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.

Recent Timing Results for PSR B1259 - 63

Science.gov (United States)

Wex, N.; Johnston, S.

The binary pulsar PSR B1259 - 63 is in a highly eccentric 3.4 yr orbit around the Be star SS 2883. Timing observations of this pulsar, made over a 7 yr period using the Parkes 64 m radio-telescope, cover two periastron passages, in 1990 August and 1994 January. The timing observations of PSR B1259 - 63 clearly show evidence for timing noise which is domina ted by a cubic term. Unfortunately, the large amplitude timing noise and data over only two complete orbits make it difficult to produce a unique timing solution for this pulsar. However, if the long term behavior of timing noise is completely modeled by a cubic term, both dot ω and dot x terms are required in the timing model which could be a result of a precessing orbit caused by the quadrupole moment of the tilted companion star. In this paper we summarise the timing observations for the PSR B1259 - 63 system; full details are given in Wex et al. (1997).

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.

THE X-RAY COUNTERPART OF THE HIGH-B PULSAR PSR J0726-2612

Energy Technology Data Exchange (ETDEWEB)

Speagle, J. S.; Kaplan, D. L. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Van Kerkwijk, M. H., E-mail: kaplan@uwm.edu, E-mail: joshuaspeagle@college.harvard.edu, E-mail: mhvk@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)

2011-12-20

Middle-aged, cooling neutron stars are observed both as relatively rapidly spinning radio pulsars and as more slowly spinning, strongly magnetized isolated neutron stars (INSs), which stand out by their thermal X-ray spectra. The difference between the two classes may be that the INSs initially had much stronger magnetic fields, which decayed. To test this, we used the Chandra X-ray Observatory to observe 1RXS J072559.8-261229, a possible X-ray counterpart to PSR J0726-2612, which, with its 3.44 s period and 3 Multiplication-Sign 10{sup 13} G inferred magnetic field strength, is the nearest and least extincted among the possible slowly spinning, strong-field INS progenitors (it likely is in the Gould Belt, at {approx}1 kpc). We confirm the identification and find that the pulsar has a spectrum consistent with being purely thermal, with blackbody temperature kT = 87 {+-} 5 eV and radius R = 5.7{sup +2.6}{sub -1.3} km at a distance of 1 kpc. We detect sinusoidal pulsations at twice the radio period with a semi-amplitude of 27% {+-} 5%. The properties of PSR J0726-2612 strongly resemble those of the INSs, except for its much shorter characteristic age of 200 kyr (instead of several Myr). We conclude that PSR J0726-2612 is indeed an example of a young INS, one that started with a magnetic field strength on the low end of those inferred for the INSs, and that, therefore, decayed by a relatively small amount. Our results suggest that the long-period, strong-field pulsars and the INSs are members of the same class, and open up new opportunities to understand the puzzling X-ray and optical emission of the INSs through radio observations of PSR J0726-2612.

FERMI LAT PULSED DETECTION OF PSR J0737-3039A IN THE DOUBLE PULSAR SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Guillemot, L.; Kramer, M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Johnson, T. J. [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); Craig, H. A.; Romani, R. W.; Kerr, 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); Venter, C. [Centre for Space Research, North-West University, Potchefstroom Campus, Private Bag X6001, 2520 Potchefstroom (South Africa); Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ferdman, R. D. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, M13 9PL (United Kingdom); Stairs, I. H., E-mail: guillemo@mpifr-bonn.mpg.de [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada)

2013-05-10

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 Degree-Sign , 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.

THE X-RAY COUNTERPART OF THE HIGH-B PULSAR PSR J0726–2612

International Nuclear Information System (INIS)

Speagle, J. S.; Kaplan, D. L.; Van Kerkwijk, M. H.

2011-01-01

Middle-aged, cooling neutron stars are observed both as relatively rapidly spinning radio pulsars and as more slowly spinning, strongly magnetized isolated neutron stars (INSs), which stand out by their thermal X-ray spectra. The difference between the two classes may be that the INSs initially had much stronger magnetic fields, which decayed. To test this, we used the Chandra X-ray Observatory to observe 1RXS J072559.8–261229, a possible X-ray counterpart to PSR J0726–2612, which, with its 3.44 s period and 3 × 10 13 G inferred magnetic field strength, is the nearest and least extincted among the possible slowly spinning, strong-field INS progenitors (it likely is in the Gould Belt, at ∼1 kpc). We confirm the identification and find that the pulsar has a spectrum consistent with being purely thermal, with blackbody temperature kT = 87 ± 5 eV and radius R = 5.7 +2.6 –1.3 km at a distance of 1 kpc. We detect sinusoidal pulsations at twice the radio period with a semi-amplitude of 27% ± 5%. The properties of PSR J0726–2612 strongly resemble those of the INSs, except for its much shorter characteristic age of 200 kyr (instead of several Myr). We conclude that PSR J0726–2612 is indeed an example of a young INS, one that started with a magnetic field strength on the low end of those inferred for the INSs, and that, therefore, decayed by a relatively small amount. Our results suggest that the long-period, strong-field pulsars and the INSs are members of the same class, and open up new opportunities to understand the puzzling X-ray and optical emission of the INSs through radio observations of PSR J0726–2612.

Optical observations of the millisecond pulsars PSR 1937+214 and PSR 1953+29

International Nuclear Information System (INIS)

Loredo, T.J.; Ricker, G.R.; Rappaport, S.A.; Middleditch, J.

1984-01-01

The results of photometric and time-resolved optical observations of the fields of the recently discovered ultra-fast radio pulsars, PSR 1937+214 and PSR 1953+29 (Backer et al. 1982; Boriakoff et al. 1983) are reported. Deep images of the fields reveal no conspicuous optical counterpart for PSR 1937+214, though a star with m/sub r/ approx. 20.5 is coincident with the position of PSR 1953+29. Time-resolved images of the fields of both objects, obtained with a new stroboscopic technique, have yielded upper limits on the pulsed near-infrared emission from each object. Constraints on the physical models for these systems derived from the optical studies are briefly discussed. 25 references, 9 figures, 4 tables

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

International Nuclear Information System (INIS)

Li, Miao; Halpern, Jules P.; Thorstensen, John R.

2014-01-01

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 c < 0.30 M ☉ , and the effective temperature to 3560 < T 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.

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.

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.

Discovery of remarkable subpulse drifting pattern in PSR B0818-41

Science.gov (United States)

Bhattacharyya, B.; Gupta, Y.; Gil, J.; Sendyk, M.

The study of pulsars showing systematic subpulse drift patterns provides important clues for understanding of pulsar emission mechanism. Pulsars with wide profiles provide extra insights because of the presence of multiple drift bands (e.g PSR B0826-34). We report the discovery of a remarkable subpulse drift pattern in a relatively less studied wide profile pulsar, PSR B0818-41, using the GMRT. We find simultaneous occurrence of three drift regions with two drift rates, an inner region with steeper apparent drift rate flanked on each side by a region of slower apparent drift rate. Furthermore, the two closely spaced drift regions always maintain a constant phase relationship. These unique drift properties seen for this pulsar is very rare. We interpret that the observed drift pattern is created by intersection of our line of sight (LOS) with two conal rings in a inner LOS (negative beta) geometry. We argue that the carousel rotation periodicity (P_4) and the number of sparks (N_sp) are the same for the rings and claim that P_4 is close to the measured P_3. Based on our analysis results and interpretations, we simulate the radiation from B0818-41. The simulations support our interpretations and reproduce the average profile and the observed drift pattern. The results of our study show that PSR B0818-41 is a powerful system to explore the pulsar radio emission mechanism, the implications of which are also discussed in our work.

The Spin-down of PSR B1509-58

Science.gov (United States)

Gvaramadze, V. V.

It is generally accepted that the PSR B1509-58 is associated with the supernova remnant (SNR) MSH 15-52 . The spin-down age of the pulsar is years, while the size and the general appearance of the SNR suggest that this system is much older. A few possible explanations of this discrepancy have been put forward. We offer an alternative one and suggest that the high spin-down rate of the pulsar characterizes only a relatively short period of its (present) spin history, and that the enhanced braking torque is connected with the interaction between the pulsar's magnetosphere and the dense matter of a circumstellar clump (created during the late evolutionary stages of the supernova (SN) progenitor star). Our suggestion implies that the "true" age of PSR B1509-58 could be much larger than the spin-down age, and therefore the SNR MSH 15-52 is a middle-aged remnant similar to the Vela SNR. Some possible consequences of our suggestion are discussed.

High-energy Emissions from the Pulsar/Be Binary System PSR J2032+4127/MT91 213

Energy Technology Data Exchange (ETDEWEB)

Takata, J. [School of physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Tam, P. H. T. [Institute of Astronomy and Space Science, Sun Yat-Sen University, Guangzhou 510275 (China); Ng, C. W.; Cheng, K. S. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Li, K. L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-2320 (United States); Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Hui, C. Y., E-mail: takata@hust.edu.cn [Department of Astronomy and Space Science, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2017-02-20

PSR J2032+4127 is a radio-loud gamma-ray-emitting pulsar; it is orbiting around a high-mass Be type star with a very long orbital period of 25–50 years, and is approaching periastron, which will occur in late 2017/early 2018. This system comprises a young pulsar and a Be type star, which is similar to the so-called gamma-ray binary PSR B1259–63/LS2883. It is expected therefore that PSR J2032+4127 shows an enhancement of high-energy emission caused by the interaction between the pulsar wind and Be wind/disk around periastron. Ho et al. recently reported a rapid increase in the X-ray flux from this system. In this paper, we also confirm a rapid increase in the X-ray flux along the orbit, while the GeV flux shows no significant change. We discuss the high-energy emissions from the shock caused by the pulsar wind and stellar wind interaction and examine the properties of the pulsar wind in this binary system. We argue that the rate of increase of the X-ray flux observed by Swift indicates (1) a variation of the momentum ratio of the two-wind interaction region along the orbit, or (2) an evolution of the magnetization parameter of the pulsar wind with the radial distance from the pulsar. We also discuss the pulsar wind/Be disk interaction at the periastron passage, and propose the possibility of formation of an accretion disk around the pulsar. We model high-energy emissions through the inverse-Compton scattering process of the cold-relativistic pulsar wind off soft photons from the accretion disk.

RELATIVISTIC MEASUREMENTS FROM TIMING THE BINARY PULSAR PSR B1913+16

Energy Technology Data Exchange (ETDEWEB)

Weisberg, J. M.; Huang, Y., E-mail: jweisber@carleton.edu [Department of Physics and Astronomy, Carleton College, Northfield, MN 55057 (United States)

2016-09-20

We present relativistic analyses of 9257 measurements of times-of-arrival from the first binary pulsar, PSR B1913+16, acquired over the last 35 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 ± 0.001 M {sub ☉} and 1.390 ± 0.001 M {sub ☉}, respectively. In addition, the complete system characterization allows for the creation of relativistic gravitation test by comparing measured and predicted sizes of various relativistic phenomena. We find that the ratio of the observed orbital period decrease caused by gravitational wave damping (corrected by a kinematic term) to the general relativistic prediction is 0.9983 ± 0.0016, thereby confirms the existence and strength of gravitational radiation as predicted by general relativity. For the first time in this system, we have also successfully measured the two parameters characterizing the Shapiro gravitational propagation delay, and found that their values are consistent with general relativistic predictions. For the first time in any system, we have also measured the relativistic shape correction to the elliptical orbit, δ {sub θ} , although its intrinsic value is obscured by currently unquantified pulsar emission beam aberration. We have also marginally measured the time derivative of the projected semimajor axis, which, when improved in combination with beam aberration modeling from geodetic precession observations, should ultimately constrain the pulsar’s moment of inertia.

Soft X-ray emission from the radio pulsar PSR 0656 + 14

Science.gov (United States)

Cordova, F. A.; Middleditch, J.; Hjellming, R. M.; Mason, K. O.

1989-01-01

A radio source with a flux density of a few mJy was found in the error region of the soft X-ray source E0656 + 14, and identified as the radio pulsar PSR 0656 + 14. The radio source has a steep, nonthermal spectrum and a high degree of linear (62 percent) and circular (19 percent) polarization. The X-ray spectrum of the pulsar is among the softest sources observed with the Einstein Observatory. The X-ray data taken with the Einstein imaging proportional counter (IPC) permit a range of blackbody temperatures of 3-6 x 10 to the 5th K, and an equivalent column density of hydrogen smaller than 4 x 10 to the 20th/sq cm. If the assumption is made that the X-ray flux is thermal radiation from surface of the neutron star, then the pulsar must be at a distance smaller than 550 pc, consistent with the low dispersion measure of PSR 0656 + 14. The X-ray timing data suggest that the X-ray emission is modulated at the pulsar's 0.385-s spin period with an amplitude of 18 percent + or - 6 percent, and that there is a 0.0002 probability that this is spurious. It was noted that PSR 0656 + 14 is close to the geometric center of a 20-deg diameter soft X-ray emitting ring called the Gemini-Monoceros enhancement. The close distance of the pulsar, together with its relatively young age of 1.1 x 10 to the 5th yr, makes it possible that the ring is a supernova remnant from the explosion of the pulsar's progenitor. A radio source extending over a region 1.2 to 3.3 arcmin south of the pulsar is a candidate for association with the pulsar.

Soft X-ray emission from the radio pulsar PSR 0656 + 14

International Nuclear Information System (INIS)

Cordova, F.A.; Middleditch, J.; Hjellming, R.M.; Mason, K.O.

1989-01-01

A radio source with a flux density of a few mJy was found in the error region of the soft X-ray source E0656 + 14, and identified as the radio pulsar PSR 0656 + 14. The radio source has a steep, nonthermal spectrum and a high degree of linear (62%) and circular (19%) polarization. The X-ray spectrum of the pulsar is among the softest sources observed with the Einstein Observatory. The X-ray data taken with the Einstein imaging proportional counter (IPC) permit a range of blackbody temperatures of 3-6 x 10 to the 5th K, and an equivalent column density of hydrogen smaller than 4 x 10 to the 20th/sq cm. If the assumption is made that the X-ray flux is thermal radiation from surface of the neutron star, then the pulsar must be at a distance smaller than 550 pc, consistent with the low dispersion measure of PSR 0656 + 14. The X-ray timing data suggest that the X-ray emission is modulated at the pulsar's 0.385-s spin period with an amplitude of 18% + or - 6%, and that there is a 0.0002 probability that this is spurious. It was noted that PSR 0656 + 14 is close to the geometric center of a 20-deg diameter soft X-ray emitting ring called the Gemini-Monoceros enhancement. The close distance of the pulsar, together with its relatively young age of 1.1 x 10 to the 5th yr, makes it possible that the ring is a supernova remnant from the explosion of the pulsar's progenitor. A radio source extending over a region 1.2 to 3.3 arcmin south of the pulsar is a candidate for association with the pulsar. 46 refs

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.

The High Time Resolution Universe Pulsar Survey - XIII. PSR J1757-1854, the most accelerated binary pulsar

Science.gov (United States)

Cameron, A. D.; Champion, D. J.; Kramer, M.; Bailes, M.; Barr, E. D.; Bassa, C. G.; Bhandari, S.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; Eatough, R. P.; Flynn, C. M. L.; Freire, P. C. C.; Jameson, A.; Johnston, S.; Karuppusamy, R.; Keith, M. J.; Levin, L.; Lorimer, D. R.; Lyne, A. G.; McLaughlin, M. A.; Ng, C.; Petroff, E.; Possenti, A.; Ridolfi, A.; Stappers, B. W.; van Straten, W.; Tauris, T. M.; Tiburzi, C.; Wex, N.

2018-03-01

We report the discovery of PSR J1757-1854, a 21.5-ms pulsar in a highly-eccentric, 4.4-h orbit with a neutron star (NS) companion. PSR J1757-1854 exhibits some of the most extreme relativistic parameters of any known pulsar, including the strongest relativistic effects due to gravitational-wave damping, with a merger time of 76 Myr. Following a 1.6-yr timing campaign, we have measured five post-Keplerian parameters, yielding the two component masses (mp = 1.3384(9) M⊙ and mc = 1.3946(9) M⊙) plus three tests of general relativity, which the theory passes. The larger mass of the NS companion provides important clues regarding the binary formation of PSR J1757-1854. With simulations suggesting 3-σ measurements of both the contribution of Lense-Thirring precession to the rate of change of the semimajor axis and the relativistic deformation of the orbit within ˜7-9 yr, PSR J1757-1854 stands out as a unique laboratory for new tests of gravitational theories.

PSR J1755-2550: a young radio pulsar with a massive, compact companion

Science.gov (United States)

Ng, C.; Kruckow, M. U.; Tauris, T. M.; Lyne, A. G.; Freire, P. C. C.; Ridolfi, A.; Caiazzo, I.; Heyl, J.; Kramer, M.; Cameron, A. D.; Champion, D. J.; Stappers, B.

2018-06-01

Radio pulsars found in binary systems with short orbital periods are usually fast spinning as a consequence of recycling via mass transfer from their companion stars; this process is also thought to decrease the magnetic field of the neutron star being recycled. Here, we report on timing observations of the recently discovered binary PSR J1755-2550 and find that this pulsar is an exception: with a characteristic age of 2.1 Myr, it is relatively young; furthermore, with a spin period of 315 ms and a surface magnetic field strength at its poles of 0.88 × 1012 G, the pulsar shows no sign of having been recycled. Based on its timing and orbital characteristics, the pulsar either has a massive white dwarf (WD) or a neutron star (NS) companion. To distinguish between these two cases, we searched radio observations for a potential recycled pulsar companion and analysed archival optical data for a potential WD companion. Neither work returned conclusive detections. We apply population synthesis modelling and find that both solutions are roughly equally probable. Our population synthesis also predicts a minimum mass of 0.90 M⊙ for the companion star to PSR J1755-2550 and we simulate the systemic runaway velocities for the resulting WDNS systems which may merge and possibly produce Ca-rich supernovae. Whether PSR J1755-2550 hosts a WD or a NS companion star, it is certainly a member of a rare subpopulation of binary radio pulsars.

LONG-TERM X-RAY MONITORING OF THE YOUNG PULSAR PSR B1509–58

International Nuclear Information System (INIS)

Livingstone, Margaret A.; Kaspi, Victoria M.

2011-01-01

It has long been thought that the pulsed X-ray properties of rotation-powered pulsars are stable on long timescales. However, long-term, systematic studies of individual sources have been lacking. Furthermore, dramatic X-ray variability has now been observed from two pulsars having inferred sub-critical dipole magnetic fields. Here we present an analysis of the long-term pulsed X-ray properties of the young, energetic pulsar PSR B1509–58 using data from the Rossi X-ray Timing Explorer. We measured the 2-50 keV pulsed flux for 14.7 yr of X-ray observations and found that it is consistent with being constant on all relevant timescales, and place a 3σ upper limit on day-to-week variability of <28%. In addition, we searched for magnetar-like X-ray bursts in all observations and found none, which we use to constrain the measurable burst rate to less than one per 750 ks of observations. We also searched for variability in the pulse profile and found that it is consistent with being stable on timescales of days to decades. This supports the hypothesis that X-ray properties of rotation-powered X-ray pulsars can be stable on decade-long timescales. In addition, we extend the existing timing solution by 7.1 yr to a total of 28.4 yr and report updated values of the braking index, n = 2.832 ± 0.003, and the second braking index, m = 17.6 ± 1.9.

A glitch in the Crab pulsar (PSR B0531+21)

Science.gov (United States)

Shaw, Benjamin; Lyne, Andrew; Bassa, Cees; Breton, Rene; Jordan, Christine; Keith, Michael; Mickaliger, Mitchell B.; Stappers, Benjamin; Weltevrede, Patrick

2018-05-01

We have detected a glitch in the Crab pulsar, B0531+21, on 2018-04-29. The Crab pulsar is regularly monitored with the 42-ft and Lovell telescopes at the Jodrell Bank Observatory as part of the pulsar timing programme.

On the age of PSR B1509-58

OpenAIRE

Gvaramadze, V. V.

2001-01-01

It is generally accepted that the PSR B1509-58 is associated with the supernova remnant (SNR) MSH 15-52 (G 320.4-01.2). The spin-down age of the pulsar is \\simeq 1700 years, while the size and the general appearance of the SNR suggest that this system is much older. A few possible explanations of this discrepancy have been put forward. We offer an alternative one and suggest that the high spin-down rate of the pulsar characterizes only a relatively short period of its (present) spin history, ...

X-Rays from the Nearby Solitary Millisecond Pulsar PSR J0030+0451 - the Final ROSAT Observations

CERN Document Server

Becker, W; Bäcker, A N; Lommen, D; Becker, Werner; Tr"umper, Joachim; Backer, Andrea N.Lommen & Donald C.

2000-01-01

We report on X-ray observations of the solitary 4.8 ms pulsar PSR J0030+0451. The pulsar was one of the last targets observed in DEC-98 by the ROSAT PSPC. X-ray pulses are detected on a $4.5\\sigma$ level and make the source the $11^{th}$ millisecond pulsar detected in the X-ray domain. The pulsed fraction is found to be $69\\pm18%$. The X-ray pulse profile is characterized by two narrow peaks which match the gross pulse profile observed at 1.4 GHz. Assuming a Crab-like spectrum the X-ray flux is in the range $f_x= 2-3\\times 10^{-13}$ erg s$^{-1}$ cm$^{-2} $ ($0.1-2.4$ keV), implying an X-ray efficiency of $L_x/\\dot{E}\\sim 0.5-5 \\times 10^{-3} (d/0.23 {kpc})^2$.

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.

The Highly Relativistic Binary Pulsar PSR J0737-3039A: Discovery and Implications

OpenAIRE

Burgay, M.; D'Amico, N.; Possenti, A.; Manchester, R. N.; Lyne, A. G.; Joshi, B. C.; McLaughlin, M. A.; Kramer, M.; Sarkissian, J. M.; Camilo, F.; Kalogera, V.; Kim, C.; Lorimer, D. R.

2004-01-01

PSR J0737-3039A is a millisecond pulsar with a spin period of 22.7 ms included in a double-neutron star system with an orbital period of 2.4 hrs. Its companion has also been detected as a radio pulsar, making this binary the first known double-pulsar system. Its discovery has important implications for relativistic gravity tests, gravitational wave detection and plasma physics. Here we will shortly describe the discovery of the first pulsar in this unique system and present the first results ...

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...... curve is complex; there is no detectable unpulsed emission; the energy spectrum is hat, with no evidence of a sharp high-energy cutoff up to greater than 4 GeV. Comparisons of the gamma-ray data with observations at longer wavelengths show that no two of the known gamma-ray pulsars have quite the same...

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.

The End of Accretion: The X-Ray Binary/Millisecond Pulsar Transition Object PSR J1023+0038

Science.gov (United States)

Archibald, Anne

2015-04-01

Millisecond radio pulsars (MSRPs), those spinning hundreds of times per second, have long been understood to be old pulsars that have been spun up by the accretion of matter from a companion in a low-mass X-ray binary (LMXB) phase. Yet the details of this transformation, particularly the end of the accretion process and the birth of a radio pulsar, remain mysterious. I will describe the discovery and detailed study of the first object known to transition between MSRP and LMXB states, PSR J1023+0038. By dint of a multiwavelength campaign of observations in the RMSP state, we are able to measure all the key system parameters and show the existence of an X-ray shock close to the pulsar-facing side of the companion. Since the discovery of PSR J1023+0038, two more objects (XSS J12270-4859 and M28I) have been found to make the same transition, and the study of these transitioning objects has become an active field of research. Most interestingly, PSR J1023+0038 has transitioned back into an LMXB state, with an active accretion disk and a puzzling increase in gamma-ray flux. Our detailed picture of the system allows us to test models of accretion against the phenomena we observe in PSR J1023+0038, and in fact these observations challenge current models: in spite of the low luminosity of the system (and low inferred accretion rate) some material is penetrating the centrifugal barrier and falling on the neutron-star surface. Key evidence for explaining this puzzling behaviour will come when PSR J1023+0038 returns to an MSRP state and we are able to compare pulsar timing models from after the LMXB state with those we obtained in this work.

The spin histories of PSR1821-24 in M28 and PSR1951+32 in CTB80

International Nuclear Information System (INIS)

White, N.E.; Stella, L.

1988-01-01

The spin histories of the 3.05-ms pulsar PSR 1821-24 in the globular cluster M28 and the pulsar PSR 1951 + 32 in the supernova remnant C + B80, show that the equation for the minimum possible period for the spin-up by accretion of an accreting magnetized neutron star is not correct. Also the equation should not be considered a 'hard' barrier when considering the magnetic field-period distribution of recycled radio pulsars. The rapid rotation period and period derivative of both pulsars are consistent with both having undergone a previous interval of accretion. (U.K.)

A CANDIDATE OPTICAL COUNTERPART TO THE MIDDLE AGED γ -RAY PULSAR PSR J1741–2054

Energy Technology Data Exchange (ETDEWEB)

Mignani, R. P.; Marelli, M.; Luca, A. De; Salvetti, D.; Belfiore, A. [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133, Milano (Italy); Testa, V. [INAF—Osservatorio Astronomico di Roma, via Frascati 33, I-00040, Monteporzio (Italy); Pierbattista, M. [Department of Astrophysics and Theory of Gravity, Maria Curie-Sklodowska University, ul. Radziszewskiego 10, 20-031 Lublin (Poland); Razzano, M. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Shearer, A.; Moran, P. [Centre for Astronomy, National University of Ireland, Newcastle Road, Galway (Ireland)

2016-07-10

We carried out deep optical observations of the middle aged γ -ray pulsar PSR J1741−2054 with the Very Large Telescope (VLT). We identified two objects, of magnitudes m {sub v} = 23.10 ± 0.05 and m {sub v} = 25.32 ± 0.08, 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 ∼0.″9 (at the 3 σ 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 ∼28.1 mag arcsec{sup −2}. Future observations are needed to confirm the optical identification of PSR J1741−2054 and characterize the spectrum of its counterpart.

SPECTROSCOPY OF THE INNER COMPANION OF THE PULSAR PSR J0337+1715

International Nuclear Information System (INIS)

Kaplan, David L.; Van Kerkwijk, Marten H.; Koester, Detlev; Stairs, Ingrid H.; Ransom, Scott M.; Archibald, Anne M.; Hessels, Jason W. T.; Boyles, Jason

2014-01-01

The hierarchical triple system PSR J0337+1715 offers an unprecedented laboratory to study secular evolution of interacting systems and to explore the complicated mass-transfer history that forms millisecond pulsars and helium-core white dwarfs. The latter in particular, however, requires knowledge of the properties of the individual components of the system. Here we present precise optical spectroscopy of the inner companion in the PSR J0337+1715 system. We confirm it as a hot, low-gravity DA white dwarf with T eff = 15, 800 ± 100 K and log 10 (g) = 5.82 ± 0.05. We also measure an inner mass ratio of 0.1364 ± 0.0015, entirely consistent with that inferred from pulsar timing, and a systemic radial velocity of 29.7 ± 0.3 km s –1 . Combined with the mass (0.19751 M ☉ ) determined from pulsar timing, our measurement of the surface gravity implies a radius of 0.091 ± 0.005 R ☉ ; combined further with the effective temperature and extinction, the photometry implies a distance of 1300 ± 80 pc. The high temperature of the companion is somewhat puzzling: with current models, it likely requires a recent period of unstable hydrogen burning, and suggests a surprisingly short lifetime for objects at this phase in their evolution. We discuss the implications of these measurements in the context of understanding the PSR J0337+1715 system, as well as of low-mass white dwarfs in general

On The Origin Of Hyper-Fast Pulsars

Science.gov (United States)

Gvaramadze, V. V.

2006-08-01

Recent proper motion and parallax measurements for the pulsar PSR B1508+55 gave the highest (transverse) velocity (~1100 km/s) ever measured for a neutron star (Chatterjee et al. 2005). The spin-down characteristics of PSR B1508+55 (typical of non-recycled pulsars) imply that the high velocity of this pulsar cannot be solely due to disruption of a tight massive binary system. A possible way to account for the high velocity of PSR B1508+55 is to assume that at least a part of this velocity is due to a natal or post-natal kick (Chatterjee et al. 2005). We propose an alternative explanation for the origin of hyper-fast pulsars. We suggest that PSR B1508+55 could be the remnant of a (symmetric) supernova explosion of the helium core of a massive star expelled at high velocity from the dense core of a young massive stellar cluster by an intermediate-mass (binary) black hole. The maximum peculiar velocity of the helium core is limited by the parabolic velocity on its surface and could be as large as ~2000 km/s. Thus, one can account not only for the high velocity measured for PSR B1508+55, but also for the even higher velocity of ~1600 km/s inferred for the pulsar PSR B2224+65 (Guitar; Chatterjee & Cordes 2004) on the basis of its proper motion and the dispersion measure distance estimate.

FERMI LARGE AREA TELESCOPE OBSERVATIONS OF GAMMA-RAY PULSARS PSR J1057-5226, J1709-4429, AND J1952+3252

International Nuclear Information System (INIS)

Abdo, A. A.; Ajello, M.; Bechtol, K.; Berenji, B.; Borgland, A. W.; Bouvier, A.; Buehler, R.; Antolini, E.; Bonamente, E.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Brigida, M.; Bruel, P.; Burnett, T. H.

2010-01-01

The Fermi Large Area Telescope (LAT) data have confirmed the pulsed emission from all six high-confidence gamma-ray pulsars previously known from the EGRET observations. We report results obtained from the analysis of 13 months of LAT data for three of these pulsars (PSR J1057-5226, PSR J1709-4429, and PSR J1952+3252) each of which had some unique feature among the EGRET pulsars. The excellent sensitivity of LAT allows more detailed analysis of the evolution of the pulse profile with energy and also of the variation of the spectral shape with phase. We measure the cutoff energy of the pulsed emission from these pulsars for the first time and provide a more complete picture of the emission mechanism. The results confirm some, but not all, of the features seen in the EGRET data.

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.

Pulsar wind model for the spin-down behavior of intermittent pulsars

Energy Technology Data Exchange (ETDEWEB)

Li, L.; Tong, H.; Yan, W. M.; Yuan, J. P.; Wang, N. [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011 (China); Xu, R. X., E-mail: tonghao@xao.ac.cn [School of Physics, Peking University, Beijing (China)

2014-06-10

Intermittent pulsars are part-time radio pulsars. They have higher slow down rates in the on state (radio-loud) than in the off state (radio-quiet). This gives evidence that particle wind may play an important role in pulsar spindown. The effect of particle acceleration is included in modeling the rotational energy loss rate of the neutron star. Applying the pulsar wind model to the three intermittent pulsars (PSR B1931+24, PSR J1841–0500, and PSR J1832+0029) allows their magnetic fields and inclination angles to be calculated simultaneously. The theoretical braking indices of intermittent pulsars are also given. In the pulsar wind model, the density of the particle wind can always be the Goldreich-Julian density. This may ensure that different on states of intermittent pulsars are stable. The duty cycle of particle wind can be determined from timing observations. It is consistent with the duty cycle of the on state. Inclination angle and braking index observations of intermittent pulsars may help to test different models of particle acceleration. At present, the inverse Compton scattering induced space charge limited flow with field saturation model can be ruled out.

Observing and Modeling the Gamma-Ray Emission from Pulsar/Pulsar Wind Nebula Complex PSR J0205+6449/3C 58

Science.gov (United States)

Li, Jian; Torres, Diego F.; Lin, Ting Ting; Grondin, Marie-Helene; Kerr, Matthew; Lemoine-Goumard, Marianne; de Oña Wilhelmi, Emma

2018-05-01

We present the results of the analysis of eight years of Fermi-LAT data of the pulsar/pulsar wind nebula complex PSR J0205+6449/3C 58. Using a contemporaneous ephemeris, we carried out a detailed analysis of PSR J0205+6449 both during its off-peak and on-peak phase intervals. 3C 58 is significantly detected during the off-peak phase interval. We show that the spectral energy distribution at high energies is the same disregarding the phases considered, and thus that this part of the spectrum is most likely dominated by the nebula radiation. We present results of theoretical models of the nebula and the magnetospheric emission that confirm this interpretation. Possible high-energy flares from 3C 58 were searched for, but none were unambiguously identified.

The Association of PSR B1757-24 and the SNR G5.4-1.2

Science.gov (United States)

Gvaramadze, V. V.

The association of PSR B1757-24 and the supernova remnant (SNR) G5.4-1.2 was recently questioned by Thorsett et al. (2002) on the basis of proper motion measurements of the pulsar and the "incorrect" orientation of the vector of pulsar transverse velocity (inferred from the orientation of the cometary-shaped pulsar wind nebula). We show, however, that the association could be real if both objects are the remnants of an off-centered cavity supernova explosion.

Mechanism of the X-ray and Soft Gamma-ray Emissions from the High Magnetic Field Pulsar: PSR B1509-58

Directory of Open Access Journals (Sweden)

Yu Wang

2013-06-01

Full Text Available We use the outer gap model to explain the spectrum and the energy dependent light curves of the X-ray and soft γ-ray radiations of the spin-down powered pulsar PSR B1509-58. In the outer gap model, most pairs inside the gap are created around the null charge surface and the gap’s electric field separates the opposite charges to move in opposite directions. Consequently, the region from the null charge surface to the light cylinder is dominated by the outflow current and that from the null charge surface to the star is dominated by the inflow current. We suggest that the viewing angle of PSR B1509-58 only receives the inflow radiation. The incoming curvature photons are converted to pairs by the strong magnetic field of the star. The X-rays and soft γ-rays of PSR B1509-58 result from the synchrotron radiation of these pairs. The magnetic pair creation requires a large pitch angle, which makes the pulse profile of the synchrotron radiation distinct from that of the curvature radiation. We carefully trace the pulse profiles of the synchrotron radiation with different pitch angles. We find that the differences between the light curves of different energy bands are due to the different pitch angles of the secondary pairs, and the second peak appearing at E > 10 MeV comes from the region near the star, where the stronger magnetic field allows the pair creation to happen with a smaller pitch angle.

On the origin of the system PSR B 1757-24/SNR G 5.4-1.2

Science.gov (United States)

Gvaramadze, V. V.

2004-03-01

A scenario for the origin of the system PSR B 1757-24/supernova remnant (SNR) G 5.4-1.2 is proposed. It is suggested that both objects are the remnants of a supernova (SN) that exploded within a pre-existing bubble blown-up by a runaway massive star (the SN progenitor) during the final (Wolf-Rayet) phase of its evolution. This suggestion implies that (a) the SN blast centre was significantly offset from the geometric centre of the wind-blown bubble (i.e. from the centre of the future SNR), (b) the bubble was surrounded by a massive wind-driven shell, and (c) the SN blast wave was drastically decelerated by the interaction with the shell. Therefore, one can understand how the relatively young and low-velocity pulsar PSR B 1757-24 was able to escape from the associated SNR G 5.4-1.2 and why the inferred vector of pulsar transverse velocity does not point away from the geometric centre of the SNR. A possible origin of the radio source G 5.27-0.9 (located between PSR B 1757-24 and the SNR G 5.4-1.2) is proposed. It is suggested that G 5.27-0.9 is a lobe of a low Mach number (≃1.7) jet of gas outflowing from the interior of G 5.4-1.2 through the hole bored in the SNR's shell by the escaping pulsar. It is also suggested that the non-thermal emission of the comet-shaped pulsar wind nebula originates in the vicinity of the termination shock and in the cylindric region of subsonically moving shocked pulsar wind. The role of magnetized wind-driven shells (swept-up during the Wolf-Rayet phase from the ambient interstellar medium with the regular magnetic field) in formation of elongated axisymmetric SNRs is discussed.

Giant pulses of pulsar radio emission

OpenAIRE

Kuzmin, A. D.

2007-01-01

Review report of giant pulses of pulsar radio emission, based on our detections of four new pulsars with giant pulses, and the comparative analysis of the previously known pulsars with giant pulses, including the Crab pulsar and millisecond pulsar PSR B1937+21.

Prospects of Constraining the Dense Matter Equation of State from Timing Analysis of Pulsars in Double Neutron Star Binaries: The Cases of PSR J0737 ‒ 3039A and PSR J1757 ‒ 1854

Directory of Open Access Journals (Sweden)

Manjari Bagchi

2018-02-01

Full Text Available The Lense-Thirring effect from spinning neutron stars in double neutron star binaries contributes to the periastron advance of the orbit. This extra term involves the moment of inertia of the neutron stars. The moment of inertia, on the other hand, depends on the mass and spin of the neutron star, as well as the equation of state of the matter. If at least one member of the double neutron star binary (better the faster one is a radio pulsar, then accurate timing analysis might lead to the estimation of the contribution of the Lense-Thirring effect to the periastron advance, which will lead to the measurement of the moment of inertia of the pulsar. The combination of the knowledge on the values of the moment of inertia, the mass and the spin of the pulsar will give a new constraint on the equation of state. Pulsars in double neutron star binaries are the best for this purpose as short orbits and moderately high eccentricities make the Lense-Thirring effect substantial, whereas tidal effects are negligible (unlike pulsars with main sequence or white-dwarf binaries. The most promising pulsars are PSR J0737 − 3039A and PSR J1757 − 1854. The spin-precession of pulsars due to the misalignment between the spin and the orbital angular momentum vectors affect the contribution of the Lense-Thirring effect to the periastron advance. This effect has been explored for both PSR J0737 − 3039A and PSR J1757 − 1854, and as the misalignment angles for both of these pulsars are small, the variation in the Lense-Thirring term is not much. However, to extract the Lense-Thirring effect from the observed rate of the periastron advance, more accurate timing solutions including precise proper motion and distance measurements are essential.

Chandra Images Provide New Vision of Cosmic Explosions

Science.gov (United States)

1999-09-01

Images from NASA's Chandra X-ray Observatory released today reveal previously unobserved features in the remnants of three different supernova explosions. Two of the remnants G21.5-0.9 and PSR 0540-69 show dramatic details of the prodigious production of energetic particles by a rapidly rotating, highly magnetized neutron star, as well as the enormous shell structures produced by the explosions. The image of the third remnant, E0102-72, reveals puzzling spoke-like structures in its interior. G21.5-0.9, in the constellation of Scutum, is about 16,000 light years (1 light year = 6 trillion miles) from Earth. Chandra's image shows a bright nebula surrounded by a much larger diffuse cloud. Inside the inner nebula is a bright central source that is thought to be a rapidly rotating highly magnetized neutron star. A rotating neutron star acts like a powerful generator, creating intense electric voltages that accelerate electrons to speeds close to the speed of light. The total output of this generator is greater than a thousand suns. The fluffy appearance of the central nebula is thought to be due to magnetic field lines which constrain the motions of the high-energy electrons. "It's a remarkable image," said Dr. Patrick Slane of the Harvard-Smithsonian Center for Astrophysics. "Neither the inner core nor the outer shell has ever been seen before." "It is as though we have a set of Russian dolls, with structures embedded within structures," said Professor Gordon Garmire of Penn State University, and principal investigator of the Advanced CCD Imaging Spectrometer, the X-ray camera that was used to make two of the images. NASA's project scientist, Dr. Martin Weisskopf of the Marshall Space Flight Center said, "Chandra's capability to provide surprises and insights continues." PSR 0540-69 PSR 0540-69 The existence of a rotating neutron star, or pulsar, in the center of G21.5-0.9 is inferred from the appearance of the nebula and the energy distribution of X-rays and radio

THE LIGHT CURVE AND INTERNAL MAGNETIC FIELD OF THE MODE-SWITCHING PULSAR PSR B0943+10

Energy Technology Data Exchange (ETDEWEB)

Storch, Natalia I.; Lai, Dong [Center for Space Research, Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Ho, Wynn C. G. [Mathematical Sciences and STAG Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Heinke, Craig O. [Department of Physics, University of Alberta, CCIS 4-181, Edmonton, AB, T6G 2E1 (Canada)

2014-07-10

A number of radio pulsars exhibit intriguing mode-switching behavior. Recent observations of PSR B0943+10 revealed correlated radio and X-ray mode switches, providing a new avenue for understanding this class of objects. The large X-ray pulse fraction observed during the radio-quiet phase (Q-mode) was previously interpreted as a result of changing obscuration of X-rays by dense magnetosphere plasma. We show that the large X-ray pulse fraction can be explained by including the beaming effect of a magnetic atmosphere, while remaining consistent with the dipole field geometry constrained by radio observations. We also explore a more extreme magnetic field configuration, where a magnetic dipole displaced from the center of the star produces two magnetic polar caps of different sizes and magnetic field strengths. These models are currently consistent with data in radio and X-rays and can be tested or constrained by future X-ray observations.

Observaciones en la banda de radio de los alrededores de PSR J1646-4346 y PSR J1709-4428

Science.gov (United States)

Giacani, E.; Vieytes, M.

It is generally accepted that most of the rotational energy loss of pulsars appears in the form of a relativistic wind of electron-positron pairs. Under certain conditions, the interaction between this wind and its surroundings is observable in the form of a pulsar wind nebula (PWN). At radio wavelenghts, there are at least two morphological types of PWN, depending on the source of confinement for the wind, but all of them present two unmistakable properties: a) high degree of polarization (>5%) and b) flat radio spectral index (0.0 pulsar. We report on VLA high resolution observations of a region around the pulsars PSR J1645-4346 and PSR J1709-4428 at 1.4, 4.8 and 8.4 GHz. The pulsars appear surrounded by a synchrotron nebula. We argue on the basis of morphology, spectral index and polarization propierties that they are the synchrotron nebulae produced by the spin-down energy of the pulsar.

A PRECISE MASS MEASUREMENT OF THE INTERMEDIATE-MASS BINARY PULSAR PSR J1802 - 2124

International Nuclear Information System (INIS)

Ferdman, R. D.; Cognard, I.; Desvignes, G.; Theureau, G.; Stairs, I. H.; Kramer, M.; McLaughlin, M. A.; Lorimer, D. R.; Nice, D. J.; Manchester, R. N.; Hobbs, G.; Lyne, A. G.; Faulkner, A.; Camilo, F.; Possenti, A.; Demorest, P. B.; Backer, D. C.

2010-01-01

PSR J1802 - 2124 is a 12.6 ms pulsar in a 16.8 hr 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 WD mass measurements of 1.24 ± 0.11 M sun and 0.78 ± 0.04 M sun (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.

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.

GMRT Galactic Plane Pulsar and Transient Survey and the Discovery of PSR J1838+1523

Science.gov (United States)

Surnis, Mayuresh P.; Joshi, Bhal Chandra; McLaughlin, Maura A.; Lorimer, Duncan R.; M A, Krishnakumar; Manoharan, P. K.; Naidu, Arun

2018-05-01

We report the results of a blind pulsar survey carried out with the Giant Metrewave Radio Telescope (GMRT) at 325 MHz. The survey covered about 10% of the region between Galactic longitude 45° pulsars. One of these, PSR J1838+1523, was previously unknown and has a period of 549 ms and a dispersion measure of 68 pc cm-3. We also present the timing solution of this pulsar obtained from multi-frequency timing observations carried out with the GMRT and the Ooty Radio Telescope. The measured flux density of this pulsar is 4.3±1.8 and 1.2±0.7 mJy at 325 and 610 MHz, respectively. This implies a spectral index of -2 ±0.8, thus making the expected flux density at 1.4 GHz to be about 0.2 mJy, which would be just detectable in the high frequency pulsar surveys like the Northern High Time Resolution Universe pulsar survey. This discovery underlines the importance of low frequency pulsar surveys in detecting steep spectrum pulsars, thus providing complementary coverage of the pulsar population.

Pulsar bi-drifting: implications for polar cap geometry

Science.gov (United States)

Wright, Geoff; Weltevrede, Patrick

2017-01-01

For many years it has been considered puzzling how pulsar radio emission, supposedly created by a circulating carousel of sub-beams, can produce the drift bands demonstrated by PSR J0815+0939, and more recently PSR B1839-04, which simultaneously drifts 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 polarization 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, accompanying a mode change (e.g. PSR B0943+10), or more gradually and short lived as in `flare' pulsars (e.g. PSR B1859+07). A range of pulsar behaviour (e.g. the shifting drift patterns of PSRs B0818-41 and B0826-34) may also be the result of non-circular carousels with varying orientation. The underlying nature of these carousels - whether they are exclusively generated by polar cap physics or driven by magnetospheric effects - is briefly discussed.

Probing the properties of the pulsar wind via studying the dispersive effects in the pulses from the pulsar companion in a double neutron-star binary system

Science.gov (United States)

Yi, Shu-Xu; Cheng, K.-S.

2017-12-01

The velocity and density distribution of e± in the pulsar wind are crucial distinction among magnetosphere models, and contain key parameters determining the high-energy emission of pulsar binaries. In this work, a direct method is proposed, which might probe the properties of the wind from one pulsar in a double-pulsar binary. When the radio signals from the first-formed pulsar travel through the relativistic e± flow in the pulsar wind from the younger companion, the components of different radio frequencies will be dispersed. It will introduce an additional frequency-dependent time-of-arrival delay of pulses, which is function of the orbital phase. In this paper, we formulate the above-mentioned dispersive delay with the properties of the pulsar wind. As examples, we apply the formula to the double-pulsar system PSR J0737-3039A/B and the pulsar-neutron star binary PSR B1913+16. For PSR J0737-3039A/B, the time delay in 300 MHz is ≲ 10 μ s-1 near the superior conjunction, under the optimal pulsar wind parameters, which is approximately half of the current timing accuracy. For PSR B1913+16, with the assumption that the neutron-star companion has a typical spin-down luminosity of 1033 erg s-1, the time delay is as large as 10 - 20 μ s-1 in 300 MHz. The best timing precision of this pulsar is ∼ 5 μ s-1 in 1400 MHz. Therefore, it is possible that we can find this signal in archival data. Otherwise, we can set an upper limit on the spin-down luminosity. Similar analysis can be applied to other 11 known pulsar-neutron star binaries.

Low-frequency pulse profile variation in PSR B2217+47: evidence for echoes from the interstellar medium

Science.gov (United States)

Michilli, D.; Hessels, J. W. T.; Donner, J. Y.; Grießmeier, J.-M.; Serylak, M.; Shaw, B.; Stappers, B. W.; Verbiest, J. P. W.; Deller, A. T.; Driessen, L. N.; Stinebring, D. R.; Bondonneau, L.; Geyer, M.; Hoeft, M.; Karastergiou, A.; Kramer, M.; Osłowski, S.; Pilia, M.; Sanidas, S.; Weltevrede, P.

2018-05-01

We have observed a complex and continuous change in the integrated pulse profile of PSR B2217+47, manifested as additional components trailing the main peak. These transient components are detected over 6 yr at 150 MHz using the LOw Frequency ARray (LOFAR), but they are not seen in contemporaneous Lovell observations at 1.5 GHz. We argue that propagation effects in the ionized interstellar medium (IISM) are the most likely cause. The putative structures in the IISM causing the profile variation are roughly half-way between the pulsar and the Earth and have transverse radii R ˜ 30 au. We consider different models for the structures. Under the assumption of spherical symmetry, their implied average electron density is \\overline{n}_e ˜ 100 cm-3. Since PSR B2217+47 is more than an order of magnitude brighter than the average pulsar population visible to LOFAR, similar profile variations would not have been identified in most pulsars, suggesting that subtle profile variations in low-frequency profiles might be more common than we have observed to date. Systematic studies of these variations at low frequencies can provide a new tool to investigate the proprieties of the IISM and the limits to the precision of pulsar timing.

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.;

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

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

Indian Academy of Sciences (India)

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 ...

Mid-UV studies of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states

Science.gov (United States)

Rivera Sandoval, L. E.; Hernández Santisteban, J. V.; Degenaar, N.; Wijnands, R.; Knigge, C.; Miller, J. M.; Reynolds, M.; Altamirano, D.; van den Berg, M.; Hill, A.

2018-05-01

We report mid-UV (MUV) observations taken with Hubble Space Telescope (HST)/WFC3, Swift/UVOT, and GALEX/NUV of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states. Both systems were detected in our images and showed MUV variability. At similar orbital phases, the MUV luminosities of both pulsars are comparable. This suggests that the emission processes involved in both objects are similar. We estimated limits on the mass ratio, companion's temperature, inclination, and distance to XSS J12270-4859 by using a Markov Chain Monte Carlo algorithm to fit published folded optical light curves. Using the resulting parameters, we modelled MUV light curves in our HST filters. The resulting models failed to fit our MUV observations. Fixing the mass ratio of XSS J12270-4859 to the value reported in other studies, we obtained a distance of ˜3.2 kpc. This is larger than the one derived from dispersion measure (˜1.4 kpc). Assuming a uniform prior for the mass ratio, the distance is similar to that from radio measurements. However, it requires an undermassive companion (˜0.01M⊙). We conclude that a direct heating model alone cannot fully explain the observations in optical and MUV. Therefore, an additional radiation source is needed. The source could be an intrabinary shock which contributes to the MUV flux and likely to the optical one as well. During the radio pulsar state, the MUV orbital variations of PSR J1023+0038 detected with GALEX, suggest the presence of an asymmetric intrabinary shock.

Search for VHE γ-ray emission from the direction of the two millisecond pulsars PSR J0437-4715 and PSR J1824-2452 and the composite supernova remnant Kes 75 with H.E.S.S

International Nuclear Information System (INIS)

Fuessling, Matthias

2012-01-01

This work reports on the search for pulsed and steady very-high energy (VHE) gamma-ray emission in the energy range extending from 100 GeV up to 100 TeV from the direction of three pulsars with the High Energy Stereoscopic System (H.E.S.S.). Pulsed gamma-ray radiation from pulsars with energies beyond 100 GeV was found thus far only for the young and energetic Crab pulsar. A special class of pulsar wind nebulae (PWNe) is associated with composite supernova remnants (SNRs) where the PWN is centered in an expanding SNR shell. In the first part of this thesis, the results on the search for pulsed and steady VHE gamma-ray emission from the two millisecond pulsars, PSR J0437-4715 and PSR J1824-2452, are presented. Parts of the observations were conducted in a special trigger setup (the topological trigger with convergent pointing) to reduce the energy threshold of the instrument. No signal of pulsed or steady emission is found and upper limits on the pulsed and steady gamma-ray flux are derived. The upper limits on the pulsed gamma-ray flux are compared to existing model predictions and, in the case of PSR J1824-2452, allow the range of possible viewing geometries in some models to be constrained. In the second part of this work, results on the search for pulsed and steady VHE gamma-ray emission from the direction of the composite SNR Kes 75 are presented. The PWN in the center of Kes 75 is powered by a very young and powerful pulsar, PSR J1846-0258, that has an exceptionally high magnetic field. While no hint for pulsed emission is found, steady VHE gamma-ray emission is detected with a statistical significance of 10 sigma from a point-like source. The VHE gamma-ray emission is spatially coincident with the PWN and the SNR shell. Both are discussed as a possible origin for the observed emission. The pulsar of Kes 75 would be the youngest pulsar known to date to power a VHE PWN.

PSR J2322-2650 - a low-luminosity millisecond pulsar with a planetary-mass companion

Science.gov (United States)

Spiewak, R.; Bailes, M.; Barr, E. D.; Bhat, N. D. R.; Burgay, M.; Cameron, A. D.; Champion, D. J.; Flynn, C. M. L.; Jameson, A.; Johnston, S.; Keith, M. J.; Kramer, M.; Kulkarni, S. R.; Levin, L.; Lyne, A. G.; Morello, V.; Ng, C.; Possenti, A.; Ravi, V.; Stappers, B. W.; van Straten, W.; Tiburzi, C.

2018-03-01

We present the discovery of a binary millisecond pulsar (MSP), PSR J2322-2650, found in the southern section of the High Time Resolution Universe survey. This system contains a 3.5-ms pulsar with a ˜10-3 M⊙ companion in a 7.75-h circular orbit. Follow-up observations at the Parkes and Lovell telescopes have led to precise measurements of the astrometric and spin parameters, including the period derivative, timing parallax, and proper motion. PSR J2322-2650 has a parallax of 4.4 ± 1.2 mas, and is thus at an inferred distance of 230^{+90}_{-50} pc, making this system a candidate for optical studies. We have detected a source of R ≈ 26.4 mag at the radio position in a single R-band observation with the Keck telescope, and this is consistent with the blackbody temperature we would expect from the companion if it fills its Roche lobe. The intrinsic period derivative of PSR J2322-2650 is among the lowest known, 4.4(4) × 10-22 s s-1, implying a low surface magnetic field strength, 4.0(4) × 107 G. Its mean radio flux density of 160 μJy combined with the distance implies that its radio luminosity is the lowest ever measured, 0.008(5) mJy kpc2. The inferred population of these systems in the Galaxy may be very significant, suggesting that this is a common MSP evolutionary path.

