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Sample records for binary 4u 1822-371

  1. The Structure of the Accretion Disk in the ADC X-Ray Binary 4U 1822-371 at Optical and Ultraviolet Wavelengths

    CERN Document Server

    Bayless, Amanda J; Hynes, Robert I; Ashcraft, Teresa A; Cornell, Mark E

    2009-01-01

    The eclipsing low-mass X-ray binary 4U 1822-371 is the prototypical accretion disk corona (ADC) system. We have obtained new time-resolved UV spectroscopy of 4U 1822-371 with the Advanced Camera for Surveys/Solar Blind Channel (ACS/SBC) on the Hubble Space Telescope (HST) and new V- and J-band photometry with the 1.3-m SMARTS telescope at CTIO. We use the new data to construct its UV/optical spectral energy distribution and its orbital light curve in the UV, V, and J bands. We derive an improved ephemeris for the optical eclipses and confirm that the orbital period is changing rapidly, indicating extremely high rates of mass flow in the system; and we show that the accretion disk in the system has a strong wind with projected velocities up to 4000 km/s. We show that the disk has a vertically-extended, optically-thick component at optical wavelengths.This component extends almost to the edge of the disk and has a height equal to ~0.5 of the disk radius. As it has a low brightness temperature, we identify it as...

  2. Implications of X-Ray Line Variations for 4U1822-371

    CERN Document Server

    Ji, Li; Nowak, Michael A; Canizares, Claude R

    2010-01-01

    4U 1822-371 is one of the proto-type accretion disk coronal sources with an orbital period of about 5.6 hours. The binary is viewed almost edge-on at a high inclination angle of 83 degrees, which makes it a unique candidate to study binary orbital and accretion disk dynamics in high powered X-ray sources. We observed the X-ray source in 4U 1822-371 with the Chandra High Energy Transmission Grating Spectrometer (HETGS) for almost nine binary orbits. X-ray eclipse times provide an update of the orbital ephemeris. We find that our result follows the quadratic function implied by previous observations; however, it suggests a flatter trend. Detailed line dynamics also confirm a previous suggestion that the observed photo-ionized line emission originates from a confined region in the outer edge of the accretion disk near the hot spot. Line properties allow us to impose limits on the size of accretion disk, the central corona, and the emission region. The photo-ionized plasma is consistent with ionization parameters...

  3. Broad-band BeppoSAX observation of the low-mass X-ray binary X1822-371

    CERN Document Server

    Parmar, A N; Del Sordo, S; Segreto, A; Santangelo, A; Dal Fiume, D; Orlandini, M

    2000-01-01

    Results of a 1997 September 9-10 BeppoSAX observation of the 5.57 hr low-mass X-ray binary (LMXRB) X1822-371 are presented. The 0.3-40 keV spectrum is unusually complex and cannot be fit by any of the standard models applied to other LMXRB. At least two components are required. One component has a shape consistent with that expected from the Comptonization of an input soft (Wein) spectrum while the other, contributing ~40% of the 1-10 keV flux, is consistent with being a blackbody. In addition, there is a ``dip'' in the spectrum which can be modeled by a 1.33 +0.05 -0.11 keV absorption edge with an optical depth, tau, of 0.28 +/- 0.06. If the same model is fit to ASCA Solid-State Imaging Spectrometer spectra obtained in 1993 and 1996, then reasonable fits are also obtained, with a similar absorption feature required. The nature of this feature is highly uncertain; its energy corresponds to the K-edges of highly ionized Ne x and neutral Mg, or to an L-edge of moderately ionized Fe. Surprisingly, no strong (tau...

  4. Orbital and Spin Parameter Variations of Partial Eclipsing Low Mass X-ray Binary X 1822-371

    CERN Document Server

    Chou, Yi; Hu, Chin-Ping; Yang, Ting-Chang; Su, Yi-Hao

    2016-01-01

    We report our measurements for orbital and spin parameters of X 1822-371 using its X-ray partial eclipsing profile and pulsar timing from data collected by the Rossi X-ray Timing Explorer (RXTE). Four more X-ray eclipse times obtained by the RXTE 2011 observations were combined with historical records to trace evolution of orbital period. We found that a cubic ephemeris likely better describes evolution of the X-ray eclipse times during a time span of about 34 years with a marginal second order derivative of $\\ddot{P}_{orb}=(-1.05 \\pm 0.59) \\times 10^{-19}$ s$^{-1}$. Using the pulse arrival time delay technique, the orbital and spin parameters were obtained from RXTE observations from 1998 to 2011. The detected pulse periods show that the neutron star in X 1822-371 is continuously spun-up with a rate of $\\dot{P}_{s}=(-2.6288 \\pm 0.0095) \\times 10^{-12}$ s s$^{-1}$. Evolution of the epoch of the mean longitude $l=\\pi /2$ (i.e. $T_{\\pi / 2}$) gives an orbital period derivative value consistent with that obtaine...

  5. Multicolor flickering studies of X1822-371

    CERN Document Server

    Baptista, R; Harlaftis, E T; Baptista, Raymundo

    2002-01-01

    We report on the analysis of high-speed multicolor photometry of the eclipsing X-ray binary X1822-371. We used new eclipse timings to derive a revised optical ephemeris. A quadratic fit to the eclipse timings is not statistically significant but suggests that the orbital period is increasing on a timescale of P/|Pdot|= (4.2 +/- 1.4) 10^6 yr. We find no systematic delay or advance of the optical timings with respect to the X-ray timings. Average UBVRI light curves show the deep eclipse of the disc by the secondary star superimposed on the broader and shallower occultation of the inner disc regions by the outer disc (dip), and an orbital hump centred at phase +0.25 which is mostly seen in the U and B bands. The starting phase of the dip occurs earlier for shorter wavelengths, while the egress occurs at the same phase in all bands. This suggests that the thickening of the outer, occulting disc rim is gradual with azimuth at ingress but decreases sharply at egress. We fit synthetic photometry to the extracted col...

  6. X-ray spectroscopy of the ADC source X1822-371 with Chandra and XMM-Newton

    CERN Document Server

    Iaria, R; D'Aì, A; Burderi, L; Mineo, T; Riggio, A; Papitto, A; Robba, N R

    2012-01-01

    The eclipsing low-mass X-ray binary X1822-371 is the prototype of the accretion disc corona (ADC) sources. We analyse two Chandra observations and one XMM-Newton observation to study the discrete features and their variation as a function of the orbital phase, deriving constraints on the temperature, density, and location of the plasma responsible for emission lines. The HETGS and XMM/Epic-pn observed X1822-371 for 140 and 50 ks, respectively. We extracted an averaged spectrum and five spectra from five selected orbital-phase intervals that are 0.04-0.25, 0.25-0.50, 0.50-0.75, 0.75-0.95, and, finally, 0.95-1.04; the orbital phase zero corresponds to the eclipse time. All spectra cover the energy band between 0.35 and 12 keV. We confirm the presence of local neutral matter that partially covers the X-ray emitting region; the equivalent hydrogen column is $5 \\times 10^{22}$ cm$ ^{-2}$ and the covered fraction is about 60-65%. We identify emission lines from highly ionised elements, and a prominent fluorescence ...

  7. Detailed study of the X-ray and Optical/UV orbital ephemeris of X1822-371

    CERN Document Server

    Iaria, R; Burderi, L; D'Ai, A; Papitto, A; Riggio, A; Robba, N R; 10.1051/0004-6361/201117334

    2012-01-01

    Recent studies of the optical/UV and X-ray ephemerides of X1822-371 have found some discrepancies in the value of the orbital period derivative. Because of the importance of this value in constraining the system evolution, we comprehensively analyse all the available optical/UV/X eclipse times of this source to investigate the origin of these discrepancies. We collected all previously published X-ray eclipse times from 1977 to 2008, to which we added the eclipse time observed by Suzaku in 2006. This point is very important to cover the time gap between the last RXTE eclipse time (taken in 2003) and the most recent Chandra eclipse time (taken in 2008). Similarly we collected the optical/UV eclipse arrival times covering the period from 1979 to 2006, adding a further eclipse time taken on 1978 and updating previous optical/UV ephemeris. We compared the X-ray and the optical/UV ephemeris, and finally derived a new ephemeris of the source by combining the eclipse arrival times in the X-ray and optical/UV bands. T...

  8. ALMA observations of 4U 1728-34 and 4U 1820-30: first detection of neutron star X-ray binaries at 300 GHz

    CERN Document Server

    Trigo, M Diaz; Miller-Jones, J C A; Rahoui, F; Russell, D M; Tudor, V

    2016-01-01

    We report on the first observations of neutron star low-mass X-ray binaries with the Atacama Large Millimeter/submillimeter Array (ALMA) at $\\sim$300 GHz. Quasi-simultaneous observations of 4U 1728-34 and 4U 1820-30 were performed at radio (ATCA), infrared (VLT) and X-ray (Swift) frequencies, spanning more than eight decades in frequency coverage. Both sources are detected at high significance with ALMA. The spectral energy distribution of 4U 1728-34 is consistent with synchrotron emission from a jet with a break from optically thick to optically thin emission at 1.3-11.0$\\times$10$^{13}$ Hz. This is the third time a jet spectral break has been reported for a neutron star X-ray binary. The radio to mm spectral energy distribution of 4U 1820-30 has significant detections at 5 and 300~GHz. This confirms the presence of radio emission during a soft state for this neutron star and represents the first detection of mm emission during such a state, unambiguously pointing to the presence of a jet. We also report on ...

  9. Physical parameters of the high-mass X-ray binary 4U1700-37

    CERN Document Server

    Clark, J S; Crowther, P A; Kaper, L; Fairbairn, M; Langer, N; Brocksopp, C

    2002-01-01

    We present the results of a detailed non-LTE analysis of the UV and optical spectrum of the O6.5Iaf+ star HD153919 - the mass donor in the high-mass X-ray binary 4U1700-37. Given the eclipsing nature of the system these results allow us to determine the most likely masses of both components of the binary via Monte Carlo simulations. These suggest a mass for HD153919 of 58+/-11M_sun - implying the initial mass of the companion was rather high (>60 M_sun). The most likely mass for the compact companion is found to be 2.44+/-0.27M_sun, with only 3.5 per cent of the trials resulting in a mass less than 2.0M_sun and none less than 1.65M_sun. Our observational data is inconsistent with the canonical neutron star mass and the lowest black hole mass observed (>4.4M_sun; Nova Vel). Significantly changing observational parameters can force the compact object mass into either of these regimes but this results in the O-star mass changing by factors of greater than 2, well beyond the limits determined from its evolutionar...

  10. A new symbiotic low mass X-ray binary system: 4U 1954+319

    CERN Document Server

    Mattana, F; Falanga, M; Senziani, F; De Luca, A; Esposito, P; Caraveo, P A

    2006-01-01

    4U 1954+319 was discovered 25 years ago, but only recently has a clear picture of its nature begun to emerge. We present for the first time a broad-band spectrum of the source and a detailed timing study using more than one year of monitoring data. The timing and spectral analysis was done using publicly available Swift, INTEGRAL, BeppoSAX, and RXTE/ASM data in the 0.7-150 keV energy band. The source spectrum is described well by a highly absorbed (N_H~10^23 cm^-2) power law with a high-energy exponential cutoff around 15 keV. An additional black body component is needed below 3 keV to account for a soft excess. The derived ~5 hr periodicity, with a spin-up timescale of ~25 years, could be identified as the neutron star spin period. The spectral and timing characteristics indicate that we are dealing both with the slowest established wind-accreting X-ray pulsar and with the second confirmed member of the emerging class dubbed "symbiotic low mass X-ray binaries" to host a neutron star.

