7 +/- 3.0 eV. Emission from the compact nebula is well described by an absorbed power law model with a photon index of gamma = 1.67 +/- 0.06, while the diffuse emission seen as a trail extending northeast of the pulsar shows no evidence of synchrotron cooling. We also applied image deconvolution techniques to search for small-scale structures in the immediate vicinity of the pulsar, but found no conclusive evidence for such structures.

  9. GMRT discovery of PSR J1544+4937, an eclipsing black-widow pulsar identified with a Fermi LAT source

    CERN Document Server

    Bhattacharyya, B; Ray, P S; Gupta, Y; Bhattacharya, D; Romani, R W; Ransom, S M; Ferrara, E C; Wolff, M T; Camilo, F; Cognard, I; Harding, A K; Hartog, P R den; Johnston, S; Keith, M; Kerr, M; Michelson, P F; Parkinson, P M Saz; Wood, D L; Wood, K S

    2013-01-01

    Using the Giant Metrewave Radio Telescope (GMRT) we performed deep observations to search for radio pulsations in the directions of unidentified Fermi Large Area Telescope (LAT) gamma-ray sources. We report the discovery of an eclipsing black-widow millisecond pulsar, PSR J1544+4937, identified with the un-cataloged gamma-ray source Fermi J1544.2+4941. This 2.16 ms pulsar is in a 2.9 hours compact circular orbit with a very low-mass companion (Mc > 0.017 Msun). At 322 MHz this pulsar is found to be eclipsing for 13% of its orbit, whereas at 607 MHz the pulsar is detected throughout the low-frequency eclipse phase. Variations in the eclipse ingress phase are observed, indicating a clumpy and variable eclipsing medium. Moreover, additional short-duration absorption events are observed around the eclipse boundaries. Using the radio timing ephemeris we were able to detect gamma-ray pulsations from this pulsar, confirming it as the source powering the gamma-ray emission.

  10. X-Ray Analysis of the Proper Motion and Pulsar Wind Nebula for PSR J1741-2054

    Science.gov (United States)

    Auchettl, Katie; Slane, Patrick; Romani, Roger W.; Posselt, Bettina; Pavlov, George G.; Kargaltsev, Oleg; Ng, C-Y.; Temim, Tea; Weisskopf, Martin C.; Bykov, Andrei; Swartz, Douglas

    2015-01-01

    We obtained six observations of PSR J1741-2054 using the Chandra ACIS-S detector totaling approx.300 ks. By registering this new epoch of observations to an archival observation taken 3.2 yr earlier using X-ray point sources in the field of view, we have measured the pulsar proper motion at micron = 109 +/- 10 mas yr(exp. -1) in a direction consistent with the symmetry axis of the observed H(alpha) nebula. We investigated the inferred past trajectory of the pulsar but find no compelling association with OB associations in which the progenitor may have originated. We confirm previous measurements of the pulsar spectrum as an absorbed power law with photon index gamma = 2.68 +/- 0.04, plus a blackbody with an emission radius of (4.5(+3.2/-2.5))d(0.38) km, for a DM-estimated distance of 0.38d(0.38) kpc and a temperature of 61.7 +/- 3.0 eV. Emission from the compact nebula is well described by an absorbed power law model with a photon index of gamma = 1.67 +/- 0.06, while the diffuse emission seen as a trail extending northeast of the pulsar shows no evidence of synchrotron cooling. We also applied image deconvolution techniques to search for small-scale structures in the immediate vicinity of the pulsar, but found no conclusive evidence for such structures.

  11. Testing the rotating lighthouse model with the double pulsar system PSR J0737-3039A/B

    CERN Document Server

    Liang, Zhu-Xing; Weisberg, Joel M

    2014-01-01

    Each of the two pulsars in the double pulsar PSR J0737-3039A/B system exhibits not only the pulses emanating from itself, but also displays modulations near the pulse period of the other. Freire et al. (2009, MNRAS, 396, 1764) have put forward a technique using the modulation of B by A to determine the sense of rotation of pulsar A relative to its orbital motion, among other quantities. In this paper, we present another technique with the same purpose. While the Freire et al. approach analyzes pulse arrival times, ours instead uses periods or frequencies (their inverses), which can be experimentally determined via power spectral analysis similar to that used in pulsar searches. Our technique is based on the apparent change in spin period of a body when it is measured from an orbiting platform (the other pulsar), and is shown to be entirely analogous to the difference between the sidereal and solar spin period of the Earth (i.e., the sidereal and solar day). Two benefits of this approach are its conceptual and...

  12. Probing the Pulsar Wind in the gamma-ray Binary System PSR B1259-63/SS 2883

    CERN Document Server

    Takata, Jumpei

    2009-01-01

    The spectral energy distribution from the X-ray to the very high energy regime ($>100$ GeV) has been investigated for the $\\gamma$-ray binary system PSR B1259-63/SS2883 as a function of orbital phase within the framework of a simple model of a pulsar wind nebula. The emission model is based on the synchrotron radiation process for the X-ray regime and the inverse Compton scattering process boosting stellar photons from the Be star companion to the very high energy (100GeV-TeV) regime. With this model, the observed temporal behavior can, in principle, be used to probe the pulsar wind properties at the shock as a function of the orbital phase. Due to theoretical uncertainties in the detailed microphysics of the acceleration process and the conversion of magnetic energy into particle kinetic energy, the observed X-ray data for the entire orbit are fit using two different methods.

  13. On the Formation and Progenitor of PSR J0737-3039: New Constraints on the Supernova Explosion Forming Pulsar B

    CERN Document Server

    Willems, B; Fragos, T; Kalogera, V; Kaplan, J

    2006-01-01

    We revisit the formation of PSR J0737-3039, taking into account the most recent observational constraints. We show that the most likely kick velocity and progenitor parameters depend strongly on the consideration of the full five-dimensional PDF for the magnitude and direction of the kick velocity imparted to pulsar B at birth, the mass of pulsar B's pre-supernova helium star progenitor, and the pre-supernova orbital separation, and on the adopted prior assumptions. The priors consist of the transverse systemic velocity, the age of the system, and the treatment of the unknown radial velocity. Since the latter cannot be determined from observation, we adopt a statistical approach and use theoretical radial-velocity distributions obtained from population synthesis calculations for coalescing double neutron stars. We find that the prior assumptions about the pre-supernova helium star mass affect the derived most likely parameters significantly: when the minimum helium star mass required for neutron star formatio...

  14. A pilot ASKAP survey of radio transient events in the region around the intermittent pulsar PSR J1107-5907

    CERN Document Server

    Hobbs, G; Bell, M E; Kerr, M; Rowlinson, A; Johnston, S; Shannon, R M; Voronkov, M A; Ward, C; Banyer, J; Hancock, P J; Murphy, Tara; Allison, J R; Amy, S W; Ball, L; Bannister, K; Bock, D C -J; Brodrick, D; Brothers, M; Brown, A J; Bunton, J D; Chapman, J; Chippendale, A P; Chung, Y; DeBoer, D; Diamond, P; Edwards, P G; Ekers, R; Ferris, R H; Forsyth, R; Gough, R; Grancea, A; Gupta, N; Harvey-Smith, L; Hay, S; Hayman, D B; Hotan, A W; Hoyle, S; Humphreys, B; Indermuehle, B; Jacka, C E; Jackson, C A; Jackson, S; Jeganathan, K; Joseph, J; Kendall, R; Kiraly, D; Koribalski, B; Leach, M; Lenc, E; MacLeod, A; Mader, S; Marquarding, M; Marvil, J; McClure-Griffiths, N; McConnell, D; Mirtschin, P; Neuhold, S; Ng, A; Norris, R P; O'Sullivan, J; Pearce, S; Phillips, C J; Popping, A; Qiao, R Y; Reynolds, J E; Roberts, P; Sault, R J; Schinckel, A E T; Serra, P; Shaw, R; Shimwell, T W; Storey, M; Sweetnam, A W; Tzioumis, A; Westmeier, T; Whiting, M; Wilson, C D

    2015-01-01

    We use observations from the Boolardy Engineering Test Array (BETA) of the Australian Square Kilometre Array Pathfinder (ASKAP) telescope to search for transient radio sources in the field around the intermittent pulsar PSR J1107-5907. The pulsar is thought to switch between an "off" state in which no emission is detectable, a weak state and a strong state. We ran three independent transient detection pipelines on two-minute snapshot images from a 13 hour BETA observation in order to 1) study the emission from the pulsar, 2) search for other transient emission from elsewhere in the image and 3) to compare the results from the different transient detection pipelines. The pulsar was easily detected as a transient source and, over the course of the observations, it switched into the strong state three times giving a typical timescale between the strong emission states of 3.7 hours. After the first switch it remained in the strong state for almost 40 minutes. The other strong states lasted less than 4 minutes. Th...

  15. A Shapiro delay detection in the binary system hosting the millisecond pulsar PSR J1910-5959A

    CERN Document Server

    Corongiu, A; Possenti, A; Camilo, F; D'Amico, N; Lyne, A G; Manchester, R N; Sarkissian, J M; Bailes, M; Johnston, S; Kramer, M; van Straten, W

    2012-01-01

    PSR J1910-5959A is a binary pulsar with a helium white dwarf companion located about 6 arcmin from the center of the globular cluster NGC6752. Based on 12 years of observations at the Parkes radio telescope, the relativistic Shapiro delay has been detected in this system. We obtain a companion mass Mc = 0.180+/-0.018Msun (1sigma) implying that the pulsar mass lies in the range 1.1Msun <= Mp <= 1.5Msun. We compare our results with previous optical determinations of the companion mass, and examine prospects for using this new measurement for calibrating the mass-radius relation for helium white dwarfs and for investigating their evolution in a pulsar binary system. Finally we examine the set of binary systems hosting a millisecond pulsar and a low mass helium white dwarf for which the mass of both stars has been measured. We confirm that the correlation between the companion mass and the orbital period predicted by Tauris & Savonije reproduces the observed values but find that the predicted Mp - Pb co...

  16. Rossi X-Ray Timing Explorer Observation of PSR B1706-44 and Implications for Theoretical Models of Pulsar Emission

    CERN Document Server

    Ray, A K; Strickman, M S

    1999-01-01

    We report on results of an observation with the Rossi X-Ray Timing Explorer (RXTE) of PSR B1706-44 with a live time of 132 ks, to search for pulsed X-ray emission. PSR B1706-44 is a radio and high-energy gamma-ray pulsar (detected by EGRET), but no pulsed emission has been detected in the X-ray band. Since most of the other known gamma-ray pulsars emit pulsed X-rays, it is expected that PSR B1706-44 would also be an X-ray pulsar. However, while the ROSAT PSPC detected a source at the pulsar position, it did not detect pulsations, giving a pulsed fraction upper limit of 18%. The RXTE observations to search for modulation at the pulsar period were carried out in November 1996 and May 1997, during the low states of the nearby X-ray binary 4U1705-44. No significant modulation was detected at the pulsar period, giving an upper limit of 10^{-6} photons cm^{-2} s^{-1} keV^{-1} in the interval 9 keV < E < 18.5keV. The implications of this upper limit of the pulsed flux from the RXTE observation, taken together ...

  17. The relativistic pulsar-white dwarf binary PSR J1738+0333 I. Mass determination and evolutionary history

    CERN Document Server

    Antoniadis, J; Koester, D; Freire, P C C; Wex, N; Tauris, T M; Kramer, M; Bassa, C G

    2012-01-01

    PSR J1738+0333 is one of the four millisecond pulsars known to be orbited by a white dwarf companion bright enough for optical spectroscopy. Of these, it has the shortest orbital period, making it especially interesting for a range of astrophysical and gravity related questions. We present a spectroscopic and photometric study of the white dwarf companion and infer its radial velocity curve, effective temperature, surface gravity and luminosity. We find that the white dwarf has properties consistent with those of low-mass white dwarfs with thick hydrogen envelopes, and use the corresponding mass-radius relation to infer its mass; M_WD = 0.181 +/- +0.007/-0.005 solar masses. Combined with the mass ratio q=8.1 +/- 0.2 inferred from the radial velocities and the precise pulsar timing ephemeris, the neutron star mass is constrained to M_PSR = 1.47 +/- +0.07/-0.06 solar masses. Contrary to expectations, the latter is only slightly above the Chandrasekhar limit. We find that, even if the birth mass of the neutron s...

  18. A Multi-wavelength study of the Pulsar PSR B1929+10 and its X-ray trail

    CERN Document Server

    Becker, W; Jessner, A; Taam, R E; Jia, J J; Cheng, K S; Mignani, R; Pellizzoni, A; De Luca, A; Slowikowska, A; Caraveo, P A; Becker, Werner; Kramer, Michael; Jessner, Axel; Taam, Ronald E.; Jia, Jian J.; Cheng, Kwong S.; Mignani, Roberto; Pellizzoni, Alberto; Luca, Andrea de; Slowikowska, Agnieszka; Caraveo, Patrizia

    2005-01-01

    We report on the emission properties of PSR B1929+10 and its putative X-ray trail from a multi-wavelength study performed with XMM-Newton, the ESO NTT, the HST, the Effelsberg 100m Radio Telescope and the Jodrell Bank Radio Observatory. The XMM-Newton observations confirm the existence of the diffuse emission with a trail morphology lying in a direction opposite to the transverse motion of the pulsar. The trail has a length of ~15 arcmin. Its spectrum is non-thermal and produced by electron-synchrotron emission in the shock between the pulsar wind and the surrounding medium. Assuming that the electron lifetime against synchrotron cooling is comparable to the source transit time over the X-ray trail length, the magnetic field strength in the trail emitting region is inferred to be ~5 uG. Inspecting data from the Effelsberg 11cm radio continuum survey of the Galactic plane we discovered an elongated feature apparently coincident with the X-ray trail. The emission properties observed from PSR 1929+10 are found t...

  19. Multi-wavelength emissions from the millisecond pulsar binary PSR J1023+0038 during an accretion active state

    CERN Document Server

    Takata, J; Leung, G C K; Kong, A K H; Tam, P H T; Hui, C Y; Wu, E M H; Xing, Y; Cao, Y; Tang, S; Wang, Z; Cheng, K S

    2013-01-01

    Recent observations strongly suggest that the millisecond pulsar binary PSR J1023+0038 has developed an accretion disk since 2013 June. We present the multi-wavelength analysis of PSR J1023+0038, which reveals that 1) its gamma-rays suddenly brightened within a few days in June/July 2013 and has remained at a high gamma-ray state for several months; 2) both UV and X-ray fluxes have increased by roughly an order of magnitude, and 3) the spectral energy distribution has changed significantly after the gamma-ray sudden flux change. Time variabilities associated with UV and X-rays are on the order of 100-500 seconds and 50-100 seconds respectively. Our model suggests that a newly formed accretion disk due to the sudden increase of the stellar wind could explain the changes of all these observed features. The increase of UV is emitted from the disk, and a new component in gamma-rays is produced by inverse Compton scattering between the new UV component and pulsar wind. The increase of X-rays results from the enhan...

  20. Historical Evidence for the Birth of the Newly Discovered Pulsar PSR J1833-1034

    Institute of Scientific and Technical Information of China (English)

    Zhen-Ru Wang; Min Li; Yi Zhao

    2006-01-01

    Stimulated by the recent discovery of PSR J 1833-1034 in SNR G21.5-0.9 and its age parameters presented by two groups of discovery, we demonstrate that the PSR J1833- 1034 was born 2053 years ago from a supernova explosion, the BC 48 guest star observed in the Western Han (Early Han) Dynasty by ancient Chinese. Based on a detailed analysis of the Chinese ancient record of the BC 48 guest star and the new detected physical parameters of PSR J1833-1034, agreements on the visual position, age and distance between PSR J1833- 1034 and the BC 48 guest star are obtained. The initial period P0 of PSR J 1833-1034 is now derived from its historical and current observed data without any other extra assumption on P0 itself, except that the factor PP is a constant in its evolution until now.s

  1. Theory of High-Energy Emission from the Pulsar/Be Star System PSR 1259-63. I. Radiation Mechanisms and Interaction Geometry

    Science.gov (United States)

    Tavani, Marco; Arons, Jonathan

    1997-03-01

    We study the physical processes in the system containing the 47 ms radio pulsar PSR B1259-63 orbiting around a Be star in a highly eccentric orbit. This system is the only known binary where a radio pulsar is observed to interact with gaseous material from a Be star. A rapidly rotating radio pulsar such as PSR B1259-63 is expected to produce a wind of electromagnetic emission and relativistic particles, and this binary is an ideal astrophysical laboratory to study the mass outflow/pulsar interaction in a highly time-variable environment. Motivated by the results of a recent multiwavelength campaign during the 1994 January periastron passage of PSR B1259-63, we discuss several issues regarding the mechanism of high-energy emission. Unpulsed power-law emission from the PSR B1259-63 system was detected near periastron in the energy range 1-200 keV. The observed X-ray/soft γ-ray emission is characterized by moderate luminosity, small and constant column density, lack of detectable pulsations, and peculiar spectral and intensity variability. In principle, high-energy (X-ray and gamma-ray) emission from the system can be produced by different mechanisms including (1) mass accretion onto the surface of the neutron star, (2) ``propeller''-like magnetospheric interaction at a small pulsar distance, and (3) shock-powered emission in a pulsar wind termination shock at a large distance from the pulsar. We carry out a series of calculations aimed at modeling the high-energy data of the PSR B1259-63 system throughout its orbit and especially near periastron. We find that the observed high-energy emission from the PSR B1259-63 system is not compatible with accretion or propeller-powered emission. This conclusion is supported by a model based on standard properties of Be stars and for plausible assumptions about the pulsar/outflow interaction geometry. We find that shock-powered high-energy emission produced by the pulsar/outflow interaction is consistent with all the

  2. The Nearest Millisecond Pulsar Revisited with XMM-Newton: Improved Mass-Radius Constraints for PSR J0437-4715

    CERN Document Server

    Bogdanov, Slavko

    2012-01-01

    I present an analysis of the deepest X-ray exposure of a radio millisecond pulsar (MSP) to date, an X-ray Multi Mirror-Newton European Photon Imaging Camera spectroscopic and timing observation of the nearest known MSP, PSR J0437--4715. The timing data clearly reveal a secondary broad X-ray pulse offset from the main pulse by $\\sim$0.55 in rotational phase. In the context of a model of surface thermal emission from the hot polar caps of the neutron star, this can be plausibly explained by a magnetic dipole field that is significantly displaced from the stellar center. Such an offset, if commonplace in MSPs, has important implications for studies of the pulsar population, high energy pulsed emission, and the pulsar contribution to cosmic ray positrons. The continuum emission shows evidence for at least three thermal components, with the hottest radiation most likely originating from the hot magnetic polar caps and the cooler emission from the bulk of the surface. I present pulse phase-resolved X-ray spectrosco...

  3. Timing, polarimetry and physics of the bright, nearby millisecond pulsar PSR J0437-4715 - a single-pulse perspective

    CERN Document Server

    Osłowski, S; Bailes, M; Jameson, A; Hobbs, G

    2014-01-01

    Single pulses from radio pulsars contain a wealth of information about emission and propagation in the magnetosphere and insight into their timing properties. It was recently demonstrated that single-pulse emission is responsible for limiting the timing stability of the brightest of millisecond pulsars. We report on an analysis of more than a million single-pulses from PSR J0437-4715 and present various statistical properties such as the signal-to-noise ratio (S/N) distribution, timing and polarimetry of average profiles integrated from subpulses with chosen S/N cut-offs, modulation properties of the emission, phase-resolved statistics of the S/N, and two dimensional spherical histograms of the polarization vector orientation. The last of these indicates the presence of orthogonally polarised modes (OPMs). Combined with the dependence of the polarisation fraction on the S/N and polarimetry of the brightest pulses, the existence of OPMs constrains pulsar emission mechanisms and models for the plasma physics in...

  4. X-ray analysis of the proper motion and pulsar wind nebula for PSR J1741-2054

    CERN Document Server

    Auchettl, Katie; Romani, Roger W; Posselt, Bettina; Pavlov, George G; Kargaltsev, Oleg; Ng, C-Y; Temim, Tea; Weisskopf, Martin C; Bykov, Andrei; Swartz, Douglas A

    2015-01-01

    We obtained six observations of PSR J1741-2054 using the $Chandra$ ACIS-S detector totaling $\\sim$300 ks. By registering this new epoch of observations to an archival observation taken 3.2 years earlier using X-ray point sources in the field of view, we have measured the pulsar proper motion at $\\mu =109 \\pm 10$ mas/yr. The spectrum of the pulsar can be described by an absorbed power law with photon index $\\Gamma$=2.68$\\pm$0.04, plus a blackbody with an emission radius of (4.5$^{+3.2}_{-2.5})d_{0.38}$ km, for a DM-estimated distance of $0.38d_{0.38}$ kpc and a temperature of $61.7\\pm3.0$ eV. Emission from the compact nebula is well described by an absorbed power law model with a photon index of $\\Gamma$ = 1.67$\\pm$0.06, while the diffuse emission seen as a trail extending northeast of the pulsar shows no evidence of synchrotron cooling. We also looked for extended features that might represent a jet or torus-like structure using image deconvolution and PSF-subtraction but we find no conclusive evidence of suc...

  5. Chandra observations of the pulsar PSR B1929+10 and its environment

    CERN Document Server

    Misanovic, Zdenka; Garmire, Gordon

    2007-01-01

    We report on two Chandra observations of the 3-Myr pulsar B1929+10, which reveal a faint compact (~9"x4") nebula elongated in the direction perpendicular to the pulsar's proper motion, two patchy wings, and a possible short (~3") jet emerging from the pulsar. In addition, we detect a tail extending up to at least 4' in the direction opposite to the pulsar's proper motion, aligned with the 15'-long tail detected in ROSAT and XMM-Newton observations. The overall morphology of the nebula suggests that the shocked pulsar wind is confined by the ram pressure due to the pulsar's supersonic speed. The shape of the compact nebula in the immediate vicinity of the pulsar seems to be consistent with the current MHD models. However, since these models do not account yet for the change of the flow velocity at larger distances from the pulsar, they are not able to constrain the extent of the long pulsar tail. The luminosity of the whole nebula as seen by Chandra is ~10^30 ergs/s in the 0.3-8 keV band, for the distance of 3...

  6. Magnetar-like Spectral Index Flattening of the High Magnetic Field Pulsar PSR J1119-6127

    Science.gov (United States)

    Pearlman, Aaron B.; Majid, Walid A.; Horiuchi, Shinji; Kocz, Jonathon; Lippuner, Jonas; Prince, Thomas A.

    2016-12-01

    Dramatic changes in pulsed radio emission have been reported by Majid et al. (2016; arXiv:1612.02868) from the high magnetic field pulsar PSR J1119-6127 at S-band (2.3 GHz) and X-band (8.4 GHz) following the reactivation of its radio emission (Burgay et al., ATel #9366). Magnetar-like outbursts have also been observed in X-rays and gamma-rays (Kennea et al., GCN Circular #19735; Younes et al., GCN Circular #19736; Kenna et al., ATel #9274; Archibald et al. (2016); Göǧüş, et al. (2016)). We report our observations of PSR J1119-6127, spanning 1.7 hours on 03 December 2016 starting at UT 15:36:52, using the 70-m diameter Deep Space Network (DSN) radio dish (DSS-43) in Canberra, Australia. The data were recorded in filterbank search mode using 512 us time resolution. The receivers and data acquisition system are described in detail in Majid et al. (2016; arXiv:1612.02868). Pulsations were detected at S-band (2.3 GHz, 96 MHz bandwidth) and X-band (8.4 GHz, 480 MHz bandwidth) in dual circular polarization mode at a period of 0.40996974(6) s using the PRESTO pulsar search package (http://www.cv.nrao.edu/~sransom/presto). Both polarizations were combined in quadrature, and pulsed emission was seen at S/X-band with a peak signal-to-noise ratio (SNR) of 17.2/54.5. The pulse profile at S-band appears roughly singly peaked, with a smaller secondary peak near the dominant emission component. At X-band, the pulse profile shows a strong, narrow single peak. We measure a mean flux density of 0.18(4)/0.08(2) mJy at S/X-band, which represents an order of magnitude decrease at S-band and roughly a factor of 2 decrease at X-band compared to previous measurements by Majid et al. (2016; arXiv:1612.02868). Using these flux density values, we derive a spectral index -0.6(2). We also divided the X-band data into five equal 96 MHz bandwidths and detected pulsations in each subband. Mean flux densities at each subband were measured, and together with our mean flux density value at S

  7. A SHAPIRO DELAY DETECTION IN THE BINARY SYSTEM HOSTING THE MILLISECOND PULSAR PSR J1910-5959A

    Energy Technology Data Exchange (ETDEWEB)

    Corongiu, A.; Burgay, M.; Possenti, A.; D' Amico, N. [INAF-Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, I-09012 Capoterra (Italy); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, 550 West, 120th Street, New York, NY 10027 (United States); Lyne, A. G.; Kramer, M. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Manchester, R. N.; Johnston, S. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia); Sarkissian, J. M. [Australia Telescope National Facility, CSIRO, Parkes Observatory, P.O. Box 276, Parkes, NSW 2870 (Australia); Bailes, M.; Van Straten, W. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218 Hawthorn, VIC 3122 (Australia)

    2012-12-01

    PSR J1910-5959A is a binary pulsar with a helium white dwarf (HeWD) companion located about 6 arcmin from the center of the globular cluster NGC 6752. Based on 12 years of observations at the Parkes radio telescope, the relativistic Shapiro delay has been detected in this system. We obtain a companion mass M{sub C} = 0.180 {+-} 0.018 M {sub Sun} (1{sigma}) implying that the pulsar mass lies in the range 1.1 M {sub Sun} {<=} M{sub P} {<=} 1.5 M {sub Sun }. We compare our results with previous optical determinations of the companion mass and examine prospects for using this new measurement for calibrating the mass-radius relation for HeWDs and for investigating their evolution in a pulsar binary system. Finally, we examine the set of binary systems hosting a millisecond pulsar and a low-mass HeWD for which the mass of both stars has been measured. We confirm that the correlation between the companion mass and the orbital period predicted by Tauris and Savonije reproduces the observed values but find that the predicted M{sub P} -P{sub B} correlation overestimates the neutron star mass by about 0.5 M {sub Sun} in the orbital period range covered by the observations. Moreover, a few systems do not obey the observed M{sub P} -P{sub B} correlation. We discuss these results in the framework of the mechanisms that inhibit the accretion of matter by a neutron star during its evolution in a low-mass X-ray binary.

  8. NuSTAR Observations of the State Transition of Millisecond Pulsar Binary PSR J1023+0038

    DEFF Research Database (Denmark)

    Tendulkar, Shriharsh P.; Yang, Chengwei; An, Hongjun

    2014-01-01

    disappearance of the pulsar, the 3-79 keV X-ray spectrum was well fit by a simple power law with a photon index of Gamma = 1.17(-0.07)(+0.08) (at 90% confidence) with a 3-79 keV luminosity of 7.4 +/- 0.4 x 10(32) erg s(-1). Significant orbital modulation was observed with a modulation fraction of 36% +/- 10......-60 s. No change in hardness ratio was observed during the dips. Consecutive dip separations are log-normal in distribution with a typical separation of approximately 400 s. These dips are distinct from dipping activity observed in LMXBs. We compare and contrast these dips to observations of dips...... and state changes in the similar transition systems PSR J1824-2452I and XSS J1227.0-4859 and discuss possible interpretations based on the transitions in the inner disk....

  9. NuSTAR Observations of the State Transition of Millisecond Pulsar Binary PSR J1023+0038

    DEFF Research Database (Denmark)

    Tendulkar, Shriharsh P.; Yang, Chengwei; An, Hongjun

    2014-01-01

    of the pulsar, the 3-79 keV X-ray spectrum was well fit by a simple power law with a photon index of Gamma=1.17 +/-0.08 (at 90% confidence) with a 3-79 keV luminosity of 7.4+/-0.4 x 10^32 erg/s. Significant orbital modulation was observed with a modulation fraction of 36+/-10%. During the October 19....... Consecutive dip separations are log-normal in distribution with a typical separation of approximately 400 s. These dips are distinct from dipping activity observed in LMXBs. We compare and contrast these dips to observations of dips and state changes in the similar transition systems PSR J1824-2452I and XSS J......1227.0-4859 and discuss possible interpretations based on the transitions in the inner disk....

  10. The Einstein@Home Search for Radio Pulsars and PSR J2007+2722 Discovery

    NARCIS (Netherlands)

    Allen, B.; Knispel, B.; Cordes, J.M.; Deneva, J.S.; Hessels, J.W.T.; Anderson, D.; Aulbert, C.; Bock, O.; Brazier, A.; Chatterjee, S.; Demorest, P.B.; Eggenstein, H.B.; Fehrmann, H.; Gotthelf, E.V.; Hammer, D.; Kaspi, V.M.; Kramer, M.; Lyne, A.G.; Machenschalk, B.; McLaughlin, M.A.; Messenger, C.; Pletsch, H.J.; Ransom, S.M.; Stairs, I.H.; Stappers, B.W.; Bhat, N.D.R.; Bogdanov, S.; Camilo, F.; Champion, D.J.; Crawford, F.; Desvignes, G.; Freire, P.C.C.; Heald, G.; Jenet, F.A.; Lazarus, P.; Lee, K.J.; van Leeuwen, J.; Lynch, R.; Papa, M.A.; Prix, R.; Rosen, R.; Scholz, P.; Siemens, X.; Stovall, K.; Venkataraman, A.; Zhu, W.

    2013-01-01

    Einstein@Home aggregates the computer power of hundreds of thousands of volunteers from 193 countries, to search for new neutron stars using data from electromagnetic and gravitational-wave detectors. This paper presents a detailed description of the search for new radio pulsars using Pulsar ALFA su

  11. The Origin of the Young Pulsar PSR J0826+2637 and Its Possible Former Companion HIP 13962

    CERN Document Server

    Tetzlaff, N; Neuhaeuser, R; Kovtyukh, V V

    2014-01-01

    We aim to identify the birth place of the young pulsar PSR J0826+2637 in order to determine its kinematic age and give constraints on its radial and spatial (kick) velocity. Since the majority of neutron star (NS) progenitors are in associations or clusters, we search for a possible origin of the NS inside such stellar groups. We trace back the NS and the centres of possible birth associations and clusters to find close encounters. The kinematic age is then given by the time since the encounter. We use Monte Carlo simulations to account for observational uncertainties and the unknown radial velocity of the NS. We evaluate the outcome statistically. In order to find further indication for our findings, we also search for a runaway star that could be the former companion if it exists. We find that PSR J0826+2637 was probably born in the small young cluster Stock 7 ~3 Myr ago. This result is supported by the identification of the former companion candidate HIP 13962 (runaway star with spectral type G0Ia). The sc...

  12. A search for X-rays from five pulsars PSR's 0740-28, 1737-30, 1822-09, 1915+13 and 1916+14

    CERN Document Server

    Alpar, M A; Kiziloglu, U; Ögelman, H B; Guseinov, O H; Kiziloglu, Umit; Ogelman, H

    1995-01-01

    We report observations of PSR's 0740-28, 1737-30, 1822-09, 1915+13 and 1916+14 with ROSAT. In the 0.1-2.1 keV range upper limits to luminosity are derived for power law and blackbody spectra, using a range of N_{H} estimates. The upper limit to the blackbody luminosity from PSR1822-09 turns out to be consistent with standard cooling curves. For the other pulsars the upper limits are not restrictive as they are much larger than the luminosities predicted by the models.

  13. NuSTAR Observations of the State Transition of Millisecond Pulsar Binary PSR J1023+0038

    CERN Document Server

    Tendulkar, Shriharsh P; An, Hongjun; Kaspi, Victoria M; Archibald, Anne M; Bassa, Cees; Bellm, Eric; Bogdanov, Slavko; Harrison, Fiona A; Hessels, Jason W T; Janssen, Gemma H; Lyne, Andrew G; Patruno, Alessandro; Stappers, Benjamin; Stern, Daniel; Tomsick, John A; Boggs, Steven E; Chakrabarty, Deepto; Christensen, Finn E; Craig, William W; Hailey, Charles A; Zhang, William

    2014-01-01

    We report NuSTAR observations of the millisecond pulsar - low mass X-ray binary (LMXB) transition system PSR J1023+0038 from June and October 2013, before and after the formation of an accretion disk around the neutron star. Between June 10-12, a few days to two weeks before the radio disappearance of the pulsar, the 3-79 keV X-ray spectrum was well fit by a simple power law with a photon index of Gamma=1.17 +/-0.08 (at 90% confidence) with a 3-79 keV luminosity of 7.4+/-0.4 x 10^32 erg/s. Significant orbital modulation was observed with a modulation fraction of 36+/-10%. During the October 19-21 observation, the spectrum is described by a softer power law (Gamma=1.66+/-0.06) with an average luminosity of 5.8+/-0.2 x 10^33 erg/s and a peak luminosity of ~1.2 x 10^34 erg/s observed during a flare. No significant orbital modulation was detected. The spectral observations are consistent with previous and current multi-wavelength observations and show the hard X-ray power law extending to 79 keV without a spectra...

  14. Constraining the Relative Inclinations of the Planets B and C of the Millisecond Pulsar PSR B1257+12

    Indian Academy of Sciences (India)

    Lorenzo Iorio

    2010-09-01

    We investigate on the relative inclination of the planets B and C orbiting the pulsar PSR B1257+12. First, we show that the third Kepler’s law does represent an adequate model for the orbital periods of the planets, because other Newtonian and Einsteinian corrections are orders of magnitude smaller than the accuracy in measuring B/C. Then, on the basis of available timing data, we determine the ratio sin C/ sin B = 0.92 ± 0.05 of the orbital inclinations B and C independently of the pulsar’s mass . It turns out that coplanarity of the orbits of B and C would imply a violation of the equivalence principle. Adopting a pulsar mass range 1 ≲ ≲ 3, in solar masses (supported by present-day theoretical and observational bounds for pulsar’s masses), both face-on and edge-on orbital configurations for the orbits of the two planets are ruled out; the acceptable inclinations for B span the range 36 deg ≲ B ≲ 66 deg, with a corresponding relative inclination range 6 deg ≲ (C − B) ≲ 13 deg.

  15. POST-PERIASTRON GAMMA-RAY FLARE FROM PSR B1259-63/LS 2883 AS A RESULT OF COMPTONIZATION OF THE COLD PULSAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Khangulyan, Dmitry [Institute of Space and Astronautical Science/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Aharonian, Felix A. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Bogovalov, Sergey V. [Department of Molecular Physics, National Research Nuclear University (MEPHI), Kashirskoe shosse 31, Moscow 115409 (Russian Federation); Ribo, Marc, E-mail: khangul@astro.isas.jaxa.jp, E-mail: felix.aharonian@dias.ie, E-mail: svbogovalov@mephi.ru, E-mail: mribo@am.ub.es [Departament d' Astronomia i Meteorologia, Institut de Ciences del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E-08028 Barcelona (Spain)

    2012-06-10

    We argue that the bright flare of the binary pulsar PSR B1259-63/LS2883 detected by the Fermi Large Area Telescope is due to the inverse Compton scattering of the unshocked electron-positron pulsar wind with a Lorentz factor {Gamma}{sub 0} Almost-Equal-To 10{sup 4}. The combination of two effects both linked to the circumstellar disk (CD) is a key element in the proposed model. The first effect is related to the impact of the surrounding medium on the termination of the pulsar wind. Inside the disk, the 'early' termination of the wind results in suppression of its gamma-ray luminosity. When the pulsar escapes the disk, the conditions for termination of the wind undergo significant changes. This would lead to a dramatic increase of the pulsar wind zone, and thus to the proportional increase of the gamma-ray flux. On the other hand, if the parts of the CD disturbed by the pulsar can supply infrared photons of density high enough for efficient Comptonization of the wind, almost the entire kinetic energy of the pulsar wind would be converted to radiation, thus the gamma-ray luminosity of the wind could approach the level of the pulsar's spin-down luminosity as reported by the Fermi Collaboration.

  16. PSR J1856+0245: Arecibo Discovery of a Young, Energetic Pulsar Coincident with the TeV Gamma-ray Source HESS J1857+026

    CERN Document Server

    Hessels, J W T; Gaensler, B M; Kaspi, V M; Lorimer, D R; Champion, D J; Lyne, A G; Krämer, M; Cordes, J M; Freire, P C C; Camilo, F; Ransom, S M; Deneva, J S; Bhat, N D R; Cognard, I; Crawford, F; Jenet, F A; Kasian, L; Lazarus, P; Van Leeuwen, J; McLaughlin, M A; Stairs, I H; Stappers, B W; Venkataraman, A

    2008-01-01

    We present the discovery of the Vela-like radio pulsar J1856+0245 in the Arecibo PALFA survey. PSR J1856+0245 has a spin period of 81ms, a characteristic age of 21kyr, and a spin-down luminosity Edot = 4.6 x 10^36 ergs/s. It is positionally coincident with the TeV gamma-ray source HESS J1857+026, which has no other known counterparts. Young, energetic pulsars create wind nebulae, and more than a dozen pulsar wind nebulae have been associated with very-high-energy (100GeV-100TeV) gamma-ray sources discovered with the HESS telescope. The gamma-ray emission seen from HESS J1857+026 is potentially produced by a pulsar wind nebula powered by PSR J1856+0245; faint X-ray emission detected by ASCA at the pulsar's position supports this hypothesis. The inferred gamma-ray efficiency is epsilon_gamma = L_gamma/Edot = 3.1% (1-10TeV, for a distance of 9kpc), comparable to that observed in similar associations.

  17. Hard X-ray timing and spectral characteristics of the energetic pulsar PSR J0205+6449 in supernova remnant 3C58

    CERN Document Server

    Kuiper, L; Urama, J O; Hartog, P R den; Lyne, A G; Stappers, B W

    2010-01-01

    PSR J0205+6449 is a young rotation-powered pulsar in SNR 3C 58. It is one of only three young (100 MeV) $\\gamma$-rays. The other two young pulsars are the Crab and PSR B1509-58. Our aim is to derive the timing and spectral characteristics of PSR J0205+6449 over the broad X-ray band from ~0.5 to ~270 keV. We used all publicly available RXTE observations of PSR J0205+6449 to first generate accurate ephemerides over the period September 30, 2000 - March 18, 2006. Next, phase-folding procedures yielded pulse profiles using data from RXTE PCA and HEXTE, and XMM-Newton EPIC PN. While our timing solutions are consistent with earlier results, our work shows sharper structures in the PCA X-ray profile. The X-ray pulse profile consists of two sharp pulses, separated in phase by 0.488(2), which can be described with 2 asymmetric Lorentzians, each with the rising wing steeper than the trailing wing, and full-width-half-maximum 1.41(5) ms and 2.35(22) ms, respectively. We find an indication for a flux increase by a factor...

  18. An X-ray Synchrotron Nebula Associated with the Radio Pulsar PSR B1853+01 in the Supernova Remnant W44

    Science.gov (United States)

    Harrus, I.; Hughes, J. P.

    1995-12-01

    We present results of a study using ASCA X-ray data from the vicinity of the radio pulsar PSR B1853+01 located within the supernova remnant (SNR) W44. PSR B1853+01 is a 267 ms pulsar, which to date has only been detected in the radio band. Previous observations at soft X-ray energies (e.g., ROSAT HRI) have failed to detect any significant X-ray emission (pulsed or unpulsed) from the pulsar. In addition, no high energy tail was seen in the Ginga spectrum of W44 leading to a 3sigma upper limit of 3.6x 10(-12) ergs cm(-2) s(-1) for the 2--10 keV flux of a Crab-like power-law component contributing to the spectrum of W44. Over the 0.5--5 keV band, the ASCA data show soft thermal (kT ~ 0.5 keV) emission from W44 with a morphology very similar to that observed before by Einstein and ROSAT. In the high energy band (5--10 keV) the SNR for the most part is not visible and instead an unresolved source coincident with the position of PSR B1853+01 is evident. The observed ASCA spectra are consistent with a power-law origin (photon index ~ 3.5) for the X-ray emission from this source at a flux level below the Ginga upper limit. The maximum allowed size for the source is determined directly from the ASCA data (1.5(') ). We also report on our timing analysis, which failed to detect pulsations from the X-ray source at the pulsar's period. Based on these lines of evidence, we suggest that the new hard source in W44 represents the X-ray synchrotron nebula surrounding PSR B1853+01, rather than the beamed output of the pulsar itself. The ratio of the nebula's X-ray luminosity to the spin-down energy loss of the pulsar is consistent with that of other known plerions, lending further support to our interpretation. This is the first indirect detection in the X-ray band of the pulsar associated with W44.

  19. NuSTAR observations of the state transition of millisecond pulsar binary PSR J1023+0038

    Energy Technology Data Exchange (ETDEWEB)

    Tendulkar, Shriharsh P.; Bellm, Eric; Harrison, Fiona A. [California Institute of Technology, 1200 E California Blvd, MC 249-17, Pasadena, CA 91125 (United States); Yang, Chengwei; An, Hongjun; Kaspi, Victoria M. [Department of Physics, McGill University, 3600 University St, Montreal, QC H3A 2T8 (Canada); Archibald, Anne M.; Bassa, Cees; Hessels, Jason W. T.; Janssen, Gemma H. [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Lyne, Andrew G.; Stappers, Benjamin [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Patruno, Alessandro [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Tomsick, John A.; Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Chakrabarty, Deepto [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States); Christensen, Finn E., E-mail: spt@astro.caltech.edu [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); and others

    2014-08-20

    We report NuSTAR observations of the millisecond pulsar-low-mass X-ray binary (LMXB) transition system PSR J1023+0038 from 2013 June and October, before and after the formation of an accretion disk around the neutron star. Between June 10 and 12, a few days to two weeks before the radio disappearance of the pulsar, the 3-79 keV X-ray spectrum was well fit by a simple power law with a photon index of Γ=1.17{sub −0.07}{sup +0.08} (at 90% confidence) with a 3-79 keV luminosity of 7.4 ± 0.4 × 10{sup 32} erg s{sup –1}. Significant orbital modulation was observed with a modulation fraction of 36% ± 10%. During the October 19-21 observation, the spectrum is described by a softer power law (Γ=1.66{sub −0.05}{sup +0.06}) with an average luminosity of 5.8 ± 0.2 × 10{sup 33} erg s{sup –1} and a peak luminosity of ≈1.2 × 10{sup 34} erg s{sup –1} observed during a flare. No significant orbital modulation was detected. The spectral observations are consistent with previous and current multiwavelength observations and show the hard X-ray power law extending to 79 keV without a spectral break. Sharp-edged, flat-bottomed dips are observed with widths between 30 and 1000 s and ingress and egress timescales of 30-60 s. No change in hardness ratio was observed during the dips. Consecutive dip separations are log-normal in distribution with a typical separation of approximately 400 s. These dips are distinct from dipping activity observed in LMXBs. We compare and contrast these dips to observations of dips and state changes in the similar transition systems PSR J1824–2452I and XSS J1227.0–4859 and discuss possible interpretations based on the transitions in the inner disk.

  20. A Chandra X-Ray observation of the binary millisecond pulsar PSR J1023+0038

    NARCIS (Netherlands)

    Bogdanov, S.; Archibald, A.M.; Hessels, J.W.T.; Kaspi, V.M.; Lorimer, D.; McLaughlin, M.A.; Ransom, S.M.; Stairs, I.H.

    2011-01-01

    We present a Chandra X-Ray Observatory ACIS-S variability, spectroscopy, and imaging study of the peculiar binary containing the millisecond pulsar J1023+0038. The X-ray emission from the system exhibits highly significant (12.5σ) large-amplitude (factor of two to three) orbital variability over the

  1. PSR J1930-1852: a pulsar in the widest known orbit around another neutron star

    CERN Document Server

    Swiggum, J K; McLaughlin, M A; Lorimer, D R; Heatherly, S; Lynch, R; Scoles, S; Hockett, T; Filik, E; Marlowe, J A; Barlow, B N; Weaver, M; Hilzendeger, M; Ernst, S; Crowley, R; Stone, E; Miller, B; Nunez, R; Trevino, G; Doehler, M; Cramer, A; Yencsik, D; Thorley, J; Andrews, R; Laws, A; Wenger, K; Teter, L; Snyder, T; Dittmann, A; Gray, S; Carter, M; McGough, C; Dydiw, S; Pruett, C; Fink, J; Vanderhout, A

    2015-01-01

    In the summer of 2012, during a Pulsar Search Collaboratory workshop, two high-school students discovered J1930$-$1852, a pulsar in a double neutron star (DNS) system. Most DNS systems are characterized by short orbital periods, rapid spin periods and eccentric orbits. However, J1930$-$1852 has the longest spin period ($P_{\\rm spin}\\sim$185 ms) and orbital period ($P_{\\rm b}\\sim$45 days) yet measured among known, recycled pulsars in DNS systems, implying a shorter than average and/or inefficient recycling period before its companion went supernova. We measure the relativistic advance of periastron for J1930$-$1852, $\\dot{\\omega}=0.00078$(4) deg/yr, which implies a total mass (M$_{\\rm{tot}}=2.59$(4) M$_{\\odot}$) consistent with other DNS systems. The $2\\sigma$ constraints on M$_{\\rm{tot}}$ place limits on the pulsar and companion masses ($m_{\\rm p}1.30$ M$_{\\odot}$ respectively). J1930$-$1852's spin and orbital parameters challenge current DNS population models and make J1930$-$1852 an important system for fur...

  2. Discovery of an X-Ray Synchrotron Nebula Associated with the Radio Pulsar PSR B1853+01 in the Supernova Remnant W44

    Science.gov (United States)

    Harrus, Ilana M.; Hughes, John P.; Helfand, David J.

    1996-06-01

    We report the detection, using data from the Advanced Satellite for Cosmology and Astrophysics (ASCA), of a hard X-ray source in the vicinity of the radio pulsar PSR B1853+01, which is located within the supernova remnant (SNR) W44. PSR B1853+01, a 267 ms pulsar, has to date been detected only in the radio band. Previous observations at soft X-ray energies (e.g., with ROSAT HRI) have failed to detect any significant X-ray emission (pulsed or unpulsed) from the pulsar. In addition, no high-energy emission (>~4 keV) has been detected previously from W44. Over the 0.5--4.0 keV band, the ASCA data show soft thermal emission from W44, with a morphology very similar to that observed earlier by Einstein and ROSAT. In the high-energy band (4.0--9.5 keV), the SNR is, for the most part, invisible, although a source coincident with the position of PSR B1853+01 is evident. The observed ASCA spectra are consistent with a power-law origin (photon index ~2.3) for the X-ray emission from this source at a flux level (flux density ~0.5 mu Jy at 1 keV) consistent with previous upper limits. The maximum allowed size for the source is determined directly from the ASCA data (~30"). Timing analysis of the hard X-ray source failed to detect pulsations at the pulsar's period. Based on these lines of evidence, we conclude that the new hard source in W44 represents an X-ray synchrotron nebula associated with PSR B1853+01, rather than the beamed output of the pulsar itself. This discovery adds W44 to the small group of previously known plerionic SNRs. This nebula lies at the low end of, but is consistent with, the correlation between X-ray luminosity and pulsar spin-down energy loss found for such objects, lending further support to our interpretation.

  3. DISCOVERY OF PSR J1227−4853: A TRANSITION FROM A LOW-MASS X-RAY BINARY TO A REDBACK MILLISECOND PULSAR

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Jayanta; Bhattacharyya, Bhaswati; Stappers, Ben [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, M13 9PL (United Kingdom); Ray, Paul S.; Wolff, Michael; Wood, Kent S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Chengalur, Jayaram N. [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411 007 (India); Deneva, Julia [NRC Research Associate, resident at Naval Research Laboratory, Washington, DC 20375-5352 (United States); Camilo, Fernando [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Johnson, Tyrel J. [College of Science, George Mason University, Fairfax, VA 22030, USA, resident at Naval Research Laboratory, Washington, DC 20375 (United States); Hessels, Jason W. T.; Bassa, Cees G. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Keane, Evan F. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Mail H30, P.O. Box 218, VIC 3122 (Australia); Ferrara, Elizabeth C.; Harding, Alice K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2015-02-10

    XSS J12270−4859 is an X-ray binary associated with the Fermi Large Area Telescope gamma-ray source 1FGL J1227.9−4852. In 2012 December, this source underwent a transition where the X-ray and optical luminosity dropped and the spectral signatures of an accretion disk disappeared. We report the discovery of a 1.69 millisecond pulsar (MSP), PSR J1227−4853, at a dispersion measure of 43.4 pc cm{sup −3} associated with this source, using the Giant Metrewave Radio Telescope (GMRT) at 607 MHz. This demonstrates that, post-transition, the system hosts an active radio MSP. This is the third system after PSR J1023+0038 and PSR J1824−2452I showing evidence of state switching between radio MSP and low-mass X-ray binary states. We report timing observations of PSR J1227−4853 with the GMRT and Parkes, which give a precise determination of the rotational and orbital parameters of the system. The companion mass measurement of 0.17–0.46 M{sub ⊙} suggests that this is a redback system. PSR J1227−4853 is eclipsed for about 40% of its orbit at 607 MHz with additional short-duration eclipses at all orbital phases. We also find that the pulsar is very energetic, with a spin-down luminosity of ∼10{sup 35} erg s{sup −1}. We report simultaneous imaging and timing observations with the GMRT, which suggests that eclipses are caused by absorption rather than dispersion smearing or scattering.

  4. Exploring the X-ray and gamma-ray properties of the redback millisecond pulsar PSR J1723-2837

    CERN Document Server

    Hui, C Y; Takata, J; Kong, A K H; Cheng, K S; Wu, J H K; Lin, L C C; Wu, E M H

    2013-01-01

    We have investigated the X-ray and $\\gamma$-ray properties of the redback millisecond pulsar PSR J1723-2837 with XMM-Newton, Chandra and Fermi. We have discovered the X-ray orbital modulation of this binary system with the minimum that coincides with the phases of radio eclipse. The X-ray emission is clearly non-thermal in nature which can be well described by a simple power-law with a photon index of $\\sim1.2$. The phase-averaged luminosity is $\\sim9\\times10^{31}$ erg/s in 0.3-10 keV which consumes $\\sim0.2\\%$ of the spin-down power. We have detected the $\\gamma-$ray emission in $0.1-300$ GeV from this system at a significance of $\\sim6\\sigma$ for the first time. The $\\gamma-$rays in this energy range consumes $\\sim2\\%$ of the spin-down power and can be modeled by a power-law with a photon index of $\\sim2.6$. We discuss the high energy properties of the new redback in the context of a intrabinary shock model.

  5. Simultaneous Observations of Giant Pulses from Pulsar PSR B0950+08 at 42 MHz and 74 MHz

    CERN Document Server

    Tsai, Jr-Wei; Akukwe, Bernadine; Bear, Brandon; Gough, Jonathan D; Shawhan, Peter; Kavic, Michael

    2016-01-01

    We report the detection of giant pulse emission from PSR~B0950+08 in 12 hours of observations made simultaneously at 42~MHz and 74~MHz, using the first station of the Long Wavelength Array, LWA1. We detected 275 giant pulses (in 0.16\\% of the pulse periods) and 465 giant pulses (0.27\\%) at 42 and 74~MHz, respectively. The pulsar is weaker and produces less frequent giant pulses than at 100~MHz. Here, giant pulses are taken as having $\\geq$ 10 times the flux density of an average pulse; their cumulative distribution of pulse strength follows a power law, with a index of $-$4.1 at 42~MHz and $-$5.1 at 74~MHz, which is much less steep than would be expected if we were observing the tail of a Gaussian distribution of normal pulses. We detected no other transient pulses in a wide dispersion measure range from 1 to 5000~pc~cm$^{-3}$. There were 128 giant pulses detected within in the same periods from both 42 and 74~MHz, which means more than half of them are not generated in a wide band. We use CLEAN-based algorit...

  6. GMRT DISCOVERY OF PSR J1544+4937: AN ECLIPSING BLACK-WIDOW PULSAR IDENTIFIED WITH A FERMI-LAT SOURCE

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, B.; Roy, J.; Gupta, Y. [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411 007 (India); Ray, P. S.; Wolff, M. T.; Wood, K. S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Bhattacharya, D. [Inter-University Centre for Astronomy and Astrophysics, Pune 411 007 (India); Romani, R. W.; Den Hartog, P. R.; Kerr, M.; Michelson, P. F. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Ransom, S. M. [National Radio Astronomy Observatory (NRAO), Charlottesville, VA 22903 (United States); Ferrara, E. C.; Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement, LPCE UMR 6115 CNRS, F-45071 Orleans Cedex 02 (France); Johnston, S.; Keith, M. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping, NSW 1710 (Australia); Saz Parkinson, P. M. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Wood, D. L. [Praxis Inc., Alexandria, VA 22303 (United States)

    2013-08-10

    Using the Giant Metrewave Radio Telescope, we performed deep observations to search for radio pulsations in the directions of unidentified Fermi-Large Area Telescope {gamma}-ray sources. We report the discovery of an eclipsing black-widow millisecond pulsar, PSR J1544+4937, identified with the uncataloged {gamma}-ray source FERMI J1544.2+4941. This 2.16 ms pulsar is in a 2.9 hr compact circular orbit with a very low mass companion (M{sub c} > 0.017M{sub Sun }). At 322 MHz this pulsar is found to be eclipsing for 13% of its orbit, whereas at 607 MHz the pulsar is detected throughout the low-frequency eclipse phase. Variations in the eclipse ingress phase are observed, indicating a clumpy and variable eclipsing medium. Moreover, additional short-duration absorption events are observed around the eclipse boundaries. Using the radio timing ephemeris we were able to detect {gamma}-ray pulsations from this pulsar, confirming it as the source powering the {gamma}-ray emission.

  7. A physical scenario for the high and low X-ray luminosity states in the transitional pulsar PSR J1023+0038

    Science.gov (United States)

    Campana, S.; Coti Zelati, F.; Papitto, A.; Rea, N.; Torres, D. F.; Baglio, M. C.; D'Avanzo, P.

    2016-10-01

    The binary system PSR J1023+0038 (J1023) hosts a neutron star and a low-mass companion. J1023 is the best studied transitional pulsar, alternating a faint eclipsing millisecond radio pulsar state to a brighter X-ray active state. At variance with other low-mass X-ray binaries, this active state reaches luminosities of only ~1034 erg s-1, showing strong, fast variability. In the active state, J1023 displays: i) a high state (LX ~ 7 × 1033 erg s-1, 0.3-80 keV) occurring ~80% of the time and during which X-ray pulsations at the neutron star spin period are detected (pulsed fraction ~ 8%); ii) a low state (LX ~ 1033 erg s-1) during which pulsations are not detected (≲ 3%); and iii) a flaring state during which sporadic flares occur in excess of ~ 1034 erg s-1, with no pulsation too. The transition between the high and the low states is very rapid, on a ~10 s timescale. Here we propose a plausible physical interpretation of the high and low states based on the (fast) transition among the propeller state and the radio pulsar state. We modelled the XMM-Newton spectra of the high, low and radio pulsar states, and found a good agreement with this physical picture.

  8. Variability, polarimetry, and timing properties of single pulses from PSR J1713+0747 using the Large European Array for Pulsars

    CERN Document Server

    Liu, K; Janssen, G H; Karuppusamy, R; McKee, J; Kramer, M; Lee, K J; Perrodin, D; Purver, M; Sanidas, S; Smits, R; Stappers, B W; Weltevrede, P; Zhu, W W

    2016-01-01

    Single pulses preserve information about the pulsar radio emission and propagation in the pulsar magnetosphere, and understanding the behaviour of their variability is essential for estimating the fundamental limit on the achievable pulsar timing precision. Here we report the findings of our analysis of single pulses from PSR J1713+0747 with data collected by the Large European Array for Pulsars (LEAP). We present statistical studies of the pulse properties that include distributions of their energy, phase and width. Two modes of systematic sub-pulse drifting have been detected, with a periodicity of 7 and 3 pulse periods. The two modes appear at different ranges of pulse longitude but overlap under the main peak of the integrated profile. No evidence for pulse micro-structure is seen with a time resolution down to 140 ns. In addition, we show that the fractional polarisation of single pulses increases with their pulse peak flux density. By mapping the probability density of linear polarisation position angle...

  9. Variability, polarimetry, and timing properties of single pulses from PSR J1713+0747 using the Large European Array for Pulsars

    Science.gov (United States)

    Liu, K.; Bassa, C. G.; Janssen, G. H.; Karuppusamy, R.; McKee, J.; Kramer, M.; Lee, K. J.; Perrodin, D.; Purver, M.; Sanidas, S.; Smits, R.; Stappers, B. W.; Weltevrede, P.; Zhu, W. W.

    2016-12-01

    Single pulses preserve information about the pulsar radio emission and propagation in the pulsar magnetosphere, and understanding the behaviour of their variability is essential for estimating the fundamental limit on the achievable pulsar timing precision. Here we report the findings of our analysis of single pulses from PSR J1713+0747 with data collected by the Large European Array for Pulsars (LEAP). We present statistical studies of the pulse properties that include distributions of their energy, phase and width. Two modes of systematic sub-pulse drifting have been detected, with a periodicity of seven and three pulse periods. The two modes appear at different ranges of pulse longitude but overlap under the main peak of the integrated profile. No evidence for pulse micro-structure is seen with a time resolution down to 140 ns. In addition, we show that the fractional polarization of single pulses increases with their pulse peak flux density. By mapping the probability density of linear polarization position angle with pulse longitude, we reveal the existence of two orthogonal polarization modes. Finally, we find that the resulting phase jitter of integrated profiles caused by single pulse variability can be described by a Gaussian probability distribution only when at least 100 pulses are used for integration. Pulses of different flux densities and widths contribute approximately equally to the phase jitter, and no improvement on timing precision is achieved by using a sub-set of pulses with a specific range of flux density or width.

  10. Different twins in the millisecond pulsar recycling scenario: optical polarimetry of PSR J1023+0038 and XSS J12270-4859

    CERN Document Server

    Baglio, M C; Campana, S; Zelati, F Coti; Covino, S; Russell, D M

    2016-01-01

    We present the first optical polarimetric study of the two transitional pulsars PSR J1023+0038 and XSS J12270-4859. This work is focused on the search for intrinsical linear polarisation (LP) in the optical emission from the two systems. We carried out multiband optical and NIR photo-polarimetry of the two systems using the ESO NTT at La Silla (Chile), equipped with the EFOSC2 and the SOFI instruments. XSS J12270-4859 was observed during its radio-pulsar state; we did not detect LP in all bands, with 3 sigma upper limits of, e.g., 1.4% in the R-band. We built the NIR-optical averaged spectral energy distribution (SED) of the system, that could be well described by an irradiated black body with radius $R_{*} = 0.33\\pm0.03\\,R_{\\odot}$ and albedo $\\eta=0.32\\pm0.05$, without the need of further components (thus excluding the visible presence of an extended accretion disc and/or of relativistic jets). The case was different for PSR J1023+0038, that was in its accretion phase during our campaign. We measured a LP o...

  11. Gamma-ray emission from globular clusters. Shock high energy emission from the Be-Star/Pulsar System PSR 1259-63. Echoes in x-ray novae

    Science.gov (United States)

    Kaaret, Philip

    1995-01-01

    This grant covers work on the Compton phase 3 investigation, 'Shock High Energy Emission from the Be- Star/Pulsar System PSR 1259-63' and cycle 4 investigations 'Diffuse Gamma-Ray Emission at High Latitudes' and 'Echoes in X-Ray Novae'. Work under the investigation 'Diffuse Gamma-Ray Emission at High Latitudes' has lead to the publication of a paper (attached), describing gamma-ray emissivity variations in the northern galactic hemisphere. Using archival EGRET data, we have found a large irregular region of enhanced gamma-ray emissivity at energies greater 100 MeV. This is the first observation of local structure in the gamma-ray emissivity. Work under the investigation 'Echoes in X-Ray Novae' is proceeding with analysis of data from OSSE from the transient source GRO J1655-40. The outburst of this source last fall triggered this Target of Opportunity investigation. Preliminary spectral analysis shows emission out to 600 keV and a pure power low spectrum with no evidence of an exponential cutoff. Work is complete on the analysis of BATSE data from the Be-Star/Pulsar Sustem PSR 1259-63.

  12. Discovery of the Binary Pulsar PSR B1259-63 in Very-High-Energy Gamma Rays around Periastron with H.E.S.S

    CERN Document Server

    Aharonian, F; Aye, K M; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Berghaus, P; Bernlöhr, K; Boisson, C; Bolz, O; Braun, I; Breitling, F; Brown, A M; Bussons-Gordo, J; Chadwick, P M; Chounet, L M; Cornils, R; Costamante, L; Degrange, B; Djannati-Ata, A; O'Connor-Drury, L; Dubus, G; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Fleury, P; Fontaine, G; Fuchs, Y; Funk, S; Gallant, Y A; Giebels, B; Gillessen, S; Glicenstein, J F; Goret, P; Hadjichristidis, C; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hofmann, W; Holleran, M; Horns, D; De Jager, O C; Johnston, S; Khelifi, B; Kirk, J G; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemiere, A; Lemoine-Goumard, M; Leroy, N; Martineau-Huynh, O; Lohse, T; Marcowith, A; Masterson, C; McComb, T J L; De Naurois, Mathieu; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Raux, J; Rayner, S M; Redondo, I; Reimer, A; Reimer, O; Ripken, J; Rob, L; Rolland, L; Rowell, G; Sahakian, V V; Sauge, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Skjraasen, O; Sol, H; Steenkamp, R; Stegmann, C; Tavernet, J P; Terrier, R; Theoret, C G; Tluczykont, M; Vasileiadis, G; Venter, C; Vincent, P; Völk, H J; Wagner, S J

    2005-01-01

    We report the discovery of very-high-energy (VHE) gamma-ray emission of the binary system PSR B1259-63/SS 2883 of a radio pulsar orbiting a massive, luminous Be star in a highly eccentric orbit. The observations around the 2004 periastron passage of the pulsar were performed with the four 13 m Cherenkov telescopes of the H.E.S.S. experiment, recently installed in Namibia and in full operation since December 2003. Between February and June 2004, a gamma-ray signal from the binary system was detected with a total significance above 13 sigma. The flux was found to vary significantly on timescales of days which makes PSR B1259-63 the first variable galactic source of VHE gamma-rays observed so far. Strong emission signals were observed in pre- and post-periastron phases with a flux minimum around periastron, followed by a gradual flux decrease in the months after. The measured time-averaged energy spectrum above a mean threshold energy of 380 GeV can be fitted by a simple power law F_0(E/1 TeV)^-Gamma with a phot...

  13. Fermi Study of 5-300 GeV emission from the high-mass pulsar binary PSR B1259-63/LS 2883

    CERN Document Server

    Xing, Yi; Takata, Jumpei

    2016-01-01

    We report the results from our detailed analysis of the Fermi Large Area Telescope (LAT) data for the pulsar binary PSR B1259-63/LS 2883. During the GeV flares that occurred when the pulsar was in the periastron passages, we have detected a 5--300 GeV component at $\\simeq 5\\sigma$ in emission from the binary. The detection verifies the presence of the component that has been marginally found in the previous studies of the binary. Furthermore, we have discovered that this component was present even in the quiescent state of the binary, specifically the mean anomaly phase 0.7--0.9. The component can be described by a power law with photon index $\\Gamma\\sim 1.4$, and the flux in the flares is approximately one order of magnitude higher than that in quiescence. We discuss the origin of this component. It likely arises from the inverse-Compton process: high-energy particles from the shock, due to the interaction between the winds from the pulsar and massive companion, scatter the seed photons from the companion to...

  14. Fermi Study of 5--300 GeV Emission from the High-mass Pulsar Binary PSR B1259-63/LS 2883

    Science.gov (United States)

    Xing, Yi; Wang, Zhongxiang; Takata, Jumpei

    2016-09-01

    We report the results from our detailed analysis of the Fermi Large Area Telescope data for the pulsar binary PSR B1259-63/LS 2883. During the GeV flares that occurred when the pulsar was in the periastron passages, we have detected a 5-300 GeV component at ≃5σ in emission from the binary. The detection verifies the presence of the component that has been marginally found in previous studies of the binary. Furthermore, we have discovered that this component was marginally present even in the quiescent state of the binary, specifically the mean anomaly phase 0.7-0.9. The component can be described by a power law with a photon index Γ ˜ 1.4, and the flux in the flares is approximately one order of magnitude higher than that in quiescence. We discuss the origin of this component. It likely arises from the inverse-Compton process: due to the interaction between the winds from the pulsar and its massive companion, high-energy particles from the shock scatter the seed photons from the companion to GeV/TeV energies. Based on this scenario, model fits to the broad-band X-ray to TeV spectra of the binary in the flaring and quiescent states are provided.