Interstellar scintillations of PSR B1919+21: space-ground interferometry

Science.gov (United States)

Shishov, V. I.; Smirnova, T. V.; Gwinn, C. R.; Andrianov, A. S.; Popov, M. V.; Rudnitskiy, A. G.; Soglasnov, V. A.

2017-07-01

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 radio telescope, together with two ground telescopes: Westerbork (WB) and Green Bank (GB). The maximum baseline projection for the space-ground interferometer was about 60 000 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 z1 = 440 pc from the observer or homogeneously distributed scattering material to the pulsar; and weak scintillations from a screen located near the observer at z2 = 0.14 ± 0.05 pc. Furthermore, in the direction to the pulsar we detected a prism that deflects radiation, leading to a shift in 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 a scattering angle in the observer plane of θscat = 0.7 mas. An analysis of the time-frequency correlation function for weak scintillations yielded an angle of refraction in the direction to the pulsar θref, 0 = 110 ms and a distance to the prism zprism ≤ 2 pc.

A NuSTAR Observation of the Gamma-Ray Emitting Millisecond Pulsar PSR J1723–2837

Energy Technology Data Exchange (ETDEWEB)

Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Hui, C. Y. [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Takata, J. [Institute of Particle Physics and Astronomy, Huazhong University of Science and Technology (China); Li, K. L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Tam, P. H. T., E-mail: akong@phys.nthu.edu.tw, E-mail: cyhui@cnu.ac.kr [School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082 (China)

2017-04-20

We report on the first NuSTAR observation of the gamma-ray emitting millisecond pulsar binary PSR J1723–2837. X-ray radiation up to 79 keV is clearly detected, and the simultaneous NuSTAR and Swift spectrum is well described by an absorbed power law with a photon index of ∼1.3. We also find X-ray modulations in the 3–10, 10–20, 20–79, and 3–79 keV bands at the 14.8 hr binary orbital period. All of these are entirely consistent with previous X-ray observations below 10 keV. This new hard X-ray observation of PSR J1723–2837 provides strong evidence that the X-rays are from the intrabinary shock via an interaction between the pulsar wind and the outflow from the companion star. We discuss how the NuSTAR observation constrains the physical parameters of the intrabinary shock model.

Improved timing of the millisecond pulsar PSR 1937+21 using real-time coherent dedispersion

International Nuclear Information System (INIS)

Hankins, T.H.; Stinebring, D.R.; Rawley, L.A.; Princeton Univ., NJ)

1987-01-01

Profiles of the millisecond pulsar PSR 1937+21 have been obtained with 6-micron resolution using a real-time hardware dispersion removal device. This dedisperser has a potential resolution of better than 0.5 microsec and is immune to time-of-arrival jitter caused by scintillation-induced spectral gradients across the receiver passband. It significantly reduces the time-of-arrival residuals when compared with the timing technique currently in use. This increased timing accuracy, when utilized in a long-term timing program of millisec pulsars, will improve the solar system ephemeris and will substantially improve the detection limit of a gravitational wave background. 27 references

Anti-correlated X-ray and Radio Variability in the Transitional Millisecond Pulsar PSR J1023+0038

Science.gov (United States)

Bogdanov, Slavko; Deller, Adam; Miller-Jones, James; Archibald, Anne; Hessels, Jason W. T.; Jaodand, Amruta; Patruno, Alessandro; Bassa, Cees; D'Angelo, Caroline

2018-01-01

The PSR J1023+0038 binary system hosts a 1.69-ms neutron star and a low-mass, main-sequence-like star. The system underwent a transformation from a rotation-powered to a low-luminosity accreting state in 2013 June, in which it has remained since. We present an unprecedented set of strictly simultaneous Chandra X-ray Observatory and Karl G. Jansky Very Large Array observations, which for the first time reveal a highly reproducible, anti-correlated variability pattern. Rapid declines in X-ray flux are always accompanied by a radio brightening with duration that closely matches the low X-ray flux mode intervals. We discuss these findings in the context of accretion and jet outflow physics and their implications for using the radio/X-ray luminosity plane to distinguish low-luminosity candidate black hole binary systems from accreting transitional millisecond pulsars.

Hidden slow pulsars in binaries

Science.gov (United States)

Tavani, Marco; Brookshaw, Leigh

1993-01-01

The recent discovery of the binary containing the slow pulsar PSR 1718-19 orbiting around a low-mass companion star adds new light on the characteristics of binary pulsars. The properties of the radio eclipses of PSR 1718-19 are the most striking observational characteristics of this system. The surface of the companion star produces a mass outflow which leaves only a small 'window' in orbital phase for the detection of PSR 1718-19 around 400 MHz. At this observing frequency, PSR 1718-19 is clearly observable only for about 1 hr out of the total 6.2 hr orbital period. The aim of this Letter is twofold: (1) to model the hydrodynamical behavior of the eclipsing material from the companion star of PSR 1718-19 and (2) to argue that a population of binary slow pulsars might have escaped detection in pulsar surveys carried out at 400 MHz. The possible existence of a population of partially or totally hidden slow pulsars in binaries will have a strong impact on current theories of binary evolution of neutron stars.

On the timing behaviour of PSR B1259-63 under the propeller torque from a transient accretion disc

Science.gov (United States)

Yi, Shu-Xu; Cheng, K. S.

2018-05-01

The γ-ray pulsar binary system PSR B1259-63 flares in GeV after each periastron. The origin of these flares is still under debate. Recently, in 2017, we proposed a mechanism that might explain the GeV flares. In that model, a transient accretion disc is expected to be formed from the matter that was gravity-captured by the neutron star from the main-sequence companion's circumstellar disc. The transient accretion disc exerts a spin-down torque on the neutron star (i.e. the propeller effect), which might be traceable via pulsar timing observations of PSR B1259-63. In this paper, we consider the propeller effect phenomenologically using a parameter χ, which describes the coupling between the disc matter and the neutron star. Comparing the expected timing residuals with recent observations by Shannon et al., we conclude that the angular momentum transfer is very weak (with the coupling parameter χ ≤ 10-4).

Variations of the harmonic components of the X-ray pulse profile of PSR B1509–58

International Nuclear Information System (INIS)

Pradhan Pragati; Paul Biswajit; Raichur Harsha; Paul Bikash Chandra

2015-01-01

We used the Fourier decomposition technique to investigate the stability of the X-ray pulse profile of a young pulsar PSR B1509–58 by studying the relative amplitudes and phase differences of its harmonic components with respect to the fundamental using data from the Rossi X-Ray Timing Explorer. Like most young rotation powered pulsars, PSR B1509–58 has a high spin down rate. It also has less timing noise, allowing accurate measurement of higher order frequency derivatives which in turn helps in the study of the physics of pulsar spin down. Detailed investigation of pulse profiles over the years will help us establish any possible connection between the timing characteristics and the high energy emission characteristics for this pulsar. Furthermore, the study of pulse profiles of short period X-ray pulsars can also be useful when used as a means of interplanetary navigation. The X-ray pulse profile of this source has been analyzed for 15 yr (1996–2011). The long term average amplitudes of the first, second and third harmonics (and their standard deviation for individual measurements) compared to the fundamental are 36.9% (1.7%), 13.4% (1.9%) and 9.4% (1.8%) respectively. Similarly, the phases of the three harmonics (and standard deviations) with respect to the fundamental are 0.36 (0.06), 1.5 (0.2) and 2.5 (0.3) radian respectively. We do not find any significant variation of the harmonic components of the pulse profile in comparison to the fundamental. (research papers)

Giant Pulse Studies of Ordinary and Recycled Pulsars with NICER

Science.gov (United States)

Lewandowska, Natalia; Arzoumanian, Zaven; Gendreau, Keith C.; Enoto, Teruaki; Harding, Alice; Lommen, Andrea; Ray, Paul S.; Deneva, Julia; Kerr, Matthew; Ransom, Scott M.; NICER Team

2018-01-01

Radio Giant Pulses are one of the earliest discovered form of anomalous single pulse emission from pulsars. Known for their non-periodical occurrence, restriction to certain phase ranges, power-law intensity distributions, pulse widths ranging from microseconds to nanoseconds and very high brightness temperatures, they stand out as an individual form of pulsar radio emission.Discovered originally in the case of the Crab pulsar, several other pulsars have been observed to emit radio giant pulses, the most promising being the recycled pulsar PSR B1937+21 and also the Vela pulsar.Although radio giant pulses are apparently the result of a coherent emission mechanism, recent studies of the Crab pulsar led to the discovery of an additional incoherent component at optical wavelengths. No such component has been identified for recycled pulsars, or Vela yet.To provide constraints on possible emission regions in their magnetospheres and to search for differences between giant pulses from ordinary and recycled pulsars, we present the progress of the correlation study of PSR B1937+21 and the Vela pulsar carried out with NICER and several radio observatories.

Chandra and RXTE studies of the X-ray/gamma-ray millisecond pulsar PSR J0218+4232

NARCIS (Netherlands)

Kuiper, L.; Hermsen, W.; Stappers, B.W.

2004-01-01

We report on high-resolution spatial and timing observations of the millisecond pulsar PSR J0218+4232 performed with the Chandra X-ray Observatory (CXO) and the Rossi X-ray Timing Explorer (RXTE). With these observations we were able to study: (a) the possible spatial extent at X-ray energies of the

The 26.3-h orbit and multiwavelength properties of the `redback' millisecond pulsar PSR J1306-40

Science.gov (United States)

Linares, Manuel

2018-01-01

We present the discovery of the variable optical and X-ray counterparts to the radio millisecond pulsar (MSP) PSR J1306-40, recently discovered by Keane et al. We find that both the optical and X-ray fluxes are modulated with the same period, which allows us to measure for the first time the orbital period Porb = 1.097 16[6] d. The optical properties are consistent with a main-sequence companion with spectral type G to mid K and, together with the X-ray luminosity (8.8 × 1031 erg s-1 in the 0.5-10 keV band, for a distance of 1.2 kpc), confirm the redback classification of this pulsar. Our results establish the binary nature of PSR J1306-40, which has the longest Porb among all known compact binary MSPs in the Galactic disc. We briefly discuss these findings in the context of irradiation and intrabinary shock emission in compact binary MSPs.

Rossi X-Ray Timing Explorer Observation of PSR B0656+14

International Nuclear Information System (INIS)

Chang, H.; Ho, C.

1999-01-01

PSR B0656+14 was observed by the Rossi X-Ray Timing Explorer (RXTE) with the proportional counter array (PCA) and the high-energy X-ray timing experiment (HEXTE) for 160 ks during 1997 August 22 - September 3. No pulsation was firmly found in the timing analysis, during which the contemporaneous radio ephemeris and various statistical tests were applied in searching for evidence of pulsation. A marginal detection of pulsation at a confidence level of 95.5% based on the H test was found with data in the whole HEXTE energy band. In the energy band of 2-10 keV the RXTE PCA upper limits are about 1 order of magnitude lower than that from ASCA GIS data. If the Compton Gamma Ray Observatory EGRET detection of this pulsar is real, considering the common trait that most EGRET-detected pulsars have a cooling spectrum in hard X-ray and gamma-ray energy bands, the estimated RXTE upper limits indicate a deviation (low-energy turnover) from a cooling spectrum starting from 20 keV or higher. This in turn suggests an outer magnetospheric synchrotron radiation origin for high-energy emissions from PSR B0656+14. The RXTE PCA upper limits also suggest that a reported power-law component based on ASCA SIS data in 1-10 keV fitted jointly with ROSAT data, if real, should be mainly unpulsed. copyright copyright 1999. The American Astronomical Society

A New Approach to the GeV Flare of PSR B1259-63/LS2883

Energy Technology Data Exchange (ETDEWEB)

Yi, Shu-Xu; Cheng, K. S., E-mail: yishuxu@hku.hk, E-mail: hrspksc@hku.hk [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong)

2017-08-01

PSR B1259-63/LS2883 is a binary system composed of a pulsar and a Be star. The Be star has an equatorial circumstellar disk (CD). The Fermi satellite discovered unexpected gamma-ray flares around 30 days after the last two periastron passages. The origin of the flares remains puzzling. In this work, we explore the possibility that the GeV flares are consequences of inverse Compton scattering of soft photons by the pulsar wind. The soft photons are from an accretion disk around the pulsar, which is composed of the matter from the CD captured by the pulsar’s gravity at disk-crossing before the periastron. At the other disk-crossing after the periastron, the density of the CD is not high enough, so accretion is prevented by the pulsar wind shock. This model can reproduce the observed spectrum energy distributions and light curves satisfactorily.

THE PULSAR SEARCH COLLABORATORY: DISCOVERY AND TIMING OF FIVE NEW PULSARS

Energy Technology Data Exchange (ETDEWEB)

Rosen, R.; Swiggum, J.; McLaughlin, M. A.; Lorimer, D. R.; Yun, M.; Boyles, J. [West Virginia University, White Hall, Morgantown, WV 26506 (United States); Heatherly, S. A.; Scoles, S. [NRAO, P.O. Box 2, Green Bank, WV 24944 (United States); Lynch, R. [McGill University, Rutherford Physics Building, 3600 Rue University, Montreal, QC H3A 2T8 (Canada); Kondratiev, V. I. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo (Netherlands); Ransom, S. M. [NRAO, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Moniot, M. L.; Thompson, C. [James River High School, 9906 Springwood Road, Buchanan, VA 24066 (United States); Cottrill, A.; Raycraft, M. [Lincoln High School, 100 Jerry Toth Drive, Shinnston, WV 26431 (United States); Weaver, M. [Broadway High School, 269 Gobbler Drive, Broadway, VA 22815 (United States); Snider, A. [Sherando High School, 185 South Warrior Drive, Stephens City, VA 22655 (United States); Dudenhoefer, J.; Allphin, L. [Hedgesville High School, 109 Ridge Road North, Hedgesville, WV 25427 (United States); Thorley, J., E-mail: Rachel.Rosen@mail.wvu.edu [Strasburg High School, 250 Ram Drive, Strasburg, VA 22657 (United States); and others

2013-05-01

We present the discovery and timing solutions of five new pulsars by students involved in the Pulsar Search Collaboratory, 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 hr of drift-scan survey data taken with the Green Bank Telescope at 350 MHz. These data cover 2876 deg{sup 2} 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, nulling pulsar; PSR J1821+0155, an isolated, partially recycled 33 ms pulsar; and PSR J1400-1438, a millisecond pulsar in a 9.5 day orbit whose companion is likely a white dwarf star.

What ionizes the interstellar hydrogen toward PSR 0950 + 08 and PSR 0823 + 26?

International Nuclear Information System (INIS)

Reynolds, R.J.

1990-01-01

Neither H II regions around nearby B stars nor known white dwarf stars can account for the free electron column densities along two well-defined line segments to the pulsars PSR 0950 + 08 and PSR 0823 + 26. The presence of the ionized gas seems to imply either (1) very long mean free path lengths for the absorption of Lyman continuum photons within the ISM (thereby suggesting a very different morphology for interstellar H I from that of the conventional view); or (2) Lyman continuum luminosities for early B or hot white dwarf stars that are more than an order of magnitude larger than currently accepted values; or (3) an additional and as yet unknown ionization source within the Galactic disk. 54 refs

The TeV γ-ray binary PSR B1259-63. Observations with the high energy stereoscopic system in the years 2005-2007

International Nuclear Information System (INIS)

Kerschhaggl, Matthias

2010-01-01

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 γ-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 γ-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 stat ±0.2 sys and flux normalisation Φ 0 =(1.1±0.1 stat ±0.2 sys ) x 10 -12 TeV -1 cm -2 s -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 γ-rays is seen in those observations. PSR B1259-63 has been re-confirmed as a variable TeV γ-ray emitter. The firm detection of VHE photons emitted at a true anomaly θ∼0.35 of the pulsar orbit, i.e. already ∝50 days prior to the periastron passage, disfavors the stellar disc target scenario as a primary emission mechanism, based on current knowledge about the companion star's disc inclination, extension, and density profile. In a phenomenological study indirect evidence that PSR B1259-63 could in fact be a periodical VHE emitter is presented using the TeV data discussed in this work. While the TeV energy flux level seems to be only dependent on the binary separation this behavior is not seen in X-rays. Moreover, model calculations based on inverse compton (IC) scattering of

A VERY LARGE GLITCH IN PSR B2334+61

International Nuclear Information System (INIS)

Yuan, J. P.; Wang, N.; Zhou, X.; Liu, Z. Y.; Gao, Z. F.; Manchester, R. N.

2010-01-01

Seven year pulse time-of-arrival measurements have been collected from observations of the young pulsar PSR B2334+61 using the Nanshan radio telescope of Urumqi Observatory. A phase-connected solution has been obtained over the whole data span, 2002 August to 2009 August. This includes a very large glitch that occurred between 2005 August 26 and September 8 (MJDs 53608 and 53621). The relative increase in rotational frequency for this glitch, Δν g /ν ∼ 20.5 x 10 -6 , is the largest ever seen. Although accounting for less than 1% of the glitch, there were two well-defined exponential decay terms with time constants of 21 and 147 days, respectively. There was also a large long-term increase in the spin-down rate with Δν-dit p /ν-dot ∼0.011 at the time of the glitch. A highly significant oscillation with a period of close to one year is seen in the post-glitch residuals. It is very unlikely that this can be accounted for by a pulsar position error or proper motion-it appears to result from effects interior to the neutron star. Implications of these results for pulsar glitch models are discussed.

Multiwavelength Spectroscopy of PSR B0656+14

Science.gov (United States)

Durant, Martin; Kargaltsev, Oleg; Pavlov, George G.

2011-12-01

Using high-quality Hubble Space Telescope observations, we construct the near-infrared (NIR) to far-ultraviolet (FUV) spectral energy distribution (SED) of PSR B0656+14. The SED is non-monotonic. Fitting it with a simple combination of a Rayleigh-Jeans spectrum (UV) and non-thermal power law (PL; optical/NIR) leaves significant residuals, strongly hinting at one or more spectral features. We consider various models (combination of continuum components, and absorption/emission lines) with possible interpretations and place them in the context of the broader SED. Surprisingly, the extrapolation of the best-fit X-ray spectral model roughly matches the NIR-FUV data, and the PL component is also consistent with the γ-ray fluxes. We compare the multiwavelength SED of B0656+14 with those of other optical-, X-ray-, and γ-ray-detected pulsars, and notice that a simple PL spectrum crudely accounts for most of the non-thermal emission.

MULTIWAVELENGTH SPECTROSCOPY OF PSR B0656+14

International Nuclear Information System (INIS)

Durant, Martin; Kargaltsev, Oleg; Pavlov, George G.

2011-01-01

Using high-quality Hubble Space Telescope observations, we construct the near-infrared (NIR) to far-ultraviolet (FUV) spectral energy distribution (SED) of PSR B0656+14. The SED is non-monotonic. Fitting it with a simple combination of a Rayleigh-Jeans spectrum (UV) and non-thermal power law (PL; optical/NIR) leaves significant residuals, strongly hinting at one or more spectral features. We consider various models (combination of continuum components, and absorption/emission lines) with possible interpretations and place them in the context of the broader SED. Surprisingly, the extrapolation of the best-fit X-ray spectral model roughly matches the NIR-FUV data, and the PL component is also consistent with the γ-ray fluxes. We compare the multiwavelength SED of B0656+14 with those of other optical-, X-ray-, and γ-ray-detected pulsars, and notice that a simple PL spectrum crudely accounts for most of the non-thermal emission.

Is the apparent dichotomy between bursting activity of magnetars and radio pulsars real ?

International Nuclear Information System (INIS)

Pons, J A; Perna, R

2012-01-01

Anomalous X-ray Pulsars (AXPs) and Soft Gamma-Ray Repeaters (SGRs) are a class of young neutron stars (NSs) characterized by high X-ray quiescent luminosities, short X-ray bursts, and giant flares (for SGRs). They are believed to be magnetars, i.e. NSs with magnetic fields ∼ 10 14 – 10 15 G. The discovery of magnetar-like X-ray bursts from the young pulsar PSR J1846-0258 [1], with an inferred surface dipolar magnetic field of B p = 4.9 × 10 13 G, lower than the traditionally considered magnetar range, and, more recently, by the discovery of SGR 0418+5729 with an even lower B p = 7.5 × 10 12 G [2], well within the range of the rotation powered pulsars which do not display any bursting behaviour, has raised the obvious question: why some 'high-B' pulsars (PSR J1119-6127 and PSR J1814-1744, with B ∼ 4 – 5 × 10 13 G) do not display any burst, while at least one case of 'low-B' NSs (SGR 0418+5729) does, if the magnetic field is their driving force ?

A PROPELLER MODEL FOR THE SUB-LUMINOUS STATE OF THE TRANSITIONAL MILLISECOND PULSAR PSR J1023+0038

Energy Technology Data Exchange (ETDEWEB)

Papitto, A.; Torres, D. F. [Institute of Space Sciences (CSIC-IEEC), Campus UAB, Carrer de Can Magrans, S/N, E-08193, Cerdanyola del Vallés, Barcelona (Spain)

2015-07-01

The discovery of millisecond pulsars switching between states powered either by the rotation of their magnetic field or by the accretion of matter has recently proved the tight link shared by millisecond radio pulsars and neutron stars in low-mass X-ray binaries. Transitional millisecond pulsars also show an enigmatic intermediate state in which the neutron star is surrounded by an accretion disk and emits coherent X-ray pulsations, but is sub-luminous in X-rays with respect to accreting neutron stars, and is brighter in gamma-rays than millisecond pulsars in the rotation-powered state. Here, we model the X-ray and gamma-ray emission observed from PSR J1023+0038 in such a state based on the assumptions that most of the disk in-flow is propelled away by the rapidly rotating neutron star magnetosphere, and that electrons can be accelerated to energies of a few GeV at the turbulent disk–magnetosphere boundary. We show that the synchrotron and self-synchrotron Compton emission coming from such a region, together with the hard disk emission typical of low states of accreting compact objects, is able to explain the radiation observed in the X-ray and gamma-ray bands. The average emission observed from PSR J1023+0038 is modeled by a disk in-flow with a rate of 1–3 × 10{sup −11} M{sub ⊙} yr{sup −1}, truncated at a radius ranging between 30 and 45 km, compatible with the hypothesis of a propelling magnetosphere. We compare the results we obtained with models that assume that a rotation-powered pulsar is turned on, showing how the spin-down power released in similar scenarios is hardly able to account for the magnitude of the observed emission.

THE PULSAR SEARCH COLLABORATORY: DISCOVERY AND TIMING OF FIVE NEW PULSARS

International Nuclear Information System (INIS)

Rosen, R.; Swiggum, J.; McLaughlin, M. A.; Lorimer, D. R.; Yun, M.; Boyles, J.; Heatherly, S. A.; Scoles, S.; Lynch, R.; Kondratiev, V. I.; Ransom, S. M.; Moniot, M. L.; Thompson, C.; Cottrill, A.; Raycraft, M.; Weaver, M.; Snider, A.; Dudenhoefer, J.; Allphin, L.; Thorley, J.

2013-01-01

We present the discovery and timing solutions of five new pulsars by students involved in the Pulsar Search Collaboratory, 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 hr of drift-scan survey data taken with the Green Bank Telescope at 350 MHz. These data cover 2876 deg 2 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, nulling pulsar; PSR J1821+0155, an isolated, partially recycled 33 ms pulsar; and PSR J1400–1438, a millisecond pulsar in a 9.5 day orbit whose companion is likely a white dwarf star.

Relativistic spin precession in the double pulsar.

Science.gov (United States)

Breton, Rene P; Kaspi, Victoria M; Kramer, Michael; McLaughlin, Maura A; Lyutikov, Maxim; Ransom, Scott M; Stairs, Ingrid H; Ferdman, Robert D; Camilo, Fernando; Possenti, Andrea

2008-07-04

The double pulsar PSR J0737-3039A/B consists of two neutron stars in a highly relativistic orbit that displays a roughly 30-second eclipse when pulsar A passes behind pulsar B. Describing this eclipse of pulsar A as due to absorption occurring in the magnetosphere of pulsar B, we successfully used a simple geometric model to characterize the observed changing eclipse morphology and to measure the relativistic precession of pulsar B's spin axis around the total orbital angular momentum. This provides a test of general relativity and alternative theories of gravity in the strong-field regime. Our measured relativistic spin precession rate of 4.77 degrees (-0 degrees .65)(+0 degrees .66) per year (68% confidence level) is consistent with that predicted by general relativity within an uncertainty of 13%.

DISCOVERY OF X-RAY PULSATION FROM THE GEMINGA-LIKE PULSAR PSR J2021+4026

Energy Technology Data Exchange (ETDEWEB)

Lin, L. C. C. [General Education Center, China Medical University, Taichung 40402, Taiwan (China); Hui, C. Y.; Seo, K. A., E-mail: cyhui@cnu.ac.kr [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Hu, C. P.; Chou, Y. [Graduate Institute of Astronomy, National Central University, Jhongli 32001, Taiwan (China); Wu, J. H. K.; Huang, R. H. H. [Institute of Astronomy, National Tsing-Hua University, Hsinchu 30013, Taiwan (China); Trepl, L. [Astrophysikalisches Institut und Universitaets-Sternwarte, Universitaet Jena, Schillergaesschen 2-3, D-07745 Jena (Germany); Takata, J.; Wang, Y.; Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong (Hong Kong)

2013-06-10

We report the discovery of an X-ray periodicity of {approx}265.3 ms from a deep XMM-Newton observation of the radio-quiet {gamma}-ray pulsar, PSR J2021+4026, located at the edge of the supernova remnant G78.2+2.1 ({gamma}-Cygni). The detected frequency is consistent with the {gamma}-ray pulsation determined by the observation of the Fermi Gamma-ray Space Telescope at the same epoch. The X-ray pulse profile resembles the modulation of a hot spot on the surface of the neutron star. The phase-averaged spectral analysis also suggests that the majority of the observed X-rays have thermal origins. This is the third member in the class of radio-quiet pulsars with significant pulsations detected from both X-ray and {gamma}-ray regimes.

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.

Radio-quiet Gamma-ray Pulsars

Directory of Open Access Journals (Sweden)

Lupin Chun-Che Lin

2016-09-01

Full Text Available 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 to specified discuss their common and specific features.

The Glitches and Rotational History of the Highly Energetic Young Pulsar PSR J0537–6910

Science.gov (United States)

Ferdman, R. D.; Archibald, R. F.; Gourgouliatos, K. N.; Kaspi, V. M.

2018-01-01

We present a timing and glitch analysis of the young X-ray pulsar PSR J0537‑6910, located within the Large Magellanic Cloud, using 13 yr of data from the now-decommissioned Rossi X-ray Timing Explorer. Rotating with a spin period of 16 ms, PSR J0537‑6910 is the fastest-spinning and most energetic young pulsar known. It also displays the highest glitch activity of any known pulsar. We have found 42 glitches over the data span, corresponding to a glitch rate of 3.2 yr‑1, with an overall glitch activity rate of 8.8× {10}-7 {{yr}}-1. The high glitch frequency has allowed us to study the glitch behavior in ways that are inaccessible in other pulsars. We observe a strong linear correlation between spin frequency glitch magnitude and wait time to the following glitch. We also find that the post-glitch spin-down recovery is well described by a single two-component model fit to all glitches for which we have adequate input data. This consists of an exponential amplitude A=(7.6+/- 1.0)× {10}-14 {{{s}}}-2, decay timescale τ ={27}-6+7 {day}s, and linear slope m=(4.1+/- 0.4)× {10}-16 {{{s}}}-2 {{day}}-1. The latter slope corresponds to a second frequency derivative \\ddot{ν }=(4.7+/- 0.5)× {10}-22 {{{s}}}-3, from which we find an implied braking index n=7.4+/- 0.8. We also present a maximum likelihood technique for searching for periods in event-time data, which we used to both confirm previously published values and determine rotation frequencies in later observations. We discuss the implied constraints on glitch models from the observed behavior of this system, which we argue cannot be fully explained in the context of existing theories.

Monitoring PSR B1509–58 with RXTE: Spectral analysis 1996–2010

Directory of Open Access Journals (Sweden)

E. Litzinger

2011-01-01

Full Text Available We present an analysis of the X-ray spectra of the young, Crab-like pulsar PSR B1509–58 (pulse period P ~ 151ms observed by RXTE over 14 years since the beginning of the mission in 1996. The uniform dataset is especially well suited for studying the stability of the spectral parameters over time as well as for determining pulse phase resolved spectral parameters with high significance. The phase averaged spectra as well as the resolved spectra can be well described by an absorbed power law.

Observations of one young and three middle-aged γ-ray pulsars with the Gran Telescopio Canarias

Science.gov (United States)

Mignani, R. P.; Testa, V.; Rea, N.; Marelli, M.; Salvetti, D.; Torres, D. F.; De Oña Wilhelmi, E.

2018-04-01

We used the 10.4m Gran Telescopio Canarias to search for the optical counterparts to four isolated γ-ray pulsars, all detected in the X-rays by either XMM-Newton or Chandra but not yet in the optical. Three of them are middle-aged pulsars - PSR J1846+0919 (0.36 Myr), PSR J2055+2539 (1.2 Myr), PSR J2043+2740 (1.2 Myr) - and one, PSR J1907+0602, is a young pulsar (19.5 kyr). For both PSR J1907+0602 and PSR J2055+2539 we found one object close to the pulsar position. However, in both cases such an object cannot be a viable candidate counterpart to the pulsar. For PSR J1907+0602, because it would imply an anomalously red spectrum for the pulsar and for PSR J2055+2539 because the pulsar would be unrealistically bright (r' = 20.34 ± 0.04) for the assumed distance and interstellar extinction. For PSR J1846+0919, we found no object sufficiently close to the expected position to claim a possible association, whereas for PSR J2043+2740 we confirm our previous findings that the object nearest to the pulsar position is an unrelated field star. We used our brightness limits (g' ≈ 27), the first obtained with a large-aperture telescope for both PSR J1846+0919 and PSR J2055+2539, to constrain the optical emission properties of these pulsars and investigate the presence of spectral turnovers at low energies in their multi-wavelength spectra.

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

Science.gov (United States)

Ng, C.; Champion, D. J.; 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.

2015-07-01

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 redetected 435 previously known pulsars and discovered a further 60 pulsars, two of which are fast-spinning pulsars with periods less than 30 ms. PSR J1101-6424 is a millisecond pulsar whose heavy white dwarf (WD) companion and short spin period of 5.1 ms indicate a rare example of full-recycling via Case A Roche lobe overflow. PSR J1757-27 appears to be an isolated recycled pulsar with a relatively long spin period of 17 ms. In addition, PSR J1244-6359 is a mildly recycled binary system with a heavy WD companion, PSR J1755-25 has a significant orbital eccentricity of 0.09 and PSR J1759-24 is likely to be a long-orbit eclipsing binary with orbital period of the order of tens of years. Comparison of our newly discovered pulsar sample to the known population suggests that they belong to an older population. Furthermore, we demonstrate that our current pulsar detection yield is as expected from population synthesis.

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.

SEARCH FOR VERY HIGH ENERGY GAMMA-RAY EMISSION FROM PULSAR-PULSAR WIND NEBULA SYSTEMS WITH THE MAGIC TELESCOPE

International Nuclear Information System (INIS)

Anderhub, H.; Biland, A.; Antonelli, L. A.; Antoranz, P.; Balestra, S.; Barrio, J. A.; Bose, D.; Backes, M.; Becker, J. K.; Baixeras, C.; Bastieri, D.; Bock, R. K.; Gonzalez, J. Becerra; Bednarek, W.; Berger, K.; Bernardini, E.; Bonnoli, G.; Bordas, P.; Bosch-Ramon, V.; Tridon, D. Borla

2010-01-01

The MAGIC collaboration has searched for high-energy gamma-ray emission of some of the most promising pulsar candidates above an energy threshold of 50 GeV, an energy not reachable up to now by other ground-based instruments. Neither pulsed nor steady gamma-ray emission has been observed at energies of 100 GeV from the classical radio pulsars PSR J0205+6449 and PSR J2229+6114 (and their nebulae 3C58 and Boomerang, respectively) and the millisecond pulsar PSR J0218+4232. Here, we present the flux upper limits for these sources and discuss their implications in the context of current model predictions.

Precision Timing of PSR J0437-4715: An Accurate Pulsar Distance, a High Pulsar Mass, and a Limit on the Variation of Newton's Gravitational Constant

Science.gov (United States)

Verbiest, J. P. W.; Bailes, M.; van Straten, W.; Hobbs, G. B.; Edwards, R. T.; Manchester, R. N.; Bhat, N. D. R.; Sarkissian, J. M.; Jacoby, B. A.; Kulkarni, S. R.

2008-05-01

Analysis of 10 years of high-precision timing data on the millisecond pulsar PSR J0437-4715 has resulted in a model-independent kinematic distance based on an apparent orbital period derivative, dot Pb , determined at the 1.5% level of precision (Dk = 157.0 +/- 2.4 pc), making it one of the most accurate stellar distance estimates published to date. The discrepancy between this measurement and a previously published parallax distance estimate is attributed to errors in the DE200 solar system ephemerides. The precise measurement of dot Pb allows a limit on the variation of Newton's gravitational constant, |Ġ/G| <= 23 × 10-12 yr-1. We also constrain any anomalous acceleration along the line of sight to the pulsar to |a⊙/c| <= 1.5 × 10-18 s-1 at 95% confidence, and derive a pulsar mass, mpsr = 1.76 +/- 0.20 M⊙, one of the highest estimates so far obtained.

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}).

LMXB AND IMXB EVOLUTION: I. THE BINARY RADIO PULSAR PSR J1614-2230

International Nuclear Information System (INIS)

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

2011-01-01

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 cover 60 initial donor masses over the range of 1-4 M sun and, for each of these, 700 initial orbital periods over the range of 10-250 hr. These results can be applied to understanding LMXBs and IMXBs: those that evolve analogously to cataclysmic variables, that form ultracompact binaries with P orb in the range of 6-50 minutes, and 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 M sun neutron star, P orb = 8.7 days, and a companion star of 0.5 M sun . We show that (1) this system is a cousin to the LMXB Cyg X-2; (2) for neutron stars of canonical birth mass 1.4 M sun , the initial donor stars which produce the closest relatives to PSR J1614-2230 have a mass between 3.4 and 3.8 M sun ; (3) neutron stars as massive as 1.97 M sun are not easy to produce in spite of the initially high mass of the donor star, unless they were already born as relatively massive neutron stars; (4) to successfully produce a system like PSR J1614-2230 requires a minimum initial neutron-star mass of at least 1.6 ± 0.1 M sun , as well as initial donor masses and P orb of ∼4.25 ± 0.10 M sun and ∼49 ± 2 hr, respectively; and (5) the current companion star is largely composed of CO, but should have a surface H abundance of ∼10%-15%.

The 2017 Periastron Passage of PSR B1259-63 in Gamma-rays and X-rays

Science.gov (United States)

Wood, Kent S.; Johnson, Tyrel; Ray, Paul S.; Kerr, Matthew T.; Chernyakova, Masha; Fermi LAT Collaboration

2018-01-01

PSR B1259‑ 63 is a 48-ms radio pulsar in a highly eccentric 3.4-yr orbit with a Be star LS 2883. While the pulsed emission has been detected only in radio, un-pulsed radio, X-ray and gamma-ray emission are regularly observed from the binary system around the periastron. It is likely that the collision of the pulsar wind with the anisotropic wind of the Be star plays a crucial role in the generation of the observed non-thermal emission. The spectral energy distribution observed near periastron peaks in GeV gamma-rays, reaching maximum flux several weeks past periastron. In September 2017 it is being observed for a third periastron passage by the Fermi satellite. Here we present first results of the 2017 multi-wavelength campaign. The 2017 observations are compared to the two previous cycles, and used to test current models. Until recently there was no similar source known in the Galaxy but now a near-twin to it, PSR J2032+4127 , (Pspin=143 ms, Porbit ~50 yr, detectable radio to gamma rays) has been found, and is also undergoing periastron passage in Nov 2017. Gamma-ray and X-ray phenomena in the two sources are compared and discussed. These objects may represent a transitional phase, with possible later phases being accreting pulsars, and eventually perhaps NS-BH or NS-NS binary systems. Portions of this research performed at the US Naval Research Laboratory are sponsored by NASA DPR S-15633-Y.

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;

VHE gamma-rays from radio pulsars and cataclysmic variables

International Nuclear Information System (INIS)

De Jager, O.C.; Brink, C.; Meintjies, P.J.; Nel, H.I.; North, A.R.; Raubenheimer, B.C.; Van der Walt, D.J.

1990-01-01

We present the results of observations (above 1 TeV) of radio pulsars and cataclysmic variables with the Potchefstroom air Cerenkov facility. We were able to confirm our previous detection of PSR 1509-58 and the final significance is 1.7x10 -5 . A DC enhancement at the 10 -3 significance level was seen from the L 4 Lagrange position in the PSR 1957+20 system. This result was confirmed by COS-B data. We were also able to detect the 5.4 ms pulsar PSR 1855+09 at a marginal significance level of 5%. However, the best and longest observation indicates non-uniformity at the 0.005 significance level. The TeV light curve resembles the radio light curve. The latter is also reminiscent of other millisecond pulsar observed above 1 TeV. The intermediate polar AEAQR (P = 33.08s) shows a period shift which is consistent with recent model predictions. However, the present significance of this results does not allow an unambiguous claim. (orig.)

High-Cadence Timing Observations of an Exoplanet-Pulsar System, PSR B1257+12

Science.gov (United States)

Rivera, Rudy; Wolszczan, Aleksander; Seymour, Andrew

2016-01-01

The pulsar B1257+12 was regularly observed and timed by Aleksander Wolszczan from its discovery in 1992 up to 2008. It is the first example of an exoplanet-pulsar system, and is modeled to consist of three planets. At the time, long term timing programs lacked the sensitivity to measure effects that low mass, short orbital period bodies would have on the pulse arrival times (TOA's) and its timing residuals. Newer technology, like the PUPPI backend at Arecibo, allows for the exploration of an untouched planet parameter space. The project consisted of conducting precise timing using PUPPI, taking two hour long observations at 327 MHz, 430 MHz, and L-Band Wide (LBW) frequencies for 25 days. The data is processed in order to obtain standard profiles and TOA's that would be introduced into TEMPO2, allowing data point manipulation by fitting them for known pulsar parameters to acquire post fit residuals with expected precisions below 1 μs. The observations yielded residuals ranging between 0.40 μs and 1.89 μs for 430 MHz and 327 MHz, while LBW resulted in values higher than 4.0 μs, which is attributed to the many radio frequency interference (RFI) bands present in the data. Combining the newly and previously acquired data revealed a decrease in the dispersion measure (DM), from 10.16550 pc/cm3 to 10.15325 pc/cm3, since the pulsar was last observed, which allowed a correction for the effects of interstellar scintillation, which are most noticed at 327 MHz.

EIGHT γ-RAY PULSARS DISCOVERED IN BLIND FREQUENCY SEARCHES OF FERMI LAT DATA

International Nuclear Information System (INIS)

Saz Parkinson, P. M.; Dormody, M.; Ziegler, M.; Belfiore, A.; Johnson, R. P.; Ray, P. S.; Abdo, A. A.; Grove, J. E.; Gwon, C.; Ballet, J.; Baring, M. G.; Burnett, T. H.; Caliandro, G. A.; Camilo, F.; Caraveo, P. A.; De Luca, A.; Ferrara, E. C.; Harding, A. K.; Johnson, T. J.; Freire, P. C. C.

2010-01-01

We report the discovery of eight γ-ray pulsars in blind frequency searches of ∼650 source positions using the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. We present the timing models, light curves, and detailed spectral parameters of the new pulsars. PSRs J1023-5746, J1044-5737, J1413-5205, J1429-5911, and J1954+2836 are young (τ c 10 36 erg s -1 ), and located within the Galactic plane (|b| 0 ). The remaining three pulsars, PSRs J1846+0919, J1957+5033, and J2055+25, are less energetic, and located off the plane. Five pulsars are associated with sources included in the Fermi-LAT bright γ-ray source list, but only one, PSR J1413-6205, is clearly associated with an EGRET source. PSR J1023-5746 has the smallest characteristic age (τ c = 4.6 kyr) and is the most energetic ( E-dot = 1.1x10 37 erg s -1 ) of all γ-ray pulsars discovered so far in blind searches. By analyzing >100 ks of publicly available archival Chandra X-ray data, we have identified the likely counterpart of PSR J1023-5746 as a faint, highly absorbed source, CXOU J102302.8-574606. The large X-ray absorption indicates that this could be among the most distant γ-ray pulsars detected so far. PSR J1023-5746 is positionally coincident with the TeV source HESS J1023-575, located near the young stellar cluster Westerlund 2, while PSR J1954+2836 is coincident with a 4.3σ excess reported by Milagro at a median energy of 35 TeV. PSRs J1957+5033 and J2055+25 have the largest characteristic ages (τ c ∼ 1 Myr) and are the least energetic ( E-dot ∼5x10 33 erg s -1 ) of the newly discovered pulsars. We used recent XMM observations to identify the counterpart of PSR J2055+25 as XMMU J205549.4+253959. Deep radio follow-up observations of the eight pulsars resulted in no detections of pulsations and upper limits comparable to the faintest known radio pulsars, indicating that these pulsars can be included among the growing population of radio-quiet pulsars in our Galaxy being

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"

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

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

DISCOVERY OF FIVE NEW PULSARS IN ARCHIVAL DATA

International Nuclear Information System (INIS)

Mickaliger, M. B.; Collins, A.; Hough, L.; Tehrani, N.; Tenney, C.; Liska, A.; Swiggum, J.; Lorimer, D. R.; McLaughlin, M. A.; Boyles, J.

2012-01-01

Reprocessing of the Parkes Multibeam Pulsar Survey has resulted in the discovery of five previously unknown pulsars and several as-yet-unconfirmed candidates. PSR J0922–52 has a period of 9.68 ms and a dispersion measure (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 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. PSR J1546–59 has a period of 7.80 ms and a DM of 168.3 pc cm –3 . PSR J1725–3853 is an isolated 4.79 ms pulsar with a DM of 158.2 pc cm –3 . These pulsars were likely missed in earlier processing efforts due to the fact that they have both high DMs and short periods, and also due to the large number of candidates that needed to be looked through. These discoveries suggest that further pulsars are awaiting discovery in the multibeam survey data.

Listening in on Baby - Monitoring the Youngest Known Pulsar

Science.gov (United States)

Gotthelf, Eric

We have discovered a most remarkable young pulsar, PSR J1846-0258, in the core of a Crab-like pulsar wind nebula at the center of the bright shell-type SNR Kes 75. Based on its spin-down rate and X-ray spectrum, PSR J1846-0258 is likely the youngest known rotation-powered pulsar. Compared to the Crab pulsar, however, its period, spin-down rate, and X-ray conversion efficiency are each an order of magnitude greater, likely the result of its extreme magnetic field, above the quantum critical threshold. We propose to continue our monitoring campaign of PSR~J1846-0258 to measure the braking index, characterize its timing noise, and search for evidence of timing glitches. Furthermore, an X- ray ephemeris contemporal with GLAST is critical to detecting the pulsar at higher energies.

Monitoring Baby - Listening in on the Youngest Known Pulsar

Science.gov (United States)

Gotthelf, Eric

We have discovered a most remarkable young pulsar, PSR J1846-0258, in the core of a Crab-like pulsar wind nebula at the center of the bright shell-type supernova remnant Kes 75. Based on its spin-down rate and X- ray spectrum, PSR J1846-0258 is likely the youngest known rotation- powered pulsar. Compared to the Crab pulsar, however, its period, spin- down rate, and spin-down to X-ray luminosity conversion efficiency are each an order of magnitude greater, likely the result of its extreme magnetic field, above the quantum critical threshold. We propose to continue our monitoring campaign of PSR J1846-0258 to measure the braking index, characterize its timing noise, and search for evidence of glitches. This pulsar provides important insight into the evolution of the youngest NS-SNR systems.

The Emerging Population of Pulsar Wind Nebulae in Hard X-rays

Science.gov (United States)

Mattana, F.; Götz, D.; Terrier, R.; Renaud, M.; Falanga, M.

2009-05-01

The hard X-ray synchrotron emission from Pulsar Wind Nebulae probes energetic particles, closely related to the pulsar injection power at the present time. INTEGRAL has disclosed the yet poorly known population of hard X-ray pulsar/PWN systems. We summarize the properties of the class, with emphasys on the first hard X-ray bow-shock (CTB 80 powered by PSR B1951+32), and highlight some prospects for the study of Pulsar Wind Nebulae with the Simbol-X mission.

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.

The Green Bank Northern Celestial Cap Pulsar Survey. II. The Discovery and Timing of 10 Pulsars

Science.gov (United States)

Kawash, A. M.; McLaughlin, M. A.; Kaplan, D. L.; DeCesar, M. E.; Levin, L.; Lorimer, D. R.; Lynch, R. S.; Stovall, K.; Swiggum, J. K.; Fonseca, E.; Archibald, A. M.; Banaszak, S.; Biwer, C. M.; Boyles, J.; Cui, B.; Dartez, L. P.; Day, D.; Ernst, S.; Ford, A. J.; Flanigan, J.; Heatherly, S. A.; Hessels, J. W. T.; Hinojosa, J.; Jenet, F. A.; Karako-Argaman, C.; Kaspi, V. M.; Kondratiev, V. I.; Leake, S.; Lunsford, G.; Martinez, J. G.; Mata, A.; Matheny, T. D.; Mcewen, A. E.; Mingyar, M. G.; Orsini, A. L.; Ransom, S. M.; Roberts, M. S. E.; Rohr, M. D.; Siemens, X.; Spiewak, R.; Stairs, I. H.; van Leeuwen, J.; Walker, A. N.; Wells, B. L.

2018-04-01

We present timing solutions for 10 pulsars discovered in 350 MHz searches with the Green Bank Telescope. Nine of these were discovered in the Green Bank Northern Celestial Cap survey and one was discovered by students in the Pulsar Search Collaboratory program during an analysis of drift-scan data. Following the discovery and confirmation with the Green Bank Telescope, timing has yielded phase-connected solutions with high-precision measurements of rotational and astrometric parameters. Eight of the pulsars are slow and isolated, including PSR J0930‑2301, a pulsar with a nulling fraction lower limit of ∼30% and a nulling timescale of seconds to minutes. This pulsar also shows evidence of mode changing. The remaining two pulsars have undergone recycling, accreting material from binary companions, resulting in higher spin frequencies. PSR J0557‑2948 is an isolated, 44 ms pulsar that has been partially recycled and is likely a former member of a binary system that was disrupted by a second supernova. The paucity of such so-called “disrupted binary pulsars” (DRPs) compared to double neutron star (DNS) binaries can be used to test current evolutionary scenarios, especially the kicks imparted on the neutron stars in the second supernova. There is some evidence that DRPs have larger space velocities, which could explain their small numbers. PSR J1806+2819 is a 15 ms pulsar in a 44-day orbit with a low-mass white dwarf companion. We did not detect the companion in archival optical data, indicating that it must be older than 1200 Myr.

Possible contraction of the members of the binary pulsar PSR 1913+16 and its astrophysical consequences

International Nuclear Information System (INIS)

Spyrou, N.

1983-01-01

It is proposed that the small difference between the observed and the theoretically predicted decrease of the orbital period of the Binary Pulsar PSR 1913+16 is not due to the insufficiency of the quadrupole formula and can be attributed to a mass-energy loss due to the contraction of the binary's members. Assuming that the pair's primary is a typical, noncontracting pulsar, is in favour of a slowly contracting, neutron-star companion, thus limiting the member's radii to at most 25 km and 28 km, respectively. The primary's computed total absolute luminosity is in excellent agreement with the observed upper limit of its X-ray and optical luminosities. Moreover, the companion's slow contraction rate implies that its present total absolute luminosity presents a maximum at wavelengths characteristic of X-rays. Finally, it suggests that if the energy-loss remains constant, the duration of the contraction phase will be of the order of 10 8 y and the final radius about 25 km. (Auth.)

Listening in on Baby - Monitoring the Youngest Known Pulsar (core Program)

Science.gov (United States)

We have discovered a most remarkable young pulsar, PSR J1846-0258, in the core of a Crab-like pulsar wind nebula at the center of the bright shell-type SNR Kes 75. Based on its spin-down rate and X-ray spectrum, PSR J1846-0258 is likely the youngest known rotation-powered pulsar. Compared to the Crab pulsar, however, its period, spin-down rate, and X-ray conversion efficiency are each an order of magnitude greater, likely the result of its extreme magnetic field, above the quantum critical threshold. We propose to continue our monitoring campaign of PSR~J1846-0258 to measure the braking index, characterize its timing noise, and search for evidence of timing glitches. Furthermore, an X- ray ephemeris contemporal with GLAST is critical to detecting the pulsar at higher energies.

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

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...... and current multi-wavelength 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 30-1000 s and ingress and egress time-scales of 30-60 s. No change in hardness ratio was observed during the dips...

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.

Kepler K2 observations of the transitional millisecond pulsar PSR J1023+0038

Science.gov (United States)

Kennedy, M. R.; Clark, C. J.; Voisin, G.; Breton, R. P.

2018-06-01

For 80 d in 2017, the Kepler Space Telescope continuously observed the transitional millisecond pulsar system PSR J1023+0038 in its accreting state. We present analyses of the 59-s cadence data, focusing on investigations of the orbital light curve of the irradiated companion star and of flaring activity in the neutron star's accretion disc. The underlying orbital modulation from the companion star retains a similar amplitude and asymmetric heating profile as seen in previous photometric observations of the system in its radio pulsar state, suggesting that the heating mechanism has not been affected by the state change. We also find tentative evidence that this asymmetry may vary with time. The light curve also exhibits `flickering' activity, evident as short time-scale flux correlations throughout the observations, and periods of rapid mode-switching activity on time-scales shorter than the observation cadence. Finally, the system spent ˜ 20 per cent of the observations in a flaring state, with the length of these flares varying from <2 min up to several hours. The flaring behaviour is consistent with a self-organized criticality mechanism, most likely related to the build-up and release of mass at the inner edge of the accretion disc.

Discovery of a young, 267 millisecond pulsar in the supernova remnant W44

Science.gov (United States)

Wolszczan, A.; Cordes, J. M.; Dewey, R. J.

1991-01-01

This paper reports the discovery of a 267 msec pulsar, PSR 1853 + 01, in the SNR W44 (G34.7 - 0.4), located south of the W44, well within its radio shell and at the outher edge of the X-ray emission region which fills the SNR interior. The PSR 1853 + 01 is separated only 20 arcmin from the PSR 1854 + 00 pulsar discovered by Mohanty (1983). Results of timing observatons of PSR 1853 + 01 are presented, and a possible relationship between the two objects is examined. It is suggested that the two pulsars may have a common origin in a binary system disrupted by the explosion that produced W44.

MILLISECOND PULSAR SCINTILLATION STUDIES WITH LOFAR: INITIAL RESULTS

International Nuclear Information System (INIS)

Archibald, Anne M.; Kondratiev, Vladislav I.; Hessels, Jason W. T.; Stinebring, Daniel R.