  11. Time lags of the kilohertz quasi-periodic oscillations in the low-mass X-ray binaries 4U 1608-52 and 4U 1636-53

    NARCIS (Netherlands)

    de Avellar, M. G. B.; Méndez, M.; Sanna, A.; Horvath, J. E.

    2014-01-01

    We studied the time lags and the coherence of the X-ray light curves of the neutron star low mass X-ray binaries 4U 1608-52 and 4U 1636-53. These quantities are frequency-dependent measures of the time or phase delay and of the degree of linear correlation between two X-ray light curves in two diffe

  12. A Comparison of the Variability of the Symbiotic X-ray Binaries GX 1+4, 4U 1954+31, and 4U 1700+24 from Swift/BAT and RXTE/ASM Observations

    Science.gov (United States)

    Corbet, R. H. D.; Sokoloski, J. L.; Mukai, K.; Markwardt, C. B.; Tueller, J.

    2007-01-01

    We present an analysis of the X-ray variability of three symbiotic X-ray binaries, GX 1+4, 4U 1700+24, and 4U 1954+31, using observations made with the Swift Burst Alert Telescope (BAT) and the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM). Observations of 4U 1954+31 with the Swift BAT show modulation at a period near 5 hours. Models to explain this modulation are discussed including the presence of an exceptionally slow X-ray pulsar in the system and accretion instabilities. We conclude that the most likely interpretation is that 4U 1954+31 contains one of the slowest known X-ray pulsars. Unlike 4U 1954+31, neither GX 1+4 nor 4U 1700+24 show any evidence for modulation on a timescale of hours. An analysis of the RXTE ASM light curves of GX l+4, 4U 1700+24, and 4U 1954+31 does not show the presence of periodic modulation in any source, although there is considerable variability on long timescales for all three sources. There is no modulation in GX 1+4 on either the optical 1161 day orbital period or a previously reported 304 day X-ray period. For 4U 1700+24 we do not confirm the 404 day period previously proposed for this source from a shorter duration ASM light curve.

  13. The BeppoSAX view on the Galactic Massive X-ray Binary 4U 0114+65

    CERN Document Server

    Masetti, N; Dal Fiume, D; Del Sordo, S; Amati, L; Frontera, F; Palazzi, E; Santangelo, A

    2005-01-01

    A pointed observation on the galactic high-mass X-ray binary 4U 0114+65 was carried out with BeppoSAX in order to compare the X-ray spectral and timing characteristics observed by this satellite over the broadest range of energies ever (1.5-100 keV) with the information previously obtained with other spacecraft. The light curve of 4U 0114+65 shows a large flare at the beginning of the BeppoSAX pointing and no significant hardness evolution either during the flare or in the low state occurring after the flare itself. The modulation at about 2.7 hours, attributed to the accreting neutron star (NS) spin periodicity, is not significantly detected in our data, although fluctuations with timescales of about 3 hours can be seen in the 2-10 keV light curve. Shorter modulations down to timescales of minutes, are also found and interpreted as due to accretion of matter onto the NS. The flaring and the low state spectra of 4U 0114+65 can be equally well fitted either with a power law modulated by a high-energy exponenti...

  14. Probing the Accretion Scheme of the Dipping X-ray Binary 4U 1915-05 with Suzaku

    CERN Document Server

    Zhang, Zhongli; Sakurai, Soki; Sasano, Makoto; Ono, Kou

    2014-01-01

    The dipping low-mass X-ray binary 4U 1915-05 was observed by Suzaku on 2007 November 8 for a net exposure of 39 ksec. It was detected by the XIS with a 0.8-10 keV signal rate of 9.84+\\-0.01 cts/s per camera, and HXD-PIN with a 12-45 keV signal rate of 0.29+/-0.01 cts/s. After removing the periodic dips and an X-ray burst, the 0.8 - 45 keV continuum was successfully described by an optically thick disk emission with an inner-disk temperature ~ 0.7 keV and a neutron-star blackbody emission with a temperature ~ 1.3 keV, on condition that the blackbody component, or possibly the disk emission too, is significantly Comptonized. This successful modeling is consistent with 4U 1915-05 being in a high-soft state in this observation, and implies that its broadband spectrum can be interpreted in the same scheme as for many non-dipping Low-mass X-ray binaries in the soft state. Its bolometric luminosity (~ 0.02 times the Eddington limit) is relatively low for the soft state, but within a tolerance, if considering the dis...

  15. Measurements of Cyclotron Features and Pulse Periods in the High-Mass X-Ray Binaries 4U 1538-522 and 4U 1907+09 with the International Gamma-Ray Astrophysics Laboratory

    Science.gov (United States)

    Hemphill, Paul B.; Rothschild, Richard E.; Caballero, Isabel; Pottschmidt, Katja; Kuhnel, Matthias; Furst, Felix; Wilms, Jorn

    2013-01-01

    We present a spectral and timing analysis of International Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of two high-mass X-ray binaries, 4U 1538-522 and 4U 1907+09. Our timing measurements for 4U 1538-522 find the pulse period to have exhibited a spin-up trend until approximately 2009, after which there is evidence for a torque reversal, with the source beginning to spin down to the most recently measured period of 525.407 plus or minus 0.001 seconds. The most recent INTEGRAL observations of 4U 1907+09 are not found to yield statistically significant pulse periods due to the significantly lower flux from the source compared with 4U 1538-522. A spectral model consisting of a power-law continuum with an exponential cutoff and modified by two cyclotron resonance scattering features is found to fit both sources well, with the cyclotron scattering features detected at approximately 22 and approximately 49 kiloelectronvolts for 4U 1538-522 and at approximately 18 and approximately 36 kiloelectronvolts for 4U 1907+09. The spectral parameters of 4U 1538-522 are generally not found to vary significantly with flux and there is little to no variation across the torque reversal. Examining our results in conjunction with previous work, we find no evidence for a correlation between cyclotron line energy and luminosity for 4U 1538-522. 4U 1907+09 shows evidence for a positive correlation between cyclotron line energy and luminosity, which would make it the fourth, and lowest luminosity, cyclotron line source to exhibit this relationship.

  16. $\\delta$-invariant for Quasi-periodic Oscillations and Physical Parameters of 4U 0614+09 binary

    CERN Document Server

    Titarchuk, L G; Titarchuk, Lev; Osherovich, Vladimir

    2000-01-01

    The recently formulated Two Oscillator (TO) model interprets the lowest of the kilohertz frequencies of the twin peak quasi-periodic oscillations in X -ray binaries as the Keplerian frequency nu_K. The high twin frequency nu_h in this model holds the upper hybrid frequency relation to the rotational frequency of the neutron star's magnetosphere Omega: nu_h^2=nu_K^2+ 4(Omega/2pi)^2. The vector Omega is assumed to have an angle delta with the normal to the disk. The first oscillator in the TO model allows one to interpret the horizontal branch observed below 100 Hz as the lower mode of the Keplerian oscillator under the influence of the Coriolis force, with frequency nu_L being dependent on nu_h, nu_K and delta. For some stars such as 4U 0614+09, Sco X-1 and 4U 1702-42, nu_h, nu_K and nu_L have been observed simultaneously providing the opportunity to check the central prediction of the TO model: the constancy of delta for a particular source. Given the considerable variation of each of these three frequencies,...

  17. Following the Colour of the Low Mass X-ray Binary 4U 1820-30 with INTEGRAL

    CERN Document Server

    Tarana, A; Ubertini, P; Zdziarski, A A; Federici, M; Tarana, Antonella; Bazzano, Angela; Ubertini, Pietro

    2006-01-01

    The 4-200 keV spectral and temporal behaviour of the low mass X-ray binary 4U 1820-30 has been studied with INTEGRAL during 2003-2005. This source as been observed in both the soft (banana) and hard (island) spectral states. A high energy tail above 50 keV in the hard state has been revealed for the first time. This places the source in the category of X-ray bursters showing high-energy emission. The tail can be modeled as a soft power law component, with the photon index of ~ 2.4, on top of thermal Comptonization emission from a plasma with the electron temperature of kT_e ~ 6 keV and optical depth of $\\tau ~ 4. Alternatively, but at a lower goodness of the fit, the hard-state broad band spectrum can be accounted for by emission from a hybrid, thermal-nonthermal, plasma. During the observations, the source spent most of the time in the soft state, as previously reported and the $\\ge$4 keV spectra can be represented by thermal Comptonization with kT_e ~ 3 keV and $\\tau ~ 6-7.

  18. Polarimetric and spectroscopic optical observations of the ultra-compact X-ray binary 4U 0614+091

    CERN Document Server

    Baglio, M C; D'Avanzo, P; Campana, S; Covino, S; Russell, D M; Shahbaz, T

    2014-01-01

    Aims: We present a polarimetric and spectroscopic study of the persistent ultra compact X-ray binary 4U 0614+091 aimed at searching for the emission of a relativistic particle jet and at unveiling the orbital period of the system. Methods: We obtained r-band polarimetric observations with the Telescopio Nazionale Galileo (TNG) equipped with the PAOLO polarimeter and with the Nordic Optical Telescope (NOT) equipped with the ALFOSC instrument, covering ~ 2 hours and ~ 0.5 hours observations, respectively. We carried out low resolution spectroscopy of the system using the ESO Very Large Telescope equipped with FORS1 for ~ 1.5 hours (16 spectra covering the range 430-800 nm). Results: The polarimetric analysis performed starting from the TNG dataset revealed a polarisation degree in the r-band of 3 % +/- 1 %. From the NOT dataset, due to the lower S/N ratio, we could obtain only a 3 sigma upper limit of 3.4 %. From the joining of a spectroscopic and photometric analysis, through the study of the equivalent width ...