  15. Modeling the Multiwavelength Light Curves of PSR B1259-63/LS 2883. II. The Effects of Anisotropic Pulsar Wind and Doppler Boosting

    Science.gov (United States)

    Kong, S. W.; Cheng, K. S.; Huang, Y. F.

    2012-07-01

    PSR B1259-63/LS 2883 is a binary system in which a 48 ms pulsar orbits around a Be star in a high eccentric orbit with a long orbital period of about 3.4 yr. It is special for having asymmetric two-peak profiles in both the X-ray and TeV light curves. Recently, an unexpected GeV flare has been detected by the Fermi gamma-ray observatory several weeks after the last periastron passage. In this paper, we show that this observed GeV flare could be produced by the Doppler-boosted synchrotron emission in the bow-shock tail. An anisotropic pulsar wind model, which mainly affects the energy flux injection into the termination shock in a different orbital phase, is also used in this paper, and we find that the anisotropy in the pulsar wind can play a significant role in producing the asymmetric two-peak profiles in both X-ray and TeV light curves. The X-ray and TeV photons before periastron are mainly produced by the shocked electrons around the shock apex, and the light curves after periastron are contributed by the emission from the shock apex and the shock tail together, which result in asymmetric two-peak light curves.

  16. Broadband Pulsations from PSR B1821-24: Implications for Emission Models and the Pulsar Population of M28

    CERN Document Server

    Johnson, T J; Kerr, M; Cognard, I; Ray, P S; Wolff, M T; Begin, S; Janssen, G H; Romani, R W; Venter, C; Grove, J E; Freire, P C C; Wood, M; Cheung, C C; Casandjian, J M; Stairs, I H; Camilo, F; Espinoza, C M; Ferrara, E C; Harding, A K; Johnston, S; Kramer, M; Lyne, A G; Michelson, P F; Ransom, S M; Shannon, R; Smith, D A; Stappers, B W; Theureau, G; Thorsett, S E

    2013-01-01

    We report a 5.4\\sigma\\ detection of pulsed gamma rays from PSR B1821-24 in the globular cluster M28 using ~44 months of Fermi Large Area Telescope (LAT) data that have been reprocessed with improved instrument calibration constants. We constructed a phase-coherent ephemeris, with post-fit residual RMS of 3 \\mu s, using radio data spanning ~23.2 years, enabling measurements of the multi-wavelength light curve properties of PSR B1821-24 at the milliperiod level. We fold RXTE observations of PSR B1821-24 from 1996 to 2007 and discuss implications on the emission zones. The gamma-ray light curve consists of two peaks, separated by 0.41$\\pm$0.02 in phase, with the first gamma-ray peak lagging the first radio peak by 0.05$\\pm$0.02 in phase, consistent with the phase of giant radio pulses. We observe significant emission in the off-peak interval of PSR B1821-24 with a best-fit LAT position inconsistent with the core of M28. We do not detect significant gamma-ray pulsations at the spin or orbital periods from any oth...

  17. The Inclination Angle and Evolution of the Braking Index of Pulsars with Plasma-filled Magnetosphere: Application to the High Braking Index of PSR J1640-4631

    Science.gov (United States)

    Ekşi, K. Y.; Andaç, I. C.; Çıkıntoğlu, S.; Gügercinoğlu, E.; Vahdat Motlagh, A.; Kızıltan, B.

    2016-05-01

    The recently discovered rotationally powered pulsar PSR J1640-4631 is the first to have a braking index measured, with high enough precision, that is greater than 3. An inclined magnetic rotator in vacuum or plasma would be subject not only to spin-down but also to an alignment torque. The vacuum model can address the braking index only for an almost orthogonal rotator, which is incompatible with the single-peaked pulse profile. The magnetic dipole model with the corotating plasma predicts braking indices between 3 and 3.25. We find that the braking index of 3.15 is consistent with two different inclination angles, 18.°5 ± 3° and 56° ± 4°. The smaller angle is preferred given that the pulse profile has a single peak and the radio output of the source is weak. We infer the change in the inclination angle to be at the rate -0.°23 per century, three times smaller in absolute value than the rate recently observed for the Crab pulsar.

  18. Inclination angle and braking index evolution of pulsars with plasma-filled magnetosphere: application to high braking index of PSR J1640-4631

    CERN Document Server

    Ekşi, Kazım Yavuz; Çıkıntoğlu, Sercan; Gügercinoğlu, Erbil; Motlagh, Armin Vahdat; Kızıltan, Bülent

    2016-01-01

    The recently discovered rotationally powered pulsar PSR J1640-4631 is the first to have a braking index measured, with high enough precision, to be greater than three. An inclined magnetic rotator in vacuum or plasma would be subject to not only spin-down torque but also to an alignment torque. The vacuum model can address the braking index only for an almost orthogonal rotator which is incompatible with the single peaked pulse profile. We show that the magnetic dipole model with the corotating plasma predicts braking indices between $3-3.25$ and can explain the braking index of $3.15$ for two different inclination angles, $18.5\\pm 3$ degrees and $56 \\pm 4$ degrees. Of these the former is preferred given the pulse profile has a single peak. We infer the change in the inclination angle to be at the rate $-0.23$ degrees per century, three times smaller in absolute value than the rate recently observed from the Crab pulsar.

  19. A physical scenario for the high and low X-ray luminosity states in the transitional pulsar PSR J1023+0038

    CERN Document Server

    Campana, S; Papitto, A; Rea, N; Torres, D F; Baglio, M C; D'Avanzo, P

    2016-01-01

    PSR J1023+0038 (J1023) is a binary system hosting a neutron star and a low mass companion. J1023 is the best studied transitional pulsar, alternating a faint eclipsing millisecond radio pulsar state to a brighter X-ray active state. At variance with other Low Mass X-ray binaries, this active state reaches luminosities of only ~$10^{34}$ erg s$^{-1}$, showing strong, fast variability. In the active state, J1023 displays: i) a high state ($L_X\\sim7\\times10^{33}$ erg s$^{-1}$, 0.3-80 keV) occurring ~80% of the time and during which X-ray pulsations at the neutron star spin period are detected (pulsed fraction ~8%); ii) a low state ($L_X~10^{33}$ erg s$^{-1}$) during which pulsations are not detected (~<3%); and iii) a flaring state during which sporadic flares occur in excess of ~$10^{34}$ erg s$^{-1}$, with no pulsation too. The transition between the high and the low states is very rapid, on a ~10 s timescale. Here we put forward a plausible physical interpretation of the high and low states based on the (f...

  20. Pulse intensity modulation and the timing stability of millisecond pulsars: A case study of PSR J1713+0747

    CERN Document Server

    Shannon, Ryan M

    2012-01-01

    Most millisecond pulsars, like essentially all other radio pulsars, show timing errors well in excess of what is expected from additive radiometer noise alone. We show that changes in amplitude, shape and pulse phase for the millisecond pulsar J1713+0747 cause this excess error. These changes appear to be uncorrelated from one pulse period to the next. The resulting time of arrival variations are correlated across a wide frequency range and are observed with different backend processors on different days, confirming that they are intrinsic in origin and not an instrumental effect or caused by strongly frequency dependent interstellar scattering. Centroids of single pulses show an rms phase variation \\approx 40 microsec, which dominates the timing error and is the same phase jitter phenomenon long known in slower spinning, canonical pulsars. We show that the amplitude modulations of single pulses are modestly correlated with their arrival time fluctuations. We also demonstrate that single-pulse variations are ...

  1. First Detection of a Pulsar Bow Shock Nebula in Far-UV: PSR J0437-4715

    Science.gov (United States)

    Rangelov, Blagoy; Pavlov, George G.; Kargaltsev, Oleg; Durant, Martin; Bykov, Andrei M.; Krassilchtchikov, Alexandre

    2016-11-01

    Pulsars traveling at supersonic speeds are often accompanied by cometary bow shocks seen in Hα. We report on the first detection of a pulsar bow shock in the far-ultraviolet (FUV). We detected it in FUV images of the nearest millisecond pulsar J0437-4715 obtained with the Hubble Space Telescope. The images reveal a bow-like structure positionally coincident with part of the previously detected Hα bow shock, with an apex at 10″ ahead of the moving pulsar. Its FUV luminosity, L(1250{--}2000 \\mathringA )≈ 5 × {10}28 erg s-1, exceeds the Hα luminosity from the same area by a factor of 10. The FUV emission could be produced by the shocked interstellar medium matter or, less likely, by relativistic pulsar wind electrons confined by strong magnetic field fluctuations in the bow shock. In addition, in the FUV images we found a puzzling extended (≃3″ in size) structure overlapping with the limb of the bow shock. If related to the bow shock, it could be produced by an inhomogeneity in the ambient medium or an instability in the bow shock. We also report on a previously undetected X-ray emission extending for about 5″ ahead of the pulsar, possibly a pulsar wind nebula created by shocked pulsar wind, with a luminosity L(0.5-8 keV) ˜ 3 × 1028 erg s-1. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs GO 12917 and GO 10568.

  2. Discovery of a faint X-ray counterpart and of a parsec-long X-ray tail for the middle-aged, gamma-ray only pulsar PSR J0357+3205

    CERN Document Server

    De Luca, A; Mignani, R P; Caraveo, P A; Hummel, W; Collins, S; Shearer, A; Parkinson, P M Saz; Belfiore, A; Bignami, G F

    2011-01-01

    The Large Area Telescope (LAT) onboard the Fermi satellite opened a new era for pulsar astronomy, detecting gamma-ray pulsations from more than 60 pulsars, ~40% of which are not seen at radio wavelengths. One of the most interesting sources discovered by LAT is PSR J0357+3205, a radio-quiet, middle-aged (tau_C ~0.5 Myr) pulsar standing out for its very low spin-down luminosity (Erot ~6x10^33 erg/s), indeed the lowest among non-recycled gamma-ray pulsars. A deep X-ray observation with Chandra (0.5-10 keV), coupled with sensitive optical/infrared ground-based images of the field, allowed us to identify PSR J0357+3205 as a faint source with a soft spectrum, consistent with a purely non-thermal emission (photon index Gamma=2.53+/-0.25). The absorbing column (NH=8+/-4x10^20 cm^-2) is consistent with a distance of a few hundred parsecs. Moreover, the Chandra data unveiled a huge (9 arcmin long) extended feature apparently protruding from the pulsar. Its non-thermal X-ray spectrum points to synchrotron emission from...

  3. NuSTAR Hard X-ray Observations of the Energetic Millisecond Pulsars PSR B1821-24, PSR B1937+21, and PSR J0218+4232

    Science.gov (United States)

    Gotthelf, Eric V.; Bogdanov, Slavko

    2017-08-01

    We present NuSTAR hard X-ray timing and spectroscopy of the three exceptionally energetic rotation-powered millisecond pulsars PSRs B1821-24, B1937+21, and J0218+4232. By correcting for frequency and phase drifts of the NuSTAR on-board clock we are able to recover the intrinsic hard X-ray pulse profiles of all three pulsars with a resolution down to up to ~50 keV, ~20 keV, and ~25 keV, for the three pulsars, respectively. We conduct phase-resolved spectroscopy in the 0.5 - 79 keV range for all three objects, obtaining the best yet measurements of the broad-band spectral shape and high-energy pulsed emission to date. We find extensions of the same power-law continua seen at lower energies, with no conclusive evidence for a spectral turnover or break. Extrapolation of the X-ray power-law spectrum to higher energies reveals that a turnover in the 100 keV to 100 MeV range is required to accommodate the high energy gamma-ray emission observed with Fermi LAT, similar to the broad-band spectral energy distribution observed for the Crab pulsar.

  4. Different twins in the millisecond pulsar recycling scenario: Optical polarimetry of PSR J1023+0038 and XSS J12270-4859

    Science.gov (United States)

    Baglio, M. C.; D'Avanzo, P.; Campana, S.; Coti Zelati, F.; Covino, S.; Russell, D. M.

    2016-06-01

    We present the first optical polarimetric study of the two transitional pulsars PSR J1023+0038 and XSS J12270-4859. This work is focused on the search for intrinsically linearly polarised optical emission from the two systems. To this aim, we carried out multiband optical (BVRi) and near-infrared (NIR; JHK) photo-polarimetric observations of the two systems using the ESO New Technology Telescope (NTT) at La Silla (Chile), equipped with the EFOSC2 and the SOFI instruments. The system XSS J12270-4859 was observed during its radio-pulsar state; we did not detect a significant degree of polarisation in any of the bands, with 3σ upper limits, for example, of 1.4% in the R-band. We built the NIR-optical averaged spectral energy distribution (SED) of the system, which could be described well by an irradiated black body with radius R∗ = 0.33 ± 0.03 R⊙ and albedo η = 0.32 ± 0.05, without the need for further components. Thus, we excluded the visible presence of an extended accretion disc and/or of relativistic jets. The case was different for PSR J1023+0038, which was in its accretion phase during our campaign. We measured a linear polarisation of 1.09 ± 0.27% and 0.90 ± 0.17% in the V and R bands, respectively. The phase-resolved polarimetric curve of the source in the R band reveals a hint of a sinusoidal modulation at the source 4.75 h orbital period, peaked at the same orbital phase as the light curve. The measured optical polarisation of PSR J1023+0038 could, in principle, be interpreted as electron scattering with free electrons, which can be found in the accretion disc of the system or even in the hot corona that sorrounds the disc itself, or as synchrotron emission from a jet of relativistic particles or an outflow. However, the NIR-optical SED of the system built from our dataset did not suggest the presence of a jet. We conclude that the optical linear polarisation observed for PSR J1023+0038 is possibly due to Thomson scattering with electrons in the

  5. On quasiperiodic variations of pulsars' periods - An alternative to the planetary interpretation of PSR1257+12

    Science.gov (United States)

    Dolginov, A. Z.; Stepinski, T. F.

    1993-01-01

    The quasi-periodic timing residuals of PSR1257+12 are considered to be a result of two large-scale internal motions of the neutron star: core-crust relative motion and precession. The model requires that the superfluid core of a neutron star is not pinned to the solid crust. A very good fit to the observations is obtained for the set of parameters that corresponds to a nearly orthogonal rotator, and the period of the core-crust relative rotation that is nearly twice the period of precession.

  6. The evolutionary status of the white dwarf companion of the binary pulsar PSR J1713+0747

    CERN Document Server

    Benvenuto, O G; De Vito, M A

    2006-01-01

    Splaver and coworkers have measured the masses of the white dwarf and the neutron star components of the PSR J1713+0747 binary system pair by Shapiro Delay. We attempt to find the original configuration of this system performing a set of binary evolution calculations to simultaneously account for the masses of both stars and the orbital period. We considered initial masses of 1.5 and 1.4 \\msun for the normal (donor) and the neutron star, respectively. We assumed two metallicity values (Z = 0.010 and 0.020), and an initial orbital period near 3 days. We assume that the neutron star is only able to retain \\lesssim 0.10 of the matter transferred by the donor star. Calculations were performed employing our binary hydro code that handles the mass transfer rate in a fully implicit way together with state-of-the-art physical ingredients, diffusion and a non-grey atmospheres. We compare the structure of the resulting white dwarfs with the characteristic age of PSR J1713+0747 finding a nice agreement with observations...

  7. The relativistic pulsar-white dwarf binary PSR J1738+0333 II. The most stringent test of scalar-tensor gravity

    CERN Document Server

    Freire, Paulo C C; Esposito-Farèse, Gilles; Verbiest, Joris P W; Bailes, Matthew; Jacoby, Bryan A; Kramer, Michael; Stairs, Ingrid H; Antoniadis, John; Janssen, Gemma H

    2012-01-01

    (abridged) We report the results of a 10-year timing campaign on PSR J1738+0333, a 5.85-ms pulsar in a low-eccentricity 8.5-hour orbit with a low-mass white dwarf companion (...) The measurements of proper motion and parallax allow for a precise subtraction of the kinematic contribution to the observed orbital decay; this results in a significant measurement of the intrinsic orbital decay: (-25.9 +/- 3.2) \\times 10^{-15} s/s. This is consistent with the orbital decay from the emission of gravitational waves predicted by general relativity, (-27.7 +1.5/-1.9) \\times 10^{-15} s/s (...). This agreement introduces a tight upper limit on dipolar gravitational wave emission, a prediction of most alternative theories of gravity for asymmetric binary systems such as this. We use this limit to derive the most stringent constraints ever on a wide class of gravity theories, where gravity involves a scalar field contribution. When considering general scalar-tensor theories of gravity, our new bounds are more stringent tha...

  8. PSR J2021+4026 in the Gamma Cygni region: the first variable gamma-ray pulsar seen by the Fermi LAT

    CERN Document Server

    ,

    2013-01-01

    Long-term monitoring of PSR J2021+4026 in the heart of the Cygnus region with the Fermi Large Area Telescope (LAT) unveiled a sudden decrease in flux above 100 MeV over a time scale shorter than a week. The "jump" was near MJD 55850 (2011 October 16), with the flux decreasing from $(8.33\\pm0.08) \\times 10^{-10}$ erg cm$^{-2}$ s$^{-1}$ to $(6.86\\pm0.13) \\times 10^{-10}$ erg cm$^{-2}$ s$^{-1}$. Simultaneously, the frequency spindown rate increased from $(7.8\\pm 0.1) \\times 10^{-13}$ Hz s$^{-1}$ to $(8.1\\pm 0.1) \\times 10^{-13}$ Hz s$^{-1}$. Significant changes in the pulse profile and marginal changes in the emission spectrum occurred at the same time. There is also evidence for a small, steady flux increase over the three years preceding MJD 55850. This is the first observation at gamma-ray energies of mode changes and intermittent behavior, observed at radio wavelengths for other pulsars. We argue that the change in pulsed gamma-ray emission is due to a change in emission beaming and we speculate that it is p...

  9. The evolutionary status of the white dwarf companion of the binary pulsar PSR J1713+0747

    Science.gov (United States)

    Benvenuto, O. G.; Rohrmann, R. D.; De Vito, M. A.

    2006-03-01

    Recently Splaver et al. have measured the masses of the white dwarf and the neutron star (NS) components of the PSR J1713+0747 binary system pair by means of the general relativistic effect known as Shapiro delay with very high accuracy. Employing these data we attempt to find the original configuration that evolved to the observed system. For this purpose we perform a set of binary evolution calculations trying to simultaneously account for the masses of both stars and the orbital period. In doing so, we considered normal (donor) stars with an initial mass of 1.5Msolar, while for the neutron star companion we assumed a mass of 1.4Msolar. We assumed two metallicity values for the donor star (Z= 0.010 and 0.020) and that the initial orbital period was nearly 3d. In order to get a good agreement between the masses of the models and observations we had to assume that the NS is only able to retain Benvenuto & De Vito, that handles the mass transfer rate in a fully implicit way together with state-of-the-art physical ingredients and diffusion processes. Now our code also includes a detailed non-grey treatment for the atmospheres of white dwarfs (WDs). We compare the structure of the resulting WDs with the characteristic age of PSR J1713+0747 finding a nice agreement with observations by Lundgren et al. especially for the case of a donor star with Z= 0.010. This result indicates that, at least for the purposes of this paper, the evolution of this kind of binary system is fairly well understood. The models predict that, due to diffusion, the atmosphere of the white dwarf is an almost hydrogen-pure one. We find that such structures are unable to account for the colours measured by Lundgren et al. within their error bars. Thus, in spite of the very good agreement of the model with the main characteristics of the system, we find that some discrepancies in the WD emergent radiation remain to be explained.

  10. Simultaneous Observations of Giant Pulses from Pulsar PSR B0031-07 at 38 MHz and 74 MHz

    CERN Document Server

    Tsai, Jr-Wei; Bear, Brandon; Gough, Jonathan D; Newton, Joseph R; Kavic, Michael

    2016-01-01

    The first station of the Long Wavelength Array (LWA1) was used to study PSR~B0031-07 with simultaneous observations at 38 and 74~MHz. We found that 158 (0.35\\%) of the observed pulses at 38~MHz and 221 (0.49\\%) of the observed pulses at 74~MHz qualified as giant pulses in a total of 12 hours of observations. Giant pulses are defined as having flux densities of a factor of $\\geq$ 90 times that of an average pulse at 38~MHz and $\\geq$ 80 times that of an average pulse at 74~MHz. The cumulative distribution of pulse strength follows a power law, with an index of $-$4.2 at 38~MHz and $-$4.9 at 74~MHz. This distribution has a much more gradual slope than would be expected if observing the tail of a Gaussian distribution of normal pulses. The dispersion measure value which resulted in the largest signal-to-noise for dedispersed pulses was DM $=10.9$~pc~cm$^{-3}$. No other transient pulses were detected in the data in the wide dispersion measure range from 1 to 5000~pc~cm$^{-3}$. There were 12 giant pulses detected ...

  11. PSR J2021+4026 IN THE GAMMA CYGNI REGION: THE FIRST VARIABLE γ-RAY PULSAR SEEN BY THE Fermi LAT

    Energy Technology Data Exchange (ETDEWEB)

    Allafort, A.; Bottacini, E.; Cameron, R. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L. [Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa (Italy); Ballet, J.; Chaves, R.C.G. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d' Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Baring, M. G. [Rice University, Department of Physics and Astronomy, MS-108, P. O. Box 1892, Houston, TX 77251 (United States); Bastieri, D.; Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bonamente, E.; Cecchi, C. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bruel, P. [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France); Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Caliandro, G. A. [Institut de Ciències de l' Espai (IEEE-CSIC), Campus UAB, E-08193 Barcelona (Spain); Caraveo, P. A. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Chekhtman, A., E-mail: ltibaldo@slac.stanford.edu, E-mail: massimiliano.razzano@pi.infn.it [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030, resident at Naval Research Laboratory, Washington, DC 20375 (United States); and others

    2013-11-01

    Long-term monitoring of PSR J2021+4026 in the heart of the Cygnus region with the Fermi Large Area Telescope unveiled a sudden decrease in flux above 100 MeV over a timescale shorter than a week. The 'jump' was near MJD 55850 (2011 October 16), with the flux decreasing from (8.33 ± 0.08) × 10{sup –10} erg cm{sup –2} s{sup –1} to (6.86 ± 0.13) × 10{sup –10} erg cm{sup –2} s{sup –1}. Simultaneously, the frequency spindown rate increased from (7.8 ± 0.1) × 10{sup –13} Hz s{sup –1} to (8.1 ± 0.1) × 10{sup –13} Hz s{sup –1}. Significant (>5σ) changes in the pulse profile and marginal (<3σ) changes in the emission spectrum occurred at the same time. There is also evidence for a small, steady flux increase over the 3 yr preceding MJD 55850. This is the first observation at γ-ray energies of mode changes and intermittent behavior, observed at radio wavelengths for other pulsars. We argue that the change in pulsed γ-ray emission is due to a change in emission beaming and we speculate that it is precipitated by a shift in the magnetic field structure, leading to a change of either effective magnetic inclination or effective current.

  12. PSR J2021+4026 in the Gamma Cygni Region: The First Variable Gamma-Ray Pulsar Seen by the Fermi LAT

    Science.gov (United States)

    Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bellazzini, R.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; D’Ammando, F.; Harding, A. K.; Hays, E.; Hewitt, J.; Thompson, D. J.

    2013-01-01

    Long-term monitoring of PSR J2021+4026 in the heart of the Cygnus region with the Fermi Large Area Telescope unveiled a sudden decrease in flux above 100 MeV over a timescale shorter than a week. The "jump" was near MJD 55850 (2011 October 16), with the flux decreasing from (8.33 plus or minus 0.08)×10(exp -10) erg cm(exp -2) s(exp -1) to (6.86 plus or minus 0.13)× 10 (exp -1)0 erg cm (exp -2) s(exp -1). Simultaneously, the frequency spindown rate increased from (7.8 plus or minus 0.1) × 10(exp -13) Hz s(exp -1) to (8.1 plus or minus 0.1) × 10(exp -1)3 Hz s(exp -1). Significant (greater than 5 sigma) changes in the pulse profile and marginal (less than 3 sigma) changes in the emission spectrum occurred at the same time. There is also evidence for a small, steady flux increase over the 3 yr preceding MJD 55850. This is the first observation at gamma-ray energies of mode changes and intermittent behavior, observed at radio wavelengths for other pulsars. We argue that the change in pulsed gamma-ray emission is due to a change in emission beaming and we speculate that it is precipitated by a shift in the magnetic field structure, leading to a change of either effective magnetic inclination or effective current.

  13. Pulsars in FIRST Observations

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We identify 16 pulsars from the Survey of Faint Images of the Radio Sky at Twenty-cm (FIRST) at 1.4 GHz. Their positions and total flux densities are extracted from the FIRST catalog. By comparing the source positions with those in the PSR catalog, we obtain better determined positions of PSR J1022+1001,J1518+4904, J1652+2651, and proper motion upper limits of PSR J0751+1807,J1012+5307, and J1640+2224. The proper motions of the other ten pulsars are consistent with the catalog values.

  14. Revisiting the Westerlund 2 Field with the H.E.S.S. Telescope Array

    CERN Document Server

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Barnacka, A; de Almeida, U Barres; Bazer-Bachi, A R; Becherini, Y; Becker, J; Behera, B; Bernlöhr, K; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Borrel, V; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Boutelier, T; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Conrad, J; Chounet, L -M; Clapson, A C; Coignet, G; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fiasson, A; Förster, A; Fontaine, G; Füßling, M; Gabici, S; Gallant, Y A; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göring, D; Hague, J D; Hampf, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Hofverberg, P; Holleran, M; Hoppe, S; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jung, I; Katarzyński, K; Katz, U; Kaufmann, S; Kerschhaggl, M; Khangulyan, D; Khélifi, B; Keogh, D; Klochkov, D; Kluźniak24, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Lamanna, G; Lenain, J -P; Lennarz, D; Lohse, T; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, D; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Moulin, E; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Olive, J-F; Wilhelmi, E de Oña; Opitz, B; Orford, K J; Ostrowski, M; Panter, M; Arribas, M Paz; Pedaletti1, G; Pelletier, G; Petrucci, P -O; Pita1, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Rayner, S M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger1, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Ryde, F; Sahakian, V; Santangelo, A; Schlickeiser, R; Schöck, F M; Schönwald, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sushch, I; Sikora, M; Skilton, J L; Sol, H; Spengler, G; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Szostek, A; Tam, P H; Tavernet, J -P; Terrier, R; Tibolla, O; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Vialle, J P; Viana, A; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Vorobiov, S; Wagner, S J; Ward, M; Zdziarski, A A; Zech, A; Zechlin, H -S; Fukui, Y; Furukawa, N; Ohama, A; Sano, H; Dawson, J; Kawamura, A

    2010-01-01

    Aims. Previous observations with the H.E.S.S. telescope array revealed the existence of extended very-high-energy (VHE; E>100 GeV) {\\gamma}-ray emission, HESS J1023-575, coincident with the young stellar cluster Westerlund 2. At the time of discovery, the origin of the observed emission was not unambiguously identified, and follow-up observations have been performed to further investigate the nature of this {\\gamma}-ray source. Methods. The Carina region towards the open cluster Westerlund 2 has been re-observed, increasing the total exposure to 45.9 h. The combined dataset includes 33 h of new data and now permits a search for energy-dependent morphology and detailed spectroscopy. Results. A new, hard spectrum VHE {\\gamma}-ray source, HESSJ1026-582, was discovered with a statistical significance of 7{\\sigma}. It is positionally coincident with the Fermi LAT pulsar PSR J1028-5819. The positional coincidence and radio/{\\gamma}-ray characteristics of the LAT pulsar favors a scenario where the TeV emission origi...

  15. PSR J2030+364I: Radio Discovery and Gamma-ray Study of a Middle-aged Pulsar in the Now Identified Fermi-LAT Source 1FGL J2030.0+3641

    Science.gov (United States)

    Camilo, F.; Kerr, M.; Ray, P. S.; Ransom, S. M.; Johnston, S.; Romani, R. W.; Parent, D.; Decesar, M. E.; Harding, A. K.; Donato, D.; SazParkinson, P. M.; Ferrara, E. C.; Freire, P. C. C.; Guillemot, L; Keith, M.; Kramer, M.; Wood, K. S.

    2011-01-01

    In a radio search with the Green Bank Telescope of three unidentified low Galactic latitude Fermi-LAT sources, we have discovered the middle-aged pulsar J2030+3641, associated with IFGL J2030.0+3641 (2FGL J2030.0+3640). Following the detection of gamma-ray pulsations using a radio ephemeris, we have obtained a phase-coherent timing solution based on gamma-ray and radio pulse arrival times that spans the entire Fermi mission. With a rotation period of 0.28, spin-down luminosity of 3 x 10(exp 34) erg/s, and characteristic age of 0.5 Myr, PSR J2030+3641 is a middle-aged neutron star with spin parameters similar to those of the exceedingly gamma-ray-bright and radio-undetected Geminga. Its gamma-ray flux is 1 % that of Geminga, primarily because of its much larger distance, as suggested by the large integrated column density of free electrons, DM = 246 pc/cu cm. We fit the gamma-ray light curve, along with limited radio polarimetric constraints, to four geometrical models of magnetospheric emission, and while none of the fits have high significance some are encouraging and suggest that further refinements of these models may be worthwhile. We argue that not many more non-millisecond radio pulsars may be detected along the Galactic plane that are responsible for LAT sources, but that modified methods to search for gamma-ray pulsations should be productive - PSR J2030+364 I would have been found blindly in gamma rays if only > or approx. 0.8 GeV photons had been considered, owing to its relatively flat spectrum and location in a region of high soft background.

  16. Binary and Millisecond Pulsars

    Directory of Open Access Journals (Sweden)

    Lorimer Duncan R.

    2008-11-01

    Full Text Available We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1800. There are now 83 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 140 pulsars in 26 of the Galactic globular clusters. Recent highlights include the discovery of the young relativistic binary system PSR J1906+0746, a rejuvination in globular cluster pulsar research including growing numbers of pulsars with masses in excess of 1.5M_⊙, a precise measurement of relativistic spin precession in the double pulsar system and a Galactic millisecond pulsar in an eccentric (e = 0.44 orbit around an unevolved companion.

  17. 78 Pairs of Possible PSR-SNR Associations

    CERN Document Server

    Su, Hongquan; Zhu, Hui; Tian, Wen-Wu

    2013-01-01

    We discuss the criteria to associate PSRs with SNRs, and summary 78 pairs of possible PSR-SNR associations which is the most complete sample so far. We refine them into three categories according to degree of reliability. Statistic study on PSR-SNR associations helps us understand massive star evolution and constrain pulsar's theory models.

  18. Revisiting the Westerlund 2 field with the HESS telescope array

    Science.gov (United States)

    H.E.S.S. Collaboration; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barnacka, A.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y.; Becker, J.; Behera, B.; Bernlöhr, K.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Borrel, V.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Büsching, I.; Boutelier, T.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Conrad, J.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; Drury, L. O'C.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Förster, A.; Fontaine, G.; Füßling, M.; Gabici, S.; Gallant, Y. A.; Gérard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Göring, D.; Hague, J. D.; Hampf, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Holleran, M.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jung, I.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Kerschhaggl, M.; Khangulyan, D.; Khélifi, B.; Keogh, D.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Lamanna, G.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, D.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; Olive, J.-F.; de Oña Wilhelmi, E.; Opitz, B.; Orford, K. J.; Ostrowski, M.; Panter, M.; Paz Arribas, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Reimer, O.; Reimer, A.; Renaud, M.; de los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Ryde, F.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schöck, F. M.; Schönwald, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sushch, I.; Sikora, M.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Szostek, A.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; Tibolla, O.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Vialle, J. P.; Vincent, P.; Vivier, M.; Völk, H. J.; Volpe, F.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.; Fukui, Y.; Furukawa, N.; Ohama, A.; Sano, H.; Dawson, J.; Kawamura, A; H.E.S.S. Collaboration

    2011-01-01

    Aims: Previous observations with the HESS telescope array revealed the existence of extended very-high-energy (VHE; E>100 GeV) γ-ray emission, HESS J1023-575, coincident with the young stellar cluster Westerlund 2. At the time of discovery, the origin of the observed emission was not unambiguously identified, and follow-up observations have been performed to further investigate the nature of this γ-ray source. Methods: The Carina region towards the open cluster Westerlund 2 has been re-observed, increasing the total exposure to 45.9 h. The combined dataset includes 33 h of new data and now permits a search for energy-dependent morphology and detailed spectroscopy. Results: A new, hard spectrum VHE γ-ray source, HESS J1026-582, was discovered with a statistical significance of 7σ. It is positionally coincident with the Fermi LAT pulsar PSR J1028-5819. The positional coincidence and radio/γ-ray characteristics of the LAT pulsar favors a scenario where the TeV emission originates from a pulsar wind nebula. The nature of HESS J1023-575 is discussed in light of the deep HESS observations and recent multi-wavelength discoveries, including the Fermi LAT pulsar PSR J1022-5746 and giant molecular clouds in the region. Despite the improved VHE dataset, a clear identification of the object responsible for the VHE emission from HESS J1023-575 is not yet possible, and contribution from the nearby high-energy pulsar and/or the open cluster remains a possibility.

  19. A digital pulsar backend based on FPGA

    Science.gov (United States)

    Luo, Jin-Tao; Chen, Lan; Han, Jin-Lin; Esamdin, Ali; Wu, Ya-Jun; Li, Zhi-Xuan; Hao, Long-Fei; Zhang, Xiu-Zhong

    2017-01-01

    A digital pulsar backend based on a Field Programmable Gate Array (FPGA) is developed. It is designed for incoherent de-dispersion of pulsar observations and has a maximum bandwidth of 512 MHz. The channel bandwidth is fixed to 1 MHz, and the highest time resolution is 10 {{μ }} s. Testing observations were carried out using the Urumqi 25-m telescope administered by Xinjiang Astronomical Observatory and the Kunming 40-m telescope administered by Yunnan Observatories, targeting PSR J0332+5434 in the L band and PSR J0437–4715 in the S band, respectively. The successful observation of PSR J0437–4715 demonstrates its ability to observe millisecond pulsars.

  20. Fermi LAT Detection of Early Post-Periastron Increased GeV Gamma-Ray Emission From The Be-Pulsar Binary System PSR B1259-63

    Science.gov (United States)

    Johnson, T. J.; Wood, K. S.; Ray, P. S.; K, M. T.

    2017-10-01

    Using data from the Large Area Telescope (LAT), one of the two instruments on board the Fermi Gamma-ray Space Telescope, we have detected > 100 MeV flux enhancement from PSR B1259-63, in a 3.4 yr binary orbit with a Be star, on three consecutive days (2017-10-01 06:24:04 UTC through 2017-10-04 06:37:41 UTC), with approximate significances of 4.7, 3.0, and 3.8 sigma and photon fluxes (from 100 MeV to 300 GeV) of (13.6 +/- 3.4), (8.4 +/- 3.3), and (10.0 +/- 3.0) x 10^-7 ph/cm^2/s, respectively.

  1. Near-IR observations of PSR J1357-6429

    CERN Document Server

    Zyuzin, D; Shibanov, Yu; Danilenko, A; Mennickent, R E; Kirichenko, A

    2015-01-01

    PSR J1357$-$6429 is a young radio pulsar that was detected in X-rays and $\\gamma$-rays. We present the high spatial resolution near-infrared imaging of the pulsar field in $J$, $H$ and $K_s$ bands obtained with the VLT/NaCo using the Adaptive Optic system. We found a faint source at the most precise pulsar radio position which we propose as the pulsar near-infrared counterpart candidate. It is confidently detected in the $J$ and $K_s$ bands, with $J$ = 23.51$\\pm$0.24 and $K_s$ = 21.82$\\pm$0.25. There is a hint of the source in the $H$ band with an upper limit $H$ $>$ 22.8. The dereddened source fluxes are compatible with the extrapolation of the pulsar X-ray spectrum towards the near-infrared. If the candidate is the true counterpart, by this property PSR J1357$-$6429 would be similar to the nearby middle-age pulsar PSR B0656+14. In this case, both pulsars demonstrate an unusually high near-infrared efficiency relative to the X-ray efficiency as compared to other pulsars detected in both ranges.

  2. Pulsar lensing geometry

    CERN Document Server

    Liu, Siqi; Macquart, J-P; Brisken, Walter; Deller, Adam

    2015-01-01

    Our analysis of archival VLBI data of PSR 0834+06 revealed that its scintillation properties can be precisely modelled using the inclined sheet model (Pen & Levin 2014), resulting in two distinct lens planes. These data strongly favour the grazing sheet model over turbulence as the primary source of pulsar scattering. This model can reproduce the parameters of the observed diffractive scintillation with an accuracy at the percent level. Comparison with new VLBI proper motion results in a direct measure of the ionized ISM screen transverse velocity. The results are consistent with ISM velocities local to the PSR 0834+06 sight-line (through the Galaxy). The simple 1D structure of the lenses opens up the possibility of using interstellar lenses as precision probes for pulsar lens mapping, precision transverse motions in the ISM, and new opportunities for removing scattering to improve pulsar timing. We describe the parameters and observables of this double screen system. While relative screen distances can i...

  3. Constraint on Parameters of Inverse Compton Scattering Model for PSR B2319+60

    Indian Academy of Sciences (India)

    H. G. Wang; M. Lv

    2011-03-01

    Using the multifrequency radio profiles of pulsar PSR B2319+60, two parameters of inverse Compton scattering model, the initial Lorentz factor and the factor of energy loss of relativistic particles are constrained.

  4. Hyperfast pulsars as the remnants of massive stars ejected from young star clusters

    NARCIS (Netherlands)

    Gvaramadze, V.V.; Gualandris, A.; Portegies Zwart, S.

    2008-01-01

    Recent proper motion and parallax measurements for the pulsar PSR B1508+55 indicate a transverse velocity of similar to 1100 km s(-1), which exceeds earlier measurements for any neutron star. The spin-down characteristics of PSR B1508+55 are typical for a non-recycled pulsar, which implies that the

  5. Revisiting the Magnetic and Spin Evolution of Two Young X-ray Pulsars

    Science.gov (United States)

    Ferdman, Robert; Kaspi, Victoria M.; Archibald, Robert Frederic

    2014-08-01

    We present results from timing analysis of two young X-ray pulsars found in the large Magellanic Cloud: the Crab-like energetic pulsar PSR B0540-69 and the so-called "big glitcher", PSR J0537-6910. In both cases, we analyze data taken with the Rossi X-ray Timing Explorer. This work extends the published data sets for these pulsars by approximately doubling their respective data spans. We revisit the glitching activity of these neutron stars, particularly that of PSR J0537-6910, determine more precise glitch and spin parameters, and discuss the implications for the spin and magnetospheric evolution of these interesting pulsars.

  6. PSR J1738+0333: a new gravitational laboratory

    CERN Document Server

    Freire, Paulo C C; Bailes, Matthew

    2007-01-01

    We describe in this paper a new binary millisecond pulsar, PSR J1738+0333. Using Arecibo, we have achieved good timing accuracy for this object, about 220 ns for 1-hour integrations over 100 MHz. This allowed us to measure a precise proper motion, parallax and orbital parameters for this system. We highlight the system's potential for constraining alternative theories of gravitation.

  7. Gamma radiation from PSR B1055-52

    DEFF Research Database (Denmark)

    Thompson, D.J.; Bailes, M.; Bertsch, D.L.

    1999-01-01

    The telescopes on the Compton Gamma Ray Observatory (CGRO) have observed PSR B1055-52 a number of times between 1991 and 1998. From these data a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics that distinguish this pulsar: the light...

  8. Very High Energy Observations of PSR B1951+32

    CERN Document Server

    Srinivasan, R; Buckley, J H; Burdett, A M; Gordo, J B; Carter-Lewis, D A; Cawley, M F; Catanese, M; Colombo, E; Fegan, D J; Finley, J P; Gaidos, J A; Hillas, A M; Lamb, R C; Krennrich, F; Lessard, R W; Masterson, C; McEnery, J E; Mohanty, G B; Moriarty, P; Quinn, J; Rodgers, A J; Rose, H J; Samuelson, F W; Sembroski, G H; Weekes, T C; Zweerink, J A

    1997-01-01

    PSR B1951+32 is a gamma-ray pulsar detected by the Energetic Gamma Ray Experiment Telescope (EGRET) and identified with the 39.5 ms radio pulsar in the supernova remnant CTB 80. The EGRET data shows no evidence for a spectral turnover. Here we report on the first observations of PSR B1951+32 beyond 30 GeV. The observations were carried out with the 10m gamma-ray telescope at the Whipple Observatory on Mt. Hopkins, Arizona. In 8.1 hours of observation we find no evidence for steady or periodic emission from PSR B1951+32 above ~260 GeV. FLux upper limits are derived and compared with model extrapolations from lower energies and the predictions of emission models.

  9. Radio-quiet Gamma-ray Pulsars

    Science.gov (United States)

    Lin, Lupin Chun-Che

    2016-09-01

    A radio-quiet γ-ray pulsar is a neutron star that has significant γ-ray pulsation but without observed radio emission or only limited emission detected by high sensitivity radio surveys. The launch of the Fermi spacecraft in 2008 opened a new epoch to study the population of these pulsars. In the 2nd Fermi Large Area Telescope catalog of γ-ray pulsars, there are 35 (30 % of the 117 pulsars in the catalog) known samples classified as radio-quiet γ-ray pulsars with radio flux density (S1400) of less than 30 μJy. Accompanying the observations obtained in various wavelengths, astronomers not only have the opportunity to study the emitting nature of radio-quiet γ-ray pulsars but also have proposed different models to explain their radiation mechanism. This article will review the history of the discovery, the emission properties, and the previous efforts to study pulsars in this population. Some particular cases known as Geminga-like pulsars (e.g., PSR J0633+1746, PSR J0007+7303, PSR J2021+4026, and so on) are also specified to discuss their common and specific features.

  10. Modelling interaction of relativistic and non-relativistic winds in binary system PSR B1259-63/SS2883 - II. Impact of magnetization and anisotropy of the pulsar wind

    CERN Document Server

    Bogovalov, S; Koldoba, A V; Ustyugova, G V; Aharonian, F A

    2011-01-01

    In this paper, we present a numerical study of the properties of the flow produced by the collision of a magnetized anisotropic pulsar wind with its environment in binary system. We compare the impact of both the magnetic field and the wind anisotropy to the benchmark case of a purely hydrodynamical (HD) interaction of isotropic winds, which has been studied in detail by Bogovalov et al. (2008). We consider the interaction in axisymmetric approximation, i.e. the pulsar rotation axis is assumed to be oriented along the line between the pulsar and the optical star and the effects related to the pulsar orbiting are neglected. The impact of the magnetic field is studied for the case of weak magnetization (with magnetization parameter $\\sigma<0.1$), which is consistent with conventional models of pulsar winds. The effects related to anisotropy in pulsar winds are modeled assuming that the kinetic energy flux in a non-magnetized pulsar wind is strongly anisotropic, with the minimum at the pulsar rotation axis an...

  11. The spin evolution of young pulsars

    CERN Document Server

    Espinoza, Cristobal M

    2012-01-01

    The current understanding of the spin evolution of young pulsars is reviewed through a compilation of braking index measurements. An immediate conclusion is that the spin evolution of all pulsars with a measured braking index is not purely caused by a constant magnetic dipole. The case of PSR J1734-3333 and its upward movement towards the magnetars is used as a guide to try to understand why pulsars evolve with n < 3. Evolution between different pulsar families, driven by the emergence of a hidden internal magnetic field, appears as one possible picture.

  12. Pulsar Discovery by Global Volunteer Computing

    Science.gov (United States)

    Knispel, B.; Allen, B.; Cordes, J. M.; Deneva, J. S.; Anderson, D.; Aulbert, C.; Bhat, N. D. R.; Bock, O.; Bogdanov, S.; Brazier, A.; Camilo, F.; Champion, D. J.; Chatterjee, S.; Crawford, F.; Demorest, P. B.; Fehrmann, H.; Freire, P. C. C.; Gonzalez, M. E.; Hammer, D.; Hessels, J. W. T.; Jenet, F. A.; Kasian, L.; Kaspi, V. M.; Kramer, M.; Lazarus, P.; van Leeuwen, J.; Lorimer, D. R.; Lyne, A. G.; Machenschalk, B.; McLaughlin, M. A.; Messenger, C.; Nice, D. J.; Papa, M. A.; Pletsch, H. J.; Prix, R.; Ransom, S. M.; Siemens, X.; Stairs, I. H.; Stappers, B. W.; Stovall, K.; Venkataraman, A.

    2010-09-01

    Einstein@Home aggregates the computer power of hundreds of thousands of volunteers from 192 countries to mine large data sets. It has now found a 40.8-hertz isolated pulsar in radio survey data from the Arecibo Observatory taken in February 2007. Additional timing observations indicate that this pulsar is likely a disrupted recycled pulsar. PSR J2007+2722’s pulse profile is remarkably wide with emission over almost the entire spin period; the pulsar likely has closely aligned magnetic and spin axes. The massive computing power provided by volunteers should enable many more such discoveries.

  13. Pulsar Discovery by Global Volunteer Computing

    CERN Document Server

    Knispel, B; Cordes, J M; Deneva, J S; Anderson, D; Aulbert, C; Bhat, N D R; Bock, O; Bogdanov, S; Brazier, A; Camilo, F; Champion, D J; Chatterjee, S; Crawford, F; Demorest, P B; Fehrmann, H; Freire, P C C; Gonzalez, M E; Hammer, D; Hessels, J W T; Jenet, F A; Kasian, L; Kaspi, V M; Kramer, M; Lazarus, P; van Leeuwen, J; Lorimer, D R; Machenschalk, A G Lyne B; McLaughlin, M A; Messenger, C; Nice, D J; Papa, M A; Pletsch, H J; Prix, R; Ransom, S M; Siemens, X; Stairs, I H; Stappers, B W; Stovall, K; Venkataraman, A

    2010-01-01

    Einstein@Home aggregates the computer power of hundreds of thousands of volunteers from 192 countries to "mine" large data sets. It has now found a 40.8 Hz isolated pulsar in radio survey data from the Arecibo Observatory taken in February 2007. Additional timing observations indicate that this pulsar is likely a disrupted recycled pulsar. PSR J2007+2722's pulse profile is remarkably wide with emission over almost the entire spin period; the pulsar likely has closely aligned magnetic and spin axes. The massive computing power provided by volunteers should enable many more such discoveries.

  14. Eclipsing Binary Pulsars

    CERN Document Server

    Freire, P C C

    2004-01-01

    The first eclipsing binary pulsar, PSR B1957+20, was discovered in 1987. Since then, 13 other eclipsing low-mass binary pulsars have been found, 12 of these are in globular clusters. In this paper we list the known eclipsing binary pulsars and their properties, with special attention to the eclipsing systems in 47 Tuc. We find that there are two fundamentally different groups of eclipsing binary pulsars; separated by their companion masses. The less massive systems (M_c ~ 0.02 M_sun) are a product of predictable stellar evolution in binary pulsars. The systems with more massive companions (M_c ~ 0.2 M_sun) were formed by exchange encounters in globular clusters, and for that reason are exclusive to those environments. This class of systems can be used to learn about the neutron star recycling fraction in the globular clusters actively forming pulsars. We suggest that most of these binary systems are undetectable at radio wavelengths.

  15. Possible optical counterpart of PSR J1357--6429

    CERN Document Server

    Danilenko, A; Mennickent, R E; Pavlov, G; Shibanov, Yu; Zharikov, S; Zyuzin, D

    2012-01-01

    PSR J1357--6429 is a Vela-like radio pulsar that has been recently detected in X-rays and gamma-rays. It powers a compact tail-like X-ray pulsar wind nebula and X-ray-radio plerion associated with an extended TeV source HESS J1356--645. We have performed deep optical observations with the VLT to search for an optical counterpart of the pulsar and its nebula. A point-like source has been detected in V, R, and I bands whose centre position is within the 1-sigma error circle of the X-ray position of the pulsar, and whose colours are distinct from those of ordinary stars. We consider it as a candidate optical counterpart of the pulsar. If it is indeed the counterpart, its 5-sigma offset from the radio pulsar position, measured about 9 yr earlier, implies the transverse velocity of the pulsar in the range of 1600--2000 km s^{-1} at the distance of 2--2.5 kpc, making it the fastest moving pulsar known. The direction of the estimated proper motion coincides with the extension of the pulsar's X-ray tail, suggesting t...

  16. The Millisecond Pulsars in NGC 6760

    CERN Document Server

    Freire, P C C; Nice, D J; Ransom, S M; Lorimer, D R; Stairs, I H; Freire, Paulo C. C.; Hessels, Jason W. T.; Nice, David J.; Ransom, Scott M.; Lorimer, Duncan R.; Stairs, Ingrid H.

    2004-01-01

    We present the results of recent Arecibo and Green Bank observations of the globular cluster NGC 6760. Using Arecibo, a phase-coherent timing solution has been obtained for the previously known binary pulsar in this cluster, PSR J1911+0102A. We have also discovered a new millisecond pulsar in NGC 6760, PSR J1911+0101B, an isolated object with a rotational period of 5.38 ms and a dispersion measure DM = 196.7 cm-3 pc. Both pulsars are located within 1.3 core radii of the cluster center and have negative period derivatives. The resulting lower limits for the accelerations of the pulsars are within the range expected given a simple model of the cluster. A search for eclipses in the PSR J1911+0102A binary system using both telescopes yielded negative results. The corresponding limits on the extra gas column density at superior conjunction are consistent with the hypothesis that the observational properties of ultra-low-mass binary pulsars like PSR J1911+0102A are strongly affected by the inclination of the orbita...

  17. Search for Optical Pulsations in PSR J0337+1715

    CERN Document Server

    Strader, M J; Meeker, S R; Szypryt, P; Walter, A B; van Eyken, J C; Ulbricht, G; Stoughton, C; Bumble, B; Kaplan, D L; Mazin, B A

    2016-01-01

    We report on a search for optical pulsations from PSR J0337+1715 at its observed radio pulse period. PSR J0337+1715 is a millisecond pulsar (2.7 ms spin period) in a triple hierarchical system with two white dwarfs, and has a known optical counterpart with g-band magnitude 18. The observations were done with the Array Camera for Optical to Near-IR Spectrophotometry (ARCONS) at the 200" Hale telescope at Palomar Observatory. No significant pulsations were found in the range 4000-11000 angstroms, and we can limit pulsed emission in g-band to be fainter than 25 mag.

  18. SAS-2 gamma-ray observations of PSR 1747-46

    Science.gov (United States)

    Thompson, D. J.; Fichtel, C. E.; Kniffen, D. A.; Lamb, R. C.; Oegelman, H. B.

    1976-01-01

    Observations with the SAS-2 high energy ( 35 MeV) gamma-ray telescope show evidence of gamma-ray emission from the radio pulsar PSR 1747-46. When the arrival times of gamma-rays from the region of the pulsar were converted to pulsar phases using the radio period and period derivative, a single peak was found in the phase plot, with a Poisson probability of occurring by chance of .00008. Independently, the time-averaged data for the PSR 1747-46 region show an enhancement over the surrounding region of the sky at the same galactic latitude, with a Poisson probability of chance occurrence of less than .008. The probability that these results are chance is the product of these two probabilities times the number of radio pulsars examined (73). This overall probability is sufficiently small (.00005) to suggest an identification of a new gamma-ray pulsar. In the gamma-ray pulsar plot, the peak falls 0.16 + or - 0.03 period after the radio pulsar peak. This phase shift is, within uncertainties, the same as that observed between the single radio peak and the first of the two gamma-ray peaks seen in the phase plot for PSR-0833-45 (the Vela pulsar).

  19. Detection of Hidden Pulsar J0737-3039B

    Science.gov (United States)

    Maynard, Tessa

    2016-01-01

    The double pulsar system, PSR J0737-3039, contains companions PSR J0737-3039A & PSR J0737-3039B, which rotate at 23 ms and 2.8 respectively. As of March 2008 pulsar B's radio signal disappeared, with previous decreases in flux density by 0.177 mJy yr-1 and evolving pulse profile seperation of 2fdg6 yr-1 from a single peak to a double peak. Models using the system's relativistic spin precession have predicted the reappearance of PSR J0737-3039B in approximately 2014 or 2035. Using data from the Green Bank telescope we attempt to redetect pulsar B and explain the mechanics of its disappearance.

  20. EINSTEIN-HOME DISCOVERY OF 24 PULSARS IN THE PARKES MULTI-BEAM PULSAR SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Knispel, B.; Kim, H.; Allen, B.; Aulbert, C.; Bock, O.; Eggenstein, H.-B.; Fehrmann, H.; Machenschalk, B. [Albert-Einstein-Institut, Max-Planck-Institut fuer Gravitationsphysik, D-30167 Hannover (Germany); Eatough, R. P.; Keane, E. F.; Kramer, M. [Max-Planck-Institut fuer Radioastronomie, D-53121 Bonn (Germany); Anderson, D. [University of California at Berkeley, Berkeley, CA 94720 (United States); Crawford, F.; Rastawicki, D. [Department of Physics and Astronomy, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604 (United States); Hammer, D.; Papa, M. A.; Siemens, X. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Lyne, A. G. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Miller, R. B. [Department of Physics, West Virginia University, 111 White Hall, Morgantown, WV 26506 (United States); Sarkissian, J., E-mail: benjamin.knispel@aei.mpg.de [CSIRO Parkes Observatory, Parkes, NSW 2870 (Australia); and others

    2013-09-10

    We have conducted a new search for radio pulsars in compact binary systems in the Parkes multi-beam pulsar survey (PMPS) data, employing novel methods to remove the Doppler modulation from binary motion. This has yielded unparalleled sensitivity to pulsars in compact binaries. The required computation time of Almost-Equal-To 17, 000 CPU core years was provided by the distributed volunteer computing project Einstein-Home, which has a sustained computing power of about 1 PFlop s{sup -1}. We discovered 24 new pulsars in our search, 18 of which were isolated pulsars, and 6 were members of binary systems. Despite the wide filterbank channels and relatively slow sampling time of the PMPS data, we found pulsars with very large ratios of dispersion measure (DM) to spin period. Among those is PSR J1748-3009, the millisecond pulsar with the highest known DM ( Almost-Equal-To 420 pc cm{sup -3}). We also discovered PSR J1840-0643, which is in a binary system with an orbital period of 937 days, the fourth largest known. The new pulsar J1750-2536 likely belongs to the rare class of intermediate-mass binary pulsars. Three of the isolated pulsars show long-term nulling or intermittency in their emission, further increasing this growing family. Our discoveries demonstrate the value of distributed volunteer computing for data-driven astronomy and the importance of applying new analysis methods to extensively searched data.

  1. Einstein@Home Discovery of 24 Pulsars in the Parkes Multi-beam Pulsar Survey

    Science.gov (United States)

    Knispel, B.; Eatough, R. P.; Kim, H.; Keane, E. F.; Allen, B.; Anderson, D.; Aulbert, C.; Bock, O.; Crawford, F.; Eggenstein, H.-B.; Fehrmann, H.; Hammer, D.; Kramer, M.; Lyne, A. G.; Machenschalk, B.; Miller, R. B.; Papa, M. A.; Rastawicki, D.; Sarkissian, J.; Siemens, X.; Stappers, B. W.

    2013-09-01

    We have conducted a new search for radio pulsars in compact binary systems in the Parkes multi-beam pulsar survey (PMPS) data, employing novel methods to remove the Doppler modulation from binary motion. This has yielded unparalleled sensitivity to pulsars in compact binaries. The required computation time of ≈17, 000 CPU core years was provided by the distributed volunteer computing project Einstein@Home, which has a sustained computing power of about 1 PFlop s-1. We discovered 24 new pulsars in our search, 18 of which were isolated pulsars, and 6 were members of binary systems. Despite the wide filterbank channels and relatively slow sampling time of the PMPS data, we found pulsars with very large ratios of dispersion measure (DM) to spin period. Among those is PSR J1748-3009, the millisecond pulsar with the highest known DM (≈420 pc cm-3). We also discovered PSR J1840-0643, which is in a binary system with an orbital period of 937 days, the fourth largest known. The new pulsar J1750-2536 likely belongs to the rare class of intermediate-mass binary pulsars. Three of the isolated pulsars show long-term nulling or intermittency in their emission, further increasing this growing family. Our discoveries demonstrate the value of distributed volunteer computing for data-driven astronomy and the importance of applying new analysis methods to extensively searched data.

  2. The near-infrared detection of PSR B0540-69 and its nebula

    CERN Document Server

    MignanI, R P; Hummel, W; Zajczyk, A; Rudak, B; Kanbach, G; Slowikowska, A

    2012-01-01

    The ~1700 year old PSR B0540-69 in the LMC is considered the twin of the Crab pulsar because of its similar spin parameters, magnetic field, and energetics. Its optical spectrum is fit by a power-law, ascribed to synchrotron radiation, like for the young Crab and Vela pulsars. nIR observations, never performed for PSR B0540-69, are crucial to determine whether the optical power-law spectrum extends to longer wavelengths or a new break occurs, like it happens for both the Crab and Vela pulsars in the mIR, hinting at an even more complex particle energy and density distribution in the pulsar magnetosphere. We observed PSR B0540-69 in the J, H, and Ks bands with the VLT to detect it, for the first time, in the nIR and characterise its optical-to-nIR spectrum. To disentangle the pulsar emission from that of its pulsar wind nebula (PWN), we obtained high-spatial resolution adaptive optics images with NACO. We could clearly identify PSR B0540-69 in our J, H, and Ks-band images and measure its flux (J=20.14, H=19.33...

  3. Discovery of Two New Pulsars in Archival Data

    CERN Document Server

    Mickaliger, Mitchell B; Boyles, Jason; McLaughlin, Maura A; Collins, Adam; Hough, Logan; Tehrani, Nathan; Tenney, Craig

    2012-01-01

    Reprocessing of the Parkes Multibeam Pulsar Survey has resulted in the discovery of two previously unknown pulsars and several as-yet-unconfirmed candidates. One of the new pulsars, PSR J1725-3853, is an isolated 4.79-ms pulsar with a DM of 158.2 pc cm^-3. The other, PSR J1227-6208, has a period of 34.53 ms, a DM of 362.6 pc cm^-3, is in a 6.7 day binary orbit, and was independently detected in an ongoing high-resolution Parkes survey by Thornton et al. and also in independent processing by Einstein@Home volunteers. These pulsars were likley missed in earlier processing efforts due to their high DMs and short periods. These serendipitous discoveries suggest that further pulsars are awaiting discovery in the multibeam survey data.

  4. Fermi-LAT TOO observations of PSR J1119-6127 following its 2016 magnetar-like outburst

    Science.gov (United States)

    Younes, G.; Archibald, R.; Kouveliotou, C.; Kaspi, V.; Ray, P. S.; McEnery, J.; Fermi LAT Collaboration

    2016-08-01

    We requested and obtained Fermi-LAT target of opportunity (TOO) observations of the high-B gamma-ray pulsar PSR J1119-6127 between 2016 August 1 - 8. This pulsar recently showed magnetar-like bursts on 2016 July 27 and 28 (GCNs #19735, #19736, and ATel #9274).

  5. The Fastest Rotating Pulsar: a Strange Star?

    Institute of Scientific and Technical Information of China (English)

    徐仁新; 徐轩彬; 吴鑫基

    2001-01-01

    According to the observational limits on the radius and mass, the fastest rotating pulsar (PSR 1937+21) is probably a strange star, or at least some neutron star equations of state should be ruled out, if we suggest that a dipole magnetic field is relevant to its radio emission. We presume that the millisecond pulsar is a strange star with much low mass, small radius and weak magnetic moment.

  6. Testing Lorentz violation with binary pulsars: constraints on standard model extension

    Institute of Scientific and Technical Information of China (English)

    Yi Xie

    2013-01-01

    Under the standard model extension (SME) framework,Lorentz invariance is tested in five binary pulsars:PSR J0737-3039,PSR B 1534+ 12,PSR J 1756-2251,PSR B1913+16 and PSR B2127+11C.By analyzing the advance of periastron,we obtain the constraints on a dimensionless combination of SME parameters that is sensitive to timing observations.The results imply no evidence for the break of Lorentz invariance at the 10-10 level,one order of magnitude larger than the previous estimation.

  7. VLT polarimetry observations of PSR B0656+14

    CERN Document Server

    Mignani, R P; Shearer, A; Testa, V; Sowikowska, A; Rudak, B; Krzeszowki, K; Kanbach, G

    2015-01-01

    Optical polarisation measurements are key tests for different models of the pulsar magnetosphere. Furthermore, comparing the relative orientation of the phase-averaged linear polarisation direction and the pulsar proper motion vector may unveil a peculiar alignment, clearly seen in the Crab pulsar. Our goal is to obtain the first measurement of the phase-averaged optical linear polarisation of the fifth brightest optical pulsar, PSR\\, B0656+14, which has also a precisely measured proper motion, and verify a possible alignment between the polarisation direction and the proper motion vector. We carried out observations with the Very Large Telescope (VLT) to measure the phase-averaged optical polarisation degree (P.D.) and position angle (P.A.) of PSR B0656+14. We measured a P.D. of $11.9\\%\\pm5.5\\%$ and a P.A. of $125.8\\degr\\pm13.2\\degr$, measured East of North. Albeit of marginal significance, this is the first measurement of the phase-averaged optical P. D. for this pulsar. Moreover, we found that the P.A. of ...

  8. Discovery of Two High-Magnetic-Field Radio Pulsars

    CERN Document Server

    Camilo, F M; Lyne, A G; Manchester, R N; Bell, J F; D'Amico, N; McKay, N P F; Crawford, F

    2000-01-01

    We report the discovery of two young isolated radio pulsars with very high inferred magnetic fields. PSR J1119-6127 has period P = 0.407 s, and the largest period derivative known among radio pulsars, Pdot = 4.0e-12. Under standard assumptions these parameters imply a characteristic spin-down age of only tau = 1.6 kyr and a surface dipole magnetic field strength of B = 4.1e13 G. We have measured a stationary period-second-derivative for this pulsar, resulting in a braking index of n = 2.91+-0.05. We have also observed a glitch in the rotation of the pulsar, with fractional period change Delta_P/P = -4.4e-9. Archival radio imaging data suggest the presence of a previously uncataloged supernova remnant centered on the pulsar. The second pulsar, PSR J1814-1744, has P = 3.975 s and Pdot = 7.4e-13. These parameters imply tau = 85 kyr, and B = 5.5e13 G, the largest of any known radio pulsar. Both PSR J1119-6127 and PSR J1814-1744 show apparently normal radio emission in a regime of magnetic field strength where som...

  9. Eccentric Binary Millisecond Pulsars

    CERN Document Server

    Freire, Paulo C C

    2009-01-01

    In this paper we review the recent discovery of several millisecond pulsars (MSPs) in eccentric binary systems. Timing these MSPs we were able to estimate (and in one case precisely measure) their masses. These results suggest that, as a class, MSPs have a much wider range of masses (1.3 to > 2 solar masses) than the normal and mildly recycled pulsars found in double neutron star (DNS) systems (1.25 < Mp < 1.44 solar masses). This is very likely to be due to the prolonged accretion episode that is thought to be required to form a MSP. The likely existence of massive MSPs makes them a powerful probe for understanding the behavior of matter at densities larger than that of the atomic nucleus; in particular, the precise measurement of the mass of PSR J1903+0327 ($1.67 +/- 0.01 solar masses) excludes several "soft" equations of state for dense matter.

  10. Chandra Observations of Outflows from PSR J1509-5850

    CERN Document Server

    Klingler, Noel; Rangelov, Blagoy; Pavlov, George G; Posselt, Bettina; Ng, C -Y

    2016-01-01

    PSR J1509-5850 is a middle-aged pulsar with the period P ~ 89 ms, spin-down power Edot = 5.1 x 10^35 erg/s, at a distance of about 3.8 kpc. We report on deep Chandra X-ray Observatory observations of this pulsar and its pulsar wind nebula (PWN). In addition to the previously detected tail extending up to 7' southwest from the pulsar (the southern outflow), the deep images reveal a similarly long, faint diffuse emission stretched toward the north (the northern outflow) and the fine structure of the compact nebula (CN) in the pulsar vicinity. The CN is resolved into two lateral tails and one axial tail pointing southwest (a morphology remarkably similar to that of the Geminga PWN), which supports the assumption that the pulsar moves towards the northeast. The luminosities of the southern and northern outflows are about 1 x 10^33 and 4 x 10^32 erg/s, respectively. The spectra extracted from four regions of the southern outflow do not show any softening with increasing distance from the pulsar. The lack of synchr...