2014-01-01

High-precision timing of millisecond pulsars (MSPs) over years to decades is a promising technique for direct detection of gravitational waves at nanohertz frequencies. Time-variable, multi-path scattering in the interstellar medium is a significant source of noise for this detector, particularly as timing precision approaches 10 ns or better for MSPs in the pulsar timing array. For many MSPs, the scattering delay above 1 GHz is at the limit of detectability; therefore, we study it at lower frequencies. Using the LOw-Frequency ARray (LOFAR) radio telescope, we have analyzed short (5-20 minutes) observations of 3 MSPs in order to estimate the scattering delay at 110-190 MHz, where the number of scintles is large and, hence, the statistical uncertainty in the scattering delay is small. We used cyclic spectroscopy, still relatively novel in radio astronomy, on baseband-sampled data to achieve unprecedented frequency resolution while retaining adequate pulse-phase resolution. We detected scintillation structure in the spectra of the MSPs PSR B1257+12, PSR J1810+1744, and PSR J2317+1439 with diffractive bandwidths of 6 ± 3, 2.0 ± 0.3, and ∼7 kHz, respectively, where the estimate for PSR J2317+1439 is reliable to about a factor of two. For the brightest of the three pulsars, PSR J1810+1744, we found that the diffractive bandwidth has a power-law behavior Δν d ∝ν α , where ν is the observing frequency and α = 4.5 ± 0.5, consistent with a Kolmogorov inhomogeneity spectrum. We conclude that this technique holds promise for monitoring the scattering delay of MSPs with LOFAR and other high-sensitivity, low-frequency arrays like the low-frequency component of the Square Kilometre Array

MILLISECOND PULSAR SCINTILLATION STUDIES WITH LOFAR: INITIAL RESULTS

Energy Technology Data Exchange (ETDEWEB)

Archibald, Anne M.; Kondratiev, Vladislav I.; Hessels, Jason W. T.; Stinebring, Daniel R., E-mail: archibald@astron.nl, E-mail: kondratiev@astron.nl, E-mail: hessels@astron.nl, E-mail: dan.stinebring@oberlin.edu [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990-AA Dwingeloo (Netherlands)

2014-08-01

High-precision timing of millisecond pulsars (MSPs) over years to decades is a promising technique for direct detection of gravitational waves at nanohertz frequencies. Time-variable, multi-path scattering in the interstellar medium is a significant source of noise for this detector, particularly as timing precision approaches 10 ns or better for MSPs in the pulsar timing array. For many MSPs, the scattering delay above 1 GHz is at the limit of detectability; therefore, we study it at lower frequencies. Using the LOw-Frequency ARray (LOFAR) radio telescope, we have analyzed short (5-20 minutes) observations of 3 MSPs in order to estimate the scattering delay at 110-190 MHz, where the number of scintles is large and, hence, the statistical uncertainty in the scattering delay is small. We used cyclic spectroscopy, still relatively novel in radio astronomy, on baseband-sampled data to achieve unprecedented frequency resolution while retaining adequate pulse-phase resolution. We detected scintillation structure in the spectra of the MSPs PSR B1257+12, PSR J1810+1744, and PSR J2317+1439 with diffractive bandwidths of 6 ± 3, 2.0 ± 0.3, and ∼7 kHz, respectively, where the estimate for PSR J2317+1439 is reliable to about a factor of two. For the brightest of the three pulsars, PSR J1810+1744, we found that the diffractive bandwidth has a power-law behavior Δν{sub d}∝ν{sup α}, where ν is the observing frequency and α = 4.5 ± 0.5, consistent with a Kolmogorov inhomogeneity spectrum. We conclude that this technique holds promise for monitoring the scattering delay of MSPs with LOFAR and other high-sensitivity, low-frequency arrays like the low-frequency component of the Square Kilometre Array.

NuSTAR OBSERVATIONS AND BROADBAND SPECTRAL ENERGY DISTRIBUTION MODELING OF THE MILLISECOND PULSAR BINARY PSR J1023+0038

Energy Technology Data Exchange (ETDEWEB)

Li, K. L.; Kong, A. K. H.; Tam, P. H. T.; Jin, Ruolan [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Takata, J.; Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Hui, C. Y., E-mail: lilirayhk@gmail.com, E-mail: akong@phys.nthu.edu.tw, E-mail: takata@hku.hk [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

2014-12-20

We report the first hard X-ray (3-79 keV) observations of the millisecond pulsar (MSP) binary PSR J1023+0038 using NuSTAR. This system has been shown transiting between a low-mass X-ray binary (LMXB) state and a rotation-powered MSP state. The NuSTAR observations were taken in both LMXB state and rotation-powered state. The source is clearly seen in both states up to ∼79 keV. During the LMXB state, the 3-79 keV flux is about a factor of 10 higher than in the rotation-powered state. The hard X-rays show clear orbital modulation during the X-ray faint rotation-powered state but the X-ray orbital period is not detected in the X-ray bright LMXB state. In addition, the X-ray spectrum changes from a flat power-law spectrum during the rotation-powered state to a steeper power-law spectrum in the LMXB state. We suggest that the hard X-rays are due to the intrabinary shock from the interaction between the pulsar wind and the injected material from the low-mass companion star. During the rotation-powered MSP state, the X-ray orbital modulation is due to Doppler boosting of the shocked pulsar wind. At the LMXB state, the evaporating matter of the accretion disk due to the gamma-ray irradiation from the pulsar stops almost all the pulsar wind, resulting in the disappearance of the X-ray orbital modulation.

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

International Nuclear Information System (INIS)

Schroeder, Joshua; Halpern, Jules

2014-01-01

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 NS > 1.75 M ☉ 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 c > 0.1 M ☉ ), 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.

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

Science.gov (United States)

Gvaramadze, Vasilii V.; Gualandris, Alessia; Portegies Zwart, Simon

2008-04-01

Recent proper motion and parallax measurements for the pulsar PSR B1508+55 indicate a transverse velocity of ~1100kms-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 velocity of the pulsar cannot have originated from the second supernova disruption of a massive binary system. The high velocity of PSR B1508+55 can be accounted for by assuming that it received a kick at birth or that the neutron star was accelerated after its formation in the supernova explosion. We propose an explanation for the origin of hyperfast neutron stars based on the hypothesis that they could be the remnants of a symmetric supernova explosion of a high-velocity massive star which attained its peculiar velocity (similar to that of the pulsar) in the course of a strong dynamical three- or four-body encounter in the core of dense young star cluster. To check this hypothesis, we investigated three dynamical processes involving close encounters between: (i) two hard massive binaries, (ii) a hard binary and an intermediate-mass black hole (IMBH) and (iii) a single stars and a hard binary IMBH. We find that main-sequence O-type stars cannot be ejected from young massive star clusters with peculiar velocities high enough to explain the origin of hyperfast neutron stars, but lower mass main-sequence stars or the stripped helium cores of massive stars could be accelerated to hypervelocities. Our explanation for the origin of hyperfast pulsars requires a very dense stellar environment of the order of 106- 107starspc-3. Although such high densities may exist during the core collapse of young massive star clusters, we caution that they have never been observed.

A Search for EGRET/Radio Pulsars in the ETA Carina Region

Science.gov (United States)

2002-01-01

Our analysis of EGRET data for the radio pulsar PSR B1046-58, which lies it the Eta Carina region of the Galaxy, was highly successful, resulting in the discovery of strong evidence for gamma-ray pulsations from this source. This work was published in the Astrophysical Journal. Additional support for the association was published in a companion paper in which an analysis of the X-ray counterpart to PSR B1046-58 was done, and we showed that it was the only possible counterpart to the gamma ray source within the EGRET error box.

Pulsar searching and timing with the Parkes telescope

Science.gov (United States)

Ng, C. W. Y.

2014-11-01

Pulsars are highly magnetised, rapidly rotating neutron stars that radiate a beam of coherent radio emission from their magnetic poles. An introduction to the pulsar phenomenology is presented in Chapter 1 of this thesis. The extreme conditions found in and around such compact objects make pulsars fantastic natural laboratories, as their strong gravitational fields provide exclusive insights to a rich variety of fundamental physics and astronomy. The discovery of pulsars is therefore a gateway to new science. An overview of the standard pulsar searching technique is described in Chapter 2, as well as a discussion on notable pulsar searching efforts undertaken thus far with various telescopes. The High Time Resolution Universe (HTRU) Pulsar Survey conducted with the 64-m Parkes radio telescope in Australia forms the bulk of this PhD. In particular, the author has led the search effort of the HTRU low-latitude Galactic plane project part which is introduced in Chapter 3. We discuss the computational challenges arising from the processing of the petabyte-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 the potential pulsar-black hole binaries. We show that under a linear acceleration approximation, a ratio of ~0.1 of data length over orbital period results in the highest effectiveness for this search algorithm. Chapter 4 presents the initial results from the HTRU low-latitude Galactic plane survey. From the 37 per cent of data processed thus far, we have re-detected 348 previously known pulsars and discovered a further 47 pulsars. Two of which are fast-spinning pulsars with periods less than 30 ms. PSR J1101-6424 is a millisecond pulsar (MSP) with a heavy white dwarf companion while its short spin period of 5 ms indicates

Discovery of a 50 millisecond pulsar in the Large Magellanic Cloud

Science.gov (United States)

Seward, F. D.; Harnden, F. R., Jr.; Helfand, D. J.

1984-01-01

The present investigation is concerned with the discovery of a new pulsed X-ray source in the Large Magellanic Cloud (LMC) supernova remnant 0540 - 693. The SNR 0540 - 693 is one of three suspected Crab-like remnants in the LMC. The existing X-ray, optical, and radio observations of the remnant itself are discussed, and an analysis is conducted of the implications of the period, period derivative, and X-ray pulse shape of the new source. It is concluded that the pulsed X-ray source is almost certainly a young, isolated pulsar. Many of its properties are very similar to those of the Crab pulsar.

PSR J1856+0245: Arecibo discovery of a young, energetic pulsar coincident with the TeV γ-ray source HESS J1857+026

NARCIS (Netherlands)

Hessels, J.W.T.; Nice, D.J.; Gaensler, B.M.; Kaspi, V.M.; Lorimer, D.R.; Champion, D.J.; Lyne, A.G.; Kramer, 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 81 ms, a characteristic age of 21 kyr, and a spin-down luminosity (E) over dot = 4.6 x 10(36) ergs s(-1). It is positionally coincident with the TeV gamma-ray source

Simultaneous broadband observations and high-resolution X-ray spectroscopy of the transitional millisecond pulsar PSR J1023+0038

Science.gov (United States)

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

2018-03-01

We report on the first simultaneous XMM-Newton, NuSTAR, and Swift observations of the transitional millisecond pulsar PSR J1023+0038 in the X-ray active state. Our multi-wavelength campaign allowed us to investigate with unprecedented detail possible spectral variability over a broad energy range in the X-rays, as well as correlations and lags among emissions in different bands. The soft and hard X-ray emissions are significantly correlated, with no lags between the two bands. On the other hand, the X-ray emission does not correlate with the UV emission. We refine our model for the observed mode switching in terms of rapid transitions between a weak propeller regime and a rotation-powered radio pulsar state, and report on a detailed high-resolution X-ray spectroscopy using all XMM-Newton Reflection Grating Spectrometer data acquired since 2013. We discuss our results in the context of the recent discoveries on the system and of the state of the art simulations on transitional millisecond pulsars, and show how the properties of the narrow emission lines in the soft X-ray spectrum are consistent with an origin within the accretion disc.

PULSED VERY HIGH ENERGY γ-RAY EMISSION CONSTRAINTS FOR PSR B1951+32 FROM STACEE OBSERVATIONS

International Nuclear Information System (INIS)

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

2009-01-01

The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a ground-based telescope that uses the wave-front-sampling technique to detect very high energy (VHE) gamma rays. STACEE's sensitivity in the energy range near 100 GeV permits useful observations of pulsars with the potential to discriminate between various proposed mechanisms for pulsed gamma-ray emission. Based on the 11.3 hr of data taken during the 2005 and 2006 observing seasons, we derive an upper limit on the pulsed gamma-ray emission from PSR B1951+32 of -11 photons cm -2 s -1 above an energy threshold of 117 GeV.

Evidence for free precession in a pulsar

Science.gov (United States)

Stairs; Lyne; Shemar

2000-08-03

Pulsars are rotating neutron stars that produce lighthouse-like beams of radio emission from their magnetic poles. The observed pulse of emission enables their rotation rates to be measured with great precision. For some young pulsars, this provides a means of studying the interior structure of neutron stars. Most pulsars have stable pulse shapes, and slow down steadily (for example, see ref. 20). Here we report the discovery of long-term, highly periodic and correlated variations in both the pulse shape and the rate of slow-down of the pulsar PSR B1828-11. The variations are best described as harmonically related sinusoids, with periods of approximately 1,000, 500 and 250 days, probably resulting from precession of the spin axis caused by an asymmetry in the shape of the pulsar. This is difficult to understand theoretically, because torque-free precession of a solitary pulsar should be damped out by the vortices in its superfluid interior.

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.

Monitoring Baby - Listening in on the Youngest Known Pulsar (XTEAO11)

Science.gov (United States)

Gotthelf, Eric

We have discovered a most remarkable young pulsar, PSR~J1846-0258, in the core of a Crab-like pulsar wind nebula at the center of the bright shell-type supernova remnant Kes~75. Based on its spin-down rate and X- ray spectrum, PSR~J1846-0258 is likely the youngest known rotation- powered pulsar. Compared to the Crab pulsar, however, its period, spin- down rate, and spin-down to X-ray luminosity conversion efficiency are each an order of magnitude greater, likely the result of its extreme magnetic field, above the quantum critical threshold. We propose to continue our monitoring campaign to measure the pulsar's braking index, characterize its timing noise, and search for evidence of timing glitches. This pulsar provides important insight into the evolution of the youngest NS-SNR systems.

Spectra of short-period pulsars according to the hypothesis of the two types of pulsars

International Nuclear Information System (INIS)

Malov, I.F.

1985-01-01

The lack of low-frequency turnovers in the spectra of PSR 0531+21 and 1937+21 may be expl ned if the generation of radio emission in these pulsars occurs near the light cylinder. Differences of high frequency cut-offs and spectral inoices for long-period pulsars and short-period ones are discussed

Discovery of an Energetic Pulsar Associated with SNR G76.9+1.0

Science.gov (United States)

Arzoumanian, Zaven; Gotthelf, E. V.; Ransom, S. M.; Safi-Harb, S.; Kothes, R.; Landecker, T. L.

2012-01-01

We report the discovery of PSR J2022-pulsar in the supernova remnant G76.9+i.0, in observations with the Chandra X-ray telescope, the Robert C. Byrd Green Bank Radio Telescope, and the Rossi X-ray Timing Explorer (RXTE). The pulsar's spin-down rate implies a rotation-powered luminosity E = 1.2 X 10(exp 38) erg/s, a surface dipole magnetic field strength B(sub S), = 1.0 X 10(exp 12) G, and a characteristic age of 8.9 kyr. PSR J2022+3842 is thus the second-most energetic Galactic pulsar known, after the Crab, as well as the most rapidly-rotating young, radio-bright pulsar known. The radio pulsations are highly dispersed and broadened by interstellar scattering, and we find that a large (delta f/f approximates 1.9 x 10(exp -6)) spin glitch must have occurred between our discovery and confirmation observations. The X-ray pulses are narrow (0.06 cycles FWHM) and visible up to 20 keV, consistent with magnetospheric emission from a rotation-powered pulsar. The Chandra X-ray image identifies the pulsar with a hard, unresolved source at the midpoint of the double-lobed radio morphology of G76.9+ 1.0 and embedded within faint, compact X-ray nebulosity. The spatial relationship of the X-ray and radio emissions is remarkably similar to extended structure seen around the Vela pulsar. The combined Chandra and RXTE pulsar spectrum is well-fitted by an absorbed power-law model with column density N(sub H) = (1.7 +/- 0.3) x 10(exp 22) / sq cm and photon index Gamma = 1.0 +/- 0.2; it implies that the Chandra point-source flux is virtually 100% pulsed. For a distance of 10 kpc, the X-ray luminosity of PSR J2022+3842 is L(sub x){2-1O keV) = 7.0 x 10(exp 33) erg/s. Despite being extraordinarily energetic, PSR J2022+3842 lacks a bright X-ray wind nebula and has an unusually low conversion efficiency of spin-down power to X-ray luminosity, Lx/E = 5.9 X 10(exp-5).

The Bursting Pulsar GRO J1744-28: the Slowest Transitional Pulsar?

Science.gov (United States)

Court, J. M. C.; Altamirano, D.; Sanna, A.

2018-04-01

GRO J1744-28 (the Bursting Pulsar) is a neutron star LMXB which shows highly structured X-ray variability near the end of its X-ray outbursts. In this letter we show that this variability is analogous to that seen in Transitional Millisecond Pulsars such as PSR J1023+0038: `missing link' systems consisting of a pulsar nearing the end of its recycling phase. As such, we show that the Bursting Pulsar may also be associated with this class of objects. We discuss the implications of this scenario; in particular, we discuss the fact that the Bursting Pulsar has a significantly higher spin period and magnetic field than any other known Transitional Pulsar. If the Bursting Pulsar is indeed transitional, then this source opens a new window of oppurtunity to test our understanding of these systems in an entirely unexplored physical regime.

The Discovery of the Most Accelerated Binary Pulsar

OpenAIRE

Cameron, A. D.; Champion, D. J.; Kramer, M.; Bailes, M.; Barr, E. D.; Bassa, C. G.; Bhandari, S.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; Eatough, R. P.; Flynn, C. M. L.; Freire, P. C. C.; Jameson, A.; Johnston, S.

2018-01-01

Pulsars in relativistic binary systems have emerged as fantastic natural laboratories for testing theories of gravity, the most prominent example being the double pulsar, PSR J0737$-$3039. The HTRU-South Low Latitude pulsar survey represents one of the most sensitive blind pulsar surveys taken of the southern Galactic plane to date, and its primary aim has been the discovery of new relativistic binary pulsars. Here we present our binary pulsar searching strategy and report on the survey's fla...

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.;

Old but Still Warm: Far-UV Detection of PSR B0950+08

Science.gov (United States)

Pavlov, G. G.; Rangelov, B.; Kargaltsev, O.; Reisenegger, A.; Guillot, S.; Reyes, C.

2017-11-01

We report on a Hubble Space Telescope detection of the nearby, old pulsar B0950+08 (d≃ 262 pc, spin-down age 17.5 Myr) in two far-ultraviolet (FUV) bands. We measured the mean flux densities {\\bar{f}}ν =109+/- 6 nJy and 83 ± 14 nJy in the F125LP and F140LP filters (pivot wavelengths 1438 and 1528 Å). Using the FUV data together with previously obtained optical-UV data, we conclude that the optical-FUV spectrum consists of two components—a nonthermal (presumably magnetospheric) power-law spectrum ({f}ν \\propto {ν }α ) with slope α ˜ -1.2 and a thermal spectrum emitted from the bulk of the neutron star (NS) surface with a temperature in the range of (1-3) × 105 K, depending on interstellar extinction and NS radius. These temperatures are much higher than predicted by NS cooling models for such an old pulsar, which means that some heating mechanisms operate in NSs. A plausible mechanism responsible for the high temperature of PSR B0950+08 is the interaction of vortex lines of the faster rotating neutron superfluid with the slower rotating normal matter in the inner NS crust (vortex creep heating). 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 program #13783.

LOFAR Discovery of the Fastest-spinning Millisecond Pulsar in the Galactic Field

Science.gov (United States)

Bassa, C. G.; Pleunis, Z.; Hessels, J. W. T.; Ferrara, E. C.; Breton, R. P.; Gusinskaia, N. V.; Kondratiev, V. I.; Sanidas, S.; Nieder, L.; Clark, C. J.; Li, T.; van Amesfoort, A. S.; Burnett, T. H.; Camilo, F.; Michelson, P. F.; Ransom, S. M.; Ray, P. S.; Wood, K.

2017-09-01

We report the discovery of PSR J0952-0607, a 707 Hz binary millisecond pulsar that is now the fastest-spinning neutron star known in the Galactic field (I.e., outside of a globular cluster). PSR J0952-0607 was found using LOFAR at a central observing frequency of 135 MHz, well below the 300 MHz to 3 GHz frequencies typically used in pulsar searches. The discovery is part of an ongoing LOFAR survey targeting unassociated Fermi-Large Area Telescope γ-ray sources. PSR J0952-0607 is in a 6.42 hr orbit around a very low-mass companion ({M}{{c}}≳ 0.02 {M}⊙ ), and we identify a strongly variable optical source, modulated at the orbital period of the pulsar, as the binary companion. The light curve of the companion varies by 1.6 mag from {r}{\\prime }=22.2 at maximum to {r}{\\prime }> 23.8, indicating that it is irradiated by the pulsar wind. Swift observations place a 3σ upper limit on the 0.3-10 {keV} X-ray luminosity of {L}Xdispersion measure). Though no eclipses of the radio pulsar are observed, the properties of the system classify it as a black widow binary. The radio pulsed spectrum of PSR J0952-0607, as determined through flux density measurements at 150 and 350 MHz, is extremely steep with α ˜ -3 (where S\\propto {ν }α ). We discuss the growing evidence that the fastest-spinning radio pulsars have exceptionally steep radio spectra, as well as the prospects for finding more sources like PSR J0952-0607.

THE GREEN BANK TELESCOPE 350 MHz DRIFT-SCAN SURVEY. I. SURVEY OBSERVATIONS AND THE DISCOVERY OF 13 PULSARS

Energy Technology Data Exchange (ETDEWEB)

Boyles, J.; Lorimer, D. R.; McLaughlin, M. A.; Cardoso, R. F. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Lynch, R. S.; Kaspi, V. M.; Archibald, A.; Karako-Argaman, C. [Department of Physics, McGill University, 3600 University St., Montreal, Quebec, H3A 2T8 (Canada); Ransom, S. M. [National Radio Astronomy Observatory (NRAO), 520 Edgemont Road, Charlottesville, VA 22901 (United States); Stairs, I. H.; Berndsen, A.; Cherry, A.; McPhee, C. A. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1 (Canada); Hessels, J. W. T.; Kondratiev, V. I.; Van Leeuwen, J. [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Epstein, C. R. [Department of Astronomy, Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210 (United States); Pennucci, T. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Roberts, M. S. E. [Eureka Scientific, 2452 Delmer Street, Suite 100, Oakland, CA 94602-3017 (United States); Stovall, K., E-mail: jason.boyles@wku.edu [Center for Advanced Radio Astronomy and Department of Physics and Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States)

2013-02-15

Over the summer of 2007, we obtained 1191 hr 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 13 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 dispersion measure (DM) of 27.9 pc cm{sup -3} in an 8.7 day orbit with a minimum companion mass of 0.22 M {sub Sun }. PSR J1737-0814 is a 4.2 ms pulsar at a DM of 55.3 pc cm{sup -3} in a 79.3 day orbit with a minimum companion mass of 0.06 M {sub Sun }. PSR J2222-0137 is a 32.8 ms pulsar at a very low DM of 3.27 pc cm{sup -3} in a 2.4 day orbit with a minimum companion mass of 1.11 M {sub Sun }. It is most likely a white-dwarf-neutron-star system or an unusual low-eccentricity double neutron star system. Ten other pulsars discovered in this survey are reported in the companion paper Lynch et al.

FERMI LARGE AREA TELESCOPE OBSERVATIONS OF PSR J1836+5925

International Nuclear Information System (INIS)

Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Belfiore, A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bonamente, E.; Brigida, M.

2010-01-01

The discovery of the γ-ray pulsar PSR J1836+5925, powering the formerly unidentified EGRET source 3EG J1835+5918, was one of the early accomplishments of the Fermi Large Area Telescope (LAT). Sitting 25 0 off the Galactic plane, PSR J1836+5925 is a 173 ms pulsar with a characteristic age of 1.8 million years, a spindown luminosity of 1.1 x 10 34 erg s -1 , and a large off-peak (OP) emission component, making it quite unusual among the known γ-ray pulsar population. We present an analysis of one year of LAT data, including an updated timing solution, detailed spectral results, and a long-term light curve showing no indication of variability. No evidence for a surrounding pulsar wind nebula is seen and the spectral characteristics of the OP emission indicate it is likely magnetospheric. Analysis of recent XMM-Newton observations of the X-ray counterpart yields a detailed characterization of its spectrum, which, like Geminga, is consistent with that of a neutron star showing evidence for both magnetospheric and thermal emission.

The Extended X-ray Nebula of PSR J1420-6048

Energy Technology Data Exchange (ETDEWEB)

Van Etten, Adam; Romani, Roger W.; /Stanford U., Phys. Dept.

2011-08-19

The vicinity of the unidentified EGRET source 3EG J1420-6038 has undergone extensive study in the search for counterparts, revealing the energetic young pulsar PSR J1420-6048 and its surrounding wind nebula as a likely candidate for at least part of the emission from this bright and extended gamma-ray source. We report on new Suzaku observations of PSR J1420-6048, along with analysis of archival XMM Newton data. The low background of Suzaku permits mapping of the extended X-ray nebula, indicating a tail stretching {approx} 8 minutes north of the pulsar. The X-ray data, along with archival radio and VHE data, hint at a pulsar birthsite to the North, and yield insights into its evolution and the properties of the ambient medium. We further explore such properties by modeling the spectral energy distribution (SED) of the extended nebula.

The Breakthrough Listen Search for Intelligent Life: Data Calibration using Pulsars

Science.gov (United States)

Brinkman-Traverse, Casey Lynn; Gajjar, Vishal; BSRC

2018-01-01

The ability to distinguish ET signals requires a deep understanding of the radio telescopes with which we search; therefore, before we observe stars of interest, the Breathrough Listen scientists at Berkeley SETI Research Center first observe a Pulsar with well-documented flux and polarization properties. The process of calibrating the flux and polarization is a lengthy process by hand, so we produced a pipeline code that will automatically calibrate the pulsar in under an hour. Using PSRCHIVE the code coherently dedisperses the pulsed radio signals, and then calibrates the flux using observation files with a noise diode turning on and off. The code was developed using PSR B1937+ 21 and is primarily used on PSR B0329+54. This will expedite the process of assessing the quality of data collected from the Green Bank Telescope in West Virginia and will allow us to more efficiently find life beyond Planet Earth. Additionally, the stability of the B0329+54 calibration data will allow us to analyze data taken on FRB's with confidence of its cosmic origin.

The green bank northern celestial cap pulsar survey. I. Survey description, data analysis, and initial results

Energy Technology Data Exchange (ETDEWEB)

Stovall, K.; Dartez, L. P.; Ford, A. J.; Garcia, A.; Hinojosa, J.; Jenet, F. A.; Leake, S. [Center for Advanced Radio Astronomy, University of Texas at Brownsville, One West University Boulevard, Brownsville, TX 78520 (United States); Lynch, R. S.; Archibald, A. M.; Karako-Argaman, C.; Kaspi, V. M. [Department of Physics, McGill University, 3600 University Street, Montreal, QC H3A 2T8 (Canada); Ransom, S. M. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22901 (United States); Banaszak, S.; Biwer, C. M.; Day, D.; Flanigan, J.; Kaplan, D. L. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Boyles, J. [Department of Physics and Astronomy, Western Kentucky University, Bowling Green, KY 42101 (United States); Hessels, J. W. T.; Kondratiev, V. I., E-mail: stovall.kevin@gmail.com [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo (Netherlands); and others

2014-08-10

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, at 350 MHz using the Green Bank Telescope. With the Green Bank Ultimate Pulsar Processing Instrument, we record 100 MHz of bandwidth divided into 4096 channels every 81.92 μs. This survey will cover the entire sky visible to the Green Bank Telescope (δ > –40°, or 82% of the sky) and outside of the Galactic Plane will be sensitive enough to detect slow pulsars and low dispersion measure (<30 pc cm{sup –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 and has an optical counterpart identified in archival data. PSR J0636+5129 is an MSP in a very short-period (96 minutes) orbit with a very low mass companion (8 M{sub J}). PSR J0645+5158 is an isolated MSP with a timing residual RMS of 500 ns and has been added to pulsar timing array experiments. PSR J1434+7257 is an isolated, intermediate-period pulsar that has been partially recycled. PSR J1816+4510 is an eclipsing MSP in a short-period orbit (8.7 hr) and may have recently completed its spin-up phase.

DISCOVERY OF NINE GAMMA-RAY PULSARS IN FERMI LARGE AREA TELESCOPE DATA USING A NEW BLIND SEARCH METHOD

Energy Technology Data Exchange (ETDEWEB)

Pletsch, H. J.; Allen, B.; Aulbert, C.; Fehrmann, H. [Albert-Einstein-Institut, Max-Planck-Institut fuer Gravitationsphysik, D-30167 Hannover (Germany); Guillemot, L.; Kramer, M.; Barr, E. D.; Champion, D. J.; Eatough, R. P.; Freire, P. C. C. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Ray, P. S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Belfiore, A.; Dormody, 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); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Caraveo, P. A. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Celik, Oe.; Ferrara, E. C. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Hessels, J. W. T. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Keith, M. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping NSW 1710 (Australia); Kerr, M., E-mail: holger.pletsch@aei.mpg.de, E-mail: guillemo@mpifr-bonn.mpg.de [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); and others

2012-01-10

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 J1803-2149 and J2111+ 4606, are young and energetic Galactic-plane pulsars (spin-down power above 6 Multiplication-Sign 10{sup 35} erg s{sup -1} and ages below 100 kyr). The seven remaining pulsars, PSRs J0106+4855, J0622+3749, J1620-4927, J1746-3239, J2028+3332, J2030+4415, and J2139+4716, are older and less energetic; two of them are located at higher Galactic latitudes (|b| > 10 Degree-Sign ). PSR J0106+4855 has the largest characteristic age (3 Myr) and the smallest surface magnetic field (2 Multiplication-Sign 10{sup 11} G) of all LAT blind-search pulsars. PSR J2139+4716 has the lowest spin-down power (3 Multiplication-Sign 10{sup 33} erg s{sup -1}) 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.

ASTROPHYSICAL PARAMETERS OF LS 2883 AND IMPLICATIONS FOR THE PSR B1259-63 GAMMA-RAY BINARY

International Nuclear Information System (INIS)

Negueruela, Ignacio; Lorenzo, Javier; Ribo, Marc; Herrero, Artemio; Khangulyan, Dmitry; Aharonian, Felix A.

2011-01-01

Only a few binary systems with compact objects display TeV emission. The physical properties of the companion stars represent basic input for understanding the physical mechanisms behind the particle acceleration, emission, and absorption processes in these so-called gamma-ray binaries. Here we present high-resolution and high signal-to-noise optical spectra of LS 2883, the Be star forming a gamma-ray binary with the young non-accreting pulsar PSR B1259-63, showing it to rotate faster and be significantly earlier and more luminous than previously thought. Analysis of the interstellar lines suggests that the system is located at the same distance as (and thus is likely a member of) Cen OB1. Taking the distance to the association, d = 2.3 kpc, and a color excess of E(B - V) = 0.85 for LS 2883 results in M V ∼ -4.4. Because of fast rotation, LS 2883 is oblate (R eq ≅ 9.7 R sun and R pole ≅ 8.1 R sun ) and presents a temperature gradient (T eq ∼ 27,500 K, log g eq = 3.7; T pole ∼ 34,000 K, log g pole = 4.1). If the star did not rotate, it would have parameters corresponding to a late O-type star. We estimate its luminosity at log(L * /L sun ) ≅ 4.79 and its mass at M * ∼ 30 M sun . The mass function then implies an inclination of the binary system i orb ∼ 23 0 , slightly smaller than previous estimates. We discuss the implications of these new astrophysical parameters of LS 2883 for the production of high-energy and very high-energy gamma rays in the PSR B1259-63/LS 2883 gamma-ray binary system. In particular, the stellar properties are very important for prediction of the line-like bulk Comptonization component from the unshocked ultrarelativistic pulsar wind.

Binary and Millisecond Pulsars.

Science.gov (United States)

Lorimer, Duncan R

2008-01-01

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 1.5 M ⊙ , 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. Supplementary material is available for this article at 10.12942/lrr-2008-8.

The SUrvey for Pulsars and Extragalactic Radio Bursts - I. Survey description and overview

Science.gov (United States)

Keane, E. F.; Barr, E. D.; Jameson, A.; Morello, V.; Caleb, M.; Bhandari, S.; Petroff, E.; Possenti, A.; Burgay, M.; Tiburzi, C.; Bailes, M.; Bhat, N. D. R.; Burke-Spolaor, S.; Eatough, R. P.; Flynn, C.; Jankowski, F.; Johnston, S.; Kramer, M.; Levin, L.; Ng, C.; van Straten, W.; Krishnan, V. Venkatraman

2018-01-01

We describe the Survey for Pulsars and Extragalactic Radio Bursts (SUPERB), an ongoing pulsar and fast transient survey using the Parkes radio telescope. SUPERB involves real-time acceleration searches for pulsars and single-pulse searches for pulsars and fast radio bursts. We report on the observational set-up, data analysis, multiwavelength/messenger connections, survey sensitivities to pulsars and fast radio bursts and the impact of radio frequency interference. We further report on the first 10 pulsars discovered in the project. Among these is PSR J1306-40, a millisecond pulsar in a binary system where it appears to be eclipsed for a large fraction of the orbit. PSR J1421-4407 is another binary millisecond pulsar; its orbital period is 30.7 d. This orbital period is in a range where only highly eccentric binaries are known, and expected by theory; despite this its orbit has an eccentricity of 10-5.

PULSE INTENSITY MODULATION AND THE TIMING STABILITY OF MILLISECOND PULSARS: A CASE STUDY OF PSR J1713+0747

Energy Technology Data Exchange (ETDEWEB)

Shannon, Ryan M. [CSIRO Astronomy and Space Science, Box 76, Epping, NSW 1710 (Australia); Cordes, James M., E-mail: ryan.shannon@csiro.au, E-mail: cordes@astro.cornell.edu [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States)

2012-12-10

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 (TOA) variations are correlated across a wide frequency range and is 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 Almost-Equal-To 40 {mu}s, 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 completely consistent with arrival time variations of pulse profiles obtained by integrating N pulses such that the arrival-time error decreases proportional to 1/{radical}N. We investigate methods for correcting TOAs for these pulse-shape changes, including multi-component TOA fitting and principal component analysis. These techniques are not found to improve the timing precision of the observations. We conclude that when pulse-shape changes dominate timing errors, the timing precision of PSR J1713+0747 can be only improved by averaging over a larger number of pulses.

Constraining the gravitational binding energy of PSR J0737-3039B using terrestrial nuclear data

International Nuclear Information System (INIS)

Newton, W. G.; Li Baoan

2009-01-01

We show that the gravitational binding energy of a neutron star of a given mass is correlated with the slope of the nuclear symmetry energy at 1-2 times nuclear saturation density for equations of state without significant softening (i.e., those that predict maximum masses M max >1.44M · in line with the largest accurately measured neutron star mass). Applying recent laboratory constraints on the slope of the symmetry energy to this correlation we extract a constraint on the baryon mass of the lower mass member of the double pulsar binary system, PSR J0737-3039B. We compare with independent constraints derived from modeling the progenitor star of J0737-3039B up to and through its collapse under the assumption that it formed in an electron capture supernova. The two sets of constraints are consistent only if L < or approx. 70 MeV.

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

Indian Academy of Sciences (India)

Sandro Mereghetti

2017-09-12

Sep 12, 2017 ... discovery of X-ray variability anti-correlated with the pulsar radio intensity ... a single power law, thus ruling out the interpretation of. Hermsen et al. ..... and a detailed knowledge of its complex phenomenol- ogy. Thanks to the ...

Radio emission region exposed: courtesy of the double pulsar

Science.gov (United States)

Lomiashvili, David; Lyutikov, Maxim

2014-06-01

The double pulsar system PSR J0737-3039A/B offers exceptional possibilities for detailed probes of the structure of the pulsar magnetosphere, pulsar winds and relativistic reconnection. We numerically model the distortions of the magnetosphere of pulsar B by the magnetized wind from pulsar A, including effects of magnetic reconnection and of the geodetic precession. Geodetic precession leads to secular evolution of the geometric parameters and effectively allows a 3D view of the magnetosphere. Using the two complimentary models of pulsar B's magnetosphere, adapted from the Earth's magnetosphere models by Tsyganenko (ideal pressure confinement) and Dungey (highly resistive limit), we determine the precise location and shape of the coherent radio emission generation region within pulsar B's magnetosphere. We successfully reproduce orbital variations and secular evolution of the profile of B, as well as subpulse drift (due to reconnection between the magnetospheric and wind magnetic fields), and determine the location and the shape of the emission region. The emission region is located at about 3750 stellar radii and has a horseshoe-like shape, which is centred on the polar magnetic field lines. The best-fitting angular parameters of the emission region indicate that radio emission is generated on the field lines which, according to the theoretical models, originate close to the poles and carry the maximum current. We resolved all but one degeneracy in pulsar B's geometry. When considered together, the results of the two models converge and can explain why the modulation of B's radio emission at A's period is observed only within a certain orbital phase region. Our results imply that the wind of pulsar A has a striped structure only 1000 light-cylinder radii away. We discuss the implications of these results for pulsar magnetospheric models, mechanisms of coherent radio emission generation and reconnection rates in relativistic plasma.

Detection of VHE gamma-ray emission from the vicinity of PSR B1706-44 with H.E.S.S.

Energy Technology Data Exchange (ETDEWEB)

Chaves, Ryan C.G.; Ona Wilhelmi, Emma de [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Terrier, Regis [APC, CNRS, Univ. Paris-7 (France); Stegmann, Christian [Universitaet Erlangen-Nuernberg, Erlangen (Germany). Physikalisches Institut; Khelifi, Bruno [LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau (France); Jager, Okkie C. de [Unit for Space Physics, North-West Univ., Potchefstroom (South Africa)

2010-07-01

The gamma-ray pulsar PSR B1706-44 and the adjacent supernova remnant (SNR) candidate G343.1-2.3 were observed by H.E.S.S. during a dedicated observational campaign in 2007. A new source of very-high-energy (VHE;E>100 GeV) gamma-ray emission, HESS J1708-443, was discovered with its centroid at RA(J2000.0)=17 h 8 m 10 s and Dec (J2000.0)=-44 d 21{sup '} ({+-}3{sup '} statistical error on each axis). The VHE gamma-ray source is significantly more extended than the H.E.S.S. point-spread function and has an intrinsic Gaussian width of 0.29 {+-}0.04 . Its energy spectrum can be described by a power law with a photon index=2.0{+-}0.1 (stat){+-}0.2 (syst). The integral flux measured between 1 and 10 TeV is {proportional_to}17% of the Crab Nebula flux in the same energy range. The possible associations with the energetic PSR B1706-44, also recently detected in the GeV domain with Fermi/LAT and AGILE, and SNR G343.1-2.3 are discussed.

DO RADIO MAGNETARS PSR J1550-5418 AND J1622-4950 HAVE GIGAHERTZ-PEAKED SPECTRA?

Energy Technology Data Exchange (ETDEWEB)

Kijak, J.; Tarczewski, L.; Lewandowski, W. [Kepler Institute of Astronomy, University of Zielona Gora, Lubuska 2, 65-265 Zielona Gora (Poland); Melikidze, G., E-mail: jkijak@astro.ia.uz.zgora.pl [Also at Abastumani Astrophysical Observatory, Ilia State University, 3-5 Cholokashvili Avenue, Tbilisi 0160, Georgia. (Georgia)

2013-07-20

We study the radio spectra of two magnetars, PSR J1550-5418 and J1622-4950. We argue that they are good candidates for pulsars with gigahertz-peaked spectra (GPS), as their observed flux density decreases at frequencies below 7 GHz. We suggest that this behavior is due to the influence of the pulsars' environments on radio waves. Both of the magnetars are associated with supernova remnants and thus are surrounded by hot, ionized gas, which can be responsible for the free-free absorption of radio waves. We conclude that the GPS feature of both magnetars and typical pulsars are formed by similar processes in the surrounding media rather than by different radio-emission mechanisms. Thus, the radio magnetars PSR J1550-5418 and J1622-4950 can be included in the class of GPS pulsars.

Gamma rays from pulsar outer gaps

International Nuclear Information System (INIS)

Chiang, J.; Romani, R.W.; Cheng Ho

1993-01-01

We describe a gamma ray pulsar code which computes the high energy photon emissivities from vacuum gaps in the outer magnetosphere, after the model outlined by Cheng, Ho and Ruderman (1986) and Ho (1989). Pair-production due to photon-photon interactions and radiation processes including curvature, synchrotron and inverse Compton processes are computed with an iterative scheme which converges to self-consistent photon and particle distributions for a sampling of locations in the outer magnetosphere. We follow the photons from these distributions as they propagate through the pulsar magnetosphere toward a distant observer. We include the effects of relativistic aberration, time-of-flight delays and reabsorption by photon-photon pair-production to determine an intensity map of the high energy pulsar emission on the sky. Using data from radio and optical observations to constrain the geometry of the magnetosphere as well as the possible observer viewing angles, we derive light curves and phase dependent spectra which can be directly compared to data from the Compton Observatory. Observations for Crab, Vela and the recently identified gamma ray pulsars Geminga, PSR1706-44 aNd PSR 1509-58 will provide important tests of our model calculations, help us to improve our picture of the relevant physics at work in pulsar magnetospheres and allow us to comment on the implications for future pulsar discoveries

A BROADBAND RADIO STUDY OF THE AVERAGE PROFILE AND GIANT PULSES FROM PSR B1821-24A

Energy Technology Data Exchange (ETDEWEB)

Bilous, A. V. [Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen (Netherlands); Pennucci, T. T. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Demorest, P. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Ransom, S. M., E-mail: a.bilous@science.ru.nl [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

2015-04-20

We present the results of a wideband (720–2400 MHz) study of PSR B1821–24A (J1824–2452A, M28A), an energetic millisecond pulsar (MSP) visible in radio, X-rays and γ-rays. In radio, the pulsar has a complex average profile that 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 synthesize our findings with high-energy information to compare M28A to other known γ-ray MSPs 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 a handful of pulsars that are known to emit giant radio pulses (GRPs)—short, bright radio pulses of unknown nature. We report a drop in the linear polarization of the average profile in both windows of GRP generation and also a “W”-shaped absorption feature (resembling a double notch), partly overlapping with one of the GRP windows. The GRPs themselves have broadband spectra consisting of multiple patches with Δν/ν ∼ 0.07. Although our time resolution was not sufficient to resolve the GRP structure on the μs scale, we argue that GRPs from this pulsar most closely resemble the GRPs from the main pulse of the Crab pulsar, which consist of a series of narrowband nanoshots.

POST-OUTBURST RADIO OBSERVATIONS OF THE HIGH MAGNETIC FIELD PULSAR PSR J1119-6127

Energy Technology Data Exchange (ETDEWEB)

Majid, Walid A.; Pearlman, Aaron B.; Dobreva, Tatyana; Kocz, Jonathon; Prince, Thomas A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Horiuchi, Shinji [CSIRO Astronomy and Space Science, Canberra Deep Space Communications Complex, P.O. Box 1035, Tuggeranong, ACT 2901 (Australia); Lippuner, Jonas [TAPIR, Walter Burke Institute for Theoretical Physics, MC 350-17, California Institute of Technology, Pasadena, CA 91125 (United States)

2017-01-01

We have carried out high-frequency radio observations of the high magnetic field pulsar PSR J1119-6127 following its recent X-ray outburst. While initial observations showed no evidence of significant radio emission, subsequent observations detected pulsed emission across a large frequency band. In this Letter, we report on the initial disappearance of the pulsed emission and its prompt reactivation and dramatic evolution over several months of observation. The periodic pulse profile at S -band (2.3 GHz) after reactivation exhibits a multi-component emission structure, while the simultaneous X -band (8.4 GHz) profile shows a single emission peak. Single pulses were also detected at S -band near the main emission peaks. We present measurements of the spectral index across a wide frequency bandwidth, which captures the underlying changes in the radio emission profile of the neutron star. The high-frequency radio detection, unusual emission profile, and observed variability suggest similarities with magnetars, which may independently link the high-energy outbursts to magnetar-like behavior.

PSR B 1706-44 and the SNR G 343.1-2.3 as the remnants of a cavity supernova explosion

Science.gov (United States)

Bock, D. C.-J.; Gvaramadze, V. V.

2002-11-01

The possible association of the supernova remnant (SNR) G 343.1-2.3 with the pulsar PSR B 1706-44 (superposed on the arclike ``shell" of the SNR) has been questioned by some authors on the basis of an inconsistency between the implied and measured (scintillation) transverse velocities of the pulsar, the absence of any apparent interaction between the pulsar and the SNR's ``shell'', and some other indirect arguments. We suggest, however, that this association could be real if both objects are the remnants of a supernova (SN) which exploded within a mushroom-like cavity (created by the SN progenitor wind breaking out of the parent molecular cloud). This suggestion implies that the actual shape of the SNR's shell is similar to that of the well-known SNR VRO 42.05.01 and that the observed bright arc corresponds to the ``half'' of the SNR located inside the cloud. We report the discovery in archival radio data of an extended ragged radio arc to the southeast of the bright arc which we interpret as the ``half'' of the SN blast wave expanding in the intercloud medium.

Optical Observations of Psr J2021+3651 in the Dragonfly Nebula With the GTC

Science.gov (United States)

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

2015-03-01

PSR J2021+3651 is a 17 kyr old rotation powered pulsar detected in the radio, X-rays, and γ-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 Gran Telescopio Canarias in the Sloan r‧ band to search for optical counterparts of the pulsar and its nebula. No counterparts were detected down to r‧ ≳ 27.2 and ≳24.8 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=1.8-1.4+1.7 kpc at 90% confidence. It is much smaller than the dispersion measure distance of ˜12 kpc but compatible with a γ-ray “pseudo-distance” of 1 kpc. Based on that and the optical upper limits, we conclude that PSR J2021+3651, similar to the Vela pulsar, is a very inefficient nonthermal emitter in the optical and X-rays, while its γ-ray efficiency is consistent with an average efficiency for γ-pulsars of similar age. Our optical flux upper limit for the pulsar is consistent with the long-wavelength extrapolation of its X-ray spectrum while the nebula flux upper limit does not constrain the respective extrapolation. Based on observations made with the Gran Telescopio Canarias (GTC), instaled in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofsica de Canarias, in the island of La Palma, programme GTC3-11B.

Reconciling Optical and Radio Observations of the Binary Millisecond Pulsar PSR J1640+2224

Science.gov (United States)

Vigeland, Sarah J.; Deller, Adam T.; Kaplan, David L.; Istrate, Alina G.; Stappers, Benjamin W.; Tauris, Thomas M.

2018-03-01

Previous optical and radio observations of the binary millisecond pulsar PSR J1640+2224 have come to inconsistent conclusions about the identity of its companion, with some observations suggesting that the companion is a low-mass helium-core (He-core) white dwarf (WD), while others indicate that it is most likely a high-mass carbon–oxygen (CO) WD. Binary evolution models predict PSR J1640+2224 most likely formed in a low-mass X-ray binary based on the pulsar’s short spin period and long-period, low-eccentricity orbit, in which case its companion should be a He-core WD with mass about 0.35–0.39 M ⊙, depending on metallicity. If instead it is a CO WD, it would suggest that the system has an unusual formation history. In this paper we present the first astrometric parallax measurement for this system from observations made with the Very Long Baseline Array (VLBA), from which we determine the distance to be {1520}-150+170 {pc}. We use this distance and a reanalysis of archival optical observations originally taken in 1995 with the Wide Field Planetary Camera 2 on the Hubble Space Telescope (HST) to measure the WD’s mass. We also incorporate improvements in calibration, extinction model, and WD cooling models. We find that the existing observations are not sufficient to tightly constrain the companion mass, but we conclude the WD mass is >0.4 M ⊙ with >90% confidence. The limiting factor in our analysis is the low signal-to-noise ratio of the original HST observations.

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

2010-09-10

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.

Early NICER Observations of Magnetars and Young Pulsars

Science.gov (United States)

Nynka, Melania

2018-01-01

Neutron star Interior Composition ExploreR (NICER) is an X-ray telescope attached to the International Space Station (ISS). Launched in June 2017, it is designed to precisely measure the masses and radii of neutron stars (NS) and probe NS equations of state. But its precision timing capabilities and large effective area uniquely position NICER for the study of magnetars. The NICER Magnetar & Magnetosphere (M&M) science working group focuses on studying highly-magnetized neutron stars, a diverse program that includes magnetars, high-B pulsars, rotation powered pulsars, and isolated neutron stars. Our ongoing campaign has already observed targets such as 4U 0142+61, a magnetar in outburst with coincident NuSTAR and Swift observations, the radio rotation powered Vela pulsar PSR B0833-45, and a transient magnetar XTE J1810-197. I will discuss the goals of the M&M program, spectral and temporal results from the observed targets, and an overview of upcoming observations.

Gamma–Gamma Absorption in the γ-ray Binary System PSR B1259-63/LS 2883

Energy Technology Data Exchange (ETDEWEB)

Sushch, Iurii [Centre for Space Research, North-West University, 2520 Potcheftroom (South Africa); Van Soelen, Brian, E-mail: iurii.sushch@desy.de, E-mail: vansoelenb@ufs.ac.za [Department of Physics, University of the Free State, 9300 Bloemfontein (South Africa)

2017-03-10

The observed TeV light curve from the γ -ray binary PSR B1259-63/LS 2883 shows a decrease in the flux at periastron that has not been fully explained by emission mechanisms alone. This observed decrease can, however, be explained by γγ absorption due to the stellar and disk photons. We calculate the γγ absorption in PSR B1259-63/LS 2883 taking into account photons from both the circumstellar disk and star, assuming that the γ -rays originate at the position of the pulsar. The γγ absorption due to the circumstellar disk photons produces a ≈14% decrease in the flux, and there is a total decrease of ≈52% (>1 TeV) within a few days before periastron, accompanied by a hardening of the γ -ray photon index. While the γγ absorption alone is not sufficient to explain the full complexity of the H.E.S.S. γ -ray light curve, it results in a significant decrease in the predicted flux, which is coincident with the observed decrease. In addition, we have calculated an upper limit on the γγ absorption, assuming that the emission is produced at the apex of the bow shock. Future observations with CTA during the 2021 periastron passage may be able to confine the location of the emission based on the degree of γγ absorption, as well as measure the hardening of the spectrum around periastron.

Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

OpenAIRE

Abeysekara, A. U.; Albert, A.; Alfaro, R.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Rojas, D. Avila; Solares, H. A. Ayala; Barber, A. S.; Bautista-Elivar, N.; Becerril, A.; Belmont-Moreno, E.; BenZvi, S. Y.; Berley, D.

2017-01-01

The unexpectedly high flux of cosmic ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the HighAltitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of ac...

THE MASSIVE PULSAR PSR J1614-2230: LINKING QUANTUM CHROMODYNAMICS, GAMMA-RAY BURSTS, AND GRAVITATIONAL WAVE ASTRONOMY

International Nuclear Information System (INIS)

Oezel, 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 (GRBs), and the generation of gravitational waves from coalescing neutron stars. This single high-mass value indicates that a transition to quark matter in neutron-star cores can occur at densities comparable to the nuclear saturation density only if the quarks are strongly interacting and are color superconducting. We further show that a high maximum neutron-star mass is required if short-duration GRBs are powered by coalescing neutron stars and, therefore, this mechanism becomes viable in the light of the recent measurement. Finally, we argue that the low-frequency (≤500 Hz) gravitational waves emitted during the final stages of neutron-star coalescence encode the properties of the equation of state because neutron stars consistent with this measurement cannot be centrally condensed. This will facilitate the measurement of the neutron star equation of state with Advanced LIGO/Virgo.

A millisecond pulsar in a stellar triple system.

Science.gov (United States)

Ransom, S M; Stairs, I H; 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

2014-01-23

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, PSR B1620-26 (refs 7, 8; 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 multiwavelength 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 M[Symbol: see text](1.4378(13), where M[Symbol: see text]is the solar mass and the parentheses contain the uncertainty in the final decimal places) and the two white dwarf companions (0.19751(15)M[Symbol: see text] and 0.4101(3))M[Symbol: see text], as well as the inclinations of the orbits (both about 39.2°). The unexpectedly coplanar and nearly circular orbits indicate a complex and exotic evolutionary past that differs from those of known stellar systems. The gravitational field of the outer white dwarf strongly accelerates the inner binary containing the neutron star, and the system will thus provide an ideal laboratory in which to test the strong equivalence principle of general relativity.

Binary system containing the pulsar PSR 1913 + 16 and ultra-violet and x-radiation from accreting magnetic white dwarfs

International Nuclear Information System (INIS)

Masters, A.R.