  19. Spectral and timing nature of the symbiotic X-ray binary 4U 1954+319: The slowest rotating neutron star in an X-ray binary system

    Energy Technology Data Exchange (ETDEWEB)

    Enoto, Teruaki; Corbet, Robin H. D. [NASA Goddard Space Flight Center, Astrophysics Science Division, Code 662, Greenbelt, MD 20771 (United States); Sasano, Makoto [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yamada, Shin' ya; Tamagawa, Toru; Makishima, Kazuo [High Energy Astrophysics Laboratory, RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Pottschmidt, Katja; Marcu, Diana [NASA Goddard Space Flight Center, Astrophysics Science Division, Code 661, Greenbelt, MD 20771 (United States); Fuerst, Felix [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Wilms, Jörn, E-mail: teruaki.enoto@nasa.gov [Dr. Remeis-Sternwarte and Erlangen Centre for Astroparticle Physics, Universität Erlangen-Nürnberg, Sternwartstr. 7, D-96049 Bamberg (Germany)

    2014-05-10

    The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its ∼5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (∼7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-Kα line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (∼60%-80%), and the location in the Corbet diagram favor high B-field (≳ 10{sup 12} G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10{sup 33}-10{sup 35} erg s{sup –1}), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a ∼10{sup 13} G NS, this scheme can explain the ∼5.4 hr equilibrium rotation without employing the magnetar-like field (∼10{sup 16} G) required in the disk accretion case. The timescales of multiple irregular flares (∼50 s) can also be attributed to the free-fall time from the Alfvén shell for a ∼10{sup 13} G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

  20. Spectral and Timing Nature of the Symbiotic X-Ray Binary 4U 1954+319: The Slowest Rotating Neutron Star in AN X-Ray Binary System

    Science.gov (United States)

    Enoto, Teruaki; Sasano, Makoto; Yamada, Shin'Ya; Tamagawa, Toru; Makishima, Kazuo; Pottschmidt, Katja; Marcu, Diana; Corbet, Robin H. D.; Fuerst, Felix; Wilms, Jorn

    2014-01-01

    The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its approx. 5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (is approx. 7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-K alpha line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (approx. 60%-80%), and the location in the Corbet diagram favor high B-field (approx. greater than 10(exp12) G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10(exp33)-10(exp35) erg s(exp-1)), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a approx. 10(exp13) G NS, this scheme can explain the approx. 5.4 hr equilibrium rotation without employing the magnetar-like field (approx. 10(exp16) G) required in the disk accretion case. The timescales of multiple irregular flares (approx. 50 s) can also be attributed to the free-fall time from the Alfv´en shell for a approx. 10(exp13) G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

  1. Spitzer Reveals Infrared Optically-Thin Synchrotron Emission from the Compact Jet of the Neutron Star X-Ray Binary 4U 0614+091

    NARCIS (Netherlands)

    Migliari, S.; Tomsick, J.A.; Maccarone, T.J.; Gallo, E.; Fender, R.P.; Nelemans, G.; Russell, D.M.

    2006-01-01

    Spitzer observations of the neutron star (ultracompact) X-ray binary (XRB) 4U 0614+091 with the Infrared Array Camera reveal emission of nonthermal origin in the range 3.5-8 mum. The mid-infrared spectrum is well fit by a power law with spectral index of alpha=-0.57+/-0.04 (where the flux density is

  2. A NuSTAR observation of the reflection spectrum of the low-mass X-ray binary 4U 1728-34

    DEFF Research Database (Denmark)

    Sleator, Clio C.; Tomsick, John A.; King, Ashley L.

    2016-01-01

    We report on a simultaneous NuSTAR and Swift observation of the neutron star low-mass X-ray binary 4U 1728-34. We identified and removed four Type I X-ray bursts during the observation in order to study the persistent emission. The continuum spectrum is hard and described well by a blackbody with k...

  3. Broadband X-ray emission and the reality of the broad iron line from the Neutron Star - White Dwarf X-ray binary 4U 1820-30

    CERN Document Server

    Mondal, Aditya S; Pahari, Mayukh; Misra, Ranjeev; Kembhavi, Ajit K; Raychaudhuri, Biplab

    2016-01-01

    Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disk. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here we investigate the reality of the broad iron line detected earlier from the neutron star low mass X-ray binary 4U~1820--30 with a degenerate helium dwarf companion. We perform a comprehensive, systematic broadband spectral study of the atoll source using \\suzaku{} and simultaneous \

  4. Spitzer Reveals Infrared Optically-Thin Synchrotron Emission from the Compact Jet of the Neutron Star X-Ray Binary 4U 0614+091

    OpenAIRE

    Migliari, S.; Tomsick, J.A.; Maccarone, T.J.; Gallo, E.; Fender, R. P.; Nelemans, G; Russell, D. M.

    2006-01-01

    Spitzer observations of the neutron star (ultracompact) X-ray binary (XRB) 4U 0614+091 with the Infrared Array Camera reveal emission of nonthermal origin in the range 3.5-8 mum. The mid-infrared spectrum is well fit by a power law with spectral index of alpha=-0.57+/-0.04 (where the flux density is Fnu~nualpha). Given the ultracompact nature of the binary system, we exclude the possibility that either the companion star or the accretion disk can be the origin of the observed emission. These ...

  5. Relativistic Iron Line Emission from the Neutron Star Low-mass X-ray Binary 4U 1636-536

    OpenAIRE

    Pandel, Dirk; Kaaret, Philip; Corbel, Stephane

    2008-01-01

    We present an analysis of XMM-Newton and RXTE data from three observations of the neutron star LMXB 4U 1636-536. The X-ray spectra show clear evidence of a broad, asymmetric iron emission line extending over the energy range 4-9 keV. The line profile is consistent with relativistically broadened Fe K-alpha emission from the inner accretion disk. The Fe K-alpha line in 4U 1636-536 is considerably broader than the asymmetric iron lines recently found in other neutron star LMXBs, which indicates...

  6. Spectral and Timing Properties of the Low-mass X-ray Binary 4U 0614+09 with XMM-Newton

    CERN Document Server

    Méndez, M; Paerels, F B S; Cottam, Jean

    2002-01-01

    4U 0614+09 is a low-mass X-ray binary with a weakly magnetized neutron star primary. It shows variability on time scales that range from years down to ~0.8 milliseconds. Before the Chandra and XMM-Newton era, emission features around 0.7 keV have been reported from this source, but recent Chandra observations failed to detect them. Instead, these observations suggest an overabundance of Ne in the absorbing material, which may be common to ultracompact (P_{orb} \\simless 1 hour) systems with a neon-rich degenerate dwarf secondary. We observed 4U 0614+09 with XMM-Newton in March 2001. Here we present the energy spectra, both from the RGS and EPIC cameras, and the Fourier power spectra from EPIC high-time resolution light curves, which we use to characterize the spectral state of the source.

  7. Luminosity Dependent Study of the High Mass X-ray Binary Pulsar 4U 0114 + 65 with ASCA

    Indian Academy of Sciences (India)

    U. Mukherjee; B. Paul

    2006-03-01

    Here we report the spectral characteristics of the high and low states of the pulsar 4U 0114+65 and examine the change in the parameters of the spectral model. A power lawand a photoelectric absorption by material along the line of sight together with a high energy cut-off suffice to describe the continuum spectrum in both the states. A fluorescence iron line at ∼ 6.4 keV is present in the high as well as in the low state, though it is less intense in the latter. The photon index, cut-off energy and e-folding energy values hardly show any discernible change over the states. We compare these spectral characteristics as observed with ASCA with those of other satellites. We also compare the spectral characteristics of 4U 0114 + 650 with other X-ray sources which show intensity variation at different time scales.

  8. A Circumbinary Disk Scenario for the Negative Orbital-period Derivative of the Ultra-compact X-Ray Binary 4U 1820-303

    Science.gov (United States)

    Jiang, Long; Chen, Wen-Cong; Li, Xiang-Dong

    2017-03-01

    It is generally thought that an ultra-compact X-ray Binary is composed of a neutron star and a helium white dwarf donor star. As one of the most compact binaries, 4U 1820-303 in globular cluster NGC 6624 was predicted to have an orbital period of \\dot{P}/P∼ 1.1× {10}-7 yr‑1 if the mass transfer is fully driven by gravitational radiation. However, recent analysis of 16 year data from Rossi X-ray Timing Explorer and other historical records has yielded a negative orbital-period derivative in the past 35 years. In this work, we propose an evolutionary circumbinary (CB) disk model to account for this anomalous orbital-period derivative. 4U 1820-30 is known to undergo superburst events caused by runaway thermal nuclear burning on the neutron star. We assume that, for a small fraction of the superbursts, part of the ejected material may form a CB disk around the binary. If the recurrence time of such superbursts is ∼10,000 year and ∼10% of the ejected mass feeds a CB disk, the abrupt angular-momentum loss causes a temporary orbital shrink, and the donor’s radius and its Roche lobe radius do not keep in step. Driven by mass transfer and angular-momentum loss, the binary would adjust its orbital parameters to recover a new stable stage. Based on theoretical analysis and numerical simulation, we find that the required feed mass at the CB disk is approximately ∼10‑8 M ⊙.

  9. Very-high-energy observations of the binaries V 404 Cyg and 4U 0115+634 during giant X-ray outbursts

    CERN Document Server

    Archer, A; Bird, R; Bourbeau, E; Buchovecky, M; Buckley, J H; Bugaev, V; Byrum, K; Cerruti, M; Connolly, M P; Cui, W; Errando, M; Falcone, A; Feng, Q; Fernandez-Alonso, M; Finley, J P; Fleischhack, H; Flinders, A; Fortson, L; Furniss, A; Griffin, S; Grube, J; Hütten, M; Hanna, D; Hervet, O; Holder, J; Humensky, T B; Johnson, C A; Kaaret, P; Kar, P; Kelley-Hoskins, N; Kertzman, M; Kieda, D; Krause, M; Kumar, S; Lang, M J; Lin, T T Y; Maier, G; Moriarty, P; Mukherjee, R; Nieto, D; O'Brien, S; Ong, R A; Park, N; Pohl, M; Popkow, A; Pueschel, E; Quinn, J; Ragan, K; Reynolds, P T; Richards, G T; Roache, E; Rousselle, J; Rovero, A C; Sadeh, I; Schlenstedt, S; Sembroski, G H; Shahinyan, K; Staszak, D; Telezhinsky, I; Tyler, J; Wakely, S P; Wilcox, P; Wilhelm, A; Williams, D A

    2016-01-01

    Transient X-ray binaries produce major outbursts in which the X-ray flux can increase over the quiescent level by factors as large as $10^7$. The low-mass X-ray binary V 404 Cyg and the high-mass system 4U 0115+634 underwent such major outbursts in June and October 2015, respectively. We present here observations at energies above hundreds of GeV with the VERITAS observatory taken during some of the brightest X-ray activity ever observed from these systems. No gamma-ray emission has been detected by VERITAS in 2.5 hours of observations of the microquasar V 404 Cyg from 2015, June 20-21. The upper flux limits derived from these observations on the gamma-ray flux above 200 GeV of F $< 4.4\\times 10^{-12}$ cm$^{-2}$ s$^{-1}$ correspond to a tiny fraction (about $10^{-6}$) of the Eddington luminosity of the system, in stark contrast to that seen in the X-ray band. No gamma rays have been detected during observations of 4U 0115+634 in the period of major X-ray activity in October 2015. The flux upper limit deriv...

  10. Non-radial pulsations in the Be/X binaries 4U0115+63 and SAXJ2103.5+4545

    CERN Document Server

    Gutiérrez-Soto, J; Fabregat, J; Fox-Machado, L

    2010-01-01

    The discovery of non-radial pulsations (NRP) in the Be/X binaries of the Magellanic Clouds (MC, eg. Fabrycky 2005, Coe et al. 2005, Schmidtke & Cowley 2005) provided a new approach to understand these complex systems, and, at the same time, favoured the synergy between two different fields: stellar pulsations and X-ray binaries. This breakthrough was possible thanks to the MACHO and OGLE surveys. However, in our Galaxy, only two Be/X have been reported to show NRP: GROJ2058+42 (Kiziloglu et al. 2007) and LSI+61 235 (Sarty et al. 2009). Our objective is to study the short-term variability of Galactic Be/X binaries, compare them to the Be/X of the MC and to the isolated Galactic Be observed with CoRoT and Kepler. We present preliminary results of two Be/X stars, namely 4U0115+63 and SAXJ2103.5+4545 showing multiperiodicity and periodicity respectively, most probably produced by non-radial pulsations.