  11. 1974: the discovery of the first binary pulsar

    CERN Document Server

    Damour, Thibault

    2014-01-01

    The 1974 discovery, by Russell A. Hulse and Joseph H. Taylor, of the first binary pulsar PSR 1913+16, opened up new possibilities for the study of relativistic gravity. PSR 1913+16, as well as several other binary pulsars, provided {\\it direct} observational proofs that gravity propagates at the velocity of light and has a quadrupolar structure. Binary pulsars also provided accurate tests of the strong-field regime of relativistic gravity. General Relativity has passed all the binary pulsar tests with flying colors. The discovery of binary pulsars had also very important consequences for astrophysics: accurate measurement of neutron star masses, improved understanding of the possible evolution scenarios for the co-evolution of binary stars, proof of the existence of binary neutron stars emitting gravitational waves for hundreds of millions of years, before coalescing in catastrophic events probably leading to an important emission of electromagnetic radiation and neutrinos. This article reviews the history of...

  12. Einstein@Home Discovery of 24 Pulsars in the Parkes Multi-beam Pulsar Survey

    CERN Document Server

    Knispel, B; Kim, H; Keane, E F; Allen, B; Anderson, D; Aulbert, C; Bock, O; Crawford, F; Eggenstein, H -B; Fehrmann, H; Hammer, D; Kramer, M; Lyne, A G; Machenschalk, B; Miller, R B; Papa, M A; Rastawicki, D; Sarkissian, J; Siemens, X; Stappers, B W

    2013-01-01

    We have conducted a new search for radio pulsars in compact binary systems in the Parkes multi-beam pulsar survey (PMPS) data, employing novel methods to remove the Doppler modulation from binary motion. This has yielded unparalleled sensitivity to pulsars in compact binaries. The required computation time of approximately 17 000 CPU core years was provided by the distributed volunteer computing project Einstein@Home, which has a sustained computing power of about one PFlop/s. We discovered 24 new pulsars in our search, of which 18 were isolated pulsars, and six were members of binary systems. Despite the wide filterbank channels and relatively slow sampling time of the PMPS data, we found pulsars with very large ratios of dispersion measure (DM) to spin period. Among those is PSR J1748-3009, the millisecond pulsar with the highest known DM (420 pc cm^{-3}). We also discovered PSR J1840-0643, which is in a binary system with an orbital period of 937 days, the fourth largest known. The new pulsar J1750-2531 li...

  13. Searching for the optical counterparts of two young gamma-ray pulsars

    CERN Document Server

    Mignani, R P; Marelli, M; De Luca, A; Pierbattista, M; Razzano, M; Salvetti, D; Belfiore, A; Shearer, A; Moran, P

    2016-01-01

    We report on the first deep optical observations of two $\\gamma$-ray pulsars, both among the very first discovered by the {\\em Fermi} Gamma-ray Space Telescope. The two pulsars are the radio-loud PSR\\, J1907+0602 in the TeV pulsar wind nebula (PWN) MGRO\\, J1908+06 and the radio-quiet PSR\\, J1809$-$2332 in the "Taz" radio/X-ray PWN. They are relatively young, with spin-down ages of 19.5 and 67.6 kyr, respectively and energetic, with spin-down energies $\\dot{E}_{\\rm rot} = 2.8 \\times 10^{36}$ erg s$^{-1}$ (PSR\\, J1907+0602) and $\\dot{E}_{\\rm rot} = 4.3 \\times 10^{35}$ erg s$^{-1}$ (PSR\\, J1809$-$2332). Both pulsars have been detected in the X-rays by \\xmm, which makes them viable targets for optical observations. We observed the pulsar fields in the B and V bands with the Very Large Telescope (VLT) in June/July 2015. Neither of the two pulsars has been detected down to $3\\sigma$ limiting magnitudes of $m_{\\rm v} \\sim 26.9$ and $m_{\\rm v} \\sim 27.6$ for PSR\\, J1907+0602 and PSR\\, J1809$-$2332, respectively. We d...

  14. Improving Pulsar Distances by Modelling Interstellar Scattering

    CERN Document Server

    Deshpande, A A

    1998-01-01

    We present here a method to study the distribution of electron density fluctuations in pulsar directions as well as to estimate pulsar distances. The method, based on a simple two-component model of the scattering medium discussed by Gwinn et al. (1993), uses scintillation & proper motion data in addition to the measurements of angular broadening & temporal broadening to solve for the model parameters, namely, the fractional distance to a discrete scatterer and the ascociated relative scattering strength. We show how this method can be used to estimate pulsar distances reliably, when the location of a discrete scatterer (e.g. an HII region), if any, is known. Considering the specific example of PSR B0736-40, we illustrate how a simple characterization of the Gum nebula region (using the data on the Vela pulsar) is possible and can be used along with the temporal broadening measurements to estimate pulsar distances.

  15. On the PSR B1133+16 optical counterpart

    CERN Document Server

    Zharikov, Sergey

    2013-01-01

    The aim of this work is confirming the optical identification of PSR B1133+16, whose candidate optical counterpart was detected in Very Large Telescope (VLT) images obtained back in 2003. We used new deep optical images of the PSR B1133+16 field obtained with both the 10.4 m Gran Telescopio Canarias (GTC) and the VLT in the g' and B bands, respectively, to confirm the detection of its candidate optical counterpart and its coincidence with the most recent pulsar's radio coordinates. We did not detect any object at the position of the pulsar candidate counterpart (B~28), measured in our 2003 VLT images. However, we tentatively detected an object of comparable brightness in both the 2012 GTC and VLT images, whose position is offset by ~3.03" from that of the pulsar's candidate counterpart in the 2003 VLT images and lies along the pulsar's proper motion direction. Accounting for the time span of ~9 years between the 2012 quasi-contemporary GTC and VLT images and the 2003 VLT one, this offset is consistent with th...

  16. Discovery of millisecond pulsars in radio searches of southern Fermi LAT sources

    CERN Document Server

    Keith, M J; Ray, P S; Ferrara, E C; Parkinson, P M Saz; Celik, O; Belfiore, A; Donato, D; Cheung, C C; Abdo, A A; Camilo, F; Freire, P C C; Guillemot, L; Harding, A K; Kramer, M; Michelson, P F; Ransom, S M; Romani, R W; Smith, D A; Thompson, D J; Weltevrede, P; Wood, K S

    2011-01-01

    Using the Parkes radio telescope we have carried out deep observations of eleven unassociated gamma-ray sources. Periodicity searches of these data have discovered two millisecond pulsars, PSR J1103-5403 (1FGL J1103.9-5355) and PSR J2241-5236 (1FGL J2241.9-5236), and a long period pulsar, PSR J1604-44 (1FGL J1604.7-4443). In addition we searched for but did not detect any radio pulsations from six gammaray pulsars discovered by the Fermi satellite to a level of - 0.04 mJy (for pulsars with a 10% duty cycle). Timing of the millisecond pulsar PSR J1103-5403 has shown that its position is 9' from the centroid of the gamma-ray source. Since these observations were carried out, independent evidence has shown that 1FGL J1103.9-5355 is associated with the flat spectrum radio source PKS 1101-536. It appears certain that the pulsar is not associated with the gamma-ray source, despite the seemingly low probability of a chance detection of a radio millisecond pulsar. We consider that PSR J1604-44 is a chance discovery o...

  17. LOFAR discovery of a quiet emission mode in PSR B0823+26

    CERN Document Server

    Sobey, C; Hessels, J W T; Weltevrede, P; Noutsos, A; Stappers, B W; Kramer, M; Bassa, C; Lyne, A G; Kondratiev, V I; Hassall, T E; Keane, E F; Bilous, A V; Breton, R P; Grießmeier, J -M; Karastergiou, A; Pilia, M; Serylak, M; ter Veen, S; van Leeuwen, J; Alexov, A; Anderson, J; Asgekar, A; Avruch, I M; Bell, M E; Bentum, M J; Bernardi, G; Best, P; Bîrzan, L; Bonafede, A; Breitling, F; Broderick, J; Brüggen, M; Corstanje, A; Carbone, D; de Geus, E; de Vos, M; van Duin, A; Duscha, S; Eislöffel, J; Falcke, H; Fallows, R A; Fender, R; Ferrari, C; Frieswijk, W; Garrett, M A; Gunst, A W; Hamaker, J P; Heald, G; Hoeft, M; Hörandel, J; Jütte, E; Kuper, G; Maat, P; Mann, G; Markoff, S; McFadden, R; McKay-Bukowski, D; McKean, J P; Mulcahy, D D; Munk, H; Nelles, A; Norden, M J; Orrù, E; Paas, H; Pandey-Pommier, M; Pandey, V N; Pietka, G; Pizzo, R; Polatidis, A G; Rafferty, D; Renting, A; Röttgering, H; Rowlinson, A; Scaife, A M M; Schwarz, D; Sluman, J; Smirnov, O; Steinmetz, M; Stewart, A; Swinbank, J; Tagger, M; Tang, Y; Tasse, C; Thoudam, S; Toribio, C; Vermeulen, R; Vocks, C; van Weeren, R J; Wijers, R A M J; Wise, M W; Wucknitz, O; Yatawatta, S; Zarka, P

    2015-01-01

    PSR B0823+26, a 0.53-s radio pulsar, displays a host of emission phenomena over timescales of seconds to (at least) hours, including nulling, subpulse drifting, and mode-changing. Studying pulsars like PSR B0823+26 provides further insight into the relationship between these various emission phenomena and what they might teach us about pulsar magnetospheres. Here we report on the LOFAR discovery that PSR B0823+26 has a weak and sporadically emitting 'quiet' (Q) emission mode that is over 100 times weaker (on average) and has a nulling fraction forty-times greater than that of the more regularly-emitting 'bright' (B) mode. Previously, the pulsar has been undetected in the Q-mode, and was assumed to be nulling continuously. PSR B0823+26 shows a further decrease in average flux just before the transition into the B-mode, and perhaps truly turns off completely at these times. Furthermore, simultaneous observations taken with the LOFAR, Westerbork, Lovell, and Effelsberg telescopes between 110 MHz and 2.7 GHz demo...

  18. On the association of G343.1-2.3 and PSR 1706-44

    CERN Document Server

    Dodson, R; Osborne, J; Udaya-Shankar, N; Rao, A P

    2001-01-01

    The observations of the supernova remnant G343.1-2.3 with the Mauritius Radio Telescope, the Australia Compact Array, and the Hobart Single dish are presented. With these more sensitive measurements the association with the pulsar PSR1706-44 becomes much more likely. The major points from the observations are presented.

  19. Glitch observation and hard X-ray power law measurement in PSR J1119-6127

    Science.gov (United States)

    Archibald, R. F.; Tendulkar, S. P.; Scholz, P. A.; Kaspi, V. M.

    2016-07-01

    We report on Swift-XRT, NuSTAR and Fermi spectral and timing observations of PSR J1119-6127, a rotation-powered high magnetic field pulsar that showed a magnetar-like burst on 2016 July 28, 01:27:51 UT (ATel #9274, ATel #9282).

  20. Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

    Energy Technology Data Exchange (ETDEWEB)

    B. Allen et al.

    2003-12-11

    The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times 10{sup -22}.

  1. Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

    CERN Document Server

    Allen, B; Abbott, B; Abbott, R; Adhikari, R; Allen, B; Amin, R; Anderson, S B; Anderson, W G; Araya, M; Armandula, H; Asiri, F; Aufmuth, P; Aulbert, C; Babak, S V; Balasubramanian, R; Ballmer, S; Barish, B C; Barker, D; Barker-Patton, C; Barnes, M; Barr, B; Barton, M A; Bayer, K; Beausoleil, R; Belczynski, K; Bennett, R; Berukoff, S J; Betzwieser, J; Bhawal, B; Billingsley, G; Black, E; Blackburn, K; Bland-Weaver, B; Bochner, B; Bogue, L; Bork, R G; Bose, S; Brady, P R; Brau, J E; Brown, D A; Brozek, S; Bullington, A; Buonanno, A; Burgess, R; Busby, D; Butler, W E; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cantley, C A; Cardenas, L; Carter, K; Casey, M M; Castiglione, J; Chandler, A; Chapsky, J; Charlton, P; Chatterji, S; Chen, Y; Chickarmane, V; Chin, D; Christensen, N; Churches, D; Colacino, C N; Coldwell, R; Coles, M; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Creighton, T D; Crooks, D R M; Csatorday, P; Cusack, B J; Cutler, C; D'Ambrosio, E; Danzmann, K; Davies, R; Daw, E; De Bra, D; Delker, T; DeSalvo, R; Dhurandhar, S V; Ding, H; Drever, R W P; Dupuis, R J; Ebeling, C; Edlund, J; Ehrens, P; Elliffe, E J; Etzel, T; Evans, M; Evans, T; Fallnich, C; Farnham, D; Fejer, M M; Fine, M; Finn, L S; Flanagan, E; Freise, A; Frey, R; Fritschel, P; Frolov, V; Fyffe, M; Ganezer, K S; Giaime, J A; Gillespie, A; Goda, K; González, G; Gossler, S; Grandclément, P; Grant, A; Gray, C; Gretarsson, A M; Grimmett, D; Grote, H; Grünewald, S; Günther, M; Gustafson, E; Gustafson, R; Hamilton, W O; Hammond, M; Hanson, J; Hardham, C; Harry, G; Hartunian, A; Heefner, J; Hefetz, Y; Heinzel, G; Heng, I S; Hennessy, M; Hepler, N; Heptonstall, A; Heurs, M; Hewitson, M; Hindman, N; Hoang, P; Hough, J; Hrynevych, M; Hua, W; Ingley, R; Ito, M; Itoh, Y; Ivanov, A; Jennrich, O; Johnson, W W; Johnston, W; Jones, L; Jungwirth, D; Kalogera, V; Katsavounidis, E; Kawabe, K; Kawamura, S; Kells, W; Kern, J; Khan, A; Killbourn, S; Killow, C J; Kim, C; King, C; King, P; Klimenko, S; Kloevekorn, P; Koranda, S; Kotter, K; Kovalik, Yu; Kozak, D; Krishnan, B; Landry, M; Langdale, J; Lantz, B; Lawrence, R; Lazzarini, A; Lei, M; Leonhardt, V; Leonor, I; Libbrecht, K; Lindquist, P; Liu, S; Logan, J; Lormand, M; Lubinski, M; Lück, H B; Lyons, T T; Machenschalk, B; MacInnis, M; Mageswaran, M; Mailand, K; Majid, W; Malec, M; Mann, F; Marin, A; Marka, S; Maros, E; Mason, J; Mason, K; Matherny, O; Matone, L; Mavalvala, N; McCarthy, R; McClelland, D E; McHugh, M; McNamara, P; Mendell, G; Meshkov, S; Messenger, C; Mitselmakher, G; Mittleman, R; Miyakawa, O; Miyoki, S; Mohanty, S; Moreno, G; Mossavi, K; Mours, B; Müller, G; Mukherjee, S; Myers, J; Nagano, S; Nash, T; Naundorf, H; Nayak, R; Newton, G; Nocera, F; Nutzman, P; Olson, T; O'Reilly, B; Ottaway, D J; Ottewill, A; Ouimette, D A; Overmier, H; Owen, B J; Papa, M A; Parameswariah, C; Parameshwaraiah, V; Pedraza, M; Penn, S; Pitkin, M; Plissi, M; Pratt, M; Quetschke, V; Raab, F; Radkins, H; Rahkola, R; Rakhmanov, M; Rao, S R; Redding, D; Regehr, M W; Regimbau, T; Reilly, K T; Reithmaier, K; Reitze, D H; Richman, S; Riesen, R; Riles, K; Rizzi, A; Robertson, D I; Robertson, N A; Robison, L; Roddy, S; Rollins, J; Romano, J D; Romie, J; Rong, H; Rose, D; Rotthoff, E; Rowan, S; Rüdiger, A; Russell, P; Ryan, K; Salzman, I; Sanders, G H; Sannibale, V; Sathyaprakash, B; Saulson, P R; Savage, R; Sazonov, A; Schilling, R; Schlaufman, K; Schmidt, V; Schofield, R; Schrempel, M; Schutz, B F; Schwinberg, P; Scott, S M; Searle, A C; Sears, B; Seel, S; Sengupta, A S; Shapiro, C A; Shawhan, P S; Shoemaker, D H; Shu, Q Z; Sibley, A; Siemens, X; Sievers, L; Sigg, D; Sintes, A M; Skeldon, K D; Smith, J R; Smith, M; Smith, M R; Sneddon, P; Spero, R; Stapfer, G; Strain, K A; Strom, D; Stuver, A; Summerscales, T; Sumner, M C; Sutton, P J; Sylvestre, J; Takamori, A; Tanner, D B; Tariq, H; Taylor, I; Taylor, R; Thorne, K S; Tibbits, M; Tilav, S; Tinto, M; Torres, C; Torrie, C; Traeger, S; Traylor, G; Tyler, W; Ugolini, D W; Vallisneri, M; Van Putten, M H P M; Vass, S; Vecchio, A; Vorvick, C; Wallace, L; Walther, H; Ward, H; Ware, B; Watts, K; Webber, D; Weidner, A; Weiland, U; Weinstein, A; Weiss, R; Welling, H; Wen, L; Wen, S; Whelan, J T; Whitcomb, S E; Whiting, B F; Willems, P A; Williams, P R; Williams, R; Willke, B; Wilson, A; Winjum, B J; Winkler, W; Wise, S; Wiseman, A G; Wooley, R; Worden, J; Yakushin, I; Yamamoto, H; Yoshida, S; Zawischa, I; Zhang, L; Zotov, N P; Zucker, M; Zweizig, J

    2004-01-01

    The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times $10^{-22}$.

  2. Observing peculiar γ-ray pulsars with AGILE

    Science.gov (United States)

    Pilia, M.; Pellizzoni, A.

    2011-08-01

    The AGILE γ-ray satellite provides large sky exposure levels (>=109 cm2 s per year on the Galactic Plane) with sensitivity peaking at E ~100 MeV where the bulk of pulsar energy output is typically released. Its ~1 μs absolute time tagging capability makes it perfectly suited for the study of γ-ray pulsars. AGILE collected a large number of γ-ray photons from EGRET pulsars (>=40,000 pulsed counts for Vela) in two years of observations unveiling new interesting features at sub-millisecond level in the pulsars' high-energy light-curves, γ-ray emission from pulsar glitches and Pulsar Wind Nebulae. AGILE detected about 20 nearby and energetic pulsars with good confidence through timing and/or spatial analysis. Among the newcomers we find pulsars with very high rotational energy losses, such as the remarkable PSR B1509-58 with a magnetic field in excess of 1013 Gauss, and PSR J2229+6114 providing a reliable identification for the previously unidentified EGRET source 3EG2227+6122. Moreover, the powerful millisecond pulsar B1821-24, in the globular cluster M28, is detected during a fraction of the observations.

  3. The Green Bank Telescope 350 MHz Drift-scan Survey I: Survey Observations and the Discovery of 13 Pulsars

    CERN Document Server

    Boyles, Jason; Ransom, Scott M; Stairs, Ingrid H; Lorimer, Duncan R; McLaughlin, Maura A; Hessels, Jason W T; Kaspi, Vicky M; Kondratiev, Vlad I; Archibald, Anne; Berndsen, Aaron; Cardoso, Rogerio F; Cherry, Angus; McPhee, Christie A; Pennucci, Tim; Roberts, Mallory S E; Stovall, Kevin; van Leeuwen, Joeri

    2012-01-01

    Over the summer of 2007, we obtained 1191 hours of `drift-scan' pulsar search observations with the Green Bank Telescope at a radio frequency of 350 MHz. Here we describe the survey setup, search procedure, and the discovery and follow-up timing of thirteen pulsars. Among the new discoveries, one (PSR J1623-0841) was discovered only through its single pulses, two (PSRs J1327-0755 and J1737-0814) are millisecond pulsars, and another (PSR J2222-0137) is a mildly recycled pulsar. PSR J1327-0755 is a 2.7 ms pulsar at a DM of 27.9 pc cm^{-3} in a 8.7 day orbit with a minimum companion mass of 0.22$ solar mass. PSR J1737-0814 is a 4.2 ms pulsar at a DM of 55.3 pc cm^{-3} in a 79.3 day orbit with a minimum companion mass of 0.06 solar mass. PSR J2222$-$0137 is a 32.8 ms pulsar at a very low DM of 3.27 pc cm^{-3} in a 2.4 day orbit with a minimum companion mass of 1.11 solar mass. It is most likely a white dwarf-neutron star system or an unusual low-eccentricity double neutron star system. Ten other pulsars discovere...

  4. Realistic modeling of the pulse profile of PSR J0737-3039A

    Energy Technology Data Exchange (ETDEWEB)

    Perera, B. B. P.; Kim, C.; McLaughlin, M. A. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Ferdman, R. D. [Department of Physics, McGill University, Ernest Rutherford Physics Building, 3600 University Street, Montreal, QC H3A 2T8 (Canada); Kramer, M.; Freire, P. C. C. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1 (Canada); Possenti, A. [INAF-Osservatorio Astronomica di Cagliari, Loc. Poggio dei Pini, Strada 54, I-09012 Capoterra (Italy)

    2014-05-20

    The Double Pulsar, PSR J0737-3039A/B, is a unique system in which both neutron stars have been detected as radio pulsars. As shown in Ferdman et al., there is no evidence for pulse profile evolution of the A pulsar, and the geometry of the pulsar was fit well with a double-pole circular radio beam model. Assuming a more realistic polar cap model with a vacuum retarded dipole magnetosphere configuration including special relativistic effects, we create synthesized pulse profiles for A given the best-fit geometry from the simple circular beam model. By fitting synthesized pulse profiles to those observed from pulsar A, we constrain the geometry of the radio beam, namely the half-opening angle and the emission altitude, to be ∼30° and ∼10 neutron star radii, respectively. Combining the observational constraints of PSR J0737-3039A/B, we are able to construct the full three-dimensional orbital geometry of the Double Pulsar. The relative angle between the spin axes of the two pulsars (Δ{sub S}) is estimated to be ∼(138° ± 5°) at the current epoch and will likely remain constant until tidal interactions become important in ∼85 Myr, at merger.

  5. Realistic Modeling of the Pulse Profile of PSR J$0737$$-$$3039$A

    CERN Document Server

    Perera, B B P; McLaughlin, M A; Ferdman, R D; Kramer, M; Stairs, I H; Freire, P C C; Possenti, A

    2014-01-01

    The Double Pulsar, PSR J$0737$$-$$3039$A/B, is a unique system in which both neutron stars have been detected as radio pulsars. As shown in Ferdman et al., there is no evidence for pulse profile evolution of the A pulsar, and the geometry of the pulsar was fit well with a double-pole circular radio beam model. Assuming a more realistic polar cap model with a vacuum retarded dipole magnetosphere configuration including special relativistic effects, we create synthesized pulse profiles for A given the best-fit geometry from the simple circular beam model. By fitting synthesized pulse profiles to those observed from pulsar A, we constrain the geometry of the radio beam, namely the half-opening angle and the emission altitude, to be $30^\\circ$ and $10$ neutron star radii, respectively. Combining the observational constraints of PSR J$0737$$-$$3039$A/B, we are able to construct the full three-dimensional orbital geometry of the Double Pulsar. The relative angle between the spin axes of the two pulsars ($\\Delta_S$)...

  6. Time-domain and spectral properties of pulsars at 154 MHz

    CERN Document Server

    Bell, M E; Johnston, S; Kaplan, D L; Croft, S; Hancock, P; Callingham, J R; Zic, A; Dobie, D; Swiggum, J K; Rowlinson, A; Hurley-Walker, N; Offringa, A R; Bernardi, G; Bowman, J D; Briggs, F; Cappallo, R J; Deshpande, A A; Gaensler, B M; Greenhill, L J; Hazelton, B J; Johnston-Hollitt, M; Lonsdale, C J; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Ord, S M; Prabu, T; Shankar, N Udaya; Srivani, K S; Subrahmanyan, R; Tingay, S J; Wayth, R B; Webster, R L; Williams, A; Williams, C L

    2016-01-01

    We present 154 MHz Murchison Widefield Array imaging observations and variability information for a sample of pulsars. Over the declination range $-80^{\\circ} < {\\delta} < 10^{\\circ}$ we detect 17 known pulsars with mean flux density greater than 0.3 Jy. We explore the variability properties of this sample on timescales of minutes to years. For three of these pulsars, PSR J0953+0755, PSR J0437-4715 and PSR J0630-2834 we observe interstellar scintillation and variability on timescales of greater than 2 minutes. One further pulsar, PSR J0034-0721, showed significant variability, the physical origins of which are difficult to determine. The dynamic spectra for PSR J0953+0755 and PSR J0437-4715 show discrete time and frequency structure consistent with diffractive interstellar scintillation and we present the scintillation bandwidth and timescales from these observations. The remaining pulsars within our sample were statistically non-variable. We also explore the spectral properties of this sample and find ...

  7. The intrinsic intensity modulation of PSR B1937+21 at 1410 MHz

    CERN Document Server

    Jenet, F A; Jenet, Fredrick A.; Gil, Janusz

    2004-01-01

    The single-pulse properties of the millisecond radio pulsar PSR B1937+21 are studied in the 1410 MHz radio band. Aside from occasional ``giant pulses'' occurring in restricted regions of pulse phase, the emission appears to be remarkably stable, showing no pulse-to-pulse fluctuations other then those induced by propagation through the interstellar medium. This type of behavior has not been seen in any other pulsar although it was seen in previous 430 MHz observations of this source. The stability of PSR B1937+21 can be understood in the context of the sparking gap model of radio pulsar emission. Given the emission properties of this source at 430 MHz, this model predicts that the emission at all higher frequencies will be just as stable. Since the stability depends on the outflow velocity of the emitting plasma, an upper bound may be placed on its Lorentz factor.

  8. The origin of the Guitar pulsar

    CERN Document Server

    Tetzlaff, Nina; Hohle, Markus M

    2009-01-01

    Among a sample of 140 OB associations and clusters, we want to identify probable parent associations for the Guitar pulsar (PSR B2224+65) which would then also constrain its age. For this purpose, we are using an Euler-Cauchy technique treating the vertical component of the galactic potential to calculate the trajectories of the pulsar and each association into the past. To include errors we use Monte-Carlo simulations varying the initial parameters within their error intervals. The whole range of possible pulsar radial velocities is taken into account during the simulations. We find that the Guitar pulsar most probably originated from the Cygnus OB3 association ~0.8 Myr ago inferring a current radial velocity of v_r~-30 km/s, consistent with the inclination of its bow shock.

  9. The origin of the Guitar pulsar

    Science.gov (United States)

    Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M.

    2009-11-01

    Among a sample of 140 OB associations and clusters, we want to identify probable parent associations for the Guitar pulsar (PSR B2224+65), which would then also constrain its age. For this purpose, we are using an Euler-Cauchy technique, treating the vertical component of the Galactic potential to calculate the trajectories of the pulsar and each association into the past. To include errors, we use Monte Carlo simulations varying the initial parameters within their error intervals. The whole range of possible pulsar radial velocities is taken into account during the simulations. We find that the Guitar pulsar most probably originated from the Cygnus OB3 association ~0.8Myr ago, inferring a current radial velocity of vr ~ -30kms-1, consistent with the inclination of its bow shock.

  10. X-Ray/GeV Emissions from Crab-like Pulsars in the LMC

    Science.gov (United States)

    Takata, J.; Cheng, K. S.

    2017-01-01

    We discuss X-ray and gamma-ray emissions from Crab-like pulsars, PSRs J0537-6910 and J0540-6919, in the Large Magellanic Cloud. Fermi-LAT observations have resolved the gamma-ray emissions from these two pulsars and found pulsed emissions from PSR J0540-6919. The total pulsed radiation in the X-ray/gamma-ray energy bands of PSR J0540-6919 is observed with efficiency {η }J0540∼ 0.06 (in 4π sr), which is about a factor of ten larger than {η }{Crab}∼ 0.006 of the Crab pulsar. Although PSR J0537-6910 has the highest spin-down power among currently known pulsars, the efficiency of the observed X-ray emissions is about two orders of magnitude smaller than that of PSR J0540-6919. This paper mainly discusses what causes the difference in the radiation efficiencies of these three energetic Crab-like pulsars. We discuss electron/positron acceleration and high-energy emission processes within the outer gap model. By solving the outer gap structure with the dipole magnetic field, we show that the radiation efficiency decreases as the inclination angle between the magnetic axis and the rotation axis increases. To explain the difference in the pulse profile and in the radiation efficiency, our model suggests that PSR J0540-6919 has an inclination angle much smaller than that of the Crab pulsar (here we assume the inclination angles of both pulsars are α Earth viewing angle, and that we see PSR J0537-6910 with an Earth viewing angle \\zeta \\gg 90^\\circ (or \\ll 90^\\circ ) measured from the spin axis, while we see PSR J0540-6919 with \\zeta ∼ 90^\\circ .

  11. High magnetic field pulsars and magnetars a unified picture

    CERN Document Server

    Zhang, B; Zhang, Bing; Harding, Alice K.

    2000-01-01

    We propose a unified picture of high magnetic field radio pulsars and magnetars by arguing that they are all rotating high-field neutron stars, but have different orientations of their magnetic axes with respective to their rotation axes. In strong magnetic fields where photon splitting suppresses pair creation near the surface, the high-field pulsars can have active inner accelerators while the anomalous X-ray pulsars cannot. This can account for the very different observed emission characteristics of the anomalous X-ray pulsar 1E 2259+586 and the high field radio pulsar PSR J1814-1744. A predicted consequence of this picture is that radio pulsars having surface magnetic field greater than about $2\\times 10^{14}$ G should not exist.

  12. Multiwavelength monitoring and X-ray brightening of Be X-ray binary PSR J2032+4127/MT91 213 on its approach to periastron

    Science.gov (United States)

    Ho, Wynn C. G.; Ng, C.-Y.; Lyne, Andrew G.; Stappers, Ben W.; Coe, Malcolm J.; Halpern, Jules P.; Johnson, Tyrel J.; Steele, Iain A.

    2017-01-01

    The radio and gamma-ray pulsar PSR J2032+4127 was recently found to be in a decades-long orbit with the Be star MT91 213, with the pulsar moving rapidly towards periastron. This binary shares many similar characteristics with the previously unique binary system PSR B1259-63/LS 2883. Here, we describe radio, X-ray, and optical monitoring of PSR J2032+4127/MT91 213. Our extended orbital phase coverage in radio, supplemented with Fermi LAT gamma-ray data, allows us to update and refine the orbital period to 45-50 yr and time of periastron passage to 2017 November. We analyse archival and recent Chandra and Swift observations and show that PSR J2032+4127/MT91 213 is now brighter in X-rays by a factor of ˜70 since 2002 and ˜20 since 2010. While the pulsar is still far from periastron, this increase in X-rays is possibly due to collisions between pulsar and Be star winds. Optical observations of the Hα emission line of the Be star suggest that the size of its circumstellar disc may be varying by ˜2 over time-scales as short as 1-2 months. Multiwavelength monitoring of PSR J2032+4127/MT91 213 will continue through periastron passage, and the system should present an interesting test case and comparison to PSR B1259-63/LS 2883.

  13. High-Energy Emission from the PSR B1259-63 System near Periastron

    CERN Document Server

    Tavani, M; Purcell, W; Hermsen, W; Kuiper, L; Kaaret, P E; Ford, E; Wilson, R B; Finger, M H; Harmon, B A; Zhang, S N; Mattox, J R; Thompson, D J; Arons, J

    1996-01-01

    We report the results of a CGRO 3-week observation of the binary system containing the 47 ms pulsar PSR B1259-63 orbiting around a Be star companion in a very eccentric orbit. The PSR B1259-63 binary is a unique system for the study of the interaction of a rapidly rotating pulsar with time-variable nebular surroundings. CGRO observed the PSR B1259-63 system in coincidence with its most recent periastron passage (January 3-23, 1994). Unpulsed and non-thermal hard X-ray emission was detected up to 200 keV, with a photon index $1.8 \\pm 0.2$ and a flux of ~4 mCrab, corresponding to a luminosity of a few 10^{34} erg/s at the distance of 2 kpc. The hard X-ray flux and spectrum detected by CGRO agrees with the X-ray emission measured by simultaneous ASCA observations. EGRET upper limits are significant, and exclude strong inverse Compton cooling in the PSR B1259-63 system. We interpret the observed non-thermal emission as synchrotron radiation of shocked electron/positron pairs of the relativistic pulsar wind intera...

  14. Discovery of Two New Pulsars in 47 Tucanae (NGC 104)

    CERN Document Server

    Pan, Zhichen; Li, Di; Ridolfi, Alessandro; Wang, Pei; Freire, Paulo

    2016-01-01

    We report the discovery of two new millisecond pulsars (PSRs J0024$-$7204aa and J0024$-$7204ab) in the globular cluster 47\\,Tucanae (NGC 104). Our results bring the total number of pulsars in 47\\,Tucanae to 25. These pulsars were discovered by reprocessing archival observations from the Parkes radio telescope. We reprocessed the data using a standard search procedure based on the PRESTO software package as well as using a new method in which we incoherently added the power spectra corresponding to $\\sim$1100\\,hr of observations. The newly discovered PSR~J0024$-$7204aa, has a pulse frequency of $\\rm \\sim$541\\,Hz (corresponding to a $\\rm \\sim$1.84 ms period), which is higher than any other pulsars currently known in the cluster and ranks 12$^{\\rm{th}}$ amongst all the currently known pulsars. The dispersion measure of this pulsar, 24.941(7)\\,cm$^{-3}$ pc, is the highest in the cluster. The second discovered pulsar, PSR~J0024$-$7204ab, is an isolated pulsar with a pulse frequency of $\\rm \\sim$270\\,Hz (correspond...

  15. Pulsar Magnetospheres and Pulsar Winds

    CERN Document Server

    Beskin, Vasily S

    2016-01-01

    Surprisingly, the chronology of nearly 50 years of the pulsar magnetosphere and pulsar wind research is quite similar to the history of our civilization. Using this analogy, I have tried to outline the main results obtained in this field. In addition to my talk, the possibility of particle acceleration due to different processes in the pulsar magnetosphere is discussed in more detail.

  16. THE TIMING OF NINE GLOBULAR CLUSTER PULSARS

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, Ryan S. [Physics Department, McGill University, 3600 Rue University, Montreal, QC H3A 2T8 (Canada); Freire, Paulo C. C. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Ransom, Scott M. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-4325 (United States); Jacoby, Bryan A., E-mail: rlynch@physics.mcgill.ca, E-mail: pfreire@mpifr-bonn.mpg.de, E-mail: sransom@nrao.edu, E-mail: bryan.jacoby@gmail.com [Aerospace Corporation, 15049 Conference Center Drive, Chantilly, VA 20151-3824 (United States)

    2012-02-01

    We have used the Robert C. Byrd Green Bank Telescope to time nine previously known pulsars without published timing solutions in the globular clusters (GCs) M62, NGC 6544, and NGC 6624. We have full timing solutions that measure the spin, astrometric, and (where applicable) binary parameters for six of these pulsars. The remaining three pulsars (reported here for the first time) were not detected enough to establish solutions. We also report our timing solutions for five pulsars with previously published solutions, and find good agreement with other authors, except for PSR J1701-3006B in M62. Gas in this system is probably responsible for the discrepancy in orbital parameters, and we have been able to measure a change in the orbital period over the course of our observations. Among the pulsars with new solutions we find several binary pulsars with very low mass companions (members of the so-called 'black widow' class) and we are able to place constraints on the mass-to-light ratio in two clusters. We confirm that one of the pulsars in NGC 6624 is indeed a member of the rare class of non-recycled pulsars found in GCs. We have also measured the orbital precession and Shapiro delay for a relativistic binary in NGC 6544. If we assume that the orbital precession can be described entirely by general relativity, which is likely, we are able to measure the total system mass (2.57190(73) M{sub Sun }) and companion mass (1.2064(20) M{sub Sun }), from which we derive the orbital inclination (sin i = 0.9956(14)) and the pulsar mass (1.3655(21) M{sub Sun }), the most precise such measurement ever obtained for a millisecond pulsar. The companion is the most massive known around a fully recycled pulsar.

  17. The braking index of PSR J1734-3333 and the magnetar population

    CERN Document Server

    Espinoza, Cristobal M; Kramer, Michael; Manchester, Richard N; Kaspi, Victoria

    2011-01-01

    PSR J1734-3333 is a radio pulsar rotating with a period P=1.17 s and slowing down with a period derivative Pdot=2.28 x 10^{-12}, the third largest among rotation-powered pulsars. These properties are midway between those of normal rotation-powered pulsars and magnetars, two populations of neutron stars that are notably different in their emission properties. Here we report on the measurement of the second period derivative of the rotation of PSR J1734-3333 and calculate a braking index n=0.9 +- 0.2. This value is well below 3, the value expected for an electromagnetic braking due to a constant magnetic dipole, and indicates that this pulsar may soon have the rotational properties of a magnetar. While there are several mechanisms which could lead to such a low braking index, we discuss this observation, together with the properties exhibited by some other high-Pdot rotation-powered pulsars, and interpret it as evidence of a possible evolutionary route for magnetars through a radio-pulsar phase, supporting a un...

  18. Low braking index of PSR J1734-3333: an interaction between fall-back disc and magnetic field?

    Science.gov (United States)

    Chen, Wen-Cong; Li, Xiang-Dong

    2016-01-01

    Recent timing observation reported that the radio pulsar PSR J1734-3333 with a rotating period P = 1.17 s is slowing down with a period derivative dot{P}=2.28× 10^{-12} s s^{-1}. Its derived braking index n = 0.9 ± 0.2 is the lowest value among young radio pulsars with the measured braking indices. In this Letter, we attempt to investigate the influence of the braking torque caused by the interaction between the fall-back disc and the strong magnetic field of the pulsar on the spin evolution of PSR J1734-3333. Analytical result show that this braking torque is obviously far more than that by magnetic dipole radiation for pulsars with spin period of >0.1 s, and play an important role during the spin-down of the pulsars. Our simulated results indicate that, for some typical neutron star parameters, the braking index and the period derivative approximately in agreement with the measured value of PSR J1734-3333 if the material inflow rate in the fall-back disc is 2 × 1017 g s- 1. In addition, our scenario can account for the measured braking indices of four young pulsars. However, our predicted X-ray luminosity are one to two order of magnitude higher than the observation. We proposed that this discrepancy may originate from the instability of fall-back disc.

  19. Pulsar-Black Hole Binaries in the Galactic Center

    CERN Document Server

    Faucher-Giguere, C -A

    2010-01-01

    Binaries consisting of a pulsar and a black hole (BH) are a holy grail of astrophysics, both for their significance for stellar evolution and for their potential application as probes of strong gravity. In spite of extensive surveys of our Galaxy and its system of globular clusters, no pulsar-black hole (PSR-BH) binary has been found to date. Clues as to where such systems might exist are therefore highly desirable. We show that if the central parsec around Sgr A* harbors a cluster of ~25,000 stellar BHs (as predicted by mass segregation arguments) and if it is also rich in recycled pulsar binaries (by analogy with globular clusters), then 3-body exchange interactions should produce PSR-BHs in the Galactic center. Simple estimates of the formation rate and survival time of these binaries suggest that a few PSR-BHs should be present in the central parsec today. The proposed formation mechanism makes unique predictions for the PSR-BH properties: 1) the binary would reside within ~1 pc of Sgr A*; 2) the pulsar w...

  20. Verification of f(R-gravity in binary pulsars

    Directory of Open Access Journals (Sweden)

    Dyadina Polina

    2016-01-01

    Full Text Available We develop the parameterized post-Keplerian approach for class of analytic f (R-gravity models. Using the double binary pulsar system PSR J0737-3039 data we obtain restrictions on the parameters of this class of f (R-models and show that f (R-gravity is not ruled out by the observations in strong field regime.

  1. Braking PSR J1734-3333 with a possible fall-back disk

    Science.gov (United States)

    Liu, Xiong-Wei; Xu, Ren-Xin; Qiao, Guo-Jun; Han, Jin-Lin; Tong, Hao

    2014-01-01

    The very small braking index of PSR J1734-3333, n = 0.9 ± 0.2, challenges the current theories of braking mechanisms in pulsars. We present a possible interpretation that this pulsar is surrounded by a fall-back disk and braked by it. A modified braking torque is proposed based on the competition between the magnetic energy density of the pulsar and the kinetic energy density of the fall-back disk. With this torque, a self-similar disk can fit all the observed parameters of PSR J1734-3333 with natural initial values of parameters. In this regime, the star will evolve to the region having anomalous X-ray pulsars and soft gamma repeaters in the P - Ṗ diagram in about 20 000 years and stay there for a very long time. The mass of the disk around PSR J1734-3333 in our model is about 10M⊕, similar to the observed mass of the disk around AXP 4U 0142+61.

  2. Observations of three young γ-ray pulsars with the Gran Telescopio Canarias

    Science.gov (United States)

    Mignani, R. P.; Rea, N.; Testa, V.; Marelli, M.; De Luca, A.; Pierbattista, M.; Shearer, A.; Torres, D. F.; De Oña Wilhelmi, E.

    2016-10-01

    We report the analysis of the first deep optical observations of three isolated γ-ray pulsars detected by the Fermi Gamma-ray Space Telescope: the radio-loud PSR J0248+6021 and PSR J0631+1036, and the radio-quiet PSR J0633+0632. The latter has also been detected in the X-rays. The pulsars are very similar in their spin-down age (τ ˜ 40-60 kyr), spin-down energy (dot{E} ˜ 10^{35} erg s-1), and dipolar surface magnetic field (B ˜ 3-5 × 1012 G). These pulsars are promising targets for multiwavelength observations, since they have been already detected in γ-rays and in radio or X-rays. None of them has been detected yet in the optical band. We observed the three pulsar fields in 2014 with the Spanish 10.4 m Gran Telescopio Canarias (GTC). We could not find any candidate optical counterpart to the three pulsars close to their most recent radio or Chandra positions down to 3σ limits of g' ˜ 27.3, g' ˜ 27, g' ˜ 27.3 for PSR J0248+6021, J0631+1036, and J0633+0632, respectively. From the inferred optical upper limits and estimated distance and interstellar extinction, we derived limits on the pulsar optical luminosity. We also searched for the X-ray counterpart to PSR J0248+6021 with Chandra but we did not detect the pulsar down to a 3σ flux limit of 5 × 10-14 erg cm-2 s-1 (0.3-10 keV). For all these pulsars, we compared the optical flux upper limits with the extrapolations in the optical domain of the γ-ray spectra and compared their multiwavelength properties with those of other γ-ray pulsars of comparable age.

  3. New COMPTEL results on pulsar studies at MeV energies

    Science.gov (United States)

    Hermsen, W.; Kuiper, L.; Schoenfelder, V.; Strong, A. W.; Bennett, K.; Much, R.; McConnell, M.; Ryan, J.; Carraminana, A.

    1997-01-01

    The Compton telescope (COMPTEL) onboard the Compton Gamma Ray Observatory (CGRO) detected the pulsar PSR B1951-32 at MeV energies, and found indications of a signal from PSR B0656+14. In the combined spectra from COMPTEL and the energetic gamma ray experiment telescope (EGRET) onboard CGRO, it can be seen that the maximum luminosities of these objects are reached in the COMPTEL energy range. These spectra can be compared with those from four other pulsars observed in MeV energies with COMPTEL. The spectral properties of five of the six pulsars, Vela, PSR B1509-58, PSR B1951-32 and PSR B0656+14, require breaks and bends at MeV energies. The sixth pulsar, the Crab pulsar, approximately follows a power law flux relation from keV to GeV energies. It is concluded that this spectral behavior may play a role in the discrimination between current gamma ray emission models.

  4. Toward an Understanding of the Periastron Puzzle of PSR B1259-63

    Institute of Scientific and Technical Information of China (English)

    Ren-Xin Xu

    2006-01-01

    Efforts are made to understand the timing behaviors (e.g., the jumps in the projected pulsar semimajor axis at the periastron passages) observed in the 13-year monitoring of PSR B1259-63. Planet-like objects are suggested to orbit around the Be star, which may gravitationally perturb the (probably low mass) pulsar when it passes through periastron.An accretion disk should exist outside the pulsar's light cylinder, which creates a spindown torque on the pulsar due to the propeller effect. The observed negative braking index and the discrepant timing residuals close to periastron could be related to the existence of a disk with a varying accretion rate. A speculation is presented that the accretion rate may increase on a long timescale in order to explain the negative braking index.

  5. Observation and Simulation of the Variable Gamma-ray Emission from PSR J2021+4026

    Science.gov (United States)

    Ng, C. W.; Takata, J.; Cheng, K. S.

    2016-07-01

    Pulsars are rapidly spinning and highly magnetized neutron stars, with highly stable rotational periods and a gradual spin-down over a long timescale due to the loss of radiation. Glitches refer to events that suddenly increase the rotational speed of a pulsar. The exact causes of glitches and the resulting processes are not fully understood. It is generally believed that couplings between the normal matter and superfluid components, and starquakes, are the common causes of glitches. In this study, one famous glitching pulsar, PSR J2021+4026, is investigated. PSR J2021+4026 is the first variable gamma-ray pulsar observed by Fermi. From gamma-ray observations, it is found that the pulsar experienced a significant flux drop, an increase in the spin-down rate, a change in the pulse profile and a shift in the spectral cut-off to a lower energy, simultaneously around 2011 October 16. To explain these effects on high-energy emissions by the glitch of PSR J2021+4026, we hypothesized the glitch to be caused by the rearrangement of the surface magnetic field due to crustal plate tectonic activities on the pulsar, which was triggered by a starquake. In this glitch event, the inclination angle of the magnetic dipole axis was slightly shifted. This proposition is then tested by numerical modeling using a three-dimensional two-layer outer gap model. The simulation results indicate that a modification of the inclination angle can affect the pulse profile and the spectral properties, which can explain the observation changes after the glitch.

  6. Recently discovered pulsars and unidentified EGRET sources

    CERN Document Server

    Torres, D F; Camilo, F M; Torres, Diego F.; Butt, Yousaf M.; Camilo, Fernando

    2001-01-01

    We present a correlative study between all unidentified EGRET sources at low Galactic latitudes and the newly discovered pulsars in the released portion of the Parkes multibeam radio survey. We note 14 positional coincidences: eight of these are ``Vela-like'' pulsars, with relatively small periods, small characteristic ages, and high spin-down luminosities. Three of these coincidences have been investigated by D'Amico et al. (2001) and Camilo et al. (2001). Among the others, we argue that PSR J1015-5719 may plausibly generate part of the high energy radiation observed from 3EG J1014-5705. Three additional interesting cases are: 3EG J1410-6147 and either of PSRs J1412-6145 or J1413-6141, if the pulsars are at the estimated distance of the coincident SNR G312.4-0.4; and 3EG J1639-4702/PSR J1637-4642. The remaining positional coincidences between the EGRET sources and the newly discovered pulsars are almost certainly spurious.

  7. Gamma-ray binaries: pulsars in disguise ?

    CERN Document Server

    Dubus, G

    2006-01-01

    LS 5039 and LSI +61 303 are unique amongst high-mass X-ray binaries (HMXB) for their spatially-resolved radio emission and their counterpart at >GeV gamma-ray energies, canonically attributed to non-thermal particles in an accretion-powered relativistic jet. The only other HMXB known to emit very high energy (VHE) gamma-rays, PSR B1259-63, harbours a non-accreting millisecond pulsar. I investigate whether the interaction of the relativistic wind from a young pulsar with the wind from its stellar companion, as in PSR B1259-63, constitutes a viable scenario to explain the observations of LS 5039 and LSI +61 303. Emission would arise from the shocked pulsar wind material, which then flows away to large distances in a comet-shape tail, reproducing on a smaller scale what is observed in isolated, high motion pulsars interacting with the ISM. Simple expectations for the SED are derived and are shown to depend on few input parameters. Detailed modelling of the particle evolution is compared to the observations from ...

  8. A Bayesian method for pulsar template generation

    CERN Document Server

    Imgrund, M; Kramer, M; Lesch, H

    2015-01-01

    Extracting Times of Arrival from pulsar radio signals depends on the knowledge of the pulsars pulse profile and how this template is generated. We examine pulsar template generation with Bayesian methods. We will contrast the classical generation mechanism of averaging intensity profiles with a new approach based on Bayesian inference. We introduce the Bayesian measurement model imposed and derive the algorithm to reconstruct a "statistical template" out of noisy data. The properties of these "statistical templates" are analysed with simulated and real measurement data from PSR B1133+16. We explain how to put this new form of template to use in analysing secondary parameters of interest and give various examples: We implement a nonlinear filter for determining ToAs of pulsars. Applying this method to data from PSR J1713+0747 we derive ToAs self consistently, meaning all epochs were timed and we used the same epochs for template generation. While the average template contains fluctuations and noise as unavoida...

  9. Profile Stochasticity in PSR J1909-3744

    CERN Document Server

    Lentati, L

    2015-01-01

    We extend the recently introduced Bayesian framework `Generative Pulsar Timing Analysis' to incorporate both pulse jitter (high frequency variation in the arrival time of the pulse) and epoch to epoch stochasticity in the shape of the pulse profile. This framework allows for a full timing analysis to be performed on the folded profile data, rather than the site arrival times as is typical in most timing studies. We apply this extended framework both to simulations, and to an 11 yr, 10 cm data set for PSR J1909$-$3744. Using simulations, we show that temporal profile variation can induce timing noise in the residuals that when performing a standard timing analysis is highly covariant with the signal expected from a gravitational wave (GW) background. When working in the profile domain, these variations are de-correlated from the expected GW signal, resulting in significant improvement in the obtained upper limits. Using the PSR J1909$-$3744 data set from the Parkes Pulsar Timing Array project, we find signific...

  10. Binary Millisecond Pulsar Discovery via Gamma-Ray Pulsations

    CERN Document Server

    Pletsch, H J; Fehrmann, H; Allen, B; Kramer, M; Aulbert, C; Ackermann, M; Ajello, M; de Angelis, A; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Borgland, A W; Bottacini, E; Brandt, T J; Bregeon, J; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Celik, Ö; Charles, E; Chaves, R C G; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Cutini, S; D'Ammando, F; Dermer, C D; Digel, S W; Drell, P S; Drlica-Wagner, A; Dubois, R; Dumora, D; Favuzzi, C; Ferrara, E C; Franckowiak, A; Fukazawa, Y; Fusco, P; Gargano, F; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Godfrey, G; Grenier, I A; Grondin, M -H; Grove, J E; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hartog, P R den; Hayashida, M; Hays, E; Hill, A B; Hou, X; Hughes, R E; Johannesson, G; Jackson, M S; Jogler, T; Johnson, A S; Johnson, W N; Kataoka, J; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Larsson, S; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Massaro, F; Mayer, M; Mazziotta, M N; McEnery, J E; Mehault, J; Michelson, P F; Mitthumsiri, W; Mizuno, T; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Nemmen, R; Nuss, E; Ohno, M; Ohsugi, T; Omodei, N; Orienti, M; Orlando, E; de Palma, F; Paneque, D; Perkins, J S; Piron, F; Pivato, G; Porter, T A; Raino, S; Rando, R; Ray, P S; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Romani, R W; Romoli, C; Sanchez, D A; Parkinson, P M Saz; Schulz, A; Sgro, C; Silva, E do Couto e; Siskind, E J; Smith, D A; Spandre, G; Spinelli, P; Suson, D J; Takahashi, H; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Tinivella, M; Troja, E; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Waite, A P; Winer, B L; Wood, K S; Wood, M; Yang, Z; Zimmer, S; 10.1126/science.1229054

    2012-01-01

    Millisecond pulsars (MSPs), old neutron stars spun-up by accreting matter from a companion star, can reach high rotation rates of hundreds of revolutions per second. Until now, all such "recycled" rotation-powered pulsars have been detected by their spin-modulated radio emission. In a computing-intensive blind search of gamma-ray data from the Fermi Large Area Telescope (with partial constraints from optical data), we detected a 2.5-millisecond pulsar, PSR J1311-3430. This unambiguously explains a formerly unidentified gamma-ray source that had been a decade-long enigma, confirming previous conjectures. The pulsar is in a circular orbit with an orbital period of only 93 minutes, the shortest of any spin-powered pulsar binary ever found.

  11. Low braking index of PSR J1734-3333: an interaction between fall-back disk and magnetic field?

    CERN Document Server

    Chen, Wen-Cong

    2015-01-01

    Recent timing observation reported that the radio pulsar PSR J1734 - 3333 with a rotating period $P=1.17~\\rm s$ is slowing down with a period derivative $\\dot{P}=2.28\\times 10^{-12}\\rm s\\,s^{-1}$. Its derived braking index $n=0.9 \\pm 0.2$ is the lowest value among young radio pulsars with the measured braking indices. In this Letter, we attempt to investigate the influence of the braking torque caused by the interaction between the fall-back disk and the strong magnetic field of the pulsar on the spin evolution of PSR J1734 - 3333. Analytical result show that this braking torque is obviously far more than that by magnetic dipole radiation for pulsars with spin period of $> 0.1$ s, and play an important role during the spin-down of the pulsars. Our simulated results indicate that, for some typical neutron star parameters, the braking index and the period derivative approximately in agreement with the measured value of PSR J1734 - 3333 if the material inflow rate in the fallback disk is $2 \\times 10^{17} \\rm g\\...

  12. Observation and Simulation of the Variable Gamma-ray Emission from PSR~J2021+4026

    CERN Document Server

    Ng, C W; Cheng, K S

    2016-01-01

    Pulsars are rapidly spinning and highly magnetized neutron stars, with highly stable rotational period and gradual spin-down over a long timescale due to the loss of radiation. Glitches refer to the events that suddenly increase the rotational speed of a pulsar. The exact causes of glitches and the resulting processes are not fully understood. It is generally believed that couplings between the normal matter and the superfluid components, and the starquakes, are the common causes of glitches. In this study, one famous glitching pulsar, PSR~J2021+4026, is investigated. PSR~J2021+4026 is the first variable gamma-ray pulsar observed by Fermi. From the gamma-ray observations, it is found that the pulsar experienced a significant flux drop, an increase in the spin-down rate, a change in the pulse profile and a shift in the spectral cut-off to a lower energy, simultaneously around 2011 October 16. To explain these effects on the high-energy emissions by the glitch of PSR~J2021+4026, we hypothesized the glitch to be...

  13. Testing gravity with pulsar scintillation measurements

    Science.gov (United States)

    Yang, Huan; Nishizawa, Atsushi; Pen, Ue-Li

    2017-04-01

    We propose to use pulsar scintillation measurements to test predictions of alternative theories of gravity. Compared to single-path pulsar timing measurements, the scintillation measurements can achieve an accuracy of one part in a thousand within one wave period, which means picosecond scale resolution in time, due to the effect of multipath interference. Previous scintillation measurements of PSR B 0834 +06 have hours of data acquisition, making this approach sensitive to mHz gravitational waves. Therefore it has unique advantages in measuring the effect of gravity or other mechanisms on light propagation. We illustrate its application in constraining the scalar gravitational-wave background, in which case the sensitivities can be greatly improved with respect to previous limits. We expect much broader applications in testing gravity with existing and future pulsar scintillation observations.

  14. Testing Gravity with Pulsar Scintillation Measurements

    CERN Document Server

    Yang, Huan; Pen, Ue-Li

    2016-01-01

    We propose to use pulsar scintillation measurements to test predictions of alternative theories of gravity. Comparing to single-path pulsar timing measurements, the scintillation measurements can achieve a factor of 10^5 improvement in timing accuracy, due to the effect of multi-path interference. Previous scintillation measurements of PSR B0834+06 have data acquisition for hours, making this approach sensitive to mHz gravitational waves. Therefore it has unique advantages in measuring gravitational effect or other mechanisms (at mHz and above frequencies) on light propagation. We illustrate its application in constraining scalar gravitational-wave background, in which case the sensitivities can be greatly improved with respect to previous limits. We expect much broader applications in testing gravity with existing and future pulsar scintillation observations.

  15. Fermi LAT observations of PSR J1119-6127 before and after its recent bursts

    Science.gov (United States)

    Tam, P. H. Thomas

    2016-08-01

    We report on the Fermi LAT observations of PSR J1119-6127, a rotation-powered pulsar with high magnetic field that showed two magnetar-like bursts on 2016-07-27 13:02:07.91 UT and 2016-07-28 01:27:51 UT, recorded by the Fermi GBM and Swift BAT instruments, respectively (Kennea et al., GCN Circ. 19735/ATel #9274; Younes et al., GCN Circ. 19736).

  16. The Timing of Nine Globular Cluster Pulsars

    CERN Document Server

    Lynch, Ryan S; Ransom, Scott M; Jacoby, Bryan A

    2011-01-01

    We have used the Robert C. Byrd Green Bank Telescope to time nine previously known pulsars without published timing solutions in the globular clusters M62, NGC 6544, and NGC 6624. We have full timing solutions that measure the spin, astrometric, and (where applicable) binary parameters for six of these pulsars. The remaining three pulsars (reported here for the first time) were not detected enough to establish solutions. We also report our timing solutions for five pulsars with previously published solutions, and find good agreement with past authors, except for PSR J1701-3006B in M62. Gas in this system is probably responsible for the discrepancy in orbital parameters, and we have been able to measure a change in the orbital period over the course of our observations. Among the pulsars with new solutions we find several binary pulsars with very low mass companions (members of the so-called "black widow" class) and we are able to place constraints on the mass-to-light ratio in two clusters. We confirm that on...

  17. Pulsar Navigation in the Solar System

    CERN Document Server

    Dong, Jiang

    2008-01-01

    The X-ray Pulsar-based Autonomous Navigation(XNAV) were recently tested which use the Crab pulsar (PSR B0531+21) in the USA Experiment on flown by the Navy on the Air Force Advanced Research and Global Observation Satellite (ARGOS) under the Space Test Program. It provide the way that the spacecraft could autonomously determine its position with respect to an inertial origin. Now I analysis the sensitivity of the exist instrument and the signal process to use radio pulsar navigation and discuss the integrated navigation use pulsar,then give the different navigation mission analysis and design process basically which include the space, the airborne, the ship and the land of the planet or the lunar.So the pulsar navigation can give the continuous position in deep spaces, that means we can freedom fly successfully in the solar system use celestial navigation that include pulsar and traditional star sensor.It also can less or abolish the depend of Global Navigation Satellite System which include GPS, GRONSS, Gali...

  18. Spin Tilts in the Double Pulsar Reveal Off-Center Supernova Kick and Tumble

    CERN Document Server

    Farr, Will M; Lyutikov, Maxim; Kalogera, Vassiliki

    2011-01-01

    The system PSR J0737-3039 is the only binary pulsar known to consist of two radio pulsars (PSR J0737-3039 A and PSR J0737-3039 B). This configuration allows measurements of spin orientation for both pulsars: pulsar A's spin is tilted from the orbital angular momentum by no more than 14 degrees; pulsar B's by 130 degrees. This spin-spin misalignment requires that the origin of most of B's spin is its supernova; the spin could originate from a substantial off-center kick, causing pulsar B to tumble to its misaligned state. Under the typical assumption of an instantaneous kick and using current constraints on the kick magnitude, it must have been displaced from the center of mass of the exploding star by at least 1 km and probably 5--10 km. Regardless of the details of the process that produced pulsar B's current spin, the orientation of the spins in the J0737-3039 system provides a direct, unique constraint on angular momentum production in supernovae.

  19. XMM-Newton Observations of Four Millisecond Pulsars

    Science.gov (United States)

    Zavlin, Vyacheslav E.

    2005-01-01

    I present an analysis of the XMM-Newton observations of four millisecond pulsars, J0437-4715, J2124-3358, J1024-0719, and J0034-0534. The new data provide strong evidence of thermal emission in the X-ray flux detected from the first three objects. This thermal component is best interpreted as radiation from pulsar polar caps covered with a nonmagnetic hydrogen atmosphere. A nonthermal power-law component, dominating at energies E greater than or equal to 3 keV, can also be present in the detected X-ray emission. For PSR J0437-4715, the timing analysis reveals that the shape and pulsed fraction of the pulsar light curves are energy dependent. This, together with the results obtained from the phase-resolved spectroscopy, supports the two-component (thermal plus nonthermal) interpretation of the pulsar's X-ray radiation. Highly significant pulsations have been found in the X-ray flux of PSRs 52124-3358 and 51024-0719. For PSR 50034-0534, a possible X-ray counterpart of the radio pulsar has been suggested. The inferred properties of the detected thermal emission are compared with predictions of radio pulsar models.

  20. X-ray Observations of High-B Radio Pulsars

    CERN Document Server

    Olausen, S A; Vogel, J K; Kaspi, V M; Lyne, A G; Espinoza, C M; Stappers, B W; Manchester, R N; McLaughlin, M A

    2013-01-01

    The study of high-magnetic-field pulsars is important for examining the relationships between radio pulsars, magnetars, and X-ray-isolated neutron stars (XINSs). Here we report on X-ray observations of three such high-magnetic-field radio pulsars. We first present the results of a deep XMM-Newton observation of PSR J1734-3333, taken to follow up on its initial detection in 2009. The pulsar's spectrum is well fit by a blackbody with a temperature of 300 +/- 60 eV, with bolometric luminosity L_bb = 2.0(+2.2 -0.7)e+32 erg/s = 0.0036E_dot for a distance of 6.1 kpc. We detect no X-ray pulsations from the source, setting a 1 sigma upper limit on the pulsed fraction of 60% in the 0.5-3 keV band. We compare PSR J1734-3333 to other rotation-powered pulsars of similar age and find that it is significantly hotter, supporting the hypothesis that the magnetic field affects the observed thermal properties of pulsars. We also report on XMM-Newton and Chandra observations of PSRs B1845-19 and J1001-5939. We do not detect eit...

  1. 17 and 24 GHz observations of southern pulsars

    CERN Document Server

    Keith, M J; Levin, L; Bailes, M

    2011-01-01

    We present observations of PSRs J0437-4715, J0738-4042, J0835-4510, J0908-4913, J1048-5832, J1622-4950, J1644-4559, J1721-3532 and J1740-3015 at 17 GHz using the Parkes radio telescope. All 9 were detected at 17 GHz, additionally, we detected PSR J0835-4510 and J1622-4950 at 24 GHz. Polarisation profiles of each pulsar and the variation with frequency are discussed. In general, we find that the highly polarised edge components of young pulsars continue to dominate their profiles at 17 GHz. Older pulsars (>10^5 years) appear to be almost completely depolarised. Our detection of PSR J0437-4715 is the highest frequency observation of a millisecond pulsar to date, and implies a luminosity at 17 GHz of 14 {\\mu}Jy kpc^2, and a mean spectral index of 2.2. We find that the spectral index of the magnetar PSR J1622-4950 is flat between 1.4 and 24 GHz, similar to the other known radio magnetars XTE J1810-197 and 1E 1547.0-5408. The profile is similar to that at 3.1 GHz, and is highly linearly polarised. Analysis of the ...

  2. Ordinary X-rays from Three Extraordinary Millisecond Pulsars: XMM-Newton Observations of PSRs J0337+1715, J0636+5129, and J0645+5158

    CERN Document Server

    Spiewak, Renée; Archibald, Anne; Gentile, Peter; Hessels, Jason; Lorimer, Duncan; Lynch, Ryan; McLaughlin, Maura; Ransom, Scott; Stairs, Ingrid; Stovall, Kevin

    2016-01-01

    We present the first X-ray observations of three recently discovered millisecond pulsars (MSPs) with interesting characteristics: PSR J0337+1715, PSR J0636+5129, and PSR J0645+5158. PSR J0337+1715 is a fast-spinning, bright, and so-far unique MSP in a hierarchical triple system with two white dwarf (WD) companions. PSR J0636+5129 is a MSP in a very tight 96-min orbit with a low-mass, 8 $M_J$ companion. PSR J0645+5158 is a nearby, isolated MSP with a very small duty cycle (1-2%), which has led to its inclusion in high-precision pulsar timing programs. Using data from XMM-Newton, we have analyzed X-ray spectroscopy for these three objects, as well as optical/ultraviolet photometry for PSR J0337+1715. The X-ray data for each are largely consistent with expectations for most MSPs with regards to the ratios of thermal and non-thermal emission. We discuss the implications of these data on the pulsar population, and prospects for future observations of these pulsars.