1978-01-01

Part I of the thesis deals with the binary system containing the pulsar PSR 1913 + 16. The system has been touted as a laboratory for testing relativistic theories of gravity, and is also a challenge for theories of stellar evolution. However, proposed uses of the system rely on assumptions about the nature of the pulsar's unobserved companion. Ways of determining the nature of the companion from observation of the pulsar are discussed. Geometrical constraints on the size of the pulsar's orbit and the observed slow rate of the orbit's precession require that the companion be a black hole, a neutron star, a white dwarf or a helium main-sequence star. Observable second-order relativistic effects may or may not further restrict the list of candidates. The discussion summarizes Masters and Roberts, 1975 Ap.J. (Letters), 195, L107, and Roberts, Masters and Arnett, 1976, Ap. J., 203, 196. Part II of the thesis treats ultra-violet and X-radiation from accreting magnetic white dwarfs. Matter from a companion star falling onto a white dwarf is shock-heated near the stellar surface and radiatively cooled. The post-shock region is approximated by a uniform, geometrically thin slab and determine the physical conditions behind the shock and the emitted spectrum for a range of stellar masses, magnetic fields and accretion rates. At low magnetic fields and high accretion rates, bremsstrahlung is the dominant cooling mechanism and the post-shock material is a single fluid (the electrons and ions have a common temperature). As the magnetic field increases or the accretion rate decreases, cyclotron emission becomes more important than bremsstrahlung

A 110-ms pulsar, with negative period derivative, in the global cluster M15

International Nuclear Information System (INIS)

Wolszczan, A.; Kulkarni, S.R.; Middleditch, J.; Backer, D.C.; Fruchter, A.S.; Dewey, R.J.

1989-01-01

We report the discovery of a 110-ms pulsar, PSR2127 + 11, in the globular cluster M15 (NGC7078). The results of nine months of timing measurements place the new pulsar about 2'' from the centre of the cluster, and indicate that it is not a member of a close binary system. The measured negative value of the period derivative, P ∼-2 x 10 -17 s s -1 , is probably the result of the pulsar being bodily accelerated in our direction by the gravitational field of the collapsed core of M15. Although PSR2127 + 11 has an unexpectedly long period, we argue that it belongs to the class of 'recycled' pulsars, which have been spun up by accretion in a binary system. (author)

Chandra Phase-resolved Spectroscopy of the High Magnetic Field Pulsar B1509−58

Energy Technology Data Exchange (ETDEWEB)

Hu, Chin-Ping; Ng, C.-Y. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Takata, J. [School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei (China); Shannon, R. M. [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia); Johnston, S., E-mail: cphu@hku.hk, E-mail: ncy@bohr.physics.hku.hk [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Box 76, Epping, NSW 1710 (Australia)

2017-04-01

We report on a timing and spectral analysis of the young, high magnetic field rotation-powered pulsar (RPP) B1509−58 using Chandra continuous-clocking mode observation. The pulsar’s X-ray light curve can be fit by the two Gaussian components and the pulsed fraction shows moderate energy dependence over the Chandra band. The pulsed X-ray spectrum is well described by a power law with a photon index 1.16(4), which is harder than the values measured with RXTE /PCA and NuSTAR . This result supports the log-parabolic model for the broadband X-ray spectrum. With the unprecedented angular resolution of Chandra , we clearly identified off-pulse X-ray emission from the pulsar, and its spectrum is best fit by a power law plus blackbody model. The latter component has a temperature of ∼0.14 keV with a bolometric luminosity comparable to the luminosities of other young and high magnetic field RPPs, and it lies between the temperature of magnetars and typical RPPs. In addition, we found that the nonthermal X-ray emission of PSR B1509−58 is significantly softer in the off-pulse phase than in the pulsed phase, with the photon index varying between 1.0 and 1.8 and anticorrelated with the flux. This is similar to the behavior of three other young pulsars. We interpreted it as different contributions of pair-creation processes at different altitudes from the neutron star surface according to the outer-gap model.

High precision pulsar timing and spin frequency second derivatives

Science.gov (United States)

Liu, X. J.; Bassa, C. G.; Stappers, B. W.

2018-05-01

We investigate the impact of intrinsic, kinematic and gravitational effects on high precision pulsar timing. We present an analytical derivation and a numerical computation of the impact of these effects on the first and second derivative of the pulsar spin frequency. In addition, in the presence of white noise, we derive an expression to determine the expected measurement uncertainty of a second derivative of the spin frequency for a given timing precision, observing cadence and timing baseline and find that it strongly depends on the latter (∝t-7/2). We show that for pulsars with significant proper motion, the spin frequency second derivative is dominated by a term dependent on the radial velocity of the pulsar. Considering the data sets from three Pulsar Timing Arrays, we find that for PSR J0437-4715 a detectable spin frequency second derivative will be present if the absolute value of the radial velocity exceeds 33 km s-1. Similarly, at the current timing precision and cadence, continued timing observations of PSR J1909-3744 for about another eleven years, will allow the measurement of its frequency second derivative and determine the radial velocity with an accuracy better than 14 km s-1. With the ever increasing timing precision and observing baselines, the impact of the, largely unknown, radial velocities of pulsars on high precision pulsar timing can not be neglected.

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.

Radio search for pulsed emission from X-ray pulsars

Energy Technology Data Exchange (ETDEWEB)

delli Santi, F S; Delpino, F [Bologna Univ. (Italy). Ist. di Astronomia; Inzani, P; Sironi, G [Consiglio Nazionale delle Ricerche, Milan (Italy). Lab. di Fisica Cosmica e Tecnologie Relative; Mandolesi, N; Morigi, G [Consiglio Nazionale delle Ricerche, Bologna (Italy). Lab. TESRE

1981-05-01

An experiment has been performed at 325 MHz, with a 10 m tracking dish, for the search of pulsed radio emission associated with X-ray pulsars. No evidence of radio pulses has been found in the four sources investigated, although the radio pulsar PSR 0329 + 54, used a testing object, has been detected successfully.

LONG-TERM MONITORING OF MODE SWITCHING FOR PSR B0329+54

International Nuclear Information System (INIS)

Chen, J. L.; Wang, N.; Liu, Z. Y.; Yuan, J. P.; Wang, H. G.; Lyne, A.; Jessner, A.; Kramer, M.

2011-01-01

The mode-switching phenomenon of PSR B0329+54 is investigated based on the long-term monitoring from 2003 September to 2009 April made with the Urumqi 25 m radio telescope at 1540 MHz. At that frequency, the change of relative intensity between the leading and trailing components is the predominant feature of mode switching. The intensity ratios between the leading and trailing components are measured for the individual profiles averaged over a few minutes. It is found that the ratios follow normal distributions, where the abnormal mode has a greater typical width than the normal mode, indicating that the abnormal mode is less stable than the normal mode. Our data show that 84.9% of the time for PSR B0329+54 was in the normal mode and 15.1% was in the abnormal mode. From the two passages of eight-day quasi-continuous observations in 2004, supplemented by the daily data observed with the 15 m telescope at 610 MHz at Jodrell Bank Observatory, the intrinsic distributions of mode timescales are constrained with the Bayesian inference method. It is found that the gamma distribution with the shape parameter slightly smaller than 1 is favored over the normal, log-normal, and Pareto distributions. The optimal scale parameters of the gamma distribution are 31.5 minutes for the abnormal mode and 154 minutes for the normal mode. The shape parameters have very similar values, i.e., 0.75 +0.22 – 0 .17 for the normal mode and 0.84 +0.28 – 0 .22 for the abnormal mode, indicating that the physical mechanisms in both modes may be the same. No long-term modulation of the relative intensity ratios was found for either mode, suggesting that the mode switching was stable. The intrinsic timescale distributions, constrained for this pulsar for the first time, provide valuable information to understand the physics of mode switching.

The NuSTAR view of the non-thermal emission from PSR J0437-4715

DEFF Research Database (Denmark)

Guillot, S.; Kaspi, V M; Archibald, Robert F.

2016-01-01

We present a hard X-ray Nuclear Spectroscopic Telescope Array (NuSTAR) observation of PSR J0437-4715, the nearest millisecond pulsar. The known pulsations at the apparent pulse period similar to 5.76 ms are observed with a significance of 3.7 sigma, at energies up to 20 keV above which the Nu...... by combining model fits to the pulsar's phase-folded light curve with the pulsar's well-defined mass and distance from radio timing observations....

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.

Pulsar-irradiated stars in dense globular clusters

Science.gov (United States)

Tavani, Marco

1992-01-01

We discuss the properties of stars irradiated by millisecond pulsars in 'hard' binaries of dense globular clusters. Irradiation by a relativistic pulsar wind as in the case of the eclipsing millisecond pulsar PSR 1957+20 alter both the magnitude and color of the companion star. Some of the blue stragglers (BSs) recently discovered in dense globular clusters can be irradiated stars in binaries containing powerful millisecond pulsars. The discovery of pulsar-driven orbital modulations of BS brightness and color with periods of a few hours together with evidence for radio and/or gamma-ray emission from BS binaries would valuably contribute to the understanding of the evolution of collapsed stars in globular clusters. Pulsar-driven optical modulation of cluster stars might be the only observable effect of a new class of binary pulsars, i.e., hidden millisecond pulsars enshrouded in the evaporated material lifted off from the irradiated companion star.

Some Arguments in Support of the Association of PSR B1706-44 with the Supernova Remnant G343.1-2.3

Science.gov (United States)

Bock, D. C.-J.; Gvaramadze, V. V.

We present some arguments in support of the association of the pulsar PSR B1706-44 with the supernova remnant G343.1-2.3, based on the idea that these objects could be the result of a supernova explosion within a mushroom-like cavity (created by the supernova progenitor wind breaking out of the parent molecular cloud). We suggest that in addition to the known bright "half" of G343.1-2.3 there should exist a more extended and weaker component, such that the actual shape of G343.1 2.3 is similar to that of the well-known SNR VRO 42.05.01. We have found such a component in archival radio data.

Binary millisecond pulsar discovery via gamma-ray pulsations.

Science.gov (United States)

Pletsch, H J; Guillemot, L; 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; Çelik, 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; den Hartog, P R; Hayashida, M; Hays, E; Hill, A B; Hou, X; Hughes, R E; Jóhannesson, 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; Rainò, S; Rando, R; Ray, P S; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Romani, R W; Romoli, C; Sanchez, D A; Saz Parkinson, P M; Schulz, A; Sgrò, C; do Couto e Silva, 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

2012-12-07

Millisecond pulsars, 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.

Discovery of a 105-ms X-ray Pulsar in Kesteven-79: On the Nature of Compact Central Objects in Supernova Remnants

Science.gov (United States)

Gotthelf, E. V.; Halpern, J. P.; Seward, F. D.

2005-01-01

We report the discovery of 105-ms X-ray pulsations from the compact central object (CCO) in the supernova remnant \\snr\\ using data acquired with the {\\it Newton X-Ray Multi-Mirror Mission). Using two observations of the pulsar taken 6-days apart we derive an upper limit on its spin-down rate of $\\dot P 18.5$-kyr. The latter exceeds the remnant's estimated age, suggesting that the pulsar was born spinning near its current period. The X-ray spectrum of \\psr\\ is best characterized as a blackbody of temperature $kT {BB) =, 0.43\\pm0.02$ keV, radius $R-{BB) \\approx 1.3$-km, and $I{\\rm bol) = 5.2 \\times 10A{33)$ ergs-sSA{-1)$ at $d = 7.1$-kpc. The sinusoidal light curve is modulated with a pulsed fraction of $>45\\%$, suggestive of a small hot spot on the surface of the rotating neutron star. The lack of a discernible pulsar wind nebula is consistent with an interpretation of \\psr\\ as a rotation-powered pulsar whose spin-down luminosity falls below the empirical threshold for generating bright wind nebulae, $\\dot E-{\\rm c) = 4 \\times 10A{36)$-ergs-sSA{-I)$. The age discrepancy suggests that its $\\dot E$ has always been below $\\dot E c$, perhaps a distinguishing property of the CCOs. Alternatively, the X-ray spectrum of \\psr\\ suggests a low-luminosity AXP, but the weak inferred $B-{\\rm p)$ field is incompatible with a magnetar theory of its X-ray luminosity. The ordinary spin parameters discovered from \\psr\\ highlight the inability of existing theories to explain the high luminosities and temperatures of CCO thermal X-ray spectra.

γ rays of 0.3-30 MeV from PSR0833 - 45

International Nuclear Information System (INIS)

Tuemer, O.T.; Long, J.; O'Neill, T.; Zych, A.; White, R.S.

1984-01-01

Pulsed γ rays from the Vela pulsar PSR0833-45 are reported for the first time at the medium energies, E, of 0.3-30 MeV. They were observed with the double scatter γ-ray telescope 31 days after a large glitch in the pulsar period. The first and second pulses were detected from single scatters in the top scintillators, S1, at energies > 0.3 MeV, and by double scatters from all detector cell pairs at energies of 1-30 MeV. The phase separation of the two pulses is 0.43 +- 0.02 at the same absolute phases previously found by SAS 2 and COS B for E > 35 MeV. The energy distribution with six points from 0.3 to 30 MeV appears to bend away from the COS B power law at the lower energies and is well below the HEAO 1 upper limits. (author)

PSR J0538+2817 As The Remnant Of The First Supernova Explosion in a Massive Binary

Science.gov (United States)

Gvaramadze, V. V.

2006-08-01

It is generally accepted that the radio pulsar PSR J0538+2817 is associated with the supernova remnant (SNR) S147. The only problem for the association is the obvious discrepancy (Kramer et al. 2003) between the kinematic age of the system of ~30 kyr (estimated from the angular offset of the pulsar from the geometric center of the SNR and pulsar's proper motion) and the characteristic age of the pulsar of ~600 kyr. To reconcile these ages one can assume that the pulsar was born with a spin period close to the present one (Kramer et al. 2003; Romani & Ng 2003). We propose an alternative explanation of the age discrepancy based on the fact that PSR J0538+2817 could be the stellar remnant of the first supernova explosion in a massive binary system and therefore could be as old as indicated by its characteristic age. Our proposal implies that S147 is the diffuse remnant of the second supernova explosion (that disrupted the binary system) and that a much younger second neutron star (not necessarily manifesting itself as a radio pulsar) should be associated with S147. We use the existing observational data on the system PSR J0538+2817/SNR S147 to suggest that the progenitor of the supernova that formed S147 was a Wolf-Rayet star (so that the supernova explosion occurred within a wind bubble surrounded by a massive shell) and to constrain the parameters of the binary system. We also restrict the magnitude and direction of the kick velocity received by the young neutron star at birth and find that the kick vector should not strongly deviate from the orbital plane of the binary system.

Synchronous x-ray and radio mode switches: a rapid global transformation of the pulsar magnetosphere.

Science.gov (United States)

Hermsen, W; Hessels, J W T; Kuiper, L; van Leeuwen, J; Mitra, D; de Plaa, J; Rankin, J M; Stappers, B W; Wright, G A E; Basu, R; Alexov, A; Coenen, T; Grießmeier, J-M; Hassall, T E; Karastergiou, A; Keane, E; Kondratiev, V I; Kramer, M; Kuniyoshi, M; Noutsos, A; Serylak, M; Pilia, M; Sobey, C; Weltevrede, P; Zagkouris, K; Asgekar, A; Avruch, I M; Batejat, F; Bell, M E; Bell, M R; Bentum, M J; Bernardi, G; Best, P; Bîrzan, L; Bonafede, A; Breitling, F; Broderick, J; Brüggen, M; Butcher, H R; Ciardi, B; Duscha, S; Eislöffel, J; Falcke, H; Fender, R; Ferrari, C; Frieswijk, W; Garrett, M A; de Gasperin, F; de Geus, E; Gunst, A W; Heald, G; Hoeft, M; Horneffer, A; Iacobelli, M; Kuper, G; Maat, P; Macario, G; Markoff, S; McKean, J P; Mevius, M; Miller-Jones, J C A; Morganti, R; Munk, H; Orrú, E; Paas, H; Pandey-Pommier, M; Pandey, V N; Pizzo, R; Polatidis, A G; Rawlings, S; Reich, W; Röttgering, H; Scaife, A M M; Schoenmakers, A; Shulevski, A; Sluman, J; Steinmetz, M; Tagger, M; Tang, Y; Tasse, C; ter Veen, S; Vermeulen, R; van de Brink, R H; van Weeren, R J; Wijers, R A M J; Wise, M W; Wucknitz, O; Yatawatta, S; Zarka, P

2013-01-25

Pulsars emit from low-frequency radio waves up to high-energy gamma-rays, generated anywhere from the stellar surface out to the edge of the magnetosphere. Detecting correlated mode changes across the electromagnetic spectrum is therefore key to understanding the physical relationship among the emission sites. Through simultaneous observations, we detected synchronous switching in the radio and x-ray emission properties of PSR B0943+10. When the pulsar is in a sustained radio-"bright" mode, the x-rays show only an unpulsed, nonthermal component. Conversely, when the pulsar is in a radio-"quiet" mode, the x-ray luminosity more than doubles and a 100% pulsed thermal component is observed along with the nonthermal component. This indicates rapid, global changes to the conditions in the magnetosphere, which challenge all proposed pulsar emission theories.

HIGH-ENERGY OBSERVATIONS OF PSR B1259–63/LS 2883 THROUGH THE 2014 PERIASTRON PASSAGE: CONNECTING X-RAYS TO THE GeV FLARE

Energy Technology Data Exchange (ETDEWEB)

Tam, P. H. T.; Li, K. L.; Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Takata, J. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Okazaki, A. T. [Faculty of Engineering, Hokkai-Gakuen University, Toyohira-ku, Sapporo 062-8605 (Japan); Hui, C. Y., E-mail: phtam@phys.nthu.edu.tw [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

2015-01-01

The binary system PSR B1259–63/LS 2883 is well sampled in radio, X-rays, and TeV γ-rays, and shows orbital-phase-dependent variability in these frequencies. The first detection of GeV γ-rays from the system was made around the 2010 periastron passage. In this Letter, we present an analysis of X-ray and γ-ray data obtained by the Swift/XRT, NuSTAR/FPM, and Fermi/LAT, through the recent periastron passage which occurred on 2014 May 4. While PSR B1259–63/LS 2883 was not detected by the Large Area Telescope before and during this passage, we show that the GeV flares occurred at a similar orbital phase as in early 2011, thus establishing the repetitive nature of the post-periastron GeV flares. Multiple flares each lasting for a few days have been observed and short-term variability is seen as well. We also found X-ray flux variation contemporaneous with the GeV flare for the first time. Strong evidence of the keV-to-GeV connection came from the broadband high-energy spectra, which we interpret as synchrotron radiation from the shocked pulsar wind.

Pulsed Gamma Rays from the Original Millisecond and Black Widow Pulsars: A Case for Caustic Radio Emission?

Science.gov (United States)

Guillemot, L.; Johnson, T. J.; Venter, C.; Kerr, M.; Pancrazi, B.; Livingstone, M.; Janssen, G. H.; Jaroenjittichai, P.; Kramer, M.; Cognard, I.;

Simultaneous Chandra and VLA Observations of the Transitional Millisecond Pulsar PSR J1023+0038: Anti-correlated X-Ray and Radio Variability

Science.gov (United States)

Bogdanov, Slavko; Deller, Adam T.; Miller-Jones, James C. A.; Archibald, Anne M.; Hessels, Jason W. T.; Jaodand, Amruta; Patruno, Alessandro; Bassa, Cees; D’Angelo, Caroline

2018-03-01

We present coordinated Chandra X-ray Observatory and Karl G. Jansky Very Large Array observations of the transitional millisecond pulsar PSR J1023+0038 in its low-luminosity accreting state. The unprecedented five hours of strictly simultaneous X-ray and radio continuum coverage for the first time unambiguously show a highly reproducible, anti-correlated variability pattern. The characteristic switches from the X-ray high mode into a low mode are always accompanied by a radio brightening with a duration that closely matches the X-ray low mode interval. This behavior cannot be explained by a canonical inflow/outflow accretion model where the radiated emission and the jet luminosity are powered by, and positively correlated with, the available accretion energy. We interpret this phenomenology as alternating episodes of low-level accretion onto the neutron star during the X-ray high mode that are interrupted by rapid ejections of plasma by the active rotation-powered pulsar, possibly initiated by a reconfiguration of the pulsar magnetosphere, that cause a transition to a less X-ray luminous mode. The observed anti-correlation between radio and X-ray luminosity has an additional consequence: transitional MSPs can make excursions into a region of the radio/X-ray luminosity plane previously thought to be occupied solely by black hole X-ray binary sources. This complicates the use of this luminosity relation for identifying candidate black holes, suggesting the need for additional discriminants when attempting to establish the true nature of the accretor.

THE GREEN BANK TELESCOPE 350 MHz DRIFT-SCAN SURVEY II: DATA ANALYSIS AND THE TIMING OF 10 NEW PULSARS, INCLUDING A RELATIVISTIC BINARY

Energy Technology Data Exchange (ETDEWEB)

Lynch, Ryan S.; Kaspi, Victoria M.; Archibald, Anne M.; Karako-Argaman, Chen [Department of Physics, McGill University, 3600 University Street, Montreal, QC H3A 2T8 (Canada); Boyles, Jason; Lorimer, Duncan R.; McLaughlin, Maura A.; Cardoso, Rogerio F. [Department of Physics, West Virginia University, 111 White Hall, Morgantown, WV 26506 (United States); Ransom, Scott M. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Stairs, Ingrid H.; Berndsen, Aaron; Cherry, Angus; McPhee, Christie A. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Hessels, Jason W. T.; Kondratiev, Vladislav I.; Van Leeuwen, Joeri [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990-AA Dwingeloo (Netherlands); Epstein, Courtney R. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Pennucci, Tim [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Roberts, Mallory S. E. [Eureka Scientific Inc., 2452 Delmer Street, Suite 100, Oakland, CA 94602 (United States); Stovall, Kevin, E-mail: rlynch@physics.mcgill.ca [Center for Advanced Radio Astronomy and Department of Physics and Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States)

2013-02-15

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 {approx}10,300 deg{sup 2} and all of the data have now been fully processed. We have discovered a total of 31 new pulsars, 7 of which are recycled pulsars. A companion paper by Boyles et al. describes the survey strategy, sky coverage, and instrumental setup, 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.

DISCOVERY OF HIGH-ENERGY GAMMA-RAY EMISSION FROM THE BINARY SYSTEM PSR B1259-63/LS 2883 AROUND PERIASTRON WITH FERMI

International Nuclear Information System (INIS)

Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Borgland, A. W.; Buehler, R.; Cameron, R. A.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Buson, S.; Bellazzini, R.; Bregeon, J.; Bonamente, E.; Brigida, M.; Bruel, P.; Caliandro, G. A.

2011-01-01

We report on the discovery of ≥100 MeV γ-rays from the binary system PSR B1259-63/LS 2883 using the Large Area Telescope (LAT) on board Fermi. The system comprises a radio pulsar in orbit around a Be star. We report on LAT observations from near apastron to ∼128 days after the time of periastron, t p , on 2010 December 15. No γ-ray emission was detected from this source when it was far from periastron. Faint γ-ray emission appeared as the pulsar approached periastron. At ∼t p + 30 days, the ≥100 MeV γ-ray flux increased over a period of a few days to a peak flux 20-30 times that seen during the pre-periastron period, but with a softer spectrum. For the following month, it was seen to be variable on daily timescales, but remained at ∼(1-4) x 10 -6 cm -2 s -1 before starting to fade at ∼t p + 57 days. The total γ-ray luminosity observed during this period is comparable to the spin-down power of the pulsar. Simultaneous radio and X-ray observations of the source showed no corresponding dramatic changes in radio and X-ray flux between the pre-periastron and post-periastron flares. We discuss possible explanations for the observed γ-ray-only flaring of the source.

PSR J0751+1807: un ajuste a los parámetros característicos del sistema binario

Science.gov (United States)

De Vito, M. A.; Benvenuto, O. G.

PSR J0751+1807 is a millisecond pulsar belonging to a binary system with a low mass white dwarf companion. This system belongs to the group of recycled pulsars by mass transfer from a close companion, accelerating the pulsar rotation in this process. The orbital period for the system is of 6 hours. In this work we show our fit to the characteristic parameters of the system presented by Nice et al. (2005) FULL TEXT IN SPANISH

The binary nature of PSR J2032+4127

International Nuclear Information System (INIS)

Lyne, A. G.; Stappers, B. W.; Keith, M. J.; Ray, P. S.; Kerr, M.

2015-01-01

PSR J2032+4127 is a γ-ray and radio-emitting pulsar which has been regarded as a young luminous isolated neutron star. However, its recent spin-down rate has extraordinarily increased by a factor of 2. Here we present evidence that this is due to its motion as a member of a highly-eccentric binary system with an ~15–M⊙ Be star, MT91 213. Timing observations show that, not only are the positions of the two stars coincident within 0.4 arcsec, but timing models of binary motion of the pulsar fit the data much better than a model of a young isolated pulsar. MT91 213, and hence the pulsar, lie in the Cyg OB2 stellar association, which is at a distance of only 1.4–1.7 kpc. The pulsar is currently on the near side of, and accelerating towards, the Be star, with an orbital period of 20–30 yr. Finally, the next periastron is well constrained to occur in early 2018, providing an opportunity to observe enhanced high-energy emission as seen in other Be-star binary systems.

X-Ray Study of Variable Gamma-Ray Pulsar PSR J2021+4026

Science.gov (United States)

Wang, H. H.; Takata, J.; Hu, C.-P.; Lin, L. C. C.; Zhao, J.

2018-04-01

PSR J2021+4026 showed a sudden decrease in the gamma-ray emission at the glitch that occurred around 2011 October 16, and a relaxation of the flux to the pre-glitch state at around 2014 December. We report X-ray analysis results of the data observed by XMM-Newton on 2015 December 20 in the post-relaxation state. To examine any change in the X-ray emission, we compare the properties of the pulse profiles and spectra at the low gamma-ray flux state and at the post-relaxation state. The phase-averaged spectra for both states can be well described by a power-law component plus a blackbody component. The former is dominated by unpulsed emission and probably originated from the pulsar wind nebula as reported by Hui et al. The emission property of the blackbody component is consistent with the emission from the polar cap heated by the back-flow bombardment of the high-energy electrons or positrons that were accelerated in the magnetosphere. We found no significant change in the X-ray emission properties between two states. We suggest that the change of the X-ray luminosity is at an order of ∼4%, which is difficult to measure with the current observations. We model the observed X-ray light curve with the heated polar cap emission, and we speculate that the observed large pulsed fraction is owing to asymmetric magnetospheric structure.

An algorithm for determining the rotation count of pulsars

Science.gov (United States)

Freire, Paulo C. C.; Ridolfi, Alessandro

2018-06-01

We present here a simple, systematic method for determining the correct global rotation count of a radio pulsar; an essential step for the derivation of an accurate phase-coherent ephemeris. We then build on this method by developing a new algorithm for determining the global rotational count for pulsars with sparse timing data sets. This makes it possible to obtain phase-coherent ephemerides for pulsars for which this has been impossible until now. As an example, we do this for PSR J0024-7205aa, an extremely faint Millisecond pulsar (MSP) recently discovered in the globular cluster 47 Tucanae. This algorithm has the potential to significantly reduce the number of observations and the amount of telescope time needed to follow up on new pulsar discoveries.

LOFAR Discovery of the Fastest-spinning Millisecond Pulsar in the Galactic Field

NARCIS (Netherlands)

Bassa, C.G.; Pleunis, Z.; Hessels, J.W.T.; Ferrara, E.C.; Breton, R.P.; Gusinskaia, N.V.; Kondratiev, V.I.; Sanidas, S.; Nieder, L.; Clark, C.J.; Li, T.; van Amesfoort, A.S.; Burnett, T.H.; Camilo, F.; Michelson, P.F.; Ransom, S.M.; Ray, P.S.; Wood, K.

2017-01-01

We report the discovery of PSR J0952−0607, a 707 Hz binary millisecond pulsar that is now the fastest-spinning neutron star known in the Galactic field (i.e., outside of a globular cluster). PSR J0952−0607 was found using LOFAR at a central observing frequency of 135 MHz, well below the 300 MHz to 3

Tests of general relativity from timing the double pulsar.

Science.gov (United States)

Kramer, M; Stairs, I H; Manchester, R N; McLaughlin, M A; Lyne, A G; Ferdman, R D; Burgay, M; Lorimer, D R; Possenti, A; D'Amico, N; Sarkissian, J M; Hobbs, G B; Reynolds, J E; Freire, P C C; Camilo, F

2006-10-06

The double pulsar system PSR J0737-3039A/B is unique in that both neutron stars are detectable as radio pulsars. They are also known to have much higher mean orbital velocities and accelerations than those of other binary pulsars. The system is therefore a good candidate for testing Einstein's theory of general relativity and alternative theories of gravity in the strong-field regime. We report on precision timing observations taken over the 2.5 years since its discovery and present four independent strong-field tests of general relativity. These tests use the theory-independent mass ratio of the two stars. By measuring relativistic corrections to the Keplerian description of the orbital motion, we find that the "post-Keplerian" parameter s agrees with the value predicted by general relativity within an uncertainty of 0.05%, the most precise test yet obtained. We also show that the transverse velocity of the system's center of mass is extremely small. Combined with the system's location near the Sun, this result suggests that future tests of gravitational theories with the double pulsar will supersede the best current solar system tests. It also implies that the second-born pulsar may not have formed through the core collapse of a helium star, as is usually assumed.

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.

A DETAILED X-RAY INVESTIGATION OF PSR J2021+4026 AND THE γ-CYGNI SUPERNOVA REMNANT

Energy Technology Data Exchange (ETDEWEB)

Hui, C. Y.; Seo, K. A. [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Lin, L. C. C.; Huang, R. H. H.; Wu, J. H. K.; Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Hu, C. P.; Chou, Y. [Graduate Institute of Astronomy, National Central University, Jhongli 32001, Taiwan (China); Trepl, L. [Astrophysikalisches Institut und Universitäts-Sternwarte, Universität Jena, Schillergäßchen 2-3, D-07745 Jena (Germany); Takata, J.; Wang, Y.; Cheng, K. S., E-mail: cyhui@cnu.ac.kr [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong)

2015-01-20

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 × 10{sup 6} 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.

A SEARCH FOR VERY HIGH ENERGY GAMMA RAYS FROM THE MISSING LINK BINARY PULSAR J1023+0038 WITH VERITAS

Energy Technology Data Exchange (ETDEWEB)

Aliu, E. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Archambault, S. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Archer, A.; Buckley, J. H.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W.; Cerruti, M. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Bird, R. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Biteau, J. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Buchovecky, M. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cardenzana, J. V; Dickinson, H. J.; Eisch, J. D. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Chen, X. [Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam-Golm (Germany); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Cui, W.; Feng, Q. [Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907 (United States); Falcone, A., E-mail: ester.aliu.fuste@gmail.com, E-mail: gtrichards@gatech.edu, E-mail: masha.chernyakova@dcu.ie, E-mail: malloryr@gmail.com [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); and others

2016-11-10

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.

Test of post-newtonian conservation laws in the binary system PSR 1913+16

International Nuclear Information System (INIS)

Will, C.M.

1976-01-01

Observations that set upper limits on secular changes in the pulsar period and orbital period in the binary system PSR 1913+16 may provide a test of post-Newtonian conservation laws. According to some metric theories of gravitation, the center of mass of a binary system may be accelerated in the direction of the periastron of the orbit because of a violation of post-Newtonian momentum conservation. In the binary system PSR 1913+16, this effect could produce secular changes in both pulsar and orbital periods (changing overall Doppler shift) as large as two parts in 10 6 per year. The size of the effect is proportional to the sine of the angle of periastron, to the difference in the masses of the components of the binary system, and to the combination of parametrized post-Newtonian parameters α 3 +zeta 2 -zeta/subw/. This combination is zero in any theory that predicts conserved total momentum for isolated systems (including general relativity and Brans-Dicke theory). Although solar-system experiments constrain α 3 and zeta/subw/ to be small, no decent direct limit has been placed on zeta 2 . Other possible sources of secular period changes in PSR 1913+16 are discussed and compared with this effect. It is also shown that a breakdown in the equality of active and passive gravitational masses (violation of ''Newton's third law'') leads only to periodic, unobservable orbital effects in a system like PSR 1913+16

A search for thermal extreme ultraviolet radiation from nearby pulsars

International Nuclear Information System (INIS)

Greenstein, G.; Margon, B.

1977-01-01

We present the first extreme ultraviolet (100-1000 A) observations of radio pulsars. Using an EUV telescope carried aboard the Apollo-Soyuz mission, data were acquired on the nearby pulsars PSR 1133 + 16, 1451 - 68 and 1929 + 10. The data are interpreted to set limits on the effective temperatures of the neutron stars, yielding T 5 K in the best cases, and the limits compared with theoretical predictions. (orig./BJ) [de

Planets around pulsars - Implications for planetary formation

Science.gov (United States)

Bodenheimer, Peter

1993-01-01

Data on planets around pulsars are summarized, and different models intended to explain the formation mechanism are described. Both theoretical and observational evidence suggest that very special circumstances are required for the formation of planetary systems around pulsars, namely, the prior presence of a millisecond pulsar with a close binary companion, probably a low mass main-sequence star. It is concluded that the discovery of two planets around PSR 1257+12 is important for better understanding the problems of dynamics and stellar evolution. The process of planetary formation should be learned through intensive studies of the properties of disks near young objects and application of techniques for detection of planets around main-sequence solar-type stars.

Planetesimals around nearby millisecond pulsars

International Nuclear Information System (INIS)

Chakrabarti, S.K.

1992-05-01

We predict that it is possible to observe line emissions of OH, CN and C 2 from the planetesimals around some of the nearby millisecond pulsars, such as PSR1257+12. Observation of these lines will provide an independent test of either an existing planetary system or one which is in the process of formation. (author). 11 refs, 1 tab

NuSTAR Discovery Of A Young, Energetic Pulsar Associated with the Luminous Gamma-Ray Source HESS J1640-465

Science.gov (United States)

Gotthelf, E. V.; Tomsick, J. A.; Halpern, J. P.; Gelfand, J. D.; Harrison, F. A.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Hailey, J. C.; Kaspi, V. M.;

The VELA-X-Pulsar Wind Nebula Revisited with Four Years of Fermi Large Area Telescope Observations

Science.gov (United States)

Grondin, M. -H.; Romani, R. W.; Lemoine-Goumard, M.; Guillemot, L.; Harding, Alice K.; Reposeur, T.

2013-01-01

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 2deg × 3deg south of the pulsar and observed in the radio, X-ray, and very high energy ?-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.

PSR 1913 + 16: endpoints of speculation. A critical discussion of possible companions and progenitors

Energy Technology Data Exchange (ETDEWEB)

Webbink, R F [Cambridge Univ. (UK). Inst. of Astronomy

1975-01-01

We attempt a comprehensive discussion of the nature and origin of the binary pulsar PSR 1913 + 16. It is shown that the system must have been binary before the creation of the pulsar. Main-sequence stars, white dwarfs, helium stars, neutron stars and black holes are considered as possible secondaries. It is shown that the pulsar component must have been a helium star before collapse. The companion is probably a neutron star, although a helium star or black hole cannot be excluded. We suggest that the pulsar was formed when a moderately massive (2 to 8 M(S)) helium star overfilled its Roche lobe and was stripped of its helium-rich envelope. Core collapse and carbon ignition followed rapidly, creating the neutron star we observe.

Radio observations of a galactic high energy gamma-ray source

Energy Technology Data Exchange (ETDEWEB)

Giacani, E.; Rovero, A.C. [Instituto de Astronomia y Fisica del Espacio, Buenos Aires (Argentina)

2001-10-01

PSR B1706-44 is one of the very few galactic pulsars that has been discovered at TeV energies. PSR B1706-44 has been also detected in the X-ray domain. It has been suggested that the high energy radiation could be due to inverse Compton radiation from a pulsar wind nebula (PWN). It was reported on VLA high-resolution observations of a region around the pulsar PSR B1706-44 at 1.4, 4.8 and 8.4 GHz. The pulsar appears embedded in a synchrotron nebula. It was proposed that this synchrotron nebula is the radio counterpart of the high energy emission powered by the spin-down energy of the pulsar.

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.;

New binary pulsar in a highy eccentric orbit

International Nuclear Information System (INIS)

Stokes, G.H.; Taylor, J.H.; Dewey, R.J.

1985-01-01

We report the discovery of PSR 2303+46, the fifth radio pulsar known to be in a gravitationally bound orbit around another star. The pulsar period (1.066 s) and the orbital eccentricity (0.658) are the largest amount the five binary systems, while the orbital period (12./sup d/34) lies near the middle of the range. Evolutionary considerations suggest strongly that the companion is another neutron star. The general relativistic precession of periastron should be observable within 1 or 2 yr and, when measured, will specify the total mass of the two stars

Polarimetry of the millisecond pulsar

Energy Technology Data Exchange (ETDEWEB)

Stinebring, D R

1983-04-21

Polarization observations of the millisecond pulsar PSR1937+21 at 1415 and 2380 MHz were made with the 305-m telescope at the Arecibo Observatory in January 1983. The main pulse is found to depolarize substantially, while the interpulse polarization almost doubles. Evidence for orthogonally polarized radiation was detected on the edges facing across the 173 deg of longitude separating the main pulse from the interpulse, accounting for the approximately 90-deg difference in position angle. From the spectral-index difference (close to 1.0 over the frequency range observed) it is inferred that the interpulse may dominate the main pulse below 700 MHz; such behavior is noted to be similar to that of the physically different Crab pulsar.

Multifrequency behaviour of the anomalous events of PSR J0922+0638

Science.gov (United States)

Shaifullah, G.; Tiburzi, C.; Osłowski, S.; Verbiest, J. P. W.; Szary, A.; Künsemöller, J.; Horneffer, A.; Anderson, J.; Kramer, M.; Schwarz, D. J.; Mann, G.; Steinmetz, M.; Vocks, C.

2018-06-01

PSR J0922+0638 (B0919+06) shows unexplained anomalous variations in the on-pulse phase, where the pulse appears to episodically move to an earlier longitude for a few tens of rotations before reverting to the usual phase for approximately several hundred to more than a thousand rotations. These events, where the pulse moves in phase by up to 5°, have been previously detected in observations from ˜300 to 2000 MHz. We present simultaneous observations from the Effelsberg 100-m radio telescope at 1350 MHz and the Bornim (Potsdam) station of the LOw Frequency ARray at 150 MHz. Our observations present the first evidence for an absence of the anomalous phase-shifting behaviour at 150 MHz. Instead, the observed intensity at the usual pulse-phase typically decreases, often showing a pseudo-nulling feature corresponding to the times when phase shifts are observed at 1350 MHz. The presence of weak emission at the usual pulse-phase supports the theory that these shifts may result from processes similar to the `profile-absorption' expected to operate for PSR J0814+7429 (B0809+74). A possible mechanism for this could be intrinsic variations of the emission within the pulsar's beam combined with absorption by expanding shells of electrons in the line of sight.

Discovery of a radio nebula around PSR J0855-4644

Science.gov (United States)

Maitra, C.; Roy, S.; Acero, F.; Gupta, Y.

2018-03-01

We report the discovery of a diffuse radio emission around PSR J0855-4644 using an upgraded GMRT (uGMRT) observation at 1.35 GHz. The radio emission is spatially coincident with the diffuse X-ray pulsar wind nebula (PWN) seen with XMM-Newton but is much larger in extent compared to the compact axisymmetric PWN seen with Chandra. The morphology of the emission, with a bright partial ring-like structure and two faint tail-like features strongly resembles a bow shock nebula, and indicates a velocity of 100 km/s through the ambient medium. We conclude that the emission is most likely to be associated with the radio PWN of PSR J0855-4644. From the integrated flux density, we estimate the energetics of the PWN.

Separated before birth: pulsars B2020+28 and B2021+51 as the remnants of runaway stars

OpenAIRE

Gvaramadze, V. V.

2007-01-01

Astrometric data on the pulsars B2020+28 and B2021+51 suggest that they originated within several parsecs of each other in the direction of the Cyg OB2 association. It was proposed that the pulsars share their origin in a common massive binary and were separated at the birth of the second pulsar following the asymmetric supernova explosion. We consider a different scenario for the origin of the pulsar pair based on a possibility that the pulsars were separated before their birth and that they...

Geriatric Pulsar Still Kicking

Science.gov (United States)

2009-02-01

The oldest isolated pulsar ever detected in X-rays has been found with NASA's Chandra X-ray Observatory. This very old and exotic object turns out to be surprisingly active. The pulsar, PSR J0108-1431 (J0108 for short) is about 200 million years old. Among isolated pulsars -- ones that have not been spun-up in a binary system -- it is over 10 times older than the previous record holder with an X-ray detection. At a distance of 770 light years, it is one of the nearest pulsars known. Pulsars are born when stars that are much more massive than the Sun collapse in supernova explosions, leaving behind a small, incredibly weighty core, known as a neutron star. At birth, these neutron stars, which contain the densest material known in the Universe, are spinning rapidly, up to a hundred revolutions per second. As the rotating beams of their radiation are seen as pulses by distant observers, similar to a lighthouse beam, astronomers call them "pulsars". Astronomers observe a gradual slowing of the rotation of the pulsars as they radiate energy away. Radio observations of J0108 show it to be one of the oldest and faintest pulsars known, spinning only slightly faster than one revolution per second. The surprise came when a team of astronomers led by George Pavlov of Penn State University observed J0108 in X-rays with Chandra. They found that it glows much brighter in X-rays than was expected for a pulsar of such advanced years. People Who Read This Also Read... Chandra Data Reveal Rapidly Whirling Black Holes Milky Way’s Giant Black Hole Awoke from Slumber 300 Years Ago Erratic Black Hole Regulates Itself Celebrate the International Year of Astronomy Some of the energy that J0108 is losing as it spins more slowly is converted into X-ray radiation. The efficiency of this process for J0108 is found to be higher than for any other known pulsar. "This pulsar is pumping out high-energy radiation much more efficiently than its younger cousins," said Pavlov. "So, although it

DISCOVERY OF GAMMA-RAY ORBITAL MODULATION IN THE BLACK WIDOW PSR J1311–3430

Energy Technology Data Exchange (ETDEWEB)

Xing, Yi; Wang, Zhongxiang [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

2015-05-10

We report our discovery of orbitally modulated γ-ray emission from the black widow system PSR J1311−3430. We analyze the Fermi Large Area Telescope data during the off-pulse phase interval of the pulsar and find the orbital modulation signal at a ∼3σ confidence level. Further spectral analysis shows no significant differences for the spectra obtained during the bright and faint orbital phase ranges. A simple sinusoid-like function can describe the modulation. Given these properties, we suggest that the intrabinary γ-ray emission arises from the region close to the companion and the modulation is caused by the occultation of the emitting region by the companion, similar to that is seen in the transitional millisecond pulsar binary (MSP) PSR J1023+0038. Considering the X-ray detection of intrabinary shock emission from eclipsing MSP binaries recently reported, this discovery further suggests the general existence of intrabinary γ-ray emission from them.

NuSTAR discovery of a young, energetic pulsar associated with the luminous gamma-ray source HESS J1640–465

Energy Technology Data Exchange (ETDEWEB)

Gotthelf, E. V.; Halpern, J. P.; Hailey, J. C. [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027-6601 (United States); Tomsick, J. A.; Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Gelfand, J. D. [NYU Abu Dhabi, PO Box 129188, Abu Dhabi (United Arab Emirates); Harrison, F. A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Christensen, F. E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, 2800 Lyngby (Denmark); Kaspi, V. M. [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Stern, D. K. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Zhang, W. W., E-mail: eric@astro.columbia.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2014-06-20

We report the discovery of a 206 ms pulsar associated with the TeV γ-ray source HESS J1640–465 using the Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray observatory. PSR J1640–4631 lies within the shell-type supernova remnant (SNR) G338.3–0.0, and coincides with an X-ray point source and putative pulsar wind nebula (PWN) previously identified in XMM-Newton and Chandra images. It is spinning down rapidly with period derivative P-dot = 9.758(44) × 10{sup –13}, yielding a spin-down luminosity E-dot = 4.4 × 10{sup 36} erg s{sup –1}, characteristic age τ{sub c}≡P/2 P-dot = 3350 yr, and surface dipole magnetic field strength B{sub s} = 1.4 × 10{sup 13} G. For the measured distance of 12 kpc to G338.3–0.0, the 0.2-10 TeV luminosity of HESS J1640–465 is 6% of the pulsar's present E-dot . The Fermi source 1FHL J1640.5–4634 is marginally coincident with PSR J1640–4631, but we find no γ-ray pulsations in a search using five years of Fermi Large Area Telescope (LAT) data. The pulsar energetics support an evolutionary PWN model for the broadband spectrum of HESS J1640–465, provided that the pulsar's braking index is n ≈ 2, and that its initial spin period was P {sub 0} ∼ 15 ms.

Pulsed Gamma-Rays From the Millisecond Pulsar J0030+0451 with the Fermi Large Area Telescope

International Nuclear Information System (INIS)

Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Bastieri, Denis; Battelino, M.; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, Elliott D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, Thompson H.

2009-01-01

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 33 ergs s -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 -8 cm -2 s -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 γ /(dot E) ≅ 15% for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.

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.

Timing irregularities of PSR J1705-1906

Science.gov (United States)

Liu, Y. L.; Yuan, J. P.; Wang, J. B.; Liu, X. W.; Wang, N.; Yuen, R.

2018-05-01

Timing analysis of PSR J1705-1906 using data from Nanshan 25-m and Parkes 64-m radio telescopes, which span over fourteen years, shows that the pulsar exhibits significant proper motion, and rotation instability. We updated the astrometry parameters and the spin parameters of the pulsar. In order to minimize the effect of timing irregularities on measuring its position, we employ the Cholesky method to analyse the timing noise. We obtain the proper motion of -77(3) mas yr-1 in right ascension and -38(29) mas yr-1 in declination. The power spectrum of timing noise is analyzed for the first time, which gives the spectral exponent α =-5.2 for the power-law model indicating that the fluctuations in spin frequency and spin-down rate dominate the red noise. We detect two small glitches from this pulsar with fractional jump in spin frequency of Δ ν /ν ˜ 2.9 × 10^{-10} around MJD 55199 and Δ ν /ν ˜ 2.7× 10^{-10} around MJD 55953. Investigations of pulse profile at different time segments suggest no significant changes in the pulse profiles around the two glitches.

Radio Detection of the Fermi-LAT Blind Search Millisecond Pulsar J1311-3430

Science.gov (United States)

Ray, P. S.; Ransom, S. M.; Cheung, C. C.; Giroletti, M.; Cognard, I.; Camilo, F.; Bhattacharyya, B.; Roy, J.; Romani, R. W.; Ferrara, E. C.; Guillemot, L.; Johnston, S.; Keith, M.; Kerr, M.; Kramer, M.; Pletsch, H. J.; Saz Parkinson, P. M.; Wood, K. S.

2013-01-01

We report the detection of radio emission from PSR J1311-3430, the first millisecond pulsar (MSP) discovered in a blind search of Fermi Large Area Telescope (LAT) gamma-ray data. We detected radio pulsations at 2 GHz, visible for delay in the radio pulses as the pulsar appears from eclipse and we speculate on possible mechanisms for the non-detections of the pulse at other orbital phases and observing frequencies.

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

International Nuclear Information System (INIS)

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

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, 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.

Verification of f(R-gravity in binary pulsars

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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.

Axion mass limits from pulsar x rays

International Nuclear Information System (INIS)

Morris, D.E.

1984-12-01

Axions thermally emitted by a neutron star would be converted into x rays in the strong magnetic field surrounding the star. An improvement in the observational upper limit of pulsed x rays from the Vela pulsar (PSR 0833-45) by a factor of 12 would constrain the axion mass M/sub a/ -3 eV if the core is non-superfluid and at temperature T/sub c/ greater than or equal to 2 x 10 8 K. If the core is superfluid throughout, an improvement factor of 240 would be needed to provide the same constraint on the axion mass, while in the absence of superfluidity, an improvement factor of 200 could constrain M/sub a/ -4 eV. A search for modulated hard x rays from PSR 1509-58 or other young pulsars at presently attainable sensitivities may enable the setting of an upper limit for the axion mass. Observation of hard x rays from a very young hot pulsar with T/sub c/ greater than or equal to 7 x 10 8 K could set a firm bound on the axion mass, since neutron superfluidity is not expected above this temperature. The remaining axion mass range 6 x 10 -4 eV > M/sub a/ > 10 -5 eV (the cosmological lower bound) can be covered by an improved Sikivie type laboratory cavity detector for relic axions constituting the galactic halo. 48 refs

PROBING RELATIVISTIC WINDS: THE CASE OF PSR J07370-3039 A and B

International Nuclear Information System (INIS)

Arons, J

2004-01-01

We propose synchrotron absorption in a magnetosheath forming a cocoon around the magnetosphere of pulsar B to be the origin of the eclipse phenomena seen in the recently discovered double pulsar system PSRJ07370-3039 A and B. The magnetosheath enfolds the magnetosphere of pulsar B, where the relativistic wind from A collides with B's magnetic field. If this model is correct, it predicts the eclipses will clear at frequencies higher than those of the observations reported to date (nominally, above ν ∼ 5 GHz.) The model also predicts synchrotron emission at the level of a few to 10 (micro)Jy, peaking at ν ∼ 2.5 GHz with possible orbital modulation. We use simplified semi-analytic models to elucidate the structure of the B magnetosphere, showing that the A wind's dynamic pressure confines B's magnetic field to within a radius less than 50,000 km from B, smaller than B's light cylinder radius, on the ''daytime'' side (the side facing A). Downstream of B (''nightime''), B forms a magnetotail. We use particle-in-cell simulations to include the effects of magnetospheric rotation, showing that the magnetosheath has an asymmetric density distribution which may be responsible for the observed eclipse asymmetries. We use simple estimates based upon the magnetic reconnection observed in the simulations to derive a ''propellor'' spindown torque on B, which is the dominant mode of angular mementum extraction from this star. Application of this torque to B's observed spindown yields a polar dipole field ∼ 7 x 10 11 Gauss (magnetic moment (micro) B ∼ 3.5 x 10 29 cgs). This torque has a braking index of unity. We show that the model can explain the known eclipses only if the A wind's density is at least 4 orders of magnitude greater than is expected from existing popular models of pair creation in pulsars. We discuss the implications of this result for our general understanding of pulsar physics

Separated before birth: pulsars B2020+28 and B2021+51 as the remnants of runaway stars

Science.gov (United States)

Gvaramadze, V. V.

2007-08-01

Astrometric data on the pulsars B2020+28 and B2021+51 suggest that they originated within several parsecs of each other in the direction of the Cyg OB2 association. It was proposed that the pulsars share their origin in a common massive binary and were separated at the birth of the second pulsar following the asymmetric supernova explosion. We consider a different scenario for the origin of the pulsar pair based on a possibility that the pulsars were separated before their birth and that they are the remnants of runaway stars ejected (with velocities similar to those of the pulsars) from the core of Cyg OB2 due to strong three- or four-body dynamical encounters. Our scenario does not require any asymmetry in supernova explosions.

Magnetar-like X-Ray Bursts Suppress Pulsar Radio Emission

Energy Technology Data Exchange (ETDEWEB)

Archibald, R. F.; Lyutikov, M.; Kaspi, V. M.; Tendulkar, S. P. [Department of Physics and McGill Space Institute, McGill University, 3600 University Street, Montreal, QC H3A 2T8 (Canada); Burgay, M.; Possenti, A. [INAF–Osservatorio Astronomico di Cagliari, Via della Scienza 5, I-09047 Selargius (Italy); Esposito, P.; Rea, N. [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Israel, G. [INAF–Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone, Roma (Italy); Kerr, M. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Sarkissian, J. [CSIRO Astronomy and Space Science, Parkes Observatory, P.O. Box 276, Parkes, NSW 2870 (Australia); Scholz, P., E-mail: archibald@astro.utoronto.ca [National Research Council of Canada, Herzberg Astronomy and Astrophysics, Dominion Radio Astrophysical Observatory, P.O. Box 248, Penticton, BC V2A 6J9 (Canada)

2017-11-10

Rotation-powered pulsars and magnetars are two different observational manifestations of neutron stars: rotation-powered pulsars are rapidly spinning objects that are mostly observed as pulsating radio sources, while magnetars, neutron stars with the highest known magnetic fields, often emit short-duration X-ray bursts. Here, we report simultaneous observations of the high-magnetic-field radio pulsar PSR J1119−6127 at X-ray, with XMM-Newton and NuSTAR , and at radio energies with the Parkes radio telescope, during a period of magnetar-like bursts. The rotationally powered radio emission shuts off coincident with the occurrence of multiple X-ray bursts and recovers on a timescale of ∼70 s. These observations of related radio and X-ray phenomena further solidify the connection between radio pulsars and magnetars and suggest that the pair plasma produced in bursts can disrupt the acceleration mechanism of radio-emitting particles.