  11. A relativistically broadened O VIII Lyalpha line in the ultra-compact X-ray binary 4U 0614+091

    CERN Document Server

    Madej, O K; Fabian, A C; Pinto, C; Verbunt, F; de Plaa, J

    2010-01-01

    Ultra-compact X-ray binaries consist of a neutron star or black hole that accretes material from a white dwarf-donor star. The ultra-compact nature is expressed in very short orbital periods of less than 1 hour. In the case of 4U 0614+091 oxygen-rich material from a CO or ONe white dwarf is flowing to the neutron star. This oxygen-rich disc can reflect X-rays emitted by the neutron star giving a characteristic emission spectrum. We have analyzed high-resolution RGS and broad band EPIC spectra of 4U 0614+091 obtained by the XMM-Newton satellite. We detect a broad emission feature at ~0.7 keV in both instruments, which cannot be explained by unusual abundances of oxygen and neon in the line of sight, as proposed before in the literature. We interpret this feature as O VIII Lyalpha emission caused by reflection of X-rays off highly ionized oxygen, in the strong gravitational field close to the neutron star.

  12. Discovery of type-I X-ray bursts from the low-mass X-ray binary 4U 1708-40

    CERN Document Server

    Migliari, S; Belloni, T; Van der Klis, M; Fender, R P; Campana, S; Kouveliotou, C; Méndez, M; Lewin, W H G

    2003-01-01

    We report the discovery of type-I X-ray bursts from the low-mass X-ray binary 4U 1708-40 during the 100 ks observation performed by BeppoSAX on 1999 August 15-16. Six X-ray bursts have been observed. The unabsorbed 2-10 keV fluxes of the bursts range from ~ (3-9)x10^(-10) erg cm^(-2)s^(-1). A correlation between peak flux and fluence of the bursts is found, in agreement with the behaviour observed in other similar sources. There is a trend of the burst flux to increase with the time interval from the previous burst. From the value of the persistent flux we infer a mass accretion rate Mdot~7x10^(-11) Msun/yr, that may correspond to the mixed hydrogen/helium burning regime triggered by thermally unstable hydrogen. We have also analysed a BeppoSAX observation performed on 2001 August 22 and previous RXTE observations of 4U 1708-40, where no bursts have been observed; we found persistent fluxes of more than a factor of 7 higher than the persistent flux observed during the BeppoSAX observation showing X-ray bursts...

  13. The Quiescent Neutron Star and Hierarchical Triple, 4U2129+47

    Science.gov (United States)

    Nowak, Michael; Chakrabarty, Deepto; Wilms, Joern; Kühnel, Matthias

    2016-04-01

    4U 2129+47 is a quiescent, eclipsing neutron star that 35 years ago showed typical "Accretion Disk Corona" (ADC) behavior akin to the prototype of the class, X1822-371. Now faded, 4U 2129+47 provides tests of neutron star quiescent emission. It has shown low temperature thermal emission (the neutron star surface), a power law tail (of unknown origin, although possibly due to a pulsar wind interacting with an incoming accretion stream; Campana et al. 1998), and sinusoidally modulated absorption (the disk) as well as periodic X-ray eclipses. Subsequent XMM-Newton and Chandra observations, taken 2007 through Fall 2015, indicate that the hard tail and sinusoidal modulation disappeared, as if the accretion stream and disk have vanished. With the intiial loss of the hard tail, the soft X-ray flux also dropped, but since has remained steady, showing no signs of further neutron star cooling in the subsequent 8 years. We compare this behavior to recent NuSTAR observations of the quiescent neutron star Cen X-4, where the hard tail seems to persist over a wider range of quiescent flux, and correlate with the soft X-ray. It also has been speculated that 4U 2129+47 is part of a hierarchical triple system, with the third body in a much longer orbit. We use the Chandra and XMM-Newton eclipse ephemeris residuals to describe this third body orbit.

  14. Very High Energy Observations of the Binaries V 404 Cyg and 4U 0115+634 during Giant X-Ray Outbursts

    Science.gov (United States)

    Archer, A.; Benbow, W.; Bird, R.; Bourbeau, E.; Buchovecky, M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cerruti, M.; Connolly, M. P.; Cui, W.; Errando, M.; Falcone, A.; Feng, Q.; Fernandez-Alonso, M.; Finley, J. P.; Fleischhack, H.; Flinders, A.; Fortson, L.; Furniss, A.; Griffin, S.; Grube, J.; Hütten, M.; Hanna, D.; Hervet, O.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Kumar, S.; Lang, M. J.; Lin, T. T. Y.; Maier, G.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Brien, S.; Ong, R. A.; Park, N.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rousselle, J.; Rovero, A. C.; Sadeh, I.; Schlenstedt, S.; Sembroski, G. H.; Shahinyan, K.; Staszak, D.; Telezhinsky, I.; Tyler, J.; Wakely, S. P.; Wilcox, P.; Wilhelm, A.; Williams, D. A.

    2016-11-01

    Transient X-ray binaries produce major outbursts in which the X-ray flux can increase over the quiescent level by factors as large as 107. The low-mass X-ray binary V 404 Cyg and the high-mass system 4U 0115+634 underwent such major outbursts in 2015 June and October, respectively. We present here observations at energies above hundreds of GeV with the VERITAS observatory taken during some of the brightest X-ray activity ever observed from these systems. No gamma-ray emission has been detected by VERITAS in 2.5 hr of observations of the microquasar V 404 Cyg from 2015, June 20-21. The upper flux limits derived from these observations on the gamma-ray flux above 200 GeV of F \\lt 4.4× {10}-12 cm-2 s-1 correspond to a tiny fraction (about 10-6) of the Eddington luminosity of the system, in stark contrast to that seen in the X-ray band. No gamma-rays have been detected during observations of 4U 0115+634 in the period of major X-ray activity in 2015 October. The flux upper limit derived from our observations is F \\lt 2.1× {10}-12 cm-2 s-1 for gamma-rays above 300 GeV, setting an upper limit on the ratio of gamma-ray to X-ray luminosity of less than 4%.

  15. Spitzer Reveals Infrared Optically Thin Synchrotron Emission from the Compact Jet of the Neutron Star X-Ray Binary 4U 0614+091

    Science.gov (United States)

    Migliari, S.; Tomsick, J. A.; Maccarone, T. J.; Gallo, E.; Fender, R. P.; Nelemans, G.; Russell, D. M.

    2006-05-01

    Spitzer observations of the neutron star (ultracompact) X-ray binary (XRB) 4U 0614+091 with the Infrared Array Camera reveal emission of nonthermal origin in the range 3.5-8 μm. The mid-infrared spectrum is well fit by a power law with spectral index of α=-0.57+/-0.04 (where the flux density is Fν~να). Given the ultracompact nature of the binary system, we exclude the possibility that either the companion star or the accretion disk can be the origin of the observed emission. These observations represent the first spectral evidence for a compact jet in a low-luminosity neutron star XRB and furthermore of the presence, already observed in two black hole (BH) XRBs, of a ``break'' in the synchrotron spectrum of such compact jets. We can derive a firm upper limit on the break frequency of the spectrum of νthin=3.7×1013 Hz, which is lower than that observed in BH XRBs by at least a factor of 10. Assuming a high-energy cooling cutoff at ~1 keV, we estimate a total (integrated up to X-rays) jet power to X-ray bolometric luminosity ratio of ~5%, much lower than that inferred in BHs.

  16. Spitzer Reveals Infrared Optically-Thin Synchrotron Emission from the Compact Jet of the Neutron Star X-Ray Binary 4U 0614+091

    CERN Document Server

    Migliari, S; Gallo, E; Maccarone, T J; Nelemans, G; Russell, D M; Tomsick, J A

    2006-01-01

    Spitzer observations of the neutron star (ultra-compact) X-ray binary (XRB) 4U 0614+091 with the Infrared Array Camera reveal emission of non-thermal origin in the range 3.5-8 um. The mid-infrared spectrum is well fit by a power law with spectral index of alpha=-0.57+/-0.04 (where the flux density is F_nu \\propto nu^(alpha)). Given the ultra-compact nature of the binary system, we exclude the possibility that either the companion star or the accretion disk can be the origin of the observed emission. These observations represent the first spectral evidence for a compact jet in a low-luminosity neutron star XRB and furthermore of the presence, already observed in two black hole (BH) XRBs, of a `break' in the synchrotron spectrum of such compact jets. We can derive a firm upper limit on the break frequency of the spectrum of nu_thin=3.7x10^(13) Hz, which is lower than that observed in BH XRBs by at least a factor of 10. Assuming a high-energy cooling cutoff at ~1 keV, we estimate a total (integrated up to X-rays...

  17. Phase lags of quasi-periodic oscillations across source states in the low-mass X-ray binary 4U 1636-53

    CERN Document Server

    de Avellar, Marcio G B; Altamirano, Diego; Sanna, Andrea; Zhang, Guobao

    2016-01-01

    While there are many dynamical mechanisms and models that try to explain the origin and phenomenology of the quasi-periodic oscillations (QPOs) seen in the X-ray light curves of low-mass X-ray binaries, few of them address how the radiative processes occurring in these extreme environments give rise to the rich set of variability features actually observed in these light curves. A step towards this end comes from the study of the energy and frequency dependence of the phase lags of these QPOs. Here we used a methodology that allowed us to study, for the first time, the dependence of the phase lags of all QPOs in the range of 1 Hz to 1300 Hz detected in the low-mass X-ray binary 4U 1636-53 upon energy and frequency as the source changes its states as it moves through the colour-colour diagram. Our results suggest that within the context of models of up-scattering Comptonization, the phase lags dependencies upon frequency and energy can be used to extract size scales and physical conditions of the medium that p...

  18. Time lags of the kilohertz quasi-periodic oscillations in the low-mass X-ray binaries 4U 1608--52 and 4U 1636--53

    CERN Document Server

    de Avellar, M G B; Sanna, A; Horvath, J E

    2013-01-01

    (abridged) We studied the energy and frequency dependence of the Fourier time lags and intrinsic coherence of the kHz QPOs in the NS LMXBs 4U 1608-52 and 4U 1636-53 using RXTE data. In both sources we confirmed energy-dependent soft lags of 10-100 \\mu s for the lower kHz QPO. We also found that the time lags of the upper kHz QPO are independent of energy and inconsistent with the soft lags of the lower kHz QPO. The intrinsic coherence of the lower kHz QPO remains constant at 0.6 from 5 to 12 keV, and then drops to zero, while for the upper kHz QPO the intrinsic coherence is consistent with zero across the full energy range. The intrinsic coherence of the upper kHz QPO is consistent with zero over the full frequency range of the QPO, except in 4U 1636-53 at ~780 Hz where it increases to 0.13. In 4U 1636-53, for the lower kHz QPO the 4-12 keV photons lag the 12-20 keV ones by 25 \\mu s in the QPO frequency range 500-850 Hz, with the lags decreasing to 15 \\mu s at higher frequencies. In 4U 1608-52 the soft lags o...