  3. Magnetic field growth in young glitching pulsars with a braking index

    CERN Document Server

    Ho, Wynn C G

    2015-01-01

    In the standard scenario for spin evolution of isolated neutron stars, a young pulsar slows down with a surface magnetic field B that does not change. Thus the pulsar follows a constant B trajectory in the phase space of spin period and spin period time derivative. Such an evolution predicts a braking index n = 3 while the field is constant and n > 3 when the field decays. This contrasts with all nine observed values being n < 3. Here we consider a magnetic field that is buried soon after birth and diffuses to the surface. We use a model of a growing surface magnetic field to fit observations of the three pulsars with lowest n: PSR J0537-6910 with n = -1.5, PSR B0833-45 (Vela) with n = 1.4, and PSR J1734-3333 with n = 0.9. By matching the age of each pulsar, we determine their magnetic field and spin period at birth and confirm the magnetar-strength field of PSR J1734-3333. Our results indicate all three pulsars formed in a similar way to central compact objects (CCOs), with differences due to the amount o...

  4. X-ray/GeV emissions from Crab-like pulsars in LMC

    CERN Document Server

    Takata, J

    2016-01-01

    We discuss X-ray and gamma-ray emissions from Crab-like pulsars, PSRs~J0537-6910 and~J0540-6919, in Large Magellanic Cloud. Fermi-LAT observations have resolved the gamma-ray emissions from these two pulsars and found the pulsed emissions from PSR~J0540-6919. The total pulsed radiation in the X-ray/gamma-ray energy bands of PSR~J0540-6919 is observed with the efficiency $\\eta_{J0540}\\sim 0.06$ (in 4$\\pi$ sr), which is about a factor of ten larger than $\\eta_{Crab}\\sim 0.006$ of the Crab pulsar. Although PSR~J0537-6910 has the highest spin-down power among currently known pulsars, the efficiency of the observed X-ray emissions is about two orders of magnitude smaller than that of PSR~J0540-6919. This paper mainly discusses what causes the difference in the radiation efficiencies of these three energetic Crab-like pulsars. We discuss electron/positron acceleration and high-energy emission processes within the outer gap model. By solving the outer gap structure with the dipole magnetic field, we show that the ra...

  5. Observations of three young gamma-ray pulsars with the Gran Telescopio Canarias

    CERN Document Server

    Mignani, R P; Testa, V; Marelli, M; De Luca, A; Pierbattista, M; Shearer, A; Torres, D F; Wilhelmi, E De Ona

    2016-01-01

    We report the analysis of the first deep optical observations of three isolated $\\gamma$-ray pulsars detected by the {\\em Fermi Gamma-ray Space Telescope}: the radio-loud PSR\\, J0248+6021 and PSR\\, J0631+1036, and the radio-quiet PSR\\, J0633+0632. The latter has also been detected in the X rays. The pulsars are very similar in their spin-down age ($\\tau \\sim$40--60 kyrs), spin-down energy ($\\dot{E} \\sim10^{35}$ erg s$^{-1}$), and dipolar surface magnetic field ($B \\sim 3$--$5\\times10^{12}$ G). These pulsars are promising targets for multi-wavelength observations, since they have been already detected in $\\gamma$ rays and in radio or X-rays. None of them has been detected yet in the optical band. We observed the three pulsar fields in 2014 with the Spanish 10.4m Gran Telescopio Canarias (GTC). We could not find any candidate optical counterpart to the three pulsars close to their most recent radio or {\\em Chandra} positions down to $3 \\sigma$ limits of $g'\\sim27.3$, $g'\\sim27$, $g'\\sim27.3$ for PSR\\, J0248+602...

  6. The High Time Resolution Universe Pulsar Survey IV: Discovery and polarimetry of millisecond pulsars

    CERN Document Server

    Keith, M J; Bailes, M; Bates, S D; Bhat, N D R; Burgay, M; Burke-Spolaor, S; D'Amico, N; Jameson, A; Kramer, M; Levin, L; Milia, S; Possenti, A; Stappers, B W; van Straten, W; Parent, D

    2011-01-01

    We present the discovery of six millisecond pulsars (MSPs) in the High Time Resolution Universe (HTRU) survey for pulsars and fast transients carried out with the Parkes radio telescope. All six are in binary systems with approximately circular orbits and are likely to have white dwarf companions. PSR J1017-7156 has a high flux density and a narrow pulse width, making it ideal for precision timing experiments. PSRs J1446-4701 and J1125-5825 are coincident with gamma-ray sources, and folding the high-energy photons with the radio timing ephemeris shows evidence of pulsed gamma-ray emission. PSR J1502-6752 has a spin period of 26.7 ms, and its low period derivative implies that it is a recycled pulsar. The orbital parameters indicate it has a very low mass function, and therefore a companion mass much lower than usually expected for such a mildly recycled pulsar. In addition we present polarisation profiles for all 12 MSPs discovered in the HTRU survey to date. Similar to previous observations of MSPs, we find ...

  7. Radio and Gamma-Ray Constraints on the Emission Geometry and Birthplace of PSR J2043+2740

    CERN Document Server

    Noutsos, A; Ackermann, M; Ajello, M; Ballet, J; Barbiellini, G; Baring, M G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Buehler, R; Busetto, G; Caliandro, G A; Cameron, R A; Camilo, F; Caraveo, P A; Casandjian, J M; Cecchi, C; Celik, O; Chaty, S; Chekhtman, A; Chiang, J; Ciprini, S; Claus, R; Cognard, I; Cohen-Tanugi, J; Colafrancesco, S; Cutini, S; Dermer, C D; de Palma, F; Drell, P S; Dumora, D; Espinoza, C M; Favuzzi, C; Ferrara, E C; Focke, W B; Frailis, M; Freire, P C C; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Godfrey, G; Grandi, P; Grenier, I A; Grove, J E; Guillemot, L; Guiriec, S; Harding, A K; Hughes, R E; Jackson, M S; Johannesson, G; Johnson, A S; Johnson, T J; Johnson, W N; Johnston, S; Kamae, T; Katagiri, H; Kataoka, J; Knoedlseder, J; Kramer, M; Kuss, M; Lande, J; Lee, S -H; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Lyne, A G; Makeev, A; Marelli, M; Mazziotta, M N; McEnery, J E; Mehault, J; Michelson, P F; Mizuno, T; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Naumann-Godo, M; Nolan, P L; Nuss, E; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Persic, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rain, S; Ray, P S; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Romani, R W; Sadrozinski, H F -W; Sander, A; Parkinson, P M Saz; Sgro, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Stappers, B W; Strickman, M S; Suson, D J; Takahashi, H; Tanaka, T; Theureau, G; Thompson, D J; Thorsett, S E; Tibolla, O; Torres, D F; Tramacere, A; Usher, T L; Vandenbroucke, J; Vianello, G; Vilchez, N; Villata, M; Vitale, V; von Kienlin, A; Waite, A P; Wang, P; Watters, K; Weltevrede, P; Winer, B L; Wood, K S; Ziegler, M

    2010-01-01

    We report on the first year of Fermi gamma-ray observations of pulsed high-energy emission from the old PSR J2043+2740. The study of the gamma-ray efficiency of such old pulsars gives us an insight into the evolution of pulsars' ability to emit in gammma rays as they age. The gamma-ray lightcurve of this pulsar above 0.1 GeV is clearly defined by two sharp peaks, 0.353+/-0.035 periods apart. We have combined the gamma-ray profile characteristics of PSR J2043+2740 with the geometrical properties of the pulsar's radio emission, derived from radio polarization data, and constrained the pulsar-beam geometry in the framework of a Two Pole Caustic and an Outer Gap model. The ranges of magnetic inclination and viewing angle were determined to be {alpha,zeta}~{52-57,61-68} for the Two Pole Caustic model, and {alpha,zeta}~{62-73,74-81} and {alpha,zeta}~{72-83,60-75} for the Outer Gap model. Based on this geometry, we assess possible birth locations for this pulsar and derive a likely proper motion, sufficiently high t...

  8. Progenitor neutron stars of the lightest and heaviest millisecond pulsars

    CERN Document Server

    Fortin, M; Haensel, P; Zdunik, J L

    2014-01-01

    Recent mass measurements of two binary millisecond pulsars, PSR J1614-2230 and PSR J0751+1807 with a mass M=1.97+/-0.04 Msun and M=1.26+/-0.14 Msun respectively indicate a large span of masses for such objects, and possibly also a broad spectrum of neutron star masses born in core-collapse supernovae. Starting from a zero-age main sequence binary stage, we aim at inferring the masses of the progenitor neutron star of PSR J1614-2230 and PSR J0751+1807 by taking into account the differences in the evolutionary stages preceding their formation. Using simulations for the evolution of binary stars we reconstruct the evolutionary tracks leading to the formation of PSR J1614-2230 and PSR J0751+1807. We analyse in detail the spin evolution due to the accretion of matter from a disk in the medium-mass/low-mass X-ray binary. General relativistic effects and the damping of surface magnetic field associated with accretion are accounted for. We consider two equations of state of dense matter, one for purely nucleonic matt...

  9. Reduced spin-down rate of PSR J0738-4042 explained as due to an asteroid disruption event

    Science.gov (United States)

    Yu, Yong-Bo; Huang, Yong-Feng

    2016-05-01

    Long term observations by Brook et al. reveal that the derivative of rotational frequency of PSR J0738-4042 changed abruptly in 2005. Originally, the spin-down rate was relatively stable, with the rotational frequency derivative being -1.14×10-14 s-2. After September 2005, the derivative began to rise. About 1000 days later, it arrived at another relatively stable value of about -0.98 × 10-14 s-2, indicating that the pulsar is spinning-down relatively slowly. To explain the observed change in spin-down rate, we resort to an asteroid disrupted by PSR J0738-4042. In our model, the orbital angular momentum of the asteroid is assumed to be parallel to that of the rotating pulsar, so that the pronounced reduction in the spin-down rate can be naturally explained as due to the transfer of angular momentum from the disrupted material to the central pulsar. The derived magnetospheric radius is about 7.0 × 109 cm, which is smaller than the tidal disruption radius (8.7 × 1010 cm). Our model is self-consistent. It is shown that the variability in the spin-down rate of PSR J0738-4042 can be quantitatively accounted for by accretion from the asteroid disrupted by the central pulsar.

  10. Einstein@Home Discovery of a PALFA Millisecond Pulsar in an Eccentric Binary Orbit

    NARCIS (Netherlands)

    Knispel, B.; Lyne, A.G.; Stappers, B.W.; Freire, P.C.C.; Lazarus, P.; Allen, B.; Aulbert, C.; Bock, O.; Bogdanov, S.; Brazier, A.; Camilo, F.; Cardoso, F.; Chatterjee, S.; Cordes, J.M.; Crawford, F.; Deneva, J.S.; Eggenstein, H.B.; Fehrmann, H.; Ferdman, R.; Hessels, J.W.T.; Jenet, F.A.; Karako-Argaman, C.; Kaspi, V.M.; van Leeuwen, J.; Lorimer, D.R.; Lynch, R.; Machenschalk, B.; Madsen, E.; McLaughlin, M.A.; Patel, C.; Ransom, S.M.; Scholz, P.; Siemens, X.; Spitler, L.G.; Stairs, I.H.; Stovall, K.; Swiggum, J.K.; Venkataraman, A.; Wharton, R.S.; Zhu, W.W.

    2015-01-01

    We report the discovery of the millisecond pulsar (MSP) PSR J1950+2414 (P = 4.3 ms) in a binary system with an eccentric (e = 0.08) 22 day orbit in Pulsar Arecibo L-band Feed Array survey observations with the Arecibo telescope. Its companion star has a median mass of 0.3 M⊙ and is most likely a whi

  11. SPIN TILTS IN THE DOUBLE PULSAR REVEAL SUPERNOVA SPIN ANGULAR-MOMENTUM PRODUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Farr, Will M.; Kremer, Kyle; Kalogera, Vassiliki [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Lyutikov, Maxim, E-mail: w-farr@northwestern.edu, E-mail: kylekremer2012@u.northwestern.edu, E-mail: vicky@northwestern.edu, E-mail: lyutikov@purdue.edu [Physics Department, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States)

    2011-12-01

    The system PSR J0737-3039 is the only binary pulsar known to consist of two radio pulsars (PSR J0737-3039 A and PSR J0737-3039 B). This unique configuration allows measurements of spin orientation for both pulsars: pulsar A's spin is tilted from the orbital angular momentum by no more than 14 deg at 95% confidence; pulsar B's by 130 {+-} 1 deg at 99.7% confidence. This spin-spin misalignment requires that the origin of most of B's present-day spin is connected to the supernova that formed pulsar B. Under the simplified assumption of a single, instantaneous kick during the supernova, the spin could be thought of as originating from the off-center nature of the kick, causing pulsar B to tumble to its misaligned state. With this assumption, and using current constraints on the kick magnitude, we find that pulsar B's instantaneous kick must have been displaced from the center of mass of the exploding star by at least 1 km and probably 5-10 km. Regardless of the details of the kick mechanism and the process that produced pulsar B's current spin, the measured spin-spin misalignment in the double pulsar system provides an empirical, direct constraint on the angular momentum production in this supernova. This constraint can be used to guide core-collapse simulations and the quest for understanding the spins and kicks of compact objects.

  12. An Eccentric Binary Millisecond Pulsar in the Galactic Plane

    Science.gov (United States)

    Champion, David J.; Ransom, Scott M.; Lazarus, Patrick; Camilo, Fernando; Bassa, Cess; Kaspi, Victoria M.; Nice, David J.; Freire, Paulo C. C.; Stairs, Ingrid H.; vanLeeuwen, Joeri; Stappers, Ben W.; Cordes, James M.; Hessels, Jason W. T.; Lorimer, Duncan R.; Arzoumanian, Zaven; Backer, Don C.; Bhat, N. D. Ramesh; Chatterjee, Shami; Cognard, Ismael; Deneva, Julia S.; Faucher-Giguere, Claude-Andre; Gaensler, Bryan M.; Han, JinLin; Jenet, Fredrick A.; Kasian, Laura

    2008-01-01

    Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 milliseconds in a highly eccentric (e = 0.44) 95-day orbit around a solar mass (M.) companion. Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars. Alternative formation scenarios involve recycling a neutron star in a globular cluster, then ejecting it into the Galactic disk, or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74 +/- 0.04 Solar Mass, an unusually high value.

  13. JPL pulsar timing observations. IV - Excess phase noise

    Science.gov (United States)

    Downs, G. S.; Krause-Polstorff, J.

    1986-01-01

    Previously published tables of geocentric arrival times for 24 pulsars covering a 12 year span are extended here to 14.5 years. The list of pulsars is extended by nine, most of which were observed for about 4 years. Known positins of these new objects are confirmed, and limits on the proper motions are obtained. Large phase excursions in PSR 0525 + 21 are found. The orbital parameters of the binary pulsar 0820 + 02 are tentatively confirmed. Short-term timing noise in excess of that expected from receiver considerations alone is established. Variations in the timing residuals for the original 24 pulsars are analyzed for correlations with other observable parameters. Little significant correlation with changes in pulse shape or energy or with the drift correction is found on time scales of 500 pulses or longer.

  14. An Eccentric Binary Millisecond Pulsar in the Galactic Plane

    CERN Document Server

    Champion, D J; Lazarus, P; Camilo, F; Bassa, C; Kaspi, V M; Nice, D J; Freire, P C C; Stairs, I H; Van Leeuwen, J; Stappers, B W; Cordes, J M; Hessels, J W T; Lorimer, D R; Arzoumanian, Z; Backer, D C; Bhat, N D R; Chatterjee, S; Cognard, I; Deneva, J S; Faucher-Giguere, C -A; Gaensler, B M; Han, J L; Jenet, F A; Kasian, L; Kondratiev, V I; Krämer, M; Lazio, J; McLaughlin, M A; Venkataraman, A; Vlemmings, W

    2008-01-01

    Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 ms in a highly eccentric (e = 0.44) 95-day orbit around a solar mass companion. Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars. Alternative formation scenarios involve recycling a neutron star in a globular cluster then ejecting it into the Galactic disk or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74+/-0.04 Msun, an unusually high value.

  15. Exploring Radio Pulsars With New Technologies

    Science.gov (United States)

    Torne, Pablo

    2017-04-01

    simultaneous observations): the Nançay 94-m equivalent, the Effelsberg 100-m, the IRAM 30-m, and the APEX 12-m radio telescopes, allowing us to cover a frequency range from 2.54 to 472 GHz. The observations at the short millimetre range made use of new broad-band instrumentation never before used for pulsar observations. These observations resulted in the detection of SGR J1745-2900 from 2.54 to 291 GHz, providing measurements of its variable flux density, its also-varying spectrum, and evidence for polarized millimetre emission. The detections above 144 GHz are the highest radio frequency detections of pulsed emission from neutron stars to date, results that set new constraints on the still poorly-understood radio emission mechanism of pulsars. Since the study of the properties of pulsar emission at very high radio frequencies is relevant for understanding the radio emission process, further observations of a sample of six normal pulsars between 87 and 154 GHz were carried out using the IRAM 30-m. The initial results of this ongoing project include the detections of PSR B0355+54 up to 138 GHz, together with flux density measurements. For the other five pulsars, no obvious detections were achieved. Above 87 GHz, our detections of PSR B0355+54 are the highest-frequency detections of emission from a normal pulsar in the radio band, showing that normal pulsars continue emitting in the short millimetre regime. We found no evidence of a flattening or turn-up in the spectrum, a feature that could provide information about the emission mechanism. The intensity of this pulsar apparently decreases at and above 87 GHz, but our results suffer from uncertainties in the calibration and the possible intrinsic intensity variability of the pulsar. Forthcoming precise calibration information about the instrument will allow us to revisit the data providing stronger conclusions on the the nature of PSR B0355+54's apparent varying intensity at the millimetre wavelengths. In addition to the

  16. Multiwavelength monitoring and X-ray brightening of Be X-ray binary PSR J2032+4127/MT91 213 on its approach to periastron

    CERN Document Server

    Ho, Wynn C G; Lyne, Andrew G; Stappers, Ben W; Coe, Malcolm J; Halpern, Jules P; Johnson, Tyrel J; Steele, Iain A

    2016-01-01

    The radio and gamma-ray pulsar PSR J2032+4127 was recently found to be in a decades-long orbit with the Be star MT91 213, with the pulsar moving rapidly toward periastron. This binary shares many similar characteristics with the previously unique binary system PSR B1259-63/LS 2883. Here we describe radio, X-ray, and optical monitoring of PSR J2032+4127/MT91 213. Our extended orbital phase coverage in radio, supplemented with Fermi gamma-ray data, allows us to update and refine the orbital period to 45-50 yr and time of periastron passage to November 2017. We analyze archival and recent Chandra and Swift observations and show that PSR J2032+4127/MT91 213 is now brighter in X-rays by a factor of ~70 since 2002 and ~20 since 2010. While the pulsar is still far from periastron, this increase in X-rays is possibly due to collisions between pulsar and Be star winds. Optical observations of the Halpha emission line of the Be star suggest that the size of its circumstellar disk may be varying by ~2 over timescales as...

  17. X-Ray Spectra of Young Pulsars and Their Wind Nebulae: Dependence on Spin-Down Energy Loss Rate

    Science.gov (United States)

    Gotthelf, E. V.

    2003-01-01

    An observational model is presented for the spectra of young rotation-powered pulsars and their nebulae based on a study of nine bright Crab-like pulsar systems observed with the Chandra X-ray observatory. A significant correlation is discovered between the X-ray spectra of these pulsars and that of their associated pulsar wind nebulae, both of which are observed to be a function of the spin-down energy loss rate, E. The 2-10 keV spectra of these objects are well characterized by an absorbed power-law model with photon indices, Gamma, in the range of 0.6 < Gamma (sub PSR) < 2.1 and 1.3 < Gamma(sub PWN) < 2.3, for the pulsars and their nebulae, respectively. A linear regression fit relating these two sets of indexes yields Gamma(sub PWN) = 0.91 +/- 0.18 + (0.66 +/- 0.11) Gamma (sub PSR), with a correlation coefficient of r = 0.97. The spectra of these pulsars are found to steepen as Gamma = Gamma(sub max) + alpha E (exp -1/2), with Gamma(sub max) providing an observational limit on the spectral slopes of young rotation-powered pulsars. These results reveal basic properties of young pulsar systems, allow new observational constraints on models of pulsar wind emission, and provide a means of predicting the energetics of pulsars lacking detected pulsations.

  18. Eight gamma-ray pulsars discovered in blind frequency searches of Fermi LAT data

    CERN Document Server

    Parkinson, P M Saz; Ziegler, M; Ray, P S; Abdo, A A; Ballet, J; Baring, M G; Belfiore, A; Burnett, T H; Caliandro, G A; Camilo, F; Caraveo, P A; de Luca, A; Ferrara, E C; Freire, P C C; Grove, J E; Gwon, C; Harding, A K; Johnson, R P; Johnson, T J; Johnston, S; Keith, M; Kerr, M; Knödlseder, J; Makeev, A; Marelli, M; Michelson, P F; Parent, D; Ransom, S M; Reimer, O; Romani, R W; Smith, D A; Thompson, D J; Watters, K; Weltevrede, P; Wolff, M T; Wood, K S

    2010-01-01

    We report the discovery of eight gamma-ray pulsars in blind frequency searches using the LAT, onboard the Fermi Gamma-ray Space Telescope. Five of the eight pulsars are young (tau_c10^36 erg/s), and located within the Galactic plane (|b|<3 deg). The remaining three are older, less energetic, and located off the plane. Five pulsars are associated with sources included in the LAT bright gamma-ray source list, but only one, PSR J1413-6205, is clearly associated with an EGRET source. PSR J1023-5746 has the smallest characteristic age (tau_c=4.6 kyr) and is the most energetic (Edot=1.1E37 erg/s) of all gamma-ray pulsars discovered so far in blind searches. PSRs J1957+5033 and J2055+25 have the largest characteristic ages (tau_c~1 Myr) and are the least energetic (Edot~5E33 erg/s) of the newly-discovered pulsars. We present the timing models, light curves, and detailed spectral parameters of the new pulsars. We used recent XMM observations to identify the counterpart of PSR J2055+25 as XMMU J205549.4+253959. In ...

  19. Optical observations of PSR J2021+3651 in the Dragonfly Nebula with the GTC

    CERN Document Server

    Kirichenko, Aida; Shternin, Peter; Shibanov, Yuriy; Ryspaeva, Elizaveta; Zyuzin, Dima; Durant, Martin; Kargaltsev, Oleg; Pavlov, George; Cabrera-Lavers, Antonio

    2015-01-01

    PSR J2021+3651 is a 17 kyr old rotation powered pulsar detected in the radio, X-rays, and $\\gamma$-rays. It powers a torus-like pulsar wind nebula with jets, dubbed the Dragonfly, which is very similar to that of the Vela pulsar. The Dragonfly is likely associated with the extended TeV source VER J2019+368 and extended radio emission. We conducted first deep optical observations with the GTC in the Sloan $r'$ band to search for optical counterparts of the pulsar and its nebula. No counterparts were detected down to $r'\\gtrsim27.2$ and $\\gtrsim24.8$ for the point-like pulsar and the compact X-ray nebula, respectively. We also reanalyzed Chandra archival X-ray data taking into account an interstellar extinction--distance relation, constructed by us for the Dragonfly line of sight using the red-clump stars as standard candles. This allowed us to constrain the distance to the pulsar, $D=1.8^{+1.7}_{-1.4}$ kpc at 90% confidence. It is much smaller than the dispersion measure distance of $\\sim$12 kpc but compatible...

  20. On the Pulse Intensity Modulation of PSR B0823+26

    CERN Document Server

    Young, N J; Weltevrede, P; Lyne, A G; Kramer, M

    2012-01-01

    We investigate the radio emission behaviour of PSR B0823+26, a pulsar which is known to undergo pulse nulling, using an 153-d intensive sequence of observations. The pulsar is found to exhibit both short (~min) and unusually long-term (~hours or more) nulls, which not only suggest that the source possesses a distribution of nulling timescales, but that it may also provide a link between conventional nulling pulsars and longer-term intermittent pulsars. Despite seeing evidence for periodicities in the pulsar radio emission, we are uncertain whether they are intrinsic to the source, due to the influence of observation sampling on the periodicity analysis performed. Remarkably, we find evidence to suggest that the pulsar may undergo pre-ignition periods of 'emission flickering', that is rapid changes between radio-on (active) and -off (null) emission states, before transitioning to a steady radio-emitting phase. We find no direct evidence to indicate that the object exhibits any change in spin-down rate between ...

  1. The 3D Space and Spin Velocities of a Gamma-ray Pulsar

    Science.gov (United States)

    Romani, Roger W.

    2016-04-01

    PSR J2030+4415 is a LAT-discovered 0.5My-old gamma-ray pulsar with an X-ray synchrotron trail and a rare Halpha bowshock. We have obtained GMOS IFU spectroscopic imaging of this shell, and show a sweep through the remarkable Halpha structure, comparing with the high energy emission. These data provide a unique 3D map of the momentum distribution of the relativistic pulsar wind. This shows that the pulsar is moving nearly in the plane of the sky and that the pulsar wind has a polar component misaligned with the space velocity. The spin axis is shown to be inclined some 95degrees to the Earth line of sight, explaining why this is a radio-quiet, gamma-only pulsar. Intriguingly, the shell also shows multiple bubbles that suggest that the pulsar wind power has varied substantially over the past 500 years.

  2. X-ray Counterparts of Millisecond Pulsars in Globular Clusters

    CERN Document Server

    Becker, W; Prinz, T

    2010-01-01

    We have systematically studied the X-ray emission properties of globular cluster millisecond pulsars in order to evaluate their spectral properties and luminosities in a uniform way. Cross-correlating the radio timing positions of the cluster pulsars with the high resolution Chandra images revealed 31 X-ray counterparts identified in nine different globular cluster systems, including those in 47 Tuc. Timing analysis has been performed for all sources corresponding to the temporal resolution available in the archival Chandra data. Making use of unpublished data on M28, M4 and NGC 6752 allowed us to obtain further constraints for the millisecond pulsar counterparts located in these clusters. Counting rate and energy flux upper limits were computed for those 36 pulsars for which no X-ray counterparts could be detected. Comparing the X-ray and radio pulse profiles of PSR J1821-2452 in M28 and the 47 Tuc pulsars PSR J0024-7204D,O,R indicated some correspondence between both wavebands. The X-ray efficiency of the g...

  3. A millisecond pulsar in an extremely wide binary system

    CERN Document Server

    Bassa, C G; Stappers, B W; Tauris, T M; Wevers, T; Jonker, P G; Lentati, L; Verbiest, J P W; Desvignes, G; Graikou, E; Guillemot, L; Freire, P C C; Lazarus, P; Caballero, R N; Champion, D J; Cognard, I; Jessner, A; Jordan, C; Karuppusamy, R; Kramer, M; Lazaridis, K; Lee, K J; Liu, K; Lyne, A G; McKee, J; Oslowski, S; Perrodin, D; Sanidas, S; Shaifullah, G; Smits, R; Theureau, G; Tiburzi, C; Zhu, W W

    2016-01-01

    We report on 22 yrs of radio timing observations of the millisecond pulsar J1024$-$0719 by the telescopes participating in the European Pulsar Timing Array (EPTA). These observations reveal a significant second derivative of the pulsar spin frequency and confirm the discrepancy between the parallax and Shklovskii distances that has been reported earlier. We also present optical astrometry, photometry and spectroscopy of 2MASS J10243869$-$0719190. We find that it is a low-metallicity main-sequence star (K7V spectral type, $\\mathrm{[M/H]}=-1.0$, $T_\\mathrm{eff}=4050\\pm50$ K) and that its position, proper motion and distance are consistent with those of PSR J1024$-$0719. We conclude that PSR J1024$-$0719 and 2MASS J10243869$-$0719190 form a common proper motion pair and are gravitationally bound. The gravitational interaction between the main-sequence star and the pulsar accounts for the spin frequency derivatives, which in turn resolves the distance discrepancy. Our observations suggest that the pulsar and main...

  4. Astronomers Discover Fastest-Spinning Pulsar

    Science.gov (United States)

    2006-01-01

    Astronomers using the National Science Foundation's Robert C. Byrd Green Bank Telescope have discovered the fastest-spinning neutron star ever found, a 20-mile-diameter superdense pulsar whirling faster than the blades of a kitchen blender. Their work yields important new information about the nature of one of the most exotic forms of matter known in the Universe. Pulsar Graphic Pulsars Are Spinning Neutron Stars CREDIT: Bill Saxton, NRAO/AUI/NSF (Click on image for larger version) "We believe that the matter in neutron stars is denser than an atomic nucleus, but it is unclear by how much. Our observations of such a rapidly rotating star set a hard upper limit on its size, and hence on how dense the star can be.," said Jason Hessels, a graduate student at McGill University in Montreal. Hessels and his colleagues presented their findings to the American Astronomical Society's meeting in Washington, DC. Pulsars are spinning neutron stars that sling "lighthouse beams" of radio waves or light around as they spin. A neutron star is what is left after a massive star explodes at the end of its "normal" life. With no nuclear fuel left to produce energy to offset the stellar remnant's weight, its material is compressed to extreme densities. The pressure squeezes together most of its protons and electrons to form neutrons; hence, the name "neutron star." "Neutron stars are incredible laboratories for learning about the physics of the fundamental particles of nature, and this pulsar has given us an important new limit," explained Scott Ransom, an astronomer at the National Radio Astronomy Observatory and one of Hessels' collaborators on this work. The scientists discovered the pulsar, named PSR J1748-2446ad, in a globular cluster of stars called Terzan 5, located some 28,000 light-years from Earth in the constellation Sagittarius. The newly-discovered pulsar is spinning 716 times per second, or at 716 Hertz (Hz), readily beating the previous record of 642 Hz from a pulsar

  5. Low-Frequency Variability of - for Timing of Millisecond Pulsars

    Science.gov (United States)

    Blandford, R.; Narayan, R.

    Rickett, Coles and Bourgois (1984) have argued that long-term (months to years) variation in pulsar flux is caused by fluctuations in the interstellar electron density on length scales ≡1013-16cm. In this paper the authors show that there should then be correlated fluctuations in the pulse arrival time, pulse width, and angular size. PSR 1937+21 is suitable for detecting some of the new effects. The timing noise and pulse width variation in this pulsar is estimated assuming a power-law spectrum for the electron density fluctuations, normalized using scintillation data.

  6. A new nearby pulsar wind nebula overlapping the RX J0852.0-4622 supernova remnant

    CERN Document Server

    Acero, F; Ballet, J; Renaud, M; Terrier, R

    2012-01-01

    Energetic pulsars can be embedded in a nebula of relativistic leptons which is powered by the dissipation of the rotational energy of the pulsar. The object PSR J0855-4644 is an energetic and fast-spinning pulsar (Edot = 1.1x10^36 erg/s, P=65 ms) discovered near the South-East rim of the supernova remnant (SNR) RX J0852.0-4622 (aka Vela Jr) by the Parkes multibeam survey. The position of the pulsar is in spatial coincidence with an enhancement in X-rays and TeV gamma-rays, which could be due to its putative pulsar wind nebula (PWN). The purpose of this study is to search for diffuse non-thermal X-ray emission around PSR J0855-4644 to test for the presence of a PWN and to estimate the distance to the pulsar. An X-ray observation was carried out with the XMM-Newton satellite to constrain the properties of the pulsar and its nebula. The absorption column density derived in X-rays from the pulsar and from different regions of the rim of the SNR was compared with the absorption derived from the atomic (HI) and mol...

  7. Suzaku Observation of HESS J1825-137: Discovery of Largely-Extended X-rays near from PSR J1826-1334

    CERN Document Server

    Uchiyama, H; Tsuru, T G; Koyama, K; Bamba, A

    2008-01-01

    We observed the brightest part of HESS J1825-137 with the Suzaku XIS, and found diffuse X-rays extending at least up to 15' (~ 17 pc) from the pulsar PSR J1826-1334. The spectra have no emission line, and are fitted with an absorbed power-law model. The X-rays, therefore, are likely due to synchrotron emission from a pulsar wind nebula. The photon index near at the pulsar (r 8.8 times 10^3 km s^{-1}.

  8. The Deceptively Boring PSR J1738+0333

    CERN Document Server

    Freire, Paulo

    2010-01-01

    We present preliminary results of 7 years of Arecibo timing of the pulsar-white dwarf binary PSR J1738+0333. We can measure the proper motion, parallax with excellent precision and have detected the orbital decay. Furthermore, the companion has been detected at optical wavelengths and a mass ratio of 8.1 +/- 0.3 has been measured from the orbital variation of its Doppler shift. Once the companion mass is determined from the optical measurements, this system will provide strong limits for the radiation of dipolar gravitational waves. Assuming that general relativity holds, the fast-improving measurement of the orbital decay, combined with the measurement of the mass ratio, will provide an independent and precise measurement of the component masses.

  9. Resonance in PSR B1257+12 Planetary System

    CERN Document Server

    Konacki, M; Wolszczan, A; Konacki, Maciej; Maciejewski, Andrzej J.; Wolszczan, Alex

    1999-01-01

    In this paper we present a new method that can be used for analysis of time of arrival of a pulsar pulses (TOAs). It is designated especially to detect quasi-periodic variations of TOAs. We apply our method to timing observations of PSR B1257+12 and demonstrate that using it it is possible to detect not only first harmonics of a periodic variations, but also the presence of a resonance effect. The resonance effect detected, independently of its physical origin, can appear only when there is a non-linear interaction between two periodic modes. The explanation of TOAs variations as an effect of the existence of planets is, till now, the only known and well justified. In this context, the existence of the resonance frequency in TOAs is the most significant signature of the gravitational interaction of planets.

  10. A Detailed X-Ray Investigation of PSR J2021+4026 and the γ-Cygni Supernova Remnant

    Science.gov (United States)

    Hui, C. Y.; Seo, K. A.; Lin, L. C. C.; Huang, R. H. H.; Hu, C. P.; Wu, J. H. K.; Trepl, L.; Takata, J.; Wang, Y.; Chou, Y.; Cheng, K. S.; Kong, A. K. H.

    2015-01-01

    We have investigated the field around the radio-quiet γ-ray pulsar, PSR J2021+4026, with a ~140 ks XMM-Newton observation and ~56 ks archival Chandra data. Through analyzing the pulsed spectrum, we show that the X-ray pulsation is purely thermal in nature, which suggests that the pulsation originated from a hot polar cap with T ~ 3 × 106 K on the surface of a rotating neutron star. On the other hand, the power-law (PL) component that dominates the pulsar emission in the hard band is originated from off-pulse phases, which possibly comes from a pulsar wind nebula. In re-analyzing the Chandra data, we have confirmed the presence of a bow-shock nebula that extends from the pulsar to the west by ~10 arcsec. The orientation of this nebular feature suggests that the pulsar is probably moving eastward, which is consistent with the speculated proper motion by extrapolating from the nominal geometrical center of the supernova remnant (SNR) G78.2+2.1 to the current pulsar position. For G78.2+2.1, our deep XMM-Newton observation also enables a study of the central region and part of the southeastern region with superior photon statistics. The column absorption derived for the SNR is comparable to that for PSR J2021+4026, which supports their association. The remnant emission in both of the examined regions is in a non-equilibrium ionization state. Also, the elapsed time of both regions after shock-heating is apparently shorter than the Sedov age of G78.2+2.1. This might suggest that the reverse shock has reached the center not long ago. Apart from PSR J2021+4026 and G78.2+2.1, we have also serendipitously detected an X-ray flash-like event, XMM J202154.7+402855, from this XMM-Newton observation.

  11. XMM-Newton Observations of PSR B1706-44

    CERN Document Server

    McGowan, K E; Cropper, M; Kennea, J A; Cordova, F A; Ho, C; Sasseen, T; Vestrand, W T; Gowan, Katherine E. Mc; Zane, Silvia; Cropper, Mark; Kennea, Jamie A.; Cordova, France A.; Ho, Cheng; Sasseen, Tim

    2004-01-01

    We report on the XMM-Newton observations of the young, 102 ms pulsar PSR B1706-44. We have found that both a blackbody plus power-law and a magnetized atmospheric model plus power-law provide an excellent fit to the EPIC spectra. The two scenarios are therefore indistinguishable on a statistical basis, although we are inclined to prefer the latter on physical grounds. In this case, assuming a source distance of ~2.3 kpc, the size of the region responsible for the thermal emission is R~13 km, compatible with the surface of a neutron star. A comparison of the surface temperature of PSR B1706-44 obtained from this fit with cooling curves favor a medium mass neutron star with M~1.45 solar masses or M~1.59 solar masses, depending on two different models of proton superfluidity in the interior. The large collecting area of XMM-Newton allows us to resolve a substructure in the broad soft X-ray modulation detected by Chandra, revealing the presence of two separate peaks with pulsed fractions of 7 +/- 4% and 15 +/- 3%...

  12. Centrifugal acceleration of plasma in pulsar magnetosphere

    Indian Academy of Sciences (India)

    R T Gangadhara; V Krishna

    2003-12-01

    We present a relativistic model for the centrifugal acceleration of plasma bunches and the coherent radio emission in pulsar magnetosphere. We find that rotation broadens the width of leading component compared to the width of trailing component. We explain this difference in the component widths using the nested cone emission geometry. We estimate the effect of pulsar spin on the Stokes parameters, and find that the inclination between the rotation and magnetic axes can introduce an asymmetry in the circular polarization of the conal components. We analyse the single pulse polarization data of PSR B0329+54 at 606 MHz, and find that in its conal components, one sense of circular polarization dominates in the leading component while the other sense dominates in the trailing component. Our simulation shows that changing the sign of the impact parameter changes the sense of circular polarization as well as the swing of polarization angle.

  13. 50 pico arcsecond astrometry of pulsar emission

    CERN Document Server

    Pen, Ue-Li; Deller, Adam; Brisken, Walter

    2013-01-01

    We use VLBI imaging of the interstellar scattering speckle pattern associated with the pulsar PSR 0834+06 to measure the astrometric motion of its emission. The ~ 5AU interstellar baselines, provided by interference between speckles spanning the scattering disk, enable us to detect motions with sub nanoarcsecond accuracy. We measure a small pulse deflection of ~8+/-2 km (not including geometric uncertainties), which is 100 times smaller than the native resolution of this interstellar interferometer. This implies that the emission region is small, and at an altitude of a few hundred km, with the exact value depending on field geometry. This is substantially closer to the star than to the light cylinder. Future VLBI measurements can improve on this finding. This new regime of ultra-precise astrometry may enable precision parallax distance determination of pulsar binary displacements.

  14. Timing of Five PALFA-Discovered Millisecond Pulsars

    CERN Document Server

    Stovall, K; Bogdanov, S; Brazier, A; Camilo, F; Cardoso, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J S; Ferdman, R; Freire, P C C; Hessels, J W T; Jenet, F; Kaplan, D L; Karako-Argaman, C; Kaspi, V M; Knispel, B; Kotulla, R; Lazarus, P; Lee, K J; van Leeuwen, J; Lynch, R; Lyne, A G; Madsen, E; McLaughlin, M A; Patel, C; Ransom, S M; Scholz, P; Siemens, X; Stairs, I H; Stappers, B W; Swiggum, J; Zhu, W W; Venkataraman, A

    2016-01-01

    We report the discovery and timing results for five millisecond pulsars (MSPs) from the Arecibo PALFA survey: PSRs J1906+0055, J1914+0659, J1933+1726, J1938+2516, and J1957+2516. Timing observations of the 5 pulsars were conducted with the Arecibo and Lovell telescopes for time spans ranging from 1.5 to 3.3 yr. All of the MSPs except one (PSR J1914+0659) are in binary systems with low eccentricities. PSR J1957+2516 is likely a redback pulsar, with a ~0.1 $M_\\odot$ companion and possible eclipses that last ~10% of the orbit. The position of PSR J1957+2516 is also coincident with a NIR source. All 5 MSPs are distant (>3.1 kpc) as determined from their dispersion measures, and none of them show evidence of $\\gamma$-ray pulsations in a search of Fermi Gamma-Ray Space Telescope data. These 5 MSPs bring the total number of MSPs discovered by the PALFA survey to 26 and further demonstrate the power of this survey in finding distant, highly dispersed MSPs deep in the Galactic plane.

  15. A massive millisecond pulsar in an eccentric binary

    Science.gov (United States)

    Barr, E. D.; Freire, P. C. C.; Kramer, M.; Champion, D. J.; Berezina, M.; Bassa, C. G.; Lyne, A. G.; Stappers, B. W.

    2017-02-01

    The recent discovery of a population of eccentric (e ˜ 0.1) millisecond pulsar (MSP) binaries with low-mass white dwarf companions in the Galactic field represents a challenge to evolutionary models that explain MSP formation as recycling: All such models predict that the orbits become highly circularized during a long period of accretion. The members of this new population exhibit remarkably similar properties (orbital periods, eccentricities, companion masses, spin periods), and several models have been put forward that suggest a common formation channel. In this work, we present the results of an extensive timing campaign focusing on one member of this new population, PSR J1946+3417. Through the measurement of both the advance of periastron and the Shapiro delay for this system, we determine the mass of the pulsar, mass of the companion and the inclination of the orbit to be 1.828(22) M⊙, 0.2656(19) M⊙ and 76.4 ± 0.6 degrees, respectively, under the assumption that general relativity is the true description of gravity. Notably, this is the third highest mass measured for any pulsar. Using these masses and the astrometric properties of PSR J1946+3417, we examine three proposed formation channels for eccentric MSP binaries. While our results are consistent with circumbinary disc-driven eccentricity growth or neutron star to strange star phase transition, we rule out rotationally delayed accretion-induced collapse as the mechanism responsible for the configuration of the PSR J1946+3417 system.

  16. Eight New Millisecond Pulsars in NGC 6440 and NGC 6441

    CERN Document Server

    Freire, Paulo C C; Begin, Steve; Stairs, Ingrid H; Hessels, Jason W T; Frey, Lucille H; Camilo, Fernando

    2007-01-01

    Motivated by the recent discovery of 30 new millisecond pulsars in Terzan 5, made using the Green Bank Telescope's S-band receiver and the Pulsar Spigot spectrometer, we have set out to use the same observing system in a systematic search for pulsars in other globular clusters. Here we report on the discovery of five new pulsars in NGC 6440 and three in NGC 6441; each cluster previously had one known pulsar. Using the most recent distance estimates to these clusters, we conclude that there are as many potentially observable pulsars in NGC 6440 and NGC 6441 as in Terzan 5. We present timing solutions for all of the pulsars in these globular clusters. Four of the new discoveries are in binary systems; one of them, PSR J1748-2021B (NGC 6440B), has a wide (P_b = 20.5 d) and eccentric (e = 0.57) orbit. This allowed a measurement of its rate of advance of periastron: 0.00391(18) degrees per year. If due to the effects of general relativity, the total mass of this binary system is 2.92 +/- 0.20 solar masses (1 sigma...

  17. Timing of 29 Pulsars Discovered in the PALFA Survey

    Science.gov (United States)

    Lyne, A. G.; Stappers, B. W.; Bogdanov, S.; Ferdman, R. D.; Freire, P. C. C.; Kaspi, V. M.; Knispel, B.; Lynch, R.; Allen, B.; Brazier, A.; Camilo, F.; Cardoso, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J. S.; Hessels, J. W. T.; Jenet, F. A.; Lazarus, P.; van Leeuwen, J.; Lorimer, D. R.; Madsen, E.; McKee, J.; McLaughlin, M. A.; Parent, E.; Patel, C.; Ransom, S. M.; Scholz, P.; Seymour, A.; Siemens, X.; Spitler, L. G.; Stairs, I. H.; Stovall, K.; Swiggum, J.; Wharton, R. S.; Zhu, W. W.; Aulbert, C.; Bock, O.; Eggenstein, H.-B.; Fehrmann, H.; Machenschalk, B.

    2017-01-01

    We report on the discovery and timing observations of 29 distant long-period pulsars found in the ongoing Arecibo L-band Feed Array pulsar survey. Following discovery with the Arecibo Telescope, confirmation and timing observations of these pulsars over several years at Jodrell Bank Observatory have yielded high-precision positions and measurements of rotation and radiation properties. We have used multi-frequency data to measure the interstellar scattering properties of some of these pulsars. Most of the pulsars have properties that mirror those of the previously known pulsar population, although four show some notable characteristics. PSRs J1907+0631 and J1925+1720 are young and are associated with supernova remnants or plerionic nebulae: J1907+0631 lies close to the center of SNR G40.5‑0.5, while J1925+1720 is coincident with a high-energy Fermi γ-ray source. One pulsar, J1932+1500, is in a surprisingly eccentric, 199 day binary orbit with a companion having a minimum mass of 0.33 M⊙. Several of the sources exhibit timing noise, and two, PSRs J0611+1436 and J1907+0631, have both suffered large glitches, but with very different post-glitch rotation properties. In particular, the rotational period of PSR J0611+1436 will not recover to its pre-glitch value for about 12 years, a far greater recovery timescale than seen following any other large glitches.

  18. Tachyonic quantum densities of relativistic electron plasmas: Cherenkov spectra of γ-ray pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Tomaschitz, Roman, E-mail: tom@geminga.org

    2014-06-27

    Tachyonic Cherenkov radiation in second quantization can explain the subexponential spectral tails of GeV γ-ray pulsars (Crab pulsar, PSR J1836+5925, PSR J0007+7303, PSR J2021+4026) recently observed with the Fermi-LAT, VERITAS and MAGIC telescopes. The radiation is emitted by a thermal ultra-relativistic electron plasma. The Cherenkov effect is derived from a Maxwell–Proca field with negative mass-square in a dispersive spacetime. The frequency variation of the tachyon mass results in exp(−β{sup ^}ω{sup 1−ρ}) attenuation of the asymptotic Cherenkov energy flux, where β{sup ^} is a decay constant related to the electron temperature and ρ is the frequency scaling exponent of the tachyon mass. An exponent in the range 0<ρ<1 can reproduce the observed subexponential decay of the energy flux. For the Crab pulsar, we find ρ=0.81±0.02, inferred from the substantially weaker-than-exponential decay of its spectral tail measured by MAGIC over an extended energy range. The scaling exponent ρ determines whether the group velocity of the tachyonic γ-rays is sub- or superluminal. - Highlights: • Quantized tachyonic Cherenkov densities lead to subexponential spectral decay. • γ-Ray spectral fits to Crab pulsar, PSR J1836+5925, PSR J0007+7303, PSR J2021+4026. • The polarization of γ-rays is analyzed in the quasiclassical regime and quantum limit. • Three degrees of polarization due to the negative mass-square of the Maxwell–Proca field. • Weibull decay of spectral tails caused by frequency scaling of the tachyon mass.

  19. Timing analysis for 20 millisecond pulsars in the Parkes Pulsar Timing Array

    CERN Document Server

    Reardon, D J; Coles, W; Levin, Y; Keith, M J; Bailes, M; Bhat, N D R; Burke-Spolaor, S; Dai, S; Kerr, M; Lasky, P D; Manchester, R N; Osłowski, S; Ravi, V; Shannon, R M; van Straten, W; Toomey, L; Wang, J; Wen, L; You, X P; Zhu, X -J

    2015-01-01

    We present timing models for 20 millisecond pulsars in the Parkes Pulsar Timing Array. The precision of the parameter measurements in these models has been improved over earlier results by using longer data sets and modelling the non-stationary noise. We describe a new noise modelling procedure and demonstrate its effectiveness using simulated data. Our methodology includes the addition of annual dispersion measure (DM) variations to the timing models of some pulsars. We present the first significant parallax measurements for PSRs J1024-0719, J1045-4509, J1600-3053, J1603-7202, and J1730-2304, as well as the first significant measurements of some post-Keplerian orbital parameters in six binary pulsars, caused by kinematic effects. Improved Shapiro delay measurements have resulted in much improved pulsar mass measurements, particularly for PSRs J0437-4715 and J1909-3744 with $M_p=1.44\\pm0.07$ $M_\\odot$ and $M_p=1.47\\pm0.03$ $M_\\odot$ respectively. The improved orbital period-derivative measurement for PSR J043...

  20. THE TALE OF THE TWO TAILS OF THE OLDISH PSR J2055+2539

    Energy Technology Data Exchange (ETDEWEB)

    Marelli, Martino; Pizzocaro, Daniele; Luca, Andrea De; Gastaldello, Fabio; Caraveo, Patrizia [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133 Milano (Italy); Parkinson, Pablo Saz [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong)

    2016-03-01

    We analyzed a deep XMM-Newton observation of the radio-quiet γ-ray PSR J2055+2539. The spectrum of the X-ray counterpart is nonthermal, with a photon index of Γ = 2.36 ± 0.14 (1σ confidence). We detected X-ray pulsations with a pulsed fraction of 25% ± 3% and a sinusoidal shape. Taking into account considerations on the γ-ray efficiency of the pulsar and on its X-ray spectrum, we can infer a pulsar distance ranging from 450 to 750 pc. We found two different nebular features associated with PSR J2055+2539 and protruding from it. The angle between the two nebular main axes is ∼162.°8 ± 0.°7. The main, brighter feature is 12′ long and <20″ thick, characterized by an asymmetry with respect to the main axis that evolves with the distance from the pulsar, possibly forming a helical pattern. The secondary feature is 250″ × 30″. Both nebulae present an almost flat brightness profile with a sudden decrease at the end. The nebulae can be fitted by either a power-law model or a thermal bremsstrahlung model. A plausible interpretation of the brighter nebula is in terms of a collimated ballistic jet. The secondary nebula is most likely a classical synchrotron-emitting tail.

  1. The tale of the two tails of the oldish PSR J2055+2539

    CERN Document Server

    Marelli, Martino; De Luca, Andrea; Gastaldello, Fabio; Caraveo, Patrizia; Parkinson, Pablo Saz

    2015-01-01

    We analyzed a deep XMM-Newton observations of the radio-quiet gamma-ray PSR J2055+2539. The spectrum of the X-ray counterpart is non-thermal, with a photon index of 2.36$\\pm$0.14 (1$\\sigma$ confidence). We detected X-ray pulsations with a pulsed fraction of (25$\\pm$3)% and a sinusoidal shape. Taking into account considerations on the gamma-ray efficiency of the pulsar and on its X-ray spectrum, we can infer a pulsar distance ranging from 450 pc to 750 pc. We found two different nebular features associated to PSR J2055+2539 and protruding from it. The angle between the two nebular main axes is $\\sim$ (162.8$\\pm$0.7) degrees. The main, brighter feature is 12'-long and <20"-thick, characterized by an asymmetry with respect to the main axis that evolves with the distance from the pulsar, possibly forming a helical pattern. The secondary feature is 250" x 30". Both nebulae present an almost flat brightness profile with a sudden decrease at the end. The nebulae can be fitted either by a power-law model or a ther...

  2. Improving Pulsar Timing Precision with Single Pulses

    CERN Document Server

    Kerr, Matthew

    2015-01-01

    The measurement error of pulse times of arrival (TOAs) in the high S/N limit is dominated by the quasi-random variation of a pulsar's emission profile from rotation to rotation. Like measurement noise, this noise is only reduced as the square root of observing time, posing a major challenge to future pulsar timing campaigns with large aperture telescopes, e.g. the Five-hundred-metre Aperture Spherical Telescope and the Square Kilometre Array. We propose a new method of pulsar timing that attempts to approximate the pulse-to-pulse variability with a small family of 'basis' pulses. If pulsar data are integrated over many rotations, this basis can be used to measure sub-pulse structure. Or, if high-time resolution data are available, the basis can be used to 'tag' single pulses and produce an optimal timing template. With realistic simulations, we show that these applications can dramatically reduce the effect of pulse-to-pulse variability on TOAs. Using high-time resolution data taken from the bright PSR J0835-...

  3. Pulsar Wind Nebula candidates recently discovered by H.E.S.S

    CERN Document Server

    Renaud, M; Komin, N; Moulin, E; Marandon, V; Clapson, A -C

    2008-01-01

    H.E.S.S. is currently the most sensitive instrument in the very-high-energy gamma-ray domain and has revealed many new sources along the Galactic Plane, a significant fraction of which seems to be associated with energetic pulsars. HESS J1825-137 and Vela X are considered to be the prototypes of such sources in which the large VHE nebula results from the whole history of the pulsar wind and the supernova remnant host, both evolving in a complex interstellar medium. These nebulae are seen to be offset from the pulsar position and, for HESS J1825-137, a spectral steepening at increasing distance from the pulsar has been measured. In this context, updated H.E.S.S. results on two previously published sources, namely HESS J1809-193 and HESS J1912+101, and preliminary results on the newly discovered HESS J1356-645, are presented. These extended VHE sources are thought to be associated with the energetic pulsars PSR J1809-1917, PSR J1913+1011 and PSR J1357-6429, respectively. Properties of each source in the VHE reg...

  4. "Magnetar-like Emission from the Young Pulsar in Kes 75"

    Science.gov (United States)

    Gavrill, R.; Gonzalez, M.; Livingstone, M.; Gotthelf, E.; Kaspi, V.; Woods, P.

    2008-01-01

    Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs) are thought to be magnetars - isolated neutron stars with ultra-high magnetic fields. These sources exhibit X-ray and gamma-ray bursts, and week to month-long flux enhancements, all too bright to be accounted for by their spindown luminosity. A mystery in neutron star astrophysics is why such emission has never been seen from rotation-powered pulsars with magnetar-like fields. Here we report the first detection of magnetar-like X-ray bursts from what has been long thought to be a rotation-powered pulsar, PSR 51846-0258, at the center of the supernova remnant Kes 75. PSR J1846-0258 has an inferred surface dipolar magnetic field of 4.9 X 1103 G, which is sixth highest among the > 1700 known rotation-powered pulsars, but less than those of the approximately 12 confirmed magnetars. The bursts coincided with a sudden flux increase and an unprecedented change in timing behavior, f m l y establishing PSR 51 846-0258 as a rotation-powered pulsar/magnetar transition object. These observations demonstrate that magnetar-like emission can be seen from sources with fields lower than the magnetars, and suggest that the intensity of magnetar-like activity in neutron stars depends on magnetic field strength in a more continuous way than previously thought.

  5. Searching for pulsars associated with the Fermi GeV excess

    Science.gov (United States)

    Bhakta, D.; Deneva, J. S.; Frail, D. A.; de Gasperin, F.; Intema, H. T.; Jagannathan, P.; Mooley, K. P.

    2017-07-01

    The Fermi Large Area Telescope has detected an extended region of GeV emission towards the Galactic Centre that is currently thought to be powered by dark matter annihilation or a population of young and/or millisecond pulsars. In a test of the pulsar hypothesis, we have carried out an initial search of a 20 deg2 area centred on the peak of the galactic centre GeV excess. Candidate pulsars were identified as a compact, steep spectrum continuum radio source on interferometric images and followed with targeted single-dish pulsation searches. We report the discovery of the recycled pulsar PSR 1751-2737 with a spin period of 2.23 ms. PSR 1751-2737 appears to be an isolated recycled pulsar located within the disc of our Galaxy, and it is not part of the putative bulge population of pulsars that are thought to be responsible for the excess GeV emission. However, our initial success in this small pilot survey suggests that this hybrid method (i.e. wide-field interferometric imaging followed up with single-dish pulsation searches) may be an efficient alternative strategy for testing whether a putative bulge population of pulsars is responsible for the GeV excess.

  6. Multi-wavelength observations of PSR B1259-63 during the 2014 periastron passage

    Science.gov (United States)

    van Soelen, B.; Armstrong, R. P.; Väisänen, P.; Sushch, I.; Odendaal, A.; Meintjes, P. J.

    The gamma-ray binary star system PSR B1259-63 is unique among the five known systems since it is the only one where a radio pulsar has been directly detected. Close to periastron the system produces non-thermal/unpulsed emission from radio to TeV gamma-ray energies. In 2010 Fermi/LAT detected a rapid increase and peak emission at ˜30 days after periastron, at a time when emission at other wavelengths was already decreasing. PSR B1259-63 will go through periastron again on 2014 May 4. We have proposed to use the Southern African Large Telescope and the KAT-7 radio telescope array in order to contribute to the multi-wavelength coverage of the system. An outline of this proposed multi-wavelength campaign is presented.

  7. What caused the GeV flare of PSR B1259-63 ?

    CERN Document Server

    Dubus, G

    2013-01-01

    PSR B1259-63 is a gamma-ray binary system composed of a high spindown pulsar and a massive star. Non-thermal emission up to TeV energies is observed near periastron passage, attributed to emission from high energy e+e- pairs accelerated at the shock with the circumstellar material from the companion star, resulting in a small-scale pulsar wind nebula. Weak gamma-ray emission was detected by the Fermi/LAT at the last periastron passage, unexpectedly followed 30 days later by a strong flare, limited to the GeV band, during which the luminosity nearly reached the spindown power of the pulsar. The origin of this GeV flare remains mysterious. We investigate whether the flare could have been caused by pairs, located in the vicinity of the pulsar, up-scattering X-ray photons from the surrounding pulsar wind nebula rather than UV stellar photons, as usually assumed. Such a model is suggested by the geometry of the interaction region at the time of the flare. We compute the gamma-ray lightcurve for this scenario, base...

  8. Rings and Jets around PSR J2021+3651: the `Dragonfly Nebula'

    CERN Document Server

    Van Etten, Adam; Ng, C -Y

    2008-01-01

    We describe recent Chandra ACIS observations of the Vela-like pulsar PSR J2021+3651 and its pulsar wind nebula (PWN). This `Dragonfly Nebula' displays an axisymmetric morphology, with bright inner jets, a double-ridged inner nebula, and a ~30" polar jet. The PWN is embedded in faint diffuse emission: a bow shock-like structure with standoff ~1' brackets the pulsar to the east and emission trails off westward for 3-4'. Thermal (kT=0.16 +/-0.02 keV) and power law emission are detected from the pulsar. The nebular X-rays show spectral steepening from Gamma=1.5 in the equatorial torus to Gamma=1.9 in the outer nebula, suggesting synchrotron burn-off. A fit to the `Dragonfly' structure suggests a large (86 +/-1 degree) inclination with a double equatorial torus. Vela is currently the only other PWN showing such double structure. The >12 kpc distance implied by the pulsar dispersion measure is not supported by the X-ray data; spectral, scale and efficiency arguments suggest a more modest 3-4 kpc.

  9. 21-year timing of the black-widow pulsar J2051-0827

    CERN Document Server

    Shaifullah, G; Freire, P C C; Tauris, T M; Wex, N; Osłowski, S; Stappers, B W; Bassa, C G; Caballero, R N; Champion, D J; Cognard, I; Desvignes, G; Graikou, E; Guillemot, L; Janssen, G H; Jessner, A; Jordan, C; Karuppusamy, R; Kramer, M; Lazaridis, K; Lazarus, P; Lyne, A G; McKee, J W; Perrodin, D; Possenti, A; Tiburzi, C

    2016-01-01

    Timing results for the black-widow pulsar J2051-0827 are presented, using a 21-year dataset from four European Pulsar Timing Array telescopes and the Parkes radio telescope. This dataset, which is the longest published to date for a black-widow system, allows for an improved analysis that addresses previously unknown biases. While secular variations, as identified in previous analyses, are recovered, short-term variations are detected for the first time. Concurrently, a significant decrease of approx. 2.5x10-3 cm-3 pc in the dispersion measure associated with PSR J2051-0827 is measured for the first time and improvements are also made to estimates of the proper motion. Finally, PSR J2051-0827 is shown to have entered a relatively stable state suggesting the possibility of its eventual inclusion in pulsar timing arrays.

  10. X-Ray Pulsar Profile Recovery Based on Tracking-Differentiator

    Directory of Open Access Journals (Sweden)

    Dapeng Zhang

    2016-01-01

    Full Text Available The profile recovery is an important work in X-ray pulsar-based navigation. It is a key step for the analysis on the pulsar signal’s characteristic and the computing of time of arrival (TOA. This paper makes an argument for an algorithm based on the tracking-differentiator (TD to recover the profile from the low Signal-to-Noise Ratio (SNR signals. In the method, a TD filter with cascade structure is designed which has very low phase delay and amplitude distortion. In the simulation experiment, two typical pulsars (PSR B0531+21 and PSR B1937+21 are used to verify the algorithm’s performance. The simulation results show that the method satisfies the application requirements in the aspects of SNR and profile fidelity. By processing the data collected by the Rossi X-Ray Timing Explorer (RXTE satellite in space, similar results can also be achieved.

  11. 21 year timing of the black-widow pulsar J2051-0827

    Science.gov (United States)

    Shaifullah, G.; Verbiest, J. P. W.; Freire, P. C. C.; Tauris, T. M.; Wex, N.; Osłowski, S.; Stappers, B. W.; Bassa, C. G.; Caballero, R. N.; Champion, D. J.; Cognard, I.; Desvignes, G.; Graikou, E.; Guillemot, L.; Janssen, G. H.; Jessner, A.; Jordan, C.; Karuppusamy, R.; Kramer, M.; Lazaridis, K.; Lazarus, P.; Lyne, A. G.; McKee, J. W.; Perrodin, D.; Possenti, A.; Tiburzi, C.

    2016-10-01

    Timing results for the black-widow pulsar J2051-0827 are presented, using a 21 year data set from four European Pulsar Timing Array telescopes and the Parkes radio telescope. This data set, which is the longest published to date for a black-widow system, allows for an improved analysis that addresses previously unknown biases. While secular variations, as identified in previous analyses, are recovered, short-term variations are detected for the first time. Concurrently, a significant decrease of ˜ 2.5 × 10- 3 cm- 3 pc in the dispersion measure associated with PSR J2051-0827 is measured for the first time and improvements are also made to estimates of the proper motion. Finally, PSR J2051-0827 is shown to have entered a relatively stable state suggesting the possibility of its eventual inclusion in pulsar timing arrays.

  12. Observations and modeling of the companions of short period binary millisecond pulsars: evidence for high-mass neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Joshua; Halpern, Jules [Department of Astronomy, Columbia University, Mail Code 5246, 550 West 120th Street, New York, NY 10027 (United States)

    2014-10-01

    We present observations of fields containing eight recently discovered binary millisecond pulsars using the telescopes at MDM Observatory. Optical counterparts to four of these systems are detected, one of which, PSR J2214+3000, is a novel detection. Additionally, we present the fully phase-resolved B, V, and R light curves of the optical counterparts to two objects, PSR J1810+1744 and PSR J2215+5135 for which we employ model fitting using the eclipsing light curve (ELC) model of Orosz and Hauschildt to measure the unknown system parameters. For PSR J1810+1744, we find that the system parameters cannot be fit even assuming that 100% of the spin-down luminosity of the pulsar is irradiating the secondary, and so radial velocity measurements of this object will be required for the complete solution. However, PSR J2215+5135 exhibits light curves that are extremely well constrained using the ELC model and we find that the mass of the neutron star is constrained by these and the radio observations to be M {sub NS} > 1.75 M {sub ☉} at the 3σ level. We also find a discrepancy between the model temperature and the measured colors of this object, which we interpret as possible evidence for an additional high-temperature source such as a quiescent disk. Given this and the fact that PSR J2215+5135 contains a relatively high mass companion (M {sub c} > 0.1 M {sub ☉}), we propose that similar to the binary pulsar systems PSR J1023+0038 and IGR J18245–2452, the pulsar may transition between accretion- and rotation-powered modes.

  13. Pulsar population synthesis using palfa detections and pulsar search collaboratory discoveries including a wide DNS system and a nearby MSP

    Science.gov (United States)

    Swiggum, Joseph Karl

    students in the pulsar discovery process -- hands-on, cutting-edge research -- to foster their interest in pursuing Science, Technology, Engineering and Mathematics (STEM) related career paths. The PSC began in 2008; since then, over 100 teachers and 2,500 students from 18 states have participated and discovered seven pulsars. Of these seven, J1400--1431, a bright, nearby MSP shows promising characteristics for inclusion in pulsar timing arrays, which aim to detect gravitational waves by precisely timing an array of MSPs. Two others -- J1821+0155, a disrupted recycled pulsar and J1930--1852 show interesting properties due to interactions with binary companions. PSR J1930--1852 is a partially-recycled, first-to-evolve pulsar in a double neutron star (DNS) system with a high-eccentricity 45 day orbit. Its spin period and orbital period are factors of 2 and 3 higher, respectively, than any previously-known, primary DNS pulsars. We measure the relativistic advance of periastron o=0.00078(4), implying a total system mass of Mtot =2.59(4), which is consistent with other DNS systems. PSR J1930--1852's spin and orbital parameters, however, challenge current DNS evolution models, making it an important system for further investigation.