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.;

A METAL-RICH LOW-GRAVITY COMPANION TO A MASSIVE MILLISECOND PULSAR

International Nuclear Information System (INIS)

Kaplan, D. L.; Bhalerao, V. B.; Van Kerkwijk, M. H.; Koester, D.; Kulkarni, S. R.; Stovall, K.

2013-01-01

Most millisecond pulsars with low-mass companions are in systems with either helium-core white dwarfs or non-degenerate (''black widow'' or ''redback'') stars. A candidate counterpart to PSR J1816+4510 was identified by Kaplan et al. whose properties were suggestive of both types of companions although identical to neither. We have assembled optical spectroscopy of the candidate companion and confirm that it is part of the binary system with a radial velocity amplitude of 343 ± 7 km s –1 , implying a high pulsar mass, M psr sin 3 i = 1.84 ± 0.11 M ☉ , and a companion mass M c sin 3 i = 0.193 ± 0.012 M ☉ , where i is the inclination of the orbit. The companion appears similar to proto-white dwarfs/sdB stars, with a gravity log 10 (g) = 4.9 ± 0.3, and effective temperature 16, 000 ± 500 K. The strongest lines in the spectrum are from hydrogen, but numerous lines from helium, calcium, silicon, and magnesium are present as well, with implied abundances of roughly 10 times solar (relative to hydrogen). As such, while from the spectrum the companion to PSR J1816+4510 is superficially most similar to a low-mass white dwarf, it has much lower gravity, is substantially larger, and shows substantial metals. Furthermore, it is able to produce ionized gas eclipses, which had previously been seen only for low-mass, non-degenerate companions in redback or black widow systems. We discuss the companion in relation to other sources, but find that we understand neither its nature nor its origins. Thus, the system is interesting for understanding unusual stellar products of binary evolution, as well as, independent of its nature, for determining neutron-star masses.

NATURE OF CYCLICAL CHANGES IN THE TIMING RESIDUALS FROM THE PULSAR B1642 - 03

International Nuclear Information System (INIS)

Shabanova, T. V.

2009-01-01

We report an analysis of timing data for the pulsar B1642-03 (J1645 - 0317) gathered over the 40-year time span between 1969 and 2008. During this interval, the pulsar experienced eight glitch-like events with a fractional increase in the rotation frequency Δν/ν ∼ (0.9-2.6) x 10 -9 . We have revealed two important relations in the properties of these peculiar glitches. The first result shows that there is a strong linear correlation between the amplitude of the glitch and the time interval to the next glitch with a slope of about 0.0026 x 10 -9 Hz day -1 . This relation allows us to predict epochs of new glitches. The second result shows that the amplitude of the glitches is modulated by a periodic large-scale sawtooth-like function. As a result of this modulation, the glitch amplitude varies discretely from glitch to glitch with a step of 1.5 x 10 -9 Hz in the range (2.4-6.9) x 10 -9 Hz. The post-glitch time interval also varies discretely with a step of ∼ 600 days in the range 900-2700 days. An analysis of the data showed that three modulation schemes with modulation periods of 43 years, 53 years, and 60 years are possible. The best model is the 60-year modulation scheme including 12 glitches. We make a conclusion that the nature of the observed cyclical changes in the timing residuals from PSR B1642 - 03 is a continuous generation of peculiar glitches whose amplitudes are modulated by a periodic large-scale sawtooth-like function. As the modulation function is periodical, the picture of cyclical timing residuals will be exactly repeated in each modulation period or every 60 years.

A high-frequency survey of the southern Galactic plane for pulsars

Science.gov (United States)

Johnston, Simon; Lyne, A. G.; Manchester, R. N.; Kniffen, D. A.; D'Amico, N.; Lim, J.; Ashworth, M.

1992-01-01

Results of an HF survey designed to detect young, distant, and short-period pulsars are presented. The survey detected a total of 100 pulsars, 46 of which were previously unknown. The periods of the newly discovered pulsars range between 47 ms and 2.5 ms. One of the new discoveries, PSR 1259-63, is a member of a long-period binary system. At least three of the pulsars have ages less than 30,000 yr, bringing the total number of such pulsars to 12. The majority of the new discoveries are distant objects with high dispersion measures, which are difficult to detect at low frequencies. This demonstrates that the survey has reduced the severe selection effects of pulse scattering, high Galactic background temperature, and dispersion broadening, which hamper the detection of such pulsars at low radio frequencies. The pulsar distribution in the southern Galaxy is found to extend much further from the Galactic center than that in the north, probably due to two prominent spiral arms in the southern Galaxy.

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.

Pulsar spin-down: the glitch-dominated rotation of PSR J0537-6910

Science.gov (United States)

Antonopoulou, D.; Espinoza, C. M.; Kuiper, L.; Andersson, N.

2018-01-01

The young, fast-spinning X-ray pulsar J0537-6910 displays an extreme glitch activity, with large spin-ups interrupting its decelerating rotation every ∼100 d. We present nearly 13 yr of timing data from this pulsar, obtained with the Rossi X-ray Timing Explorer. We discovered 22 new glitches and performed a consistent analysis of all 45 glitches detected in the complete data span. Our results corroborate the previously reported strong correlation between glitch spin-up size and the time to the next glitch, a relation that has not been observed so far in any other pulsar. The spin evolution is dominated by the glitches, which occur at a rate of ∼3.5 per year, and the post-glitch recoveries, which prevail the entire interglitch intervals. This distinctive behaviour provides invaluable insights into the physics of glitches. The observations can be explained with a multicomponent model that accounts for the dynamics of the neutron superfluid present in the crust and core of neutron stars. We place limits on the moment of inertia of the component responsible for the spin-up and, ignoring differential rotation, the velocity difference it can sustain with the crust. Contrary to its rapid decrease between glitches, the spin-down rate increased over the 13 yr, and we find the long-term braking index nl = -1.22(4), the only negative braking index seen in a young pulsar. We briefly discuss the plausible interpretations of this result, which is in stark contrast to the predictions of standard models of pulsar spin-down.

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.

Asymmetric supernova explosions and the origin of binary pulsars

International Nuclear Information System (INIS)

Sutantyo, W.

1978-01-01

The author investigates the effect of asymmetric supernova explosions on the orbital parameters of binary systems with a compact component. Such explosions are related to the origin of binary pulsars. The degree of asymmetry of the explosion is represented by the kick velocity gained by the exploding star due to the asymmetric mass ejection. The required kick velocity to produce the observed parameters of the binary pulsar PSR 1913 + 16 should be larger than approximately 80 km s -1 if the mass of the exploding star is larger than approximately 4 solar masses. The mean survival probability of the binary system ( ) is examined for various degrees of asymmetry in the explosion. The rare occurrence of a binary pulsar does not neccessarily imply that such a probability is low since not all pulsars have originated in a binary system. Assuming the birth rate of pulsars by Taylor and Manchester (1977), it is derived that would be as high as 0.25. Such values of can be obtained if the mass of the exploding stars is, in general, not large (< approximately 10 solar masses). (Auth.)

The largest glitch observed in the Crab pulsar

Science.gov (United States)

Shaw, B.; Lyne, A. G.; Stappers, B. W.; Weltevrede, P.; Bassa, C. G.; Lien, A. Y.; Mickaliger, M. B.; Breton, R. P.; Jordan, C. A.; Keith, M. J.; Krimm, H. A.

2018-05-01

We have observed a large glitch in the Crab pulsar (PSR B0531+21). The glitch occurred around MJD 58064 (2017 November 8) when the pulsar underwent an increase in the rotation rate of Δν = 1.530 × 10-5 Hz, corresponding to a fractional increase of Δν/ν = 0.516 × 10-6 making this event the largest glitch ever observed in this source. Due to our high-cadence and long-dwell time observations of the Crab pulsar we are able to partially resolve a fraction of the total spin-up of the star. This delayed spin-up occurred over a timescale of ˜1.7 days and is similar to the behaviour seen in the 1989 and 1996 large Crab pulsar glitches. The spin-down rate also increased at the glitch epoch by Δ \\dot{ν } / \\dot{ν } = 7 × 10^{-3}. In addition to being the largest such event observed in the Crab, the glitch occurred after the longest period of glitch inactivity since at least 1984 and we discuss a possible relationship between glitch size and waiting time. No changes to the shape of the pulse profile were observed near the glitch epoch at 610 MHz or 1520 MHz, nor did we identify any changes in the X-ray flux from the pulsar. The long-term recovery from the glitch continues to progress as \\dot{ν } slowly rises towards pre-glitch values. In line with other large Crab glitches, we expect there to be a persistent change to \\dot{ν }. We continue to monitor the long-term recovery with frequent, high quality observations.

Einstein@Home DISCOVERY OF A PALFA MILLISECOND PULSAR IN AN ECCENTRIC BINARY ORBIT

Energy Technology Data Exchange (ETDEWEB)

Knispel, B.; Allen, B. [Leibniz Universität, Hannover, D-30167 Hannover (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); Freire, P. C. C.; Lazarus, P. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Aulbert, C.; Bock, O.; Eggenstein, H.-B.; Fehrmann, H. [Max-Planck-Institut für Gravitationsphysik, Callinstr. 38, D-30167 Hannover (Germany); Bogdanov, S.; Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Brazier, A.; Chatterjee, S.; Cordes, J. M. [Department of Astronomy and Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States); Cardoso, F. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Crawford, F. [Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003 (United States); Deneva, J. S. [National Research Council, resident at the Naval Research Laboratory, Washington, DC 20375 (United States); Ferdman, R. [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Hessels, J. W. T., E-mail: benjamin.knispel@aei.mpg.de [ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); and others

2015-06-10

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{sub ⊙} and is most likely a white dwarf (WD). Fully recycled MSPs like this one are thought to be old neutron stars spun-up by mass transfer from a companion star. This process should circularize the orbit, as is observed for the vast majority of binary MSPs, which predominantly have orbital eccentricities e < 0.001. However, four recently discovered binary MSPs have orbits with 0. 027 < e < 0.44; PSR J1950+2414 is the fifth such system to be discovered. The upper limits for its intrinsic spin period derivative and inferred surface magnetic field strength are comparable to those of the general MSP population. The large eccentricities are incompatible with the predictions of the standard recycling scenario: something unusual happened during their evolution. Proposed scenarios are (a) initial evolution of the pulsar in a triple system which became dynamically unstable, (b) origin in an exchange encounter in an environment with high stellar density, (c) rotationally delayed accretion-induced collapse of a super-Chandrasekhar WD, and (d) dynamical interaction of the binary with a circumbinary disk. We compare the properties of all five known eccentric MSPs with the predictions of these formation channels. Future measurements of the masses and proper motion might allow us to firmly exclude some of the proposed formation scenarios.

A 110-ms pulsar, with negative period derivative, in the globular cluster M15

Science.gov (United States)

Wolszczan, A.; Kulkarni, S. R.; Middleditch, J.; Backer, D. C.; Fruchter, A. S.; Dewey, R. J.

1989-01-01

The discovery of a 110-ms pulsar, PSR2127+11, in the globular cluster M15, is reported. The results of nine months of timing measurements place the new pulsar about 2 arcsec from the center of the cluster, and indicate that it is not a member of a close binary system. The measured negative value of the period derivative is probably the result of the pulsar being bodily accelerated in our direction by the gravitational field of the collapsed core of M15. This apparently overwhelms a positive contribution to the period derivative due to magnetic braking. Although the pulsar has an unexpectedly long period, it is argued that it belongs to the class of 'recycled' pulsars, which have been spun up by accretion in a binary system. The subsequent loss of the pulsar's companion is probably due to disruption of the system by close encounters with other stars.

An x-ray nebula associated with the millisecond pulsar B1957+20.

Science.gov (United States)

Stappers, B W; Gaensler, B M; Kaspi, V M; van der Klis, M; Lewin, W H G

2003-02-28

We have detected an x-ray nebula around the binary millisecond pulsar B1957+20. A narrow tail, corresponding to the shocked pulsar wind, is seen interior to the known Halpha bow shock and proves the long-held assumption that the rotational energy of millisecond pulsars is dissipated through relativistic winds. Unresolved x-ray emission likely represents the shock where the winds of the pulsar and its companion collide. This emission indicates that the efficiency with which relativistic particles are accelerated in the postshock flow is similar to that for young pulsars, despite the shock proximity and much weaker surface magnetic field of this millisecond pulsar.

Discovery of an optical bow-shock around pulsar B0740-28

OpenAIRE

Jones, D.H.; Stappers, B.W.; Gaensler, B.M.

2002-01-01

We report the discovery of a faint H-alpha pulsar wind nebula (PWN) powered by the radio pulsar B0740-28. The characteristic bow-shock morphology of the PWN implies a direction of motion consistent with the previously measured velocity vector for the pulsar. The PWN has a flux density more than an order of magnitude lower than for the PWNe seen around other pulsars, but, for a distance 2 kpc, it is consistent with propagation through a medium of atomic density n_H ~ 0.25 cm^{-3}, and neutral ...

A 1.05 M☉ companion to PSR J2222–0137: The coolest known white dwarf?

International Nuclear Information System (INIS)

Kaplan, David L.; Boyles, Jason; McLaughlin, Maura A.; Lorimer, Duncan R.; Dunlap, Bart H.; Tendulkar, Shriharsh P.; Deller, Adam T.; Ransom, Scott M.; Stairs, Ingrid H.

2014-01-01

The recycled pulsar PSR J2222–0137 is one of the closest known neutron stars (NSs) with a parallax distance of 267 −0.9 +1.2 pc and an edge-on orbit. We measure the Shapiro delay in the system through pulsar timing with the Green Bank Telescope, deriving a low pulsar mass (1.20 ± 0.14 M ☉ ) and a high companion mass (1.05 ± 0.06 M ☉ ) consistent with either a low-mass NS or a high-mass white dwarf. We can largely reject the NS hypothesis on the basis of the system's extremely low eccentricity (3 × 10 –4 )—too low to have been the product of two supernovae under normal circumstances. However, despite deep optical and near-infrared searches with Southern Astrophysical Research and the Keck telescopes we have not discovered the optical counterpart of the system. This is consistent with the white dwarf hypothesis only if the effective temperature is <3000 K, a limit that is robust to distance, mass, and atmosphere uncertainties. This would make the companion to PSR J2222–0137 one of the coolest white dwarfs ever observed. For the implied age to be consistent with the age of the Milky Way requires the white dwarf to have already crystallized and entered the faster Debye-cooling regime.

Gamma ray emission from pulsars

International Nuclear Information System (INIS)

Salvati, M.; Massaro, E.

1978-01-01

A model for the production of gamma rays in a pulsar environment is presented, together with numerical computations fitted to the observations of PSR 0833-45. It is assumed that the primary particles are accelerated close to the star surface and then injected along the open field lines, which cause them to emit curvature radiation. The equation describing the particles' braking is integrated exactly up to the first order in the pulsar rotational frequency, and the transfer problem for the curvature photons is solved with the aberration, the Doppler shif, and the pair production absorption being taken into account. The latter effect is due not only to the transverse component of the magnetic field, but also to the electric field induced by the rotation. The synchrotron radiation emitted by the secondary particles is also included, subject to the 'on-the-spot' approximation. It is found that the observed gamma rays originate in the innermost regions of the magnetosphere, where the open lines' bundle is narrow and the geometrical beaming is effective. As shown by the computed pulse profiles, the duty cycle turns out to be equal to a few percent, comparable to the one of PSR 0833-45. The averaged spectra indicate that a substantial fraction of the primary photons do outlive the interaction with the magnetisphere; furthermore, the agreement in shape with the observational curves suggests that the acceleration output is fiarly close to a monoenergetic beam of particles. (orig.) [de

PULSED GAMMA RAYS FROM THE MILLISECOND PULSAR J0030+0451 WITH THE FERMI LARGE AREA TELESCOPE

International Nuclear Information System (INIS)

Abdo, A. A.; Ackermann, M.; Bechtol, K.; Berenji, B.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Axelsson, M.; Battelino, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bonamente, E.; Brigida, M.; Bruel, P.

2009-01-01

We report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar (MSP) PSR J0030+0451 with the Large Area Telescope on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second MSP 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 E-dot=3.5x10 33 erg s -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, 0.07 ± 0.01 and 0.08 ± 0.02 wide, respectively, 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 cutoff 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 -8 cm -2 s -1 with cutoff energy (1.7 ± 0.4 ± 0.5) GeV. Based on its parallax distance of (300 ± 90) pc, we obtain a gamma-ray efficiency L γ /E-dot≅15 percent for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.

Discovery of a Synchrotron Bubble Associated with PSR J1015–5719

Energy Technology Data Exchange (ETDEWEB)

Ng, C.-Y. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Bandiera, R. [Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Hunstead, R. W. [Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006 (Australia); Johnston, S., E-mail: ncy@bohr.physics.hku.hk [CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710 (Australia)

2017-06-20

We report the discovery of a synchrotron nebula, G283.1−0.59, associated with PSR J1015−5719. Radio observations using the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array at 36, 16, 6, and 3 cm reveal a complex morphology. The pulsar is embedded in the “head” of the nebula with fan-shaped diffuse emission. This is connected to a circular bubble of 20″ radius and a collimated tail extending over 1′. Polarization measurements show a highly ordered magnetic field in the nebula. It wraps around the edge of the head and shows an azimuthal configuration near the pulsar, then switches direction quasi-periodically near the bubble and in the tail. Together with the flat radio spectrum observed, we suggest that this system is most plausibly a pulsar wind nebula (PWN), with the head as a bow shock that has a low Mach number and the bubble as a shell expanding in a dense environment. The bubble could act as a magnetic bottle trapping the relativistic particles. A comparison with other bow-shock PWNe with higher Mach numbers shows similar structure and B -field geometry, implying that pulsar velocity may not be the most critical factor in determining the properties of these systems. We also derive analytic expressions for the projected standoff distance and shape of an inclined bow shock. It is found that the projected distance is always larger than the true distance in three dimensions. On the other hand, the projected shape is not sensitive to the inclination after rescaling with the projected standoff distance.

Discovery of a Synchrotron Bubble Associated with PSR J1015–5719

International Nuclear Information System (INIS)

Ng, C.-Y.; Bandiera, R.; Hunstead, R. W.; Johnston, S.

2017-01-01

We report the discovery of a synchrotron nebula, G283.1−0.59, associated with PSR J1015−5719. Radio observations using the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array at 36, 16, 6, and 3 cm reveal a complex morphology. The pulsar is embedded in the “head” of the nebula with fan-shaped diffuse emission. This is connected to a circular bubble of 20″ radius and a collimated tail extending over 1′. Polarization measurements show a highly ordered magnetic field in the nebula. It wraps around the edge of the head and shows an azimuthal configuration near the pulsar, then switches direction quasi-periodically near the bubble and in the tail. Together with the flat radio spectrum observed, we suggest that this system is most plausibly a pulsar wind nebula (PWN), with the head as a bow shock that has a low Mach number and the bubble as a shell expanding in a dense environment. The bubble could act as a magnetic bottle trapping the relativistic particles. A comparison with other bow-shock PWNe with higher Mach numbers shows similar structure and B -field geometry, implying that pulsar velocity may not be the most critical factor in determining the properties of these systems. We also derive analytic expressions for the projected standoff distance and shape of an inclined bow shock. It is found that the projected distance is always larger than the true distance in three dimensions. On the other hand, the projected shape is not sensitive to the inclination after rescaling with the projected standoff distance.

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.

Search for gravitational waves associated with the August 2006 timing glitch of the Vela pulsar

International Nuclear Information System (INIS)

Abadie, J.; Abbott, B. P.; Abbott, R.; Adhikari, R.; Ajith, P.; Anderson, S. B.; Araya, M.; Aso, Y.; Ballmer, S.; Betzwieser, J.; Billingsley, G.; Black, E.; Blackburn, J. K.; Bork, R.; Brooks, A. F.; Cannon, K. C.; Cardenas, L.; Cepeda, C.; Chalermsongsak, T.; Chatterji, S.

2011-01-01

The physical mechanisms responsible for pulsar timing glitches are thought to excite quasinormal mode oscillations in their parent neutron star that couple to gravitational-wave emission. In August 2006, a timing glitch was observed in the radio emission of PSR B0833-45, the Vela pulsar. At the time of the glitch, the two colocated Hanford gravitational-wave detectors of the Laser Interferometer Gravitational-wave observatory (LIGO) were operational and taking data as part of the fifth LIGO science run (S5). We present the first direct search for the gravitational-wave emission associated with oscillations of the fundamental quadrupole mode excited by a pulsar timing glitch. No gravitational-wave detection candidate was found. We place Bayesian 90% confidence upper limits of 6.3x10 -21 to 1.4x10 -20 on the peak intrinsic strain amplitude of gravitational-wave ring-down signals, depending on which spherical harmonic mode is excited. The corresponding range of energy upper limits is 5.0x10 44 to 1.3x10 45 erg.

Confirming the nature of the knot near the pulsar B1951+32

Science.gov (United States)

Zyuzin, D. A.; Shibanov, Yu A.; Pavlov, G. G.; Danilenko, A. A.

2017-12-01

The energetic and fast-moving radio and γ-ray pulsar B1951+32 is associated with the supernova remnant CTB 80. It powers a complex pulsar wind nebula detected in the radio, Hα and X-rays (Moon et al 2004 ApJ 610 L33). A puzzling optical knot was detected about 0″.5 from the pulsar in the optical and near-IR (Moon et al 2004 ApJ 610 L33; Hester 2000 Bulletin of the AAS 32 1542). It is reminiscent of the unique “inner optical knot” located 0″.6 from the Crab pulsar. Until now there has been no evidence that B1951+32 knot is indeed associated with the pulsar. We observed the pulsar field with the Gemini-North telescope in 2016 to check the association. We performed first near-IR high spatial resolution imaging in the K s band using the NIRI+Altair instrument and deep optical imaging in the gr bands using the GMOS instrument. Our observations showed that the current knot position is shifted by ≈ 0″.6 from the position measured with the HST in 1997. This is consistent with the known pulsar proper motion and is direct evidence of the pulsar-knot connection. We compared the spectral energy distribution of the knot emission with that of the Crab knot. Possible implications of the results are discussed.

The First Continuous Optical Monitoring of the Transitional Millisecond Pulsar PSR J1023+0038 with Kepler

Science.gov (United States)

Papitto, A.; Rea, N.; Coti Zelati, F.; de Martino, D.; Scaringi, S.; Campana, S.; de Ońa Wilhelmi, E.; Knigge, C.; Serenelli, A.; Stella, L.; Torres, D. F.; D’Avanzo, P.; Israel, G. L.

2018-05-01

We report on the first continuous, 80-day optical monitoring of the transitional millisecond pulsar PSR J1023+0038 carried out in mid 2017 with Kepler in the K2 configuration, when an X-ray subluminous accretion disk was present in the binary. Flares lasting from minutes to 14 hr were observed for 15.6% of the time, which is a larger fraction than previously reported on the basis of X-ray and past optical observations, and more frequently when the companion was at superior conjunction of the orbit. A sinusoidal modulation at the binary orbital period was also present with an amplitude of ≃16%, which varied by a few percent over timescales of days, and with a maximum that took place 890 ± 85 s earlier than the superior conjunction of the donor. We interpret this phenomena in terms of reprocessing of the X-ray emission by an asymmetrically heated companion star surface and/or a non-axisymmetric outflow possibly launched close to the inner Lagrangian point. Furthermore, the non-flaring average emission varied by up to ≈40% over a timescale of days in the absence of correspondingly large variations of the irradiating X-ray flux. The latter suggests that the observed changes in the average optical luminosity might be due to variations of the geometry, size, and/or mass accretion rate in the outer regions of the accretion disk.

FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA-X PULSAR WIND NEBULA

International Nuclear Information System (INIS)

Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bonamente, E.; Brigida, M.; Bruel, P.

2010-01-01

We report on gamma-ray observations in the off-pulse window of the Vela pulsar PSR B0833-45 using 11 months of survey data from the Fermi Large Area Telescope (LAT). This pulsar is located in the 8 deg. diameter Vela supernova remnant, which contains several regions of non-thermal emission detected in the radio, X-ray, and gamma-ray bands. The gamma-ray emission detected by the LAT lies within one of these regions, the 2 deg. x 3 deg. area south of the pulsar known as Vela-X. The LAT flux is significantly spatially extended with a best-fit radius of 0. 0 88 ± 0. 0 12 for an assumed radially symmetric uniform disk. The 200 MeV to 20 GeV LAT spectrum of this source is well described by a power law with a spectral index of 2.41 ± 0.09 ± 0.15 and integral flux above 100 MeV of (4.73 ± 0.63 ± 1.32) x 10 -7 cm -2 s -1 . The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses give strong constraints on the energetics and magnetic field of the pulsar wind nebula system and favor a scenario with two distinct electron populations.

Pulsar searches of Fermi unassociated sources with the Effelsberg telescope

International Nuclear Information System (INIS)

Barr, E. D.; Guillemot, L.; Champion, D. J.; Kramer, M.; Eatough, R. P.

2012-01-01

Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated γ-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published in the 1FGL catalogue (Abdo et al. 2010a). In addition, 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 ~0.0137M⊙, 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. Lastly, the reasons behind the seemingly low yield of discoveries are also discussed.

Interaction of a pulsar with interstellar matter

Science.gov (United States)

Istomin, Ya. N.

1994-03-01

An increase of the rate of spin-down dot-P and emergence of a Magnus force acting on the star is connected with the appearance of a dense hydrogen plasma in the region of light surface. These effects are proportional to the permittivity epsilon = 1 + c2/(VA)2, where vA is the Alfven velocity in the vicinity of the light cylinder. During its lifetime, a pulsar can change the direction of its proper velocity and leave the Galactic plane. For the pulsar PSR 1757-24 located in the nebula G5.4-1.2, it is shown that due to the changing value of dot-P its characteristic age increases up to 7.5 x 104 years and the proper velocity decreases in magnitude to the order of 400km/s.

X-RAY PULSATIONS FROM THE RADIO-QUIET GAMMA-RAY PULSAR IN CTA 1

International Nuclear Information System (INIS)

Caraveo, P. A.; De Luca, A.; Marelli, M.; Bignami, G. F.; Ray, P. S.; Saz Parkinson, P. M.; Kanbach, G.

2010-01-01

Prompted by the Fermi-LAT discovery of a radio-quiet gamma-ray pulsar inside the CTA 1 supernova remnant, we obtained a 130 ks XMM-Newton observation to assess the timing behavior of this pulsar. Exploiting both the unprecedented photon harvest and the contemporary Fermi-LAT timing measurements, a 4.7σ single-peak pulsation is detected, making PSR J0007+7303 the second example, after Geminga, of a radio-quiet gamma-ray pulsar also seen to pulsate in X-rays. Phase-resolved spectroscopy shows that the off-pulse portion of the light curve is dominated by a power-law, non-thermal spectrum, while the X-ray peak emission appears to be mainly of thermal origin, probably from a polar cap heated by magnetospheric return currents, pointing to a hot spot varying throughout the pulsar rotation.

Pair plasma in pulsar magnetospheres

International Nuclear Information System (INIS)

Asseo, Estelle

2003-01-01

The main features of radiation received from pulsars imply that they are neutron stars which contain an extremely intense magnetic field and emit coherently in the radio domain. Most recent studies attribute the origin of the coherence to plasma instabilities arising in pulsar magnetospheres; they mainly concern the linear, or the nonlinear, character of the involved unstable waves. We briefly introduce radio pulsars and specify physical conditions in pulsar emission regions: geometrical properties, magnetic field, pair creation processes and repartition of relativistic charged particles. We point to the main ingredients of the linear theory, extensively explored since the 1970s: (i) a dispersion relation specific to the pulsar case; (ii) the characteristics of the waves able to propagate in relativistic pulsar plasmas; (iii) the different ways in which a two-humped distribution of particles may arise in a pulsar magnetosphere and favour the development of a two-stream instability. We sum up recent improvements of the linear theory: (i) the determination of a 'coupling function' responsible for high values of the wave field components and electromagnetic energy available; (ii) the obtention of new dispersion relations for actually anisotropic pulsar plasmas with relativistic motions and temperatures; (iii) the interaction between a plasma and a beam, both with relativistic motions and temperatures; (iv) the interpretation of observed 'coral' and 'conal' features, associated with the presence of boundaries and curved magnetic field lines in the emission region; (v) the detailed topology of the magnetic field in the different parts of the emission region and its relation to models recently proposed to interpret drifting subpulses observed from PSR 0943+10, showing 20 sub-beams of emission. We relate the nonlinear evolution of the two-stream instability and development of strong turbulence in relativistic pulsar plasmas to the emergence of relativistic solitons, able

POLARIZATION OBSERVATIONS OF 100 PULSARS AT 774 MHz BY THE GREEN BANK TELESCOPE

International Nuclear Information System (INIS)

Han, J. L.; Demorest, P. B.; Van Straten, W.; Lyne, A. G.

2009-01-01

We report on polarimetric observations of 100 pulsars centered on 774 MHz, made using the Green Bank Telescope, presenting their polarization profiles and polarized flux densities and comparing them with previous observations when possible. For 67 pulsars, these are the first such measurements made. Polarization profiles of 8 millisecond-pulsars in our sample show wide profiles and flat position-angle curves. Strong linear polarization, sometimes approaching 100% of the total intensity, has been detected in all or a part of the average pulse profiles of some pulsars. In general, circular polarization is very weak, although it is observed to be extremely strong in the leading component of PSR J1920+2650. Sense reversal of circular polarization as a function of pulse phase has been detected from both core and other components of more than 20 pulsars. Any relationship between the spin-down luminosity and the percentage of linear polarization is not evident in our data at this frequency.

A 1.05 M{sub ☉} companion to PSR J2222–0137: The coolest known white dwarf?

Energy Technology Data Exchange (ETDEWEB)

Kaplan, David L. [Department of Physics, University of Wisconsin-Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States); Boyles, Jason; McLaughlin, Maura A.; Lorimer, Duncan R. [Department of Physics and Astronomy, West Virginia University, White Hall, Box 6315, Morgantown, WV 26506-6315 (United States); Dunlap, Bart H. [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255 (United States); Tendulkar, Shriharsh P. [Space Radiation Laboratory, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Deller, Adam T. [ASTRON, P.O. Box 2, 7990 AA Dwingeloo (Netherlands); Ransom, Scott M. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Stairs, Ingrid H., E-mail: kaplan@uwm.edu [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1 (Canada)

2014-07-10

The recycled pulsar PSR J2222–0137 is one of the closest known neutron stars (NSs) with a parallax distance of 267{sub −0.9}{sup +1.2} pc and an edge-on orbit. We measure the Shapiro delay in the system through pulsar timing with the Green Bank Telescope, deriving a low pulsar mass (1.20 ± 0.14 M{sub ☉}) and a high companion mass (1.05 ± 0.06 M{sub ☉}) consistent with either a low-mass NS or a high-mass white dwarf. We can largely reject the NS hypothesis on the basis of the system's extremely low eccentricity (3 × 10{sup –4})—too low to have been the product of two supernovae under normal circumstances. However, despite deep optical and near-infrared searches with Southern Astrophysical Research and the Keck telescopes we have not discovered the optical counterpart of the system. This is consistent with the white dwarf hypothesis only if the effective temperature is <3000 K, a limit that is robust to distance, mass, and atmosphere uncertainties. This would make the companion to PSR J2222–0137 one of the coolest white dwarfs ever observed. For the implied age to be consistent with the age of the Milky Way requires the white dwarf to have already crystallized and entered the faster Debye-cooling regime.

Modeling Phase-Aligned Gamma-Ray and Radio Millisecond Pulsar Light Curves

Science.gov (United States)

Venter, C.; Johnson, T.; Harding, A.

2012-01-01

Since the discovery of the first eight gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope, this population has been steadily expanding. Four of the more recent detections, PSR J00340534, PSR J1939+2134 (B1937+21; the first MSP ever discovered), PSR J1959+2048 (B1957+20; the first discovery of a black widow system), and PSR J2214+3000, exhibit a phenomenon not present in the original discoveries: nearly phase-aligned radio and gamma-ray light curves (LCs). To account for the phase alignment, we explore models where both the radio and gamma-ray emission originate either in the outer magnetosphere near the light cylinder or near the polar caps. Using a Markov Chain Monte Carlo technique to search for best-fit model parameters, we obtain reasonable LC fits for the first three of these MSPs in the context of altitude-limited outer gap (alOG) and two-pole caustic (alTPC) geometries (for both gamma-ray and radio emission). These models differ from the standard outer gap (OG)/two-pole caustic (TPC) models in two respects: the radio emission originates in caustics at relatively high altitudes compared to the usual conal radio beams, and we allow both the minimum and maximum altitudes of the gamma-ray and radio emission regions to vary within a limited range (excluding the minimum gamma-ray altitude of the alTPC model, which is kept constant at the stellar radius, and that of the alOG model, which is set to the position-dependent null charge surface altitude). Alternatively, phase-aligned solutions also exist for emission originating near the stellar surface in a slot gap scenario (low-altitude slot gap (laSG) models). We find that the alTPC models provide slightly better LC fits than the alOG models, and both of these give better fits than the laSG models (for the limited range of parameters considered in the case of the laSG models). Thus, our fits imply that the phase-aligned LCs are likely of caustic origin, produced in the outer magnetosphere, and

NuSTAR discovery of a young, energetic pulsar associated with the luminous gamma-ray source Hess J1640-465

DEFF Research Database (Denmark)

Gotthelf, E. V.; Tomsick, J. A.; Halpern, J. P.

2014-01-01

We report the discovery of a 206 ms pulsar associated with the TeV γ-ray source HESS J1640-465 using the Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray observatory. PSR J1640-4631 lies within the shell-type supernova remnant (SNR) G338.3-0.0, and coincides with an X-ray point source...... and putative pulsar wind nebula (PWN) previously identified in XMM-Newton and Chandra images. It is spinning down rapidly with period derivative 9.758(44) × 10-13, yielding a spin-down luminosity 4.4 × 1036 erg s-1, characteristic age 3350 yr, and surface dipole magnetic field strength Bs = 1.4 × 1013 G....... For the measured distance of 12 kpc to G338.3-0.0, the 0.2-10 TeV luminosity of HESS J1640-465 is 6% of the pulsar's present . The Fermi source 1FHL J1640.5-4634 is marginally coincident with PSR J1640-4631, but we find no γ-ray pulsations in a search using five years of Fermi Large Area Telescope (LAT) data...

Journal of Astrophysics and Astronomy | Indian Academy of Sciences

Indian Academy of Sciences (India)

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 ...

MULTIWAVELENGTH OBSERVATIONS OF THE REDBACK MILLISECOND PULSAR J1048+2339

Energy Technology Data Exchange (ETDEWEB)

Deneva, J. S. [National Research Council, resident at the Naval Research Laboratory, Washington, DC 20375 (United States); Ray, P. S.; Wood, K.; Wolff, M. T. [Naval Research Laboratory, Washington, DC 20375 (United States); Camilo, F.; Halpern, J. P. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Cromartie, H. T. [University of Virginia, Charlottesville, VA 22904 (United States); Ferrara, E. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kerr, M. [CSIRO Astronomy and Space Science, Marsfield NSW 2122 (Australia); Ransom, S. M. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Chambers, K. C.; Magnier, E. A. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

2016-06-01

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 -Large Area Telescope source 3FGL J1048.6+2338. Two years of timing allowed us to derive precise astrometric and orbital parameters for the pulsar. PSR J1048+2339 is in a 6 hr binary and exhibits radio eclipses over half the orbital period and rapid orbital period variations. The companion has a minimum mass of 0.3 M {sub ⊙}, and we have identified a V ∼ 20 variable optical counterpart in data from several surveys. The phasing of its ∼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 radio ephemeris.

TIMING OF 29 PULSARS DISCOVERED IN THE PALFA SURVEY

Energy Technology Data Exchange (ETDEWEB)

Lyne, A. G.; Stappers, B. W. [Jodrell Bank Centre for Astrophys., School of Phys. and Astr., Univ. of Manchester, Manch., M13 9PL (United Kingdom); Bogdanov, S. [Columbia Astrophysics Laboratory, Columbia Univ., New York, NY 10027 (United States); Ferdman, R. D.; Kaspi, V. M.; Lynch, R. [Dept. of Physics and McGill Space Institute, McGill Univ., Montreal, QC H3A 2T8 (Canada); Freire, P. C. C.; Lazarus, P. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Knispel, B.; Allen, B. [Max-Planck-Institut für Gravitationsphysik, D-30167 Hannover (Germany); Brazier, A.; Chatterjee, S.; Cordes, J. M. [Dept. of Astronomy, Cornell Univ., Ithaca, NY 14853 (United States); Camilo, F. [SKA South Africa, Pinelands, 7405 (South Africa); Cardoso, F. [Physics Dept., Univ. of Wisconsin—Milwaukee, 3135 N. Maryland Ave., Milwaukee, WI 53211 (United States); Crawford, F. [Dept. of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003 (United States); Deneva, J. S. [National Research Council, resident at the Naval Research Laboratory, Washington, DC 20375 (United States); Hessels, J. W. T.; Leeuwen, J. van [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Jenet, F. A. [Center for Gravitational Wave Astronomy, Univ. Texas—Brownsville, TX 78520 (United States); and others

2017-01-10

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 {sub ⊙}. 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.

Timing properties of PSR 1951 + 32 in the CTB 80 supernova remnant

International Nuclear Information System (INIS)

Foster, R.S.; Backer, D.C.; Wolszczan, A.

1990-01-01

Timing observations of PSR 1951+32, the 39.5 ms pulsar found in the CTB 80 supernova remnant, have detected a spin-up in the rotation rate of the neutron star. The fractional change in the rotational frequency of 2.1 x 10 to the -9th was accompanied by a fractional change in the frequency derivative of -0.00019 which has persisted for 1 yr after the event. Updated VLA astrometric observations of the pulsar are presented. Dispersion measure variations have been measured between 430 MHz and 1400 MHz at the level of 0.02 pc/cu cm. Together, dispersion measure fluctuations and diffractive scintillations indicate a power-law electron density turbulence spectrum on scales sizes between 10 to the 9th and 10 to the 14th cm that may be relevant to cosmic-ray propagation. 34 refs

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.

Inductive Spikes in the Crab Nebula: A Theory of γ-Ray Flares.

Science.gov (United States)

Kirk, John G; Giacinti, Gwenael

2017-11-24

We show that the mysterious, rapidly variable emission at ∼400  MeV observed from the Crab Nebula by the AGILE and Fermi satellites could be the result of a sudden drop in the mass loading of the pulsar wind. The current required to maintain wave activity in the wind is then carried by very few particles of a high Lorentz factor. On impacting the nebula, these particles produce a tightly beamed, high-luminosity burst of hard gamma rays, similar to those observed. This implies that (i) the emission is synchrotron radiation in the toroidal field of the nebula and, therefore, linearly polarized and (ii) this mechanism potentially contributes to the gamma-ray emission from other powerful pulsars, such as the Magellanic Cloud objects J0537-6910 and B0540-69.

Observations of Pulsars with the Fermi Gamma-ray Space Telescope

International Nuclear Information System (INIS)

Parent, D.

2009-11-01

The Large Area Telescope (LAT) on Fermi, launched on 2008 June 11, is a space telescope to explore the high energy γ-ray universe. The instrument covers the energy range from 20 MeV to 300 GeV with greatly improved sensitivity and ability to localize γ-ray point sources. It detects γ-rays through conversion to electron-positron pairs and measurement of their direction in a tracker and their energy in a calorimeter. This thesis presents the γ-ray light curves and the phase-resolved spectral measurements of radio-loud gamma-ray pulsars detected by the LAT. The measurement of pulsar spectral parameters (i.e. integrated flux, spectral index, and energy cut-off) depends on the instrument response functions (IRFs). A method developed for the on-orbit validation of the effective area is presented using the Vela pulsar. The cut efficiencies between the real data and the simulated data are compared at each stage of the background rejection. The results are then propagated to the IRFs, allowing the systematic uncertainties of the spectral parameters to be estimated. The last part of this thesis presents the discoveries, using both the LAT observations and the radio and X ephemeris, of new individual γ-ray pulsars such as PSR J0205+6449, and the Vela-like pulsars J2229+6114 and J1048-5832. Timing and spectral analysis are investigated in order to constrain the γ-ray emission model. In addition, we discuss the properties of a large population of γ-ray pulsars detected by the LAT, including normal pulsars, and millisecond pulsars. (author)

STRUCTURES OF THE VELA PULSAR AND THE GLITCH CRISIS FROM THE BRUECKNER THEORY

International Nuclear Information System (INIS)

Li, A.; Dong, J. M.; Wang, J. B.; Xu, R. X.

2016-01-01

Detailed structures of the Vela pulsar (PSR B0833-45, with a period of 89.33 ms) are predicted by adopting a recently constructed unified treatment of all parts of neutron stars: the outer crust, the inner crust, and the core based on modern microscopic Brueckner–Hartree–Fock calculations. Taking a pulsar mass in the range from 1.0 to 2.0 M ⊙ , we calculate the central density, the core/crust radii, the core/crustal mass, the core/crustal thickness, the moment of inertia, and the crustal moment of inertia. Among them, the crustal moment of inertia could be effectively constrained from the accumulated glitch observations, which has been a great debate recently, known as the “glitch crisis.” Namely, superfluid neutrons contained in the inner crust, which are regarded as the origin of the glitch in the standard two-component model, could be largely entrained in the nuclei lattices, and then there may not be enough superfluid neutrons (∼4/5 less than the previous value) to trigger the large glitches (Δν/ν 0  ∼ 10 −6 ) in the Vela pulsar. By confronting the glitch observations with the theoretical calculations for the crustal moment of inertia, we find that despite some recent opposition to the crisis argument, the glitch crisis is still present, which means that besides the crustal superfluid neutrons, core neutrons might be necessary for explaining the large glitches of the Vela pulsar

COBRA: a Bayesian approach to pulsar searching

Science.gov (United States)

Lentati, L.; Champion, D. J.; Kramer, M.; Barr, E.; Torne, P.

2018-02-01

We introduce COBRA, a GPU-accelerated Bayesian analysis package for performing pulsar searching, that uses candidates from traditional search techniques to set the prior used for the periodicity of the source, and performs a blind search in all remaining parameters. COBRA incorporates models for both isolated and accelerated systems, as well as both Keplerian and relativistic binaries, and exploits pulse phase information to combine search epochs coherently, over time, frequency or across multiple telescopes. We demonstrate the efficacy of our approach in a series of simulations that challenge typical search techniques, including highly aliased signals, and relativistic binary systems. In the most extreme case, we simulate an 8 h observation containing 24 orbits of a pulsar in a binary with a 30 M⊙ companion. Even in this scenario we show that we can build up from an initial low-significance candidate, to fully recovering the signal. We also apply the method to survey data of three pulsars from the globular cluster 47Tuc: PSRs J0024-7204D, J0023-7203J and J0024-7204R. This final pulsar is in a 1.6 h binary, the shortest of any pulsar in 47Tuc, and additionally shows significant scintillation. By allowing the amplitude of the source to vary as a function of time, however, we show that we are able to obtain optimal combinations of such noisy data. We also demonstrate the ability of COBRA to perform high-precision pulsar timing directly on the single pulse survey data, and obtain a 95 per cent upper limit on the eccentricity of PSR J0024-7204R of εb < 0.0007.

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

X-RAY EMISSION FROM J1446–4701, J1311–3430, AND OTHER BLACK WIDOW PULSARS

Energy Technology Data Exchange (ETDEWEB)

Arumugasamy, Prakash; Pavlov, George G. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Garmire, Gordon P., E-mail: pxa151@ucs.psu.edu [Huntingdon Institute for X-ray Astronomy, LLC, 10677 Franks Road, Huntingdon, PA 16652 (United States)

2015-12-01

We present the results of detailed X-ray analysis of two black-widow pulsars (BWPs), J1446–4701 and J1311–3430. PSR J1446–4701 is a BWP with orbital parameters near the median values of the sample of known BWPs. Its X-ray emission that was detected by XMM-Newton is well characterized by a soft power-law (PL) spectrum (photon index Γ ≈ 3), and it shows no significant orbital modulations. In view of a lack of radio eclipses and an optical non-detection, the system most likely has a low orbital inclination. PSR J1311–3430 is an extreme BWP with a very compact orbit and the lowest minimum mass companion. Our Chandra data confirm the hard Γ ≈ 1.3 emission seen in previous observations. Through phase-restricted spectral analysis, we found a hint (∼2.6σ) of spectral hardening around pulsar inferior conjunction. We also provide a uniform analysis of the 12 BWPs observed with Chandra and compare their X-ray properties. Pulsars with soft, Γ > 2.5 emission seem to have lower than average X-ray and γ-ray luminosities. We do not, however, see any other prominent correlation between the pulsar’s X-ray emission characteristics and any of its other properties. The contribution of the intra-binary shock to the total X-ray emission, if any, is not discernible in this sample of pulsars with shallow observations.

Discovery of a Young, Energetic Pulsar Near the Supernova Remnant G290.1-0.8 and the Gamma-Ray Source 2EG J1103-6106

Science.gov (United States)

Kaspi, V. M.; Bailes, M.; Manchester, R. N.; Stappers, B. W.; Sandhu, J.; Navarro, J.; D'Amico, N.

1996-01-01

We report on the discovery and follow-up timing observations of a 63-ms radio pulsar, PSR J1105-6107. We show that the pulsar is young, having a characteristic age of only 63kyr. We consider its possible association with the nearby remnant G290.1-0.8 (MSH 11-61A) but uncertainties in the distances and ages preclude a firm conclusion.

CYCLICAL CHANGES IN THE TIMING RESIDUALS FROM THE PULSAR B0919+06

International Nuclear Information System (INIS)

Shabanova, Tatiana V.

2010-01-01

We report the detection of a large glitch in the pulsar B0919+06 (J0922+0638). The glitch occurred in 2009 November 5 (MJD 55140) and was characterized by a fractional increase in the rotation frequency of Δν/ν ∼ 1.3 x 10 -6 . A large glitch happens in the pulsar whose rotation has an unstable character. We present the results of the analysis of the rotation behavior of this pulsar over the 30 year time span from 1979 to 2009. These results show that the pulsar's rotation frequency underwent continuous, slow oscillations that resembled glitch-like events. During the 1991-2009 interval, the pulsar experienced a continuous sequence of 12 slow glitches with a fractional increase in the rotation frequency of Δν/ν ∼ 1.5 x 10 -9 . All the slow glitches observed have similar signatures related to a slow increase in the rotation frequency for ∼200 days and to the subsequent relaxation back to the pre-glitch value for ∼400 days. We show that a continuous sequence of such slow glitches is characterized by practically identical amplitudes of Δν ∼ 3.5 x 10 -9 Hz and identical time intervals between glitches of ∼600 days and is well described by a periodic sawtooth-like function. The detection of two different phenomena, such as a large glitch and a sequence of slow glitches, indicate the presence of two types of discontinuities in the rotation frequency of the pulsar B0919+06. These discontinuities can be classified as normal and slow glitches.

GAMMA-RAY EMISSION FROM PSR J0007+7303 USING SEVEN YEARS OF FERMI LARGE AREA TELESCOPE OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Li, Jian; Torres, Diego F.; De Oña Wilhelmi, Emma; Rea, Nanda; Martin, Jonatan [Institute of Space Sciences (CSIC–IEEC), Campus UAB, Carrer de Magrans s/n, E-08193 Barcelona (Spain)

2016-11-01

Based on more than seven years of Fermi Large Area Telescope 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 test statistic value of 262 (∼16 σ ). In the description of the off-peak spectrum of PSR J0007+7303, a power law with an exponential cutoff at 2.7 ± 1.2 ± 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 σ . The possible existence of a cutoff hints at a magnetospheric origin of the emission. In addition, no extended gamma-ray emission is detected that is 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 × 10{sup −12} erg cm{sup −2} s{sup −1} in the energy range 10–300 GeV is reported, for an extended source assuming the morphology of the VERITAS detection. During on-peak phases, a sub-exponential cutoff is significantly preferred (∼11 σ ) for representing the spectral energy distribution, in both the phase-averaged and phase-resolved spectra. Three glitches are detected during the observation period and we found no flux variability at the time of the glitches or in the long-term behavior. We also report the discovery of a previously unknown gamma-ray source in the vicinity of PSR J0007+7303, Fermi J0020+7328, which we associate with the z = 1.781 quasar S5 0016+73. A concurrent analysis of this source is needed to correctly characterize the behavior of CTA 1 and it is also presented in the paper.

Discovery of two planets around a millisecond pulsar

Science.gov (United States)

Wolszczan, A.

1992-01-01

By timing the arrival of radio signals from a rapidly spinning pulsar at the Arecibo Observatory's radio/radar telescope, the most convincing evidence so far for a planetary system outside our own has been found: two or possibly three planets that orbit the neutron star called PSR1257+12. This finding indicates that planet formation may be a more common process than previously anticipated and that the formation of disks of gas and dust that are sufficiently massive to condense into Earth-sized planets orbiting their central bodies can take place under surprisingly diverse conditions.

Extreme scattering events towards two young pulsars

Science.gov (United States)

Kerr, M.; Coles, W. A.; Ward, C. A.; Johnston, S.; Tuntsov, A. V.; Shannon, R. M.

2018-03-01

We have measured the scintillation properties of 151 young, energetic pulsars with the Parkes radio telescope and have identified two extreme scattering events (ESEs). Towards PSR J1057-5226, we discovered a 3 yr span of strengthened scattering during which the variability in flux density and the scintillation bandwidth decreased markedly. The transverse size of the scattering region is ˜23 au, and strong flux density enhancement before and after the ESE may arise from refractive focusing. Long observations reveal scintillation arcs characteristic of interference between rays scattered at large angles, and the clearest arcs appear during the ESE. The arcs suggest scattering by a screen 100-200 pc from the Earth, perhaps ionized filamentary structure associated with the boundary of the local bubble(s). Towards PSR J1740-3015, we observed a `double dip' in the measured flux density similar to ESEs observed towards compact extragalactic radio sources. The observed shape is consistent with that produced by a many-au scale diverging plasma lens with electron density ˜500 cm-3. The continuing ESE is at least 1500 d long, making it the longest detected event to date. These detections, with materially different observational signatures, indicate that well-calibrated pulsar monitoring is a keen tool for ESE detection and interstellar medium (ISM) diagnostics. They illustrate the strong role au-scale non-Kolmogorov density fluctuations and the local ISM structure play in such events and are key to understanding both their intrinsic physics and their impact on other phenomena, particularly fast radio bursts.

THE BRAKING INDEX OF A RADIO-QUIET GAMMA-RAY PULSAR

Energy Technology Data Exchange (ETDEWEB)

Clark, C. J.; Pletsch, H. J.; Allen, B.; Aulbert, C.; Beer, C.; Bock, O.; Cuéllar, A.; Eggenstein, H. B.; Fehrmann, H.; Machenschalk, B.; Nieder, L. [Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, D-30167 Hannover (Germany); Wu, J.; Guillemot, L.; Kramer, M. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Camilo, F. [SKA South Africa, Pinelands, 7405 (South Africa); Johnson, T. J. [College of Science, George Mason University, Fairfax, VA 22030 (United States); Kerr, M., E-mail: colin.clark@aei.mpg.de [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping, NSW 1710 (Australia)

2016-11-20

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 μ 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 ± 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 × 10{sup 13} 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.