  19. NuSTAR and SWIFT joint view of neutron star X-ray binary 4U 1728-34 : Disc reflection in the island and lower banana states

    Science.gov (United States)

    Mondal, Aditya S.; Pahari, Mayukh; Dewangan, G. C.; Misra, R.; Raychaudhuri, B.

    2017-01-01

    We analyze two simultaneous NuSTAR and SWIFT data of the Atoll type neutron star (NS) X-ray binary 4U 1728-34 observed on 1 and 3 October, 2013. We infer that the first and the second observations belong to the island state and the lower banana state respectively. During island state, four type-I X-ray bursts are observed within 60 ks exposure. From the time-resolved spectral analysis of each burst with NuSTAR, the blackbody temperature kTbb are found to vary between 1.3 to 3.0 keV while the blackbody normalizations (km/10 kpc)2 vary in the range 20 to 200, which translates to blackbody radii of 3.5 - 7.4 km for an assumed distance of 5 kpc. The persistent, joint energy spectra from SWIFT and NuSTAR for both observations in the energy band 1 - 79 keV are well described with thermal emission from the NS surface (kTbb ≃ 1 - 2.5 keV), Comptonized emission of thermal seed photons from the hot boundary layer/corona and the strong reflection component from the accretion disc. We detect a broad Iron line in the 5 - 8 keV band and reflection hump in the 15 - 30 keV band modelled by the relxill reflection model. Joint spectral fitting constrains the inclination angle of the binary system and inner disc radius to be 22 - 40 and (2.0 - 4.3) × RISCO, respectively. We estimate the magnetic field to be (1.8 - 6.5) × 108 Gauss. The X-ray luminosity of the source during the island and lower banana states are found to be LX = 1.1 and 1.6 × 1037 erg s-1 respectively which correspond to ˜6% and ˜9% of the Eddington luminosity.

  20. New Results on the Time lags of the Quasi-Periodic Oscillations in the Low-mass X-ray Binary 4U 1636--53

    CERN Document Server

    de Avellar, Marcio G B; Altamirano, Diego; Sanna, Andrea; Zhang, Guobao

    2015-01-01

    We present an analysis of the energy and frequency dependence of the Fourier time lags of the hectoHertz quasi-periodic oscillations (QPOs) and of the QPOs at the frequency at which the power density spectrum shows a break in the neutron-star low-mass X-ray binary 4U 1636-53, using a large data set obtained with the Rossi X-ray Timing Explorer. We found that: (i) For the break frequency QPO: for low frequencies, in general the time lag is positive, but it is decreasing with increasing frequency, reaching zero lag at 20 Hz. Between 20 and 35 Hz there is a small fluctuation around zero, from where the time lags become positive again and increase slightly above zero up to 65 Hz. (ii) For the hHz QPO: we see that when the frequency is 100 Hz the time lag is negative, but it increases to zero already at 110 Hz, being consistent with this value up to 130 Hz from where it increases to 0.5 msec at around 140 Hz. From 140 Hz the time lag decreases sharply, being strongly negative for hHz greater than 220 Hz. We compar...

  1. Discovery of a broad O VIII Ly alpha line in the ultra-compact X-ray binary 4U 1543-624

    CERN Document Server

    Madej, O K

    2010-01-01

    We report the discovery of a broad emission feature at ~0.7 keV in the spectra of the ultra-compact X-ray binary 4U 1543-624, obtained with the high-resolution spectrographs of the XMM-Newton and Chandra satellites. We confirm the presence of the feature in the broad band MOS2 spectrum of the source. As suggested before in the literature, the donor star in this source is a CO or ONe white dwarf, which transfers oxygen-rich material to the accretor, conceivably a neutron star. The X-rays reprocessed in this oxygen-rich accretion disc could give a reflection spectrum with O VIII Ly alpha as the most prominent emission line. Apart from the feature at ~0.7 keV we confirm the possible presence of a weak emission feature at ~6.6 keV, which was reported in the literature for this data set. We interpret the feature at ~0.7 keV and ~6.6 keV as O VIII Ly alpha and Fe K alpha emission respectively, caused by X-rays reflected off the accretion disc in the strong gravitational field close to the accretor.

  2. Probing the Mysteries of the X-Ray Binary 4U 1210-64 with ASM, PCA, MAXI, BAT and Suzaku

    CERN Document Server

    Coley, Joel B; Mukai, Koji; Pottschmidt, Katja

    2014-01-01

    4U 1210-64 has been postulated to be a High-Mass X-ray Binary powered by the Be mechanism. X-ray observations with Suzaku, the ISS Monitor of All-sky X-ray Image (MAXI) and the Rossi X-ray Timing Explorer Proportional Counter Array (PCA) and All Sky Monitor (ASM) provide detailed temporal and spectral information on this poorly understood source. Long term ASM and MAXI observations show distinct high and low states and the presence of a 6.7101 +/- 0.0005 day modulation, interpreted as the orbital period. Folded light curves reveal a sharp dip, interpreted as an eclipse. To determine the nature of the mass donor, the predicted eclipse half-angle was calculated as a function of inclination angle for several stellar spectral types. The eclipse half-angle is not consistent with a mass donor of spectral type B5 V; however, stars with spectral types B0 V or B0-5 III are possible. The best-fit spectral model consists of a power law with index gamma = 1.85 (+0.04,-0.05) and a high-energy cutoff at 5.5 +/- 0.2 keV mod...

  3. X-Ray Spectra of The High-Mass X-RAY Binary 4U~1700-37 using BeppoSAX, Suzaku and RXTE Observations

    CERN Document Server

    Seifina, Elena; Shaposhnikov, Nikolai

    2016-01-01

    We present an X-ray spectral analysis of the high-mass binary 4U~1700-37 during its hard-soft state evolution. We use the BeppoSAX, Suzaku and RXTE (Rossi X-ray Timing Explorer), Suzaku and BeppoSAX observations for this investigation. We argue that the X-ray broad-band spectra during all spectral states can be adequately reproduced by a model, consisting of a low-temperature Blackbody component, two Comptonized components both due to the presence of a Compton cloud (CC) that up-scatters seed photons of $T_{s1}$~< 1.4 keV, and $T_{s2}<$1 keV, and an iron-line component. We find using this model that the photon power-law index is almost constant, $\\Gamma_{1}\\sim 2$ for all spectral states. However, $\\Gamma_{2}$ shows a behavior depending on the spectral state. Namely, $\\Gamma_{2}$ is quasi-constant at the level of $\\Gamma_{2}\\sim 2$ while the CC plasma temperature $kT^{(2)}_e$ is less than 40 keV; on the other hand, $\\Gamma_{2}$ is in the range of $1.3<\\Gamma_{2}<2$, when $kT^{(2)}_e$ is greater th...

  4. Application of the Ghosh & Lamb Relation to the Spin-up/down Behavior in the X-ray Binary Pulsar 4U 1626-67

    CERN Document Server

    Takagi, Toshihiro; Sugizaki, Mutsumi; Makishima, Kazuo; Morii, Mikio

    2016-01-01

    We analyzed continuous MAXI/GSC data of the X-ray binary pulsar 4U 1626-67 from 2009 October to 2013 September, and determined the pulse period and the pulse-period derivative for every 60-d interval by the epoch folding method. The obtained periods are consistent with those provided by the Fermi/GBM pulsar project. In all the 60-d intervals, the pulsar was observed to spin up, with the spin-up rate positively correlated with the 2-20 keV flux. We applied the accretion torque model proposed by Ghosh & Lamb (1979, ApJ, 234, 296) to the MAXI/GSC data, as well as the past data including both spin-up and spin-down phases. The Ghosh & Lamb relation was confirmed to successfully explain the observed relation between the spin-up/down rate and the flux. By comparing the model-predicted luminosity with the observed flux, the source distance was constrained as 5-13 kpc, which is consistent with that by Chakrabarty (1998, ApJ, 492, 342). Conversely, if the source distance is assumed, the data can constrain the m...

  5. A multiwavelength approach to BD+53$^\\circ$2790: the O9.5V counterpart to the X-ray binary system 4U~2206+54

    CERN Document Server

    Blay, Pere

    2011-01-01

    The X-ray binary system 4U 2206+54 hides many mysteries. Among them, the surprising behavior of both of its components: the O9.5 dwarf star BD+53$^\\circ$2790 and a slowly rotating neutron star. BD+53$^\\circ$2790 misled the astronomers showing itself very likely as a Be star. However, a deeper spectral analysis and more intense monitoring, revealed that the real picture was a bit more complicated: a) Although it shows evidence of a circumstellar envelope, its observable properties differ from those typical envelopes in Be stars. b) Comparison with spectral standards and models indicates a possible over-abundance in He. This would open the possibility to link the behavior of BD+53$^\\circ$2790 to the He-rich class of stars. c) UV spectra shows an abnormally slow and dense wind for an O9.5V star. d) Spectral classification in the IR wavelength region suggest a more likely supergiant nature of the source, in contradiction with the optical classification. e) The presence of an intense magnetic field is under invest...

  6. A NuSTAR observation of the reflection spectrum of the low mass X-ray binary 4U 1728-34

    CERN Document Server

    Sleator, Clio C; King, Ashley L; Miller, Jon M; Boggs, Steven E; Bachetti, Matteo; Barret, Didier; Chenevez, Jerome; Christensen, Finn E; Craig, William W; Hailey, Charles J; Harrison, Fiona A; Rahoui, Farid; Stern, Daniel K; Walton, Dominic J; Zhang, William W

    2016-01-01

    We report on a simultaneous NuSTAR and Swift observation of the neutron star low-mass X-ray binary 4U 1728-34. We identified and removed four Type I X-ray bursts during the observation in order to study the persistent emission. The continuum spectrum is hard and well described by a black body with kT = 1.5 keV and a cutoff power law with {\\Gamma} = 1.5. Residuals between 6 and 8 keV provide strong evidence of a broad Fe K{\\alpha} line. By modeling the spectrum with a relativistically blurred reflection model, we find an upper limit for the inner disk radius of $R_{\\rm in} \\leq 2R_{\\rm ISCO}$ . Consequently we find that $R_{\\rm NS} \\leq 23$ km, assuming M = 1.4 $\\rm\\,M_{\\mathord\\odot}$ and a = 0.15. We also find an upper limit on the magnetic field of $B \\leq 2\\times 10^8$ G

  7. Iron-line and continuum variations in the XMM-Newton and Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1636-53

    NARCIS (Netherlands)

    Lyu, Ming; Mendez, Mariano; Belloni, Tomaso; Homan, Jeroen; Sanna, Andrea; Hiemstra, Beike

    2014-01-01

    We used six simultaneous XMM-Newton and Rossi X-ray Timing Explorer plus five Suzaku observations to study the continuum spectrum and the iron emission line in the neutron-star low-mass X-ray binary 4U 1636-53 as a function of the position of the source in the colour-colour diagram. We modelled the

  8. Iron-line and continuum variations in the XMM-Newton and Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1636-53

    NARCIS (Netherlands)