  14. Discovery of Nine Gamma-Ray Pulsars in Fermi-Lat Data Using a New Blind Search Method

    Science.gov (United States)

    Celik-Tinmaz, Ozlem; Ferrara, E. C.; Pletsch, H. J.; Allen, B.; Aulbert, C.; Fehrmann, H.; Kramer, M.; Barr, E. D.; Champion, D. J.; Eatough, R. P.; Freire, P. C. C.; Reich, W.; Lyne, A. G.; Ray, P. S.

    2011-01-01

    We report the discovery of nine previously unknown gamma-ray pulsars in a blind search of data from the Fermi Large Area Telescope (LAT). The pulsars were found with a novel hierarchical search method originally developed for detecting continuous gravitational waves from rapidly rotating neutron stars. Designed to find isolated pulsars spinning at up to kHz frequencies, the new method is computationally efficient, and incorporates several advances, including a metric-based gridding of the search parameter space (frequency, frequency derivative and sky location) and the use of photon probability weights. The nine pulsars have spin frequencies between 3 and 12 Hz, and characteristic ages ranging from 17 kyr to 3 Myr. Two of them, PSRs Jl803-2149 and J2111+4606, are young and energetic Galactic-plane pulsars (spin-down power above 6 x 10(exp 35) ergs per second and ages below 100 kyr). The seven remaining pulsars, PSRs J0106+4855, J010622+3749, Jl620-4927, Jl746-3239, J2028+3332,J2030+4415, J2139+4716, are older and less energetic; two of them are located at higher Galactic latitudes (|b| greater than 10 degrees). PSR J0106+4855 has the largest characteristic age (3 Myr) and the smallest surface magnetic field (2x 10(exp 11)G) of all LAT blind-search pulsars. PSR J2139+4716 has the lowest spin-down power (3 x l0(exp 33) erg per second) among all non-recycled gamma-ray pulsars ever found. Despite extensive multi-frequency observations, only PSR J0106+4855 has detectable pulsations in the radio band. The other eight pulsars belong to the increasing population of radio-quiet gamma-ray pulsars.

  15. Upper limits on gravitational wave emission from 78 radio pulsars

    Science.gov (United States)

    Abbott, B.; Abbott, R.; Adhikari, R.; Agresti, J.; Ajith, P.; Allen, B.; Amin, R.; Anderson, S. B.; Anderson, W. G.; Arain, M.; Araya, M.; Armandula, H.; Ashley, M.; Aston, S.; Aufmuth, P.; Aulbert, C.; Babak, S.; Ballmer, S.; Bantilan, H.; Barish, B. C.; Barker, C.; Barker, D.; Barr, B.; Barriga, P.; Barton, M. A.; Bayer, K.; Belczynski, K.; Betzwieser, J.; Beyersdorf, P. T.; Bhawal, B.; Bilenko, I. A.; Billingsley, G.; Biswas, R.; Black, E.; Blackburn, K.; Blackburn, L.; Blair, D.; Bland, B.; Bogenstahl, J.; Bogue, L.; Bork, R.; Boschi, V.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Brinkmann, M.; Brooks, A.; Brown, D. A.; Bullington, A.; Bunkowski, A.; Buonanno, A.; Burmeister, O.; Busby, D.; Butler, W. E.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cannizzo, J.; Cannon, K.; Cantley, C. A.; Cao, J.; Cardenas, L.; Carter, K.; Casey, M. M.; Castaldi, G.; Cepeda, C.; Chalkey, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Chiadini, F.; Chin, D.; Chin, E.; Chow, J.; Christensen, N.; Clark, J.; Cochrane, P.; Cokelaer, T.; Colacino, C. N.; Coldwell, R.; Conte, R.; Cook, D.; Corbitt, T.; Coward, D.; Coyne, D.; Creighton, J. D. E.; Creighton, T. D.; Croce, R. P.; Crooks, D. R. M.; Cruise, A. M.; Cumming, A.; Dalrymple, J.; D'Ambrosio, E.; Danzmann, K.; Davies, G.; Debra, D.; Degallaix, J.; Degree, M.; Demma, T.; Dergachev, V.; Desai, S.; Desalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; di Credico, A.; Diederichs, G.; Dietz, A.; Doomes, E. E.; Drever, R. W. P.; Dumas, J.-C.; Dupuis, R. J.; Dwyer, J. G.; Ehrens, P.; Espinoza, E.; Etzel, T.; Evans, M.; Evans, T.; Fairhurst, S.; Fan, Y.; Fazi, D.; Fejer, M. M.; Finn, L. S.; Fiumara, V.; Fotopoulos, N.; Franzen, A.; Franzen, K. Y.; Freise, A.; Frey, R.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Galdi, V.; Ganezer, K. S.; Garofoli, J.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Goda, K.; Goetz, E.; Goggin, L.; González, G.; Gossler, S.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, J.; Gretarsson, A. M.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, R.; Hage, B.; Hammer, D.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G.; Harstad, E.; Hayler, T.; Heefner, J.; Heng, I. S.; Heptonstall, A.; Heurs, M.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hosken, D.; Hough, J.; Howell, E.; Hoyland, D.; Huttner, S. H.; Ingram, D.; Innerhofer, E.; Ito, M.; Itoh, Y.; Ivanov, A.; Jackrel, D.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalili, F. Ya.; Kim, C.; King, P.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R. K.; Kozak, D.; Krishnan, B.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lazzarini, A.; Lee, B.; Lei, M.; Leiner, J.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Lindquist, P.; Lockerbie, N. A.; Longo, M.; Lormand, M.; Lubiński, M.; Lück, H.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Malec, M.; Mandic, V.; Marano, S.; Márka, S.; Markowitz, J.; Maros, E.; Martin, I.; Marx, J. N.; Mason, K.; Matone, L.; Matta, V.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McKenzie, K.; McNabb, J. W. C.; McWilliams, S.; Meier, T.; Melissinos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messaritaki, E.; Messenger, C. J.; Meyers, D.; Mikhailov, E.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Mohanty, S.; Moreno, G.; Mossavi, K.; Mowlowry, C.; Moylan, A.; Mudge, D.; Mueller, G.; Mukherjee, S.; Müller-Ebhardt, H.; Munch, J.; Murray, P.; Myers, E.; Myers, J.; Nash, T.; Newton, G.; Nishizawa, A.; Nocera, F.; Numata, K.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pan, Y.; Papa, M. A.; Parameshwaraiah, V.; Parameswariah, C.; Patel, P.; Pedraza, M.; Penn, S.; Pierro, V.; Pinto, I. M.; Pitkin, M.; Pletsch, H.; Plissi, M. V.; Postiglione, F.; Prix, R.; Quetschke, V.; Raab, F.; Rabeling, D.; Radkins, H.; Rahkola, R.; Rainer, N.; Rakhmanov, M.; Rawlins, K.; Ray-Majumder, S.; Re, V.; Regimbau, T.; Rehbein, H.; Reid, S.; Reitze, D. H.; Ribichini, L.; Riesen, R.; Riles, K.; Rivera, B.; Robertson, N. A.; Robinson, C.; Robinson, E. L.; Roddy, S.; Rodriguez, A.; Rogan, A. M.; Rollins, J.; Romano, J. D.; Romie, J.; Route, R.; Rowan, S.; Rüdiger, A.; Ruet, L.; Russell, P.; Ryan, K.; Sakata, S.; Samidi, M.; de La Jordana, L. Sancho; Sandberg, V.; Sanders, G. H.; Sannibale, V.; Saraf, S.; Sarin, P.; Sathyaprakash, B. S.; Sato, S.; Saulson, P. R.; Savage, R.; Savov, P.; Sazonov, A.; Schediwy, S.; Schilling, R.; Schnabel, R.; Schofield, R.; Schutz, B. F.; Schwinberg, P.; Scott, S. M.; Searle, A. C.; Sears, B.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Shawhan, P.; Shoemaker, D. H.; Sibley, A.; Sidles, J. A.; Siemens, X.; Sigg, D.; Sinha, S.; Sintes, A. M.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Somiya, K.; Strain, K. A.; Strom, D. M.; Stuver, A.; Summerscales, T. Z.; Sun, K.-X.; Sung, M.; Sutton, P. J.; Takahashi, H.; Tanner, D. B.; Tarallo, M.; Taylor, R.; Taylor, R.; Thacker, J.; Thorne, K. A.; Thorne, K. S.; Thüring, A.; Tokmakov, K. V.; Torres, C.; Torrie, C.; Traylor, G.; Trias, M.; Tyler, W.; Ugolini, D.; Ungarelli, C.; Urbanek, K.; Vahlbruch, H.; Vallisneri, M.; van den Broeck, C.; van Putten, M.; Varvella, M.; Vass, S.; Vecchio, A.; Veitch, J.; Veitch, P.; Villar, A.; Vorvick, C.; Vyachanin, S. P.; Waldman, S. J.; Wallace, L.; Ward, H.; Ward, R.; Watts, K.; Webber, D.; Weidner, A.; Weinert, M.; Weinstein, A.; Weiss, R.; Wen, S.; Wette, K.; Whelan, J. T.; Whitbeck, D. M.; Whitcomb, S. E.; Whiting, B. F.; Wiley, S.; Wilkinson, C.; Willems, P. A.; Williams, L.; Willke, B.; Wilmut, I.; Winkler, W.; Wipf, C. C.; Wise, S.; Wiseman, A. G.; Woan, G.; Woods, D.; Wooley, R.; Worden, J.; Wu, W.; Yakushin, I.; Yamamoto, H.; Yan, Z.; Yoshida, S.; Yunes, N.; Zanolin, M.; Zhang, J.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M.; Zur Mühlen, H.; Zweizig, J.; Kramer, M.; Lyne, A. G.

    2007-08-01

    We present upper limits on the gravitational wave emission from 78 radio pulsars based on data from the third and fourth science runs of the LIGO and GEO 600 gravitational wave detectors. The data from both runs have been combined coherently to maximize sensitivity. For the first time, pulsars within binary (or multiple) systems have been included in the search by taking into account the signal modulation due to their orbits. Our upper limits are therefore the first measured for 56 of these pulsars. For the remaining 22, our results improve on previous upper limits by up to a factor of 10. For example, our tightest upper limit on the gravitational strain is 2.6×10-25 for PSR J1603-7202, and the equatorial ellipticity of PSR J2124 3358 is less than 10-6. Furthermore, our strain upper limit for the Crab pulsar is only 2.2 times greater than the fiducial spin-down limit.

  16. DISCOVERY OF GAMMA-RAY PULSATIONS FROM THE TRANSITIONAL REDBACK PSR J1227-4853

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, T. J. [College of Science, George Mason University, Fairfax, VA 22030 (United States); Ray, P. S.; Cheung, C. C. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Roy, J.; Bhattacharyya, B.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Pletsch, H. J.; Fort, S. [Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, D-30167 Hannover (Germany); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Deneva, J. [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); Kerr, M., E-mail: tyrel.j.johnson@gmail.com, E-mail: Paul.Ray@nrl.navy.mil, E-mail: jayanta.roy@manchester.ac.uk [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping NSW 1710 (Australia)

    2015-06-10

    The 1.69 ms spin period of PSR J1227−4853 was recently discovered in radio observations of the low-mass X-ray binary XSS J12270−4859 following the announcement of a possible transition to a rotation-powered millisecond pulsar state, inferred from decreases in optical, X-ray, and gamma-ray flux from the source. We report the detection of significant (5σ) gamma-ray pulsations after the transition, at the known spin period, using ∼1 year of data from the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The gamma-ray light curve of PSR J1227−4853 can be fit by one broad peak, which occurs at nearly the same phase as the main peak in the 1.4 GHz radio profile. The partial alignment of light-curve peaks in different wavebands suggests that at least some of the radio emission may originate at high altitude in the pulsar magnetosphere, in extended regions co-located with the gamma-ray emission site. We folded the LAT data at the orbital period, both pre- and post-transition, but find no evidence for significant modulation of the gamma-ray flux. Analysis of the gamma-ray flux over the mission suggests an approximate transition time of 2012 November 30. Continued study of the pulsed emission and monitoring of PSR J1227−4853, and other known redback systems, for subsequent flux changes will increase our knowledge of the pulsar emission mechanism and transitioning systems.

  17. High signal-to-noise ratio observations and the ultimate limits of precision pulsar timing

    CERN Document Server

    Oslowski, Stefan; Hobbs, George; Bailes, Matthew; Demorest, Paul

    2011-01-01

    We demonstrate that the sensitivity of high-precision pulsar timing experiments will be ultimately limited by the broadband intensity modulation that is intrinsic to the pulsar's stochastic radio signal. That is, as the peak flux of the pulsar approaches that of the system equivalent flux density, neither greater antenna gain nor increased instrumental bandwidth will improve timing precision. These conclusions proceed from an analysis of the covariance matrix used to characterise residual pulse profile fluctuations following the template matching procedure for arrival time estimation. We perform such an analysis on 25 hours of high-precision timing observations of the closest and brightest millisecond pulsar, PSR J0437-4715. In these data, the standard deviation of the post-fit arrival time residuals is approximately four times greater than that predicted by considering the system equivalent flux density, mean pulsar flux and the effective width of the pulsed emission. We develop a technique based on principa...

  18. The NANOGrav Nine-year Data Set: Mass and Geometric Measurements of Binary Millisecond Pulsars

    Science.gov (United States)

    Fonseca, Emmanuel; Pennucci, Timothy T.; Ellis, Justin A.; Stairs, Ingrid H.; Nice, David J.; Ransom, Scott M.; Demorest, Paul B.; Arzoumanian, Zaven; Crowter, Kathryn; Dolch, Timothy; Ferdman, Robert D.; Gonzalez, Marjorie E.; Jones, Glenn; Jones, Megan L.; Lam, Michael T.; Levin, Lina; McLaughlin, Maura A.; Stovall, Kevin; Swiggum, Joseph K.; Zhu, Weiwei

    2016-12-01

    We analyze 24 binary radio pulsars in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) nine-year data set. We make 14 significant measurements of the Shapiro delay, including new detections in four pulsar-binary systems (PSRs J0613-0200, J2017+0603, J2302+4442, and J2317+1439), and derive estimates of the binary-component masses and orbital inclination for these MSP-binary systems. We find a wide range of binary pulsar masses, with values as low as {m}{{p}}={1.18}-0.09+0.10 {M}⊙ for PSR J1918-0642 and as high as {m}{{p}}={1.928}-0.017+0.017 {M}⊙ for PSR J1614-2230 (both 68.3% credibility). We make an improved measurement of the Shapiro timing delay in the PSR J1918-0642 and J2043+1711 systems, measuring the pulsar mass in the latter system to be {m}{{p}}={1.41}-0.18+0.21 {M}⊙ (68.3% credibility) for the first time. We measure secular variations of one or more orbital elements in many systems, and use these measurements to further constrain our estimates of the pulsar and companion masses whenever possible. In particular, we used the observed Shapiro delay and periastron advance due to relativistic gravity in the PSR J1903+0327 system to derive a pulsar mass of {m}{{p}}={1.65}-0.02+0.02 {M}⊙ (68.3% credibility). We discuss the implications that our mass measurements have on the overall neutron-star mass distribution, and on the “mass/orbital-period” correlation due to extended mass transfer.

  19. The Green Bank Telescope 350 MHz Drift-scan Survey II: Data Analysis and the Timing of 10 New Pulsars, Including a Relativistic Binary

    CERN Document Server

    Lynch, Ryan S; Ransom, Scott M; Stairs, Ingrid H; Lorimer, Duncan R; McLaughlin, Maura A; Hessels, Jason W T; Kaspi, Victoria M; Kondratiev, Vladislav I; Archibald, Anne M; Berndsen, Aaron; Cardoso, Rogerio F; Cherry, Angus; Karako-Argaman, Chen; van Leeuwen, Joeri; McPhee, Christie A; Pennucci, Tim; Roberts, Mallory S E

    2012-01-01

    We have completed a 350 MHz drift scan survey using the Robert C. Byrd Green Bank Telescope with the goal of finding new radio pulsars, especially millisecond pulsars that can be timed to high precision. This survey covered ~10300 square degrees and all of the data have now been fully processed. We have discovered a total of 31 new pulsars, seven of which are recycled pulsars. A companion paper by Boyles et al. (2012) describes the survey strategy, sky coverage, and instrumental set-up, and presents timing solutions for the first 13 pulsars. Here we describe the data analysis pipeline, survey sensitivity, and follow-up observations of new pulsars, and present timing solutions for 10 other pulsars. We highlight several sources---two interesting nulling pulsars, an isolated millisecond pulsar with a measurement of proper motion, and a partially recycled pulsar, PSR J0348+0432, which has a white dwarf companion in a relativistic orbit. PSR J0348+0432 will enable unprecedented tests of theories of gravity.

  20. Quasi-periodical variations of pulsars spin as mimicry of differential rotation

    Science.gov (United States)

    Kitiashvili, I.; Gusev, A.

    2008-09-01

    ABSTRACT Observation of pulsars is a powerful source of information for studying the dynamics and internal structure of neutron stars. Known about quasi-periodical fluctuations of the time-of-arrival of radiation(TOA) for some pulsars, which we explain as Chandler wobble, Free core nutation, Free inner core nutation and Inner core wobble in case three layer model. Using hamilton approximation to theory rotation of multilayer celestial bodies we estimate dynamical flattening for different layers for PSR B1828-11. It is known that an innate feature of pulsar radiation is high stability of the time-of-arrival (TOA) of pulses, and therefore the analysis of TOA fluctuations can reflect subtle effects of neutron stars dynamics. TOA variations of pulsars can be interpreted by three reasons: gravitational perturbation of pulsar by planetary bodies, peculiarities of a pulsar interior like Tkachenko oscillations and free precession motion, when axis of rotation do not coincide with vectors of the angular moment of solid crust, liquid outer core and crystal core. The radial velocity of a star is obtained by measuring the magnitude of the Doppler effect in its spectrum. Stars showing a small amplitude variation of the radial velocity can be interpreted as systems having planetary companions. Assuming that the pulsar PSR B1257+12 has a mass of 1:35M¯, the Keplerian orbital radii are 0.9, 1.4 and 2.1 AU and with masses are 3:1M©=sin(i), 10:2M©=sin(i), 4:6M©=sin(i), where i is the orbital inclination [7]. In 2000, Stairs, Lyne and Shemar reported about their discovery of long-term, highly-periodic and correlated variations of pulse shape and the rate of slow-down of the pulsar PSR B182811 with period variations approximately 1000, 500, 250 and 167 days, which may be a result of the spin axis caused by an asymmetry in the shape of the pulsar. The long-periodic precession phenomenon was also detected for a few pulsars: PSR 2217+47, PSR 0531+21, PSR B083345, PSR B182811, PSR B

  1. Binary pulsar with a very small mass function

    Science.gov (United States)

    Dewey, R. J.; Maguire, C. M.; Rawley, L. A.; Stokes, G. H.; Taylor, J. H.

    1986-08-01

    Radiotelescope pulse-arrival-time (PAT) data of PSR1831-00, primarily at 390 MHz, were collected to characterize the evolution of the binary pulsars. The data were used to calculate, the right ascension and declination, pulsar and orbital periods, dispersion measure, semi-major axis, eccentricity, and time of periastron. The orbital period and semi-major axis are used to calculate the mass function. Comparisons are made with other binary and millisecond pulsars, noting the high degree of similarity with the other objects. The limitations imposed on the evolution of the objects by the observed physical characteristics lead to two possible evolutionary models: mass transfer after or during the formation of the neutron star, or no mass transfer. The first model would have required a contact phase during evolution of the primary. The second model posits a three solar mass primary which was also in contact during its evolution and which went to supernova.

  2. An active, asynchronous companion to a redback millisecond pulsar

    CERN Document Server

    van Staden, André

    2016-01-01

    PSR\\,J1723$-$2837 is a "redback" millisecond pulsar (MSP) with a low-mass companion in a 14.8\\,h orbit. The system's properties closely resemble those of "transitional" MSPs that alternate between spin-down and accretion-powered states. In this paper we report on long-term photometry of the 15.5\\,mag companion to the pulsar. We use our data to illustrate that the star experiences sporadic activity which we attribute to starspots. We also find that the companion is not tidally locked and infer $P_{\\rm s}/P_{\\rm b}= 0.9974(7)$ for the ratio between the rotational and orbital periods. We place constraints on various parameters, including the irradiation efficiency and pulsar mass. Finally, we discuss similarities with other redback MSPs and conclude that starspots provide the most likely explanation for the often seen irregular and asymmetric optical lightcurves.

  3. An Active, Asynchronous Companion to a Redback Millisecond Pulsar

    Science.gov (United States)

    van Staden, André D.; Antoniadis, John

    2016-12-01

    PSR J1723-2837 is a “redback” millisecond pulsar (MSP) with a low-mass companion in a 14.8 hr orbit. The system’s properties closely resemble those of “transitional” MSPs that alternate between spin-down and accretion-powered states. In this Letter, we report on long-term photometry of the 15.5 mag companion to the pulsar. We use our data to illustrate that the star experiences sporadic activity, which we attribute to starspots. We also find that the companion is not tidally locked and infer {P}{{s}}/{P}{{b}}=0.9974(7) for the ratio between the rotational and orbital periods. Finally, we place constraints on various parameters, including the irradiation efficiency and pulsar mass. We discuss similarities with other redback MSPs and conclude that starspots may provide the most likely explanation for the often seen irregular and asymmetric optical light curves.

  4. A glitch in the millisecond pulsar J0613-0200

    CERN Document Server

    McKee, J W; Stappers, B W; Lyne, A G; Caballero, R N; Lentati, L; Desvignes, G; Jessner, A; Jordan, C A; Karuppusamy, R; Kramer, M; Cognard, I; Champion, D J; Graikou, E; Lazarus, P; Osłowski, S; Perrodin, D; Shaifullah, G; Tiburzi, C; Verbiest, J P W

    2016-01-01

    We present evidence for a small glitch in the spin evolution of the millisecond pulsar J0613$-$0200, using the EPTA Data Release 1.0, combined with Jodrell Bank analogue filterbank TOAs recorded with the Lovell telescope and Effelsberg Pulsar Observing System TOAs. A spin frequency step of 0.82(3) nHz and frequency derivative step of ${-1.6(39) \\times 10^{-19}\\,\\text{Hz} \\ \\text{s}^{-1}}$ are measured at the epoch of MJD 50888(30). After PSR B1821$-$24A, this is only the second glitch ever observed in a millisecond pulsar, with a fractional size in frequency of ${\\Delta \

  5. X-ray observations of black widow pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Gentile, P. A.; McLaughlin, M. A. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Roberts, M. S. E. [Eureka Scientific Inc., 2452 Delmer Street, Suite 100, Oakland, CA 94602-3017 (United States); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Hessels, J. W. T. [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Kerr, M. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States); Ransom, S. M. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Ray, P. S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)

    2014-03-10

    We describe the first X-ray observations of five short orbital period (P{sub B} < 1 day), γ-ray emitting, binary millisecond pulsars (MSPs). Four of these—PSRs J0023+0923, J1124–3653, J1810+1744, and J2256–1024—are 'black-widow' pulsars, with degenerate companions of mass <<0.1 M {sub ☉}, three of which exhibit radio eclipses. The fifth source, PSR J2215+5135, is an eclipsing 'redback' with a near Roche-lobe filling ∼0.2 solar mass non-degenerate companion. Data were taken using the Chandra X-Ray Observatory and covered a full binary orbit for each pulsar. Two pulsars, PSRs J2215+5135 and J2256–1024, show significant orbital variability while PSR J1124–3653 shows marginal orbital variability. The lightcurves for these three pulsars have X-ray flux minima coinciding with the phases of the radio eclipses. This phenomenon is consistent with an intrabinary shock emission interpretation for the X-rays. The other two pulsars, PSRs J0023+0923 and J1810+1744, are fainter and do not demonstrate variability at a level we can detect in these data. All five spectra are fit with three separate models: a power-law model, a blackbody model, and a combined model with both power-law and blackbody components. The preferred spectral fits yield power-law indices that range from 1.3 to 3.2 and blackbody temperatures in the hundreds of eV. The spectrum for PSR J2215+5135 shows a significant hard X-ray component, with a large number of counts above 2 keV, which is additional evidence for the presence of intrabinary shock emission. This is similar to what has been detected in the low-mass X-ray binary to MSP transition object PSR J1023+0038.

  6. Pulsars at Parkes

    CERN Document Server

    Manchester, R N

    2012-01-01

    The first pulsar observations were made at Parkes on March 8, 1968, just 13 days after the publication of the discovery paper by Hewish and Bell. Since then, Parkes has become the world's most successful pulsar search machine, discovering nearly two thirds of the known pulsars, among them many highly significant objects. It has also led the world in pulsar polarisation and timing studies. In this talk I will review the highlights of pulsar work at Parkes from those 1968 observations to about 2006 when the Parkes Multibeam Pulsar Survey was essentially completed and the Parkes Pulsar Timing Array project was established.

  7. Discovery of gamma and X-ray pulsations from the young and energetic PSR J1357-6429 with Fermi and XMM-Newton

    CERN Document Server

    Lemoine-Goumard, M; Grondin, M -H; Shannon, R; Smith, D A; Burgay, M; Camilo, F; Cohen-Tanugi, J; Freire, P C C; Grove, J E; Guillemot, L; Johnston, S; Keith, M; Kramer, M; Manchester, R N; Michelson, P F; Parent, D; Possenti, A; Ray, P S; Renaud, M; Thorsett, S E; Weltevrede, P; Wolff, M T

    2011-01-01

    Since the launch of the Fermi satellite, the number of known gamma-ray pulsars has increased tenfold. Most gamma-ray detected pulsars are young and energetic, and many are associated with TeV sources. PSR J1357-6429 is a high spin-down power pulsar (Edot = 3.1 * 10^36 erg/s), discovered during the Parkes multibeam survey of the Galactic plane, with significant timing noise typical of very young pulsars. In the very-high-energy domain, H.E.S.S. has reported the detection of the extended source HESS J1356-645 (intrinsic Gaussian width of 12') whose centroid lies 7' from PSR J1357-6429. Using a rotational ephemeris obtained with 74 observations made with the Parkes telescope at 1.4 GHz, we phase-fold more than two years of gamma-ray data acquired by Fermi-LAT as well as those collected with XMM-Newton, and perform gamma-ray spectral modeling. Significant gamma and X-ray pulsations are detected from PSR J1357-6429. The light curve in both bands shows one broad peak. Gamma-ray spectral analysis of the pulsed emiss...

  8. The discovery of two mildly recycled binary pulsars in the Northern High Time Resolution Universe pulsar survey

    Science.gov (United States)

    Berezina, M.; Champion, D. J.; Freire, P. C. C.; Tauris, T. M.; Kramer, M.; Lyne, A. G.; Stappers, B. W.; Guillemot, L.; Cognard, I.; Barr, E. D.; Eatough, R. P.; Karuppusamy, R.; Spitler, L. G.; Desvignes, G.

    2017-10-01

    We report the discovery and the results of follow-up timing observations of PSR J2045+3633 and PSR J2053+4650, two binary pulsars found in the Northern High Time Resolution Universe pulsar survey being carried out with the Effelsberg radio telescope. Having spin periods of 31.7 and 12.6 ms, respectively, and both with massive white dwarf companions, Mc > 0.8 M⊙, the pulsars can be classified as mildly recycled. PSR J2045+3633 is remarkable due to its orbital period (32.3 d) and eccentricity e = 0.017 212 44(5), which is amongst the largest ever measured for this class. After almost two years of timing, the large eccentricity has allowed the measurement of the rate of advance of periastron at the 5σ level, 0.0010(2)°yr- 1. Combining this with a detection of the orthometric amplitude of the Shapiro delay, we obtained the following constraints on the component masses (within general relativity): Mp = 1.33^{+0.30}_{-0.28} M_{⊙}; and Mc = 0.94^{+0.14}_{-0.13} M_{⊙}. PSR J2053+4650 has a 2.45 d circular orbit inclined to the plane of the sky at an angle i = 85.0^{+0.8}_{-0.9} deg. In this nearly edge-on case the masses can be obtained from the Shapiro delay alone. Our timing observations resulted in a significant detection of this effect giving: Mp = 1.40^{+0.21}_{-0.18} M_{⊙}; and Mc = 0.86^{+0.07}_{-0.06} M_{⊙}.

  9. Simultaneous multi-frequency single pulse observations of pulsars

    Science.gov (United States)

    Naidu, A.; Joshi, B. C.; Manoharan, P. K.; KrishnaKumar, M. A.

    2017-08-01

    Aims: We report on simultaneous multi-frequency single pulse observations of a sample of pulsars with previously reported, frequency dependent subpulse drift inferred from non-simultaneous and short observations. We aim to clarify if the frequency dependence is a result of multiple drift modes in these pulsars. Methods: We performed simultaneous observations at 326.5 MHz with the Ooty Radio Telescope and at 326, 610, and 1308 MHz with the Giant Meterwave Radio Telescope for a sample of 12 pulsars, where frequency dependent single pulse behaviour was reported. The single pulse sequences were analysed with three types of fluctuation analysis techniques, namely longitude-resolved fluctuation spectrum technique, two-dimensional fluctuation spectrum technique and sliding two-dimensional fluctuation spectrum technique. The first two techniques are sensitive to average fluctuation properties of the pulses, whereas the last technique is used for examining the temporal behaviour of the pulses. Results: We report subpulse drifting in PSR J0934-5249 for the first time. We also report pulse nulling measurements in PSRs J0934-5249, B1508+55, J1822-2256, B1845-19, and J1901-0906 for the first time. Our measurements of subpulse drifting and pulse nulling for the rest of the pulsars are consistent with previously reported values. Contrary to previous belief, we find no evidence for a frequency dependent drift pattern in PSR B2016+28 as reported in previous studies. In PSRs B1237+25, J1822-2256, J1901-0906, and B2045-16, our longer and more sensitive observations reveal multiple drift rates with distinct P3. We increase the sample of pulsars showing concurrent nulling across multiple frequencies by more than 100 percent, adding four more pulsars to this sample. Our results confirm and further strengthen the understanding that the subpulse drifting and pulse nulling are consistent in the broadband with previous studies and are closely tied to physics of polar gap.

  10. X-ray states of redback millisecond pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Linares, M. [Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain)

    2014-11-01

    Compact binary millisecond pulsars with main-sequence donors, often referred to as 'redbacks', constitute the long-sought link between low-mass X-ray binaries and millisecond radio pulsars and offer a unique probe of the interaction between pulsar winds and accretion flows. We present a systematic study of eight nearby redbacks, using more than 100 observations obtained with Swift's X-ray Telescope. We distinguish between three main states: pulsar, disk, and outburst states. We find X-ray mode switching in the disk state of PSR J1023+0038 and XSS J12270-4859, similar to what was found in the other redback that showed evidence for accretion: rapid, recurrent changes in X-ray luminosity (0.5-10 keV, L {sub X}), between (6-9) × 10{sup 32} erg s{sup –1} (disk-passive state) and (3-5) × 10{sup 33} erg s{sup –1} (disk-active state). This strongly suggests that mode switching—which has not been observed in quiescent low-mass X-ray binaries—is universal among redback millisecond pulsars in the disk state. We briefly explore the implications for accretion disk truncation and find that the inferred magnetospheric radius in the disk state of PSR J1023+0038 and XSS J12270-4859 lies outside the light cylinder. Finally, we note that all three redbacks that have developed accretion disks have relatively high L {sub X} in the pulsar state (>10{sup 32} erg s{sup –1}).

  11. 脉冲星巡天观测进展和近邻脉冲星样本估算%Progress on Radio Pulsar Survey and Estimate the Neighbor Pulsar Population

    Institute of Scientific and Technical Information of China (English)

    张蕾; 王培; 李菂; 张洁; 岳友岭; 刘姝

    2015-01-01

    射电脉冲星巡天是探测获取更多脉冲星的重要途径.首先介绍了影响射电脉冲星巡天效率的因素,着重分析灵敏度和观测频率两个重要因素,并通过定义脉冲星探测率,简化对脉冲星巡天效率的估算.此外,总结了现有脉冲星巡天项目,利用Parkes多波束脉冲星及两次扩充巡天(Swinburne中纬度脉冲星巡天和Parkes高纬度脉冲星巡天)结果,采用包含时间演化的脉冲星分布模拟软件PsrPopPy,模拟得到脉冲星在银河系中分布的样本,并对近邻太阳系1kpc距离内的脉冲星数目进行了估算,获得了近邻脉冲星样本,可为脉冲星高能辐射对探测宇宙线正电子谱影响等研究提供可靠输入量.%Radio surveys are an important way to detect new pulsars. We first reviewed the main factors affecting sensitivities of pulsar searches in radio bands. These factors can be grouped into two categories. First, the instrumental factors include telescope size, observation frequency, observation bandwidth, integration time, sampling rate, digitization loss, and system temperature. Second, the intrinsic properties of pulsars include dispersion, period, and effective pulse width. We defined a generic detection rate (DR) that combine all these factors to be the number of pulsars detected with specific integration time per pointing. We summarized the results of all radio pulsar surveys. The most successful pulsar survey so far is Parkes multibeam pulsar survey (PKSMB), which detected 1086 normal pulsars. The PKSMB was expanded by two more surveys, namely, Parkes-Swinbume multibeam survey (PKSSW) and Parkes high-latitude multibeam pulsar survey (PKSHL), which in total detected 1377 normal pulsars. We utilized the software package PsrPopPy, which adopts a time evolution model of pulsar parameters, to simulate the Galactic pulsar distribution. The results of Parkes multi-beam pulsar survey and its two extensions were used as inputs of PsrPopPy to constrain

  12. OBSERVATIONS OF ENERGETIC HIGH MAGNETIC FIELD PULSARS WITH THE FERMI LARGE AREA TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Parent, D.; Abdo, A. A. [College of Science, George Mason University, Fairfax, VA 22030 (United States); Kerr, M.; Den Hartog, P. R.; Romani, R. W.; Watters, K.; Craig, H. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baring, M. G. [Rice University, Department of Physics and Astronomy, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); DeCesar, M. E.; Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Espinoza, C. M.; Stappers, B. W.; Weltevrede, P. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, M13 9PL (United Kingdom); Gotthelf, E. V.; Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Johnston, S. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping NSW 1710 (Australia); Kaspi, V. M.; Livingstone, M. [Department of Physics, McGill University, Montreal, PQ, H3A 2T8 (Canada); Burgay, M. [INAF-Cagliari Astronomical Observatory, I-09012 Capoterra (Italy); Freire, P. C. C., E-mail: dmnparent@gmail.com, E-mail: kerrm@stanford.edu, E-mail: hartog@stanford.edu [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); and others

    2011-12-20

    We report the detection of {gamma}-ray pulsations from the high-magnetic-field rotation-powered pulsar PSR J1119-6127 using data from the Fermi Large Area Telescope. The {gamma}-ray light curve of PSR J1119-6127 shows a single, wide peak offset from the radio peak by 0.43 {+-} 0.02 in phase. Spectral analysis suggests a power law of index 1.0 {+-} 0.3{sup +0.4}{sub -0.2} with an energy cutoff at 0.8 {+-} 0.2{sup +2.0}{sub -0.5} GeV. The first uncertainty is statistical and the second is systematic. We discuss the emission models of PSR J1119-6127 and demonstrate that despite the object's high surface magnetic field-near that of magnetars-the field strength and structure in the {gamma}-ray emitting zone are apparently similar to those of typical young pulsars. Additionally, we present upper limits on the {gamma}-ray pulsed emission for the magnetically active PSR J1846-0258 in the supernova remnant Kesteven 75 and two other energetic high-B pulsars, PSRs J1718-3718 and J1734-3333. We explore possible explanations for the non-detection of these three objects, including peculiarities in their emission geometry.

  13. Observations of Energetic High Magnetic Field Pulsars with the Fermi Large Area Telescope

    CERN Document Server

    Parent, D; Hartog, P R Den; Baring, M G; DeCesar, M E; Espinoza, C M; Gotthelf, E V; Harding, A K; Johnston, S; Kaspi, V M; Livingstone, M; Romani, R W; Stappers, B W; Watters, K; Weltevrede, P; Abdo, A A; Burgay, M; Camilo, F; Craig, H A; Freire, P C C; Giordano, F; Guillemot, L; Hobbs, G; Keith, M; Kramer, M; Lyne, A G; Manchester, R N; Noutsos, A; Possenti, A; Smith, D A

    2011-01-01

    We report the detection of gamma-ray pulsations from the high-magnetic-field rotation-powered pulsar PSR J1119-6127 using data from the Fermi Large Area Telescope. The gamma-ray light curve of PSR J1119-6127 shows a single, wide peak offset from the radio peak by 0.43 pm 0.02 in phase. Spectral analysis suggests a power law of index 1.0 pm 0.3 with an energy cut-off at 0.8 pm 0.2 GeV. The first uncertainty is statistical and the second is systematic. We discuss the emission models of PSR J1119-6127 and demonstrate that despite the object's high surface magnetic field---near that of magnetars---the field strength and structure in the gamma-ray emitting zone are apparently similar to those of typical young pulsars. Additionally, we present upper limits on the \\gam-ray pulsed emission for the magnetically active PSR J1846-0258 in the supernova remnant Kesteven 75 and two other energetic high-B pulsars, PSRs J1718-3718 and J1734-3333. We explore possible explanations for the non-detection of these three objects, ...

  14. The High Time Resolution Universe Pulsar Survey XII : Galactic plane acceleration search and the discovery of 60 pulsars

    CERN Document Server

    Ng, C; Bailes, M; Barr, E D; Bates, S D; Bhat, N D R; Burgay, M; Burke-Spolaor, S; Flynn, C M L; Jameson, A; Johnston, S; Keith, M J; Kramer, M; Levin, L; Petroff, E; Possenti, A; Stappers, B W; van Straten, W; Tiburzi, C; Eatough, R P; Lyne, A G

    2015-01-01

    We present initial results from the low-latitude Galactic plane region of the High Time Resolution Universe pulsar survey conducted at the Parkes 64-m radio telescope. We discuss the computational challenges arising from the processing of the terabyte-sized survey data. Two new radio interference mitigation techniques are introduced, as well as a partially-coherent segmented acceleration search algorithm which aims to increase our chances of discovering highly-relativistic short-orbit binary systems, covering a parameter space including potential pulsar-black hole binaries. We show that under a constant acceleration approximation, a ratio of data length over orbital period of ~0.1 results in the highest effectiveness for this search algorithm. From the 50 per cent of data processed thus far, we have re-detected 435 previously known pulsars and discovered a further 60 pulsars, two of which are fast-spinning pulsars with periods less than 30ms. PSR J1101-6424 is a millisecond pulsar whose heavy white dwarf (WD)...

  15. The Pulsar Search Collaboratory: Discovery and Timing of Five New Pulsars

    CERN Document Server

    Rosen, R; McLaughlin, M A; Lorimer, D R; Yun, M; Heatherly, S; Boyles, J; Lynch, R; Kondratiev, V I; Scoles, S; Ransom, S M; Moniot, M L; Cottrill, A; Weaver, M; Snider, A; Thompson, C; Raycraft, M; Dudenhoefer, J; Allphin, L; Thorley, J; Meadows, B; Marchiny, G; Liska, A; O'Dwyer, A M; Butler, B; Bloxton, S; Mabry, H; Abate, H; Boothe, J; Pritt, S; Alberth, J; Green, A; Crowley, R J; Agee, A; Nagley, S; Sargent, N; Hinson, E; Smith, K; McNeely, R; Quigley, H; Pennington, A; Chen, S; Maynard, T; Loope, L; Bielski, N; McGough, J R; Gural, J C; Colvin, S; Tso, S; Ewen, Z; Zhang, M; Ciccarella, N; Bukowski, B; Novotny, C B; Gore, J; Sarver, K; Johnson, S; Cunningham, H; Collins, D; Gardner, D; Monteleone, A; Hall, J; Schweinhagen, R; Ayers, J; Jay, S; Uosseph, B; Dunkum, D; Pal, J; Dydiw, S; Sterling, M; Phan, E

    2012-01-01

    We present the discovery and timing solutions of five new pulsars by students involved in the Pulsar Search Collaboratory (PSC), a NSF-funded joint program between the National Radio Astronomy Observatory and West Virginia University designed to excite and engage high-school students in Science, Technology, Engineering, and Mathematics (STEM) and related fields. We encourage students to pursue STEM fields by apprenticing them within a professional scientific community doing cutting edge research, specifically by teaching them to search for pulsars. The students are analyzing 300 hours of drift-scan survey data taken with the Green Bank Telescope at 350 MHz. These data cover 2876 square degrees of the sky. Over the course of five years, more than 700 students have inspected diagnostic plots through a web-based graphical interface designed for this project. The five pulsars discovered in the data have spin periods ranging from 3.1 ms to 4.8 s. Among the new discoveries are - PSR J1926-1314, a long period, nulli...

  16. OSCILLATION-DRIVEN MAGNETOSPHERIC ACTIVITY IN PULSARS

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Meng-Xiang; Xu, Ren-Xin; Zhang, Bing, E-mail: linmx97@gmail.com, E-mail: r.x.xu@pku.edu.cn, E-mail: zhang@physics.unlv.edu [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China)

    2015-02-01

    We study the magnetospheric activity in the polar cap region of pulsars under stellar oscillations. The toroidal oscillation of the star propagates into the magnetosphere, which provides additional voltage due to unipolar induction, changes Goldreich-Julian charge density from the traditional value due to rotation, and hence influences particle acceleration. We present a general solution of the effect of oscillations within the framework of the inner vacuum gap model and consider three different inner gap modes controlled by curvature radiation, inverse Compton scattering, and two-photon annihilation, respectively. With different pulsar parameters and oscillation amplitudes, one of three modes would play a dominant role in defining the gap properties. When the amplitude of oscillation exceeds a critical value, mode changing occurs. Oscillations also lead to a change of the size of the polar cap. As applications, we show the inner gap properties under oscillations in both normal pulsars and anomalous X-ray pulsars/soft gamma-ray repeaters (AXPs/SGRs). We interpret the onset of radio emission after glitches/flares in AXPs/SGRs as due to oscillation-driven magnetic activities in these objects, within the framework of both the magnetar model and the solid quark star model. Within the magnetar model, radio activation may be caused by the enlargement of the effective polar cap angle and the radio emission beam due to oscillation, whereas within the solid quark star angle, it may be caused by activation of the pulsar inner gap from below the radio emission death line due to an oscillation-induced voltage enhancement. The model can also explain the glitch-induced radio profile change observed in PSR J1119–6127.

  17. The Arecibo 430-MHz Intermediate Galactic Latitude Survey: Discovery of Nine Radio Pulsars

    CERN Document Server

    Navarro, J; Freire, P C; Navarro, Jose; Anderson, Stuart; Freire, Paulo C.

    2003-01-01

    We have used the Arecibo Radio Telescope to search for millisecond pulsars in two intermediate Galactic latitude regions (7 deg < | b | < 20 deg) accessible to this telescope. For these latitudes the useful millisecond pulsar search volume achieved by Arecibo's 430-MHz beam is predicted to be maximal. Searching a total of 130 square degrees, we have discovered nine new pulsars and detected four previously known objects. We compare the results of this survey with those of other 430-MHz surveys carried out at Arecibo and of an intermediate latitude survey made at Parkes that included part of our search area; the latter independently found two of the nine pulsars we have discovered. At least six of our discoveries are isolated pulsars with ages between 5 and 300 Myr; one of these, PSR J1819+1305, exhibits very marked and periodic nulling. We have also found a recycled pulsar, PSR J2016+1948. With a rotational period of 65 ms, this is a member of a binary system with a 635-day orbital period. We discuss som...

  18. New long-term braking index measurements for glitching pulsars using a glitch-template method

    CERN Document Server

    Espinoza, C M; Stappers, B W

    2016-01-01

    Braking index measurements offer the opportunity to explore the processes affecting the long-term spin evolution of pulsars and possible evolutionary connections between the various pulsar populations. For young pulsars the long-term trends are generally obscured by short term phenomena such as timing noise and the recoveries form large glitches. Here we present a new method to overcome the latter and report on braking index measurements for the Vela-like pulsars PSR B1800-21 and PSR B1823-13, an updated measurement for Vela and new estimates for four more glitching pulsars observed at Jodrell Bank Observatory. The values of braking indices describe the long-term evolution of the pulsars across the P-P' diagram. Despite some measurements being affected by considerable uncertainties, there is evidence for a common trend involving low braking indices (n 10. We interpret both short and long term trends as signatures of the large glitch activity, and speculate that they are driven by short-term post-glitch re-cou...

  19. New long-term braking index measurements for glitching pulsars using a glitch-template method

    Science.gov (United States)

    Espinoza, C. M.; Lyne, A. G.; Stappers, B. W.

    2017-04-01

    Braking index measurements offer the opportunity to explore the processes affecting the long-term spin evolution of pulsars and possible evolutionary connections between the various pulsar populations. In most cases, such measurements are difficult because of the presence of short-term phenomena, such as glitches and timing noise, which obscure the long-term trends. In particular, recoveries from large glitches are the main obstacle to measuring the braking indices of young pulsars like the Vela and Crab pulsars. We present a new method to overcome this problem and report on braking index measurements for the Vela-like pulsars, PSR B1800-21 and PSR B1823-13, together with an updated measurement for Vela. Additionally, the use of the method is extended to six more young glitching pulsars observed at Jodrell Bank Observatory and we are able to estimate four new braking indices. Values of braking indices describe the long-term evolution of the pulsars across the P-dot{P} diagram. Despite some measurements being affected by considerable uncertainties, there is evidence for a common trend among young glitching pulsars, characterized by low braking indices n ≤ 2. Such values introduce a new variant in the evolution of young pulsars, and their relationship with other populations in the P-dot{P} diagram, and imply that these pulsars could be a few times older than indicated by standard formulae. In this context, we analyse the case of PSR B1757-24 and conclude that the pulsar could be old enough to be related to the supernova remnant G5.4-1.2. Between glitches, the short-term evolution of Vela-like pulsars is characterized by large interglitch braking indices nig > 10. We interpret both short- and long-term trends as signatures of the large glitch activity, and speculate that they are driven by short-term post-glitch re-coupling and a cumulative long-term decoupling of superfluid to the rotation of the star.

  20. A detailed X-ray investigation of PSR J2021+4026 and $\\gamma$-Cygni supernova remnant

    CERN Document Server

    Hui, C Y; Lin, L C C; Huang, R H H; Hu, C P; Wu, J H K; Trepl, L; Takata, J; Wang, Y; Chou, Y; Cheng, K S; Kong, A K H

    2014-01-01

    We have investigated the field around the radio-quiet $\\gamma$-ray pulsar, PSR J2021+4026, with a ~140 ks XMM-Newton observation and a ~56 ks archival Chandra data. Through analyzing the pulsed spectrum, we show that the X-ray pulsation is purely thermal in nature which suggests the pulsation is originated from a hot polar cap with $T\\sim3\\times10^{6}$ K on the surface of a rotating neutron star. On the other hand, the power-law component that dominates the pulsar emission in the hard band is originated from off-pulse phases, which possibly comes from a pulsar wind nebula. In re-analyzing the Chandra data, we have confirmed the presence of bow-shock nebula which extends from the pulsar to west by ~10 arcsec. The orientation of this nebular feature suggests that the pulsar is probably moving eastward which is consistent with the speculated proper motion by extrapolating from the nominal geometrical center of the supernova remnant (SNR) G78.2+2.1 to the current pulsar position. For G78.2+2.1, our deep XMM-Newto...

  1. The Parkes multibeam pulsar survey: VII. Timing of four millisecond pulsars and the underlying spin period distribution of the Galactic millisecond pulsar population

    CERN Document Server

    Lorimer, D R; Manchester, R N; Possenti, A; Lyne, A G; McLaughlin, M A; Kramer, M; Hobbs, G; Stairs, I H; Burgay, M; Eatough, R P; Keith, M J; Faulkner, A J; D'Amico, N; Camilo, F; Corongiu, A; Crawford, F

    2015-01-01

    We present timing observations of four millisecond pulsars discovered in the Parkes 20-cm multibeam pulsar survey of the Galactic plane. PSRs J1552-4937 and J1843-1448 are isolated objects with spin periods of 6.28 and 5.47 ms respectively. PSR J1727-2946 is in a 40-day binary orbit and has a spin period of 27 ms. The 4.43-ms pulsar J1813-2621 is in a circular 8.16-day binary orbit around a low-mass companion star with a minimum companion mass of 0.2 solar masses. Combining these results with detections from five other Parkes multibeam surveys, gives a well-defined sample of 56 pulsars with spin periods below 20 ms. We develop a likelihood analysis to constrain the functional form which best describes the underlying distribution of spin periods for millisecond pulsars. The best results were obtained with a log-normal distribution. A gamma distribution is less favoured, but still compatible with the observations. Uniform, power-law and Gaussian distributions are found to be inconsistent with the data. Galactic...

  2. Fermi-LAT constraints on the Pulsar Wind Nebula nature of HESS J1857+026

    CERN Document Server

    Rousseau, R; Van Etten, A; Lemoine-Goumard, M; Bogdanov, S; Hessels, J W T; Kaspi, V M; Arzoumanian, Z; Camilo, F; Casandjian, J M; Espinoza, C M; Johnston, S; Lyne, A G; Smith, D A; Stappers, B W; Caliandro, G A

    2012-01-01

    Since its launch, the Fermi satellite has firmly identified 5 pulsar wind nebulae plus a large number of candidates, all powered by young and energetic pulsars. HESS J1857+026 is a spatially extended gamma-ray source detected by H.E.S.S. and classified as a possible pulsar wind nebula candidate powered by PSR J1856+0245. We search for gamma-ray pulsations from PSR J1856+0245 and explore the characteristics of its associated pulsar wind nebula. Using a rotational ephemeris obtained from the Lovell telescope at Jodrell Bank Observatory at 1.5 GHz, we phase-fold 36 months of gamma-ray data acquired by the Large Area Telescope (LAT) aboard Fermi. We also perform a complete gamma-ray spectral and morphological analysis. No gamma-ray pulsations were detected from PSR J1856+0245. However, significant emission is detected at a position coincident with the TeV source HESS J1857+026. The gamma-ray spectrum is well described by a simple power-law with a spectral index of 1.53 \\pm 0.11_{\\rm stat} \\pm 0.55_{\\rm syst}$ and...

  3. The NANOGrav Nine-year Data Set: Mass and Geometric Measurements of Binary Millisecond Pulsars

    CERN Document Server

    Fonseca, Emmanuel; Ellis, Justin A; Stairs, Ingrid H; Nice, David J; Ransom, Scott M; Demorest, Paul B; Arzoumanian, Zaven; Crowter, Kathryn; Dolch, Timothy; Ferdman, Robert D; Gonzalez, Marjorie E; Jones, Glenn; Jones, Megan L; Lam, Michael T; Levin, Lina; McLaughlin, Maura A; Stovall, Kevin; Swiggum, Joseph K; Zhu, Weiwei

    2016-01-01

    We analyse 24 binary radio pulsars in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) nine-year data set. We made fourteen significant measurements of Shapiro delay, including new detections in four pulsar-binary systems (PSRs J0613$-$0200, J2017+0603, J2302+4442, and J2317+1439), and derive estimates of the binary-component masses and orbital inclination for these MSP-binary systems. We find a wide range of binary pulsar masses, with values as low as $m_{\\rm p} = 1.18^{+0.10}_{-0.09}\\text{ M}_{\\odot}$ for PSR J1918$-$0642 and as high as $m_{\\rm p} = 1.928^{+0.017}_{-0.017}\\text{ M}_{\\odot}$ for PSR J1614$-$2230 (both 68.3\\% confidence). We make an improved measurement of the Shapiro timing delay in the PSR J1918$-$0642 and J2043+1711 systems, measuring the pulsar mass in the latter system to be $m_{\\rm p} = 1.41^{+0.21}_{-0.18}\\text{ M}_{\\odot}$ (68.3\\% confidence) for the first time. We measure secular variations of one or more orbital elements in many systems, and use these meas...

  4. Shining Light on Quantum Gravity with Pulsar-Black Hole Binaries

    CERN Document Server

    Estes, John; Lippert, Matthew; Simonetti, John H

    2016-01-01

    Pulsars are some of the most accurate clocks found in nature, while black holes offer a unique arena for the study of quantum gravity. As such, pulsar-black hole (PSR-BH) binaries provide ideal astrophysical systems for detecting effects of quantum gravity. With the success of aLIGO and the advent of instruments like the SKA and eLISA, the prospects for discovery of such PSR-BH binaries are very promising. We argue that PSR-BH binaries can serve as ready-made testing grounds for proposed resolutions to the black hole information paradox. We propose using timing signals from a pulsar beam passing through the region near a BH event horizon as a probe of quantum gravitational effects. In particular, we demonstrate that fluctuations of the geometry outside a black hole lead to an increase in the measured root-mean-square deviation of arrival times of pulsar pulses traveling near the horizon. This allows for a clear observational test of the nonviolent nonlocality proposal for black hole information escape. For a ...

  5. The identification of the optical companion to the binary millisecond pulsar J0610-2100 in the Galactic field

    OpenAIRE

    C. Pallanca(University of Bologna); Mignani, R. P.; Dalessandro, E.; Ferraro, F. R.; Lanzoni, B; Possenti, A; Burgay, M; Sabbi, E.

    2012-01-01

    We have used deep V and R images acquired at the ESO Very Large Telescope to identify the optical companion to the binary pulsar PSR J0610-2100, one of the black-widow millisecond pulsars recently detected by the Fermi Gamma-ray Telescope in the Galactic plane. We found a faint star (V~26.7) nearly coincident (\\delta r ~0".28) with the pulsar nominal position. This star is visible only in half of the available images, while it disappears in the deepest ones (those acquired under the best seei...

  6. Interstellar scintillations of PSR B1919+21: space-ground interferometry

    CERN Document Server

    Shishov, V I; Gwinn, C R; Andrianov, A S; Popov, M V; Rudnitskiy, A G; Soglasnov, V A

    2016-01-01

    We carried out observations of pulsar PSR B1919+21 at 324 MHz to study the distribution of interstellar plasma in the direction of this pulsar. We used the RadioAstron (RA) space radiotelescope together with two ground telescopes: Westerbork (WB) and Green Bank (GB). The maximum baseline projection for the space-ground interferometer was 60000 km. We show that interstellar scintillation of this pulsar consists of two components: diffractive scintillations from inhomogeneities in a layer of turbulent plasma at a distance $z_{1} = 440$ pc from the observer; and weak scintillations from a screen located near the observer at $z_{2} = 0.13$ pc. Furthermore, in the direction to the pulsar we detected a prism that deflects radiation, leading to a shift of observed source position. We show that the influence of the ionosphere can be ignored for the space-ground baseline. Analysis of the spatial coherence function for the space-ground baseline (RA-GB) yielded the scattering angle in the observer plane: $\\theta_{scat}$...

  7. Highly-Magnetized Pulsars and Integral

    CERN Document Server

    Baring, M G; Baring, Matthew G.; Harding, Alice K.

    1998-01-01

    The complete absence of radio pulsars with periods exceeding a few seconds has lead to the popular notion of the existence of a high period death line. We have recently postulated the existence of another radio quiescence boundary at high magnetic fields ($B\\gtrsim 4\\times 10^{13}$G) in the upper portion of the period-period derivative diagram, a domain where no radio pulsars are observed. The origin of this high B boundary is also due to the suppression of magnetic pair creation, $\\gamma\\to e^{\\pm}$, but mainly because of competition with the exotic QED process of magnetic photon splitting, $\\gamma\\to\\gamma\\gamma$, coupled with ground state pair creation. This mechanism could also explain the low spectral cutoff energy of the gamma-ray pulsar PSR1509-58, which lies near the high B death-line. In this paper, we summarize the hypothesis of this new ``death line,'' and discuss some subtleties of pair suppression that relate to photon polarization and positronium formation. We identify several ways in which Inte...

  8. Multiwavelength analysis of four millisecond pulsars

    Science.gov (United States)

    Guillemot, L.; Cognard, I.; Johnson, T. J.; Venter, C.; Harding, A. K.

    2011-08-01

    Radio timing observations of millisecond pulsars (MSPs) in support of Fermi LAT observations of the gamma-ray sky enhance the sensitivity of high-energy pulsation searches. With contemporaneous ephemerides we have detected gamma-ray pulsations from PSR B1937+21, the first MSP ever discovered, and B1957+20, the first known black-widow system. The two MSPs share a number of properties: they are energetic and distant compared to other gamma-ray MSPs, and both of them exhibit aligned radio and gamma-ray emission peaks, indicating co-located emission regions in the outer magnetosphere of the pulsars. However, radio observations are also crucial for revealing MSPs in Fermi unassociated sources. In a search for radio pulsations at the position of such unassociated sources, the Nançay Radio Telescope discovered two MSPs, PSRs J2017+0603 and J2302+4442, increasing the sample of known Galactic disk MSPs. Subsequent radio timing observations led to the detection of gamma-ray pulsations from these two MSPs as well. We describe multiwavelength timing and spectral analysis of these four pulsars, and the modeling of their gamma-ray light curves in the context of theoretical models.

  9. MeV Pulsars: Modeling Spectra and Polarization

    Science.gov (United States)

    Kust Harding, Alice; Kalapotharakos, Constantinos

    2017-08-01

    A sub-population of energetic rotation-powered pulsars show high fluxes of pulsed non-thermal hard X-ray emission. While this ‘MeV pulsar’ population includes some radio-loud pulsars like the Crab and PSR B1509-58, a significant number have no detected radio or GeV emission, a mystery since gamma-ray emission is a common characteristic of pulsars with high spin-down power. Their steeply rising hard X-ray spectral energy distributions (SEDs) suggest peaks at 0.1 - 1 MeV but they have not been detected above 200 keV. Several upcoming and planned telescopes may shed light on the MeV pulsars. The Neutron star Interior Composition ExploreR (NICER) will observe pulsars in the 0.2 - 12 keV band and may discover additional MeV pulsars. The All-Sky Medium-Energy Gamma-Ray Observatory (AMEGO), in a study phase, can detect emission above 0.2 MeV and polarization in the 0.2 - 10 MeV band. We present a model for the spectrum and polarization of MeV pulsars where the X-ray emission comes from electron-positron pairs radiating in the outer magnetosphere and current sheet. This model predicts that the peak of the SED increases with surface magnetic field strength if the pairs are produced in polar cap cascades. For small inclination angles, viewing at large angles to the rotation axis can miss both the radio pulse and the GeV pulse from particles accelerating near the current sheet. Characterizing the emission and geometry of MeV pulsars can thus provide clues to the source of pairs and acceleration in the magnetosphere.

  10. Gamma-ray emission from PSR J0007+7303 using 7 years of Fermi Large Area Telescope observations

    CERN Document Server

    Li, Jian; Wilhelmi, Emma de Ona; Rea, Nanda; Martin, Jonatan

    2016-01-01

    Based on more than seven years of Fermi Large Area Telescope (LAT) Pass 8 data, we report on a detailed analysis of the bright gamma-ray pulsar (PSR) J0007+7303. We confirm that PSR J0007+7303 is significantly detected as a point source also during the off-peak phases with a TS value of 262 ($\\sim$ 16 $\\sigma$). In the description of PSR J0007+7303 off-peak spectrum, a power law with an exponential cutoff at 2.7$\\pm$1.2$\\pm$1.3 GeV (the first/second uncertainties correspond to statistical/systematic errors) is preferred over a single power law at a level of 3.5 $\\sigma$. The possible existence of a cutoff hints at a magnetospheric origin of the emission. In addition, no extended gamma-ray emission is detected compatible with either the supernova remnant (CTA 1) or the very high energy (> 100 GeV) pulsar wind nebula. A flux upper limit of 6.5$\\times$10$^{-12}$ erg cm$^{-2}$ s$^{-1}$ in the 10-300 GeV energy range is reported, for an extended source assuming the morphology of the VERITAS detection. During on-pe...

  11. A note on the discovery of a 2M⊙ pulsar

    Institute of Scientific and Technical Information of China (English)

    Xiao-Yu Lai; Ren-Xin Xu

    2011-01-01

    It is conventionally thought that the state equation of dense matter softens and thus cannot result in high maximum mass if pulsars are quark stars and that a recently discovered 2M⊙ pulsar (PSR J1614-2230) may make pulsars unlikely to be quark stars.However, this standard point of view would be revisited and updated if quark clustering could occur in cold quark matter because of the strong coupling between quarks at realistic baryon densities in compact stars.It can be argued that the state equation of clustered quark matter stiffens to support compact stars with maximum mass Mmax > 2M⊙.In this brief note, it is demonstrated that large parameter space ranges are allowed for Mmax > 2M⊙ in a Lennard-Jones model of clustered quark matter and the newly measured highest mass of PSR J1614-2230 would be meaningful for constraining the number of quarks inside a single quark-cluster to be Nq (<) 103.

  12. Pulsar bi-drifting: implications for polar cap geometry

    CERN Document Server

    Wright, Geoff

    2016-01-01

    For many years it has been considered puzzling how pulsar radio emission, supposedly created by a circulating carousel of sub-beams, can produce the driftbands demonstrated by PSR J0815+09, and more recently PSR B1839-04, which simultaneously drift in opposing directions. Here we suggest that the carousels of these pulsars, and hence their beams, are not circular but elliptical with axes tilted with respect to the fiducial plane. We show that certain relatively unusual lines of sight can cause bi-drifting to be observed, and a simulation of the two known exemplars is presented. Although bi-drifting is rare, non-circular beams may be common among pulsars and reveal themselves by having profile centroids displaced from the fiducial plane identified by polarisation position angle swings. They may also result in profiles with asymmetric and frequency-dependent component evolution. It is further suggested that the carousels may change their tilt by specific amounts and later reverse them. This may occur suddenly, ...

  13. Timing of five millisecond pulsars discovered in the PALFA survey

    CERN Document Server

    Scholz, P; Lyne, A G; Stappers, B W; Bogdanov, S; Cordes, J M; Crawford, F; Ferdman, R D; Freire, P C C; Hessels, J W T; Lorimer, D R; Stairs, I H; Allen, B; Brazier, A; Camilo, F; Cardoso, R F; Chatterjee, S; Deneva, J S; Jenet, F A; Karako-Argaman, C; Knispel, B; Lazarus, P; Lee, K J; van Leeuwen, J; Lynch, R; Madsen, E C; McLaughlin, M A; Ransom, S M; Siemens, X; Spitler, L G; Stovall, K; Swiggum, J K; Venkataraman, A; Zhu, W W

    2015-01-01

    We present the discovery of five millisecond pulsars (MSPs) from the PALFA Galactic plane survey using Arecibo. Four of these (PSRs J0557+1551, J1850+0244, J1902+0300, and J1943+2210) are binary pulsars whose companions are likely white dwarfs, and one (PSR J1905+0453) is isolated. Phase-coherent timing solutions, ranging from $\\sim$1 to $\\sim$3 years in length, and based on observations from the Jodrell Bank and Arecibo telescopes, provide precise determinations of spin, orbital, and astrometric parameters. All five pulsars have large dispersion measures ($>100$ pc cm$^{-3}$, within the top 20% of all known Galactic field MSPs) and are faint (1.4 GHz flux density < 0.1 mJy, within the faintest 5% of all known Galactic field MSPs), illustrating PALFA's ability to find increasingly faint, distant MSPs in the Galactic plane. In particular, PSR J1850+0244 has a dispersion measure of 540 pc cm$^{-3}$, the highest of all known MSPs. Such distant, faint MSPs are important input for accurately modeling the total ...