THE BRAKING INDEX OF A RADIO-QUIET GAMMA-RAY PULSAR

International Nuclear Information System (INIS)

Clark, C. J.; Pletsch, H. J.; Allen, B.; Aulbert, C.; Beer, C.; Bock, O.; Cuéllar, A.; Eggenstein, H. B.; Fehrmann, H.; Machenschalk, B.; Nieder, L.; Wu, J.; Guillemot, L.; Kramer, M.; Camilo, F.; Johnson, T. J.; Kerr, 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 at 1369 MHz of 30 μ 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 ± 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 × 10 13 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.

A transient, flat spectrum radio pulsar near the Galactic Centre

Science.gov (United States)

Dexter, J.; Degenaar, N.; Kerr, M.; Deller, A.; Deneva, J.; Lazarus, P.; Kramer, M.; Champion, D.; Karuppusamy, R.

2017-06-01

Recent studies have shown possible connections between highly magnetized neutron stars ('magnetars'), whose X-ray emission is too bright to be powered by rotational energy, and ordinary radio pulsars. In addition to the magnetar SGR J1745-2900, one of the radio pulsars in the Galactic Centre (GC) region, PSR J1746-2850, had timing properties implying a large magnetic field strength and young age, as well as a flat spectrum. All characteristics are similar to those of rare, transient, radio-loud magnetars. Using several deep non-detections from the literature and two new detections, we show that this pulsar is also transient in the radio. Both the flat spectrum and large amplitude variability are inconsistent with the light curves and spectral indices of three radio pulsars with high magnetic field strengths. We further use frequent, deep archival imaging observations of the GC in the past 15 yr to rule out a possible X-ray outburst with a luminosity exceeding the rotational spin-down rate. This source, either a transient magnetar without any detected X-ray counterpart or a young, strongly magnetized radio pulsar producing magnetar-like radio emission, further blurs the line between the two categories. We discuss the implications of this object for the radio emission mechanism in magnetars and for star and compact object formation in the GC.

TIMING OBSERVATIONS OF PSR J1023+0038 DURING A LOW-MASS X-RAY BINARY STATE

Energy Technology Data Exchange (ETDEWEB)

Jaodand, Amruta; Archibald, Anne M.; Hessels, Jason W. T.; Bassa, Cees; Deller, Adam T. [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); D’Angelo, Caroline R.; Patruno, Alessandro [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

2016-10-20

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{sup −15} Hz s{sup −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.

Low-frequency polarimetry of the millisecond pulsar PSR1937+214

Energy Technology Data Exchange (ETDEWEB)

Stinebring, D R [National Radio Astronomy Observatory, Charlottesville, VA (USA); Cordes, J M [Cornell Univ., Ithaca, NY (USA). Dept. of Astronomy; Cornell Univ., Ithaca, NY (USA). National Astronomy and Ionospheric Center)

1983-11-24

Polarization observations are reported at 431 MHz that have 4 ..mu..s time resolution and are free from the effects of interstellar dispersion. The interpulse polarization decreases towards lower frequencies, opposite in trend to the polarization of the main pulse and of most other pulsars. The position angles at the center of the main pulse and interpulse are approximately equal and the position angle gradients have the same sign, supporting a model in which the main pulse and interpulse are emitted above opposite magnetic poles.

Modelling gamma-ray light curves of phase-aligned millisecond pulsars

Science.gov (United States)

Chang, Shan; Zhang, Li; Li, Xiang; Jiang, Zejun

2018-04-01

Three gamma-ray millisecond pulsars (MSPs), PSR J1939+2134, PSR J1959+2048, and PSR J0034-0534, have been confirmed to have a common feature of phase-aligned in radio and gamma-ray bands. With a geometric (two-pole caustic) model and a physical outer gap model (revised 3D outer gap model) in a three dimensional (3D) retarded magnetic dipole with a perturbation magnetic field, the observed features of these MSPs are studied. In order to obtained the best-fitting model parameters, the Markov chain Monte Carlo technique is used and reasonable GeV band light curves for three MSPs are given. Our calculations indicate that MSPs emit high energy photons with smaller inclination angles (α ≈ 10°-50°), larger view angles (ζ ≈ 65°-100°), and smaller perturbation factor (ɛ ≈ -0.15-0.1). Note that the factor ɛ, describing the strength of the perturbed magnetic field, is all less than zero in these two models, so the magnetic field caused by current-induced play a leading role in the pulsed location of MSPs.

A RADIO-LOUD MAGNETAR IN X-RAY QUIESCENCE

International Nuclear Information System (INIS)

Levin, Lina; Bailes, Matthew; Bhat, N. D. Ramesh; Burke-Spolaor, Sarah; Van Straten, Willem; Bates, Samuel; Kramer, Michael; Stappers, Ben; Burgay, Marta; D'Amico, Nichi; Milia, Sabrina; Possenti, Andrea; Johnston, Simon; Keith, Michael; Rea, Nanda

2010-01-01

As part of a survey for radio pulsars with the Parkes 64 m telescope, we have discovered PSR J1622-4950, a pulsar with a 4.3 s rotation period. Follow-up observations show that the pulsar has the highest inferred surface magnetic field of the known radio pulsars (B ∼3 x 10 14 G), and it exhibits significant timing noise and appears to have an inverted spectrum. Unlike the vast majority of the known pulsar population, PSR J1622-4950 appears to switch off for many hundreds of days and even in its on-state exhibits extreme variability in its flux density. Furthermore, the integrated pulse profile changes shape with epoch. All of these properties are remarkably similar to the only two magnetars previously known to emit radio pulsations. The position of PSR J1622-4950 is coincident with an X-ray source that, unlike the other radio pulsating magnetars, was found to be in quiescence. We conclude that our newly discovered pulsar is a magnetar-the first to be discovered via its radio emission.

STRUCTURES OF THE VELA PULSAR AND THE GLITCH CRISIS FROM THE BRUECKNER THEORY

Energy Technology Data Exchange (ETDEWEB)

Li, A. [Department of Astronomy, Xiamen University, Xiamen, Fujian 361005 (China); Dong, J. M. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, J. B. [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011 (China); Xu, R. X., E-mail: liang@xmu.edu.cn [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China)

2016-03-15

Detailed structures of the Vela pulsar (PSR B0833-45, with a period of 89.33 ms) are predicted by adopting a recently constructed unified treatment of all parts of neutron stars: the outer crust, the inner crust, and the core based on modern microscopic Brueckner–Hartree–Fock calculations. Taking a pulsar mass in the range from 1.0 to 2.0 M{sub ⊙}, we calculate the central density, the core/crust radii, the core/crustal mass, the core/crustal thickness, the moment of inertia, and the crustal moment of inertia. Among them, the crustal moment of inertia could be effectively constrained from the accumulated glitch observations, which has been a great debate recently, known as the “glitch crisis.” Namely, superfluid neutrons contained in the inner crust, which are regarded as the origin of the glitch in the standard two-component model, could be largely entrained in the nuclei lattices, and then there may not be enough superfluid neutrons (∼4/5 less than the previous value) to trigger the large glitches (Δν/ν{sub 0} ∼ 10{sup −6}) in the Vela pulsar. By confronting the glitch observations with the theoretical calculations for the crustal moment of inertia, we find that despite some recent opposition to the crisis argument, the glitch crisis is still present, which means that besides the crustal superfluid neutrons, core neutrons might be necessary for explaining the large glitches of the Vela pulsar.

Models for the formation of binary and millisecond radio pulsars

International Nuclear Information System (INIS)

van den Heuvel, E.P.J.

1984-01-01

The peculiar combination of a relatively short pulse period and a relatively weak surface dipole magnetic field strength of binary radio pulsars finds a consistent explanation in terms of: (i) decay of the surface dipole component of neutron star magnetic fields on a timescale of (2-5).10 6 yrs, in combination with: (ii) spin up of the rotation of the neutron star during a subsequent mass-transfer phase. The two observed classes of binary radio pulsars (very close and very wide systems, respectively) are expected to have been formed by the later evolution of binaries consisting of a neutron star and a normal companion star, in which the companion was (considerably) more massive than the neutron star, or less massive than the neutron star, respectively. In the first case the companion of the neutron star in the final system will be a fairly massive white dwarf, in a circular orbit, or a neutron star in an eccentric orbit. In the second case the final companion to the neutron star will be a low-mass (approx. 0.3 Msub solar) helium white dwarf in a wide and nearly circular orbit. In systems of the second type the neutron star was most probably formed by the accretion-induced collapse of a white dwarf. This explains why PSR 1953+29 has a millisecond rotation period and why PSR 0820+02 has not. Binary coalescence models for the formation of the 1.5 millisecond pulsar appear to be viable. The companion to the neutron star may have been a low-mass red dwarf, a neutron star, or a massive (> 0.7 Msub solar) white dwarf. In the red-dwarf case the progenitor system probably was a CV binary in which the white dwarf collapsed by accretion. 66 references, 6 figures, 1 table

Modeling the emission of the galactic very high energy γ-ray sources G 1.9+0.3, G 330.2+1.0, HESS J1303-631 and PSR B1259-63/LS 2883 observed with H.E.S.S

International Nuclear Information System (INIS)

Sushch, Iurii

2012-01-01

Recently, imaging atmospheric Cherenkov telescopes (IACTs) have discovered numerous new sources representing various source classes in the very high energy (VHE; E>100 GeV) sky. This work presents studies of representatives of three types of Galactic VHE emitters: the Supernova remnants (SNRs) G1.9+0.3 and G330.2+1.0, the pulsar wind nebula (PWN) HESS J1303.631 and the binary system PSR B1259.63/LS 2883. The analysis of the H.E.S.S. data and the broadband emission modeling are presented. G1.9+0.3 and G330.2+1.0 are synchrotron-dominated SNRs whose non-thermal X-ray emission implies that intensive particle acceleration occurs at their shock fronts. This makes them promising candidates for the detection at VHEs. They were observed by the High Energy Stereoscopic System (H.E.S.S.) yielding no signs of significant VHE γ-ray emission from either SNR. The 99% confidence level upper limits on the TeV flux were determined. For an assumed spectral index of 2.5 the obtained upper limits are F G1.9 (>260 GeV) -13 cm -2 s -1 for G1.9+0.3 and F G330 (>380 GeV) -12 cm -2 s -1 for G330.2+1.0. Upper limits on the VHE emission provide constraints on the interior magnetic field in the context of a leptonic scenario and on the interstellar medium (ISM) density and cosmic-ray (CR) efficiency in a hadronic scenario. Lower limits on the interior magnetic fields were estimated at 15 μG for G1.9+0.3 and 14 μG for G330.2+1.0. In the case of the hadronic scenario, the H.E.S.S. upper limits are two orders of magnitude greater than the flux prediction. Obtained upper limits on the ISM densities are compatible with other estimates of the densities (from the thermal X-ray emission for G330.2+1.0 and from the expansion rate for G1.9+0.3). The CR efficiency cannot be constrained with the current H.E.S.S. upper limits. HESS J1303-631 is an initially unidentified H.E.S.S. source which was recently identified as a PWN associated with the pulsar PSR J1301-6305. The broadband emission of the source

Radio Detection of the Fermi-LAT Blind Search Millisecond Pulsar J1311-3430

Science.gov (United States)

Ray, P. S.; Ransom, S. M.; Cheung, C. C.; Giroletti, M.; Cognard, I.; Camilo, F.; Bhattacharyya, B.; Roy, J.; Romani, R. W.; Ferrara, E. C.;

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.

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.;

Transitional millisecond pulsars in the low-level accretion state

Science.gov (United States)

Jaodard, Amruta D.; Hessels, Jason W. T.; Archibald, Anne; Bogdanov, Slavko; Deller, Adam; Hernandez Santisteban, Juan; Patruno, Alessandro; D'Angelo, Caroline; Bassa, Cees; Amruta Jaodand

2018-01-01

In the canonical pulsar recycling scenario, a slowly spinning neutron star can be rejuvenated to rapid spin rates by the transfer of angular momentum and mass from a binary companion star. Over the last decade, the discovery of three transitional millisecond pulsars (tMSPs) has allowed us to study recycling in detail. These systems transition between accretion-powered (X-ray) and rotation-powered (radio) pulsar states within just a few days, raising questions such as: what triggers the state transition, when does the recycling process truly end, and what will the radio pulsar’s final spin rate be? Systematic multi-wavelength campaigns over the last decade have provided critical insights: multi-year-long, low-level accretion states showing coherent X-ray pulsations; extremely stable, bi-modal X-ray light curves; outflows probed by radio continuum emission; a surprising gamma-ray brightening during accretion, etc. In my thesis I am trying to bring these clues together to understand the low-level accretion process that recycles a pulsar. For example, recently we timed PSR J1023+0038 in the accretion state and found it to be spinning down ~26% faster compared to the non-accreting radio pulsar state. We are currently conducting simultaneous multi-wavelength campaigns (XMM, HST, Kepler and VLA) to understand the global variability of the accretion flow, as well as high-energy Fermi-LAT observations to probe the gamma-ray emission mechanism. I will highlight these recent developments, while also presenting a broad overview of tMSPs as exciting new laboratories to test low-level accretion onto magnetized neutron stars.

Pulsar discoveries by volunteer distributed computing and the strongest continuous gravitational wave signal

Science.gov (United States)

Knispel, Benjamin

2011-07-01

Neutron stars are the endpoints of stellar evolution and one of the most compact forms of matter in the universe. They can be observed as radio pulsars and are promising sources for the emission of continuous gravitational waves. Discovering new radio pulsars in tight binary orbits offers the opportunity to conduct very high precision tests of General Relativity and to further our understanding of neutron star structure and matter at super-nuclear densities. The direct detection of gravitational waves would validate Einstein's theory of Relativity and open a new window to the universe by offering a novel astronomical tool. This thesis addresses both of these scientific fields: the first fully coherent search for radio pulsars in tight, circular orbits has been planned, set up and conducted in the course of this thesis. Two unusual radio pulsars, one of them in a binary system, have been discovered. The other half of this thesis is concerned with the simulation of the Galactic neutron star population to predict their emission of continuous gravitational waves. First realistic statistical upper limits on the strongest continuous gravitational-wave signal and detection predictions for realistic all-sky blind searches have been obtained. The data from a large-scale pulsar survey with the 305-m Arecibo radio telescope were searched for signals from radio pulsars in binary orbits. The massive amount of computational work was done on hundreds of thousands of computers volunteered by members of the general public through the distributed computing project Einstein@Home. The newly developed analysis pipeline searched for pulsar spin frequencies below 250 Hz and for orbital periods as short as 11 min. The structure of the search pipeline consisting of data preparation, data analysis, result post-processing, and set-up of the pipeline components is presented in detail. The first radio pulsar, discovered with this search, PSR J2007+2722, is an isolated radio pulsar, likely from

Phase Evolution of the Crab Pulsar between Radio and X-Ray

Energy Technology Data Exchange (ETDEWEB)

Yan, L. L.; Ge, M. Y.; Zheng, S. J.; Lu, F. J.; Tuo, Y. L.; Zhang, S. N.; Lu, Y. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Yuan, J. P.; Tong, H. [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011 (China); Han, J. L. [National Astronomical Observatory, Chinese Academy of Sciences, Jia 20 Datun Road, Beijing 100012 (China); Du, Y. J., E-mail: yanlinli@ihep.ac.cn [Qian Xuesen Laboratory of Space Technology, No. 104, Youyi Road, Haidian District, Beijing 100094 (China)

2017-08-20

We study the X-ray phases of the Crab pulsar utilizing the 11-year observations from the Rossi X-ray Timing Explorer , 6-year radio observations from Nanshan Telescope, and the ephemeris from Jodrell Bank Observatory. It is found that the X-ray phases in different energy bands and the radio phases from the Nanshan Telescope show similar behaviors, including long-time evolution and short-time variations. Such strong correlations between the X-ray and radio phases imply that the radio and X-ray timing noises are both generated from the pulsar spin that cannot be well described by the the monthly ephemeris from the Jodrell Bank observatory. When using the Nanshan phases as references to study the X-ray timing noise, it has a significantly smaller variation amplitude and shows no long-time evolution, with a change rate of (−1.1 ± 1.1) × 10{sup −7} periods per day. These results show that the distance of the X-ray and radio emission regions on the Crab pulsar has no detectable secular change, and it is unlikely that the timing noises resulted from any unique physical processes in the radio or X-ray emitting regions. The similar behaviors of the X-ray and radio timing noises also imply that the variation of the interstellar medium is not the origin of the Crab pulsar’s timing noises, which is consistent with the results obtained from the multi-frequency radio observations of PSR B1540−06.

X-ray measurement of the spin-down of CalverA: A radio- and gamma-ray-quiet pulsar

Energy Technology Data Exchange (ETDEWEB)

Halpern, J. P.; Bogdanov, S.; Gotthelf, E. V., E-mail: jules@astro.columbia.edu [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027-6601 (United States)

2013-12-01

We measure spin-down of the 59 ms X-ray pulsar Calvera by comparing the XMM-Newton discovery data from 2009 with new Chandra timing observations taken in 2013. Its period derivative is P-dot =(3.19± 0.08)×10{sup −15}, which corresponds to spin-down luminosity E-dot =6.1×10{sup 35} erg s{sup –1}, characteristic age τ{sub c}≡P/2 P-dot =2.9×10{sup 5} yr, and surface dipole magnetic field strength B{sub s} = 4.4 × 10{sup 11} G. These values rule out a mildly recycled pulsar, but Calvera could be an orphaned central compact object (anti-magnetar), with a magnetic field that was initially buried by supernova debris and is now reemerging and approaching normal strength. We also performed unsuccessful searches for high-energy γ-rays from Calvera in both imaging and timing of >100 MeV Fermi photons. Even though the distance to Calvera is uncertain by an order of magnitude, an upper limit of d < 2 kpc inferred from X-ray spectra implies a γ-ray luminosity limit of <3.3 × 10{sup 32} erg s{sup –1}, which is less than that of any pulsar of comparable E-dot . Calvera shares some properties with PSR J1740+1000, a young radio pulsar that we show by virtue of its lack of proper motion was born outside of the Galactic disk. As an energetic, high-Galactic-latitude pulsar, Calvera is unique in being undetected in both radio and γ-rays to faint limits, which should place interesting constraints on models for particle acceleration and beam patterns in pulsar magnetospheres.

Binary pulsar PSR 1718-19 contains a stripped main-sequence turn-off star

International Nuclear Information System (INIS)

Zwitter, T.

1993-05-01

Lyne et al. (1993) have recently announced the discovery of a 1-second globular cluster pulsar, 1718-19, in a 6.2-hour binary system which is embedded in a cloud of material originating from the companion star. However the incident flux of the pulsar's radiation on the companion is too low to ablate it and a main sequence companion is too small to fill its Roche lobe. Here I argue that the companion is a stripped turn-off star of 0.2-0.4 solar masses (M sun ) and with approx. 0.1M sun helium core. It has approx. 1.8-times larger radius than a main sequence star of equal mass. Its position in the Hertzsprung-Russell diagram overlaps that of a ∼ 0.65M sun main-sequence star. The evolutionary state of the companion and the highly magnetized slowly rotating neutron star place the system on the verge of the low mass X-ray binary phase. (author). 19 refs, 2 figs

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.

Scintillation-based Search for Off-pulse Radio Emission from Pulsars

Science.gov (United States)

Ravi, Kumar; Deshpande, Avinash A.

2018-05-01

We propose a new method to detect off-pulse (unpulsed and/or continuous) emission from pulsars using the intensity modulations associated with interstellar scintillation. Our technique involves obtaining the dynamic spectra, separately for on-pulse window and off-pulse region, with time and frequency resolutions to properly sample the intensity variations due to diffractive scintillation and then estimating their mutual correlation as a measure of off-pulse emission, if any. We describe and illustrate the essential details of this technique with the help of simulations, as well as real data. We also discuss the advantages of this method over earlier approaches to detect off-pulse emission. In particular, we point out how certain nonidealities inherent to measurement setups could potentially affect estimations in earlier approaches and argue that the present technique is immune to such nonidealities. We verify both of the above situations with relevant simulations. We apply this method to the observation of PSR B0329+54 at frequencies of 730 and 810 MHz made with the Green Bank Telescope and present upper limits for the off-pulse intensity at the two frequencies. We expect this technique to pave the way for extensive investigations of off-pulse emission with the help of existing dynamic spectral data on pulsars and, of course, with more sensitive long-duration data from new observations.

PALFA Discovery of a Highly Relativistic Double Neutron Star Binary

Science.gov (United States)

Stovall, K.; Freire, P. C. C.; Chatterjee, S.; Demorest, P. B.; Lorimer, D. R.; McLaughlin, M. A.; Pol, N.; van Leeuwen, J.; Wharton, R. S.; Allen, B.; Boyce, M.; Brazier, A.; Caballero, K.; Camilo, F.; Camuccio, R.; Cordes, J. M.; Crawford, F.; Deneva, J. S.; Ferdman, R. D.; Hessels, J. W. T.; Jenet, F. A.; Kaspi, V. M.; Knispel, B.; Lazarus, P.; Lynch, R.; Parent, E.; Patel, C.; Pleunis, Z.; Ransom, S. M.; Scholz, P.; Seymour, A.; Siemens, X.; Stairs, I. H.; Swiggum, J.; Zhu, W. W.

2018-02-01

We report the discovery and initial follow-up of a double neutron star (DNS) system, PSR J1946+2052, with the Arecibo L-Band Feed Array pulsar (PALFA) survey. PSR J1946+2052 is a 17 ms pulsar in a 1.88 hr, eccentric (e = 0.06) orbit with a ≳1.2 M ⊙ companion. We have used the Jansky Very Large Array to localize PSR J1946+2052 to a precision of 0.″09 using a new phase binning mode. We have searched multiwavelength catalogs for coincident sources but did not find any counterparts. The improved position enabled a measurement of the spin period derivative of the pulsar (\\dot{P}=9+/- 2× {10}-19); the small inferred magnetic field strength at the surface (B S = 4 × 109 G) indicates that this pulsar has been recycled. This and the orbital eccentricity lead to the conclusion that PSR J1946+2052 is in a DNS system. Among all known radio pulsars in DNS systems, PSR J1946+2052 has the shortest orbital period and the shortest estimated merger timescale, 46 Myr; at that time it will display the largest spin effects on gravitational-wave waveforms of any such system discovered to date. We have measured the advance of periastron passage for this system, \\dot{ω }=25.6+/- 0.3 \\deg {yr}}-1, implying a total system mass of only 2.50 ± 0.04 M ⊙, so it is among the lowest-mass DNS systems. This total mass measurement combined with the minimum companion mass constrains the pulsar mass to ≲1.3 M ⊙.

Modeling the emission of the galactic very high energy {gamma}-ray sources G 1.9+0.3, G 330.2+1.0, HESS J1303-631 and PSR B1259-63/LS 2883 observed with H.E.S.S

Energy Technology Data Exchange (ETDEWEB)

Sushch, Iurii

2012-10-19

Recently, imaging atmospheric Cherenkov telescopes (IACTs) have discovered numerous new sources representing various source classes in the very high energy (VHE; E>100 GeV) sky. This work presents studies of representatives of three types of Galactic VHE emitters: the Supernova remnants (SNRs) G1.9+0.3 and G330.2+1.0, the pulsar wind nebula (PWN) HESS J1303.631 and the binary system PSR B1259.63/LS 2883. The analysis of the H.E.S.S. data and the broadband emission modeling are presented. G1.9+0.3 and G330.2+1.0 are synchrotron-dominated SNRs whose non-thermal X-ray emission implies that intensive particle acceleration occurs at their shock fronts. This makes them promising candidates for the detection at VHEs. They were observed by the High Energy Stereoscopic System (H.E.S.S.) yielding no signs of significant VHE {gamma}-ray emission from either SNR. The 99% confidence level upper limits on the TeV flux were determined. For an assumed spectral index of 2.5 the obtained upper limits are F{sub G1.9}(>260 GeV)<4.6 x 10{sup -13} cm{sup -2}s{sup -1} for G1.9+0.3 and F{sub G330}(>380 GeV)<1.6 x 10{sup -12} cm{sup -2}s{sup -1} for G330.2+1.0. Upper limits on the VHE emission provide constraints on the interior magnetic field in the context of a leptonic scenario and on the interstellar medium (ISM) density and cosmic-ray (CR) efficiency in a hadronic scenario. Lower limits on the interior magnetic fields were estimated at 15 {mu}G for G1.9+0.3 and 14 {mu}G for G330.2+1.0. In the case of the hadronic scenario, the H.E.S.S. upper limits are two orders of magnitude greater than the flux prediction. Obtained upper limits on the ISM densities are compatible with other estimates of the densities (from the thermal X-ray emission for G330.2+1.0 and from the expansion rate for G1.9+0.3). The CR efficiency cannot be constrained with the current H.E.S.S. upper limits. HESS J1303-631 is an initially unidentified H.E.S.S. source which was recently identified as a PWN associated with

EFFECTS OF INTERMITTENT EMISSION: NOISE INVENTORY FOR THE SCINTILLATING PULSAR B0834+06

International Nuclear Information System (INIS)

Gwinn, C. R.; Johnson, M. D.; Smirnova, T. V.; Stinebring, D. R.

2011-01-01

We compare signal and noise for observations of the scintillating pulsar B0834+06, using very long baseline interferometry and a single-dish spectrometer. Comparisons between instruments and with models suggest that amplitude variations of the pulsar strongly affect the amount and distribution of self-noise. We show that noise follows a quadratic polynomial with flux density, in spectral observations. Constant coefficients, indicative of background noise, agree well with expectation; whereas second-order coefficients, indicative of self-noise, are ∼3 times values expected for a pulsar with constant on-pulse flux density. We show that variations in flux density during the 10 s integration accounts for the discrepancy. In the secondary spectrum, ∼97% of spectral power lies within the pulsar's typical scintillation bandwidth and timescale; an extended scintillation arc contains ∼3%. For a pulsar with constant on-pulse flux density, noise in the dynamic spectrum will appear as a uniformly distributed background in the secondary spectrum. We find that this uniform noise background contains 95% of noise in the dynamic spectrum for interferometric observations; but only 35% of noise in the dynamic spectrum for single-dish observations. Receiver and sky dominate noise for our interferometric observations, whereas self-noise dominates for single-dish. We suggest that intermittent emission by the pulsar, on timescales <300 μs, concentrates self-noise near the origin in the secondary spectrum, by correlating noise over the dynamic spectrum. We suggest that intermittency sets fundamental limits on pulsar astrometry or timing. Accounting of noise may provide means for detection of intermittent sources, when effects of propagation are unknown or impractical to invert.

Serendipitous discovery of an infrared bow shock near PSR J1549–4848 with Spitzer

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhongxiang [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Kaplan, David L. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Slane, Patrick [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Morrell, Nidia [Las Campanas Observatory, Observatories of the Carnegie Institution of Washington, La Serena (Chile); Kaspi, Victoria M. [Department of Physics, McGill University, 3600 University Street, Montreal, QC H3A 2T8 (Canada)

2013-06-01

We report on the discovery of an infrared cometary nebula around PSR J1549–4848 in our Spitzer survey of a few middle-aged radio pulsars. Following the discovery, multi-wavelength imaging and spectroscopic observations of the nebula were carried out. We detected the nebula in Spitzer Infrared Array Camera 8.0, Multiband Imaging Photometer for Spitzer 24 and 70 μm imaging, and in Spitzer IRS 7.5-14.4 μm spectroscopic observations, and also in the Wide-field Infrared Survey Explorer all-sky survey at 12 and 22 μm. These data were analyzed in detail, and we find that the nebula can be described with a standard bow shock shape, and that its spectrum contains polycyclic aromatic hydrocarbon and H{sub 2} emission features. However, it is not certain which object drives the nebula. We analyze the field stars and conclude that none of them can be the associated object because stars with a strong wind or mass ejection that usually produce bow shocks are much brighter than the field stars. The pulsar is approximately 15'' away from the region in which the associated object is expected to be located. In order to resolve the discrepancy, we suggest that a highly collimated wind could be emitted from the pulsar and produce the bow shock. X-ray imaging to detect the interaction of the wind with the ambient medium- and high-spatial resolution radio imaging to determine the proper motion of the pulsar should be carried out, which will help verify the association of the pulsar with the bow shock nebula.

Millisecond pulsars: Timekeepers of the cosmos

Science.gov (United States)

Kaspi, Victoria M.

1995-01-01

A brief discussion on the characteristics of pulsars is given followed by a review of millisecond pulsar discoveries including the very first, PRS B1937+21, discovered in 1982. Methods of timing millisecond pulsars and the accuracy of millisecond pulsars as clocks are discussed. Possible reasons for the pulse residuals, or differences between the observed and predicted pulse arrival times for millisecond pulsars, are given.

Algorithms for searching Fast radio bursts and pulsars in tight binary systems.

Science.gov (United States)

Zackay, Barak

2017-01-01

Fast radio bursts (FRB's) are an exciting, recently discovered, astrophysical transients which their origins are unknown.Currently, these bursts are believed to be coming from cosmological distances, allowing us to probe the electron content on cosmological length scales. Even though their precise localization is crucial for the determination of their origin, radio interferometers were not extensively employed in searching for them due to computational limitations.I will briefly present the Fast Dispersion Measure Transform (FDMT) algorithm,that allows to reduce the operation count in blind incoherent dedispersion by 2-3 orders of magnitude.In addition, FDMT enables to probe the unexplored domain of sub-microsecond astrophysical pulses.Pulsars in tight binary systems are among the most important astrophysical objects as they provide us our best tests of general relativity in the strong field regime.I will provide a preview to a novel algorithm that enables the detection of pulsars in short binary systems using observation times longer than an orbital period.Current pulsar search programs limit their searches for integration times shorter than a few percents of the orbital period.Until now, searching for pulsars in binary systems using observation times longer than an orbital period was considered impossible as one has to blindly enumerate all options for the Keplerian parameters, the pulsar rotation period, and the unknown DM.Using the current state of the art pulsar search techniques and all computers on the earth, such an enumeration would take longer than a Hubble time. I will demonstrate that using the new algorithm, it is possible to conduct such an enumeration on a laptop using real data of the double pulsar PSR J0737-3039.Among the other applications of this algorithm are:1) Searching for all pulsars on all sky positions in gamma ray observations of the Fermi LAT satellite.2) Blind searching for continuous gravitational wave sources emitted by pulsars with

Discovery of a remarkable subpulse drift pattern in PSR B0818-41

Science.gov (United States)

Bhattacharyya, B.; Gupta, Y.; Gil, J.; Sendyk, M.

2007-05-01

We report the discovery of a remarkable subpulse drift pattern in the relatively less-studied wide profile pulsar B0818-41 using high-sensitivity Giant Metrewave Radio Telescope (GMRT) observations. We find simultaneous occurrences of three drift regions with two different drift rates: an inner region with steeper apparent drift rate flanked on each side by a region of slower apparent drift rate. Furthermore, these closely spaced drift bands always maintain a constant phase relationship. Though these drift regions have significantly different values for the measured P2, the measured P3 value is the same and equal to 18.3P1. We interpret the unique drift pattern of this pulsar as being created by the intersection of our line of sight (LOS) with two conal rings on the polar cap of a fairly aligned rotator (inclination angle α ~ 11°), with an `inner' LOS geometry (impact angle ). We argue that both rings have the same values for the carousel rotation periodicity P4 and the number of sparks Nsp. We find that Nsp is 19-21 and show that it is very likely that P4 is the same as the measured P3, making it a truly unique pulsar. We present results from simulations of the radiation pattern using the inferred parameters, which support our interpretations and reproduce the average profile as well as the observed features in the drift pattern quite well.

Multifrequency Behaviour of the Gamma-Ray Binary System PSR B1259-63: Modelling the FERMI Flare

Directory of Open Access Journals (Sweden)

Brian van Soelen

2014-12-01

Full Text Available This paper presents a brief overview of the multifrequency properties of the gamma-ray binary system PSR B1259-63 from radio to very high energy gamma-rays. A summary is also presented of the various models put forward to explain the Fermi "flare" detected in 2011. Initial results are presented of a new turbulence driven model to explain the GeV observations.

On the origin of the system PSR B1757-24/SNR G5.4-1.2

OpenAIRE

Gvaramadze, V. V.

2003-01-01

A scenario for the origin of the system PSR B1757-24/supernova remnant (SNR) G5.4-1.2 is proposed. It is suggested that both objects are the remnants of a supernova (SN) that exploded within a pre-existing bubble blown-up by a runaway massive star (the SN progenitor) during the final (Wolf-Rayet) phase of its evolution. This suggestion implies that (a) the SN blast centre was significantly offset from the geometric centre of the wind-blown bubble (i.e. from the centre of the future SNR), (b) ...

PSR B0329+54: substructure in the scatter-broadened image discovered with RadioAstron on baselines up to 330 000 km

Science.gov (United States)

Popov, Mikhail V.; Bartel, Norbert; Gwinn, Carl R.; Johnson, Michael D.; Andrianov, Andrey; Fadeev, Evgeny; Joshi, Bhal Chandra; Kardashev, Nikolay; Karuppusamy, Ramesh; Kovalev, Yuri Y.; Kramer, Michael; Rudnitskiy, Alexey; Shishov, Vladimir; Smirnova, Tatiana; Soglasnov, Vladimir A.; Zensus, J. Anton

2017-02-01

We have resolved the scatter-broadened image of PSR B0329+54 and detected a substructure within it. These results are not influenced by any extended structure of a source but instead are directly attributed to the interstellar medium. We obtained these results at 324 MHz with the ground-space interferometer RadioAstron, which included the Space Radio Telescope, ground-based Westerbork Synthesis Radio Telescope and 64-m Kalyazin Radio Telescope on baseline projections up to 330 000 km in 2013 November 22 and 2014 January 1 to 2. At short 15 000 to 35 000 km ground-space baseline projections, the visibility amplitude decreases with baseline length, providing a direct measurement of the size of the scattering disc of 4.8 ± 0.8 mas. At longer baselines, no visibility detections from the scattering disc would be expected. However, significant detections were obtained with visibility amplitudes of 3 to 5 per cent of the maximum scattered around a mean and approximately constant up to 330 000 km. These visibilities reflect a substructure from scattering in the interstellar medium and offer a new probe of ionized interstellar material. The size of the diffraction spot near Earth is 17 000 ± 3 000 km. With the assumption of turbulent irregularities in the plasma of the interstellar medium, we estimate that the effective scattering screen is located 0.6 ± 0.1 of the distance from the Earth towards the pulsar.

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.

A 24 hr global campaign to assess precision timing of the millisecond pulsar J1713+0747

Energy Technology Data Exchange (ETDEWEB)

Dolch, T.; Lam, M. T.; Cordes, J.; Chatterjee, S. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Bassa, C.; Hessels, J. W. T.; Janssen, G.; Kondratiev, V. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Bhattacharyya, B.; Jordan, C.; Keith, M. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Champion, D. J.; Karuppusamy, R.; Kramer, M.; Lazarus, P. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement et de l' Espace, LPC2E UMR 6115 CNRS, F-45071 Orléans Cedex 02, and Station de radioastronomie de Nançay, Observatoire de Paris, CNRS/INSU, F-18330 Nançay (France); Crowter, K. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Demorest, P. B. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22901 (United States); Jenet, F. A. [Center for Advanced Radio Astronomy, University of Texas, Rio Grande Valley, Brownsville, TX 78520 (United States); Jones, G., E-mail: tdolch@astro.cornell.edu [Columbia Astrophysics Laboratory, Columbia University, NY 10027 (United States); and others

2014-10-10

The radio millisecond pulsar J1713+0747 is regarded as one of the highest-precision clocks in the sky and is regularly timed for the purpose of detecting gravitational waves. The International Pulsar Timing Array Collaboration undertook a 24 hr global observation of PSR J1713+0747 in an effort to better quantify sources of timing noise in this pulsar, particularly on intermediate (1-24 hr) timescales. We observed the pulsar continuously over 24 hr with the Arecibo, Effelsberg, GMRT, Green Bank, LOFAR, Lovell, Nançay, Parkes, and WSRT radio telescopes. The combined pulse times-of-arrival presented here provide an estimate of what sources of timing noise, excluding DM variations, would be present as compared to an idealized √N improvement in timing precision, where N is the number of pulses analyzed. In the case of this particular pulsar, we find that intrinsic pulse phase jitter dominates arrival time precision when the signal-to-noise ratio of single pulses exceeds unity, as measured using the eight telescopes that observed at L band/1.4 GHz. We present first results of specific phenomena probed on the unusually long timescale (for a single continuous observing session) of tens of hours, in particular interstellar scintillation, and discuss the degree to which scintillation and profile evolution affect precision timing. This paper presents the data set as a basis for future, deeper studies.

Deep optical observations of the γ-ray pulsar J0357+3205

Science.gov (United States)

Kirichenko, A.; Danilenko, A.; Shibanov, Yu.; Shternin, P.; Zharikov, S.; Zyuzin, D.

2014-04-01

Context. A middle-aged radio-quiet pulsar J0357+3205 was discovered in gamma rays with Fermi and later in X-rays with Chandra and XMM-Newton observatories. It produces an unusual thermally emitting pulsar wind nebula that is observed in X-rays. Aims: Deep optical observations were obtained to search for the pulsar optical counterpart and its nebula using the Gran Telescopio Canarias (GTC). Methods: The direct imaging mode in the Sloan g' band was used. Archival X-ray data were reanalysed and compared with the optical data. Results: No pulsar optical counterpart was detected down to g'≥slant 28.1m. No pulsar nebula was identified in the optical either. We confirm early results that the X-ray spectrum of the pulsar consists of a nonthermal power-law component of the pulsar magnetospheric origin dominating at high energies and a soft thermal component from the neutron star surface. Using magnetised, partially ionised hydrogen atmosphere models in X-ray spectral fits, we found that the thermal component can come from the entire surface of the cooling neutron star with a temperature of 36+8-6 eV, making it one of the coldest among cooling neutron stars known. The surface temperature agrees with the standard neutron star cooling scenario. The optical upper limit does not put any additional constraints on the thermal component, however it does imply a strong spectral break for the nonthermal component between the optical and X-rays as is observed in other middle-aged pulsars. Conclusions: The thermal emission from the entire surface of the neutron star very likely dominates the nonthermal emission in the UV range. Observations of PSR J0357+3205 in this range are promising to put more stringent constraints on its thermal properties. Based on observations made with the Gran Telescopio Canarias (GTC), instaled in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma under Programme GTC3-12BMEX

Pulsed Gamma-Rays From PSR J2021 3651 with the Fermi Large Area Telescope

International Nuclear Information System (INIS)

Abdo, Aous A.; Ackermann, M.; Ajello, Marco; Atwood, William B.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Bastieri, Denis; Battelino, Milan; Baughman, B.M.; Bechtol, K.; Bellazzini, Ronaldo; Berenji, Bijan; Bloom, Elliott D.; Bogaert, G.; Borgland, Anders W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, Thompson H.

2009-01-01

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 -8 cm -2 s -1 . The photon spectrum is well-described by an exponentially cut-off power law of the form dF/dE = kE -# Gamma#e (-E/E c ) where the energy E is expressed in GeV. The photon index is Γ = 1.5 ± 0.1 ± 0.1 and the exponential cut-off is E 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 -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.

Radio emissions from pulsar companions: a refutable explanation for galactic transients and fast radio bursts

Science.gov (United States)

Mottez, F.; Zarka, P.

2014-09-01

Context. The six known highly dispersed fast radio bursts are attributed to extragalactic radio sources that are of unknown origin but extremely energetic. We propose here a new explanation that does not require an extreme release of energy and involves a body (planet, asteroid, white dwarf) orbiting an extragalactic pulsar. Aims: We investigate a theory of radio waves associated with such pulsar-orbiting bodies. We focus our analysis on the waves emitted from the magnetic wake of the body in the pulsar wind. After deriving their properties, we compare them with the observations of various transient radio signals to determine whether they could originate from pulsar-orbiting bodies. Methods: The analysis is based on the theory of Alfvén wings: for a body immersed in a pulsar wind, a system of two stationary Alfvén waves is attached to the body, provided that the wind is highly magnetised. When they are destabilised through plasma instabilities, Alfvén wings can be the locus of strong radio sources that are convected with the pulsar wind. By assuming a cyclotron maser instability operating in the Alfvén wings, we make predictions about the shape, frequencies, and brightness of the resulting radio emissions. Results: Because of the beaming by relativistic aberration, the signal is seen only when the companion is perfectly aligned between its parent pulsar and the observer, as is the case for occultations. For pulsar winds with a high Lorentz factor (≥104), the whole duration of the radio event does not exceed a few seconds, and it is composed of one to four peaks that last a few milliseconds each and are detectable up to distances of several Mpc. The Lorimer burst, the three isolated pulses of PSR J1928+15, and the recently detected fast radio bursts are all compatible with our model. According to it, these transient signals should repeat periodically with the companion's orbital period. Conclusions: The search of pulsar-orbiting bodies could be an exploration

Improving timing sensitivity in the microhertz frequency regime: limits from PSR J1713+0747 on gravitational waves produced by super-massive black-hole binaries

Science.gov (United States)

Perera, B. B. P.; Stappers, B. W.; Babak, S.; Keith, M. J.; Antoniadis, J.; Bassa, C. G.; Caballero, R. N.; Champion, D. J.; Cognard, I.; Desvignes, G.; Graikou, E.; Guillemot, L.; Janssen, G. H.; Karuppusamy, R.; Kramer, M.; Lazarus, P.; Lentati, L.; Liu, K.; Lyne, A. G.; McKee, J. W.; Osłowski, S.; Perrodin, D.; Sanidas, S. A.; Sesana, A.; Shaifullah, G.; Theureau, G.; Verbiest, J. P. W.; Taylor, S. R.

2018-05-01

We search for continuous gravitational waves (CGWs) produced by individual super-massive black-hole binaries (SMBHBs) in circular orbits using high-cadence timing observations of PSR J1713+0747. We observe this millisecond pulsar using the telescopes in the European Pulsar Timing Array (EPTA) with an average cadence of approximately 1.6 days over the period between April 2011 and July 2015, including an approximately daily average between February 2013 and April 2014. The high-cadence observations are used to improve the pulsar timing sensitivity across the GW frequency range of 0.008 - 5 μHz. We use two algorithms in the analysis, including a spectral fitting method and a Bayesian approach. For an independent comparison, we also use a previously published Bayesian algorithm. We find that the Bayesian approaches provide optimal results and the timing observations of the pulsar place a 95 per cent upper limit on the sky-averaged strain amplitude of CGWs to be ≲ 3.5 × 10-13 at a reference frequency of 1 μHz. We also find a 95 per cent upper limit on the sky-averaged strain amplitude of low-frequency CGWs to be ≲ 1.4 × 10-14 at a reference frequency of 20 nHz.

Higher-order relativistic periastron advances and binary pulsars

International Nuclear Information System (INIS)

Damour, T.; Schafer, G.

1988-01-01

The contributions to the periastron advance of a system of two condensed bodies coming from relativistic dynamical effects of order higher than the usual first post-Newtonian (1PN) equations of motion are investigated. The structure of the solution of the orbital second post-Newtonian (2PN) equations of motion is given in a simple parametrized form. The contributions to the secular pariastron advance, and the period, of orbital 2PN effects are then explicitly worked out by using the Hamilton-Jacobi method. The spin-orbit contribution to the secular precession of the orbit in space is rederived in a streamlined way by making full use of Hamiltonian methods. These results are then applied to the theoretical interpretation of the observational data of pulsars in close eccentric binary systems. It is shown that the higher-order relativistic contributions are already of theoretical and astophysical significance for interpreting the high-precision measurement of the secular periastron advance of PSR 1913+16 achived by Taylor and coworkers. The case of extremely fast spinning (millisecond) binary pulsars is also discussed, and shown to offer an easier ground for getting new tests of general relativity, and/or, a direct measurement of the moment of inertia of a neutron star

High-energy gamma-ray emission in compact binaries

International Nuclear Information System (INIS)

Cerutti, Benoit

2010-01-01

Four gamma-ray sources have been associated with binary systems in our Galaxy: the micro-quasar Cygnus X-3 and the gamma-ray binaries LS I +61 degrees 303, LS 5039 and PSR B1259-63. These systems are composed of a massive companion star and a compact object of unknown nature, except in PSR B1259-63 where there is a young pulsar. I propose a comprehensive theoretical model for the high-energy gamma-ray emission and variability in gamma-ray emitting binaries. In this model, the high-energy radiation is produced by inverse Compton scattering of stellar photons on ultra-relativistic electron-positron pairs injected by a young pulsar in gamma-ray binaries and in a relativistic jet in micro-quasars. Considering anisotropic inverse Compton scattering, pair production and pair cascade emission, the TeV gamma-ray emission is well explained in LS 5039. Nevertheless, this model cannot account for the gamma-ray emission in LS I +61 degrees 303 and PSR B1259-63. Other processes should dominate in these complex systems. In Cygnus X-3, the gamma-ray radiation is convincingly reproduced by Doppler-boosted Compton emission of pairs in a relativistic jet. Gamma-ray binaries and micro-quasars provide a novel environment for the study of pulsar winds and relativistic jets at very small spatial scales. (author)

Neutron Star Physics in the SKA Era An Indian Perspective

Indian Academy of Sciences (India)

65

2016-07-04

Jul 4, 2016 ... (a) These are mainly the classical radio pulsars (PSR - P ∼ 1 s, B ∼ 10. 11 ..... the 300−500 MHz bandwidth, a sampling time of about 80 µs and a dwell time of 300 s, the entire northern sky can be ..... to a misalignment of the rotation and the magnetic axes of the pulsar (Radhakrishnan & Cooke 1969).

Pulsars

CERN Document Server

Smith, Francis Graham

1977-01-01

The discovery of the pulsars ; techniques for search and for observation ; the identification with rotating neutron stars ; the X-ray pulsars ; the internal structure of neutron stars ; the magnetosphere of neutron stars ; pulse timing ; properties of the integrated radio pulses ; individual radio pulses ; the Crab nebula ; the Crab pulsar ; the interstellar medium as an indicator of pulsar distances ; the interstellar magnetic field ; interstellar scintillation ; radiation processes ; the emission mechanism I : analysis of observed particles ; the emission mechanism II : geometrical considerations ; the emission mechanism : discussion ; supernovae : the origin of the pulsars ; the distribution and the ages of pulsars ; high energies and condensed stars.

Toward an Empirical Theory of Pulsar Emission. XII. Exploring the Physical Conditions in Millisecond Pulsar Emission Regions

International Nuclear Information System (INIS)

Rankin, Joanna M.; Mitra, Dipanjan; Archibald, Anne; Hessels, Jason; Leeuwen, Joeri van; Ransom, Scott; Stairs, Ingrid; Straten, Willem van; Weisberg, Joel M.

2017-01-01

The five-component profile of the 2.7 ms pulsar J0337+1715 appears to exhibit the best example to date of a core/double-cone emission-beam structure in a millisecond pulsar (MSP). Moreover, three other MSPs, the binary pulsars B1913+16, B1953+29, and J1022+1001, seem to exhibit core/single-cone profiles. These configurations are remarkable and important because it has not been clear whether MSPs and slow pulsars exhibit similar emission-beam configurations, given that they have considerably smaller magnetospheric sizes and magnetic field strengths. MSPs thus provide an extreme context for studying pulsar radio emission. Particle currents along the magnetic polar flux tube connect processes just above the polar cap through the radio-emission region to the light-cylinder and the external environment. In slow pulsars, radio-emission heights are typically about 500 km around where the magnetic field is nearly dipolar, and estimates of the physical conditions there point to radiation below the plasma frequency and emission from charged solitons by the curvature process. We are able to estimate emission heights for the four MSPs and carry out a similar estimation of physical conditions in their much lower emission regions. We find strong evidence that MSPs also radiate by curvature emission from charged solitons.

Toward an Empirical Theory of Pulsar Emission. XII. Exploring the Physical Conditions in Millisecond Pulsar Emission Regions

Energy Technology Data Exchange (ETDEWEB)

Rankin, Joanna M.; Mitra, Dipanjan [Physics Department, University of Vermont, Burlington, VT 05405 (United States); Archibald, Anne; Hessels, Jason; Leeuwen, Joeri van [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Ransom, Scott [National Radio Astronomy Observatory, Charlottesville, VA 29201 (United States); Stairs, Ingrid [Physics Department, University of British Columbia, V6T 1Z4, BC (Canada); Straten, Willem van [Institute for Radio Astronomy and Space Research, Auckland University of Technology, Auckland 1142 (New Zealand); Weisberg, Joel M., E-mail: Joanna.Rankin@uvm.edu [Physics and Astronomy Department, Carleton College, Northfield, MN 55057 (United States)

2017-08-10

The five-component profile of the 2.7 ms pulsar J0337+1715 appears to exhibit the best example to date of a core/double-cone emission-beam structure in a millisecond pulsar (MSP). Moreover, three other MSPs, the binary pulsars B1913+16, B1953+29, and J1022+1001, seem to exhibit core/single-cone profiles. These configurations are remarkable and important because it has not been clear whether MSPs and slow pulsars exhibit similar emission-beam configurations, given that they have considerably smaller magnetospheric sizes and magnetic field strengths. MSPs thus provide an extreme context for studying pulsar radio emission. Particle currents along the magnetic polar flux tube connect processes just above the polar cap through the radio-emission region to the light-cylinder and the external environment. In slow pulsars, radio-emission heights are typically about 500 km around where the magnetic field is nearly dipolar, and estimates of the physical conditions there point to radiation below the plasma frequency and emission from charged solitons by the curvature process. We are able to estimate emission heights for the four MSPs and carry out a similar estimation of physical conditions in their much lower emission regions. We find strong evidence that MSPs also radiate by curvature emission from charged solitons.

Pulsar Wind Nebulae Created by Fast-Moving Pulsars

OpenAIRE

Kargaltsev, Oleg; Pavlov, George G.; Klingler, Noel; Rangelov, Blagoy

2017-01-01

We review multiwavelength properties of pulsar wind nebulae (PWNe) created by supersonically moving pulsars and the effects of pulsar motion on the PWN morphologies and the ambient medium. Supersonic pulsar wind nebulae (SPWNe) are characterized by bow-shaped shocks around the pulsar and/or cometary tails filled with the shocked pulsar wind. In the past several years significant advances in SPWN studies have been made in deep observations with the Chandra and XMM-Newton X-ray Observatories as...

Psr is involved in regulation of glucan production, and double deficiency of BrpA and Psr is lethal in Streptococcus mutans.

Science.gov (United States)

Bitoun, Jacob P; Liao, Sumei; McKey, Briggs A; Yao, Xin; Fan, Yuwei; Abranches, Jacqueline; Beatty, Wandy L; Wen, Zezhang T

2013-03-01

Streptococcus mutans, the primary causative agent of dental caries, contains two paralogues of the LytR-CpsA-Psr family proteins encoded by brpA and psr, respectively. Previous studies have shown that BrpA plays an important role in cell envelope biogenesis/homeostasis and affects stress responses and biofilm formation by Strep. mutans, traits critical to cariogenicity of this bacterium. In this study, a Psr-deficient mutant, TW251, was constructed. Characterization of TW251 showed that deficiency of Psr did not have any major impact on growth rate. However, when subjected to acid killing at pH 2.8, the survival rate of TW251 was decreased dramatically compared with the parent strain UA159. In addition, TW251 also displayed major defects in biofilm formation, especially during growth with sucrose. When compared to UA159, the biofilms of TW251 were mainly planar and devoid of extracellular glucans. Real-time-PCR and Western blot analyses revealed that deficiency of Psr significantly decreased the expression of glucosyltransferase C, a protein known to play a major role in biofilm formation by Strep. mutans. Transmission electron microscopy analysis showed that deficiency of BrpA caused alterations in cell envelope and cell division, and the most significant defects were observed in TW314, a Psr-deficient and BrpA-down mutant. No such effects were observed with Psr mutant TW251 under similar conditions. These results suggest that while there are similarities in functions between BrpA and Psr, distinctive differences also exist between these two paralogues. Like Bacillus subtilis but different from Staphylococcus aureus, a functional BrpA or Psr is required for viability in Strep. mutans.

Pulsar velocity observations: Correlations, interpretations, and discussion

International Nuclear Information System (INIS)

Helfand, D.J.; Tademaru, E.