    Lyu, Ming; Méndez, Mariano; Sanna, Andrea; Homan, Jeroen; Belloni, Tomaso; Hiemstra, Beike

    2014-01-01

    We used six simultaneous XMM-Newton and Rossi X-ray Timing Explorer plus five Suzaku observations to study the continuum spectrum and the iron emission line in the neutron-star low-mass X-ray binary 4U 1636-53. We modelled the spectra with two thermal components (representing the accretion disc and

  9. Application of the Ghosh & Lamb relation to the spin-up/down behavior in the X-ray binary pulsar 4U 1626-67

    Science.gov (United States)

    Takagi, Toshihiro; Mihara, Tatehiro; Sugizaki, Mutsumi; Makishima, Kazuo; Morii, Mikio

    2016-06-01

    We analyzed continuous Monitor of All-sky X-ray Image/Gas Slit Camera (MAXI/GSC) data of the X-ray binary pulsar 4U 1626-67 from 2009 October to 2013 September, and determined the pulse period and the pulse-period derivative for every 60-d interval by the epoch folding method. The obtained periods are consistent with those provided by the Fermi/Gamma-ray Burst Monitor pulsar project. In all the 60-d intervals, the pulsar was observed to spin up, with the spin-up rate positively correlated with the 2-20 keV flux. We applied the accretion torque model proposed by Ghosh and Lamb (1979, ApJ, 234, 296) to the MAXI/GSC data, as well as the past data including both spin-up and spin-down phases. The "Ghosh & Lamb" relation was confirmed to successfully explain the observed relation between the spin-up/down rate and the flux. By comparing the model-predicted luminosity with the observed flux, the source distance was constrained as 5-13 kpc, which is consistent with that found by Chakrabarty (1998, ApJ, 492, 342). Conversely, if the source distance is assumed, the data can constrain the mass and radius of the neutron star, because the Ghosh & Lamb model depends on these parameters. We attempted this idea, and found that an assumed distance of, e.g., 10 kpc gives a mass in the range of 1.81-1.90 solar mass, and a radius of 11.4-11.5 km, although these results are still subject to considerable systematic uncertainties, other than distance.

  10. High energy characteristics of Neutron star low mass X-ray binaries as seen by INTEGRAL: the 4U 1722-30 case

    CERN Document Server

    Tarana, Antonella; Ubertini, Pietro

    2013-01-01

    We report here results on the long time behaviour of the variable source 4U 1722-30, obtained from INTEGRAL non-continuous observations carried out between 2003 and 2009. During this period 4U 1722-30 shows a general persistent emission along with several bright outbursts resembling those of transient X-ray sources/X-ray novae. However the source never switches into a real quiescent state, with very weak or undetectable flux level, as it normally occurs in transient sources. We compare here flux ratios and spectral state variations measured during the different outbursts and highlight the peculiar character of the 2008 outburst, for which we also propose a specific physical explanation.

  11. Black Hole Mass Determination In the X-Ray Binary 4U 1630-47: Scaling of Spectral and Variability Characteristics

    Science.gov (United States)

    Seifina, Elena; Titarchuk, Lev; Shaposhnikov, Nikolai

    2014-01-01

    We present the results of a comprehensive investigation on the evolution of spectral and timing properties of the Galactic black hole candidate 4U 1630-47 during its spectral transitions. In particular, we show how a scaling of the correlation of the photon index of the Comptonized spectral component gamma with low-frequency quasi-periodic oscillations (QPOs), ?(sub L), and mass accretion rate, M, can be applied to the black hole mass and the inclination angle estimates.We analyze the transition episodes observed with the Rossi X-Ray Timing Explorer and BeppoSAX satellites.We find that the broadband X-ray energy spectra of 4U 1630-47 during all spectral states can be modeled by a combination of a thermal component, a Comptonized component, and a red-skewed iron-line component. We also establish that gamma monotonically increases during transition from the low-hard state to the high-soft state and then saturates for high mass accretion rates. The index saturation levels vary for different transition episodes. Correlations of gamma versus ?(sub L) also show saturation at gamma (is) approximately 3. Gamma -M and gamma -?(sub L) correlations with their index saturation revealed in 4U 1630-47 are similar to those established in a number of other black hole candidates and can be considered as an observational evidence for the presence of a black hole in these sources. The scaling technique, which relies on XTE J1550-564, GRO 1655-40, and H1743-322 as reference sources, allows us to evaluate a black hole mass in 4U 1630-47 yielding M(sub BH) (is) approximately 10 +/- 0.1 solar masses and to constrain the inclination angle of i (is) approximately less than 70 deg.

  12. The properties of cross-correlation and spectra of the low-mass X-ray binary 4U 1608-52

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Ya-Juan; Yuan, Hai-Long; Dong, Yi-Qiao; Zhang, Hao-Tong; Zhang, Cheng-Min; Zhao, Yong-Heng [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Zhang, Shu; Qu, Jin-Lu [Particle Astrophysics Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wang, Ya-Nan; Li, Zhi-Bing, E-mail: leiyjcwmy@163.com [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 150, Science 1-Street, Urumqi, Xinjiang 830011 (China)

    2014-03-01

    With RXTE data, we analyzed the cross-correlation function between the soft and hard X-rays of the transient atoll source 4U 1608-52. We found anti-correlations in three outbursts occurred in 1998, 2002, and 2010, and we found significant time lags of several hundreds of seconds in the latter two outbursts. Our results show no correlation between the soft and hard X-rays in the extreme island state and a dominated positive correlation in the lower banana state. Anti-correlations are presented at the upper banana state for the outburst of 2010 and at the island and the lower left banana states for the other two outbursts. So far for atoll sources, the cross-correlation has been studied statistically only for 4U 1735-44, where anti-correlations showed up in the upper banana state. Here our investigation on 4U 1608-52 provides a similar result in its 2010 outburst. In addition, we notice that the luminosities in the upper banana of the 1998 and 2002 outbursts are about 1.5 times that of the 2010 outburst whose luminosity in the upper banana is close to that of 4U 1735-44. The results suggest that the states in the color-color diagram of a source could be correlated with the luminosity of the source. A further spectral analysis during the 2010 outburst is also shown, which suggests that the disk can be a little truncated in the upper banana. The feature on the upper banana is similar to the previous results of the flaring branch in Z sources.

  13. The properties of cross-correlation and spectra of the low-mass X-ray binary 4U 1608-52

    CERN Document Server

    Lei, Ya-Juan; Qu, Jin-Lu; Zhang, Hao-Tong; Li, Zhi-Bing; Zhang, Cheng-Min; Zhao, Yong-Heng

    2013-01-01

    With {\\it RXTE} data, we analyzed the cross-correlation function between the soft and hard X-rays of the transient atoll source 4U 1608-52. We found anti-correlations in three outbursts occurred in 1998, 2002 and 2010, and significant time lags of several hundreds of seconds in the latter two outbursts. Our results show no correlation between the soft and hard X-rays in the island state, and a dominated positive correlation in the lower banana state. Anti-correlations are presented at the upper banana state for the outburst of 2010 and at the lower left banana states for the other two outbursts. So far for atoll sources the cross-correlation has been studied statistically only for 4U 1735-44, where anti-correlations showed up in the upper banana state. Here our investigation upon 4U 1608-52 provides a similar result in its 2010 outburst. In addition, we notice that the luminosities in the upper banana of 1998 and 2002 outbursts are about 1.5 times that of 2010 outburst whose luminosity in the upper banana is ...

  14. BEPPOSAX and RXTE spectral study of the low-mass X-ray binary 4u~1705-44. Spectral hardening during the banana branch

    CERN Document Server

    Seifina, Elena; Shrader, Chris; Shaposhnikov, Nikolai

    2015-01-01

    We analyze the X-ray spectra of the atoll 4U~1705-44 when the source undergoes the island-banana state transition. We use the Rossi X-ray Timing Explorer (RXTE) and BeppoSAX observations for this analysis. We demonstrate that the broad-band energy spectral distributions for all evolutinary states can be fitted by a model, consisting two Comptonized components. One arises from the seed photons coming from a neutron star (NS) atmosphere at a temperature kT_{s1}80 keV. This phase is similar to that was previously found in the Z-source Sco X-1. We interpret the decreasing index phase using a model in which a super-Eddington radiation pressure from the neutron star causes an expansion of the Compton cloud similar to that found previously in Sco~X-1 during the Flaring branch.

  15. Fourier resolved spectroscopy of 4U 1728-34: New Insights into Spectral and Temporal Properties of Low-Mass X-ray Binaries

    CERN Document Server

    Shrader, C R; Kazanas, D

    2007-01-01

    Using archival RXTE data we derive the 2-16 keV Fourier-resolved spectra of the Atoll source 4U 1728-34 in a sequence of its timing states as its low QPO frequency spans the range between 6 and 94 Hz. The increase in the QPO frequency accompanies a spectral transition of the source from its island to its banana states. The banana-states' Fourier-resolved spectra are well fitted by a single blackbody component with $kT \\sim 2-3$ keV depending on the source position in the color -- color diagram and the Fourier frequency, thus indicating that this spectral component is responsible for the source variability on these timescales. This result is in approximate agreement with similar behavior exhibited by the Z sources, suggesting that, as in that case, the boundary layer -- the likely source of the thermal component -- is supported by radiation pressure. Furthermore, it is found that the iron line at $\\sim$6.6 keV, clearly present in the averaged spectra, not apparent within the limitations of our measurements in ...

  16. RXTE Observations of the Low-Mass X-Ray Binary 4U 1608-522 in Upper-Banana State

    CERN Document Server

    Takahashi, Hiromitsu; Makishima, Kazuo

    2011-01-01

    To investigate the physics of mass accretion onto weakly-magnetized neutron stars, 95 archival RXTE datasets of an atoll source 4U 1608-522, acquired over 1996-2004 in so-called upper-banana state, were analyzed. The object meantime exhibited 3-30 keV luminosity in the range of <~ 10^35 - 4 x 10^37 erg s^-1, assuming a distance of 3.6 kpc. The 3-30 keV PCA spectra, produced one from each dataset, were represented successfully with a combination of a soft and a hard component, of which the presence was revealed in a model-independent manner by studying spectral variations among the observations. The soft component is expressed by so-called multi-color disk model with a temperature of ~1.8 keV, and is attributed to the emission from an optically-thick standard accretion disk. The hard component is a blackbody emission with a temperature of ~2.7 keV, thought to be emitted from the neutron-star surface. As the total luminosity increases, a continuous decrease was observed in the ratio of the blackbody luminosi...

  17. Discovery of a correlation between the frequency of the mHz quasi-periodic oscillations and the neutron-star temperature in the low-mass X-ray binary 4U 1636-53

    CERN Document Server

    Lyu, Ming; Altamirano, Diego

    2014-01-01

    We detected millihertz quasi-periodic oscillations (QPOs) in an XMM-Newton observation of the neutron-star low-mass X-ray binary 4U 1636-53. These QPOs have been interpreted as marginally-stable burning on the neutron-star surface. At the beginning of the observation the QPO was at around 8 mHz, together with a possible second harmonic. About 12 ks into the observation a type I X-ray burst occurred and the QPO disappeared; the QPO reappeared ~25 ks after the burst and it was present until the end of the observation. We divided the observation into four segments to study the evolution of the spectral properties of the source during intervals with and without mHz QPO. We find that the temperature of the neutron-star surface increases from the QPO segment to the non-QPO segment, and vice versa. We also find a strong correlation between the frequency of the mHz QPO and the temperature of a black-body component in the energy spectrum representing the temperature of neutron-star surface. Our results are consistent ...