  14. TIMING OF FIVE MILLISECOND PULSARS DISCOVERED IN THE PALFA SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, P.; Kaspi, V. M.; Ferdman, R. D.; Karako-Argaman, C. [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Lyne, A. G.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Bogdanov, S.; Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Cordes, J. M.; Brazier, A.; Chatterjee, S. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Crawford, F. [Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003 (United States); Freire, P. C. C. [Max-Planck-Institut für Radioastronomie, D-53121 Bonn (Germany); Hessels, J. W. T. [ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990-AA Dwingeloo (Netherlands); Lorimer, D. R.; Cardoso, R. F. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Allen, B. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Deneva, J. S. [Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Jenet, F. A., E-mail: pscholz@physics.mcgill.ca [Center for Gravitational Wave Astronomy, University of Texas at Brownsville, TX 78520 (United States); and others

    2015-02-20

    We present the discovery of five millisecond pulsars (MSPs) from the PALFA Galactic plane survey using Arecibo. Four of these (PSRs J0557+1551, J1850+0244, J1902+0300, and J1943+2210) are binary pulsars whose companions are likely white dwarfs, and one (PSR J1905+0453) is isolated. Phase-coherent timing solutions, ranging from ∼1 to ∼3 yr in length, and based on observations from the Jodrell Bank and Arecibo telescopes, provide precise determinations of spin, orbital, and astrometric parameters. All five pulsars have large dispersion measures (>100 pc cm{sup –3}, within the top 20% of all known Galactic field MSPs) and are faint (1.4 GHz flux density ≲0.1 mJy, within the faintest 5% of all known Galactic field MSPs), illustrating PALFA's ability to find increasingly faint, distant MSPs in the Galactic plane. In particular, PSR J1850+0244 has a dispersion measure of 540 pc cm{sup –3}, the highest of all known MSPs. Such distant, faint MSPs are important input for accurately modeling the total Galactic MSP population.

  15. Gamma-ray flare activity from PSR B1259-63 during 2014 periastron passage and comparison to its 2010 passage

    CERN Document Server

    Caliandro, G A; Li, J; Scargle, J D; Torres, D F; Wood, K S; Chernyakova, M

    2015-01-01

    PSR B1259-63/LS 2883 is a gamma-ray binary system containing a radio pulsar in a highly elliptical ~3.4-year orbit around a Be star. In its 2010 periastron passage, multiwavelength emission from radio to TeV was observed, as well as an unexpected GeV flare measured by the Fermi Large Area Telescope (LAT). Here, we report the results of LAT monitoring of PSR B1259-63 during its most recent 2014 periastron passage. We compare the gamma-ray behavior in this periastron with the former in 2010 and find that PSR B1259-63 shows a recurrent GeV flare. The similarities and differences in the phenomenology of both periastron passages are discussed.

  16. A 6.5-GHz Multibeam Pulsar Survey

    CERN Document Server

    Bates, S D; Lorimer, D R; Kramer, M; Possenti, A; Burgay, M; Stappers, B; Keith, M J; Lyne, A; Bailes, M; McLaughlin, M A; O'Brien, J T; Hobbs, G

    2010-01-01

    A survey of the Galactic plane in the region $-60\\degree \\leq l \\leq 30\\degree$, $|b| \\leq 0.25\\degree$ was carried out using the seven-beam Parkes Methanol Multibeam (MMB) receiver, which operates at a frequency of 6.5 GHz. Three pulsars were discovered, and 16 previously known pulsars detected. In this paper we present two previously-unpublished discoveries, both with extremely high dispersion measures, one of which is very close, in angular distance, to the Galactic centre. The survey data also contain the first known detection, at radio frequencies, of the radio magnetar PSR J1550-5418. Our survey observation was made 46 days prior to that previously published and places constraints on the beginning of pulsed radio emission from the source. The detection of only three previously undiscovered pulsars argues that there are few pulsars in the direction of the inner Galaxy whose flux density spectrum is governed by a flat power law. However, these pulsars would be likely to remain undetected at lower frequenc...

  17. X-ray states of redback millisecond pulsars

    CERN Document Server

    Linares, Manuel

    2014-01-01

    Compact binary millisecond pulsars with main-sequence donors, often referred to as "redbacks", constitute the long-sought link between low-mass X-ray binaries and millisecond radio pulsars, and offer a unique probe of the interaction between pulsar winds and accretion flows. We present a systematic study of eight nearby redbacks, using more than 100 observations obtained with Swift's X-ray Telescope. We distinguish between three main states: pulsar, disk and outburst states. We find X-ray mode switching in the disk state of PSR J1023+0038 and XSS J12270-4859, similar to what was found in the other redback which showed evidence for accretion: rapid, recurrent changes in X-ray luminosity (0.5-10 keV, L$_\\mathrm{X}$), between [6-9]$\\times$10$^{32}$ erg s$^{-1}$ (disk-passive state) and [3-5]$\\times$10$^{33}$ erg s$^{-1}$ (disk-active state). This strongly suggests that mode switching $-$which has not been observed in quiescent low-mass X-ray binaries$-$ is universal among redback millisecond pulsars in the disk ...

  18. EINSTEIN@HOME DISCOVERY OF FOUR YOUNG GAMMA-RAY PULSARS IN FERMI LAT DATA

    Energy Technology Data Exchange (ETDEWEB)

    Pletsch, H. J.; Allen, B.; Aulbert, C.; Bock, O.; Eggenstein, H. B.; Fehrmann, H.; Machenschalk, B.; Papa, M. A. [Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut), D-30167 Hannover (Germany); Guillemot, L.; Champion, D. J.; Karuppusamy, R.; Kramer, M.; Ng, C. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Anderson, D. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Hammer, D.; Siemens, X. [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI 53201 (United States); Keith, M. [CSIRO Astronomy and Space Science, Australia Telescope National Facility (Australia); Ray, P. S., E-mail: holger.pletsch@aei.mpg.de, E-mail: lucas.guillemot@cnrs-orleans.fr [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)

    2013-12-10

    We report the discovery of four gamma-ray pulsars, detected in computing-intensive blind searches of data from the Fermi Large Area Telescope (LAT). The pulsars were found using a novel search approach, combining volunteer distributed computing via Einstein@Home and methods originally developed in gravitational-wave astronomy. The pulsars PSRs J0554+3107, J1422–6138, J1522–5735, and J1932+1916 are young and energetic, with characteristic ages between 35 and 56 kyr and spin-down powers in the range 6 × 10{sup 34}—10{sup 36} erg s{sup –1}. They are located in the Galactic plane and have rotation rates of less than 10 Hz, among which the 2.1 Hz spin frequency of PSR J0554+3107 is the slowest of any known gamma-ray pulsar. For two of the new pulsars, we find supernova remnants coincident on the sky and discuss the plausibility of such associations. Deep radio follow-up observations found no pulsations, suggesting that all four pulsars are radio-quiet as viewed from Earth. These discoveries, the first gamma-ray pulsars found by volunteer computing, motivate continued blind pulsar searches of the many other unidentified LAT gamma-ray sources.

  19. Einstein@Home Discovery of Four Young Gamma-Ray Pulsars in Fermi LAT Data

    Science.gov (United States)

    Pletsch, H. J.; Guillemot, L.; Allen, B.; Anderson, D.; Aulbert, C.; Bock, O.; Champion, D. J.; Eggenstein, H. B.; Fehrmann, H.; Hammer, D.; Karuppusamy, R.; Keith, M.; Kramer, M.; Machenschalk, B.; Ng, C.; Papa, M. A.; Ray, P. S.; Siemens, X.

    2013-12-01

    We report the discovery of four gamma-ray pulsars, detected in computing-intensive blind searches of data from the Fermi Large Area Telescope (LAT). The pulsars were found using a novel search approach, combining volunteer distributed computing via Einstein@Home and methods originally developed in gravitational-wave astronomy. The pulsars PSRs J0554+3107, J1422-6138, J1522-5735, and J1932+1916 are young and energetic, with characteristic ages between 35 and 56 kyr and spin-down powers in the range 6 × 1034—1036 erg s-1. They are located in the Galactic plane and have rotation rates of less than 10 Hz, among which the 2.1 Hz spin frequency of PSR J0554+3107 is the slowest of any known gamma-ray pulsar. For two of the new pulsars, we find supernova remnants coincident on the sky and discuss the plausibility of such associations. Deep radio follow-up observations found no pulsations, suggesting that all four pulsars are radio-quiet as viewed from Earth. These discoveries, the first gamma-ray pulsars found by volunteer computing, motivate continued blind pulsar searches of the many other unidentified LAT gamma-ray sources.

  20. A New, Low Braking Index For the LMC Pulsar B0540-69

    Science.gov (United States)

    Marshall, Francis E.; Guillemot, Lucas; Kust Harding, Alice; Martin, Pierrick; Smith, David A.

    2017-01-01

    We report the results of a 16 month monitoring campaign using the Swift satellite of PSR B0540-69, a young pulsar in the Large Magellanic Cloud. Phase connection was maintained throughout the campaign so that a reliable ephemeris could be determined, and the length of the campaign is adequate to accurately determine the spin frequency and its first and second derivatives. The braking index n is 0.031 ± 0.013 (90% confidence), a value much lower than previously reported for B0540-69 and almost all other young pulsars. The monitoring campaign is continuing, and the pulsar remains in its high spin-down state. We use data from the extensive monitoring campaign with RXTE to show that timing noise is unlikely to significantly affect the measurement. This is the first measurement of the braking index in the pulsar's recently discovered high spin-down state. We discuss possible mechanisms for producing the low braking index.

  1. The High Time Resolution Universe Pulsar Survey X: Discovery of four millisecond pulsars and updated timing solutions of a further 12

    CERN Document Server

    Ng, C; Bates, S D; Bhat, N D R; Burgay, M; Burke-Spolaor, S; Champion, D J; Coster, P; Johnston, S; Keith, M J; Kramer, M; Levin, L; Petroff, E; Possenti, A; Stappers, B W; van Straten, W; Thornton, D; Tiburzi, C; Bassa, C G; Freire, P C C; Guillemot, L; Lyne, A G; Tauris, T M; Shannon, R M; Wex, N

    2014-01-01

    We report on the discovery of four millisecond pulsars (MSPs) in the High Time Resolution Universe (HTRU) pulsar survey being conducted at the Parkes 64-m radio telescope. All four MSPs are in binary systems and are likely to have white dwarf companions. In addition, we present updated timing solutions for 12 previously published HTRU MSPs, revealing new observational parameters such as five proper motion measurements and significant temporal dispersion measure variations in PSR J1017-7156. We discuss the case of PSR J1801-3210, which shows no significant period derivative after four years of timing data. Our best-fit solution shows a period derivative of the order of $10^{-23}$, an extremely small number compared to that of a typical MSP. However, it is likely that the pulsar lies beyond the Galactic Centre, and an unremarkable intrinsic period derivative is reduced to close to zero by the Galactic potential acceleration. Furthermore, we highlight the potential to employ PSR J1801-3210 in the strong equivale...

  2. The optical companion to the binary millisecond pulsar J1824-2452H in the globular cluster M28

    CERN Document Server

    Pallanca, C; Ferraro, F R; Lanzoni, B; Rood, R T; Possenti, A; D'Amico, N; Freire, P C; Stairs, I; Ransom, S M; Begin, S

    2010-01-01

    We report on the optical identification of the companion star to the eclipsing millisecond pulsar PSR J1824-2452H in the galactic globular cluster M28 (NGC 6626). This star is at only 0.2" from the nominal position of the pulsar and it shows optical variability (~ 0.25 mag) that nicely correlates with the pulsar orbital period. It is located on the blue side of the cluster main sequence, ~1.5 mag fainter than the turn-off point. The observed light curve shows two distinct and asymmetric minima, suggesting that the companion star is suffering tidal distortion from the pulsar. This discovery increases the number of non-degenerate MSP companions optically identified so far in globular clusters (4 out of 7), suggesting that these systems could be a common outcome of the pulsar recycling process, at least in dense environments where they can be originated by exchange interactions.

  3. HIGH-FIDELITY RADIO ASTRONOMICAL POLARIMETRY USING A MILLISECOND PULSAR AS A POLARIZED REFERENCE SOURCE

    Energy Technology Data Exchange (ETDEWEB)

    Van Straten, W., E-mail: vanstraten.willem@gmail.com [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122 (Australia)

    2013-01-15

    A new method of polarimetric calibration is presented in which the instrumental response is derived from regular observations of PSR J0437-4715 based on the assumption that the mean polarized emission from this millisecond pulsar remains constant over time. The technique is applicable to any experiment in which high-fidelity polarimetry is required over long timescales; it is demonstrated by calibrating 7.2 years of high-precision timing observations of PSR J1022+1001 made at the Parkes Observatory. Application of the new technique followed by arrival time estimation using matrix template matching yields post-fit residuals with an uncertainty-weighted standard deviation of 880 ns, two times smaller than that of arrival time residuals obtained via conventional methods of calibration and arrival time estimation. The precision achieved by this experiment yields the first significant measurements of the secular variation of the projected semimajor axis, the precession of periastron, and the Shapiro delay; it also places PSR J1022+1001 among the 10 best pulsars regularly observed as part of the Parkes Pulsar Timing Array (PPTA) project. It is shown that the timing accuracy of a large fraction of the pulsars in the PPTA is currently limited by the systematic timing error due to instrumental polarization artifacts. More importantly, long-term variations of systematic error are correlated between different pulsars, which adversely affects the primary objectives of any pulsar timing array experiment. These limitations may be overcome by adopting the techniques presented in this work, which relax the demand for instrumental polarization purity and thereby have the potential to reduce the development cost of next-generation telescopes such as the Square Kilometre Array.

  4. Fermi-LAT Constraints on the Pulsar Wind Nebula Nature of HESS J1857+026

    Science.gov (United States)

    Rousseau, R.; Grondin, M.-H.; VanEtten, A.; Lemoine-Goumard, M.; Bogdanov, S.; Hessels, J. W. T.; Kaspi, V. M.; Arzoumanian, Z.; Camilo, F.; Casandjian, J. M.; Espinoza, C. M.; Johnston, S.; Lyne, A. G.; Smith, D. A.; Stappers, B. W.; Caliandro, G. A.

    2012-01-01

    Since its launch, the Fermi satellite has firmly identified 5 pulsar wind nebulae plus a large number of candidates, all powered by young and energetic pulsars. HESS J1857+026 is a spatially extended gamma-ray source detected by H.E.S.S. and classified as a possible pulsar wind nebula candidate powered by PSR J1856+0245. Aims. We search for -ray pulsations from PSR J1856+0245 and explore the characteristics of its associated pulsar wind nebula. Methods. Using a rotational ephemeris obtained from the Lovell telescope at Jodrell Bank Observatory at 1.5 GHz, we phase.fold 36 months of gamma-ray data acquired by the Large Area Telescope (LAT) aboard Fermi. We also perform a complete gamma-ray spectral and morphological analysis. Results. No pulsation was detected from PSR J1856+0245. However, significant emission is detected at a position coincident with the TeV source HESS J1857+026. The gamma-ray spectrum is well described by a simple power law with a spectral index of Gamma = 1.53 +/- 0.11(sub stat) +/- 0.55(sub syst) and an energy flux of G(0.1 C100 GeV) = (2.71 +/- 0.52(sub stat) +/- 1.51(sub syst) X 10(exp -11) ergs/ sq cm/s. This implies a gamma.ray efficiency of approx 5 %, assuming a distance of 9 kpc, the gamma-ray luminosity of L(sub gamma) (sub PWN) (0.1 C100 GeV) = (2.5 +/- 0.5(sub stat) +/- 1.5(sub syst)) X 10(exp 35)(d/(9kpc))(exp 2) ergs/s and E-dot = 4.6 X 10(exp 36) erg /s, in the range expected for pulsar wind nebulae. Detailed multi-wavelength modeling provides new constraints on its pulsar wind nebula nature.

  5. Triple Pulsar Tests Mass Triplets

    CERN Document Server

    Shao, Lijing

    2016-01-01

    Three conceptually different masses appear in equations of motion for objects under gravity, namely, inertial mass, $m_{\\cal I}$, passive gravitational mass, $m_{\\cal P}$, and active gravitational mass, $m_{\\cal A}$. It is assumed that, for any objects, $m_{\\cal I} = m_{\\cal P} = m_{\\cal A}$ in Newtonian gravity, and $m_{\\cal I} = m_{\\cal P}$ in Einsteinian gravity, oblivious to objects' sophisticated internal structure. Empirical examination of the equivalence probes deep into gravity theories. We propose new tests based on pulsar timing of the stellar triple system, PSR J0337+1715. Various machine-precision three-body simulations are performed, from which, equivalence-violating parameters are extracted with Markov chain Monte Carlo sampling that takes full correlations into account. We show that the difference in masses can be probed to $3\\times10^{-8}$, improving the post-Newtonian constraints of strong equivalence principle by $10^3$--$10^6$. The test of $m_{\\cal P}=m_{\\cal A}$ presents the first test of ...

  6. Precession of the Orbital Plane of Binary Pulsars and Significant Variabilities

    Institute of Scientific and Technical Information of China (English)

    Bi-Ping Gong

    2005-01-01

    There are two ways of expressing the precession of orbital plane of a binary pulsar system, given by Barker & O'Connell, Apostolatos et al. and Kidder, respectively. We point out that these two ways actually come from the same Lagrangian under different degrees of freedom. Damour & Schafer and Wex & Kopeikin applied Barker & O'Connell's orbital precession velocity in pulsar timing measurement. This paper applies Apostolatos et al.'s and Kidder's orbital precession velocity. We show that Damour & Schafer's treatment corresponds to negligible Spin-Orbit induced precession of periastron, while Wex & Kopeikin and this paper both found significant (but not equivalent) effects. The observational data of two typical binary pulsars, PSR J2051-0827 and PSR J1713+0747, apparently support a significant Spin-Orbit coupling effect. Specific binary pulsars with orbital plane nearly edge on could discriminate between Wex & Kopeikin and this paper: if the orbital period derivative of the double-pulsar system PSRs J0737-3039 A and B, with orbital inclination angle i =87.7+17 -29 deg, is much larger than that of the gravitational radiation induced one, then the expression in this paper is supported, otherwise Wex & Kopeikin's is supported.

  7. The High Time Resolution Universe Survey VI: An Artificial Neural Network and Timing of 75 Pulsars

    CERN Document Server

    Bates, S D; Barsdell, B R; Bhat, N D R; Burgay, M; Burke-Spolaor, S; Champion, D J; Coster, P; D'Amico, N; Jameson, A; Johnston, S; Keith, M J; Kramer, M; Levin, L; Lyne, A; Milia, S; Ng, C; Nietner, C; Possenti, A; Stappers, B; Thornton, D; van Straten, W

    2012-01-01

    We present 75 pulsars discovered in the mid-latitude portion of the High Time Resolution Universe survey, 54 of which have full timing solutions. All the pulsars have spin periods greater than 100 ms, and none of those with timing solutions are in binaries. Two display particularly interesting behaviour; PSR J1054-5944 is found to be an intermittent pulsar, and PSR J1809-0119 has glitched twice since its discovery. In the second half of the paper we discuss the development and application of an artificial neural network in the data-processing pipeline for the survey. We discuss the tests that were used to generate scores and find that our neural network was able to reject over 99% of the candidates produced in the data processing, and able to blindly detect 85% of pulsars. We suggest that improvements to the accuracy should be possible if further care is taken when training an artificial neural network; for example ensuring that a representative sample of the pulsar population is used during the training proc...

  8. Two long-term intermittent pulsars discovered in the PALFA Survey

    CERN Document Server

    Lyne, A G; Freire, P C C; Hessels, J W T; Kaspi, V M; Allen, B; Bogdanov, S; Brazier, A; Camilo, F; Cardoso, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J S; Ferdman, R D; Jenet, F A; Knispel, B; Lazarus, P; van Leeuwen, J; Lorimer, D R; Lynch, R; Madsen, E; McLaughlin, M A; Parent, E; Patel, C; Ransom, S M; Scholz, P; Seymour, A; Siemens, X; Spitler, L G; Stairs, I H; Stovall, K; Swiggum, J; Wharton, R S; Zhu, W W

    2016-01-01

    We report the discovery of two long-term intermittent radio pulsars in the ongoing Arecibo PALFA pulsar survey. Following discovery with the Arecibo Telescope, extended observations of these pulsars over several years at Jodrell Bank Observatory have revealed the details of their rotation and radiation properties. PSRs J1910+0517 and J1929+1357 show long-term extreme bi-modal intermittency, switching between active (ON) and inactive (OFF) emission states and indicating the presence of a large, hitherto unrecognised, underlying population of such objects. For PSR J1929+1357, the initial duty cycle was fON=0.008, but two years later this changed, quite abruptly, to fON=0.16. This is the first time that a significant evolution in the activity of an intermittent pulsar has been seen and we show that the spin-down rate of the pulsar is proportional to the activity. The spin-down rate of PSR J1929+1357 is increased by a factor of 1.8 when it is in active mode, similar to the increase seen in the other three known l...

  9. The mode switching of PSR B2020+28

    CERN Document Server

    Wen, Z G; Yan, W M; Yuan, J P; Liu, Z Y; Chen, M Z; Chen, J L

    2016-01-01

    This paper reports on polarimetric radiation properties based on the switching modes of normal PSR B2020+28 by analysing the data acquired from the Nanshan 25-m radio telescope at 1556 MHz. With nearly 8 hours quasi-continuous observation, the data presented some striking and updated phenomena. The change of relative intensity between the leading and trailing components is the predominant feature of mode switching. The intensity ratio between the leading and trailing components are measured for the individual profiles averaged over 30 seconds. It is found that there is an excess of high ratios over the normal distribution, which indicates that two modes exist in the pulsar. The distribution of abnormal mode has a narrower width indicating that the abnormal mode is more stable than the normal mode. A total of 76 mode switching events are detected in our data. It spends 89\\% in the normal mode and 11\\% in the abnormal mode. The intrinsic distributions of mode timescales are constrained with power-law distributi...

  10. The mode switching of PSR B2020+28

    Science.gov (United States)

    Wen, Z. G.; Wang, N.; Yan, W. M.; Yuan, J. P.; Liu, Z. Y.; Chen, M. Z.; Chen, J. L.

    2016-08-01

    This paper reports on polarimetric radiation properties based on the switching modes of normal PSR B2020+28 by analyzing the data acquired from the Nanshan 25-m radio telescope at 1556 MHz. With nearly 8 hours quasi-continuous observation, the data presented some striking and updated phenomena. The change of relative intensity between the leading and trailing components is the predominant feature of mode switching. The intensity ratio between the leading and trailing components are measured for the individual profiles averaged over 30 seconds. It is found that there is an excess of high ratios over the normal distribution, which indicates that two modes exist in the pulsar. The distribution of abnormal mode has a narrower width indicating that the abnormal mode is more stable than the normal mode. A total of 76 mode switching events are detected in our data. It spends 89 % in the normal mode and 11 % in the abnormal mode. The intrinsic distributions of mode timescales are constrained with power-law distributions. The significant difference in the index of the duration distribution between normal and abnormal modes possibly indicates that the timescale for the abnormal mode to get stable is shorter than that for the normal mode. The frequent switching between both modes may indicate that the oscillations between different magnetospheric states are rapid.

  11. Measurement of Gravitational Spin-Orbit Coupling in a Binary Pulsar System

    Science.gov (United States)

    Stairs, I. H.; Thorsett. S. E.; Arzoumanian, Z.

    2004-01-01

    In relativistic gravity, a spinning pulsar will precess as it orbits a compact companion star. We have measured the effect of such precession on the average shape and polarization of the radiation from PSR B1534+12. We have also detected, with limited precision, special-relativistic aberration of the revolving pulsar beam due to orbital motion. Our observations fix the system geometry, including the misalignment between the spin and orbital angular momenta, and yield a measurement of the precession timescale consistent with the predictions of General Relativity.

  12. The Braking Index of a Radio-quiet Gamma-ray Pulsar

    OpenAIRE

    Clark, C J; Pletsch, H. J.; Wu, J.; Guillemot, L.; Camilo, F.; Johnson, T. J.; Kerr, M.; Allen, B.; Aulbert, C.; Beer, C; Bock, O.; Cuéllar, A.; Eggenstein, H. B.; Fehrmann, H.; Kramer, M.

    2016-01-01

    We report the discovery and timing measurements of PSR J1208-6238, a young and highly magnetized gamma-ray pulsar, with a spin period of 440 ms. The pulsar was discovered in gamma-ray photon data from the Fermi Large Area Telescope (LAT) during a blind-search survey of unidentified LAT sources, running on the distributed volunteer computing system Einstein@Home. No radio pulsations were detected in dedicated follow-up searches with the Parkes radio telescope, with a flux density upper limit a...

  13. HESS Observations of Pulsar Wind Nebulae

    CERN Document Server

    De Jager, O C

    2006-01-01

    The high resolution capabilities of the High Energy Stereoscopic System (HESS) introduced a new era in Gamma-Ray Astronomy, and opens a new window on pulsar wind nebula (PWN) research. A rotationally induced jet (associated with PSR B1509-58) is resolved for the first time in gamma-rays, allowing us to trace the particle transport directly, without having the complicating effect of spatially varying field distributions on the synchrotron emissivity. For PWN older or more extended than Crab (i.e. those with lower field strengths), HESS also reveals the properties of electrons contributing to the EUV/soft X-ray synchrotron bands, whereas EUV/soft X-rays suffer from severe interstellar absorption effects. Finally, HESS morphological studies of evovled PWN also allow us to directly measure the effects of assymetric reverse shock interactions due to SNR forward shock expansion into the inhomogeneous interstellar medium.

  14. Pulse profile stability of the Crab pulsar

    CERN Document Server

    Jain, Chetana

    2011-01-01

    We present an X-ray timing analysis of the Crab pulsar, PSR B0531+21, using the archival RXTE data. We have investigated the stability of the Crab pulse profile, in soft (2-20 keV) and hard (30-100 keV) X-ray energies, over the last decade of RXTE operation. The analysis includes measurement of the separation between the two pulse peaks; and intensity and the widths of the two peaks. We did not find any significant time dependency in the pulse shape. The two peaks are stable in phase, intensity and widths, for the last ten years. The first pulse is relatively stronger at soft X-rays. The first pulse peak is narrower than the second peak, in both, soft- and hard X-ray energies. Both the peaks show a slow rise and a steeper fall. The ratio of the pulsed photons in the two peaks is also constant in time.

  15. Radio Timing and Optical Photometry of the Black Widow System PSR J1953+1846A in the Globular Cluster M71

    CERN Document Server

    Cadelano, M; Ferraro, F R; Stairs, I; Ransom, S M; Dalessandro, E; Lanzoni, B; Hessels, J W T; Freire, P C C

    2015-01-01

    We report on the determination of the astrometric, spin and orbital parameters for PSR J1953+1846A, a "black widow" binary millisecond pulsar in the globular cluster M71. By using the accurate position and orbital parameters obtained from radio timing, we identified the optical companion in ACS/Hubble Space Telescope images. It turns out to be a faint (m_F606W>=24, m_F814W>=23) and variable star located at only ~0.06" from the pulsar timing position. The light curve shows a maximum at the pulsar inferior conjunction and a minimum at the pulsar superior conjunction, thus confirming the association with the system. The shape of the optical modulation suggests that the companion star is heated, likely by the pulsar wind. The comparison with the X-ray light curve possibly suggests the presence of an intra-binary shock due to the interaction between the pulsar wind and the material released by the companion. This is the second identification (after COM-M5C) of an optical companion to a black widow pulsar in a glob...

  16. Radio timing and optical photometry of the black widow system PSR J1518+0204C in the globular cluster M5

    Energy Technology Data Exchange (ETDEWEB)

    Pallanca, C.; Ferraro, F. R.; Dalessandro, E.; Lanzoni, B. [Dipartimento di Fisica e Astronomia, Università di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy); Ransom, S. M. [National Radio Astronomy Observatory (NRAO), 520 Edgemont Road, Charlottesville, VA 22901 (United States); Hessels, J. W. T. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo (Netherlands); Stairs, I. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T1Z1 (Canada); Freire, P. C. C. [Max-Planck-Institute für Radioastronomie, D-53121 Bonn (Germany)

    2014-11-01

    We report on the determination of astrometric, spin, and orbital parameters for PSR J1518+0204C, a 'black widow' binary millisecond pulsar in the globular cluster (GC) M5. The accurate position and orbital parameters obtained from radio timing allowed us to search for the optical companion. By using WFC3/Hubble Space Telescope images, we identified a very faint variable star (m{sub F390W} ≳ 24.8, m{sub F606W} ≳ 24.3, m{sub F814W} ≳ 23.1) located at only 0.''25 from the pulsar's timing position. Due to its strong variability, this star is visible only in a subsample of images. However, the light curve obtained folding the available data with the orbital parameters of the pulsar shows a maximum at the pulsar inferior conjunction and a possible minimum at the pulsar superior conjunction. Furthermore, the shape of the optical modulation indicates a heating process possibly due to the pulsar wind. This is the first identification of an optical companion to a black widow pulsar in the dense stellar environment of a GC.

  17. Radio timing and optical photometry of the black widow system PSR J1518+0204C in the globular cluster M5

    CERN Document Server

    Pallanca, C; Ferraro, F R; Dalessandro, E; Lanzoni, B; Hessels, J W T; Stairs, I; Freire, P C C

    2014-01-01

    We report on the determination of astrometric, spin and orbital parameters for PSR J1518+0204C, a "black widow" binary millisecond pulsar in the globular cluster M5. The accurate position and orbital parameters obtained from radio timing allowed us to search for the optical companion. By using WFC3/HST images we identified a very faint variable star (m_F390W > 24.8, m_F606W > 24.3, m_F814W > 23.1) located at only 0.25" from the pulsar's timing position. Due to its strong variability, this star is visible only in a sub-sample of images. However, the light curve obtained folding the available data with the orbital parameters of the pulsar shows a maximum at the pulsar inferior conjunction and a possible minimum at the pulsar superior conjunction. Furthermore, the shape of the optical modulation indicates a heating process possibly due to the pulsar wind. This is the first identification of an optical companion to a black widow pulsar in the dense stellar environment of a globular cluster.

  18. Fermi pulsar revolution

    CERN Document Server

    Caraveo, Patrizia A

    2010-01-01

    2009 has been an extraordinary year for gamma-ray pulsar astronomy and 2010 promises to be equally good. Not only have we registered an extraordinary increase in the number of pulsars detected in gamma rays, but we have also witnessed the birth of new sub-families: first of all, the radio-quiet gamma pulsars and later an ever growing number of millisecond pulsars, a real surprise. We started with a sample of 7 gamma-ray emitting neutron stars (6 radio pulsars and Geminga) and now the Fermi-LAT harvest encompasses 24 "Geminga-like" new gamma-ray pulsars, a dozen millisecond pulsars and about thirty radio pulsars. Moreover, radio searches targeted to LAT unidentified sources yielded 18 new radio millisecond pulsars, several of which have been already detected also in gamma rays. Thus, currently the family of gamma-ray emitting neutron stars seems to be evenly divided between classical radio pulsars, millisecond pulsars and radio quiet neutron stars.

  19. Discovery of a Radio Bubble Trailing PSR J1015-5719

    Science.gov (United States)

    Ng, C.-Y.

    2016-06-01

    PSR J1015-5719 is a young and energetic pulsar with a characteristic age of 39 kyr and a spin down luminosity of 8.3 x 10^35 erg/s. We report on radio imaging observations of the field made with the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array at 36, 16, 6, and 3 cm. We discovered a highly linearly polarized radio nebula associated with the pulsar. It shows a faint triangular head region centered on the pulsar, followed by a bubble with 40" diameter and a faint tail of ~1' further south. At the pulsar distance of ~5 kpc, the physical size of the bubble seems too small for it to be the parent supernova remnant. We believe that it is more likely to be a pulsar wind nebula (PWN), based on the flat radio spectral index of ~0.15 and high degree of polarization we found. Similar bubbles have been found in other PWNe such as the Guitar Nebula, and it was attributed to instability in the flow. We compare the PWN of J1015 with these cases and discuss the physical environment in the system. The Australia Telescope Compact Array is part of the Australia Telescope National Facility which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. MOST is operated by The University of Sydney with support from the Australian Research Council and the Science Foundation for Physics within the University of Sydney. This work is supported by an ECS grant under HKU 709713P.

  20. Shining Light on Quantum Gravity with Pulsar-Black hole Binaries

    Science.gov (United States)

    Estes, John; Kavic, Michael; Lippert, Matthew; Simonetti, John H.

    2017-03-01

    Pulsars are some of the most accurate clocks found in nature, while black holes offer a unique arena for the study of quantum gravity. As such, pulsar-black hole (PSR-BH) binaries provide ideal astrophysical systems for detecting the effects of quantum gravity. With the success of aLIGO and the advent of instruments like SKA and eLISA, the prospects for the discovery of such PSR-BH binaries are very promising. We argue that PSR-BH binaries can serve as ready-made testing grounds for proposed resolutions to the black hole information paradox. We propose using timing signals from a pulsar beam passing through the region near a black hole event horizon as a probe of quantum gravitational effects. In particular, we demonstrate that fluctuations of the geometry outside a black hole lead to an increase in the measured root mean square deviation of the arrival times of pulsar pulses traveling near the horizon. This allows for a clear observational test of the nonviolent nonlocality proposal for black hole information escape. For a series of pulses traversing the near-horizon region, this model predicts an rms in pulse arrival times of ˜ 30 μ {{s}} for a 3{M}⊙ black hole, ˜ 0.3 {ms} for a 30{M}⊙ black hole, and ˜ 40 {{s}} for Sgr A*. The current precision of pulse time-of-arrival measurements is sufficient to discern these rms fluctuations. This work is intended to motivate observational searches for PSR-BH systems as a means of testing models of quantum gravity.

  1. Interpole Communication in Radio Pulsars and the Resulting Theoretical Challenges

    Science.gov (United States)

    Weltevrede, P.; Wright, G.; Johnston, S.

    2012-12-01

    Here we discuss some recent, and less recent, radio observations that demonstrate an intimate link between the emission generated by opposite magnetic poles of neutron stars. More specifically, there are examples of pulsars which show quasi-periodic brightening of the emission generated by both poles with a time delay which remains fixed on a timescale of at least years. This implies that the opposite magnetic poles do not operate independently of each other, leading to the question about the nature of the communication channel. In the case of PSR B1055-52 this time delay is very large, corresponding to a light travel distance of many times the light cylinder radius. A number of physical models are explored and significant objections can be made to each model. So the communication channel between the magnetic poles of pulsars remains elusive, although its understanding could prove crucial to understanding the large-scale structure of magnetospheres.

  2. The Eccentric Binary Millisecond Pulsar in NGC 1851

    CERN Document Server

    Freire, Paulo C C; Gupta, Yashwant

    2007-01-01

    PSR J0514-4002A is a 5-ms pulsar is located in the globular cluster NGC 1851; it belongs to a highly eccentric (e = 0.888) binary system. It is one of the earliest known examples of a numerous and fast-growing class of eccentric binary MSPs recently discovered in globular clusters. Using the GBT, we have obtained a phase-coherent timing solution for the pulsar, which includes a measurement of the rate of advance of periastron: 0.01289(4) degrees per year, which if due completely to general relativity, implies a total system mass of 2.453(14) solar masses. We also derive m_p 0.96 solar masses. The companion is likely to be a massive white dwarf star.

  3. The identification of the optical companion to the binary millisecond pulsar J0610-2100 in the Galactic field

    CERN Document Server

    Pallanca, C; Dalessandro, E; Ferraro, F R; Lanzoni, B; Possenti, A; Burgay, M; Sabbi, E

    2012-01-01

    We have used deep V and R images acquired at the ESO Very Large Telescope to identify the optical companion to the binary pulsar PSR J0610-2100, one of the black-widow millisecond pulsars recently detected by the Fermi Gamma-ray Telescope in the Galactic plane. We found a faint star (V~26.7) nearly coincident (\\delta r ~0".28) with the pulsar nominal position. This star is visible only in half of the available images, while it disappears in the deepest ones (those acquired under the best seeing conditions), thus indicating that it is variable. Although our observations do not sample the entire orbital period (P=0.28 d) of the pulsar, we found that the optical modulation of the variable star nicely correlates with the pulsar orbital period and describes a well defined peak (R~25.6) at \\Phi=0.75, suggesting a modulation due to the pulsar heating. We tentatively conclude that the companion to PSR J0610-2100 is a heavily ablated very low mass star (~ 0.02Msun) that completely filled its Roche Lobe.

  4. Discovery of a Pulsar Candidate Associated with the TeV Gamma-ray Source HESS J1813-178

    CERN Document Server

    Gotthelf, E V

    2007-01-01

    We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We resolve the X-ray emission from the co-located ASCA source into a compact object surrounded by structured diffuse emission that fills the interior of the radio shell. The morphology of the diffuse emission strongly resembles that of a pulsar wind nebula. The spectrum of the compact source is well-characterized by a power-law with index approx. 1.3, typical of young and energetic rotation-powered pulsars. For a distance of 4.5 kpc, consistent with the X-ray absorption, the 2-10 keV X-ray luminosity of the putative pulsar and nebula is L(PSR) = 3.2E33 erg/s and L(PWN) = 1.4E34 erg/s, respectively. Both the flux ratio of L(PWN)/L(PSR) = 4.3 and the total luminosity of this system imply a pulsar spin-down power greater then 1E37 erg/s, on a par with the top ten most energetic young pulsars in the Galaxy. We associate the putative pulsar with the radio remnant and ...

  5. The Spin-down of PSR J0821-4300 and PSR J1210-5226: Confirmation of Central Compact Objects as Anti-magnetars

    Science.gov (United States)

    Gotthelf, E. V.; Halpern, J. P.; Alford, J.

    2013-03-01

    Using XMM-Newton and Chandra, we measure period derivatives for the second and third known pulsars in the class of central compact objects (CCOs) in supernova remnants, proving that these young neutron stars have exceptionally weak dipole magnetic field components. For the 112 ms PSR J0821-4300 in Puppis A, \\dot{P} = (9.28 +/- 0.36) \\times 10^{-18}. Its proper motion, μ = 61 ± 9 mas yr-1, was also measured using Chandra. This contributes a kinematic term to the period derivative via the Shklovskii effect, which is subtracted from \\dot{P} to derive dipole Bs = 2.9 × 1010 G, a value similar to that of the first measured CCO, PSR J1852+0040 in Kes 79, which has Bs = 3.1 × 1010 G. Antipodal surface hot spots with different temperatures and areas are deduced from the X-ray spectrum and pulse profiles. Paradoxically, such nonuniform surface temperature appears to require strong crustal magnetic fields, probably toroidal or quadrupolar components much stronger than the external dipole. A spectral feature, consisting of either an emission line at ≈0.75 keV or an absorption line at ≈0.46 keV, is modulated in strength with the rotation. It may be due to a cyclotron process in a magnetic field on the surface that is slightly stronger than the dipole deduced from the spin-down. We also timed anew the 424 ms PSR J1210-5226, resolving previous ambiguities about its spin-down rate. Its \\dot{P} is (2.22 ± 0.02) × 10-17, corresponding to Bs = 9.8 × 1010 G. This is also compatible with a cyclotron resonance interpretation of its prominent absorption line at 0.7 keV and its harmonics. These results deepen the mystery of the origin and evolution of CCOs: Why are their numerous descendants not evident?

  6. Two Millisecond Pulsars Discovered by the PALFA Survey and a Shapiro Delay Measurement

    CERN Document Server

    Deneva, J S; Cordes, J M; Lyne, A G; Ransom, S M; Cognard, I; Camilo, F; Nice, D J; Stairs, I H; Allen, B; Bhat, N D R; Bogdanov, S; Brazier, A; Champion, D J; Chatterjee, S; Crawford, F; Desvignes, G; Hessels, J W T; Jenet, F A; Kaspi, V M; Knispel, B; Kramer, M; Lazarus, P; van Leeuwen, J; Lorimer, D R; Lynch, R S; McLaughlin, M A; Scholz, P; Siemens, X; Stappers, B W; Stovall, K; Venkataraman, A

    2012-01-01

    We present two millisecond pulsar discoveries from the PALFA survey of the Galactic plane with the Arecibo telescope. PSR J1955+2527 is an isolated pulsar with a period of 4.87 ms, and PSR J1949+3106 has a period of 13.14 ms and is in a 1.9-day binary system with a massive companion. Their timing solutions, based on 4 years of timing measurements with the Arecibo, Green Bank, Nan\\c{c}ay and Jodrell Bank telescopes, allow precise determination of spin and astrometric parameters, including precise determinations of their proper motions. For PSR J1949+3106, we can clearly detect the Shapiro delay. From this we measure the pulsar mass to be 1.47(+0.43/-0.31) solar masses, the companion mass to be 0.85(+0.14/-0.11) solar masses and the orbital inclination to be i = 79.9(+1.6/-1.9) degrees, where uncertainties correspond to +/- 1-\\sigma\\ confidence levels. With continued timing, we expect to also be able to detect the advance of periastron for the J1949+3106 system. This effect, combined with the Shapiro delay, wil...

  7. Timing of a Young Mildly Recycled Pulsar with a Massive White Dwarf Companion

    CERN Document Server

    Lazarus, P; Knispel, B; Freire, P C C; Deneva, J S; Kaspi, V M; Allen, B; Bogdanov, S; Chatterjee, S; Stairs, I H; Zhu, W W

    2013-01-01

    We report on timing observations of the recently discovered binary pulsar PSR J1952+2630 using the Arecibo Observatory. The mildly recycled 20.7-ms pulsar is in a 9.4-hr orbit with a massive, M_WD > 0.93 M_sun, white dwarf (WD) companion. We present, for the first time, a phase-coherent timing solution, with precise spin, astrometric, and Keplerian orbital parameters. This shows that the characteristic age of PSR J1952+2630 is 77 Myr, younger by one order of magnitude than any other recycled pulsar-massive WD system. We derive an upper limit on the true age of the system of 50 Myr. We investigate the formation of PSR J1952+2630 using detailed modelling of the mass-transfer process from a naked helium star on to the neutron star following a common-envelope phase (Case BB Roche-lobe overflow). From our modelling of the progenitor system, we constrain the accretion efficiency of the neutron star, which suggests a value between 100 and 300% of the Eddington accretion limit. We present numerical models of the chem...

  8. The Evolution of PSR J0737-3039B and a Model for Relativistic Spin Precession

    CERN Document Server

    Perera, Benetge; Kramer, Michael; Stairs, Ingrid; Ferdman, Robert; Freire, Paulo; Possenti, Andrea; Breton, Rene; Manchester, Richard N; Burgay, Marta; Lyne, Andrew; Camilo, Fernando

    2010-01-01

    We present the evolution of the radio emission from the 2.8-s pulsar of the double pulsar system PSR J0737-3039A/B. We provide an update on the Burgay et al. (2005) analysis by describing the changes in the pulse profile and flux density over five years of observations, culminating in the B pulsar's radio disappearance in 2008 March. Over this time, the flux density decreases by 0.177 mJy/yr at the brightest orbital phases and the pulse profile evolves from a single to a double peak, with a separation rate of 2.6 deg/yr. The pulse profile changes are most likely caused by relativistic spin precession, but can not be easily explained with a circular hollow-cone beam as in the model of Clifton & Weisberg (2008). Relativistic spin precession, coupled with an elliptical beam, can model the pulse profile evolution well. This particular beam shape predicts geometrical parameters for the two bright orbital phases which are consistent and similar to those derived by Breton et al. (2008). However, the observed dec...

  9. The Galactic One-Way Shapiro Delay to PSR B1937+21

    CERN Document Server

    Desai, S

    2015-01-01

    The time delay experienced by a light ray as it passes through a changing gravitational potential by a non-zero mass distribution along the line of sight is usually referred to as Shapiro delay. Shapiro delay has been extensively measured in the Solar system and in binary pulsars, enabling stringent tests of general relativity as well as measurement of neutron star masses . However, Shapiro delay is ubiquitous and experienced by all astrophysical messengers on their way from the source to the Earth. We calculate the "one-way" static Shapiro delay for the first discovered millisecond pulsar PSR~B1937+21, by including the contributions from both the dark matter and baryonic matter between this pulsar and the Earth. We find a value of approximately 5 days (of which 4.74 days is from the dark matter and 0.22 days from the baryonic matter). We also calculate the modulation of Shapiro delay from the motion of a single dark matter halo, and also evaluate the cumulative effects of the motion of matter distribution on...

  10. Simultaneous radio and X-ray observations of PSR B0611+22

    CERN Document Server

    Rajwade, Kaustubh; Lorimer, Duncan R; Karastergiou, Aris; Serylak, Maciej; McLaughlin, Maura A; Griessmeier, Jean M

    2016-01-01

    We report results from simultaneous radio and X-ray observations of PSR B0611+22 which is known to exhibit bursting in its single-pulse emission. The pulse phase of the bursts vary with radio frequency. The bursts are correlated in 327/150~MHz datasets while they are anti-correlated, with bursts at one frequency associated with normal emission at the other, in 820/150~MHz datasets. Also, the flux density of this pulsar is lower than expected at 327~MHz assuming a power law. We attribute this unusual behaviour to the pulsar itself rather than absorption by external astrophysical sources. Using this dataset over an extensive frequency range, we show that the bursting phenomenon in this pulsar exhibits temporal variance over a span of few hours. We also show that the bursting is quasi-periodic over the observed band. The anti-correlation in the phase offset of the burst mode at different frequencies suggests that the mechanisms responsible for phase offset and flux enhancement have different dependencies on the ...

  11. The dynamics of Bow-shock Pulsar Wind Nebula: Reconstruction of multi-bubbles

    Science.gov (United States)

    Yoon, Doosoo; Heinz, Sebastian

    2014-08-01

    Bow-shock pulsar wind nebulae (PWNe) exhibit a characteristic cometary shape due to the supersonic motion of the pulsar interacting with the interstellar medium (ISM). One of the spectacular bow-shock is the Guitar Nebula, which is produced by the fast pulsar PSR B2224+65 (vpsr > 1000 km s-1 ), and consists of a bright head, a faint neck, a two larger bubbles. We present that the peculiar mophology arises from variations in the interstellar medium density. We perform 3-D hydrodynamic simulation to understand the evolution of the pulsar as its moves through the density discontinuity. We found that when the pulsar encounters the low-density medium, the pressure balance at the head of the bow shock begins to collapse, producing the second bubble. The expansion rate of the bubble is related to the properties of both the pulsar and the ambient medium. Assuming that the pulsar’s properties, including spin-down energy, are constant, we conclude that the ambient density around the second bubble should be 4.46 times larger than around the first bubble in the Guitar body. We further found that when the pulsar encounters the inclined density dicontinuity, it can produce the asymmetric shape of the bow shock observed in a subset of bow-shock PWNe including J2124-3358.

  12. Limitations in timing precision due to single-pulse shape variability in millisecond pulsars

    CERN Document Server

    Shannon, R M; Dai, S; Bailes, M; Hobbs, G; Manchester, R N; van Straten, W; Raithel, C A; Ravi, V; Toomey, L; Bhat, N D R; Burke-Spolaor, S; Coles, W A; Keith, M J; Kerr, M; Levin, Y; Sarkissian, J M; Wang, J -B; Wen, L; Zhu, X -J

    2014-01-01

    High-sensitivity radio-frequency observations of millisecond pulsars usually show stochastic, broadband, pulse-shape variations intrinsic to the pulsar emission process. These variations induce jitter noise in pulsar timing observations; understanding the properties of this noise is of particular importance for the effort to detect gravitational waves with pulsar timing arrays. We assess the short-term profile and timing stability of 22 millisecond pulsars that are part of the Parkes Pulsar Timing Array sample by examining intra-observation arrival time variability and single-pulse phenomenology. In 7 of the 22 pulsars, in the band centred at approximately 1400MHz, we find that the brightest observations are limited by intrinsic jitter. We find consistent results, either detections or upper limits, for jitter noise in other frequency bands. PSR J1909-3744 shows the lowest levels of jitter noise, which we estimate to contribute $\\sim$10 ns root mean square error to the arrival times for hour-duration observati...

  13. The Scaling of the RMS with Dwell Time in NANOGrav Pulsars

    CERN Document Server

    Handzo, Emma; Lommen, Andrea N; Perrodin, Delphine

    2015-01-01

    Pulsar Timing Arrays (PTAs) are collections of well-timed millisecond pulsars that are being used as detectors of gravitational waves (GWs). Given current sensitivity, projected improvements in PTAs and the predicted strength of the GW signals, the detection of GWs with PTAs could occur within the next decade. One way we can improve a PTA is to reduce the measurement noise present in the pulsar timing residuals. If the pulsars included in the array display uncorrelated noise, the root mean square (RMS) of the timing residuals is predicted to scale as $\\mathrm{T}^{-1/2}$, where T is the dwell time per observation. In this case, the sensitivity of the array can be increased by increasing T. We studied the 17 pulsars in the five year North American Nanohertz Observatory for Gravitational Waves (NANOGrav) data set to determine if the noise in the timing residuals of the pulsars observed was consistent with this property. For comparison, we performed the same analysis on PSR B1937+21, a pulsar that is known to dis...

  14. The Green Bank Northern Celestial Cap Pulsar Survey - I: Survey Description, Data Analysis, and Initial Results

    CERN Document Server

    Stovall, K; Ransom, S M; Archibald, A M; Banaszak, S; Biwer, C M; Boyles, J; Dartez, L P; Day, D; Ford, A J; Flanigan, J; Garcia, A; Hessels, J W T; Hinojosa, J; Jenet, F A; Kaplan, D L; Karako-Argaman, C; Kaspi, V M; Kondratiev, V I; Leake, S; Lorimer, D R; Lunsford, G; Martinez, J G; Mata, A; McLaughlin, M A; Roberts, M S E; Rohr, M D; Siemens, X; Stairs, I H; van Leeuwen, J; Walker, A N; Wells, B L

    2014-01-01

    We describe an ongoing search for pulsars and dispersed pulses of radio emission, such as those from rotating radio transients (RRATs) and fast radio bursts (FRBs), at 350 MHz using the Green Bank Telescope. With the Green Bank Ultimate Pulsar Processing Instrument, we record 100 MHz of bandwidth divided into 4,096 channels every 81.92 $\\mu s$. This survey will cover the entire sky visible to the Green Bank Telescope ($\\delta > -40^\\circ$, or 82% of the sky) and outside of the Galactic Plane will be sensitive enough to detect slow pulsars and low dispersion measure ($<$30 $\\mathrm{pc\\,cm^{-3}}$) millisecond pulsars (MSPs) with a 0.08 duty cycle down to 1.1 mJy. For pulsars with a spectral index of $-$1.6, we will be 2.5 times more sensitive than previous and ongoing surveys over much of our survey region. Here we describe the survey, the data analysis pipeline, initial discovery parameters for 62 pulsars, and timing solutions for 5 new pulsars. PSR J0214$+$5222 is an MSP in a long-period (512 days) orbit a...

  15. Pulsar Ephemerides for Timing LAT Pulsars

    Data.gov (United States)

    National Aeronautics and Space Administration — Timing pulsars with the LAT requires the use of an ephemeris that covers the time period being analyzed. Below are several resources to provide this useful input to...

  16. Pulsars and Gravity

    CERN Document Server

    Manchester, R N

    2015-01-01

    Pulsars are wonderful gravitational probes. Their tiny size and stellar mass give their rotation periods a stablility comparable to that of atomic frequency standards. This is especially true of the rapidly rotating "millisecond pulsars" (MSPs). Many of these rapidly rotating pulsars are in orbit with another star, allowing pulsar timing to probe relativistic perturbations to the orbital motion. Pulsars have provided the most stringent tests of theories of relativistic gravitation, especially in the strong-field regime, and have shown that Einstein's general theory of relativity is an accurate description of the observed motions. Many other gravitational theories are effectively ruled out or at least severely constrained by these results. MSPs can also be used to form a "Pulsar Timing Array" (PTA). PTAs are Galactic-scale interferometers that have the potential to directly detect nanohertz gravitational waves from astrophysical sources. Orbiting super-massive black holes in the cores of distant galaxies are t...

  17. Two Long-Term Intermittent Pulsars Discovered in the PALFA Survey

    Science.gov (United States)

    Lyne, A. G.; Stappers, B. W.; Freire, P. C. C.; Hessels, J. W. T.; Kaspi, V. M.; Allen, B.; Bogdanov, S.; Brazier, A.; Camilo, F.; Cardoso, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J. S.; Ferdman, R. D.; Jenet, F. A.; Knispel, B.; Lazarus, P.; van Leeuwen, J.; Lynch, R.; Madsen, E.; McLaughlin, M. A.; Parent, E.; Patel, C.; Ransom, S. M.; Scholz, P.; Seymour, A.; Siemens, X.; Spitler, L. G.; Stairs, I. H.; Stovall, K.; Swiggum, J.; Wharton, R. S.; Zhu, W. W.

    2017-01-01

    We report the discovery of two long-term intermittent radio pulsars in the ongoing Pulsar Arecibo L-Band Feed Array survey. Following discovery with the Arecibo Telescope, extended observations of these pulsars over several years at Jodrell Bank Observatory have revealed the details of their rotation and radiation properties. PSRs J1910+0517 and J1929+1357 show long-term extreme bimodal intermittency, switching between active (ON) and inactive (OFF) emission states and indicating the presence of a large, hitherto unrecognized underlying population of such objects. For PSR J1929+1357, the initial duty cycle was fON = 0.008, but two years later, this changed quite abruptly to fON = 0.16. This is the first time that a significant evolution in the activity of an intermittent pulsar has been seen, and we show that the spin-down rate of the pulsar is proportional to the activity. The spin-down rate of PSR J1929+1357 is increased by a factor of 1.8 when it is in active mode, similar to the increase seen in the other three known long-term intermittent pulsars. These discoveries increase the number of known pulsars displaying long-term intermittency to five. These five objects display a remarkably narrow range of spin-down power (\\dot{E} ∼ {10}32 {erg} {{{s}}}-1) and accelerating potential above their polar caps. If confirmed by further discoveries, this trend might be important for understanding the physical mechanisms that cause intermittency.

  18. An extended X-ray object ejected from the PSR B1259-63/LS 2883 binary

    CERN Document Server

    Pavlov, George G; Kargaltsev, Oleg; Rangelov, Blagoy; Durant, Martin

    2015-01-01

    We present the analysis of the Chandra X-ray Observatory observations of the eccentric gamma-ray binary PSR B1259-63/LS 2883. The analysis shows that the extended X-ray feature seen in previous observations is still moving away from the binary with an average projected velocity of about 0.07c and shows a hint of acceleration. The spectrum of the feature appears to be hard (photon index of 0.8) with no sign of softening compared to previously measured values. We interpret it as a clump of plasma ejected from the binary through the interaction of the pulsar with the decretion disk of the O-star around periastron passage. We suggest that the clump is moving in the unshocked relativistic pulsar wind (PW), which can accelerate the clump. Its X-ray emission can be interpreted as synchrotron radiation of the PW shocked by the collision with the clump.

  19. An evolutionary model for the gamma-ray system PSR J1311-3430 and its companion

    CERN Document Server

    Benvenuto, O G; Horvath, J E

    2013-01-01

    The most recent member of the millisecond pulsar with very low-mass companions and short orbital periods class, PSR J1311-3430 (Pletsch et al. 2012) is a remarkable object in various senses. Besides being the first discovered in gamma-rays, its measured features include the very low or absent hydrogen content. We show in this Letter that this important piece of information leads to a very restricted range of initial periods for a given donor mass. For that purpose, we calculate in detail the evolution of the binary system self-consistently, including mass transfer and evaporation, finding the features of the new evolutionary path leading to the observed configuration. It is also important to remark that the detailed evolutionary history of the system naturally leads to a high final pulsar mass, as it seems to be demanded by observations.

  20. Multiwavelength analysis of four millisecond pulsars

    CERN Document Server

    Guillemot, Lucas; Johnson, Tyrel J; Venter, Christo; Harding, Alice K

    2015-01-01

    Radio timing observations of millisecond pulsars (MSPs) in support of Fermi LAT observations of the gamma-ray sky enhance the sensitivity of high-energy pulsation searches. With contemporaneous ephemerides we have detected gamma-ray pulsations from PSR B1937+21, the first MSP ever discovered, and B1957+20, the first known black-widow system. The two MSPs share a number of properties: they are energetic and distant compared to other gamma-ray MSPs, and both of them exhibit aligned radio and gamma-ray emission peaks, indicating co-located emission regions in the outer magnetosphere of the pulsars. However, radio observations are also crucial for revealing MSPs in Fermi unassociated sources. In a search for radio pulsations at the position of such unassociated sources, the Nan\\c{c}ay Radio Telescope discovered two MSPs, PSRs J2017+0603 and J2302+4442, increasing the sample of known Galactic disk MSPs. Subsequent radio timing observations led to the detection of gamma-ray pulsations from these two MSPs as well. W...

  1. Prospects for High-Precision Pulsar Timing

    CERN Document Server

    Liu, K; Kramer, M; Stappers, B W; van Straten, W; Cordes, J M

    2011-01-01

    Timing pulses of pulsars has proved to be a most powerful technique useful to a host of research areas in astronomy and physics. Importantly, the precision of this timing is not only affected by radiometer noise, but also by intrinsic pulse shape changes, interstellar medium (ISM) evolution, instrumental distortions, etc. In this paper we review the known causes of pulse shape variations and assess their effect on the precision and accuracy of a single measurement of pulse arrival time with current instrumentation. Throughout this analysis we use the brightest and most precisely timed millisecond pulsar (MSP), PSR J0437-4715, as a case study, and develop a set of diagnostic tools to evaluate profile stability in timing observations. We conclude that most causes of distortion can be either corrected by state-of-the-art techniques or taken into account in the estimation of time-of-arrival (TOA) uncertainties. The advent of a new generation of radio telescopes (e.g. the Square Kilometre Array, SKA), and their in...

  2. THE DOUBLE PULSAR ECLIPSES. I. PHENOMENOLOGY AND MULTI-FREQUENCY ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Breton, R. P. [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada); Kaspi, V. M. [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); McLaughlin, M. A. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Lyutikov, M. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Kramer, M. [Max Planck Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Ransom, S. M. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Ferdman, R. D. [University of Manchester, Jodrell Bank Centre for Astrophysics, Alan Turing Building, Manchester, M13 9PL (United Kingdom); Camilo, F. [Columbia University, New York, NY 10027 (United States); Possenti, A., E-mail: breton@astro.utoronto.ca [INAF-Osservatorio Astronomico di Cagliari, Poggio dei Pini, strada 54, I-09012 Capoterra (Italy)

    2012-03-10

    The double pulsar PSR J0737-3039A/B displays short, 30 s eclipses that arise around conjunction when the radio waves emitted by pulsar A are absorbed as they propagate through the magnetosphere of its companion pulsar B. These eclipses offer a unique opportunity to directly probe the magnetospheric structure and the plasma properties of pulsar B. We have performed a comprehensive analysis of the eclipse phenomenology using multi-frequency radio observations obtained with the Green Bank Telescope. We have characterized the periodic flux modulations previously discovered at 820 MHz by McLaughlin et al. and investigated the radio frequency dependence of the duration and depth of the eclipses. Based on their weak radio frequency evolution, we conclude that the plasma in pulsar B's magnetosphere requires a large multiplicity factor ({approx}10{sup 5}). We also found that, as expected, flux modulations are present at all radio frequencies in which eclipses can be detected. Their complex behavior is consistent with the confinement of the absorbing plasma in the dipolar magnetic field of pulsar B as suggested by Lyutikov and Thompson and such a geometric connection explains that the observed periodicity is harmonically related to pulsar B's spin frequency. We observe that the eclipses require a sharp transition region beyond which the plasma density drops off abruptly. Such a region defines a plasmasphere that would be well inside the magnetospheric boundary of an undisturbed pulsar. It is also two times smaller than the expected standoff radius calculated using the balance of the wind pressure from pulsar A and the nominally estimated magnetic pressure of pulsar B.

  3. Timing the Eccentric Binary Millisecond Pulsar in NGC 1851

    CERN Document Server

    Freire, P C; Gupta, Y; Freire, Paulo C.; Ransom, Scott M.; Gupta, Yashwant

    2007-01-01

    We have used the Green Bank Telescope to observe the millisecond pulsar PSR J0514-4002A on 43 occasions spread over 2 years. This 5-ms pulsar is located in the globular cluster NGC 1851; it belongs to a binary system and has a highly eccentric (e = 0.888) orbit. We have obtained a phase-coherent timing solution for this object, including very precise position, spin and orbital parameters. The pulsar is located 4.6" (about 1.3 core radii) from the center of the cluster, and is likely to lie on its more distant half. The non-detection of eclipses at superior conjunction can be used, given the peculiar geometry of this system, to rule out the possibility of an extended companion. We have measured the rate of advance of periastron for this binary system to be $\\dot{\\omega}$ = 0.01289(4) degrees per year, which if due completely to general relativity, implies a total system mass of 2.453(14) solar masses. Given the known mass function, the pulsar mass has to be 0.96 solar masses, implying that it is a heavy white...

  4. A puzzling millisecond pulsar companion in NGC 6266

    CERN Document Server

    Cocozza, G; Possenti, A; Beccari, G; Lanzoni, B; Ranson, S; Rood, R T; D'Amico, N

    2008-01-01

    We report on the optical identification of the companion to the eclipsing millisecond pulsar PSR J1701$-$3006B in the globular cluster NGC 6266. A relatively bright star with an anomalous red colour and an optical variability ($\\sim$ 0.2 mag) that nicely correlates with the orbital period of the pulsar ($\\sim$ 0.144 days) has been found nearly coincident with the pulsar nominal position. This star is also found to lie within the error box position of an X-ray source detected by Chandra observations, thus supporting the hypothesis that some interaction is occurring between the pulsar wind and the gas streaming off the companion. Although the shape of the optical light curve is suggestive of a tidally deformed star which has nearly completely filled its Roche lobe, the luminosity ($\\sim 1.9 L_\\odot$) and the surface temperature ($\\sim 6000$ K) of the star, deduced from the observed magnitude and colours, would imply a stellar radius significantly larger than the Roche lobe radius. Possible explanations for this...

  5. Unusual Braking Indices in Young X-ray Pulsars

    Science.gov (United States)

    Frederic Archibald, Robert; Kaspi, Victoria M.; Beardmore, Andrew P.; Gehrels, Neil; Kennea, Jamie; Gotthelf, Eric V.; Ferdman, Robert; Guillot, Sebastien; Harrison, Fiona; Keane, Evan; Pivovaroff, Michael; Stern, Daniel; Tendulkar, Shriharsh P.; Tomsick, John

    2016-04-01

    Pulsars spin down over time. By measuring braking indices of pulsars, effectively the change in the spin-down rate over time, we can probe the underlying driving engine of the spin-down. For a magnetic dipole in a vacuum, n is predicted to be 3. To date, all measured braking indices are less than 3, which can be explained, e.g. by particle winds, changes in the magnetic field. In all models of braking indices, n should be nearly constant on year time-scales. Here, I will discuss two recent observation results that challenge this model, interestingly both coming from young X-ray pulsars with no detected radio emission. The first, a long-lived decrease in the braking index of PSR J1846-0258 following a burst of magnetar-like activity, and secondly, the first stationary braking index greater than three. Understanding neutron-star spin evolution is key to constraining these objects' long-term energy output and has relevance to topics ranging from pulsar wind nebulae and supernova remnants to core-collapse supernova rates, physics, and expected outcomes.

  6. Understanding the evolution of close binary systems with radio pulsars

    CERN Document Server

    Benvenuto, O G; Horvath, J E

    2014-01-01

    We calculate the evolution of close binary systems (CBSs) formed by a neutron star (behaving as a radio pulsar) and a normal donor star, evolving either to helium white dwarf (HeWD) or ultra short orbital period systems. We consider X-ray irradiation feedback and evaporation due to radio pulsar irradiation. We show that irradiation feedback leads to cyclic mass transfer episodes, allowing CBSs to be observed in-between as binary radio pulsars under conditions in which standard, non-irradiated models predict the occurrence of a low mass X-ray binary. This behavior accounts for the existence of a family of eclipsing binary systems known as redbacks. We predict that redback companions should almost fill their Roche lobe, as observed in PSR J1723-2837. This state is also possible for systems evolving with larger orbital periods. Therefore, binary radio pulsars with companion star masses usually interpreted as larger than expected to produce HeWDs may also result in such {\\it quasi - Roche Lobe Overflow} states, r...