1977-01-01

From an examination of the current sample of 12 pulsars with measured proper motions and the z-distribution of the much larger group of over 80 sources with measured period derivatives, we develop a self-consistent picture of pulsar evolution. The apparent tendency of pulsars to move parallel to the galactic plane is explained as the result of various selection effects. A method for calculating the unmeasurable radial velocity of a pulsar is presented; it is shown that the total space velocities thus obtained are consistent with the assumption of an extreme Population I origin for pulsars which subsequently move away from the plane with a large range of velocities. The time scale for pulsar magnetic field decay is derived from dynamical considerations. A strong correlation of the original pulsar field strength with the magnitude of pulsar velocity is discussed. This results in the division of pulsars into two classes: Class A sources characterized by low space velocities, a small scale height, and low values of P 0 P 0 ; and Class B sources with a large range of velocities (up to 1000 km s -1 ), a much greater scale height, and larger values of initial field strength. It is postulated that Class A sources originate in tight binaries where their impulse acceleration at birth is insufficient to remove them from the system, while the Class B sources arise from single stars or loosely bound binaries and are accelerated to high velocities by their asymmetric radiation force. The evolutionary picture which is developed is shown to be consistent with a number of constraints imposed by supernova rates, the relative frequency of massive binaries and Class A sources, theoretical field-decay times, and the overall pulsar galactic distribution

Pulsar Magnetospheres and Pulsar Winds

OpenAIRE

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.

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.

Rotational and X-ray luminosity evolution of high-B radio pulsars

Science.gov (United States)

Benli, Onur; Ertan, Ünal

2018-05-01

In continuation of our earlier work on the long-term evolution of the so-called high-B radio pulsars (HBRPs) with measured braking indices, we have investigated the long-term evolution of the remaining five HBRPs for which braking indices have not been measured yet. This completes our source-by-source analyses of HBRPs in the fallback disc model that was also applied earlier to anomalous X-ray pulsars (AXPs), soft gamma repeaters (SGRs), and dim isolated neutron stars (XDINs). Our results show that the X-ray luminosities and the rotational properties of these rather different neutron star populations can be acquired by neutron stars with fallback discs as a result of differences in their initial conditions, namely the initial disc mass, initial period and the dipole field strength. For the five HBRPs, unlike for AXPs, SGRs and XDINs, our results do not constrain the dipole field strengths of the sources. We obtain evolutionary paths leading to the properties of HBRPs in the propeller phase with dipole fields sufficiently strong to produce pulsed radio emission.

Pulsar perimetry in the diagnosis of early glaucoma.

Science.gov (United States)

Zeppieri, Marco; Brusini, Paolo; Parisi, Lucia; Johnson, Chris A; Sampaolesi, Roberto; Salvetat, Maria Letizia

2010-01-01

To assess the ability of Pulsar perimetry (Pulsar) in detecting early glaucomatous visual field (VF) damage in comparison with Frequency Doubling Technology (FDT), Scanning Laser Polarimetry (SLP, GDx VCC), and Heidelberg Retina Tomography (HRT). Prospective observational cross-sectional case study. This multicenter study included: 87 ocular hypertensives (OHT); 67 glaucomatous optic neuropathy (GON) patients; 75 primary open-angle glaucoma (POAG) patients; and 90 normals. All patients underwent standard automated perimetry (SAP) HFA 30-2, Pulsar T30W, FDT N-30, HRT II, and GDx VCC. Area under Receiver Operating Characteristic Curves (AROCs) for discriminating between healthy and glaucomatous eyes and agreement among instruments were determined. The best parameters for Pulsar, FDT, HRT, and GDx were, respectively: loss variance square root; no. of areas with PPulsar (AROC, 0.90) appeared comparable with FDT (0.89) and significantly better than HRT (0.82) and GDx (0.79). For GON, Pulsar ability (0.74) was higher than GDx (0.69) and lower than FDT (0.80) and HRT (0.83). The agreement among instruments ranged from 0.12 to 0.56. Pulsar test duration was significantly shorter than SAP and FDT (PPulsar T30W test is a rapid and easy perimetric method, showing higher sensitivity than SAP in detecting early glaucomatous VF loss. Its diagnostic ability is good for detecting early perimetric POAG eyes and fair for GON eyes. Pulsar performance was comparable with FDT, HRT, and GDx, even if the agreement between instruments was poor to fair. Copyright 2010 Elsevier Inc. All rights reserved.

Radio pulsar death lines to SGRs/AXPs and white dwarfs pulsars

Energy Technology Data Exchange (ETDEWEB)

Lobato, Ronaldo V.; Malheiro, M. [Departamento de Física, Instituto Tecnológico de Aeronáutica, ITA - DCTA, Vila das Acácias, São José dos Campos, 12228-900 SP (Brazil); Coelho, J. G. [INPE - Instituto Nacional de Pesquisas Espaciais, Divisão de Astrofísica, Av. dos Astronautas 1758, São José dos Campos, 12227-010 SP (Brazil)

2015-12-17

Recently, an alternative model based on white dwarfs pulsars has been proposed to explain a class of pulsars known as Soft Gamma Repeaters (SGR) and Anomalus X-Ray Pulsars (AXP) [1], usually named as magnetars. In this model, the magnetized white dwarfs can have surface magnetic field B ∼ 10{sup 7} − 10{sup 10} G and rotate very fast with angular frequencies Ω ∼ 1 rad/s, allowing them to produce large electromagnetic (EM) potentials and generate electron-positron pairs. These EM potentials are comparable with the ones of neutron star pulsars with strong magnetic fields and even larger. In this study we consider two possible processes associated with the particle acceleration, both of them are common used to explain radio emission in neutron star pulsars: in the first process the pair production happens near to the star polar caps, i.e. inside of the light cylinder where magnetic field lines are closed; in the second one the creation of pair happens in the outer magnetosphere, i.e. far away of the star surface where magnetic field lines are open [2]. The analysis of the possibility of radio emission were done for 23 SGRs/AXPs of the McGill Online Magnetar Catalog [3] that contains the current information available on these sources. The results of this work show that the model where the particles production occur in the outer magnetosphere emission “o2” is the process compatible with the astronomical observations of absence of radio emission for almost all SGRs/AXPs when these sources are understood as white dwarf pulsars. Our work is a first attempted to find an explanation for the puzzle why for almost all the SGRs/AXPs was expected radio emission, but it was observed in only four of them. These four sources, as it was suggested recently [4], seem to belong to an high magnetic field neutron star pulsar category, different from all the others SGRs/AXPs that our work indicate to belong to a new class of white dwarf pulsars, very fast and magnetized.

Detection of sodium in the atmosphere of WASP-69b

Science.gov (United States)

Casasayas-Barris, N.; Palle, E.; Nowak, G.; Yan, F.; Nortmann, L.; Murgas, F.

2017-12-01

Context. Transit spectroscopy is one of the most commonly used methods to characterize exoplanets' atmospheres. From the ground, these observations are very challenging due to the terrestrial atmosphere and its intrinsic variations, but high-spectral-resolution observations overcome this difficulty by resolving the spectral lines and taking advantage of the different Doppler velocities of the Earth, the host star, and the exoplanet. Aims: We analyze the transmission spectrum around the Na I doublet at 589 nm of the extrasolar planet WASP-69b, a hot Jupiter orbiting a K-type star with a period of 3.868 days, and compare the analysis to that of the well-known hot Jupiter HD 189733b. We also present the analysis of the Rossiter-McLaughlin (RM) effect for WASP-69b. Methods: We observed two transits of WASP-69b with the High Accuracy Radial velocity Planet Searcher (HARPS-North) spectrograph (R = 115 000) at the Telescopio Nazionale Galileo (TNG). We perform a telluric contamination subtraction based on the comparison between the observed spectra and a telluric water model. Then, the common steps of the differential spectroscopy are followed to extract the transmission spectrum. The method is tested with archival transit data of the extensively studied exoplanet HD 189733b, obtained with the HARPS-South spectrograph at ESO 3.6 m telescope, and then applied to WASP-69b data. Results: For HD 189733b, we spectrally resolve the Na I doublet and measure line contrasts of 0.72 ± 0.05% (D2) and 0.51 ± 0.05% (D1), and full width half maximum (FWHM) values of 0.64 ± 0.04 Å (D2) and 0.60 ± 0.06 Å (D1), in agreement with previously published results. For WASP-69b only the contrast of the D2 line can be measured (5.8 ± 0.3%). This corresponds to a detection at the 5σ-level of excess absorption of 0.5 ± 0.1% in a passband of 1.5 Å. A net blueshift of 0.04 Å is measured for HD 189733b and no shift is obtained for WASP-69b. By measuring the RM effect, we get an angular

THE VLT-FLAMES TARANTULA SURVEY: THE FASTEST ROTATING O-TYPE STAR AND SHORTEST PERIOD LMC PULSAR-REMNANTS OF A SUPERNOVA DISRUPTED BINARY?

Energy Technology Data Exchange (ETDEWEB)

Dufton, P. L.; Dunstall, P. R.; Fraser, M. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Evans, C. J. [UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Brott, I. [University of Vienna, Department of Astronomy, Tuerkenschanzstr. 17, A-1180 Vienna (Austria); Cantiello, M.; Langer, N. [Argelander Institut fuer Astronomie der Universitaet Bonn, Auf dem Huegel 71, 53121 Bonn (Germany); De Koter, A.; Sana, H. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); De Mink, S. E. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Henault-Brunet, V.; Taylor, W. D. [Scottish Universities Physics Alliance, Institute for Astronomy, University of Edinburgh, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Howarth, I. D. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Lennon, D. J. [ESA, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Markova, N., E-mail: p.dufton@qub.ac.uk [Institute of Astronomy with NAO, Bulgarian Academy of Sciences, P.O. Box 136, 4700 Smoljan (Bulgaria)

2011-12-10

We present a spectroscopic analysis of an extremely rapidly rotating late O-type star, VFTS102, observed during a spectroscopic survey of 30 Doradus. VFTS102 has a projected rotational velocity larger than 500 km s{sup -1} and probably as large as 600 km s{sup -1}; as such it would appear to be the most rapidly rotating massive star currently identified. Its radial velocity differs by 40 km s{sup -1} from the mean for 30 Doradus, suggesting that it is a runaway. VFTS102 lies 12 pc from the X-ray pulsar PSR J0537-6910 in the tail of its X-ray diffuse emission. We suggest that these objects originated from a binary system with the rotational and radial velocities of VFTS102 resulting from mass transfer from the progenitor of PSR J0537-691 and the supernova explosion, respectively.

DISCOVERY OF PULSED γ-RAYS FROM PSR J0034-0534 WITH THE FERMI LARGE AREA TELESCOPE: A CASE FOR CO-LOCATED RADIO AND γ-RAY EMISSION REGIONS

International Nuclear Information System (INIS)

Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bonamente, E.; Brigida, M.; Bruel, P.

2010-01-01

Millisecond pulsars (MSPs) have been firmly established as a class of γ-ray emitters via the detection of pulsations above 0.1 GeV from eight MSPs by the Fermi Large Area Telescope (LAT). Using 13 months of LAT data, significant γ-ray pulsations at the radio period have been detected from the MSP PSR J0034-0534, making it the ninth clear MSP detection by the LAT. The γ-ray light curve shows two peaks separated by 0.274 ± 0.015 in phase which are very nearly aligned with the radio peaks, a phenomenon seen only in the Crab pulsar until now. The ≥0.1 GeV spectrum of this pulsar is well fit by an exponentially cutoff power law with a cutoff energy of 1.8 ± 0.6 ± 0.1 GeV and a photon index of 1.5 ± 0.2 ± 0.1, first errors are statistical and second are systematic. The near-alignment of the radio and γ-ray peaks strongly suggests that the radio and γ-ray emission regions are co-located and both are the result of caustic formation.

A search for TeV gamma-ray emission from SNRs, pulsars and unidentified GeV sources in the Galactic plane in the longitude range between -2 deg and 85 deg.

Science.gov (United States)

Aharonian, F. A.; Akhperjanian, A. G.; Beilicke, M.; Bernloehr, K.; Bojahr, H.; Bolz, O.; Boerst, H.; Coarasa, T.; Contreras, J. L.; Cortina, J.; Denninghoff, S.; Fonseca, V.; Girma, M.; Goetting, N.; Heinzelmann, G.; Hermann, G.; Heusler, A.; Hofmann, W.; Horns, D.; Jung, I.; Kankanyan, R.; Kestel, M.; Kettler, J.; Kohnle, A.; Konopelko, A.; Kornmeyer, H.; Kranich, D.; Krawczynski, H.; Lampeitl, H.; Lopez, M.; Lorenz, E.; Lucarelli, F.; Mang, O.; Meyer, H.; Mirzoyan, R.; Moralejo, A.; Ona, E.; Panter, M.; Plyasheshnikov, A.; Puehlhofer, G.; Rauterberg, G.; Reyes, R.; Rhode, W.; Ripken, J.; Roehring, A.; Rowell, G. P.; Sahakian, V.; Samorski, M.; Schilling, M.; Siems, M.; Sobzynska, D.; Stamm, W.; Tluczykont, M.; Voelk, H. J.; Wiedner, C. A.; Wittek, W.

2002-12-01

Using the HEGRA system of imaging atmospheric Cherenkov telescopes, one quarter of the Galactic plane (-2o < l < 85o) was surveyed for TeV gamma-ray emission from point sources and moderately extended sources (φ <= 0.8o). The region covered includes 86 known pulsars (PSR), 63 known supernova remnants (SNR) and nine GeV sources, representing a significant fraction of the known populations. No evidence for emission of TeV gamma radiation was detected, and upper limits range from 0.15 Crab units up to several Crab units, depending on the observation time and zenith angles covered. The ensemble sums over selected SNR and pulsar subsamples and over the GeV-sources yield no indication of emission from these potential sources. The upper limit for the SNR population is 6.7% of the Crab flux and for the pulsar ensemble is 3.6% of the Crab flux.

Gigahertz-peaked spectra pulsars in Pulsar Wind Nebulae

Science.gov (United States)

Basu, R.; RoŻko, K.; Kijak, J.; Lewandowski, W.

2018-04-01

We have carried out a detailed study of the spectral nature of six pulsars surrounded by pulsar wind nebulae (PWNe). The pulsar flux density was estimated using the interferometric imaging technique of the Giant Metrewave Radio Telescope at three frequencies 325, 610, and 1280 MHz. The spectra showed a turnover around gigahertz frequency in four out of six pulsars. It has been suggested that the gigahertz-peaked spectrum (GPS) in pulsars arises due to thermal absorption of the pulsar emission in surrounding medium like PWNe, H II regions, supernova remnants, etc. The relatively high incidence of GPS behaviour in pulsars surrounded by PWNe imparts further credence to this view. The pulsar J1747-2958 associated with the well-known Mouse nebula was also observed in our sample and exhibited GPS behaviour. The pulsar was detected as a point source in the high-resolution images. However, the pulsed emission was not seen in the phased-array mode. It is possible that the pulsed emission was affected by extreme scattering causing considerable smearing of the emission at low radio frequencies. The GPS spectra were modelled using the thermal free-free absorption and the estimated absorber properties were largely consistent with PWNe. The spatial resolution of the images made it unlikely that the point source associated with J1747-2958 was the compact head of the PWNe, but the synchrotron self-absorption seen in such sources was a better fit to the estimated spectral shape.

Swift , XMM - Newton , and NuSTAR Observations of PSR J2032+4127/MT91 213

Energy Technology Data Exchange (ETDEWEB)

Li, K. L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Kong, A. K. H. [Astrophysics, Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Tam, P. H. T. [School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082 (China); Hou, X. [Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming 650216 (China); Takata, J. [Institute of Particle Physics and Astronomy, Huazhong University of Science and Technology (China); Hui, C. Y., E-mail: liliray@pa.msu.edu [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

2017-07-10

We report our recent Swift , NuSTAR , and XMM - Newton X-ray and Lijiang optical observations on PSR J2032+4127/MT91 213, the γ -ray binary candidate with a period of 45–50 years. The coming periastron of the system was predicted to be in 2017 November, around which high-energy flares from keV to TeV are expected. Recent studies with Chandra and Swift X-ray observations taken in 2015/2016 showed that its X-ray emission has been brighter by a factors of ∼10 than that before 2013, probably revealing some ongoing activities between the pulsar wind and the stellar wind. Our new Swift /XRT lightcurve shows no strong evidence of a single vigorous brightening trend, but rather several strong X-ray flares on weekly to monthly timescales with a slowly brightening baseline, namely the low state. The NuSTAR and XMM - Newton observations taken during the flaring and the low states, respectively, show a denser environment and a softer power-law index during the flaring state, implying that the pulsar wind interacted with the stronger stellar winds of the companion to produce the flares. These precursors would be crucial in studying the predicted giant outburst from this extreme γ -ray binary during the periastron passage in late 2017.

Sampling the Radio Transient Universe: Studies of Pulsars and the Search for Extraterrestrial Intelligence

Science.gov (United States)

Chennamangalam, Jayanth

clusters Terzan 5, 47 Tucanae, and M 28. Applying Bayesian statistics to our data set consisting of the number of detected pulsars, their flux densities, and the amount of diffuse radio emission from the direction of these clusters, we show that the number of potentially observable pulsars in Terzan 5 should be within a 95 per cent credible interval of 147+112-65 For 47 Tucanae and M 28, our results are 83+54-35 and 100+91-52 , spectively. We also constrain the luminosity function parameters for the pulsars in these clusters. The Galactic center pulsar population has been an interesting target for various studies, especially given that only one pulsar has been detected in the region, when we expect hundreds of pulsars to be present. In this work, we use the scattering measurements from recent observations of PSR J1745--2900, the Galactic center pulsar, and show that the size of the potentially observable pulsar population has a conservative upper limit of ~200. We show that the observational results so far are consistent with this number and make predictions for future radio pulsar surveys of the region. The Versatile GBT Astronomical Spectrometer (VEGAS) is a heterogeneous instrument used mainly for pulsar studies with the Green Bank Telescope. I describe our work on the GPU spectrometer that we developed as part of VEGAS. The GPU code supports a dual-polarization bandwidth of up to 600 MHz. In the field of SETI, I discuss two works. SERENDIP VI is a heterogeneous SETI spectrometer to be installed both at the Green Bank Telescope and at the Arecibo Observatory. In this work, we describe the design of the GPU spectrometer that forms part of SERENDIP VI. In the second work, we speculate on a novel search strategy for SETI, based on the idea that technological civilizations lacking the advancement required to build high-powered beacons may choose to build a modulator situated around a nearby pulsar, depending on whether it is energetically favorable. We discuss observational

SUPERFLUID VORTEX UNPINNING AS A COHERENT NOISE PROCESS, AND THE SCALE INVARIANCE OF PULSAR GLITCHES

International Nuclear Information System (INIS)

Melatos, A.; Warszawski, L.

2009-01-01

The scale-invariant glitch statistics observed in individual pulsars (exponential waiting-time and power-law size distributions) are consistent with a critical self-organization process, wherein superfluid vortices pin metastably in macroscopic domains and unpin collectively via nearest-neighbor avalanches. Macroscopic inhomogeneity emerges naturally if pinning occurs at crustal faults. If, instead, pinning occurs at lattice sites and defects, which are macroscopically homogeneous, we show that an alternative, noncritical self-organization process operates, termed coherent noise, wherein the global Magnus force acts uniformly on vortices trapped in a range of pinning potentials and undergoing thermal creep. It is found that vortices again unpin collectively, but not via nearest-neighbor avalanches, and that, counterintuitively, the resulting glitch sizes are scale invariant, in accord with observational data. A mean-field analytic theory of the coherent noise process, supported by Monte Carlo simulations, yields a power-law size distribution, between the smallest and largest glitch, with exponent a in the range -2 ≤ a ≤ 0. When the theory is fitted to data from the nine most active pulsars, including the two quasi-periodic glitchers PSR J0537-6910 and PSR J0835-4510, it directly constrains the distribution of pinning potentials in the star, leading to two conclusions: (1) the potentials are broadly distributed, with the mean comparable to the standard deviation; and (2) the mean potential decreases with characteristic age. Fitting the theory to the data also constrains the pinned vortex fraction and the rate of thermal creep. An observational test is proposed to discriminate between nearest-neighbor avalanches and coherent noise: the latter process predicts a statistical excess of large glitches ('aftershocks') following a large glitch, whereas the former process does not. Its discriminatory power is discussed under various microphysical scenarios.

Supernova remnant S147 and its associated neutron star(s)

OpenAIRE

Gvaramadze, V. V.

2005-01-01

The supernova remnant S147 harbors the pulsar PSR J0538+2817 whose characteristic age is more than an order of magnitude greater than the kinematic age of the system (inferred from the angular offset of the pulsar from the geometric center of the supernova remnant and the pulsar proper motion). To reconcile this discrepancy we propose that PSR J0538+2817 could be the stellar remnant of the first supernova explosion in a massive binary system and therefore could be as old as its characteristic...

Pulsar astronomy

International Nuclear Information System (INIS)

Lyne, A.G.; Graham-Smith, F.

1990-01-01

This account of the properties of pulsars tells an exciting story of discovery in modern astronomy. Pulsars, discovered in 1967, now take their place in a very wide range of astrophysics. They are one of the endpoints of stellar evolution, in which the core of a star collapses to a rapidly spinning neutron star a few kilometres in size. This book is an introductory account for those entering the field. It introduces the circumstances of the discovery and gives an overview of pulsar astrophysics. There are chapters on search techniques, distances, pulse timing, the galactic population of pulsars, binary and millisecond pulsars, geometry and physics of the emission regions, and applications to the interstellar medium. An important feature of this book is the inclusion of an up-to-date catalogue of all known pulsars. (author)

A novel look at the pulsar force-free magnetosphere

Science.gov (United States)

Petrova, S. A.; Flanchik, A. B.

2018-03-01

The stationary axisymmetric force-free magnetosphere of a pulsar is considered. We present an exact dipolar solution of the pulsar equation, construct the magnetospheric model on its basis and examine its observational support. The new model has toroidal rather than common cylindrical geometry, in line with that of the plasma outflow observed directly as the pulsar wind nebula at much larger spatial scale. In its new configuration, the axisymmetric magnetosphere consumes the neutron star rotational energy much more efficiently, implying re-estimation of the stellar magnetic field, B_{new}0=3.3×10^{-4}B/P, where P is the pulsar period. Then the 7-order scatter of the magnetic field derived from the rotational characteristics of the pulsars observed appears consistent with the \\cotχ-law, where χ is a random quantity uniformly distributed in the interval [0,π/2]. Our result is suggestive of a unique actual magnetic field strength of the neutron stars along with a random angle between the magnetic and rotational axes and gives insight into the neutron star unification on the geometrical basis.

Arecibo pulsar survey using ALFA. III. Precursor survey and population synthesis

Energy Technology Data Exchange (ETDEWEB)

Swiggum, J. K.; Lorimer, D. R.; McLaughlin, M. A.; Bates, S. D.; Senty, T. R. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Champion, D. J.; Lazarus, P. [Max-Planck-Institut für Radioastronomie, D-53121 Bonn (Germany); Ransom, S. M. [NRAO, Charlottesville, VA 22903 (United States); Brazier, A.; Chatterjee, S.; Cordes, J. M. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Hessels, J. W. T. [ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Nice, D. J. [Department of Physics, Lafayette College, Easton, PA 18042 (United States); Ellis, J.; Allen, B. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee WI 53211 (United States); Bhat, N. D. R. [Center for Astrophysics and Supercomputing, Swinburne University, Hawthorn, Victoria 3122 (Australia); Bogdanov, S.; Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Crawford, F. [Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003 (United States); Deneva, J. S. [Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612 (United States); and others

2014-06-01

The Pulsar Arecibo L-band Feed Array (PALFA) Survey uses the ALFA 7-beam receiver to search both inner and outer Galactic sectors visible from Arecibo (32° ≲ ℓ ≲ 77° and 168° ≲ ℓ ≲ 214°) close to the Galactic plane (|b| ≲ 5°) for pulsars. The PALFA survey is sensitive to sources fainter and more distant than have previously been seen because of Arecibo's unrivaled sensitivity. In this paper we detail a precursor survey of this region with PALFA, which observed a subset of the full region (slightly more restrictive in ℓ and |b| ≲ 1°) and detected 45 pulsars. Detections included 1 known millisecond pulsar and 11 previously unknown, long-period pulsars. In the surveyed part of the sky that overlaps with the Parkes Multibeam Pulsar Survey (36° ≲ ℓ ≲ 50°), PALFA is probing deeper than the Parkes survey, with four discoveries in this region. For both Galactic millisecond and normal pulsar populations, we compare the survey's detections with simulations to model these populations and, in particular, to estimate the number of observable pulsars in the Galaxy. We place 95% confidence intervals of 82,000 to 143,000 on the number of detectable normal pulsars and 9000 to 100,000 on the number of detectable millisecond pulsars in the Galactic disk. These are consistent with previous estimates. Given the most likely population size in each case (107,000 and 15,000 for normal and millisecond pulsars, respectively), we extend survey detection simulations to predict that, when complete, the full PALFA survey should have detected 1000{sub −230}{sup +330} normal pulsars and 30{sub −20}{sup +200} millisecond pulsars. Identical estimation techniques predict that 490{sub −115}{sup +160} normal pulsars and 12{sub −5}{sup +70} millisecond pulsars would be detected by the beginning of 2014; at the time, the PALFA survey had detected 283 normal pulsars and 31 millisecond pulsars, respectively. We attribute the deficiency in normal pulsar

Pulsar magnetospheres

International Nuclear Information System (INIS)

Kennel, C.F.; Fujimura, F.S.; Pellat, R.

1979-01-01

The structure of both the interior and exterior pulsar magnetospehere depends upon the strength of its plasma source near the surface of the star. We review magnetospheric models in the light of a vacuum pair-production source model proposed by Sturrock, and Ruderman and Sutherland. This model predicts the existence of a cutoff, determined by the neutron star's spin rate and magnetic field strength, beyond which coherent radio emission is no longer possible. The observed distribution of pulsar spin periods and period derivates, and the distribution of pulsars with missing radio pulses, is quantitatively consistent with the pair production threshold, when its variation of neutron star radius and moment of interia with mass is taken into account. All neutron stars observed as pulsars can have relativistic magneto-hydrodynamic wind exterior magnetospheres. The properties of the wind can be directly related to those of the pair production source. Radio pulsars cannot have relativistic plasma wave exterior magnetospheres. On the other hand, most erstwhile pulsars in the galaxy are probably halo objects that emit weak fluxes of energetic photons that can have relativistic wave exterior magnetospheres. Extinct pulsars have not been yet observed. (orig.)

Pulsars at Parkes

OpenAIRE

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 ...

Expansion and Brightness Changes in the Pulsar-wind Nebula in the Composite Supernova Remnant Kes 75

Science.gov (United States)

Reynolds, Stephen P.; Borkowski, Kazimierz J.; Gwynne, Peter H.

2018-04-01

We report new Chandra X-ray observations of the shell supernova remnant Kes 75 (G29.7‑0.3) containing a pulsar and pulsar-wind nebula (PWN). Expansion of the PWN is apparent across four epochs—2000, 2006, 2009, and 2016. We find an expansion rate between 2000 and 2016 of the northwest edge of the PWN of 0.249% ± 0.023% yr‑1, for an expansion age R/(dR/dt) of 400 ± 40 yr and an expansion velocity of about 1000 km s‑1. We suggest that the PWN is expanding into an asymmetric nickel bubble in a conventional Type IIP supernova. Some acceleration of the PWN expansion is likely, giving a true age of 480 ± 50 yr. The pulsar’s birth luminosity was larger than the current value by a factor of 3–8, while the initial period was within a factor of 2 of its current value. We confirm directly that Kes 75 contains the youngest known PWN, and hence the youngest known pulsar. The pulsar PSR J1846‑0258 has a spindown-inferred magnetic field of 5 × 1013 G; in 2006, it emitted five magnetar-like short X-ray bursts, but its spindown luminosity has not changed significantly. However, the flux of the PWN has decreased by about 10% between 2009 and 2016, almost entirely in the northern half. A bright knot has declined by 30% since 2006. During this time, the photon indices of the power-law models did not change. This flux change is too rapid to be due to normal PWN evolution in one-zone models.

The spatial distribution and birth-rate of pulsars

International Nuclear Information System (INIS)

Guseinov, O.H.; Kasumov, F.K.

1978-01-01

The distribution of pulsars in the wide range of observed luminosities has been obtained. It is shown that the function of luminosity (FL) within 3 x 10 26 30 erg s -1 conforms to the power law dN/dL - c 1 Lsup(-γ), where γ = 1.76 +- 0.06. For L 26 erg s -1 , FL changes its inclination and may be approximated as dN/dL approximately Lsup(-γ 1 ), where γ 1 = 0.7 +- 0.2. On the basis of statistical selection, including all pulsars with L > 3 x 10 28 erg s -1 , the distribution of pulsars has been investigated as a function of the distance to the centre R and galactic plane Z. The obtained laws of the radial and Z-distribution of pulsars and galactic supernova remnants and also the radial distribution of types I and II supernovae in the models Sb and Sc support the hypothesis of their origin from the objects of the flat subsystem of Population I. Since there are some arguments in favour of a possible connection between supernovae I and the objects of the intermediate component of the Galaxy, one cannot exclude the possibility of supernovae explosions at the end of the evolution of stars with masses of 1.5-2 Msub(sun). It is also shown that pulsars and supernovae are evidently objects that are connected genetically, and, within the limits of statistical error, they have a similar birth-rate. The empirical law of the evolution of a pulsar's luminosity as a function of its true age has been obtained, according to which L = c 2 tsup(-β), where c 2 = (3.69+- 3.4) x 10 35 ,β = 1.32 +- 0.11. (Auth.)

UPPER LIMITS ON PULSED RADIO EMISSION FROM THE 6.85 s X-RAY PULSAR XTE J0103-728 IN THE SMALL MAGELLANIC CLOUD

International Nuclear Information System (INIS)

Crawford, Fronefield; Devour, Brian M.; Takacs, Brian P.; Lorimer, Duncan R.; Kondratiev, Vladislav I.

2009-01-01

X-ray pulsations with a 6.85 s period were recently detected in the Small Magellanic Cloud (SMC) and were subsequently identified as originating from the Be/X-ray binary system XTE J0103-728. The recent localization of the source of the X-ray emission has made a targeted search for radio pulsations from this source possible. The detection of pulsed radio emission from XTE J0103-728 would make it only the second system after PSR B1259-63 that is both a Be/X-ray binary and a radio pulsar. We observed XTE J0103-728 in 2008 February with the Parkes 64 m radio telescope soon after the identification of the source of X-ray pulsations was reported in order to search for corresponding radio pulsations. We used a continuous 6.4 hr observation with a 256 MHz bandwidth centered at 1390 MHz using the center beam of the Parkes multibeam receiver. In the subsequent data analysis, which included a folding search, a Fourier search, a fast-folding algorithm search, and a single pulse search, no pulsed signals were found for trial dispersion measures (DMs) between 0 and 800 pc cm -3 . This DM range easily encompasses the expected values for sources in the SMC. We place an upper limit of ∼45 mJy kpc 2 on the luminosity of periodic radio emission from XTE J0103-728 at the epoch of our observation, and we compare this limit to a range of luminosities measured for PSR B1259-63, the only Be/X-ray binary currently known to emit radio pulses. We also compare our limit to the radio luminosities of neutron stars having similarly long spin periods to XTE J0103-728. Since the radio pulses from PSR B1259-63 are eclipsed and undetectable during the portion of the orbit near periastron, repeated additional radio search observations of XTE J0103-728 may be valuable if it is undergoing similar eclipsing and if such observations are able to sample the orbital phase of this system well.

A CHANDRA OBSERVATION OF SNR 0540 - 697

International Nuclear Information System (INIS)

Seward, F. D.; Williams, R. M.; Chu, Y.-H.; Gruendl, R. A.; Dickel, J. R.

2010-01-01

This paper describes a Chandra observation of SNR 0540 - 697 within the H II complex N159 in the Large Magellanic Cloud (LMC). Scattering from the nearby bright source LMC X-1, which obscures the western edge of the remnant, has been removed. Larger than previously believed, the 2.'0 x 2.'8 remnant is defined by optical filaments and two lobes of X-ray emission. A band of intervening material absorbs X-rays from the central part of the remnant. The N Lobe of the remnant is relatively bright and well defined, while emission from the S Lobe is much weaker. There is structure within the N Lobe but no clear X-ray emission from an outer shell indicating a shock in the interstellar medium. The X-ray spectrum is thermal with emission lines from Fe, Mg, and Si. The observed temperature and luminosity of the hot gas are 0.6 keV and 6 x 10 35 erg s -1 , respectively. These are consistent with characteristics expected for older remnants. There is also diffuse thermal X-ray emission north of N159 extending into N160, evidence for a larger remnant or bubble.

CHANDRA OBSERVATIONS OF THE HIGH-MAGNETIC-FIELD RADIO PULSAR J1718-3718

International Nuclear Information System (INIS)

Zhu, W. W.; Kaspi, V. M.; Ng, C.-Y.; McLaughlin, M. A.; Pavlov, G. G.; Manchester, R. N.; Gaensler, B. M.; Woods, P. M.

2011-01-01

High-magnetic-field pulsars represent an important class of objects for studying the relationship between magnetars and radio pulsars. Here we report on four Chandra observations of the high-magnetic-field pulsar J1718-3718 (B = 7.4 x 10 13 G) taken in 2009 as well as a reanalysis of 2002 Chandra observations of the region. We also report an improved radio position for this pulsar based on ATCA observations. We detect X-ray pulsations at the pulsar's period in the 2009 data, with a pulsed fraction of 52% ± 13% in the 0.8-2.0 keV band. We find that the X-ray pulse is aligned with the radio pulse. The data from 2002 and 2009 show consistent spectra and fluxes: a merged overall spectrum is well fit by a blackbody of temperature 186 +19 -18 eV, slightly higher than predicted by standard cooling models; however, the best-fit neutron star atmosphere model is consistent with standard cooling. We find the bolometric luminosity L ∞ bb = 4 +5 -2 x 10 32 erg s -1 ∼0.3 E-dot for a distance of 4.5 kpc. We compile measurements of the temperatures of all X-ray-detected high-B pulsars as well as those of low-B radio pulsars and find evidence for the former being hotter on average than the latter.

A Refined Search for Pulsations in White Dwarf Companions to Millisecond Pulsars

Science.gov (United States)

Kilic, Mukremin; Hermes, J. J.; Córsico, A. H.; Kosakowski, Alekzander; Brown, Warren R.; Antoniadis, John; Calcaferro, Leila M.; Gianninas, A.; Althaus, Leandro G.; Green, M. J.

2018-06-01

We present optical high-speed photometry of three millisecond pulsars with low-mass (<0.3 M⊙) white dwarf companions, bringing the total number of such systems with follow-up time-series photometry to five. We confirm the detection of pulsations in one system, the white dwarf companion to PSR J1738+0333, and show that the pulsation frequencies and amplitudes are variable over many months. A full asteroseismic analysis for this star is under-constrained, but the mode periods we observe are consistent with expectations for a M⋆ = 0.16 - 0.19M⊙ white dwarf, as suggested from spectroscopy. We also present the empirical boundaries of the instability strip for low-mass white dwarfs based on the full sample of white dwarfs, and discuss the distinction between pulsating low-mass white dwarfs and subdwarf A/F stars.

Experimental Constraints on γ-Ray Pulsar Gap Models and the Pulsar GeV to Pulsar Wind Nebula TeV Connection

Science.gov (United States)

Abeysekara, A. U.; Linnemann, J. T.

2015-05-01

The pulsar emission mechanism in the gamma ray energy band is poorly understood. Currently, there are several models under discussion in the pulsar community. These models can be constrained by studying the collective properties of a sample of pulsars, which became possible with the large sample of gamma ray pulsars discovered by the Fermi Large Area Telescope. In this paper we develop a new experimental multi-wavelength technique to determine the beaming factor ≤ft( {{f}{Ω }} \\right) dependance on spin-down luminosity of a set of GeV pulsars. This technique requires three input parameters: pulsar spin-down luminosity, pulsar phase-averaged GeV flux, and TeV or X-ray flux from the associated pulsar wind nebula (PWN). The analysis presented in this paper uses the PWN TeV flux measurements to study the correlation between {{f}{Ω }} and \\dot{E}. The measured correlation has some features that favor the Outer Gap model over the Polar Cap, Slot Gap, and One Pole Caustic models for pulsar emission in the energy range of 0.1-100 GeV, but one must keep in mind that these simulated models failed to explain many of the most important pulsar population characteristics. A tight correlation between the pulsar GeV emission and PWN TeV emission was also observed, which suggests the possibility of a linear relationship between the two emission mechanisms. In this paper we also discuss a possible mechanism to explain this correlation.

Rapidly Rising Optical Transients from the Birth of Binary Neutron Stars

Science.gov (United States)

Hotokezaka, Kenta; Kashiyama, Kazumi; Murase, Kohta

2017-11-01

We study optical counterparts of a new-born pulsar in a double neutron star system like PSR J0737-3039A/B. This system is believed to have ejected a small amount of mass of { O }(0.1 {M}⊙ ) at the second core-collapse supernova. We argue that the initial spin of the new-born pulsar can be determined by the orbital period at the time when the second supernova occurs. The spin angular momentum of the progenitor is expected to be similar to that of the He-burning core, which is tidally synchronized with the orbital motion, and then the second remnant may be born as a millisecond pulsar. If the dipole magnetic field strength of the nascent pulsar is comparable with that inferred from the current spin-down rate of PSR J0737-3039B, the initial spin-down luminosity is comparable to the luminosity of super-luminous supernovae. We consider thermal emission arising from the supernova ejecta driven by the relativistic wind from such a new-born pulsar. The resulting optical light curves have a rise time of ˜10 days and a peak luminosity of ˜1044 erg s-1. The optical emission may last for a month to several months, due to the reprocessing of X-rays and UV photons via photoelectric absorption. These features are broadly consistent with those of the rapidly rising optical transients. The high spin-down luminosity and small ejecta mass are favorable for the progenitor of the repeating fast radio burst, FRB 121102. We discuss a possible connection between new-born double pulsars and fast radio bursts.

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.

The paternal-sex-ratio (PSR) chromosome in natural populations of Nasonia (Hymenoptera Chalcidoidea)

NARCIS (Netherlands)

Beukeboom, L.W.; Werren, J.H.

2000-01-01

Selfish genetic elements may be important in promoting evolutionary change. Paternal sex ratio (PSR) is a selfish B chromosome that causes all-male families in the haplodiploid parasitic wasp Nasonia vitripennis, by inducing paternal genome loss in fertilized eggs. The natural distribution and

Gamma-Ray Pulsars Models and Predictions

CERN Document Server

Harding, A K

2001-01-01

Pulsed emission from gamma-ray pulsars originates inside the magnetosphere, from radiation by charged particles accelerated near the magnetic poles or in the outer gaps. In polar cap models, the high energy spectrum is cut off by magnetic pair production above an energy that is dependent on the local magnetic field strength. While most young pulsars with surface fields in the range B = 10^{12} - 10^{13} G are expected to have high energy cutoffs around several GeV, the gamma-ray spectra of old pulsars having lower surface fields may extend to 50 GeV. Although the gamma-ray emission of older pulsars is weaker, detecting pulsed emission at high energies from nearby sources would be an important confirmation of polar cap models. Outer gap models predict more gradual high-energy turnovers at around 10 GeV, but also predict an inverse Compton component extending to TeV energies. Detection of pulsed TeV emission, which would not survive attenuation at the polar caps, is thus an important test of outer gap models. N...

Pulsars today

International Nuclear Information System (INIS)

Graham-Smith, F.

1990-01-01

The theory concerning pulsars is reviewed, with particular attention to possible evolution, life cycle, and rejuvenation of these bodies. Quantum liquids, such as neutron superfluids, and evidence for the existence of superfluid vortices and other internal phenomena are considered with particular attention to the Crab pulsar. Rate of change of the rotation rate is measured and analyzed for the Crab pulsar and the implications of deviations in the pulse times from those of a perfect rotator are examined. Glitches, the sudden increase in rotation rate of a pulsar that has previously exhibited a steady slowdown, are discussed and it is suggested that the movement of the superfluid core relative to the crust is responsible for this phenomenon. It is noted that radio waves from pulsars can be used to determine the intensity and structure of interplanetary and interstellar gas turbulence and to provide a direct measure of the strength of the interstellar magnetic field

MEASURING THE MAGNETIC FIELD OF CORONAL MASS EJECTIONS NEAR THE SUN USING PULSARS

Energy Technology Data Exchange (ETDEWEB)

Howard, T. A. [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Stovall, K.; Dowell, J.; Taylor, G. B. [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM (United States); White, S. M., E-mail: howard@boulder.swri.edu [Air Force Research Laboratory, Space Vehicles Directorate, Albuquerque, NM (United States)

2016-11-10

The utility of Faraday rotation to measure the magnetic field of the solar corona and large-scale transients within is a small, yet growing field in solar physics. This is largely because it has been recognized as a potentially valuable frontier in space weather studies, because the ability to measure the intrinsic magnetic field within coronal mass ejections (CMEs) when they are close to the Sun is of great interest for understanding a key element of space weather. Such measurements have been attempted over the last few decades using radio signals from artificial sources (i.e., spacecraft on the far side of the Sun), but studies involving natural radio sources are scarce in the literature. We report on a preliminary study involving an attempt to detect the Faraday rotation of a CME that passed in front of a pulsar (PSR B0950+08) in 2015 August. We combine radio measurements with those from a broadband visible light coronagraph, to estimate the upper limit of the magnetic field of the CME when it was in the corona. We find agreement between different approaches for obtaining its density, and values that are consistent with those predicted from prior studies of CME density close to the Sun.

NuSTAR discovery of an unusually steady long-term spin-up of the Be binary 2RXP J130159.6-635806

DEFF Research Database (Denmark)

Krivonos, Roman A.; Tsygankov, Sergey S.; Lutovinov, Alexander A.

2015-01-01

We present spectral and timing analysis of NuSTAR observations of the accreting X-ray pulsar 2RXP J130159.6-635806. The source was serendipitously observed during a campaign focused on the gamma-ray binary PSR B1259-63 and was later targeted for a dedicated observation. The spectrum has a typical...

THE IDENTIFICATION OF THE X-RAY COUNTERPART TO PSR J2021+4026

Energy Technology Data Exchange (ETDEWEB)

Weisskopf, Martin C.; Elsner, Ronald F.; O' Dell, Stephen L.; Tennant, Allyn F. [NASA Marshall Space Flight Center, Space Science Office, VP62, Huntsville, AL 35812 (United States); Romani, Roger W. [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Razzano, Massimiliano [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Belfiore, Andrea; Saz Parkinson, Pablo; Ziegler, Marcus; Dormody, Michael [Santa Cruz Institute for Particle Physics, Department of Physics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Ray, Paul S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kerr, Matthew [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305 (United States); Harding, Alice [Astrophysics Science Division, NASA Goddard Space Flight Center, Code 663, Greenbelt, MD 20771 (United States); Swartz, Douglas A. [Universities Space Research Association, NASA Marshall Space Flight Center, Space Science Office, VP62, Huntsville, AL 35812 (United States); Carraminana, Alberto [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro 1, Tonantzintla, Puebla 72840 (Mexico); Becker, Werner; Kanbach, Gottfried [Max-Planck-Institut fuer extraterrestrische Physik, 85741 Garching bei Muenchen (Germany); De Luca, Andrea [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Thompson, David J. [Astroparticle Physics Laboratory, NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States)

2011-12-10

We report the probable identification of the X-ray counterpart to the {gamma}-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20{sup h}21{sup m}30.{sup s}733, decl. +40 Degree-Sign 26'46.''04 (J2000) with an estimated uncertainty of 1.''3 combined statistical and systematic error. Moreover, both the X-ray to {gamma}-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray source has no cataloged infrared-to-visible counterpart and, through new observations, we set upper limits to its optical emission of i' > 23.0 mag and r' > 25.2 mag. The source exhibits an X-ray spectrum with most likely both a power law and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.

THE IDENTIFICATION OF THE X-RAY COUNTERPART TO PSR J2021+4026

International Nuclear Information System (INIS)

Weisskopf, Martin C.; Elsner, Ronald F.; O'Dell, Stephen L.; Tennant, Allyn F.; Romani, Roger W.; Razzano, Massimiliano; Belfiore, Andrea; Saz Parkinson, Pablo; Ziegler, Marcus; Dormody, Michael; Ray, Paul S.; Kerr, Matthew; Harding, Alice; Swartz, Douglas A.; Carramiñana, Alberto; Becker, Werner; Kanbach, Gottfried; De Luca, Andrea; Thompson, David J.

2011-01-01

We report the probable identification of the X-ray counterpart to the γ-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20 h 21 m 30. s 733, decl. +40°26'46.''04 (J2000) with an estimated uncertainty of 1.''3 combined statistical and systematic error. Moreover, both the X-ray to γ-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray source has no cataloged infrared-to-visible counterpart and, through new observations, we set upper limits to its optical emission of i' > 23.0 mag and r' > 25.2 mag. The source exhibits an X-ray spectrum with most likely both a power law and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.

Tachyonic cyclotron radiation

International Nuclear Information System (INIS)

Tomaschitz, R.

2006-01-01

We study superluminal cyclotron emission by electrons and muons in semiclassical orbits. The tachyonic line spectra of hydrogenic ions such as H, 56 Fe 25+ , and 238 U 91+ , as well as their muonic counterparts pμ - , 56 Fe 26+ μ - and 238 U 92+ μ - are calculated, in particular the tachyonic power transversally and longitudinally radiated, the total intensity, and the power radiated in the individual harmonics. We also investigate tachyonic continuum radiation from electrons and protons cycling in the surface and light cylinder fields of γ -ray and millisecond pulsars, such as the Crab pulsar, PSR B1509-58, and PSR J0218 + 4232. The superluminal spectral densities generated by non-relativistic, mildly relativistic and ultra-relativistic source particles are derived. We study the parameters determining the global shape of the transversal and longitudinal densities and the energy scales of the broadband spectrum. The observed cutoff frequency in the γ-ray band of the pulsars is used to infer the upper edge of the orbital energy, and we conclude that electrons and nuclei cycling in the surface fields can reach energies beyond the ''ankle'' of the cosmic ray spectrum. This suggests γ-ray pulsars as sources of ultra-high energy cosmic rays. (orig.)

Evolving ONe WD+He star systems to intermediate-mass binary pulsars

Science.gov (United States)

Liu, D.; Wang, B.; Chen, W.; Zuo, Z.; Han, Z.

2018-06-01

It has been suggested that accretion-induced collapse (AIC) is a non-negligible path for the formation of the observed neutron stars (NSs). An ONe white dwarf (WD) that accretes material from a He star may experience AIC process and eventually produce intermediate-mass binary pulsars (IMBPs), named as the ONe WD+He star scenario. Note that previous studies can only account for part of the observed IMBPs with short orbital periods. In this work, we investigate the evolution of about 900 ONe WD+He star binaries to explore the distribution of IMBPs. We found that the ONe WD+He star scenario could form IMBPs including pulsars with 5-340 ms spin periods and 0.75-1.38 M_{⊙} WD companions, in which the orbital periods range from 0.04 to 900 d. Compared with the 20 observed IMBPs, this scenario can cover the parameters of 13 sources in the final orbital period-WD mass plane and the Corbet diagram, most of which have short orbital periods. We found that the ONe WD+He star scenario can explain almost all the observed IMBPs with short orbital periods. This work can well match the observed parameters of PSR J1802-2124 (one of the two precisely observed IMBPs), providing a possible evolutional path for its formation. We also speculate that the compact companion of HD 49798 (a hydrogen depleted sdO6 star) may be not a NS based on this work.

Galactic population of pulsars

International Nuclear Information System (INIS)

Lyne, A.G.; Manchester, R.N.

1985-01-01

In order to draw statistical conclusions about the overall population of pulsars in the Galaxy, a sample of 316 pulsars detected in surveys carried out at Jodrell Bank, Arecibo, Molonglo, and Green Bank has been analysed. The important selection effects of each survey are quantified and a statistically reliable pulsar distance scale based on a model for the large-scale distribution of free electrons in the Galaxy is described. These results allow the spatial and luminosity distribution functions of galactic pulsars to be computed. It is concluded that the Galaxy contains approximately 70 000 potentially observable pulsars with luminosities above 0.3 mJy kpc 2 . The period and luminosity evolution of pulsars, is also considered. (author)

The Green Bank North Celestial Cap Pulsar Survey: New Pulsars and Future Prospects

Science.gov (United States)

Lynch, Ryan S.; Swiggum, Joe; Stovall, Kevin; Chawla, Pragya; DeCesar, Megan E.; Fonseca, Emmanuel; Levin, Lina; Cui, Bingyi; Kondratiev, Vlad; Archibald, Anne; Boyles, Jason; Hessels, Jason W. T.; Jenet, Fredrick; Kaplan, David; Karako-Argaman, Chen; Kaspi, Victoria; Martinez, Jose; McLaughlin, Maura; Ransom, Scott M.; Roberts, Mallory; Siemens, Xavier; Spiewak, Renee; Stairs, Ingrid; van Leeuwn, Joeri; Green Bank North Celestial Cap Survey Collaboration

2018-01-01

The Green Bank North Celestial Cap pulsar survey is the most successful low frequency pulsar survey ever. GBNCC uses the Green Bank telescope to cover the full visible sky at 350 MHz. With the survey over 70% complete, we have discovered over 150 pulsars, including 20 MSPs and 11 RRATs. I will report on the current status of the survey and plans for its completion in the coming years. I will also report on several discoveries including: timing solutions for dozens of new pulsars; new high precision MSPs and their suitability for inclusion in pulsar timing arrays; a new relativistic double neutron star system; new pulsar mass measurements; proper motion measurements for several MSPs; a new mode changing pulsar; interesting new MSP binaries; nulling fraction analyses; and possible implications of the lack of any fast radio bursts in the survey so far.

Discovery of a Highly Relativistic Double Neutron Star Binary

Science.gov (United States)

Chatterjee, Shami; Stovall, Kevin; PALFA Collaboration, Paul Demorest, Nihan Pol

2018-01-01

We report the discovery of a double neutron star (DNS) binary system, PSR J1946+2052, in Arecibo L-Band Feed Array Pulsar Survey (PALFA) observations. PSR J1946+2052 is a 17-ms pulsar in a 1.88-hour, eccentric (e = 0.06) orbit with a 1.2 solar mass companion. We have localized the pulsar to a precision of 0.09 arcseconds using a new phase binning mode at the Jansky Very Large Array. The improved position has enabled a measurement of the pulsar spin period derivative of 9E-19 s/s; the low inferred magnetic field strength at the surface of 4E+9 Gauss indicates that the pulsar has been recycled. Among all known DNS systems, PSR J1946+2052 has the shortest orbital period, and currently radiates ~13% of a solar luminosity in gravitational wave power. Its estimated time to merger is only 45.5 MYr, the shortest known, and at that time it will display the largest spin effects of any such system discovered to date. We have also measured the advance of periastron passage for this system, 25.6 +/- 0.3 degrees per year, resulting in a total system mass measurement of 2.50 +/- 0.04 solar masses.

Constraining Gamma-Ray Pulsar Gap Models with a Simulated Pulsar Population

Science.gov (United States)

Pierbattista, Marco; Grenier, I. A.; Harding, A. K.; Gonthier, P. L.