  18. Iron-line and continuum variations in the XMM-Newton and Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1636-53

    CERN Document Server

    Lyu, Ming; Sanna, Andrea; Homan, Jeroen; Belloni, Tomaso; Hiemstra, Beike

    2014-01-01

    We used six simultaneous XMM-Newton and Rossi X-ray Timing Explorer plus five Suzaku observations to study the continuum spectrum and the iron emission line in the neutron-star low-mass X-ray binary 4U 1636-53. We modelled the spectra with two thermal components (representing the accretion disc and boundary layer), a Comptonised component (representing a hot corona), and either a Gaussian or a relativistic line component to model an iron emission line at about 6.5 keV. For the relativistic line component we used either the diskline, laor or kyrline model, the latter for three different values of the spin parameter. The fitting results for the continuum are consistent with the standard truncated disc scenario. We also find that the flux and equivalent width of the iron line first increase and then decrease as the flux of the Comptonised component increases. This could be explained either by changes in the ionisation state of the accretion disc where the line is produced by reflection, or by light bending of th...

  19. Relation between spectral changes and the presence of the lower kHz QPO in the neutron-star low-mass X-ray binary 4U 1636-53

    CERN Document Server

    Zhang, Guobao; Sanna, Andrea; Ribeiro, Evandro M; Gelfand, Joseph D

    2016-01-01

    We fitted the $3-180$-keV spectrum of all the observations of the neutron-star low-mass X-ray binary 4U 1636$-$53 taken with the {\\it Rossi X-ray Timing Explorer} using a model that includes a thermal Comptonisation component. We found that in the low-hard state the power-law index of this component, $\\Gamma$, gradually increases as the source moves in the colour-colour diagram. When the source undergoes a transition from the hard to the soft state $\\Gamma$ drops abruptly; once the source is in the soft state $\\Gamma$ increases again and then decreases gradually as the source spectrum softens further. The changes in $\\Gamma$, together with changes of the electron temperature, reflect changes of the optical depth in the corona. The lower kilohertz quasi-periodic oscillation (kHz QPO) in this source appears only in observations during the transition from the hard to the soft state, when the optical depth of the corona is high and changes depends strongly upon the position of the source in the colour-colour diag...

  20. Broad-band X-ray emission and the reality of the broad iron line from the neutron star-white dwarf X-ray binary 4U 1820-30

    Science.gov (United States)

    Mondal, Aditya S.; Dewangan, G. C.; Pahari, M.; Misra, R.; Kembhavi, A. K.; Raychaudhuri, B.

    2016-09-01

    Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disc. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here, we investigate the reality of the broad iron line detected earlier from the neutron-star low-mass X-ray binary 4U 1820-30 with a degenerate helium dwarf companion. We perform a comprehensive, systematic broad-band spectral study of the atoll source using Suzaku and simultaneous NuSTAR and Swift observations. We have used different continuum models involving accretion disc emission, thermal blackbody and thermal Comptonization of either disc or blackbody photons. The Suzaku data show positive and negative residuals in the region of Fe K band. These features are well described by two absorption edges at 7.67 ± 0.14 keV and 6.93 ± 0.07 keV or partial covering photoionized absorption or by blurred reflection. Though, the simultaneous Swift and NuSTAR data do not clearly reveal the emission or absorption features, the data are consistent with the presence of either absorption or emission features. Thus, the absorption based models provide an alternative to the broad iron line or reflection model. The absorption features may arise in winds from the inner accretion disc. The broad-band spectra appear to disfavour continuum models in which the blackbody emission from the neutron-star surface provides the seed photons for thermal Comptonization. Our results suggest emission from a thin accretion disc (kTdisc ˜ 1 keV), Comptonization of disc photons in a boundary layer most likely covering a large fraction of the neutron-star surface and innermost parts of the accretion disc, and blackbody emission (kTbb ˜ 2 keV) from the polar regions.

  1. Impact of a Binary System Common Envelope on Mass Transfer through the Inner Lagrange Point

    CERN Document Server

    Bisikalo, D V; Kuznetsov, O A; Chechetkin, V M

    1997-01-01

    Results of numerical simulations of the impact of a common envelope on the matter flow pattern near the outflowing component in a semidetached binary system are presented. Three-dimensional modeling of the matter transfer gas dynamics in a low-mass X-ray binary X1822-371 enable investigation of the structure of flows in the vicinity of the inner Lagrange point L1. Taking into account the common envelope of the system substantially changes the flow pattern near the Roche surface of the outflowing component. In a stationary regime, accretion of common envelope gas is observed over a significant fraction of the donor star's surface, which inhibits the flow of gas along the Roche surface to L1. The change in the flow pattern is particularly significant near L1, where the stream of common envelope gas strips matter off the stellar surface. This, in turn, significantly increases (by an order of magnitude) the gas flow from the donor surface in comparison with the estimates of standard models.

  2. High proper motion X-ray binaries from the Yale Southern Proper Motion Survey

    CERN Document Server

    Maccarone, Thomas J; Casetti-Dinescu, Dana I

    2014-01-01

    We discuss the results of cross-correlating catalogs of bright X-ray binaries with the Yale Southern Proper Motion catalog (version 4.0). Several objects already known to have large proper motions from Hipparcos are recovered. Two additional objects are found which show substantial proper motions, both of which are unusual in their X-ray properties. One is IGR J17544-2619, one of the supergiant fast X-ray transients. Assuming the quoted distances in the literature for this source of about 3 kpc are correct, this system has a peculiar velocity of about 275 km/sec -- greater than the velocity of a Keplerian orbit at its location of the Galaxy, and in line with the expectations formed from suggestions that the supergiant fast X-ray transients should be highly eccentric. We discuss the possibility that these objects may help explain the existence of short gamma-ray bursts outside the central regions of galaxies. The other is the source 2A~1822-371, which is a member of the small class of objects which are low mas...

  3. The fundamental cyclotron line in 4U 1538-52

    CERN Document Server

    Rodes-Roca, J J; Bernabéu, J G

    2009-01-01

    We present pulse phase averaged spectra of the high mass X-ray binary pulsar 4U 1538-52/QV Nor. Observations of this persistent accreting pulsar were made with the Rossi X-ray Timing Explorer (RXTE). We study the variability of cyclotron resonant scattering feature (CRSF or simply cyclotron line) in the high energy spectra of this binary system. We show that the parameters of the CRSF are correlated. The first one is, as suggested by theory, between the width and the energy of the cyclotron line. The second one is between the relative width and the optical depth of the cyclotron line. We discuss these results with studies of other X-ray pulsars and their implications on the line variability.

  4. 4U 1909+07: a Hidden Pearl

    Science.gov (United States)

    Kreykenbohm, I.; Fürst, F.; Barrágan, L.; Wilms, J.; Rothschild, R. E.; Suchy, S.; Pottschmidt, K.

    We present a detailed spectral and timing analysis of the High Mass X-ray Binary (HMXB) 4U 1909+07 with INTEGRAL and RXTE. 4U1909+07 is a persistent accreting X-ray pulsar with a period of approximately 605 s. The period changes erratically consistent with a random walk expected for a wind accreting system. INTEGRAL detects the source with an average of 2.4 cps (corresponding to 15mCrab), but sometimes exhibits flaring activity up to 50 cps (i.e. 300mCrab). The strongly energy dependent pulse profile shows a double peaked structure at low energies and only a single narrow peak at energies above 20 keV. The phase averaged spectrum is well described by a powerlaw modified at higher energies by an exponential cutoff and photoelectric absorption at low energies. In addition at 6.4 keV a strong iron fluorescence line and at lower energies a blackbody component are present. We performed phase resolved spectroscopy to study the pulse phase dependence of the spectral parameters: while most spectral parameters are constant within uncertainties, the blackbody normalization and the cutoff folding energy vary strongly with phase.

  5. 4U 1909+07: a Hidden Pearl

    Directory of Open Access Journals (Sweden)

    I. Kreykenbohm

    2011-01-01

    Full Text Available We present a detailed spectral and timing analysis of the High Mass X-ray Binary (HMXB 4U 1909+07 with INTEGRAL and RXTE. 4U1909+07 is a persistent accreting X-ray pulsar with a period of approximately 605 s. The period changes erratically consistent with a random walk expected for a wind accreting system. INTEGRAL detects the source with an average of 2.4 cps (corresponding to 15mCrab, but sometimes exhibits flaring activity up to 50 cps (i.e. 300mCrab. The strongly energy dependent pulse profile shows a double peaked structure at low energies and only a single narrow peak at energies above 20 keV. The phase averaged spectrum is well described by a powerlaw modified at higher energies by an exponential cutoff and photoelectric absorption at low energies. In addition at 6.4 keV a strong iron fluorescence line and at lower energies a blackbody component are present. We performed phase resolved spectroscopy to study the pulse phase dependence of the spectral parameters: while most spectral parameters are constant within uncertainties, the blackbody normalization and the cutoff folding energy vary strongly with phase.

  6. 4U 1909+07: a well-hidden pearl

    CERN Document Server

    Fuerst, F; Suchy, S; Barragan, L; Wilms, J; Rothschild, R E; Pottschmidt, K

    2010-01-01

    We present the first detailed spectral and timing analysis of the High Mass X-ray Binary (HMXB) 4U 1909+07 with INTEGRAL and RXTE. 4U 1909+07 is detected in the ISGRI 20-40 keV energy band with an average countrate of 2.6 cps. The pulse period of ~604 sec is not stable, but changing erratically on timescales of years. The pulse profile is strongly energy dependent: it shows a double peaked structure at low energies, the secondary pulse decreases rapidly with increasing energy and above 20 keV only the primary pulse is visible. This evolution is consistent between PCA, HEXTE, and ISGRI. The phase averaged spectrum can be well described by the sum of a photoabsorbed power law with a cutoff at high energies and a blackbody component. To investigate the pulse profile, we performed phase resolved spectral analysis. We find that the changing spectrum can be best described with a variation of the folding energy. We rule out a correlation between the black body component and the continuum variation and discuss possib...

  7. The First Suzaku Observation of 4U 1532-522

    Science.gov (United States)

    Rothschild, Richard

    Observations of neutron star pulsars in binary systems with a massive main sequence star provide us with important information about the physical processes in the wind of the massive star, the coupling between the wind material and the strong magnetic field of the neutron star, and the physics present in the region just above the magnetic poles. The goal of this proposal is to better understand the physical processes and geometry of the 4U1538-522/QV Nor system through precision spectroscopy with the Japanese X-ray satellite Suzaku on several timescales, comparison to earlier results, and in-depth analysis of RXTE observations. The analysis of the Suzaku observation is of prime importance due to the excellent performance of the instruments aboard. While reanalysis of the RXTE data is a secondary goal, it remains important for placing the Suzaku observation in context of the orbital phase and history of the binary system. Similarly, comparison to the low energy results from XMM-Newton, Chandra, and BeppoSAX X-ray missions is a secondary goal that can yield significant insight into the system. We request funding to analyze our successful Suzaku proposal, since no funding is available from the project. This investigation addresses the Astrophysics Strategic Science Goal To discover how the universe works and to explore how the universe evolves, the Science Question How do matter, energy, space, and time behave under the extraordinarily diverse conditions of the cosmos, and the Science Objective to understand the origin and destiny of the universe and the nature of black holes, dark energy, dark matter, and gravity.