  7. A millisecond pulsar in a stellar triple system

    CERN Document Server

    Ransom, S M; Archibald, A M; Hessels, J W T; Kaplan, D L; van Kerkwijk, M H; Boyles, J; Deller, A T; Chatterjee, S; Schechtman-Rook, A; Berndsen, A; Lynch, R S; Lorimer, D R; Karako-Argaman, C; Kaspi, V M; Kondratiev, V I; McLaughlin, M A; van Leeuwen, J; Rosen, R; Roberts, M S E; Stovall, K

    2014-01-01

    Gravitationally bound three-body systems have been studied for hundreds of years and are common in our Galaxy. They show complex orbital interactions, which can constrain the compositions, masses, and interior structures of the bodies and test theories of gravity, if sufficiently precise measurements are available. A triple system containing a radio pulsar could provide such measurements, but the only previously known such system, B1620-26 (with a millisecond pulsar, a white dwarf, and a planetary-mass object in an orbit of several decades), shows only weak interactions. Here we report precision timing and multi-wavelength observations of PSR J0337+1715, a millisecond pulsar in a hierarchical triple system with two other stars. Strong gravitational interactions are apparent and provide the masses of the pulsar (1.4378(13) Msun, where Msun is the solar mass and the parentheses contain the uncertainty in the final decimal places) and the two white dwarf companions (0.19751(15) Msun and 0.4101(3) Msun), as well ...

  8. The High Time Resolution Universe Survey - XI. Discovery of five recycled pulsars and the optical detectability of survey white dwarf companions

    CERN Document Server

    Bates, S D; Bailes, M; Barr, E; Bassa, C G; Bhat, N D R; Burgay, M; Burke-Spolaor, S; Champion, D J; Flynn, C M L; Jameson, A; Johnston, S; Keith, M J; Kramer, M; Levin, L; Lyne, A; Milia, S; Ng, C; Petroff, E; Possenti, A; Stappers, B W; van Straten, W; Tiburzi, C

    2014-01-01

    We present the discovery of a further five recycled pulsar systems in the mid-Galactic latitude portion of the High Time Resolution Universe (HTRU) Survey. The pulsars have rotational periods ranging from 2 ms to 66 ms, and four are in binary systems with orbital periods between 10.8 hours and 9.0 days. Three of these binary systems are particularly interesting; PSR J1227-6208 has a pulse period of 34.5 ms and the highest mass function of all pulsars with near-circular orbits. The circular orbit suggests that the companion is not another neutron star, so future timing experiments may reveal one of the heaviest white dwarfs ever found ($>$ 1.3 M$_\\odot$). Timing observations of PSR J1431$-$4715 indicate that it is eclipsed by its companion which has a mass indicating it belongs to the redback class of eclipsing millisecond pulsars. PSR J1653-2054 has a companion with a minimum mass of only $0.08$ M$_\\odot$, placing it among the class of pulsars with low-mass companions. Unlike the majority of such systems, how...

  9. Einstein@Home Finds an Elusive Pulsar

    Science.gov (United States)

    Kohler, Susanna

    2015-08-01

    be at the edge. This adaptive flexibility is what allowed the pulsar's actual location — shown by the solid ellipse, inset — to be found. [Clark et al., 2015] Teasing the Signal From Misinformation: This new search method turned out to be exactly what was needed: the team was able to identify pulsed emission coming from a point located significantly outside of the source's original confidence region. This source, now named PSR J1906+0722, has been determined to be a young, energetic, isolated pulsar, and the team was able to identify its spin parameters and pulse history from the last six years. So why was this mysterious pulsar so hard to find? Its misidentified position, most likely due to a secondary source that had been lumped with the pulsar into a single source, was the biggest factor. Additionally, the pulsar had an enormous glitch one year into Fermi observations of it, making it even more difficult to pin down its pulse profile. The team’s success in spite of these complications indicates the value of their methods for identifying other young, gamma-ray, radio-quiet pulsars that are likely hidden in the Fermi-LAT catalog. Citation: C. J. Clark et al. 2015 ApJ, 809, L2. doi:10.1088/2041-8205/809/1/L2

  10. UNDERSTANDING THE EVOLUTION OF CLOSE BINARY SYSTEMS WITH RADIO PULSARS

    Energy Technology Data Exchange (ETDEWEB)

    Benvenuto, O. G. [Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, 1900 La Plata, Buenos Aires (Argentina); De Vito, M. A. [Instituto de Astrofísica de La Plata (IALP), CCT-CONICET-UNLP. Paseo del Bosque S/N (B1900FWA), La Plata (Argentina); Horvath, J. E., E-mail: obenvenu@fcaglp.unlp.edu.ar, E-mail: adevito@fcaglp.unlp.edu.ar, E-mail: foton@astro.iag.usp.br [Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo R. do Matão 1226 (05508-090), Cidade Universitária, São Paulo SP (Brazil)

    2014-05-01

    We calculate the evolution of close binary systems (CBSs) formed by a neutron star (behaving as a radio pulsar) and a normal donor star, which evolve either to a helium white dwarf (HeWD) or to ultra-short orbital period systems. We consider X-ray irradiation feedback and evaporation due to radio pulsar irradiation. We show that irradiation feedback leads to cyclic mass transfer episodes, allowing CBSs to be observed in between episodes as binary radio pulsars under conditions in which standard, non-irradiated models predict the occurrence of a low-mass X-ray binary. This behavior accounts for the existence of a family of eclipsing binary systems known as redbacks. We predict that redback companions should almost fill their Roche lobe, as observed in PSR J1723-2837. This state is also possible for systems evolving with larger orbital periods. Therefore, binary radio pulsars with companion star masses usually interpreted as larger than expected to produce HeWDs may also result in such quasi-Roche lobe overflow states, rather than hosting a carbon-oxygen WD. We found that CBSs with initial orbital periods of P{sub i} < 1 day evolve into redbacks. Some of them produce low-mass HeWDs, and a subgroup with shorter P{sub i} becomes black widows (BWs). Thus, BWs descend from redbacks, although not all redbacks evolve into BWs. There is mounting observational evidence favoring BW pulsars to be very massive (≳ 2 M {sub ☉}). As they should be redback descendants, redback pulsars should also be very massive, since most of the mass is transferred before this stage.

  11. Pulsar searches of Fermi unassociated sources with the Effelsberg telescope

    CERN Document Server

    Barr, E D; Champion, D J; Kramer, M; Eatough, R P; Lee, K J; Verbiest, J P W; Bassa, C G; Camilo, F; \\cCelik, Ö; Cognard, I; Ferrara, E C; Freire, P C C; Janssen, G H; Johnston, S; Keith, M; Lyne, A G; Michelson, P F; Parkinson, P M Saz; Ransom, S M; Ray, P S; Stappers, B W; Wood, K S; 10.1093/mnras/sts449

    2013-01-01

    Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated gamma-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published in the 1FGL catalogue (Abdo et al., 2010). This survey resulted in the discovery of millisecond pulsar J1745+1017, which resides in a short-period binary system with a low-mass companion, Mmin ~ 0.0137 Msun, indicative of `Black Widow' type systems. A two-year timing campaign has produced a refined radio ephemeris, accurate enough to allow for phase-folding of the LAT photons, resulting in the detection of a dual-peaked gamma-ray light-curve, proving that PSR J1745+1017 is the source responsible for the gamma-ray emission seen in 1FGL J1745.5 + 1018 (2FGL J1745.6+1015; Nolan et al., 2012). We find the gamma-ray spectrum of PSR J1745+1017 to be well modelled by an exponentially-cut-off power law with cut-off energy 3.2 GeV and photon index 1.6. The observed sources are known ...

  12. The impact of a stochastic gravitational-wave background on pulsar timing parameters

    CERN Document Server

    Ellis, J; Verbiest, J P W

    2011-01-01

    Gravitational waves are predicted by Einstein's theory of general relativity as well as other theories of gravity. The rotational stability of the fastest pulsars means that timing of an array of these objects can be used to detect and investigate gravitational waves. Simultaneously, however, pulsar timing is used to estimate spin period, period derivative, astrometric, and binary parameters. Here we calculate the effects that a stochastic background of gravitational waves has on pulsar timing parameters through the use of simulations and data from the millisecond pulsars PSR J0437--4715 and PSR J1713+0747. We show that the reported timing uncertainties become underestimated with increasing background amplitude by up to a factor of $\\sim10$ for a stochastic gravitational-wave background amplitude of $A=5\\times 10^{-15}$, where $A$ is the amplitude of the characteristic strain spectrum at one-year gravitational wave periods. We find evidence for prominent low-frequency spectral leakage in simulated data sets i...

  13. Formation of Double Neutron Stars, Millisecond Pulsars and Double Black Holes

    Science.gov (United States)

    van den Heuvel, Edward P. J.

    2017-09-01

    The 1982 model for the formation of Hulse-Taylor binary radio pulsar PSR B1913+16 is described, which since has become the `standard model' for the formation of the double neutron stars, confirmed by the 2003 discovery of the double pulsar system PSR J0737-3039AB. A brief overview is given of the present status of our knowledge of the double neutron stars, of which 15 systems are presently known. The binary-recycling model for the formation of millisecond pulsars is described, as put forward independently by Alpar et al. (1982), Radhakrishnan & Srinivasan (1982) and Fabian et al. (1983). This now is the `standard model' for the formation of these objects, confirmed by the discovery in 1998 of the accreting millisecond X-ray pulsars. It is noticed that the formation process of close double black holes has analogies to that of close double neutron stars, extended to binaries with larger initial component masses, although there are also considerable differences in the physics of the binary evolution at these larger masses.

  14. Formation of Double Neutron Stars, Millisecond Pulsars and Double Black Holes

    Indian Academy of Sciences (India)

    Edward P. J. Van Den Heuvel

    2017-09-01

    The 1982 model for the formation of Hulse–Taylor binary radio pulsar PSR B1913+16 is described, which since has become the ‘standard model’ for the formation of the double neutron stars, confirmed by the 2003 discovery of the double pulsar system PSR J0737-3039AB. A brief overview is given of the present status of our knowledge of the double neutron stars, of which 15 systems are presently known. The binary-recycling model for the formation of millisecond pulsars is described, as put forward independently by Alpar et al. (1982), Radhakrishnan & Srinivasan (1982) and Fabian et al. (1983). This now is the ‘standard model’ for the formation of these objects, confirmed by the discovery in 1998 of the accreting millisecond X-ray pulsars. It is noticed that the formation process of close double black holes has analogies to that of close double neutron stars, extended to binaries with larger initial component masses, although there are also considerable differences in the physics of the binary evolution at these larger masses.

  15. Parkes radio searches of Fermi gamma-ray sources and millisecond pulsar discoveries

    CERN Document Server

    Camilo, F; Ray, P S; Ransom, S M; Sarkissian, J; Cromartie, H T; Johnston, S; Reynolds, J E; Wolff, M T; Freire, P C C; Bhattacharyya, B; Ferrara, E C; Keith, M; Michelson, P F; Parkinson, P M Saz; Wood, K S

    2015-01-01

    In a search with the Parkes radio telescope of 56 unidentified Fermi-LAT gamma-ray sources, we have detected 11 millisecond pulsars (MSPs), 10 of them discoveries, of which five were reported in Kerr et al. (2012). We did not detect radio pulsations from another six pulsars now known in these sources. We describe the completed survey, which included multiple observations of many targets done to minimize the impact of interstellar scintillation, acceleration effects in binary systems, and eclipses. We consider that 23 of the 39 remaining sources may still be viable pulsar candidates. We present timing solutions and polarimetry for five of the MSPs, and gamma-ray pulsations for PSR J1903-7051 (pulsations for five others were reported in the second Fermi-LAT catalog of gamma-ray pulsars). Two of the new MSPs are isolated and five are in >1 d circular orbits with 0.2-0.3 Msun presumed white dwarf companions. PSR J0955-6150, in a 24 d orbit with a ~0.25 Msun companion but eccentricity of 0.11, belongs to a recentl...

  16. Alternancia entre el estado de emisión de Rayos-X y Pulsar en Sistemas Binarios Interactuantes

    Science.gov (United States)

    De Vito, M. A.; Benvenuto, O. G.; Horvath, J. E.

    2015-08-01

    Redbacks belong to the family of binary systems in which one of the components is a pulsar. Recent observations show redbacks that have switched their state from pulsar - low mass companion (where the accretion of material over the pulsar has ceased) to low mass X-ray binary system (where emission is produced by the mass accretion on the pulsar), or inversely. The irradiation effect included in our models leads to cyclic mass transfer episodes, which allow close binary systems to switch between one state to other. We apply our results to the case of PSR J1723-2837, and discuss the need to include new ingredients in our code of binary evolution to describe the observed state transitions.

  17. A broadband radio study of the average profile and giant pulses from PSR B1821-24A

    CERN Document Server

    Bilous, A V; Demorest, P; Ransom, S M

    2014-01-01

    We present the results of wide-band (720-2400 MHz) study of PSR B1821-24A (J1824-2452A, M28A), an energetic millisecond pulsar visible in radio, X-rays and gamma-rays. In radio, the pulsar has a complex average profile which spans >85% of the spin period and exhibits strong evolution with observing frequency. For the first time we measure phase-resolved polarization properties and spectral indices of radio emission throughout almost all of the on-pulse window. We combine this knowledge with the high-energy information to compare M28A to other known gamma-ray millisecond pulsars and to speculate that M28A's radio emission originates in multiple regions within its magnetosphere (i.e. both in the slot or outer gaps near the light cylinder and at lower altitudes above the polar cap). M28A is one of the handful of pulsars which are known to emit Giant Pulses (GPs) -- short, bright radio pulses of unknown nature. We report a drop in the linear polarization of the average profile in both windows of GP generation and...

  18. 2FGL J1653.6-0159: A New Low in Evaporating Pulsar Binary Periods

    CERN Document Server

    Romani, Roger W; Cenko, S Bradley

    2014-01-01

    We have identified an optical binary with orbital period P_b=4488s as the probable counterpart of the Fermi source 2FGL J1653.6-0159. Although pulsations have not yet been detected, the source properties are consistent with an evaporating millisecond pulsar binary; this P_b=75min is the record low for a spin-powered system. The heated side of the companion shows coherent radial velocity variations, with amplitude K=666.9+/-7.5 km/s for a large mass function of f(M)=1.60+/-0.05 M_sun. This heating suggests a pulsar luminosity ~3x10^34 erg/s. The colors and spectra show additional hard emission dominating at binary minimum. This system is similar to PSR J1311-3430, with a low mass H-depleted companion, a dense shrouding wind and, likely, a large pulsar mass.

  19. Transformation of a star into a planet in a millisecond pulsar binary.

    Science.gov (United States)

    Bailes, M; Bates, S D; Bhalerao, V; Bhat, N D R; Burgay, M; Burke-Spolaor, S; D'Amico, N; Johnston, S; Keith, M J; Kramer, M; Kulkarni, S R; Levin, L; Lyne, A G; Milia, S; Possenti, A; Spitler, L; Stappers, B; van Straten, W

    2011-09-23

    Millisecond pulsars are thought to be neutron stars that have been spun-up by accretion of matter from a binary companion. Although most are in binary systems, some 30% are solitary, and their origin is therefore mysterious. PSR J1719-1438, a 5.7-millisecond pulsar, was detected in a recent survey with the Parkes 64-meter radio telescope. We show that this pulsar is in a binary system with an orbital period of 2.2 hours. The mass of its companion is near that of Jupiter, but its minimum density of 23 grams per cubic centimeter suggests that it may be an ultralow-mass carbon white dwarf. This system may thus have once been an ultracompact low-mass x-ray binary, where the companion narrowly avoided complete destruction.

  20. The NANOGrav Nine-year Data Set: Astrometric Measurements of 37 Millisecond Pulsars

    CERN Document Server

    Matthews, Allison M; Fonseca, Emmanuel; Arzoumanian, Zaven; Crowter, Kathryn; Demorest, Paul B; Dolch, Timothy; Ellis, Justin A; Ferdman, Robert D; Gonzalez, Marjorie E; Jones, Glenn; Jones, Megan L; Lam, Michael T; Levin, Lina; McLaughlin, Maura A; Pennucci, Timothy T; Ransom, Scott M; Stairs, Ingrid H; Stovall, Kevin; Swiggum, Joseph K; Zhu, Weiwei

    2015-01-01

    Using the nine-year radio-pulsar timing data set from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), collected at Arecibo Observatory and the Green Bank Telescope, we have measured the positions, proper motions, and parallaxes for 37 millisecond pulsars. We report eleven significant parallax measurements and distance measurements, and nineteen lower limits on distance. We compare these measurements to distances predicted by the NE2001 interstellar electron density model and find them to be in general agreement. We use measured orbital-decay rates and spin-down rates to confirm two of the parallax distances and to place distance upper limits on other sources; these distance limits agree with the parallax distances with one exception, PSR J1024-0719, which we discuss at length. Using our measurements in combination with other published measurements, we calculate the velocity dispersion of the millisecond pulsar population in Galactocentric coordinates. We find the radial, azimuthal...

  1. From Spin Noise to Systematics: Stochastic Processes in the First International Pulsar Timing Array Data Release

    CERN Document Server

    Lentati, L; Coles, W A; Verbiest, J P W; van Haasteren, R; Ellis, J A; Caballero, R N; Manchester, R N; Arzoumanian, Z; Babak, S; Bassa, C G; Bhat, N D R; Brem, P; Burgay, M; Burke-Spolaor, S; Champion, D; Chatterjee, S; Cognard, I; Cordes, J M; Dai, S; Demorest, P; Desvignes, G; Dolch, T; Ferdman, R D; Fonseca, E; Gair, J R; Gonzalez, M E; Graikou, E; Guillemot, L; Hessels, J W T; Hobbs, G; Janssen, G H; Jones, G; Karuppusamy, R; Keith, M; Kerr, M; Kramer, M; Lam, M T; Lasky, P D; Lassus, A; Lazarus, P; Lazio, T J W; Lee, K J; Levin, L; Liu, K; Lynch, R S; Madison, D R; McKee, J; McLaughlin, M; McWilliams, S T; Mingarelli, C M F; Nice, D J; Osłowski, S; Pennucci, T T; Perera, B B P; Perrodin, D; Petiteau, A; Possenti, A; Ransom, S M; Reardon, D; Rosado, P A; Sanidas, S A; Sesana, A; Shaifullah, G; Siemens, X; Smits, R; Stairs, I; Stappers, B; Stinebring, D R; Stovall, K; Swiggum, J; Taylor, S R; Theureau, G; Tiburzi, C; Toomey, L; Vallisneri, M; van Straten, W; Vecchio, A; Wang, J -B; Wang, Y; You, X P; Zhu, W W; Zhu, X -J

    2016-01-01

    We analyse the stochastic properties of the 49 pulsars that comprise the first International Pulsar Timing Array (IPTA) data release. We use Bayesian methodology, performing model selection to determine the optimal description of the stochastic signals present in each pulsar. In addition to spin-noise and dispersion-measure (DM) variations, these models can include timing noise unique to a single observing system, or frequency band. We show the improved radio-frequency coverage and presence of overlapping data from different observing systems in the IPTA data set enables us to separate both system and band-dependent effects with much greater efficacy than in the individual PTA data sets. For example, we show that PSR J1643$-$1224 has, in addition to DM variations, significant band-dependent noise that is coherent between PTAs which we interpret as coming from time-variable scattering or refraction in the ionised interstellar medium. Failing to model these different contributions appropriately can dramatically...

  2. Magnetar-like emission from the young pulsar in Kes 75.

    Science.gov (United States)

    Gavriil, F P; Gonzalez, M E; Gotthelf, E V; Kaspi, V M; Livingstone, M A; Woods, P M

    2008-03-28

    We report the detection of magnetar-like x-ray bursts from the young pulsar PSR J1846-0258, at the center of the supernova remnant Kes 75. This pulsar, long thought to be exclusively rotation-powered, has an inferred surface dipolar magnetic field of 4.9 x 10(13) gauss, which is higher than those of the vast majority of rotation-powered pulsars, but lower than those of the approximately 12 previously identified magnetars. The bursts were accompanied by a sudden flux increase and an unprecedented change in timing behavior. These phenomena lower the magnetic and rotational thresholds associated with magnetar-like behavior and suggest that in neutron stars there exists a continuum of magnetic activity that increases with inferred magnetic field strength.

  3. Magnetar-Like Emission from the Young Pulsar in Kes 75

    Science.gov (United States)

    Gavriil, F. P.; Gonzalez, M. E.; Gotthelf, E. V.; Kaspi, V. M.; Livingstone, M. A.; Woods, P. M.

    2008-01-01

    We report the detection of magnetar-like x-ray bursts from the young pulsar PSR J1846-0258, at the center of the supernova remnant Kes 75. This pulsar, long thought to be exclusively rotation-powered, has an inferred surface dipolar magnetic field of 4.9deg 10(exp 13) gauss, which is higher than those of the vast majority of rotation-powered pulsars, but lower than those of the approximately 12 previously identified magnetars. The bursts were accompanied by a sudden flux increase and an unprecedented change in timing behavior. These phenomena lower the magnetic and rotational thresholds associated with magnetar-like behavior and suggest that in neutron stars there exists a continuum of magnetic activity that increases with inferred magnetic field strength.

  4. A Millisecond Pulsar Discovery in a Survey of Unidentified Fermi γ-Ray Sources with LOFAR

    Science.gov (United States)

    Pleunis, Z.; Bassa, C. G.; Hessels, J. W. T.; Kondratiev, V. I.; Camilo, F.; Cognard, I.; Grießmeier, J.-M.; Stappers, B. W.; van Amesfoort, A. S.; Sanidas, S.

    2017-09-01

    Using LOFAR, we have performed a very-low-frequency (115‑155 MHz) radio survey for millisecond pulsars (MSPs). The survey targeted 52 unidentified Fermi γ-ray sources. Employing a combination of coherent and incoherent dedispersion, we have mitigated the dispersive effects of the interstellar medium while maintaining sensitivity to fast-spinning pulsars. Toward 3FGL J1553.1+5437 we have found PSR J1552+5437, the first MSP to be discovered (through its pulsations) at a radio frequency surveys using higher observing frequencies. Detecting such steep spectrum sources is important for mapping the population of MSPs down to the shortest spin periods, understanding their emission in comparison to slow pulsars, and quantifying the prospects for future surveys with low-frequency radio telescopes like SKA-Low and its precursors.

  5. Discovery of Giant Pulses from the Pulsar B1237+25(J1239+2453)

    Science.gov (United States)

    Kazantsev, A. N.; Potapov, V. A.

    2015-01-01

    To search for Giant Pulses (GPs) from pulsars, we have carried out during 2011--2013 a survey of about 20 second-period radio pulsars of the Northern Hemisphere. The observations were carried out at a frequency of 111-MHz using the Large Phased Array (LPA LPI) scanning radio telescope in Pushchino. We have detected regular generation of strong individuals pulses from the pulsar PSR B1237+25 (J1239+2453). The peak flux density of the pulses was up to 70 times as strong as an average profile. The flux density of these pulses has a bimodal power-law distribution function, which is typical of GPs when usual pulses are log-normally distributed. The strongest detected GP had a flux density of about 900 Jy.

  6. A New, Low Braking Index For the LMC Pulsar B0540-69

    CERN Document Server

    Marshall, F E; Harding, A K; Martin, P; Smith, D A

    2016-01-01

    We report the results of a 16-month monitoring campaign using the Swift satellite of PSR B0540-69, a young pulsar in the Large Magellanic Cloud. Phase connection was maintained throughout the campaign so that a reliable ephemeris could be determined, and the length of the campaign is adequate to accurately determine the spin frequency and its first and second derivatives. The braking index is 0.031 +/- 0.013 (90% confidence), a value much lower than previously reported for B0540-69 and almost all other young pulsars. We use data from the extensive monitoring campaign with RXTE to show that timing noise is unlikely to significantly affect the measurement. This is the first measurement of the braking index in the pulsar's recently discovered high spin-down state. We discuss possible mechanisms for producing the low braking index.

  7. SAS-2 high-energy gamma-ray observations of the Vela pulsar

    Science.gov (United States)

    Thompson, D. J.; Fichtel, C. E.; Kniffen, D. A.; Ogelman, H. B.

    1975-01-01

    The Second Small Astronomy Satellite (SAS-2) high-energy (in excess of 35 MeV) gamma-ray telescope has detected pulsed gamma-ray emission at the radio period from PSR 0833-45, the Vela pulsar, as well as an unpulsed flux from the Vela region. The pulsed emission consists of two peaks following the single radio peak by about 13 ms and 48 ms. The luminosity of the pulsed emission above 100 MeV from Vela is about 0.1 that of the pulsar NP 0532 in the Crab nebula, whereas the pulsed emission from Vela at optical wavelengths is less than 0.0002 that from the Crab. The relatively high intensity of the pulsed gamma-ray emission, and the double peak structure, compared with the single pulse in the radio emission, suggest that the high-energy gamma-ray pulsar emission may be produced under different conditions from those at lower energies.

  8. The Identification of the Optical Companion to the Binary Millisecond Pulsar J0610-2100 in the Galactic Field

    Science.gov (United States)

    Pallanca, C.; Mignani, R. P.; Dalessandro, E.; Ferraro, F. R.; Lanzoni, B.; Possenti, A.; Burgay, M.; Sabbi, E.

    2012-08-01

    We have used deep V and R images acquired at the ESO Very Large Telescope to identify the optical companion to the binary PSR J0610-2100, one of the black-widow millisecond pulsars recently detected by the Fermi Gamma-ray Space Telescope in the Galactic plane. We found a faint star (V ~ 26.7) nearly coincident (δr ~ 0farcs28) with the pulsar nominal position. This star is visible only in half of the available images, while it disappears in the deepest ones (those acquired under the best-seeing conditions), thus indicating that it is variable. Although our observations do not sample the entire orbital period (P = 0.28 days) of the pulsar, we found that the optical modulation of the variable star nicely correlates with the pulsar orbital period and describes a well-defined peak (R ~ 25.6) at Φ = 0.75, suggesting a modulation due to the pulsar heating. We tentatively conclude that the companion to PSR J0610-2100 is a heavily ablated very low mass star (≈0.02 M ⊙) that completely filled its Roche lobe.

  9. Two Pulsar Wind Nebulae: Chandra/XMM-Newton Imaging of GeV J1417-6100

    CERN Document Server

    Ng, C Y; Romani, R W; Roberts, Mallory S.E.; Romani, Roger W.

    2005-01-01

    We report on Chandra ACIS and XMM-Newton MOS/PN imaging observations of two pulsar wind nebulae (K3/PSR J1420-6048 and G313.3+0.1=`the rabbit') associated with the Galactic unidentified gamma-ray source GeV J1417-6100. With the excellent ACIS imaging, the very energetic pulsar PSR J1420-6048 is separated from its surrounding nebula. This nebula has surprisingly little compact structure, although a faint arc is seen near the pulsar. Similarly, two point sources are resolved in the rabbit nebula. The large XMM-Newton collecting area provides useful spectral constraints on the rabbit and the associated point sources. Based on spectra and X-ray morphology, we identify one point source as a plausible pulsar counterpart. Large backgrounds and low source counts limited pulse search sensitivities, but we report pulse upper limits and a candidate 108ms period for the rabbit pulsar based on the XMM-Newton data and an ACIS CC observation. Comparison of the X-ray images with high resolution ATCA radio maps shows that the...

  10. The NuSTAR view of the non-thermal emission from PSR J0437-4715

    CERN Document Server

    Guillot, Sebastien; Archibald, Robert F; Bachetti, Matteo; Flynn, Chris; Jankowski, Fabian; Bailes, Matthew; Boggs, Steven; Christensen, Finn E; Craig, William W; Hailey, Charles A; Harrison, Fiona A; Stern, Daniel; Zhang, Willam W

    2015-01-01

    We present a hard X-ray NuSTAR observation of PSR J0437-4715, the nearest millisecond pulsar. The known pulsations at the apparent pulse period ~5.76 ms are detected at energies up to 20 keV. We measure a photon index $\\Gamma= 1.65\\pm0.24$ (90% confidence) for the power law fit to the non-thermal emission. It had been shown that spectral models with two or three thermal components fit the XMM-Newton spectrum of PSR J0437-4715, depending on the slope of the power-law component, and the amount of absorption of soft X-rays. The new constraint on the high-energy emission provided by NuSTAR removes ambiguities regarding the thermal components of the emission below 3 keV. We performed a simultaneous spectral analysis of the XMM-Newton and NuSTAR data to confirm that three thermal components and a power law are required to fit the 0.3-20 keV emission of PSR J0437-4715. Adding a ROSAT-PSPC spectrum further confirmed this result and allowed us to better constrain the temperatures of the three thermal components. A pha...

  11. Multi-Zone Modeling of the Pulsar Win Nebula HESS J1825-137

    Energy Technology Data Exchange (ETDEWEB)

    Van Etten, Adam; Romani, Roger W.; /Stanford U., Phys. Dept.

    2011-11-08

    The pulsar wind nebula associated with PSR J1826-1334, HESS J1825-137, is a bright very high energy source with an angular extent of {approx} 1{sup o} and spatially-resolved spectroscopic TeV measurements. The gamma-ray spectral index is observed to soften with increasing distance from the pulsar, likely the result of cooling losses as electrons traverse the nebula. We describe analysis of X-ray data of the extended nebula, as well as 3-D time-dependent spectral energy distribution modeling, with emphasis on the spatial variations within HESS J1825-137. The multi-wavelength data places significant constraints on electron injection, transport, and cooling within the nebula. The large size and high nebular energy budget imply a relatively rapid initial pulsar spin period of 13 {+-} 7 ms and an age of 40 {+-} 9 kyr. The relative fluxes of each VHE zone can be explained by advective particle transport with a radially decreasing velocity profile with v(r) {proportional_to} r{sup -0.5}. The evolution of the cooling break requires an evolving magnetic field which also decreases radially from the pulsar, B(r, t) {proportional_to} r{sup -0.7} E(t){sup 1/2}. Detection of 10 TeV flux {approx} 80 pc from the pulsar requires rapid diffusion of high energy particles with {tau}{sub esc} {approx} 90 (R/10 pc){sup 2}(E{sub e}/100TeV){sup -1} year, contrary to the common assumption of toroidal magnetic fields with strong magnetic confinement. The model predicts a rather uniform Fermi LAT surface brightness out to {approx} 1{sup o} from the pulsar, in good agreement with the recently discovered LAT source centered 0.5{sup o} southwest of PSR J1826-1334 with extension 0.6 {+-} 0.1{sup o}.

  12. The Braking Index of Radio-quiet Gamma-ray Pulsar

    CERN Document Server

    Clark, C J; Wu, J; Guillemot, L; Camilo, F; Johnson, T J; Kerr, M; Allen, B; Aulbert, C; Beer, C; Bock, O; Cuéllar, A; Eggenstein, H B; Fehrmann, H; Kramer, M; Machenschalk, B; Nieder, L

    2016-01-01

    We report the discovery and timing measurements of PSR J1208-6238, a young and highly magnetized gamma-ray pulsar, with a spin period of 440 ms. The pulsar was discovered in gamma-ray photon data from the Fermi Large Area Telescope (LAT) during a blind-search survey of unidentified LAT sources, running on the distributed volunteer computing system Einstein@Home. No radio pulsations were detected in dedicated follow-up searches with the Parkes radio telescope, with a flux density upper limit at 1369 MHz of 30 $\\mu$Jy. By timing this pulsar's gamma-ray pulsations, we measure its braking index over five years of LAT observations to be $n = 2.598 \\pm 0.001 \\pm 0.1$, where the first uncertainty is statistical and the second estimates the bias due to timing noise. Assuming its braking index has been similar since birth, the pulsar has an estimated age of around 2,700 yr, making it the youngest pulsar to be found in a blind search of gamma-ray data and the youngest known radio-quiet gamma-ray pulsar. Despite its you...

  13. Formation of binary millisecond pulsars with relatively high surface dipole magnetic fields

    CERN Document Server

    Sutantyo, W

    2000-01-01

    We have carried out numerical evolutionary calculations of binary systems to investigate the formation of binary millisecond pulsars (pulsars with white dwarf companions). We apply the ``standard scenario'' in which the binary pulsars are formed from low-mass and intermediate-mass X-ray binaries as well the alternative scenario in which the neutron stars are formed by accretion-induced collapse (AIC) of white dwarfs. The mass transfer processes are carefully followed by taking into account a number of binary interactions. Assuming that the magnetic fields of the neutron stars decay due to the accretion, we calculate the pulsar surface dipole magnetic field strength at the end of the mass transfer as a function of the final orbital period. We find that while the observed data of the majority of pulsars are compatible with the derived relations, we fail to produce binary pulsars with relatively high magnetic fields and short orbital periods (such as PSR B0655+64). We conclude that those systems are most likely ...

  14. Einstein@Home discovery of four young gamma-ray pulsars in Fermi LAT data

    CERN Document Server

    Pletsch, H J; Allen, B; Anderson, D; Aulbert, C; Bock, O; Champion, D J; Eggenstein, H B; Fehrmann, H; Hammer, D; Karuppusamy, R; Keith, M; Kramer, M; Machenschalk, B; Ng, C; Papa, M A; Ray, P S; Siemens, X

    2013-01-01

    We report the discovery of four gamma-ray pulsars, detected in computing-intensive blind searches of data from the Fermi Large Area Telescope (LAT). The pulsars were found using a novel search approach, combining volunteer distributed computing via Einstein@Home and methods originally developed in gravitational-wave astronomy. The pulsars PSRs J0554+3107, J1422-6138, J1522-5735, and J1932+1916 are young and energetic, with characteristic ages between 35 and 56 kyr and spin-down powers in the range $6\\times10^{34}$ - $10^{36}$ erg s$^{-1}$. They are located in the Galactic plane and have rotation rates of less than 10 Hz, among which the 2.1 Hz spin frequency of PSR J0554+3107 is the slowest of any known gamma-ray pulsar. For two of the new pulsars, we find supernova remnants coincident on the sky and discuss the plausibility of such associations. Deep radio follow-up observations found no pulsations, suggesting that all four pulsars are radio-quiet as viewed from Earth. These discoveries, the first gamma-ray ...

  15. Pulsar searches of Fermi unassociated sources with the Effelsberg telescope

    Science.gov (United States)

    Barr, E. D.; Guillemot, L.; Champion, D. J.; Kramer, M.; Eatough, R. P.; Lee, K. J.; Verbiest, J. P. W.; Bassa, C. G.; Camilo, F.; Çelik, Ö.; Cognard, I.; Ferrara, E. C.; Freire, P. C. C.; Janssen, G. H.; Johnston, S.; Keith, M.; Lyne, A. G.; Michelson, P. F.; Parkinson, P. M. Saz; Ransom, S. M.; Ray, P. S.; Stappers, B. W.; Wood, K. S.

    2013-02-01

    Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated γ-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published in the 1FGL catalogue (Abdo et al. 2010a). This survey resulted in the discovery of millisecond pulsar J1745+1017, which resides in a short-period binary system with a low-mass companion, M_{c,{min}} ˜ 0.0137 M_{⊙}, indicative of `black widow' type systems. A 2-yr timing campaign has produced a refined radio ephemeris, accurate enough to allow for phase-folding of the LAT photons, resulting in the detection of a dual-peaked γ-ray light curve, proving that PSR J1745+1017 is the source responsible for the γ-ray emission seen in 1FGL J1745.5+1018 (2FGL J1745.6+1015; Nolan et al. 2012). We find the γ-ray spectrum of PSR J1745+1017 to be well modelled by an exponentially cut-off power law with cut-off energy 3.2 GeV and photon index 1.6. The observed sources are known to contain a further 10 newly discovered pulsars which were undetected in this survey. Our radio observations of these sources are discussed and in all cases limiting flux densities are calculated. The reasons behind the seemingly low yield of discoveries are also discussed.

  16. Searches for Radio Pulsars & Fast Transients and Multiwavelength Studies of Single-pulse Emission

    Science.gov (United States)

    Mickaliger, Mitchell B.

    Pulsars are excellent tools for studying a wide array of astrophysical phenomena (e.g. gravitational waves, the interstellar medium, general relativity), yet they are still not fully understood. What are their emission processes and how do they change at different energies? How is giant pulse emission different from regular emission? How are different classes of pulsars (RRATs, magnetars, nulling pulsars, etc.) related? Answering these questions will not only help us to understand pulsars in general, but will also help improve techniques for pulsar searches and timing, gravitational wave searches, and single-pulse searches. The work we present here aims to answer these questions through studies of giant pulse emission, the discovery of new pulsars, and single-pulse studies of a large population of pulsars and RRATs. We took advantage of open telescope time on the 43-m telescope in Green Bank, WV to conduct a long-term study of giant pulses from the Crab pulsar at 1.2 GHz and 330 MHz. Over a timespan of 15 months, we collected a total of 95000 giant pulses which we correlated with both gamma-ray photons from the Fermi satellite and giant pulses collected at 8.9 GHz. Statistics of these pulses show that their amplitudes follow power-law distributions, with indices in the range of 2.1 to 3.1. The correlation with giant pulses at 8.9 GHz showed that the emission processes at 1.2 GHz and 8.9 GHz are related, despite significant profile differences. The correlation with Fermi gamma-ray photons was to test if increased pair production in the magnetosphere was the cause of giant pulses. Our findings suggest that, while it may play a role, increased pair production is not the dominant cause of giant pulses. As part of a single-pulse study, we reprocessed the archival Parkes Multibeam Pulsar Survey, discovering six previously unknown pulsars. PSR J0922-52 has a period of 9.68 ms and a DM of 122.4 pc cm-3. PSR J1147-66 has a period of 3.72 ms and a DM of 133.8 pc cm-3. PSR J

  17. Analysis and Comparisons of Four Kinds of Ensemble Pulsar Time Algorithm%四种综合脉冲星时算法比较

    Institute of Scientific and Technical Information of China (English)

    仲崇霞; 杨廷高

    2009-01-01

    Pulsars, rapidly rotating neutron stars, have extremely stable rotating periods. The pulsar time denned by a single pulsar is influenced by several noise resources. To weaken these influences, the ensemble analysis method is used to obtain the ensemble pulsar time so that the long-term stability of the ensemble pulsar time can be improved. In this paper, four algorithms — the classical weighted average algorithm, the wavelet analysis algorithm, the Wiener filtration analysis algorithm and the Wiener filtration analysis in wavelet domain — are applied to synthetically make an ensemble pulsar time. The data used are the residuals of the two millisecond pulsars (PSR B1855+09 and PSR B1937+21) observed by Arecibo Observatory. First, the classical weighted average algorithm is developed by Petit, in which only one weight can be chosen within the whole interval of the observation on each single pulsar time, and the criterion for weight is the stability σ_x~2(T) of each single pulsar time. Second, an ensemble pulsar time algorithm is developed based on the wavelet multi-resolution analysis and the wavelet packet analysis, which can be obtained by decomposing the observation residuals of pulsars, extracting the components of different frequency domain and then choosing the weight according to the stability of different component denoted with wavelet variance. Third, the pulsar timing residuals are caused by reference atomic clock and pulsar itself, which are uncorrelated. Considering this uncorrelation and the peculiarity of Wiener filtration, we put forward an ensemble pulsar time algorithm of Wiener filtration. Using this algorithm, the error can be separated from an atomic clock and the pulsar itself in the post-fit pulsar timing residuals. The atomic scale component can be filtered from the pulsar phase variations and the remains can be integrated to the ensemble pulsar time. Weights are chosen according to the mean square root. Forth, the wavelet analysis and the

  18. Non-thermal radiation from a pulsar wind interacting with an inhomogeneous stellar wind

    Science.gov (United States)

    de la Cita, V. M.; Bosch-Ramon, V.; Paredes-Fortuny, X.; Khangulyan, D.; Perucho, M.

    2017-02-01

    Context. Binaries hosting a massive star and a non-accreting pulsar are powerful non-thermal emitters owing to the interaction of the pulsar and the stellar wind. The winds of massive stars are thought to be inhomogeneous, which could have an impact on the non-thermal emission. Aims: We study numerically the impact of the presence of inhomogeneities or clumps in the stellar wind on the high-energy non-thermal radiation of high-mass binaries hosting a non-accreting pulsar. Methods: We compute the trajectories and physical properties of the streamlines in the shocked pulsar wind without clumps, with a small clump, and with a large clump. This information is used to characterize the injection and the steady state distribution of non-thermal particles accelerated at shocks formed in the pulsar wind. The synchrotron and inverse Compton emission from these non-thermal particles is calculated, accounting also for the effect of gamma-ray absorption through pair creation. A specific study is done for PSR B1259-63/LS2883. Results: When stellar wind clumps perturb the two-wind interaction region, the associated non-thermal radiation in the X-ray band, of synchrotron origin, and in the GeV-TeV band, of inverse Compton origin, is affected by several equally important effects: (i) strong changes in the plasma velocity direction that result in Doppler boosting factor variations; (ii) strengthening of the magnetic field that mainly enhances the synchrotron radiation; (iii) strengthening of the pulsar wind kinetic energy dissipation at the shock, potentially available for particle acceleration; and (iv) changes in the rate of adiabatic losses that affect the lower energy part of the non-thermal particle population. The radiation above 100 GeV detected, presumably, during the post-periastron crossing of the Be star disc in PSR B1259-63/LS2883, can be roughly reproduced assuming that the crossing of the disc is modelled as the encounter with a large inhomogeneity. Conclusions

  19. Formation of the planet around the millisecond pulsar J1719-1438

    CERN Document Server

    van Haaften, L M; Voss, R; Jonker, P G

    2012-01-01

    Context. Recently the discovery of PSR J1719-1438, a 5.8 ms pulsar with a companion in a 2.2 hr orbit, was reported. The combination of this orbital period and the very low mass function is unique. The discoverers, Bailes et al., proposed an ultracompact X-ray binary (UCXB) as the progenitor system. However, the standard UCXB scenario would not produce this system as the time required to reach this orbital period exceeds the current estimate of the age of the Universe. The detached state of the system aggravates the problem. Aims. We want to understand the evolutionary history of PSR J1719-1438, and determine under which circumstances it could have evolved from an UCXB. Methods. We model UCXB evolution varying the donor size and investigate the effect of a wind mass loss from the donor, and compare the results with the observed characteristics of PSR J1719-1438. Results. An UCXB can reach a 2.2 hr orbit within the age of the Universe, provided that 1) the millisecond pulsar can significantly heat and expand t...

  20. X-ray studies of the redback system PSR J2129-0429

    Science.gov (United States)

    Noori, Hind Al; Roberts, Mallory; Hessels, Jason; McLaughlin, Maura; Breton, Rene

    2016-04-01

    We present new NuStar data of the redback millisecond pulsar (MSP) system PSR J2129-0429. Redback systems are important when it comes to understanding the evolution of MSPs, in terms of pulsar recycling, as they have been observed to transition between a state of accretion, where emission is in the optical and X-ray regimes, and a state of eclipsed radio pulsation. This system is particularly interesting due to some peculiarities: it has a more massive companion as well as a stronger magnetic field than other redbacks, indicating that the system is in a fairly early stage of recycling. It’s X-ray lightcurve (as obtained from XMM-Newton data) has a very hard power-law component and exhibits an efficiency of a few percent in X-ray. With the NuStar data, the spectrum can be seen to extend to ~30 keV. Additionally, it shows strong orbital variation, about 5 times greater than is typical for other systems, and is also very clearly double peaked. Hints of similar peaks have been observed in the lightcurves of other redback systems, and so this system can help in understanding the intrabinary shock of eclipsing MSPs.

  1. Examining the hard X-ray emission of the redback PSR J2129-0429

    Science.gov (United States)

    Noori, Hind Al; Roberts, Mallory; McLaughlin, Maura; Hessels, Jason; Breton, Rene; 17077031498

    2016-06-01

    We present new NuStar data of the redback millisecond pulsar (MSP) system PSR J2129-0429. Redback systems are important when it comes to understanding the evolution of MSPs, in terms of pulsar recycling, as they have been observed to transition between a state of accretion, where emission is in the optical and X-ray regimes, and a state of eclipsed radio pulsation. This system is particularly interesting due to some peculiarities: it has a more massive companion as well as a stronger magnetic field than other redbacks, indicating that the system is in a fairly early stage of recycling. It’s X-ray lightcurve (as obtained from XMM-Newton data) has a very hard power-law component and exhibits an efficiency of a few percent in X-ray. With the NuStar data, the spectrum can be seen to extend to ~30 keV. Additionally, it shows strong orbital variation, about 5 times greater than is typical for other systems, and is also very clearly double peaked. Hints of similar peaks have been observed in the lightcurves of other redback systems; hence, this system can help in understanding the intrabinary shock of eclipsing MSPs.

  2. On the free-precession candidate PSR B1828-11: Evidence for increasing deformation

    CERN Document Server

    Ashton, G; Prix, R

    2016-01-01

    We observe that the periodic variations in spin-down rate and beam-width of the radio pulsar PSR B1828-11 are getting faster. In the context of a free precession model, this corresponds to a decrease in the precession period $P_{\\mathrm{fp}}$. We investigate how a precession model can account for such a decrease in $P_{\\mathrm{fp}}$, in terms of an increase over time in the absolute biaxial deformation ($|\\epsilon_{\\mathrm{p}}|{\\sim}10^{-8}$) of this pulsar. We perform a Bayesian model comparison against the 'base' precession model (with constant $\\epsilon_{\\mathrm{p}}$) developed in Ashton et al (2016), and we obtain decisive odds in favour of a time-varying deformation. We study two types of time-variation: (i) a linear drift with a posterior estimate of $\\dot{\\epsilon}_{\\mathrm{p}}{\\sim}10^{-18}\\,\\mathrm{s}^{-1}$ and odds of $10^{75}$ compared to the base-model, and (ii) $N$ discrete positive jumps in $\\epsilon_{\\mathrm{p}}$ with very similar odds to the linear $\\epsilon_{\\mathrm{p}}$-drift model. The phys...

  3. Modelling the multiwavelength light curves of PSR B1259-63/SS 2883

    Science.gov (United States)

    Kong, S. W.; Yu, Y. W.; Huang, Y. F.; Cheng, K. S.

    2011-09-01

    PSR B1259-63/SS 2883 is a binary system in which a 48-ms pulsar orbits around a Be star in a high-eccentric orbit with a long orbital period of about 3.4 yr. Extensive broad-band observational data are available for this system from the radio band to very high energy (VHE) range. The multifrequency emission is unpulsed and non-thermal, and is generally thought to be related to the relativistic electrons accelerated from the interaction between the pulsar wind and the stellar wind, whereas X-ray emission is from the synchrotron process and the VHE emission is from the inverse Compton scattering process. Here a shocked wind model with variation in the magnetization parameter σ is developed for explaining the observations. By choosing proper parameters, our model could reproduce a two-peak profile in X-ray and TeV light curves. The effect of the disc exhibits an emission and an absorption component in the X-ray and TeV bands, respectively. We suggest that some GeV flares will be produced by Doppler boosting the synchrotron spectrum. This model can possibly be used and be checked in other similar systems, such as LS I+61°303 and LS 5039.

  4. The Parallax, Mass and Age of the PSR J2145-0750 binary system

    CERN Document Server

    Löhmer, O; Driebe, T; Jessner, A; Mitra, D; Lyne, A G

    2004-01-01

    We present results of timing measurements of the binary millisecond pulsar PSR J2145-0750. Combining timing data obtained with the Effelsberg and Lovell radio telescopes we measure a significant timing parallax of 2.0(6) mas placing the system at 500 pc distance to the solar system. The detected secular change of the projected semi-major axis of the orbit $\\dot x=1.8(6)\\times 10^{-14}$ lt-s s$^{-1}$, where $x=(a_{\\rm p}\\sin i)/c$, is caused by the proper motion of the system. With this measurement we can constrain the orbital inclination angle to $i<61\\degr$, with a median likelihood value of $46\\degr$ which is consistent with results from polarimetric studies of the pulsar magnetosphere. This constraint together with the non-detection of Shapiro delay rules out certain combinations of the companion mass, $m_2$, and the inclination, $i$. For typical neutron star masses and using optical observations of the carbon/oxygen-core white dwarf we derive a mass range for the companion of $0.7 M_\\odot\\leq m_2\\leq 1...

  5. On the free-precession candidate PSR B1828-11: Evidence for increasing deformation

    Science.gov (United States)

    Ashton, G.; Jones, D. I.; Prix, R.

    2017-01-01

    We observe that the periodic variations in spin-down rate and beam-width of the radio pulsar PSR B1828-11 are getting faster. In the context of a free precession model, this corresponds to a decrease in the precession period Pfp. We investigate how a precession model can account for such a decrease in Pfp, in terms of an increase over time in the absolute biaxial deformation (|ɛp| ˜ 10-8) of this pulsar. We perform a Bayesian model comparison against the `base' precession model (with constant ɛp) developed in Ashton et al. (2016), and we obtain decisive odds in favour of a time-varying deformation. We study two types of time-variation: (i) a linear drift with a posterior estimate of dot{ɛ }_p{˜ }10^{-18} s^{-1} and odds of 1075 compared to the base-model, and (ii) N discrete positive jumps in ɛp with very similar odds to the linear ɛp-drift model. The physical mechanism explaining this behaviour is unclear, but the observation could provide a crucial probe of the interior physics of neutron stars. We also place an upper bound on the rate at which the precessional motion is damped, and translate this into a bound on a dissipative mutual friction-type coupling between the star's crust and core.

  6. Modeling the multi-wavelength light curves of PSR B1259-63/SS 2883

    CERN Document Server

    Kong, S W; Huang, Y F; Cheng, K S

    2011-01-01

    PSR B1259-63/SS 2883 is a binary system in which a 48-ms pulsar orbits around a Be star in a high eccentric orbit with a long orbital period of about 3.4 yr. Extensive broadband observational data are available for this system from radio band to very high energy (VHE) range. The multi-frequency emission is unpulsed and nonthermal, and is generally thought to be related to the relativistic electrons accelerated from the interaction between the pulsar wind and the stellar wind, where X-ray emission is from the synchrotron process and the VHE emission is from the inverse Compton (IC) scattering process. Here a shocked wind model with variation of the magnetic parameter $\\sigma$ is developed for explaining the observations. By choosing proper param- eters, our model could reproduce two-peak profile in X-ray and TeV light curves. The effect of the disk exhibits an emission and an absorption components in the X-ray and TeV bands respectively. We suggest that some GeV flares will be produced by Doppler boosting the ...

  7. Youngest Radio Pulsar Revealed with Green Bank Telescope

    Science.gov (United States)

    2002-04-01

    times weaker than that from the famous pulsar in the Crab Nebula (the remnant of an explosion in the year 1054 recorded by Chinese astronomers and possibly also by Native Americans of the Anasazi tribe in modern-day Arizona and New Mexico). "Although we knew what we were looking for," said Camilo "it took the new Green Bank Telescope with its unmatched sensitivity -- and, importantly, location in the National Radio Quiet Zone -- to make this remarkable detection." A pulsar is formed when a massive star runs out of nuclear fuel and dies in a cataclysmic explosion called a supernova. The outer layers of the star are blown off into space, and are often seen as an expanding remnant shell of hot gas. The core of the star, with 40 percent more mass than our Sun, collapses under its own gravity to a sphere only about 10 miles in diameter, composed mostly of neutrons. These densest objects known in the Universe typically are born spinning very rapidly; the newly detected pulsar, known as PSR J0205+6449, presently rotates 15 times every second. Pulsar Diagram Pulsar Diagram: Click on image for more detail. The spinning neutron star has very powerful magnetic and electric fields that accelerate electrons and other subatomic particles, causing them to emit beams of radio waves, X-rays, and other forms of radiation. If these beams intersect the Earth as the star rotates, we can then detect the pulsar, as it appears to flash on-and-off, much like a lighthouse. As the pulsar ages, it gradually slows down and loses its rotational energy. After a few million years it is no longer powerful enough to generate radio emission and "turns-off." By detecting this pulsar in the radio spectrum, astronomers may now follow its evolution with greater ease and flexibility than with X-ray telescopes on satellites, study the pulsar emission mechanisms, and also characterize the dynamic interstellar medium between the Earth and the pulsar. "Finding a radio pulsar this young could be somewhat of a gold

  8. RADIO-QUIET AND RADIO-LOUD PULSARS: SIMILAR IN GAMMA-RAYS BUT DIFFERENT IN X-RAYS

    Energy Technology Data Exchange (ETDEWEB)

    Marelli, M.; Mignani, R. P.; Luca, A. De; Salvetti, D. [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133, Milano (Italy); Parkinson, P. M. Saz [Santa Cruz Institute for Particle Physics, Department of Physics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Hartog, P. R. Den [Stanford University HEPL/KIPAC, 452 Lomita Mall, Stanford, CA 94305-4085 (United States); Wolff, M. T., E-mail: marelli@iasf-milano.inaf.it [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)

    2015-04-01

    We present new Chandra and XMM-Newton observations of a sample of eight radio-quiet (RQ) γ-ray pulsars detected by the Fermi Large Area Telescope. For all eight pulsars we identify the X-ray counterpart, based on the X-ray source localization and the best position obtained from γ-ray pulsar timing. For PSR J2030+4415 we found evidence for a ∼10″-long pulsar wind nebula. Our new results consolidate the work from Marelli et al. and confirm that, on average, the γ-ray-to-X-ray flux ratios (F{sub γ}/F{sub X}) of RQ pulsars are higher than for the radio-loud (RL) ones. Furthermore, while the F{sub γ}/F{sub X} distribution features a single peak for the RQ pulsars, the distribution is more dispersed for the RL ones, possibly showing two peaks. We discuss possible implications of these different distributions based on current models for pulsar X-ray emission.

  9. Radio-quiet and radio-loud pulsars: similar in Gamma-rays but different in X-rays

    CERN Document Server

    Marelli, M; De Luca, A; Parkinson, P M Saz; Salvetti, D; Hartog, P R Den; Wolff, M T

    2015-01-01

    We present new Chandra and XMM-Newton observations of a sample of eight radio-quiet Gamma-ray pulsars detected by the Fermi Large Area Telescope. For all eight pulsars we identify the X-ray counterpart, based on the X-ray source localization and the best position obtained from Gamma-ray pulsar timing. For PSR J2030+4415 we found evidence for an about 10 arcsec-long pulsar wind nebula. Our new results consolidate the work from Marelli et al. 2011 and confirm that, on average, the Gamma-ray--to--X-ray flux ratios (Fgamma/Fx) of radio-quiet pulsars are higher than for the radio-loud ones. Furthermore, while the Fgamma/Fx distribution features a single peak for the radio-quiet pulsars, the distribution is more dispersed for the radio-loud ones, possibly showing two peaks. We discuss possible implications of these different distributions based on current models for pulsar X-ray emission.

  10. Discovery of the Optical/Ultraviolet/Gamma-ray Counterpart to the Eclipsing Millisecond Pulsar J1816+4510

    CERN Document Server

    Kaplan, D L; Ransom, S M; Roberts, M S E; Kotulla, R; Archibald, A M; Biwer, C M; Boyles, J; Dartez, L; Day, D F; Ford, A J; Garcia, A; Hessels, J W T; Jenet, F A; Karako, C; Kaspi, V M; Kondratiev, V I; Lorimer, D R; Lynch, R S; McLaughlin, M A; Rohr, M D W; Siemens, X; Stairs, I H; van Leeuwen, J

    2012-01-01

    The energetic, eclipsing millisecond pulsar J1816+4510 was recently discovered in a low-frequency radio survey with the Green Bank Telescope. With an orbital period of 8.7 hr and minimum companion mass of 0.16 Msun it appears to belong to an increasingly important class of pulsars that are ablating their low-mass companions. We report the discovery of the gamma-ray counterpart to this pulsar, and present a likely optical/ultraviolet counterpart as well. Using the radio ephemeris we detect pulsations in the unclassified gamma-ray source 2FGL J1816.5+4511, implying an efficiency of ~25% in converting the pulsar's spin-down luminosity into gamma-rays and adding PSR J1816+4510 to the large number of millisecond pulsars detected by Fermi. The likely optical/UV counterpart was identified through position coincidence (15,000 K it would be among the brightest and hottest of low-mass pulsar companions, and appears qualitatively different from other eclipsing pulsar systems. In particular, current data suggest that it ...

  11. Timing Observations of PSR J1023+0038 During a Low-mass X-Ray Binary State

    Science.gov (United States)

    Jaodand, Amruta; Archibald, Anne M.; Hessels, Jason W. T.; Bogdanov, Slavko; D’Angelo, Caroline R.; Patruno, Alessandro; Bassa, Cees; Deller, Adam T.

    2016-10-01

    Transitional millisecond pulsars (tMSPs) switch, on roughly multi-year timescales, between rotation-powered radio millisecond pulsar (RMSP) and accretion-powered low-mass X-ray binary (LMXB) states. The tMSPs have raised several questions related to the nature of accretion flow in their LMXB state and the mechanism that causes the state switch. The discovery of coherent X-ray pulsations from PSR J1023+0038 (while in the LMXB state) provides us with the first opportunity to perform timing observations and to compare the neutron star’s spin variation during this state to the measured spin-down in the RMSP state. Whereas the X-ray pulsations in the LMXB state likely indicate that some material is accreting onto the neutron star’s magnetic polar caps, radio continuum observations indicate the presence of an outflow. The fraction of the inflowing material being ejected is not clear, but it may be much larger than that reaching the neutron star’s surface. Timing observations can measure the total torque on the neutron star. We have phase-connected nine XMM-Newton observations of PSR J1023+0038 over the last 2.5 years of the LMXB state to establish a precise measurement of spin evolution. We find that the average spin-down rate as an LMXB is 26.8 ± 0.4% faster than the rate (‑2.39 × 10‑15 Hz s‑1) determined during the RMSP state. This shows that negative angular momentum contributions (dipolar magnetic braking, and outflow) exceed positive ones (accreted material), and suggests that the pulsar wind continues to operate at a largely unmodified level. We discuss implications of this tight observational constraint in the context of possible accretion models.

  12. Wide Band Artificial Pulsar

    Science.gov (United States)

    Parsons, Zackary

    2017-01-01

    The Wide Band Artificial Pulsar (WBAP) is an instrument verification device designed and built by the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virgina. The site currently operates the Green Bank Ultimate Pulsar Processing Instrument (GUPPI) and the Versatile Green Bank Astronomical Spectrometer (VEGAS) digital backends for their radio telescopes. The commissioning and continued support for these sophisticated backends has demonstrated a need for a device capable of producing an accurate artificial pulsar signal. The WBAP is designed to provide a very close approximation to an actual pulsar signal. This presentation is intended to provide an overview of the current hardware and software implementations and to also share the current results from testing using the WBAP.

  13. Pulsars and Extreme Physics

    Science.gov (United States)

    Bell-Burnell, Jocelyn

    2004-10-01

    Pulsars were discovered 35 years ago. What do we know about them now, and what have they taught us about the extremes of physics? With an average density comparable to that of the nucleus, magnetic fields around 108 T and speeds close to c these objects have stretched our understanding of the behaviour of matter. They serve as extrememly accurate clocks with which to carry out precision experiments in relativity. Created in cataclysmic explosions, pulsars are a (stellar) form of life after death. After half a billion revolutions most pulsars finally die, but amazingly some are born again to yet another, even weirder, afterlife. Pulsar research continues lively, delivering exciting, startling and almost unbelievable results!

  14. Pulse Portraiture: Pulsar timing

    Science.gov (United States)

    Pennucci, Timothy T.; Demorest, Paul B.; Ransom, Scott M.

    2016-06-01

    Pulse Portraiture is a wideband pulsar timing code written in python. It uses an extension of the FFTFIT algorithm (Taylor 1992) to simultaneously measure a phase (TOA) and dispersion measure (DM). The code includes a Gaussian-component-based portrait modeling routine. The code uses the python interface to the pulsar data analysis package PSRCHIVE (ascl:1105.014) and also requires the non-linear least-squares minimization package lmfit (ascl:1606.014).

  15. Pulsar Timing Arrays

    OpenAIRE

    Joshi, Bhal Chandra

    2013-01-01

    In the last decade, the use of an ensemble of radio pulsars to constrain the characteristic strain caused by a stochastic gravitational wave background has advanced the cause of detection of very low frequency gravitational waves significantly. This electromagnetic means of gravitational wave detection, called Pulsar Timing Array(PTA), is reviewed in this article. The principle of operation of PTA, the current operating PTAs and their status is presented along-with a discussion of the main ch...

  16. X-ray pulsar signal detection using photon interarrival time

    Institute of Scientific and Technical Information of China (English)

    Qiang Xie; Luping Xu; Hua Zhang

    2013-01-01

    The distribution probability of the photon interarrival time (PIT) without signal initial phases is derived based on the Poisson model of X-ray pulsar signals, and a pulsar signal detec-tion algorithm employing the PIT sequence is put forward. The joint probability of the PIT sequence is regarded as a function of the distribution probability and used to compare a constant radiation intensity model with the nonhomogeneous Poisson model for the signal detection. The relationship between the number of detected photons and the probabilities of false negative and positive is stu-died, and the success rate and mean detection time are estimated based on the number of the given photons. For the spacecraft ve-locity data detection, the changes of time of photon arrival (TOPA) and PIT caused by spacecraft motion are presented first, then the influences on detection are analyzed respectively. By using the analytical pulse profile of PSR B0531+21, the simulation of the X-ray pulsar signal detection is implemented. The simulation results verify the effectiveness of the proposed method, and the contrast tests show that the proposed method is suitable for the spacecraft velocity data detection.

  17. A model for abrupt changes in pulsar pulse profile

    Science.gov (United States)

    Yuen, R.; Melrose, D. B.

    2017-08-01

    We propose and explore a purely magnetospheric model for observed abrupt changes in pulsar radio profile. The flow rate of the magnetospheric plasma is dependent on the magnetospheric state described by the parameter y. We include the effect of the motion of the visible point along its trajectory, whose omission from a 'standard' version of viewing geometry is strictly valid only for align rotation and approximately valid for oblique rotation only in a narrow range of pulsar phase, which decreases as the obliquity increases. Emission is assumed from spots, distributed uniformly around the magnetic axis, so that observable features, such as subpulses, appear to rotate at a rate, ωR, relative to the visible point. We find that the apparent motion of an individual spot is not constant, and the apparent distribution of emission spots around the trajectory of the visible point is uneven being highest around the centre of the pulse window, where their apparent motion is slowest, allowing more spots to be present simultaneously in the pulse window than in the 'standard' version. An abrupt (or more gradual) change in y implies a change in ωR, which affects the pulse structure and profile. As a case study, we apply the model to 'swooshing' in PSR B0919+06. We discuss correlated slowing down rate in the model and related time-dependent phenomena in radio pulsars.

  18. An alternative technique for timing the double pulsar system

    CERN Document Server

    Liang, Zhu-Xing

    2012-01-01

    Freire et al. (2009, MNRAS, 396, 1764) have put forward a technique for timing the double pulsar system PSR J0737-3039A/B (hereafter A and B, respectively). Their technique can be used to determine the sense of rotation of A relative to its orbital plane. In this paper, we present another technique with the same purpose. Two well-known periods, the sidereal day and solar day, are often used to define the spin period of the earth. Their difference is caused by a kinematic effect which correlated with earth's rotation and revolution. We think that this kinematic effect should exist in the double pulsar system and can be used to determine the sense of rotation of the pulsars. Commonly, B's modulation frequency is considered to be equal to A's rotation frequency, because B's signal is modulated by A's energy flux. When the kinematic effect is considered, B's modulation frequency will be, similar to the solar day and sidereal day, a little higher or lower than A's rotation frequency. If this frequency offset can b...

  19. Measuring pulse times of arrival from broadband pulsar observations

    CERN Document Server

    Liu, K; Cognard, I; Stappers, B W; Verbiest, J P W; Lee, K J; Champion, D J; Kramer, M; Freire, P C C; Karuppusamy, R

    2014-01-01

    In recent years, instrumentation enabling pulsar observations with unprecedentedly high fractional bandwidth has been under development which can be used to substantially improve the precision of pulsar timing experiments. The traditional template-matching method used to calculate pulse times-of-arrival (ToAs), may not function effectively on these broadband data due to a variety of effects such as diffractive scintillation in the interstellar medium, profile variation as a function of frequency, dispersion measure (DM) evolution and so forth. In this paper, we describe the channelised Discrete Fourier Transform method that can greatly mitigate the influence of the aforementioned effects when measuring ToAs from broadband timing data. The method is tested on simulated data, and its potential in improving timing precision is shown. We further apply the method to PSR J1909$-$3744 data collected at the Nan\\c{c}ay Radio Telescope with the Nan\\c{c}ay Ultimate Pulsar Processing Instrument. We demonstrate a removal ...