2012-01-01

With the large sample of young gamma-ray pulsars discovered by the Fermi Large Area Telescope (LAT), population synthesis has become a powerful tool for comparing their collective properties with model predictions. We synthesised a pulsar population based on a radio emission model and four gamma-ray gap models (Polar Cap, Slot Gap, Outer Gap, and One Pole Caustic). Applying gamma-ray and radio visibility criteria, we normalise the simulation to the number of detected radio pulsars by a select group of ten radio surveys. The luminosity and the wide beams from the outer gaps can easily account for the number of Fermi detections in 2 years of observations. The wide slot-gap beam requires an increase by a factor of 10 of the predicted luminosity to produce a reasonable number of gamma-ray pulsars. Such large increases in the luminosity may be accommodated by implementing offset polar caps. The narrow polar-cap beams contribute at most only a handful of LAT pulsars. Using standard distributions in birth location and pulsar spin-down power (E), we skew the initial magnetic field and period distributions in a an attempt to account for the high E Fermi pulsars. While we compromise the agreement between simulated and detected distributions of radio pulsars, the simulations fail to reproduce the LAT findings: all models under-predict the number of LAT pulsars with high E , and they cannot explain the high probability of detecting both the radio and gamma-ray beams at high E. The beaming factor remains close to 1.0 over 4 decades in E evolution for the slot gap whereas it significantly decreases with increasing age for the outer gaps. The evolution of the enhanced slot-gap luminosity with E is compatible with the large dispersion of gamma-ray luminosity seen in the LAT data. The stronger evolution predicted for the outer gap, which is linked to the polar cap heating by the return current, is apparently not supported by the LAT data. The LAT sample of gamma-ray pulsars

Status of the PSR improvement program

International Nuclear Information System (INIS)

Macek, R.J.; Fitzgerald, D.H.; Hoehn, M.V.; Ryder, R.D.; York, R.L.

1993-01-01

A program of improvements to increase intensity and improve reliability of the Los Alamos Proton Storage Ring (PSR) has been under way for several years. Reduction of stored beam loss rates by a factor of 4.6 since 1987 through exploitation of H 0 injection has allowed the average intensity to increase by a factor of two to 75μA. Reliability of the PSR and associated beam delivery systems has been improved by extensive rework of numerous subsystems. Radiation protection has been improved by additional shielding of Line D and extensive use of relatively fail-safe radiation detectors incorporated into an improved radiation security system

Two-component scattering model and the electron density spectrum

Science.gov (United States)

Zhou, A. Z.; Tan, J. Y.; Esamdin, A.; Wu, X. J.

2010-02-01

In this paper, we discuss a rigorous treatment of the refractive scintillation caused by a two-component interstellar scattering medium and a Kolmogorov form of density spectrum. It is assumed that the interstellar scattering medium is composed of a thin-screen interstellar medium (ISM) and an extended interstellar medium. We consider the case that the scattering of the thin screen concentrates in a thin layer represented by a δ function distribution and that the scattering density of the extended irregular medium satisfies the Gaussian distribution. We investigate and develop equations for the flux density structure function corresponding to this two-component ISM geometry in the scattering density distribution and compare our result with the observations. We conclude that the refractive scintillation caused by this two-component ISM scattering gives a more satisfactory explanation for the observed flux density variation than does the single extended medium model. The level of refractive scintillation is strongly sensitive to the distribution of scattering material along the line of sight (LOS). The theoretical modulation indices are comparatively less sensitive to the scattering strength of the thin-screen medium, but they critically depend on the distance from the observer to the thin screen. The logarithmic slope of the structure function is sensitive to the scattering strength of the thin-screen medium, but is relatively insensitive to the thin-screen location. Therefore, the proposed model can be applied to interpret the structure functions of flux density observed in pulsar PSR B2111 + 46 and PSR B0136 + 57. The result suggests that the medium consists of a discontinuous distribution of plasma turbulence embedded in the interstellar medium. Thus our work provides some insight into the distribution of the scattering along the LOS to the pulsar PSR B2111 + 46 and PSR B0136 + 57.

Increasing Pulsar Timing Array Sensitivity Through Addition of Millisecond Pulsars

Science.gov (United States)

DeCesar, Megan E.; Crawford, Fronefield; Ferrara, Elizabeth; Lynch, Ryan; Mingarelli, Chiara; Levin Preston, Lina; Ransom, Scott; Romano, Joseph; Simon, Joseph; Spiewak, Renee; Stovall, Kevin; Swiggum, Joe; Taylor, Stephen; Green Bank North Celestial Cap Pulsar Survey, Fermi LAT Collaboration, Fermi Pulsar Search Consortium

2018-01-01

Siemens et al. (2013) and Taylor et al. (2016) demonstrated the importance of increasing the number of millisecond pulsars (MSPs) in pulsar timing arrays (PTAs) in order to increase the sensitivity of the array and decrease the time-to-detection of a gravitational wave background (GWB). In particular, they predict that adding four MSPs per year to the NANOGrav and International PTAs will likely yield a GWB detection in less than a decade. A more even distribution of MSPs across the sky is also important for discriminating a GWB signal from a non-quadrupolar background (Sampson et al., in prep). Pulsar surveys and targeted searches have consistently led to additions of 4 or more MSPs per year to PTAs. I will describe these ongoing efforts, particularly in the context of the Green Bank North Celestial Cap pulsar survey and Fermi-guided searches at Green Bank and Arecibo that seek to find MSPs in low-pulsar-density regions of the sky.

Pulsar timing and its applications

OpenAIRE

Manchester, R N

2018-01-01

Pulsars are remarkably precise "celestial clocks" that can be used to explore many different aspects of physics and astrophysics. In this article I give a brief summary of pulsar properties and describe some of the applications of pulsar timing, including tests of theories of gravitation, efforts to detect low-frequency gravitational waves using pulsar timing arrays and establishment a "pulsar timescale".

Pulsar slow-down epochs

International Nuclear Information System (INIS)

Heintzmann, H.; Novello, M.

1981-01-01

The relative importance of magnetospheric currents and low frequency waves for pulsar braking is assessed and a model is developed which tries to account for the available pulsar timing data under the unifying aspect that all pulsars have equal masses and magnetic moments and are born as rapid rotators. Four epochs of slow-down are distinguished which are dominated by different braking mechanisms. According to the model no direct relationship exists between 'slow-down age' and true age of a pulsar and leads to a pulsar birth-rate of one event per hundred years. (Author) [pt

Binary and Millisecond Pulsars

Directory of Open Access Journals (Sweden)

Lorimer Duncan R.

2005-11-01

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 1700. There are now 80 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 103 pulsars in 24 of the Galactic globular clusters. Recent highlights have been the discovery of the first ever double pulsar system and a recent flurry of discoveries in globular clusters, in particular Terzan 5.

[Comparing the ranges of defect measured with standard white on white and Pulsar perimetries].

Science.gov (United States)

González de la Rosa, M; González-Hernández, M; García-Feijoo, J; Sánchez Méndez, M; García-Sánchez, J

2011-04-01

Normal thresholds on Pulsar perimetry fall faster than those of standard perimetry in the peripheral visual field. Two related studies were performed. Firstly, the frequency distributions of glaucoma defects on standard automated perimetry (SAP) and the relationship of the centre and periphery (Study A) were studied first, followed by an attempt to establish the limits of pulsar perimetry (Study B). A: frequency of defects was calculated in 78.663 SAP perimetries (G1-TOP, Octopus 1-2-3, Haag-Streit). Study B: 204 eyes with mean defect (MD-SAP) lower than 9 dB were examined 8.92 ± 4.19 times with SAP (TOP-32, Octopus 311) and temporal modulation perimetry (T30W, Pulsar Perimeter, Haag-Streit). Study A: 50.7% of the SAP examinations showed MD values lower than 9 dB and 32.7% bellow 6 dB. The MD correlation of the central 20° with the MD of the most peripheral points was r=0.933. Study B: in cases with MD-TOP-32 lower than 6 dB, SAP had the maximum possibility of detecting defect in 0.02% of points and Pulsar in 0.29%. In subjects with MD-TOP-32 between 6 and 9 dB frequencies were 0.38% in SAP and 3.5% in Pulsar (5.1% for eccentricities higher than 20°). Pulsar allows detecting defects, without range limitations, in the initial half of SAP frequencies expected on glaucoma patients. In order to study the progression of deeper defects the examination should focus on the central points, where the dynamic range of both systems is more equivalent. Copyright © 2010 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

Oldest pulsars in the Universe

International Nuclear Information System (INIS)

Shaham, J.

1987-01-01

Since the discovery of the Vulpecula pulsar two more superfast pulsars have been reported. In 1983 a 6.13-millisecond pulsar (called 1953 + 29) was announced, and in 1986 a 5.362-millisecond pulsar (called 1855 + 09) was publicized. A candidate for a fourth has been mentioned. As more evidence becomes available, it seems increasingly likely that the superfast pulsars can be explained only as a part of a new class of pulsars. Although many of the details of the class remain obscured, some general facts are emerging. Perhaps most interesting of all is the great age these new celestial objects are thought to have. Ordinary pulsars are relatively young, typically less than a million years old; the Crab pulsar, which is the youngest one known, is a mere infant of 932 years. The superfast pulsars, in comparison, are thought to be ancient. They are probably the result of evolutionary processes that could go back as much as a billion years, or one-twentieth of the age of the universe, and they are likely to live for several billion years more. 8 figures

Pulsars for the Beginner

Science.gov (United States)

DiLavore, Phillip; Wayland, James R.

1971-01-01

Presents the history of the discovery of pulsars, observations that have been made on pulsar radiation, and theories that have been presented for its presence and origin. Illustrations using pulsar's properties are presented in mechanics, electromagnetic radiation and thermodynamics. (DS)

Cosmic Ray Positrons from Pulsars

Science.gov (United States)

Harding, Alice K.

2010-01-01

Pulsars are potential Galactic sources of positrons through pair cascades in their magnetospheres. There are, however, many uncertainties in establishing their contribution to the local primary positron flux. Among these are the local density of pulsars, the cascade pair multiplicities that determine the injection rate of positrons from the pulsar, the acceleration of the injected particles by the pulsar wind termination shock, their rate of escape from the pulsar wind nebula, and their propagation through the interstellar medium. I will discuss these issues in the context of what we are learning from the new Fermi pulsar detections and discoveries.

THE QUASI-ROCHE LOBE OVERFLOW STATE IN THE EVOLUTION OF CLOSE BINARY SYSTEMS CONTAINING A RADIO PULSAR

Energy Technology Data Exchange (ETDEWEB)

Benvenuto, O. G.; De Vito, M. A. [Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata and Instituto de Astrofísica de La Plata (IALP), CCT-CONICET-UNLP. Paseo del Bosque S/N (B1900FWA), La Plata (Argentina); Horvath, J. E., E-mail: adevito@fcaglp.unlp.edu.ar, E-mail: foton@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)

2015-01-01

We study the evolution of close binary systems formed by a normal (solar composition), intermediate-mass-donor star together with a neutron star. We consider models including irradiation feedback and evaporation. These nonstandard ingredients deeply modify the mass-transfer stages of these binaries. While models that neglect irradiation feedback undergo continuous, long-standing mass-transfer episodes, models including these effects suffer a number of cycles of mass transfer and detachment. During mass transfer, the systems should reveal themselves as low-mass X-ray binaries (LMXBs), whereas when they are detached they behave as binary radio pulsars. We show that at these stages irradiated models are in a Roche lobe overflow (RLOF) state or in a quasi-RLOF state. Quasi-RLOF stars have radii slightly smaller than their Roche lobes. Remarkably, these conditions are attained for an orbital period as well as donor mass values in the range corresponding to a family of binary radio pulsars known as ''redbacks''. Thus, redback companions should be quasi-RLOF stars. We show that the characteristics of the redback system PSR J1723-2837 are accounted for by these models. In each mass-transfer cycle these systems should switch from LMXB to binary radio pulsar states with a timescale of approximately one million years. However, there is recent and fast growing evidence of systems switching on far shorter, human timescales. This should be related to instabilities in the accretion disk surrounding the neutron star and/or radio ejection, still to be included in the model having the quasi-RLOF state as a general condition.

Phylogenetic distribution and membrane topology of the LytR-CpsA-Psr protein family

Directory of Open Access Journals (Sweden)

Berger-Bächi Brigitte

2008-12-01

Full Text Available Abstract Background The bacterial cell wall is the target of many antibiotics and cell envelope constituents are critical to host-pathogen interactions. To combat resistance development and virulence, a detailed knowledge of the individual factors involved is essential. Members of the LytR-CpsA-Psr family of cell envelope-associated attenuators are relevant for β-lactam resistance, biofilm formation, and stress tolerance, and they are suggested to play a role in cell wall maintenance. However, their precise function is still unknown. This study addresses the occurrence as well as sequence-based characteristics of the LytR-CpsA-Psr proteins. Results A comprehensive list of LytR-CpsA-Psr proteins was established, and their phylogenetic distribution and clustering into subgroups was determined. LytR-CpsA-Psr proteins were present in all Gram-positive organisms, except for the cell wall-deficient Mollicutes and one strain of the Clostridiales. In contrast, the majority of Gram-negatives did not contain LytR-CpsA-Psr family members. Despite high sequence divergence, the LytR-CpsA-Psr domains of different subclusters shared a highly similar, predicted mixed a/β-structure, and conserved charged residues. PhoA fusion experiments, using MsrR of Staphylococcus aureus, confirmed membrane topology predictions and extracellular location of its LytR-CpsA-Psr domain. Conclusion The LytR-CpsA-Psr domain is unique to bacteria. The presence of diverse subgroups within the LytR-CpsA-Psr family might indicate functional differences, and could explain variations in phenotypes of respective mutants reported. The identified conserved structural elements and amino acids are likely to be important for the function of the domain and will help to guide future studies of the LytR-CpsA-Psr proteins.

Observational properties of pulsars.

Science.gov (United States)

Manchester, R N

2004-04-23

Pulsars are remarkable clocklike celestial sources that are believed to be rotating neutron stars formed in supernova explosions. They are valuable tools for investigations into topics such as neutron star interiors, globular cluster dynamics, the structure of the interstellar medium, and gravitational physics. Searches at radio and x-ray wavelengths over the past 5 years have resulted in a large increase in the number of known pulsars and the discovery of new populations of pulsars, posing challenges to theories of binary and stellar evolution. Recent images at radio, optical, and x-ray wavelengths have revealed structures resulting from the interaction of pulsar winds with the surrounding interstellar medium, giving new insights into the physics of pulsars.

The Velocity Distribution of Isolated Radio Pulsars

Science.gov (United States)

Arzoumanian, Z.; Chernoff, D. F.; Cordes, J. M.; White, Nicholas E. (Technical Monitor)

2002-01-01

We infer the velocity distribution of radio pulsars based on large-scale 0.4 GHz pulsar surveys. We do so by modelling evolution of the locations, velocities, spins, and radio luminosities of pulsars; calculating pulsed flux according to a beaming model and random orientation angles of spin and beam; applying selection effects of pulsar surveys; and comparing model distributions of measurable pulsar properties with survey data using a likelihood function. The surveys analyzed have well-defined characteristics and cover approx. 95% of the sky. We maximize the likelihood in a 6-dimensional space of observables P, dot-P, DM, absolute value of b, mu, F (period, period derivative, dispersion measure, Galactic latitude, proper motion, and flux density). The models we test are described by 12 parameters that characterize a population's birth rate, luminosity, shutoff of radio emission, birth locations, and birth velocities. We infer that the radio beam luminosity (i) is comparable to the energy flux of relativistic particles in models for spin-driven magnetospheres, signifying that radio emission losses reach nearly 100% for the oldest pulsars; and (ii) scales approximately as E(exp 1/2) which, in magnetosphere models, is proportional to the voltage drop available for acceleration of particles. We find that a two-component velocity distribution with characteristic velocities of 90 km/ s and 500 km/ s is greatly preferred to any one-component distribution; this preference is largely immune to variations in other population parameters, such as the luminosity or distance scale, or the assumed spin-down law. We explore some consequences of the preferred birth velocity distribution: (1) roughly 50% of pulsars in the solar neighborhood will escape the Galaxy, while approx. 15% have velocities greater than 1000 km/ s (2) observational bias against high velocity pulsars is relatively unimportant for surveys that reach high Galactic absolute value of z distances, but is severe for

Revival of the Magnetar PSR J1622–4950: Observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

Science.gov (United States)

Camilo, F.; Scholz, P.; Serylak, M.; Buchner, S.; Merryfield, M.; Kaspi, V. M.; Archibald, R. F.; Bailes, M.; Jameson, A.; van Straten, W.; Sarkissian, J.; Reynolds, J. E.; Johnston, S.; Hobbs, G.; Abbott, T. D.; Adam, R. M.; Adams, G. B.; Alberts, T.; Andreas, R.; Asad, K. M. B.; Baker, D. E.; Baloyi, T.; Bauermeister, E. F.; Baxana, T.; Bennett, T. G. H.; Bernardi, G.; Booisen, D.; Booth, R. S.; Botha, D. H.; Boyana, L.; Brederode, L. R. S.; Burger, J. P.; Cheetham, T.; Conradie, J.; Conradie, J. P.; Davidson, D. B.; De Bruin, G.; de Swardt, B.; de Villiers, C.; de Villiers, D. I. L.; de Villiers, M. S.; de Villiers, W.; De Waal, C.; Dikgale, M. A.; du Toit, G.; du Toit, L. J.; Esterhuyse, S. W. P.; Fanaroff, B.; Fataar, S.; Foley, A. R.; Foster, G.; Fourie, D.; Gamatham, R.; Gatsi, T.; Geschke, R.; Goedhart, S.; Grobler, T. L.; Gumede, S. C.; Hlakola, M. J.; Hokwana, A.; Hoorn, D. H.; Horn, D.; Horrell, J.; Hugo, B.; Isaacson, A.; Jacobs, O.; Jansen van Rensburg, J. P.; Jonas, J. L.; Jordaan, B.; Joubert, A.; Joubert, F.; Józsa, G. I. G.; Julie, R.; Julius, C. C.; Kapp, F.; Karastergiou, A.; Karels, F.; Kariseb, M.; Karuppusamy, R.; Kasper, V.; Knox-Davies, E. C.; Koch, D.; Kotzé, P. P. A.; Krebs, A.; Kriek, N.; Kriel, H.; Kusel, T.; Lamoor, S.; Lehmensiek, R.; Liebenberg, D.; Liebenberg, I.; Lord, R. T.; Lunsky, B.; Mabombo, N.; Macdonald, T.; Macfarlane, P.; Madisa, K.; Mafhungo, L.; Magnus, L. G.; Magozore, C.; Mahgoub, O.; Main, J. P. L.; Makhathini, S.; Malan, J. A.; Malgas, P.; Manley, J. R.; Manzini, M.; Marais, L.; Marais, N.; Marais, S. J.; Maree, M.; Martens, A.; Matshawule, S. D.; Matthysen, N.; Mauch, T.; McNally, L. D.; Merry, B.; Millenaar, R. P.; Mjikelo, C.; Mkhabela, N.; Mnyandu, N.; Moeng, I. T.; Mokone, O. J.; Monama, T. E.; Montshiwa, K.; Moss, V.; Mphego, M.; New, W.; Ngcebetsha, B.; Ngoasheng, K.; Niehaus, H.; Ntuli, P.; Nzama, A.; Obies, F.; Obrocka, M.; Ockards, M. T.; Olyn, C.; Oozeer, N.; Otto, A. J.; Padayachee, Y.; Passmoor, S.; Patel, A. A.; Paula, S.; Peens-Hough, A.; Pholoholo, B.; Prozesky, P.; Rakoma, S.; Ramaila, A. J. T.; Rammala, I.; Ramudzuli, Z. R.; Rasivhaga, M.; Ratcliffe, S.; Reader, H. C.; Renil, R.; Richter, L.; Robyntjies, A.; Rosekrans, D.; Rust, A.; Salie, S.; Sambu, N.; Schollar, C. T. G.; Schwardt, L.; Seranyane, S.; Sethosa, G.; Sharpe, C.; Siebrits, R.; Sirothia, S. K.; Slabber, M. J.; Smirnov, O.; Smith, S.; Sofeya, L.; Songqumase, N.; Spann, R.; Stappers, B.; Steyn, D.; Steyn, T. J.; Strong, R.; Struthers, A.; Stuart, C.; Sunnylall, P.; Swart, P. S.; Taljaard, B.; Tasse, C.; Taylor, G.; Theron, I. P.; Thondikulam, V.; Thorat, K.; Tiplady, A.; Toruvanda, O.; van Aardt, J.; van Balla, T.; van den Heever, L.; van der Byl, A.; van der Merwe, C.; van der Merwe, P.; van Niekerk, P. C.; van Rooyen, R.; van Staden, J. P.; van Tonder, V.; van Wyk, R.; Wait, I.; Walker, A. L.; Wallace, B.; Welz, M.; Williams, L. P.; Xaia, B.; Young, N.; Zitha, S.

2018-04-01

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622–4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100× larger than during its dormant state. The X-ray flux one month after reactivation was at least 800× larger than during quiescence, and has been decaying exponentially on a 111 ± 19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3–6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6–8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.

Pulsars as the sources of high energy cosmic ray positrons

International Nuclear Information System (INIS)

Hooper, Dan; Blasi, Pasquale; Serpico, Pasquale Dario

2009-01-01

Recent results from the PAMELA satellite indicate the presence of a large flux of positrons (relative to electrons) in the cosmic ray spectrum between approximately 10 and 100 GeV. As annihilating dark matter particles in many models are predicted to contribute to the cosmic ray positron spectrum in this energy range, a great deal of interest has resulted from this observation. Here, we consider pulsars (rapidly spinning, magnetized neutron stars) as an alternative source of this signal. After calculating the contribution to the cosmic ray positron and electron spectra from pulsars, we find that the spectrum observed by PAMELA could plausibly originate from such sources. In particular, a significant contribution is expected from the sum of all mature pulsars throughout the Milky Way, as well as from the most nearby mature pulsars (such as Geminga and B0656+14). The signal from nearby pulsars is expected to generate a small but significant dipole anisotropy in the cosmic ray electron spectrum, potentially providing a method by which the Fermi gamma-ray space telescope would be capable of discriminating between the pulsar and dark matter origins of the observed high energy positrons

Discovery of the Orbit of the X-ray pulsar OAO 1657-415

Science.gov (United States)

Chakrabarty, Deepto; Grunsfeld, John M.; Prince, Thomas A.; Bildsten, Lars; Finger, Mark H.; Wilson, Robert B.; Fishman, Gerald J.; Meegan, Charles A.; Paciesas, William S.

1993-01-01

Timing observations of the 38 s accreting X-ray pulsar OAO 1657-415 made with the BATSE large-area detectors on the Compton Gamma Ray Observatory have revealed a binary orbit with an X-ray eclipse by the stellar companion. From the pulsar mass function fx(M) = 11.7 +/- 0.2 solar masses and the measured eclipse half-angle theta(e) = 29.7 +/- 1.3 deg, we infer that the stellar companion is a supergiant of spectral class B0-B6. If the companion can be identified and its orbital velocity measured, the neutron star mass can be constrained. Both intrinsic spin-up and spin-down of the pulsar were measured during our observation.

Using HAWC to discover invisible pulsars

Energy Technology Data Exchange (ETDEWEB)

Linden, Tim; Auchettl, Katie; Bramante, Joseph; Cholis, Ilias; Fang, Ke; Hooper, Dan; Karwal, Tanvi; Li, Shirley Weishi

2017-11-01

Observations by HAWC and Milagro have detected bright and spatially extended TeV gamma-ray sources surrounding the Geminga and Monogem pulsars. We argue that these observations, along with a substantial population of other extended TeV sources coincident with pulsar wind nebulae, constitute a new morphological class of spatially extended TeV halos. We show that HAWCs wide field-of-view unlocks an expansive parameter space of TeV halos not observable by atmospheric Cherenkov telescopes. Under the assumption that Geminga and Monogem are typical middle-aged pulsars, we show that ten-year HAWC observations should eventually observe 37$^{+17}_{-13}$ middle-aged TeV halos that correspond to pulsars whose radio emission is not beamed towards Earth. Depending on the extrapolation of the TeV halo efficiency to young pulsars, HAWC could detect more than 100 TeV halos from mis-aligned pulsars. These pulsars have historically been difficult to detect with existing multiwavelength observations. TeV halos will constitute a significant fraction of all HAWC sources, allowing follow-up observations to efficiently find pulsar wind nebulae and thermal pulsar emission. The observation and subsequent multi-wavelength follow-up of TeV halos will have significant implications for our understanding of pulsar beam geometries, the evolution of PWN, the diffusion of cosmic-rays near energetic pulsars, and the contribution of pulsars to the cosmic-ray positron excess.

TeV Gamma Rays From Galactic Center Pulsars

Energy Technology Data Exchange (ETDEWEB)

Hooper, Dan [Fermilab; Cholis, Ilias [Johns Hopkins U.; Linden, Tim [Ohio State U., CCAPP

2017-05-25

Measurements of the nearby pulsars Geminga and B0656+14 by the HAWC and Milagro telescopes have revealed the presence of bright TeV-emitting halos surrounding these objects. If young and middle-aged pulsars near the Galactic Center transfer a similar fraction of their energy into TeV photons, then these sources could dominate the emission that is observed by HESS and other ground-based telescopes from the innermost ~10^2 parsecs of the Milky Way. In particular, both the spectral shape and the angular extent of this emission is consistent with TeV halos produced by a population of pulsars. The overall flux of this emission requires a birth rate of ~100-1000 neutron stars per Myr near the Galactic Center, in good agreement with recent estimates.

The galactic distribution of pulsars

International Nuclear Information System (INIS)

Lyne, A.G.

1982-01-01

The galactic distribution of pulsars follows the general form of many population I objects in galactocentric radius, but has a wide distribution above and below the plane due to high space velocities imparted to the pulsars at birth. Statistical studies of the properties of large numbers of pulsars and proper motion measurements demonstrate that the effective magnetic dipole moments decay on a timescale of about 8 million years. This work provides a better knowledge of pulsar evolution and ages and shows that a birthrate of one pulsar every 20 to 50 years is required to sustain the observed galactic population of 300,000. This rate is comparable with most recent estimates of the galactic supernova rate, but requires nearly all supernovae to produce active pulsars. (orig.)

Pulsar magnetosphere-wind or wave

International Nuclear Information System (INIS)

Kennel, C.F.

1979-01-01

The structure of both the interior and exterior pulsar magnetosphere depends upon the strength of its plasma source near the surface of the star. We review wave models of exterior pulsar magnetospheres in the light of a vacuum pair-production source model proposed by Sturrock, and Ruderman and Sutherland. This model predicts the existence of a cutoff, determined by the neutron star's spin rate and magnetic field strenght, beyond which coherent radio emission is no longer possible. Since the observed distribution of pulsar spin periods and period derivatives, and the distribution of pulsars with missing radio pulses, is consistent with the pair production threshold, those neutron stars observed as radio pulsars can have relativistic magnetohydrodynamic wind exterior magnetospheres, and cannot have relativistic plasma wave exterior magnetospheres. On the other hand, most erstwhile pulsars in the galaxy are probably halo objects that emit weak fluxes of energetic photons that can have relativistic wave exterior magnetospheres. Extinct pulsars have not been yet observed

Study on the correlation of PSR with extended operation of NPP

International Nuclear Information System (INIS)

Shin, T. M.; Kim, H. K.; Cho, J. C.; Kim, H. J.

2002-01-01

For developed countries, which had already experienced the end of nuclear plant design life, it has been a trend to allow extended operation of plant in case that safety during the period of extended operation is ensured through safety assessment. Periodic Safety Review and License Renewal are the widely used system for safety assessment of extended operation. The PSR has been already adopted in our country and actively carried out one by one for each operating plant by the owner and its committed technical experts. In the paper, the interfaces between PSR and extended operation are reviewed in the regulatory viewpoint in recognition that various safety reviews are performed in PSR for the safety confirmation and enhancement, and that PSR can be effectively utilized for the review of extended operation. However, this study has been performed only on the research purpose and thus the final decision is up to the policy of government

ASSESSING THE ROLE OF SPIN NOISE IN THE PRECISION TIMING OF MILLISECOND PULSARS

International Nuclear Information System (INIS)

Shannon, Ryan M.; Cordes, James M.

2010-01-01

We investigate rotational spin noise (referred to as timing noise) in non-accreting pulsars: millisecond pulsars, canonical pulsars, and magnetars. Particular attention is placed on quantifying the strength and non-stationarity of timing noise in millisecond pulsars because the long-term stability of these objects is required to detect nanohertz gravitational radiation. We show that a single scaling law is sufficient to characterize timing noise in millisecond and canonical pulsars while the same scaling law underestimates the levels of timing noise in magnetars. The scaling law, along with a detailed study of the millisecond pulsar B1937+21, leads us to conclude that timing noise is latent in most millisecond pulsars and will be measurable in many objects when better arrival time estimates are obtained over long data spans. The sensitivity of a pulsar timing array to gravitational radiation is strongly affected by any timing noise. We conclude that detection of proposed gravitational wave backgrounds will require the analysis of more objects than previously suggested over data spans that depend on the spectra of both the gravitational wave background and of the timing noise. It is imperative to find additional millisecond pulsars in current and future surveys in order to reduce the effects of timing noise.

WHY ARE PULSAR PLANETS RARE?

Energy Technology Data Exchange (ETDEWEB)

Martin, Rebecca G.; Livio, Mario; Palaniswamy, Divya [Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, NV 89154 (United States)

2016-12-01

Pulsar timing observations have revealed planets around only a few pulsars. We suggest that the rarity of these planets is due mainly to two effects. First, we show that the most likely formation mechanism requires the destruction of a companion star. Only pulsars with a suitable companion (with an extreme mass ratio) are able to form planets. Second, while a dead zone (a region of low turbulence) in the disk is generally thought to be essential for planet formation, it is most probably rare in disks around pulsars, because of the irradiation from the pulsar. The irradiation strongly heats the inner parts of the disk, thus pushing the inner boundary of the dead zone out. We suggest that the rarity of pulsar planets can be explained by the low probability for these two requirements to be satisfied: a very low-mass companion and a dead zone.

Millisecond radio pulsars in globular clusters

Science.gov (United States)

Verbunt, Frank; Lewin, Walter H. G.; Van Paradijs, Jan

1989-01-01

It is shown that the number of millisecond radio pulsars, in globular clusters, should be larger than 100, applying the standard scenario that all the pulsars descend from low-mass X-ray binaries. Moreover, most of the pulsars are located in a small number of clusters. The prediction that Teran 5 and Liller 1 contain at least about a dozen millisecond radio pulsars each is made. The observations of millisecond radio pulsars in globular clusters to date, in particular the discovery of two millisecond radio pulsars in 47 Tuc, are in agreement with the standard scenario, in which the neutron star is spun up during the mass transfer phase.

40 Years of Pulsars: The Birth and Evolution of Isolated Radio Pulsars

OpenAIRE

Faucher-Giguere, C. -A.; Kaspi, V. M.

2007-01-01

We investigate the birth and evolution of isolated radio pulsars using a population synthesis method, modeling the birth properties of the pulsars, their time evolution, and their detection in the Parkes and Swinburne Multibeam (MB) surveys. Together, the Parkes and Swinburne MB surveys have detected nearly 2/3 of the known pulsars and provide a remarkably homogeneous sample to compare with simulations. New proper motion measurements and an improved model of the distribution of free electrons...

The Parkes multibeam pulsar survey and the discovery of new energetic radio pulsars

International Nuclear Information System (INIS)

D'Amico, N.; Possenti, A.; Kaspi, V.M.; Manchester, R.N.; Bell, J.F.; Camilo, F.; Lyne, A.G.; Kramer, M.; Hobbs, G.; Stairs, I.H.

2001-01-01

The Parkes multibeam pulsar survey is a deep search of the Galactic plane for pulsars. It uses a 13-beam receiver system operating at 1.4 GHz on the 64-m Parkes radio telescope. It has much higher sensitivity than any previous similar survey and is finding large numbers of previously unknown pulsars, many of which are relatively young and energetic. On the basis of an empirical comparison of their properties with other young radio pulsars, some of the new discoveries are expected to be observable as pulsed γ-ray sources. We describe the survey motivation, the experiment characteristics and the results achieved so far

The LOFAR Known Pulsar Data Pipeline

NARCIS (Netherlands)

Alexov, A.; Hessels, J.W.T.; Mol, J.D.; Stappers, B.; van Leeuwen, J.

2010-01-01

Abstract: Transient radio phenomena and pulsars are one of six LOFAR Key Science Projects (KSPs). As part of the Transients KSP, the Pulsar Working Group (PWG) has been developing the LOFAR Pulsar Data Pipelines to both study known pulsars as well as search for new ones. The pipelines are being

Visualization of Pulsar Search Data

Science.gov (United States)

Foster, R. S.; Wolszczan, A.

1993-05-01

The search for periodic signals from rotating neutron stars or pulsars has been a computationally taxing problem to astronomers for more than twenty-five years. Over this time interval, increases in computational capability have allowed ever more sensitive searches, covering a larger parameter space. The volume of input data and the general presence of radio frequency interference typically produce numerous spurious signals. Visualization of the search output and enhanced real-time processing of significant candidate events allow the pulsar searcher to optimally processes and search for new radio pulsars. The pulsar search algorithm and visualization system presented in this paper currently runs on serial RISC based workstations, a traditional vector based super computer, and a massively parallel computer. A description of the serial software algorithm and its modifications for massively parallel computing are describe. The results of four successive searches for millisecond period radio pulsars using the Arecibo telescope at 430 MHz have resulted in the successful detection of new long-period and millisecond period radio pulsars.

Pulsar observations with the MAGIC telescopes

Energy Technology Data Exchange (ETDEWEB)

Garcia, Jezabel R.; Dazzi, F.; Idec, W.; Moretti, E.; Schweizer, T. [Max-Planck-Institut fuer Physik, Munich (Germany); Bonnefoy, S.; Carreto-Fidalgo, D.; Lopez, M. [Universitad Compultense, Madrid (Spain); Galindo, D.; Zanin, R. [Universitat de Barcelona, ICC/IEEC-UB, Barcelona (Spain); Ona Wilhelmi, E. de [Institute for Space Sciences (CSIC/IEEC), Barcelona (Spain); Reichardt, I. [Istituto Nazionale di Fisica Nucleare (INFN), Padova (Italy); Saito, T. [Kyoto University, Hakubi Center (Japan); Collaboration: MAGIC-Collaboration

2016-07-01

MAGIC is a stereoscopic system of two IACTs, located at the ORM (Spain). Since 2008, MAGIC has played a big role in Pulsar physics due to the discovery of the first VHE gamma-ray emission from the Crab pulsar. Such a discovery was possible thanks to a revolutionary trigger technique used in the initial MAGIC mono system, the Sum-Trigger, that provided a 25 GeV energy threshold. The study of the Crab keeps providing numerous important results for the understanding of pulsar physics. The most recent ones are the bridge emission at VHE and the detection of the Crab pulsations at TeV energies. MAGIC has been also searching for new pulsars, providing recently interesting results about the Geminga pulsar and nebula. This talk reviews the essential MAGIC results about VHE pulsars and their implications for pulsar physics.Also we discuss the development of a new stereo trigger system, the Sum-Trigger-II, and the importance of the observation windows that this system opens for the study of VHE pulsars.

Global Current Circuit Structure in a Resistive Pulsar Magnetosphere Model

Science.gov (United States)

Kato, Yugo. E.

2017-12-01

Pulsar magnetospheres have strong magnetic fields and large amounts of plasma. The structures of these magnetospheres are studied using force-free electrodynamics. To understand pulsar magnetospheres, discussions must include their outer region. However, force-free electrodynamics is limited in it does not handle dissipation. Therefore, a resistive pulsar magnetic field model is needed. To break the ideal magnetohydrodynamic (MHD) condition E\\cdot B=0, Ohm’s law is used. This work introduces resistivity depending upon the distance from the star and obtain a self-consistent steady state by time integration. Poloidal current circuits form in the magnetosphere while the toroidal magnetic field region expands beyond the light cylinder and the Poynting flux radiation appears. High electric resistivity causes a large space scale poloidal current circuit and the magnetosphere radiates a larger Poynting flux than the linear increase outside of the light cylinder radius. The formed poloidal-current circuit has width, which grows with the electric conductivity. This result contributes to a more concrete dissipative pulsar magnetosphere model.

Research on the maximum utilization of PSR (Periodic Safety Review) results

Energy Technology Data Exchange (ETDEWEB)

Shin, Tae Myung; Lee, Jae Kyung; Ahn, Jin Chul; Kim, G. U.; Ryu, Y. S.; Lee, G. B.; Park, D. H. [Chungju Univ., Cheongju (Korea, Republic of)

2002-03-15

This is the final report of 'research on the maximum utilization of PSR results' focused on linkage strategy of PSR with continued operation over design life of operating NPP. Study was mace mainly on the analysis of current status of continued operation over plant design life in foreign countries, analysis of domestic PSR implementation status and establishment of basic strategy for linking PSR with continued operation. The results of the study performed so far can be summarized as below, the recent worldwide trend of promoting efficiency of NPP operation is focused on life extension of the plants rather than building of new. Considering the fact that some developed countries have already implemented the plant life extension and not a few countries at least have invested a good amount of fund for R and D of plant life management, we can not disregard the owner's request for review of life extension application without any reasonable description. As a result of investigation and analysis for the current status of continued operation over plant design life in foreign countries, it is concluded that most countries tend to link PSR with continued operation over plant design life and the extended operation has already been implemented in some developed countries. From the point, it turned out to be more desirable to couple those two systems for continued operation over plant design life of Korean NPP. A less than 7 years left until the end of design life for the oldest NPP Kori unit 1, it is strongly recommended to establish institutional frame including a legal basis and regulatory guidelines for continued operation over plant design life before long. For the prioritization methods of corrective actions in consideration of safety significance of shortcomings picked up from PSR, some related systems are reviewed including IAEA guidelines, PSR implementation experience of UK and US prioritization system for GSI (Generic Safety Issue). Basic principles are

Integral luminosities of radio pulsars

Science.gov (United States)

Malov, I.; Malov, O.

The integral radio luminosities L for 311 normal pulsars and for 27 ones with the rotation period Pfalls for fast ones. The mean values of K are -3.73 and -4.85 for normal and fast pulsars, respectively. There are no changes of L with the kinematic age T = z/V, where z is the pulsar height over the Galactic plane and V = 300 km/s is its mean velocity. The correlation between L and the rate of the rotation energy losses E is detected for both pulsar groups under consideration. It is shown that L= A E^(1/3) for the whole sample. The total number of pulsars in the Galaxy and their birth rate are in agreement with data on the rate of supernova explosions.

Sensitivity of Pulsar Timing Arrays

Science.gov (United States)

Siemens, Xavier

2015-08-01

For the better part of the last decade, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has been using the Green Bank and Arecibo radio telescopes to monitor millisecond pulsars. NANOGrav, along with similar international collaborations, the European Pulsar Timing Array and the Parkes Pulsar Timing Array in Australia, form a consortium of consortia: the International Pulsar Timing Array (IPTA). The goal of the IPTA is to directly detect low-frequency gravitational waves which cause small changes to the times of arrival of radio pulses from millisecond pulsars. In this talk I will discuss the work of NANOGrav and the IPTA as well as our sensitivity to gravitational waves from astrophysical sources. I will show that a detection is possible by the end of the decade.

Pulsar timing and general relativity

Science.gov (United States)

Backer, D. C.; Hellings, R. W.

1986-01-01

Techniques are described for accounting for relativistic effects in the analysis of pulsar signals. Design features of instrumentation used to achieve millisecond accuracy in the signal measurements are discussed. The accuracy of the data permits modeling the pulsar physical characteristics from the natural glitches in the emissions. Relativistic corrections are defined for adjusting for differences between the pulsar motion in its spacetime coordinate system relative to the terrestrial coordinate system, the earth's motion, and the gravitational potentials of solar system bodies. Modifications of the model to allow for a binary pulsar system are outlined, including treatment of the system as a point mass. Finally, a quadrupole model is presented for gravitational radiation and techniques are defined for using pulsars in the search for gravitational waves.

HAWC Observations Strongly Favor Pulsar Interpretations of the Cosmic-Ray Positron Excess

Energy Technology Data Exchange (ETDEWEB)

Hooper, Dan [Fermilab; Cholis, Ilias [Johns Hopkins U.; Linden, Tim [Ohio State U., CCAPP; Fang, Ke [Maryland U.

2017-11-17

Recent measurements of the Geminga and B0656+14 pulsars by the gamma-ray telescope HAWC (along with earlier measurements by Milagro) indicate that these objects generate significant fluxes of very high-energy electrons. In this paper, we use the very high-energy gamma-ray intensity and spectrum of these pulsars to calculate and constrain their expected contributions to the local cosmic-ray positron spectrum. Among models that are capable of reproducing the observed characteristics of the gamma-ray emission, we find that pulsars invariably produce a flux of high-energy positrons that is similar in spectrum and magnitude to the positron fraction measured by PAMELA and AMS-02. In light of this result, we conclude that it is very likely that pulsars provide the dominant contribution to the long perplexing cosmic-ray positron excess.

Radio spectra of pulsars. Pt. 1

International Nuclear Information System (INIS)

Izekova, V.A.; Kuzmin, A.D.; Malofeev, V.M.; Shitov, Yu.P.

1981-01-01

The results of flux pulsar radioemission measurements at meter wavelength, made at Pushchino Radio Astronomical Observatory of the Lebedev Physical Institute, are presented. Flux densities at 102, 85, 61 and 39 MHz have been measured for 85, 29, 37 and 23 pulsars correspondingly. Some of them were performed at all frequencies simultaneously. On the basis of these data and high frequencies data obtained by other authors, spectra of 52 pulsars were plotted. In practically all investigated pulsars we have detected a turn-over frequency at which the flux density of pulsar radioemission attained its maximum. Its mean value is vsub(m) = 130 +- 80 MHz. Averaged on many pulsars, the spectral index is negative in the 39-61 MHz frequency range (anti ALPHA 39 sub(-) 61 = -1.4 +- 0.4) and passes through zero at frequencies of about 100 MHz, becoming positive in the 100-400 MHz frequency range. It was noticed that the spectral index in the 100-400 MHz interval depends upon such pulsar periods as α 100 sub(-) 400 = 0.7 log p + 0.9. Using the spectra, more precise radio luminosities of pulsars have been computed. (orig.)

Rotation and Accretion Powered Pulsars

Energy Technology Data Exchange (ETDEWEB)

Kaspi, V M [Department of Physics, McGill University, 3600 University St, Montreal, QC H3A 2T8 (Canada)

2008-03-07

Pulsar astrophysics has come a long way in the 40 years since the discovery of the first pulsar by Bell and Hewish. From humble beginnings as bits of 'scruff' on the Cambridge University group's chart recorder paper, the field of pulsars has blossomed into a major area of mainstream astrophysics, with an unparalleled diversity of astrophysical applications. These range from Nobel-celebrated testing of general relativity in the strong-field regime to constraining the equation-of-state of ultradense matter; from probing the winds of massive stars to globular cluster evolution. Previous notable books on the subject of pulsars have tended to focus on some particular topic in the field. The classic text Pulsars by Manchester and Taylor (1977 San Francisco, CA: Freeman) targeted almost exclusively rotation-powered radio pulsars, while the Meszaros book High-Energy Radiation from Magnetized Neutron Stars (1992 Chicago, IL: University of Chicago Press) considered both rotation- and accretion-powered neutron stars, but focused on their radiation at x-ray energies and above. The recent book Neutron Stars 1 by Haensel et al (2007 Berlin: Springer) considers only the equation of state and neutron-star structure. Into this context appears Rotation and Accretion Powered Pulsars, by Pranab Ghosh. In contrast to other books, here the author takes an encyclopedic approach and attempts to synthesize practically all of the major aspects of the two main types of neutron star. This is ambitious. The only comparable undertaking is the useful but more elementary Lyne and Graham-Smith text Pulsar Astronomy (1998 Cambridge: Cambridge University Press), or Compact Stellar X-ray Sources (eds Lewin and van der Klis, 2006 Cambridge: Cambridge University Press), an anthology of technical review articles that also includes black hole topics. Rotation and Accretion Powered Pulsars thus fills a clear void in the field, providing a readable, graduate-level book that covers nearly

Rotation and Accretion Powered Pulsars

International Nuclear Information System (INIS)

Kaspi, V M

2008-01-01

Pulsar astrophysics has come a long way in the 40 years since the discovery of the first pulsar by Bell and Hewish. From humble beginnings as bits of 'scruff' on the Cambridge University group's chart recorder paper, the field of pulsars has blossomed into a major area of mainstream astrophysics, with an unparalleled diversity of astrophysical applications. These range from Nobel-celebrated testing of general relativity in the strong-field regime to constraining the equation-of-state of ultradense matter; from probing the winds of massive stars to globular cluster evolution. Previous notable books on the subject of pulsars have tended to focus on some particular topic in the field. The classic text Pulsars by Manchester and Taylor (1977 San Francisco, CA: Freeman) targeted almost exclusively rotation-powered radio pulsars, while the Meszaros book High-Energy Radiation from Magnetized Neutron Stars (1992 Chicago, IL: University of Chicago Press) considered both rotation- and accretion-powered neutron stars, but focused on their radiation at x-ray energies and above. The recent book Neutron Stars 1 by Haensel et al (2007 Berlin: Springer) considers only the equation of state and neutron-star structure. Into this context appears Rotation and Accretion Powered Pulsars, by Pranab Ghosh. In contrast to other books, here the author takes an encyclopedic approach and attempts to synthesize practically all of the major aspects of the two main types of neutron star. This is ambitious. The only comparable undertaking is the useful but more elementary Lyne and Graham-Smith text Pulsar Astronomy (1998 Cambridge: Cambridge University Press), or Compact Stellar X-ray Sources (eds Lewin and van der Klis, 2006 Cambridge: Cambridge University Press), an anthology of technical review articles that also includes black hole topics. Rotation and Accretion Powered Pulsars thus fills a clear void in the field, providing a readable, graduate-level book that covers nearly everything you

PSR1987A: the case for strange-quark stars

International Nuclear Information System (INIS)

Glendenning, N.K.

1989-01-01

The new fast pulsar observed in the remnant of SN1987A, together with other considerations, provide evidence that there are two types of collapsed stars: neutron stars, having moderate central densities and subject to the usual mass constraint, and strange-quark-matter stars. We show that (i) all known pulsar masses and frequencies, with the exception of the new one, can be accounted for by plausible neutron star models; (ii) no known neutron star model can withstand the fast rotation of the new pulsar unless the central energy density is ∼ 15 that of normal nuclei, at which densities hadrons cannot plausibly exist as constituents; and (iii) if strange-quark matter is the true ground state of the strong interactions, strange-quark stars can sustain the high rotation imputed to the new pulsar. In the absence of another plausible structure that can withstand the fast rotation, we provisionally infer that the new pulsar is such a star. (author)

Galactic distribution and evolution of pulsars

International Nuclear Information System (INIS)

Taylor, J.H.; Manchester, R.N.

1977-01-01

The distribution of pulsars with respect to period, z-distance, luminosity, and galactocentric radius has been investigated using data from three extensive pulsar surveys. It is shown that selection effects only slightly modify the observed period and z-distributions but strongly affect the observed luminosity function and galactic distribution. These latter two distributions are computed from the Jodrell Bank and Arecibo data, using an iterative procedure. The largest uncertainties in our results are the result of uncertainty in the adopted distance scale. Therefore, where relevant, separate calculations have been made for two values of the average interstellar electron density, , 0.02 cm -3 and 0.03 cm -3 .The derived luminosity function is closely represented by a power law with index (for logarithmic luminosity intervals) close to -1. For =0.03 cm -3 , the density of potentially observable pulsars is about 90 kpc -2 in the local region and increases with decreasing galactocentric radius. These distributions imply that the total number of pulsars in the Galaxy is about 10 5 . If only a fraction of all pulsars are observable because of beaming effects, then the total number in the Galaxy is correspondingly greater.Recent observations of pulsar proper motions show that pulsars are generally high-velocity objects. The observed z-distribution of pulsars implies that the mean age of observable pulsars does not exceed 2 x 10 6 years. With this mean age the pulsar birthrate required to maintain the observed galactic distribution is 10 -4 yr -1 kpc -2 in the local region and one pulsar birth every 6 years in the Galaxy as a whole. For =0.02 cm -3 , the corresponding rate is one birth every 40 years. These rates exceed most estimates of supernova occurrence rates and may require that all stars with mass greater than approx.2.5 Msun form pulsars at the end of their evolutionary life

Proposed new test of spin effects in general relativity.

Science.gov (United States)

O'Connell, R F

2004-08-20

The recent discovery of a double-pulsar PSR J0737-3039A/B provides an opportunity of unequivocally observing, for the first time, spin effects in general relativity. Existing efforts involve detection of the precession of the spinning body itself. However, for a close binary system, spin effects on the orbit may also be discernible. Not only do they add to the advance of the periastron (by an amount which is small compared to the conventional contribution) but they also give rise to a precession of the orbit about the spin direction. The measurement of such an effect would also give information on the moment of inertia of pulsars.

SIGPROC: Pulsar Signal Processing Programs

Science.gov (United States)

Lorimer, D. R.

2011-07-01

SIGPROC is a package designed to standardize the initial analysis of the many types of fast-sampled pulsar data. Currently recognized machines are the Wide Band Arecibo Pulsar Processor (WAPP), the Penn State Pulsar Machine (PSPM), the Arecibo Observatory Fourier Transform Machine (AOFTM), the Berkeley Pulsar Processors (BPP), the Parkes/Jodrell 1-bit filterbanks (SCAMP) and the filterbank at the Ooty radio telescope (OOTY). The SIGPROC tools should help users look at their data quickly, without the need to write (yet) another routine to read data or worry about big/little endian compatibility (byte swapping is handled automatically).

Pulsar Timing with the Fermi LAT

Science.gov (United States)

2010-12-01

Pulsar Timing with the Fermi LAT Paul S. Ray∗, Matthew Kerr†, Damien Parent∗∗ and the Fermi PSC‡ ∗Naval Research Laboratory, 4555 Overlook Ave., SW...Laboratory, Washington, DC 20375, USA ‡Fermi Pulsar Search Consortium Abstract. We present an overview of precise pulsar timing using data from the Large...unbinned photon data. In addition to determining the spindown behavior of the pulsars and detecting glitches and timing noise, such timing analyses al

Searching for pulsars using image pattern recognition

Energy Technology Data Exchange (ETDEWEB)

Zhu, W. W.; Berndsen, A.; Madsen, E. C.; Tan, M.; Stairs, I. H. [Department of Physics and Astronomy, 6224 Agricultural Road, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Brazier, A. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Lazarus, P. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Lynch, R.; Scholz, P. [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Stovall, K.; Cohen, S.; Dartez, L. P.; Lunsford, G.; Martinez, J. G.; Mata, A. [Center for Advanced Radio Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States); Ransom, S. M. [NRAO, Charlottesville, VA 22903 (United States); Banaszak, S.; Biwer, C. M.; Flanigan, J.; Rohr, M., E-mail: zhuww@phas.ubc.ca, E-mail: berndsen@phas.ubc.ca [Center for Gravitation, Cosmology and Astrophysics. University of Wisconsin Milwaukee, Milwaukee, WI 53211 (United States); and others

2014-02-01

In the modern era of big data, many fields of astronomy are generating huge volumes of data, the analysis of which can sometimes be the limiting factor in research. Fortunately, computer scientists have developed powerful data-mining techniques that can be applied to various fields. In this paper, we present a novel artificial intelligence (AI) program that identifies pulsars from recent surveys by using image pattern recognition with deep neural nets—the PICS (Pulsar Image-based Classification System) AI. The AI mimics human experts and distinguishes pulsars from noise and interference by looking for patterns from candidate plots. Different from other pulsar selection programs that search for expected patterns, the PICS AI is taught the salient features of different pulsars from a set of human-labeled candidates through machine learning. The training candidates are collected from the Pulsar Arecibo L-band Feed Array (PALFA) survey. The information from each pulsar candidate is synthesized in four diagnostic plots, which consist of image data with up to thousands of pixels. The AI takes these data from each candidate as its input and uses thousands of such candidates to train its ∼9000 neurons. The deep neural networks in this AI system grant it superior ability to recognize various types of pulsars as well as their harmonic signals. The trained AI's performance has been validated with a large set of candidates from a different pulsar survey, the Green Bank North Celestial Cap survey. In this completely independent test, the PICS ranked 264 out of 277 pulsar-related candidates, including all 56 previously known pulsars and 208 of their harmonics, in the top 961 (1%) of 90,008 test candidates, missing only 13 harmonics. The first non-pulsar candidate appears at rank 187, following 45 pulsars and 141 harmonics. In other words, 100% of the pulsars were ranked in the top 1% of all candidates, while 80% were ranked higher than any noise or interference. The