  20. Revised Pulsar Spindown

    CERN Document Server

    Contopoulos, I; Contopoulos, Ioannis; Spitkovsky, Anatoly

    2005-01-01

    We address the issue of electromagnetic pulsar spindown by combining our experience from the two limiting idealized cases which have been studied in great extent in the past: that of an aligned rotator where ideal MHD conditions apply, and that of a misaligned rotator in vacuum. We construct a spindown formula that takes into account the misalignment of the magnetic and rotation axes, and the magnetospheric particle acceleration gaps. We show that near the death line aligned rotators spin down much slower than orthogonal ones. In order to test this approach, we use a simple Monte Carlo method to simulate the evolution of pulsars and find a good fit to the observed pulsar distribution in the P-Pdot diagram without invoking magnetic field decay. Our model may also account for individual pulsars spinning down with braking index n 3, and that the older pulsar population has preferentially smaller magnetic inclination angles. We discuss possible signatures of such alignment in the existing pulsar data.

  1. Prospects for Probing Strong Gravity with a Pulsar-Black Hole System

    Science.gov (United States)

    Wex, N.; Liu, K.; Eatough, R. P.; Kramer, M.; Cordes, J. M.; Lazio, T. J. W.

    2012-01-01

    The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems.

  2. Prospects for Probing Strong Gravity with a Pulsar-Black Hole System

    Science.gov (United States)

    Wex, N.; Liu, K.; Eatough, R. P.; Kramer, M.; Cordes, J. M.; Lazio, T. J. W.

    2012-01-01

    The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems.

  3. The Attenuation of $\\gamma$-Ray Emission in Strongly-Magnetized Pulsars

    CERN Document Server

    Baring, M G; Gonthier, P L; Baring, Matthew G.; Harding, Alice K.; Gonthier, Peter L.

    1997-01-01

    Gamma-rays from pulsars can be efficiently attenuated in their magnetospheres via the mechanism of single-photon pair production and also the exotic QED process of photon splitting, which become prolific in fields approaching the quantum critical value of $B_{cr}=4.41\\times 10^{13}$ Gauss. Recently we have published results of our modelling of strongly-magnetized $\\gamma$-ray pulsars, which focused on the escape or attenuation of photons emitted near the pole at the neutron star surface in dipole fields, in a Schwarzschild metric. We found that pair production and splitting totally inhibit emission above around 10--30 MeV in PSR1509-58, whose surface field is inferred to be as high as $0.7B_{cr}$. Our model pulsar spectra are consistent with the EGRET upper limits for PSR1509-58 for a wide range of polar cap sizes. Here we review the principal predictions of our attenuation analysis, and identify how its powerful observational diagnostic capabilities relate to current and future gamma-ray experiments. Diagnos...

  4. Radioastronomie d'amateur, détection de pulsars a 21 cm

    Science.gov (United States)

    Maintoux, Jean-Jacques

    2017-01-01

    Since the discovery of PSR B1919+21 in 1967, the study of radio pulsars has been so far the work of professional teams using large aperture arrays or single dish antennas. While the discovery of new pulsars is so far out of reach of amateurs astronomers with limited resources, we report the successful detection of 3 pulsars at 1420MHz with a 3.3m prime focus dish antenna, namely: B0329+54, B0950+08 and B1133+16. According to the Neutron Star list [6], this sets a new detection record given the very limited aperture of the antenna. In this paper, we expose how the sensibility and stability to achieve such detection was obtained with our constrained setup, then we discuss the data processing aspects, including the period calculation and folding for each PSR, as well as pulse profiles. With the upcoming upgrades to the telescope, more detections are likely to come. An ongoing observation of B2020+28 already yields promising results. Follow the last results here : http://www.f1ehn.org "radioastro"

  5. THE DOUBLE PULSAR: EVIDENCE FOR NEUTRON STAR FORMATION WITHOUT AN IRON CORE-COLLAPSE SUPERNOVA

    Energy Technology Data Exchange (ETDEWEB)

    Ferdman, R. D.; Kramer, M.; Stappers, B. W.; Lyne, A. G. [School of Physics and Astronomy, University of Manchester, Jodrell Bank Centre for Astrophysics, Alan Turing Building, Oxford Road, Manchester M13 9PL (United Kingdom); Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Breton, R. P. [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); McLaughlin, M. A. [Department of Physics, West Virginia University, Morgantown, WV 26505 (United States); Freire, P. C. C. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Possenti, A. [INAF-Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, I-09012 Capoterra (Italy); Kaspi, V. M. [Department of Physics, McGill University, Ernest Rutherford Physics Building, 3600 University Street, Montreal, QC H3A 2T8 (Canada); Manchester, R. N., E-mail: ferdman@jb.man.ac.uk [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping, NSW 1710 (Australia)

    2013-04-10

    The double pulsar system PSR J0737-3039A/B is a double neutron star binary, with a 2.4 hr orbital period, which has allowed measurement of relativistic orbital perturbations to high precision. The low mass of the second-formed neutron star, as well as the low system eccentricity and proper motion, point to a different evolutionary scenario compared to most other known double neutron star systems. We describe analysis of the pulse profile shape over 6 years of observations and present the resulting constraints on the system geometry. We find the recycled pulsar in this system, PSR J0737-3039A, to be a near-orthogonal rotator with an average separation between its spin and magnetic axes of 90 Degree-Sign {+-} 11 Degree-Sign {+-} 5 Degree-Sign . Furthermore, we find a mean 95% upper limit on the misalignment between its spin and orbital angular momentum axes of 3. Degree-Sign 2, assuming that the observed emission comes from both magnetic poles. This tight constraint lends credence to the idea that the supernova that formed the second pulsar was relatively symmetric, possibly involving electron capture onto an O-Ne-Mg core.

  6. The double pulsar: evidence for neutron star formation without an iron core-collapse supernova

    CERN Document Server

    Ferdman, R D; Kramer, M; Breton, R P; McLaughlin, M A; Freire, P C C; Possenti, A; Stappers, B W; Kaspi, V M; Manchester, R N; Lyne, A G

    2013-01-01

    The double pulsar system PSR J0737-3039A/B is a double neutron star binary, with a 2.4-hour orbital period, which has allowed measurement of relativistic orbital perturbations to high precision. The low mass of the second-formed neutron star, as well as the low system eccentricity and proper motion, point to a different evolutionary scenario compared to most other known double neutron star systems. We describe analysis of the pulse profile shape over 6 years of observations, and present the resulting constraints on the system geometry. We find the recycled pulsar in this system, PSR J0737-3039A, to be a near-orthogonal rotator, with an average separation between its spin and magnetic axes of 90 +/- 11 +/- 5 deg. Furthermore, we find a mean 95% upper limit on the misalignment between its spin and orbital angular momentum axes of 3.2 deg, assuming that the observed emission comes from both magnetic poles. This tight constraint lends credence to the idea that the supernova that formed the second pulsar was relat...

  7. Coherent Radio Emission from Pulsars

    CERN Document Server

    Mitra, Dipanjan; Gil, Janusz

    2015-01-01

    We review a physical model where the high brightness temperature of 10$^{25}-10^{30}$ K observed in pulsar radio emission is explained by coherent curvature radiation excited in the relativistic electron-positron plasma in the pulsar magnetosphere.

  8. The origin of the X-ray-emitting object moving away from PSR B1259-63

    CERN Document Server

    Barkov, Maxim V

    2015-01-01

    A mysterious X-ray-emitting object has been detected moving away from the high-mass gamma-ray binary PSR B1259-63, which contains a non-accreting pulsar and a Be star whose winds collide forming a complex interaction structure. Given the strong eccentricity of this binary, the interaction structure should be strongly anisotropic, which together with the complex evolution of the shocked winds, could explain the origin of the observed moving X-ray feature. We propose here that a fast outflow made of a pulsar-stellar wind mixture is always present moving away from the binary in the apastron direction, with the injection of stellar wind occurring at orbital phases close to periastron passage. This outflow periodically loaded with stellar wind would move with a high speed, and likely host non-thermal activity due to shocks, on scales similar to those of the observed moving X-ray object. Such an outflow is thus a very good candidate to explain this X-ray feature. This, if confirmed, would imply pulsar-to-stellar wi...

  9. a Surprise from the Pulsar in the Crab Nebula

    Science.gov (United States)

    1995-11-01

    at optical wavelengths and only one is bright enough to allow reasonably detailed spectroscopic observations with currently available optical telescopes. The Crab Pulsar This is the famous Crab Pulsar, also known as PSR 0531+21. It was discovered as a radio pulsar in 1968, soon after the detection of the first known radio pulsar. A little later, pulsed optical emission from the Crab Pulsar was also observed. It was quickly recognized that this emission obeys Pacini's law [2]. Stated in simple terms, this implies that the emission of optical light from the pulsar is due to the interaction between very energetic elementary particles close to the neutron star and its incredibly strong magnetic field. The Crab Pulsar is especially interesting, because we have detailed historical information about the event from which it was born: the very bright `guest star' which was so well observed and described by Chinese astronomers in the year 1054 AD in the constellation of Taurus (the Bull). At the exact location of this supernova is now observed the famous Crab Nebula in which the Crab Pulsar is embedded. The Crab Nebula is a very conspicuous object in the sky (the name alludes to its overall form), and it emits a very significant amount of energy at all wavelengths of the electromagnetic spectrum that have so far been explored, from long-wave radio waves to gamma-rays of ultra-high energy. At X-ray wavelengths (above 1 keV), it is in fact one of the brightest, continuously emitting sources in the sky. The Crab Pulsar also emits at all wavelengths, but it is much fainter than the surrounding nebula. This Press Release is accompanied by a photo with caption, showing the pulsar in the innermost region of the nebula. At optical wavelengths, the Crab Pulsar is a comparatively faint, point-like object of magnitude 16.6. It is interesting to note that, from the measured, outward motion of the individual condensations in the Crab Nebula, this object was recognized, already a decade

  10. Chandra X-ray Observations of 12 Millisecond Pulsars in the Globular Cluster M28

    CERN Document Server

    Bogdanov, Slavko; Servillat, Mathieu; Heinke, Craig O; Grindlay, Jonathan E; Stairs, Ingrid H; Ransom, Scott M; Freire, Paulo C C; Bégin, Steve; Becker, Werner

    2011-01-01

    We present a Chandra X-ray Observatory investigation of the millisecond pulsars (MSPs) in the globular cluster M28 (NGC 6626). In what is one of the deepest X-ray observations of a globular cluster, we firmly detect seven and possibly detect two of the twelve known M28 pulsars. With the exception of PSRs B1821-24 and J1824-2452H, the detected pulsars have relatively soft spectra, with X-ray luminosities 10^30-31 ergs s^-1 (0.3-8 keV),similar to most "recycled" pulsars in 47 Tucanae and the field of the Galaxy, implying thermal emission from the pulsar magnetic polar caps. We present the most detailed X-ray spectrum to date of the energetic PSR B1821-24. It is well described by a purely non-thermal spectrum with spectral photon index 1.23 and luminosity 1.4x10^33Theta(D/5.5 kpc)^2 ergs s^-1 (0.3-8 keV), where Theta is the fraction of the sky covered by the X-ray emission beam(s). We find no evidence for the previously reported line emission feature around 3.3 keV, most likely as a consequence of improvements i...

  11. Thermal properties of the $\\gamma$-ray pulsar J1741$-$2054

    CERN Document Server

    Karpova, A; Shibanov, Yu; Shternin, P; Zyuzin, D

    2014-01-01

    We present results of the spectral analysis of the X-ray emission from the middle-aged Fermi pulsar J1741$-$2054 using all Chandra archival data collected in 2010 and 2013. We confirm early findings by Romani et al. 2010 that the pulsar spectrum contains a thermal emission component. The component is best described by the blackbody model with the temperature $\\approx$ 60 eV and the emitting area radius $\\approx$ 17 $D_{\\rm kpc}$ km. The thermal emission likely originates from the entire surface of the cooling neutron star if the distance to the pulsar is $\\approx$0.8 kpc. The latter is supported by a large absorbing column density inferred from the X-ray fit and empirical optical extinction--distance relations along the pulsar line of sight. The neutron star surface temperature and characteristic age make it similar to the well studied middle-aged pulsar B1055$-$52. Like the latter PSR J1741$-$2054 is hotter than the standard cooling scenario predicts.

  12. The Binary Companion of Young, Relativistic Pulsar J1906+0746

    CERN Document Server

    van Leeuwen, Joeri; Stairs, Ingrid H; Lorimer, D R; Camilo, F; Chatterjee, S; Cognard, I; Desvignes, G; Freire, P C C; Janssen, G H; Kramer, M; Lyne, A G; Nice, D J; Ransom, S M; Stappers, B W; Weisberg, J M

    2014-01-01

    PSR J1906+0746 is a young pulsar in the relativistic binary with the second-shortest known orbital period, of 3.98 hours. We here present a timing study based on five years of observations, conducted with the 5 largest radio telescopes in the world, aimed at determining the companion nature. Through the measurement of three post-Keplerian orbital parameters we find the pulsar mass to be 1.291(11) M_sol, and the companion mass 1.322(11) M_sol respectively. These masses fit well in the observed collection of double neutron stars, but are also compatible with other white dwarfs around young pulsars such as J1906+0746. Neither radio pulsations nor dispersion-inducing outflows that could have further established the companion nature were detected. We derive an HI-absorption distance, which indicates that an optical confirmation of a white dwarf companion is very challenging. The pulsar is fading fast due to geodetic precession, limiting future timing improvements. We conclude that young pulsar J1906+0746 is likely...

  13. THE BINARY COMPANION OF YOUNG, RELATIVISTIC PULSAR J1906+0746

    Energy Technology Data Exchange (ETDEWEB)

    Van Leeuwen, J.; Janssen, G. H. [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo (Netherlands); Kasian, L.; Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Lorimer, D. R. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Camilo, F. [Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612 (United States); Chatterjee, S. [Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement et de l' Espace LPC2E CNRS-Université d' Orléans, F-45071 Orléans (France); Desvignes, G.; Freire, P. C. C.; Kramer, M. [Max-Planck-Institut für Radioastronomie, D-53121 Bonn (Germany); Lyne, A. G.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Nice, D. J. [Department of Physics, Lafayette College, Easton, PA 18042 (United States); Ransom, S. M. [NRAO (National Radio Astronomy Observatory), Charlottesville, VA 22903 (United States); Weisberg, J. M., E-mail: leeuwen@astron.nl [Department of Physics and Astronomy, Carleton College, Northfield, MN 55057 (United States)

    2015-01-10

    PSR J1906+0746 is a young pulsar in the relativistic binary with the second-shortest known orbital period, of 3.98 hr. We here present a timing study based on five years of observations, conducted with the five largest radio telescopes in the world, aimed at determining the companion nature. Through the measurement of three post-Keplerian orbital parameters, we find the pulsar mass to be 1.291(11) M {sub ☉}, and the companion mass 1.322(11) M {sub ☉}, respectively. These masses fit well in the observed collection of double neutron stars (DNSs), but are also compatible with other systems where a young pulsar such as J1906+0746 is orbited by a white dwarf (WD). Neither radio pulsations nor dispersion-inducing outflows that could have further established the companion nature were detected. We derive an H I-absorption distance, which indicates that an optical confirmation of a WD companion is very challenging. The pulsar is fading fast due to geodetic precession, limiting future timing improvements. We conclude that the young pulsar J1906+0746 is likely part of a DNS, or is otherwise orbited by an older WD, in an exotic system formed through two stages of mass transfer.

  14. The Double Pulsar Eclipses I: Phenomenology and Multi-frequency Analysis

    CERN Document Server

    Breton, R P; McLaughlin, M A; Lyutikov, M; Kramer, M; Stairs, I H; Ransom, S M; Ferdman, R D; Camilo, F; Possenti, A

    2012-01-01

    The double pulsar PSR J0737-3039A/B displays short, 30 s eclipses that arise around conjunction when the radio waves emitted by pulsar A are absorbed as they propagate through the magnetosphere of its companion pulsar B. These eclipses offer a unique opportunity to probe directly the magnetospheric structure and the plasma properties of pulsar B. We have performed a comprehensive analysis of the eclipse phenomenology using multi-frequency radio observations obtained with the Green Bank Telescope. We have characterized the periodic flux modulations previously discovered at 820 MHz by McLaughlin et al., and investigated the radio frequency dependence of the duration and depth of the eclipses. Based on their weak radio frequency evolution, we conclude that the plasma in pulsar B's magnetosphere requires a large multiplicity factor (~ 10^5). We also found that, as expected, flux modulations are present at all radio frequencies in which eclipses can be detected. Their complex behavior is consistent with the confin...

  15. A Pulsar and White Dwarf in an Unexpected Orbit

    Science.gov (United States)

    Kohler, Susanna

    2016-11-01

    Astronomers have discovered a binary system consisting of a low-mass white dwarf and a millisecond pulsar but its eccentric orbit defies all expectations of how such binaries form.Observed orbital periods and binary eccentricities for binary millisecond pulsars. PSR J2234+0511 is the furthest right of the green stars that mark the five known eccentric systems. [Antoniadis et al. 2016]Unusual EccentricityIt would take a low-mass (0.4 solar masses) white dwarf over 100 billion years to form from the evolution of a single star. Since this is longer than the age of the universe, we believe that these lightweights are instead products of binary-star evolution and indeed, we observe many of these stars to still be in binary systems.But the binary evolution that can create a low-mass white dwarf includes a period of mass transfer, in which efficient tidal dissipation damps the systems orbital eccentricity. Because of this, we would expect all systems containing low-mass white dwarfs to have circular orbits.In the past, our observations of low-mass white dwarfmillisecond pulsar binaries have all been consistent with this expectation. But a new detection has thrown a wrench in the works: the unambiguous identification of a low-mass white dwarf thats in an eccentric (e=0.13) orbit with the millisecond pulsar PSR J2234+0511. How could this system have formed?Eliminating Formation ModelsLed by John Antoniadis (Dunlap Institute at University of Toronto), a team of scientists has used newly obtained optical photometry (from the Sloan Digital Sky Survey) and spectroscopy (from the Very Large Telescope in Chile) of the white dwarf to confirm the identification of this system.Antoniadis and collaborators then use measurements of the bodies masses (0.28 and 1.4 solar masses for the white dwarf and pulsar, respectively) and velocities, and constraints on the white dwarfs temperature, radius and surface gravity, to address three proposed models for the formation of this system.The 3D

  16. Search for TeV emission from the region around PSR B1706-44 with the H.E.S.S. experiment

    CERN Document Server

    Aharonian, F; Aye, K M; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Berghaus, P; Bernlöhr, K; Boisson, C; Bolz, O; Borgmeier, C; Braun, I; Breitling, F; Brown, A M; Bussons-Gordo, J; Chadwick, P M; Chounet, L M; Cornils, R; Costamante, L; Degrange, B; Djannati-Atai, A; O'Connor-Drury, L; Dubus, G; Ergin, T; Espigat, P; Feinstein, F; Fleury, P; Fontaine, G; Fuchs, Y; Funk, S; Gallant, Y A; Giebels, B; Gillessen, S; Goret, P; Hadjichristidis, C; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hofmann, W; Holleran, M; Horns, D; De Jager, O C; Jung, I; Khelifi, B; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemiere, A; Lemoine, M; Leroy, N; Lohse, T; Marcowith, A; Masterson, C; McComb, T J L; De Naurois, Mathieu; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Raux, J; Rayner, S M; Redondo, I; Reimer, A; Reimer, O; Ripken, J; Rob, L; Rolland, L; Rowell, G; Sahakian, V V; Sauge, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Sol, H; Steenkamp, R; Stegmann, C; Tavernet, J P; Terrier, R; Theoret, C G; Tluczykont, M; Vasileiadis, G; Venter, C; Vincent, P; Visser, B; Völk, H J; Wagner, S J

    2005-01-01

    The region around PSR B1706-44 has been observed with the H.E.S.S. imaging atmospheric Cherenkov telescopes in 2003. No evidence for gamma-ray emission in the TeV range was found at the pulsar position or at the radio arc which corresponds to the supernova remnant G 343.1-2.3. The 99% confidence level flux upper limit at the pulsar position is Ful(E > 350GeV) = 1.4e-12 /cm^2/s assuming a power law with photon index of 2.5 and Ful(E > 500GeV) = 1.3e-12 /cm^2/s without an assumption on the spectral shape. The reported upper limits correspond to 8% of the flux from an earlier detection by the CANGAROO experiment.

  17. Pulse profile stability of the Crab pulsar

    Institute of Scientific and Technical Information of China (English)

    Chetana Jain; Biswajit Paul

    2011-01-01

    We present an X-ray timing analysis of the Crab pulsar,PSR B0531+21,using archival RXTE data.We have investigated the stability of the Crab pulse profile,in soft (2-20keV) and hard (30-100keV) X-ray energies,over the last decade of RXTE operation.The analysis includes measurement of the separation between the two pulse peaks and the intensity and widths of the two peaks.We did not find any significant time dependency in the pulse shape.The two peaks have been stable in phase,intensity and width for the last ten years.The first pulse is relatively stronger at soft X-rays.The first pulse peak is narrower than the second peak in both soft and hard X-ray energies.Both the peaks show a slow rise and a steeper fall.The ratio of the pulsed photons in the two peaks is also constant in time.

  18. Robust fitting for pulsar timing analysis

    Science.gov (United States)

    Wang, Yidi; Keith, Michael J.; Stappers, Benjamin; Zheng, Wei

    2017-07-01

    We introduce a robust fitting method into pulsar timing analysis to cope with the non-Gaussian noise. The general maximum likelihood estimator (M-estimator) can resist the impact of non-Gaussian noise by employing convex and bounded loss functions. Three loss functions, including the Huber function, the Bisquare function and the Welsch function, are investigated. The Shapiro-Wilk test is employed to test whether the uncertainty in the observed times of arrival is drawn from a non-Gaussian distribution. Two simulations, where the non-Gaussian distribution is modelled as contaminated Gaussian distributions, are performed. It is found that M-estimators are unbiased and could achieve a root-mean-square error smaller than that obtained by the least square (LS) at the cost of a slightly higher computation complexity in a non-Gaussian environment. M-estimators are also applied to the real timing data of PSR J1713+0747. The results have shown that the fitting results of M-estimators are more accurate than those of LS and are closer to the result of very long baseline interferometry.

  19. Pulsars: Gigantic Nuclei

    CERN Document Server

    Xu, Renxin

    2011-01-01

    What is the real nature of pulsars? This is essentially a question of the fundamental strong interaction between quarks at low-energy scale and hence of the non-perturbative quantum chromo-dynamics, the solution of which would certainly be meaningful for us to understand one of the seven millennium prize problems (i.e., "Yang-Mills Theory") named by the Clay Mathematical Institute. After a historical note, it is argued here that a pulsar is very similar to an extremely big nucleus, but is a little bit different from the {\\em gigantic nucleus} speculated 80 years ago by L. Landau. The paper demonstrates the similarity between pulsars and gigantic nuclei from both points of view: the different manifestations of compact stars and the general behavior of the strong interaction.

  20. Pulsar virtual observatory

    CERN Document Server

    Keith, M; Lyne, A; Brooke, J

    2007-01-01

    The Pulsar Virtual Observatory will provide a means for scientists in all fields to access and analyze the large data sets stored in pulsar surveys without specific knowledge about the data or the processing mechanisms. This is achieved by moving the data and processing tools to a grid resource where the details of the processing are seen by the users as abstract tasks. By developing intelligent scheduling middle-ware the issues of interconnecting tasks and allocating resources are removed from the user domain. This opens up large sets of radio time-series data to a wider audience, enabling greater cross field astronomy, in line with the virtual observatory concept. Implementation of the Pulsar Virtual Observatory is underway, utilising the UK National Grid Service as the principal grid resource.

  1. Handbook of pulsar astronomy

    CERN Document Server

    Lorimer, Duncan

    2005-01-01

    Radio pulsars are rapidly rotating highly magnetized neutron stars. Studies of these fascinating objects have provided applications in solid-state physics, general relativity, galactic astronomy, astrometry, planetary physics and even cosmology. Most of these applications and much of what we know about neutron stars are derived from single-dish radio observations using state-of-the-art receivers and data acquisition systems. This comprehensive 2004 book is a unique resource that brings together the key observational techniques, background information and a review of results, including the discovery of a double pulsar system. Useful software tools are provided which can be used to analyse example data, made available on a related website. This work will be of great value not only to graduate students but also to researchers wishing to carry out and interpret a wide variety of radio pulsar observations.

  2. Current Flows in Pulsar Magnetospheres

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The global structure of .current flows in pulsar magnetosphere is investigated, with rough calculations of the circuit elements. It is emphasized that the potential of the critical field lines (the field lines that intersect the null surface at the light cylinder radius) should be the same as that of interstellar medium, and that pulsars whose rotation axes and magnetic dipole axes are parallel should be positively charged, in order to close the pulsar's current flows. The statistical relation between the radio luminosity and pulsar's electric charge (or the spindown power) may hint that the millisecond pulsars could be low-mass bare strange stars.

  3. Fermi Study of gamma-ray Millisecond Pulsars: the Spectral Shape and Pulsed 25--200 GeV Emission from J0614-3329

    CERN Document Server

    Xing, Yi

    2016-01-01

    We report our analysis of the Fermi Large Area Telescope data for 39 millisecond pulsars (MSPs) listed in the second $\\gamma$-ray pulsar catalog. Spectra of the pulsars are obtained. We fit the spectra with a function of a power law with exponential cutoff, and find the best-fit parameters of photon index $\\Gamma = 1.54^{+0.10}_{-0.11}$ and cutoff energy $E_{c} = 3.70^{+0.95}_{-0.70}$ GeV. This spectral shape, which includes the intrinsic differences in the spectra of the MSPs, can be used for finding candidate MSPs and unidentified types of sources detected by Fermi at high Galactic latitudes. In one of the MSPs PSR J0614-3329, we find significant pulsed emission upto 200 GeV. The result has thus added this MSP to the group of the Crab and Vela pulsars that have been detected with >50 GeV pulsed emission. Comparing the $\\gamma$-ray spectrum of PSR J0614-3329 with those of the Crab and Vela pulsars, we discuss possible emission mechanisms for the very high-energy component.

  4. The Pulsar Search Collaboratory

    CERN Document Server

    Rosen, Rachel; McLaughlin, Maura A; Lynch, Ryan; Kondratiev, Vlad I; Boyles, Jason R; Wilson, M Terry; Lorimer, Duncan R; Ransom, Scott; 10.3847/AER2010004

    2010-01-01

    The Pulsar Search Collaboratory [PSC, NSF #0737641] is a joint project between the National Radio Astronomy Observatory (NRAO) and West Virginia University (WVU) designed to interest high school students in science, technology, engineering, and mathematics [STEM] related career paths by helping them to conduct authentic scientific research. The 3- year PSC program, which began in summer 2008, teaches students to analyze astronomical radio data acquired with the 100-m Robert C. Byrd Green Bank Telescope for the purpose of discovering new pulsars. We present the results of the first complete year of the PSC, which includes two astronomical discoveries.

  5. Pulsars: Cosmic Permanent 'Neutromagnets'?

    CERN Document Server

    Hansson, Johan

    2011-01-01

    We argue that pulsars may be spin-polarized neutron stars, i.e. cosmic permanent magnets. This would simply explain several observational facts about pulsars, including the 'beacon effect' itself i.e. the static/stable misalignment of rotational and magnetic axes, the extreme temporal stability of the pulses and the existence of an upper limit for the magnetic field strength - coinciding with the one observed in "magnetars". Although our model admittedly is speculative, this latter fact seems to us unlikely to be pure coincidence.

  6. The Braking Index of a Radio-quiet Gamma-Ray Pulsar

    Science.gov (United States)

    Clark, C. J.; Pletsch, H. J.; Wu, J.; Guillemot, L.; Camilo, F.; Johnson, T. J.; Kerr, M.; Allen, B.; Aulbert, C.; Beer, C.; Bock, O.; Cuéllar, A.; Eggenstein, H. B.; Fehrmann, H.; Kramer, M.; Machenschalk, B.; Nieder, L.

    2016-11-01

    We report the discovery and timing measurements of PSR J1208-6238, a young and highly magnetized gamma-ray pulsar, with a spin period of 440 ms. The pulsar was discovered in gamma-ray photon data from the Fermi Large Area Telescope (LAT) during a blind-search survey of unidentified LAT sources, running on the distributed volunteer computing system Einstein@Home. No radio pulsations were detected in dedicated follow-up searches with the Parkes radio telescope, with a flux density upper limit at 1369 MHz of 30 μJy. By timing this pulsar’s gamma-ray pulsations, we measure its braking index over five years of LAT observations to be n = 2.598 ± 0.001 ± 0.1, where the first uncertainty is statistical and the second estimates the bias due to timing noise. Assuming its braking index has been similar since birth, the pulsar has an estimated age of around 2700 years, making it the youngest pulsar to be found in a blind search of gamma-ray data and the youngest known radio-quiet gamma-ray pulsar. Despite its young age, the pulsar is not associated with any known supernova remnant or pulsar wind nebula. The pulsar’s inferred dipolar surface magnetic field strength is 3.8 × 1013 G, almost 90% of the quantum-critical level. We investigate some potential physical causes of the braking index deviating from the simple dipole model but find that LAT data covering a longer time interval will be necessary to distinguish between these.

  7. THE VELA-X PULSAR WIND NEBULA REVISITED WITH FOUR YEARS OF FERMI LARGE AREA TELESCOPE OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Grondin, M.-H. [Max-Planck-Institut fuer Kernphysik, P.O. Box 103980, D-69029 Heidelberg (Germany); Romani, R. W. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Lemoine-Goumard, M.; Reposeur, T. [Universite Bordeaux 1, CNRS/IN2p3, Centre d' Etudes Nucleaires de Bordeaux Gradignan, F-33175 Gradignan (France); Guillemot, L. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Harding, A. K., E-mail: mgrondin@irap.omp.eu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-09-10

    The Vela supernova remnant (SNR) is the closest SNR to Earth containing an active pulsar, the Vela pulsar (PSR B0833-45). This pulsar is an archetype of the middle-aged pulsar class and powers a bright pulsar wind nebula (PWN), Vela-X, spanning a region of 2 Degree-Sign Multiplication-Sign 3 Degree-Sign south of the pulsar and observed in the radio, X-ray, and very high energy {gamma}-ray domains. The detection of the Vela-X PWN by the Fermi Large Area Telescope (LAT) was reported in the first year of the mission. Subsequently, we have reinvestigated this complex region and performed a detailed morphological and spectral analysis of this source using 4 yr of Fermi-LAT observations. This study lowers the threshold for morphological analysis of the nebula from 0.8 GeV to 0.3 GeV, allowing for the inspection of distinct energy bands by the LAT for the first time. We describe the recent results obtained on this PWN and discuss the origin of the newly detected spatial features.

  8. Emission of extremely bright gamma-ray pulsar in the Large Magellanic Cloud

    CERN Document Server

    Machabeli, George

    2016-01-01

    In the present paper a theoretical interpretation of observational characteristics of the pulsar PSR J0540-6919 is suggested. In particular, we provide a theoretical model explaining the presence of two peaks in the radio domain and the brooding of these peaks at higher frequencies. The model also explains the pulse-phase coincidence of emission peaks at different frequencies and shows the physical, 'genetic' connection between the radio remission at frequencies of the order of GHz with gamma-ray emission up to GeV energies.

  9. EVOLUTIONARY TRAJECTORIES OF ULTRACOMPACT 'BLACK WIDOW' PULSARS WITH VERY LOW MASS COMPANIONS

    Energy Technology Data Exchange (ETDEWEB)

    Benvenuto, O. G.; De Vito, M. A. [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata and Instituto de Astrofisica de La Plata (IALP), CCT-CONICET-UNLP, Paseo del Bosque S/N (B1900FWA), La Plata (Argentina); Horvath, J. E., E-mail: obenvenu@fcaglp.unlp.edu.ar, E-mail: adevito@fcaglp.unlp.edu.ar, E-mail: foton@astro.iag.usp.br [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, R. do Matao 1226 (05508-090), Cidade Universitaria, Sao Paulo, SP (Brazil)

    2012-07-10

    The existence of millisecond pulsars with planet-mass companions in close orbits is challenging from the stellar evolution point of view. We calculate in detail the evolution of binary systems self-consistently, including mass transfer, evaporation, and irradiation of the donor by X-ray feedback, demonstrating the existence of a new evolutionary path leading to short periods and compact donors as required by the observations of PSR J1719-1438. We also point out the alternative of an exotic nature of the companion planet-mass star.

  10. Evolutionary trajectories of ultra-compact "black widow" pulsars with very low mass companions

    CERN Document Server

    Benvenuto, O G; Horvath, J E

    2012-01-01

    The existence of millisecond pulsars with planet-mass companions (Bailes et al., 2011) in close orbits is challenging from the stellar evolution point of view. We calculate in detail the evolution of binary systems self-consistently, including mass transfer, evaporation and irradiation of the donor by X-rays feedback, demonstrating the existence of a new evolutionary path leading to short periods and compact donors as required by the observations of PSR J1719-1438. We also point out the alternative of an exotic nature of the companion planet-mass star.

  11. Long-term Observations of Three Nulling Pulsars

    CERN Document Server

    Young, N J; Stappers, B W; Lyne, A G; Kramer, M

    2015-01-01

    We present an analysis of approximately 200 hours of observations of the pulsars J1634$-$5107, J1717$-$4054 and J1853$+$0505, taken over the course of 14.7 yr. We show that all of these objects exhibit long term nulls and radio-emitting phases (i.e. minutes to many hours), as well as considerable nulling fractions (NFs) in the range $\\sim67\\,\\% - 90\\,\\%$. PSR J1717$-$4054 is also found to exhibit short timescale nulls ($1 - 40~P$) and burst phases ($\\lesssim 200~P$) during its radio-emitting phases. This behaviour acts to modulate the NF, and therefore the detection rate of the source, over timescales of minutes. Furthermore, PSR J1853$+$0505 is shown to exhibit a weak emission state, in addition to its strong and null states, after sufficient pulse integration. This further indicates that nulls may often only represent transitions to weaker emission states which are below the sensitivity thresholds of particular observing systems. In addition, we detected a peak-to-peak variation of $33\\pm1\\,\\%$ in the spin-...

  12. Profile shape stability and phase jitter analyses of millisecond pulsars

    CERN Document Server

    Liu, K; Lee, K J; Kramer, M; Cordes, J M; Purver, M B

    2011-01-01

    Millisecond pulsars (MSPs) have been studied in detail since their discovery in 1982. The integrated pulse profiles of MSPs appear to be stable, which enables precision monitoring of the pulse times of arrival (TOAs). However, for individual pulses the shape and arrival phase can vary dramatically, which is known as pulse jitter. In this paper, we investigate the stability of integrated pulse profiles for 5 MSPs, and estimate the amount of jitter for PSR J0437-4715. We do not detect intrinsic profile shape variation based on integration times from ~10 to ~100 s with the provided instrumental sensitivity. For PSR J0437-4715 we calculate the jitter parameter to be f_J=0.067+-0.002, and demonstrate that the result is not significantly affected by instrumental TOA uncertainties. Jitter noise is also found to be independent of observing frequency and bandwidth around 1.4 GHz on frequency scales of <100 MHz, which supports the idea that pulses within narrow frequency scale are equally jittered. In addition, we p...

  13. X-ray variability and evidence for pulsations from the unique radio pulsar/X-ray binary transition object FIRST J102347.6+003841

    NARCIS (Netherlands)

    Archibald, A.M.; Kaspi, V.M.; Bogdanov, S.; Hessels, J.W.T.; Stairs, I.H.; Ransom, S.M.; McLaughlin, M.A.

    2010-01-01

    We report on observations of the unusual neutron-star binary system FIRST J102347.6+003841 carried out using the XMM-Newton satellite. This system consists of a radio millisecond pulsar (PSR J1023+0038) in a 0.198 day orbit with a ~0.2 M sun Roche-lobe-filling companion and appears to have had an ac

  14. SINGLE-PULSE RADIO OBSERVATIONS OF THE GALACTIC CENTER MAGNETAR PSR J1745–2900

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Zhen; Shen, Zhi-Qiang; Wu, Ya-Jun; Zhao, Rong-Bing; Fan, Qing-Yuan; Hong, Xiao-Yu; Jiang, Dong-Rong; Li, Bin; Liang, Shi-Guang; Ling, Quan-Bao; Liu, Qing-Hui; Qian, Zhi-Han; Zhang, Xiu-Zhong; Zhong, Wei-Ye; Ye, Shu-Hua [Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China); Wu, Xin-Ji [Department of Astronomy, Peking University, Beijing 100871 (China); Manchester, R. N. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Weltevrede, P. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Yuan, Jian-Ping [Key Laboratory of Radio Astronomy, Chinese Academy of Sciences (China); Lee, Ke-Jia, E-mail: yanzhen@shao.ac.cn [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)

    2015-11-20

    In this paper, we report radio observations of the Galactic Center magnetar PSR J1745–2900 at six epochs between 2014 June and October. These observations were carried out using the new Shanghai Tian Ma Radio Telescope at a frequency of 8.6 GHz. Both the flux density and integrated profile of PSR J1745–2900 show dramatic changes from epoch to epoch, showing that the pulsar was in its “erratic” phase. On MJD 56836, the flux density of this magnetar was about 8.7 mJy, which was 10 times larger than that reported at the time of discovery, enabling a single-pulse analysis. The emission is dominated by narrow “spiky” pulses that follow a log-normal distribution in peak flux density. From 1913 pulses, we detected 53 pulses whose peak flux densities are 10 times greater than that of the integrated profile. They are concentrated in pulse phase at the peaks of the integrated profile. The pulse widths at the 50% level of these bright pulses were between 0.°2 and 0.°9, much narrower than that of the integrated profile (∼12°). The observed pulse widths may be limited by interstellar scattering. No clear correlation was found between the widths and peak flux density of these pulses and no evidence was found for subpulse drifting. Relatively strong spiky pulses are also detected in the other five epochs of observation, showing the same properties as those detected in MJD 56836. These strong spiky pulses cannot be classified as “giant” pulses but are more closely related to normal pulse emission.

  15. Pulsed Gamma-Rays From the Millisecond Pulsar J0030+0451 with the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M. /Stockholm U., OKC /Stockholm U.; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bastieri, Denis; /INFN, Padua /Padua U.; Battelino, M.; /Stockholm U., OKC /Royal Inst. Tech., Stockholm; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, Elliott D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /George Mason U. /Naval Research Lab, Wash., D.C. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /LPCE, Orleans /Montpellier U. /Sonoma State U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /Stockholm U. /ASDC, Frascati /Naval Research Lab, Wash., D.C. /INFN, Trieste /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Montpellier U. /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Trieste /Hiroshima U.; /more authors..

    2011-11-17

    We report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar PSR J0030+0451 with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second millisecond pulsar to be detected in gamma-rays after PSR J0218+4232, observed by the EGRET instrument on the Compton Gamma Ray Observatory. The spin-down power {dot E} = 3.5 x 10{sup 33} ergs s{sup -1} is an order of magnitude lower than the empirical lower bound of previously known gamma-ray pulsars. The emission profile is characterized by two narrow peaks, respectively 0.07 {+-} 0.01 and 0.08 {+-} 0.02 wide, separated by 0.44 {+-} 0.02 in phase. The first gamma-ray peak falls 0.15 {+-} 0.01 after the main radio peak. The pulse shape is similar to that of the 'normal' gamma-ray pulsars. An exponentially cut-off power-law fit of the emission spectrum leads to an integral photon flux above 100 MeV of (6.76 {+-} 1.05 {+-} 1.35) x 10{sup -8} cm{sup -2} s{sup -1} with cut-off energy (1.7 {+-} 0.4 {+-} 0.5) GeV. Based on its parallax distance of (300 {+-} 90) pc, we obtain a gamma-ray efficiency L{sub {gamma}}/{dot E} {approx_equal} 15% for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.

  16. Pulsed Gamma-Rays From PSR J2021 3651 with the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ajello, Marco; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Atwood, William B.; /UC, Santa Cruz; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bastieri, Denis; /INFN, Padua /Padua U.; Battelino, Milan; /Royal Inst. Tech., Stockholm; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, Ronaldo; /INFN, Pisa; Berenji, Bijan; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, Elliott D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bogaert, G.; /Ecole Polytechnique; Borgland, Anders W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Columbia U. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /George Mason U. /Naval Research Lab, Wash., D.C. /IASF, Milan /IASF, Milan /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /LPCE, Orleans /Montpellier U. /Sonoma State U. /Royal Inst. Tech., Stockholm /Stockholm U. /ASI, Rome /NRAO, Charlottesville /Naval Research Lab, Wash., D.C. /INFN, Trieste /Pavia U. /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Manchester U. /Montpellier U. /Bari U. /INFN, Bari; /more authors..

    2011-11-30

    We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 {+-} 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 {+-} 0.004 {+-} 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 {+-} 3 {+-} 11) x 10{sup -8} cm{sup -2} s{sup -1}. The photon spectrum is well-described by an exponentially cut-off power law of the form dF/dE = kE{sup -{Gamma}}e{sup (-E/E{sub c})} where the energy E is expressed in GeV. The photon index is {Gamma} = 1.5 {+-} 0.1 {+-} 0.1 and the exponential cut-off is E{sub c} = 2.4 {+-} 0.3 {+-} 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is < 10% of the pulsed emission at the 95% confidence level. Radio polarization measurements yield a rotation measure of RM = 524 {+-} 4 rad m{sup -2} but a poorly constrained magnetic geometry. Re-analysis of Chandra data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase-aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Gamma-ray emission from the polar cap region seems unlikely for this pulsar.

  17. Pulsar Timing Techniques

    CERN Document Server

    Lommen, Andrea N

    2013-01-01

    We describe the procedure, nuances, issues, and choices involved in creating times-of-arrival (TOAs), residuals and error bars from a set of radio pulsar timing data. We discuss the issue of mis-matched templates, the problem that wide- bandwidth backends introduce, possible solutions to that problem, and correcting for offsets introduced by various observing systems.

  18. Scintillation Velocity of PSR B0329+54

    Indian Academy of Sciences (India)

    R. X. Zhou; N. Wang; Z. Y. Liu; X. Liu

    2011-03-01

    We monitored PSR B0329+54 for one year using the Nanshan 25-m radio telescope, the scintillation velocity VISS shows evidence of systematic variation with the day of the year. States of interstellar medium (ISM) are discussed.

  19. Transformation of a Star into a Planet in a Millisecond Pulsar Binary

    CERN Document Server

    Bailes, M; Bhalerao, V; Bhat, N D R; Burgay, M; Burke-Spolaor, S; D'Amico, N; Johnsto, S; Keith, M J; Kramer, M; Kulkarni, S R; Levin, L; Lyne, A G; Milia, S; Possenti, A; Spitler, L; Stappers, B; van Straten, W

    2011-01-01

    Millisecond pulsars are thought to be neutron stars that have been spun-up by accretion of matter from a binary companion. Although most are in binary systems, some 30% are solitary, and their origin is therefore mysterious. PSR J1719-1438, a 5.7 ms pulsar, was detected in a recent survey with the Parkes 64m radio telescope. We show that it is in a binary system with an orbital period of 2.2 h. Its companion's mass is near that of Jupiter, but its minimum density of 23 g cm$^{-3}$ suggests that it may be an ultra-low mass carbon white dwarf. This system may thus have once been an Ultra Compact Low-Mass X-ray Binary, where the companion narrowly avoided complete destruction.

  20. PSRs J0248+6021 and J2240+5832: Young Pulsars in the Northern Galactic Plane. Discovery, Timing, and Gamma-ray observations

    CERN Document Server

    Theureau, G; Cognard, I; Desvignes, G; Smith, D A; Casandjian, J M; Cheung, C C; Craig, H A; Donato, D; Foster, R; Guillemot, L; Harding, A K; Lestrade, J -F; Ray, P S; Romani, R W; Thompson, D J; Tian, W W; Watters, K

    2010-01-01

    Pulsars PSR J0248+6021 (rotation period P=217 ms and spin-down power Edot = 2.13E35 erg/s) and PSR J2240+5832 (P=140 ms, Edot = 2.12E35 erg/s) were discovered in 1997 with the Nancay radio telescope during a northern Galactic plane survey, using the Navy-Berkeley Pulsar Processor (NBPP) filter bank. GeV gamma-ray pulsations from both were discovered using the Fermi Large Area Telescope. Twelve years of radio and polarization data allow detailed investigations. The two pulsars resemble each other both in radio and in gamma-ray data. Both are rare in having a single gamma-ray pulse offset far from the radio peak. The high dispersion measure for PSR J0248+6021 (DM = 370 pc cm^-3) is most likely due to its being within the dense, giant HII region W5 in the Perseus arm at a distance of 2 kpc, not beyond the edge of the Galaxy as obtained from models of average electron distributions. Its high transverse velocity and the low magnetic field along the line-of-sight favor this small distance. Neither gamma-ray, X-ray,...

  1. Observations of Accreting Pulsars

    Science.gov (United States)

    Bildsten, Lars; Chakrabarty, Deepto; Chiu, John; Finger, Mark H.; Koh, Danny T.; Nelson, Robert W.; Prince, Thomas A.; Rubin, Bradley C.; Scott, D. Matthew; Stollberg, Mark; Vaughan, Brian A.; Wilson, Colleen A.; Wilson, Robert B.

    1997-01-01

    We summarize 5 years of continuous monitoring of accretion-powered pulsars with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory. Our 20-70 keV observations have determined or refined the orbital parameters of 13 binaries, discovered five new transient accreting pulsars, measured the pulsed flux history during outbursts of 12 transients (GRO J1744-28, 4U 0115+634, GRO J1750-27, GS 0834-430, 2S 1417-624, GRO J1948+32, EXO 2030+375, GRO J1008-57, A0535+26, GRO J2058+42, 4U 1145-619, and A1118-616), and also measured the accretion torque history during outbursts of six of those transients whose orbital param- eters were also known. We have also continuously measured the pulsed flux and spin frequency for eiaht persistently accreting pulsars (Her X-1, Cen X-3, Vela X-1, OAO 1657-415, GX 301-2, 4U 1626-67, 4U 1538-52, and GX 1+4). Because of their continuity and uniformity over a long baseline, BATSE observations have provided new insights into the long-term behavior of accreting magnetic neutron stars. We have found that all accreting pulsars show stochastic variations in their spin frequencies and luminosities, including those displaying secular spin-up or spin-down on long timescales, which blurs the con- ventional distinction between disk-fed and wind-fed binaries. Pulsed flux and accretion torque are strongly correlated in outbursts of transient accreting pulsars but are uncorrelated, or even anti- correlated, in persistent sources. We describe daily folded pulse profiles, frequency, and flux measurements that are available through the Compton Observatory Science Support Center at NASA/Goddard Space Flight Center.

  2. Spin-Down Measurement of PSR J1852+0040 in Kesteven 79: Central Compact Objects as Anti-Magnetars

    Science.gov (United States)

    Halpern, J. P.; Gotthelf, E. V.

    2010-01-01

    Using XMM-Newton and Chandra, we achieved phase-connected timing of the 105 ms X-ray pulsar PSR J1852+0040 that provides the first measurement of the spin-down rate of a member of the class of central compact objects (CCOs) in supernova remnants. We measure \\dot{P} = (8.68 ± 0.09) × 10^{-18}, and find no evidence for timing noise or variations in X-ray flux over 4.8 year. In the dipole spin-down formalism, this implies a surface magnetic field strength Bs = 3.1 × 1010 G, the smallest ever measured for a young neutron star, and consistent with being a fossil field. In combination with upper limits on Bs from other CCO pulsars, this is strong evidence in favor of the "anti-magnetar" explanation for their low luminosity and lack of magnetospheric activity or synchrotron nebulae. While this dipole field is small, it can prevent accretion of sufficient fall-back material so that the observed X-ray luminosity of Lx = 5.3 × 1033(d/7.1 kpc)2 erg s-1 must instead be residual cooling. The spin-down luminosity of PSR J1852+0040, \\dot{E} = 3.0 × 10^{32} erg s-1, is an order of magnitude smaller than Lx . Fitting of the X-ray spectrum to two blackbodies finds small emitting radii, R 1 = 1.9 km and R 2 = 0.45 km, for components of kT 1 = 0.30 keV and kT 2 = 0.52 keV, respectively. Such small, hot regions are ubiquitous among CCOs, and are not yet understood in the context of the anti-magnetar picture because anisotropic surface temperature is usually attributed to the effects of strong magnetic fields.

  3. A Search for Very High Energy Gamma Rays from the Missing Link Binary Pulsar J1023+0038 with VERITAS

    Science.gov (United States)

    Aliu, E.; Archambault, S.; Archer, A.; Benbow, W.; Bird, R.; Biteau, J.; Buchovecky, M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dickinson, H. J.; Eisch, J. D.; Falcone, A.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Flinders, A.; Fortin, P.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Griffin, S.; Grube, J.; Gyuk, G.; Hütten, M.; Håkansson, N.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Lang, M. J.; Loo, A.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Moriarty, P.; Mukherjee, R.; Nguyen, T.; Nieto, D.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Pandel, D.; Park, N.; Pelassa, V.; Petrashyk, A.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rulten, C.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Varlotta, A.; Vincent, S.; Wakely, S. P.; Weiner, O. M.; Weinstein, A.; Wilhelm, A.; Williams, D. A.; Zitzer, B.; Chernyakova, M.; Roberts, M. S. E.

    2016-11-01

    The binary millisecond radio pulsar PSR J1023+0038 exhibits many characteristics similar to the gamma-ray binary system PSR B1259-63/LS 2883, making it an ideal candidate for the study of high-energy nonthermal emission. It has been the subject of multiwavelength campaigns following the disappearance of the pulsed radio emission in 2013 June, which revealed the appearance of an accretion disk around the neutron star. We present the results of very high energy (VHE) gamma-ray observations carried out by the Very Energetic Radiation Imaging Telescope Array System before and after this change of state. Searches for steady and pulsed emission of both data sets yield no significant gamma-ray signal above 100 GeV, and upper limits are given for both a steady and pulsed gamma-ray flux. These upper limits are used to constrain the magnetic field strength in the shock region of the PSR J1023+0038 system. Assuming that VHE gamma rays are produced via an inverse Compton mechanism in the shock region, we constrain the shock magnetic field to be greater than ˜2 G before the disappearance of the radio pulsar and greater than ˜10 G afterward.

  4. High energy $\\gamma$-ray emission from PSR B1259$-$63 during 2014 and 2010 periastron passages

    CERN Document Server

    Caliandro, G Andrea; Li, Jian; Torres, Diego F; Wood, Kent

    2015-01-01

    PSR B1259$-$63/SS 2883 is a $\\gamma$-ray binary system composed of a radio pulsar in a long (1236.7 days) and elliptical ($e\\sim0.87$) orbit around a Be star. In its 2010 periastron passage, multiwavelength emission from radio to TeV was observed, and an unexpected GeV flare was detected by the Fermi Large Area Telescope (LAT). Here we present the results of the LAT monitoring of PSR B1259$-$63 during its most recent 2014 periastron passage. We confirm that the GeV flare is recurrent within the orbit. The comparison of the 2014 and 2010 periastron passages shows overall similarities of flare durations, average flux levels, and spectra. In contrast, the detailed time evolutions of the two flares present interesting differences. Indeed, the light curves of the two flares show both a different structure and peak energy flux ($9.6 \\pm1.8 \\times 10^{-10}$ erg cm$^{-2}$ s$^{-1}$ and $7.1 \\pm1.3 \\times 10^{-10}$ erg cm$^{-2}$ s$^{-1}$, respectively in 2010 and 2014). While the tail of the 2010 flare the flux decayed...

  5. On the randomness of pulsar nulls

    Science.gov (United States)

    Redman, Stephen L.; Rankin, Joanna M.

    2009-05-01

    Pulsar nulling is not always a random process; most pulsars, in fact, null non-randomly. The Wald-Wolfowitz statistical runs test is a simple diagnostic that pulsar astronomers can use to identify pulsars that have non-random nulls. It is not clear at this point how the dichotomy in pulsar nulling randomness is related to the underlying nulling phenomenon, but its nature suggests that there are at least two distinct reasons that pulsars null.

  6. The TeV {gamma}-ray binary PSR B1259-63. Observations with the high energy stereoscopic system in the years 2005-2007

    Energy Technology Data Exchange (ETDEWEB)

    Kerschhaggl, Matthias

    2010-04-06

    PSR B1259-63/SS2883 is a binary system where a 48 ms pulsar orbits a massive Be star with a period of 3.4 years. The system exhibits variable, non-thermal radiation around periastron on the highly eccentric orbit (e=0.87) visible from radio to very high energies (VHE; E>100 GeV). When being detected in TeV {gamma}-rays with the High Energy Stereoscopic System (H.E.S.S.) in 2004 it became known as the first variable galactic VHE source. This thesis presents VHE data from PSR B1259-63 as taken during the years 2005, 2006 and before as well as shortly after the 2007 periastron passage. These data extend the knowledge of the lightcurve of this object to all phases of the binary orbit. The lightcurve constrains physical mechanisms present in this TeV source. Observations of VHE {gamma}-rays with the H.E.S.S. telescope array using the Imaging Atmospheric Cherenkov Technique were performed. The H.E.S.S. instrument features an angular resolution of < 0.1 and an energy resolution of < 20%. Gamma-ray events in an energy range of 0.5-70 TeV were recorded. From these data, energy spectra and lightcurve with a monthly time sampling were extracted. VHE {gamma}-ray emission from PSRB1259-63 was detected with an overall significance of 9.5 standard deviations using 55 h of exposure, obtained from April to August 2007. The monthly flux of -rays during the observation period was measured, yielding VHE lightcurve data for the early pre-periastron phase of the system for the first time. No spectral variability was found on timescales of months. The spectrum is described by a power law with a photon index of {gamma}=2.8{+-}0.2{sub stat}{+-}0.2{sub sys} and flux normalisation {phi}{sub 0}=(1.1{+-}0.1{sub stat}{+-}0.2{sub sys}) x 10{sup -12} TeV{sup -1}cm{sup -2}s{sup -1}. PSR B1259-63 was also monitored in 2005 and 2006, far from periastron passage, comprising 8.9 h and 7.5 h of exposure, respectively. No significant excess of {gamma}-rays is seen in those observations. PSR B1259-63 has

  7. Phase-Resolved Spectra of PSR B0525+21 and PSR B2020+28

    Indian Academy of Sciences (India)

    J. L. Chen; H. G. Wang; N. Wang

    2011-03-01

    Using the published data of multi-frequency time-aligned pulse profiles from Kuzmin et al. (1998), we calculate the phase-resolved spectra of PSRs B0525+21 and B2020+28. The results reveal that conaldouble pulsars have common `M’-shaped phase-resolved spectra.

  8. X-ray pulsar rush in 1998

    Energy Technology Data Exchange (ETDEWEB)

    Imanishi, K.; Tsujimoto, K.; Nishiuchi, Mamiko; Yokogawa, J.; Koyama, K. [Kyoto Univ., Faculty of Science, Kyoto (Japan)

    1999-08-01

    We present recent remarkable topics about discoveries of X-ray pulsars. 1. Pulsations from two Soft Gamma-ray Repeaters: These pulsars have enormously strong magnetic field (B {approx} 10{sup 15} G), thus these are called as 'magnetar', new type of X-ray pulsars. 2. New Crab-like pulsars: These discoveries lead to suggesting universality of Crab-like pulsars. 3. An X-ray bursting millisecond pulsar: This is strong evidence for the recycle theory of generating radio millisecond pulsars. 4. X-ray pulsar rush in the SMC: This indicates the younger star formation history in the SMC. (author)

  9. Gamma rays from Galactic pulsars

    OpenAIRE

    2014-01-01

    Gamma rays from young pulsars and milli-second pulsars are expected to contribute to the diffuse gamma-ray emission measured by the {\\it Fermi} Large Area Telescope (LAT) at high latitudes. We derive the contribution of the pulsars undetected counterpart by using information from radio to gamma rays and we show that they explain only a small fraction of the isotropic diffuse gamma-ray background.

  10. Five and a half roads to form a millisecond pulsar

    CERN Document Server

    Tauris, Thomas M

    2011-01-01

    In this review I discuss the characteristics and the formation of all classes of millisecond pulsars (MSPs). The main focus is on the stellar astrophysics of X-ray binaries leading to the production of fully recycled MSPs with white dwarf (WD) or substellar semi-degenerate companions. Depending on the nature of the companion star MSPs are believed to form from either low-mass X-ray binaries (LMXBs) or intermediate-mass X-ray binaries (IMXBs). For each of these two classes of X-ray binaries the evolutionary status of the donor star -- or equivalently, the orbital period -- at the onset of the Roche-lobe overflow (RLO) is the determining factor for the outcome of the mass-transfer phase and thus the nature of the MSP formed. Furthermore, the formation of binary MSPs is discussed in context of the (P,P_dot)-diagram, as well as new interpretations of the Corbet diagram. Finally, I present new models of Case A RLO of IMXBs in order to reproduce the two solar mass pulsar PSR J1614-2230.

  11. Featured Image: A Pulsar Is Obscured by a Solar Explosion

    Science.gov (United States)

    Kohler, Susanna

    2016-12-01

    This series of images (click for the full view!), taken by the Solar and Heliospheric Observatory satellite (SOHO) in August 2015, reveals a tremendous outburst of plasma and magnetic field from the Sun: a coronal mass ejection (CME). If you look closely, youll note that as the CME expands from the Suns surface, it passes in front of a dot highlighted in yellow. This dot marks the location of a distant background pulsar, PSR B0950+08. In a recent study led by Tim Howard (Southwest Research Institute), a team of scientists studied the change observed in the radio emission of this pulsar as the CME passed by in the foreground. The team used these observations to estimate the CMEs density and magnetic field measurements that can tell us more about the nature of the magnetic field in the Suns corona and the solar wind.You can check out the animation of this CME, also taken with SOHOs LASCO instrument, below (the CME starts around 20 seconds in), or you can find out more from the original paper!http://cdn.iopscience.com/images/0004-637X/831/2/208/Full/apjaa35ecf1_video.mp4CitationT. A. Howard et al 2016 ApJ 831 208. doi:10.3847/0004-637X/831/2/208

  12. Interstellar Scintillation od Pulsar B0809+74

    CERN Document Server

    Rickett, B; Markkanen, J; Rickett, Barney; Coles, Bill; Markkanen, Jussi

    1999-01-01

    Weak interstellar scintillations of pulsar B0809+74 were observed at two epochs using a 30m EISCAT antenna at 933 MHz. These have been used to constrain the spectrum, the distribution and the transverse velocity of the scattering plasma with respect to the local standard of rest (LSR). The Kolmogorov power law is a satisfactory model for the electron density spectrum at scales between 20 megameters and 1 gigameter. We compare the observations with model calculations from weak scintillation theory and the known transverse velocities of the pulsar and the Earth. The simplest model is that the scattering is uniformly distributed along the 310 pc line of sight (l=140 deg, b=32 deg) and is stationary in the LSR. With the scattering measure as the only free parameter, this model fits the data within the errors and a range of about +/-10 km/s in velocity is also allowed. The integrated level of turbulence is low, being comparable to that found toward PSR B0950+08, and suggests a region of low local turbulence over a...

  13. A Massive Millisecond Pulsar in an Eccentric Binary

    CERN Document Server

    Barr, E D; Kramer, M; Champion, D J; Berezina, M; Bassa, C G; Lyne, A G; Stappers, B W

    2016-01-01

    The recent discovery of a population of eccentric (e ~ 0.1) millisecond pulsar (MSP) binaries with low-mass white dwarf companions in the Galactic field represents a challenge to evolutionary models that explain MSP formation as recycling: all such models predict that the orbits become highly circularised during a long period of accretion. The members of this new population exhibit remarkably similar properties (orbital periods, eccentricities, companion masses, spin periods) and several models have been put forward that suggest a common formation channel. In this work we present the results of an extensive timing campaign focusing on one member of this new population, PSR J1946+3417. Through measurement of the both the advance of periastron and Shapiro delay for this system, we determine the mass of the pulsar, companion and the inclination of the orbit to be 1.828(22) Msun, 0.2656(19) Msun and 76.4(6) , under the assumption that general relativity is the true description of gravity. Notably, this is the thi...

  14. Precision Astrometry with the Very Long Baseline Array: Parallaxes and Proper Motions for 14 Pulsars

    CERN Document Server

    Chatterjee, S; Vlemmings, W H T; Goss, W M; Lazio, T J W; Cordes, J M; Thorsett, S E; Fomalont, E B; Lyne, A G; Krämer, M

    2009-01-01

    Astrometry can bring powerful constraints to bear on a variety of scientific questions about neutron stars, including their origins, astrophysics, evolution, and environments. Using phase-referenced observations at the VLBA, in conjunction with pulsar gating and in-beam calibration, we have measured the parallaxes and proper motions for 14 pulsars. The smallest measured parallax in our sample is 0.13+-0.02 mas for PSR B1541+09, which has a most probable distance of 7.2+1.3-1.1 kpc. We detail our methods, including initial VLA surveys to select candidates and find in-beam calibrators, VLBA phase-referencing, pulsar gating, calibration, and data reduction. The use of the bootstrap method to estimate astrometric uncertainties in the presence of unmodeled systematic errors is also described. Based on our new model-independent estimates for distance and transverse velocity, we investigate the kinematics and birth sites of the pulsars and revisit models of the Galactic electron density distribution. We find that yo...

  15. Multiwavelength Observations of the Redback Millisecond Pulsar J1048+2339

    CERN Document Server

    Deneva, J S; Camilo, F; Halpern, J P; Wood, K; Cromartie, H T; Ferrara, E; Kerr, M; Ransom, S M; Wolff, M T; Chambers, K C; Magnier, E A

    2016-01-01

    We report on radio timing and multiwavelength observations of the 4.66 ms redback pulsar J1048+2339, which was discovered in an Arecibo search targeting the Fermi-LAT source 3FGLJ1048.6+2338. Two years of timing allowed us to derive precise astrometric and orbital parameters for the pulsar. PSR J1048+2339 is in a 6-hour binary, and exhibits radio eclipses over half the orbital period and rapid orbital period variations. The companion has a minimum mass of 0.3 solar masses, and we have identified a $V \\sim 20$ variable optical counterpart in data from several surveys. The phasing of its $\\sim 1$~mag modulation at the orbital period suggests highly efficient and asymmetric heating by the pulsar wind, which may be due to an intrabinary shock that is distorted near the companion, or to the companion's magnetic field channeling the pulsar wind to specific locations on its surface. We also present gamma-ray spectral analysis of the source and preliminary results from searches for gamma-ray pulsations using the radi...

  16. Where Are the R-modes? Chandra Observations of Millisecond Pulsars

    Science.gov (United States)

    Mahmoodifar, Simin; Strohmayer, Tod E.

    2017-08-01

    We present the results of Chandra observations of two non-accreting millisecond pulsars PSRs J1640+2224 (J1640) and J1709+2313(J1709), with low inferred magnetic fields in order to constrain their surface temperatures, obtain limits on the amplitude of unstable r-modes in them and make comparisons with similar limits obtained for a sample of accreting LMXB neutron stars (NSs). We detect both pulsars in the X-ray band for the first time. We found upper limits on the global surface temperature of these pulsars that are ~ 3.3 - 4.7 × 105 K. These sources are several Gyr old. In all standard cooling models NSs cool to surface temperatures less than 104 K in less than 107 yr. While we derived upper limits on the surface temperatures of these sources, they appear to be consistent with the values measured for PSR J0437-4715 and J2124-3358. Taken together these results suggest that the surface temperatures of at least some MSPs are significantly higher, given their ages, than standard cooling models would suggest. For pulsars that are inside the r-mode instability window, r-mode dissipation can provide a potential source of reheating.

  17. Non-thermal radiation from a pulsar wind interacting with an inhomogeneous stellar wind

    CERN Document Server

    de la Cita, Víctor M; Paredes-Fortuny, Xavier; Khangulyan, Dmitry; Perucho, Manel

    2016-01-01

    Binaries hosting a massive star and a non-accreting pulsar are powerful non-thermal emitters due to the interaction of the pulsar and the stellar wind. The winds of massive stars are thought to be inhomogeneous, which could have an impact on the non-thermal emission. We study numerically the impact of the presence of inhomogeneities or clumps in the stellar wind on the high-energy non-thermal radiation of high-mass binaries hosting a non-accreting pulsar. We compute the trajectories and physical properties of the streamlines in the shocked pulsar wind without clumps, with a small clump, and with a large one. This information is used to compute the synchrotron and inverse Compton emission from the non-thermal populations, accounting also for the effect of gamma-ray absorption through pair creation. A specific study is done for PSR B1259-63/LS2883. When stellar wind clumps perturb the two-wind interaction region, the associated non-thermal radiation in the X-ray band,of synchrotron origin, and in the GeV-TeV ba...