  8. Phase Dependent Spectral Variability of 4U1907+09

    CERN Document Server

    Roberts, M S E; Leahy, D A; Hall, T A; Finley, J P; Cominsky, L R; Srinivasan, R; Roberts, Mallory S.E.; Michelson, Peter F.; Leahy, Denis A.; Hall, Tony A.; Finley, John P.; Cominsky, Lynn R.; Srinivasen, Radhika

    2001-01-01

    We report on ASCA, RXTE, and archival observations of the high mass X-ray binary pulsar 4U1907+09. Spectral measurements of the absorption and flux were made at all phases of the X-ray pulsar orbit, including the first spectral measurements of an extended period of low flux during two of the ASCA observations. We find that a simple spherical wind model can fit the time averaged light curve as measured by the RXTE ASM, but does not fit the observed changes in the absorption column or account for the existence of the phase-locked secondary flare. An additional model component consisting of a trailing stream can account for the variations in column depth. However, these models favor a high inclination angle for the system, suggesting a companion mass more consistent with an identification as a Be-star. In this case an equatorially enhanced wind and inclined neutron star orbit may be a more appropriate interpretation of the data.

  9. Spectral states evolution of 4U 1728-34 observed by INTEGRAL and RXTE : non-thermal component detection

    NARCIS (Netherlands)

    Tarana, A.; Belloni, T.; Bazzano, A.; Mendez, M.; Ubertini, P.

    2011-01-01

    We report results of a one-year monitoring of the low-mass X-ray binary (LMXB) source (atoll type) 4U 1728-34 with INTEGRAL and RXTE. Three time intervals were covered by INTEGRAL, during which the source showed strong spectral evolution. We studied the broad-band X-ray spectra in detail by fitting

  10. Broad iron line in the fast spinning neutron-star system system 4U 1636-53

    NARCIS (Netherlands)

    Sanna, Andrea; Hiemstra, Beike; M´endez, Mariano; Altamirano, Diego; Belloni, Tomaso; Linares, Manuel

    2013-01-01

    We analysed the X-ray spectra of six observations, simultaneously taken with XMMNewton and Rossi X-ray Timing Explorer (RXTE), of the neutron star low-mass X-ray binary 4U 1636–53. The observations cover several states of the source, and therefore a large range of inferred mass accretion rate. These

  11. The Steady Spin-down Rate of 4U 1907+09

    Science.gov (United States)

    Baykal, Altan; Inam, Cagdas; Alpar, M. Ali; intZhand, Jean; Strohmayer, Tod; White, Nicholas E. (Technical Monitor)

    2001-01-01

    Using X-ray data from the Rossi X-ray Timing Explorer, we report the pulse timing results of the accretion-powered, high-mass X-ray binary pulsar 4UU 1907+09, covering a time-span of almost two years. We measured three new pulse periods in addition to the previously measured four pulse periods. We are able to connect pulse arrival times in phase for more than a year. The source has been spinning down almost at a constant rate, with a spin-down rate of v = (- 3.54 +/- 0.02) x 10(exp -14) Hz s(exp -1) for more than 15 yr. Residuals of pulse arrival times yield a very low level of random-walk noise, with a strength of approximately 2 x 10(exp -20) rad(exp 2) s(exp -3) on a time-scale of 383 d, which is 40 times lower than that of the high-mass X-ray binary pulsar Vela X-1. The noise strength is only a factor of five greater than that of the low-mass X-ray binary pulsar 4U 1626-67. The low level of the timing noise and the very stable spin-down rate of 4U 1907+09 make this source unique among the high-mass X-ray binary pulsars, providing another example, in addition to 4U 1626-67, of long-term quiet spin down from an accruing source. These examples show that the extended quiet spin-down episodes observed in the anomalous X-ray pulsars 1RXS J170849.0-400910 and 1E 2259+586 do not necessarily imply that these sources are not accreting pulsars.

  12. Unveiling 4U2206+54 Using Simultaneous RXTE and Optical Observations

    Science.gov (United States)

    Wilms, Joern

    We propose a 200ksec long RXTE observation of the putative Be binary 4U2206+54 to confirm the presence of a cyclotron line feature at 30keV. The confirmation of this line would allow us to determine the nature of the compact object as a neutron star, making 4U2206+54 the first cyclotron line source without X-ray pulsations. Simultaneous optical observations will furthermore allow us to shed light on the accretion process in this system, which has one of the strangest optical spectra of all Be-like systems. By studying one of the end stages of stellar evolution, this program contributes to NASA's Strategic Objectives for 2005 and Beyond: ``Explore the Universe to understand its origin, structure, evolution and destiny''.

  13. X-ray burst induced spectral variability in 4U 1728-34

    CERN Document Server

    Kajava, J J E; Kuulkers, E; Poutanen, J

    2016-01-01

    Aims. INTEGRAL has been monitoring the Galactic center region for more than a decade. Over this time INTEGRAL has detected hundreds of type-I X-ray bursts from the neutron star low-mass X-ray binary 4U 1728-34, a.k.a. "the slow burster". Our aim is to study the connection between the persistent X-ray spectra and the X-ray burst spectra in a broad spectral range. Methods. We performed spectral modeling of the persistent emission and the X-ray burst emission of 4U 1728-34 using data from the INTEGRAL JEM-X and IBIS/ISGRI instruments. Results. We constructed a hardness intensity diagram to track spectral state variations. In the soft state the energy spectra are characterized by two thermal components - likely from the accretion disc and the boundary/spreading layer - together with a weak hard X-ray tail that we detect in 4U 1728-34 for the first time in the 40 to 80 keV range. In the hard state the source is detected up to 200 keV and the spectrum can be described by a thermal Comptonization model plus an addit...

  14. Orbital phase resolved spectroscopy of 4U1538-52 with MAXI

    CERN Document Server

    Rodes-Roca, J J; Nakahira, S; Torrejón, J M; Giménez-García, Á; Bernabéu, G

    2015-01-01

    4U 1538-52, an absorbed high mass X-ray binary with an orbital period of 3.73 days, shows moderate orbital intensity modulations with a low level of counts during the eclipse. Several models have been proposed to explain the accretion at different orbital phases by a spherically symmetric stellar wind from the companion. The aim of this work is to study both the light curve and orbital phase spectroscopy of this source in the long term. Particularly, the folded light curve and the changes of the spectral parameters with orbital phase to analyse the stellar wind of QV Nor, the mass donor of this binary system. We used all the observations made from the Gas Slit Camera on board MAXI of 4U 1538-52 covering many orbits continuously. We obtained the good interval times for every orbital phase range which were the input to extract our data. We estimated the orbital period of the system and then folded the light curves and we fitted the X-ray spectra with the same model for every orbital phase spectrum. We also extr...

  15. The cooling phase of Type I X-ray bursts observed with RXTE in 4U 1820–30 does not follow the canonical F / T4 relation

    NARCIS (Netherlands)

    Garc´ıa, Federico; Zhan, Guobao; M´endez, Mariano

    2013-01-01

    We analysed the complete set of bursts from the neutron-star low-mass X-ray binary 4U 1820–30 detected with the Rossi X-ray Timing Explorer (RXTE). We found that all are photospheric radius expansion bursts, and have similar duration, peak flux and fluence. From the analysis of time-resolved spectra

  16. Recent Timing Studies on RXTE Observations of 4U 1538-52

    CERN Document Server

    Baykal, A; Beklen, E

    2005-01-01

    The high mass X-ray binary pulsar 4U 1538-52 was observed between July 31- August 7, 2003. Using these archival observations, we determined the new orbital epochs for both circular and elliptical orbit models given by Clark (2000). Orbital epochs for both orbit solutions agreed each other and showed that orbital period is constant with $\\dot{P} / P = (0.4 \\pm 1.8) \\times 10^{-6} yr^{-1}$. Our results are in agreement with those of Clark (2000), in 1 $\\sigma $ level however give only upper limit for evidence of orbital decay. Determination of pulse frequency showed that the source is still spinning up on average spin up rate $2.76 \\times 10^{-14} Hz^{-1}$ since BATSE observations reported by Rubin et al., (1997).

  17. X-ray burst-induced spectral variability in 4U 1728-34

    Science.gov (United States)

    Kajava, J. J. E.; Sánchez-Fernández, C.; Kuulkers, E.; Poutanen, J.

    2017-03-01

    Aims: INTEGRAL has been monitoring the Galactic center region for more than a decade. Over this time it has detected hundreds of type-I X-ray bursts from the neutron star low-mass X-ray binary 4U 1728-34, also known as the slow burster. Our aim is to study the connection between the persistent X-ray spectra and the X-ray burst spectra in a broad spectral range. Methods: We performed spectral modeling of the persistent emission and the X-ray burst emission of 4U 1728-34 using data from the INTEGRAL JEM-X and IBIS/ISGRI instruments. Results: We constructed a hardness intensity diagram to track spectral state variations. In the soft state, the energy spectra are characterized by two thermal components likely coming from the accretion disc and the boundary/spreading layer, together with a weak hard X-ray tail that we detect in 4U 1728-34 for the first time in the 40 to 80 keV range. In the hard state, the source is detected up to 200 keV and the spectrum can be described by a thermal Comptonization model plus an additional component: either a powerlaw tail or reflection. By stacking 123 X-ray bursts in the hard state, we detect emission up to 80 keV during the X-ray bursts. We find that during the bursts the emission above 40 keV decreases by a factor of approximately three with respect to the persistent emission level. Conclusions: Our results suggest that the enhanced X-ray burst emission changes the spectral properties of the accretion disc in the hard state. The likely cause is an X-ray burst induced cooling of the electrons in the inner hot flow near the neutron star.

  18. Study of the reflection spectrum of the LMXB 4U 1702-429

    CERN Document Server

    Iaria, R; Del Santo, M; Pintore, F; Sanna, A; Papitto, A; Burderi, L; Riggio, A; Gambino, A F; Matranga, M

    2016-01-01

    The source 4U 1702-429 (Ara X-1) is a low-mass X-ray binary system hosting a neutron star. Albeit the source is quite bright ( $\\sim10^{37}$ erg s$^{-1}$) its broadband spectrum has never been studied. Neither dips nor eclipses have been observed in the light curve suggesting that its inclination angle is smaller than 60$^{\\circ}$.We analysed the broadband spectrum of 4U 1702-429 in the 0.3-60 keV energy range, using XMM-Newton and INTEGRAL data, to constrain its Compton reflection component if it is present. After excluding the three time intervals in which three type-I X-ray bursts occurred, we fitted the joint XMM-Newton and INTEGRAL spectra obtained from simultaneous observations. A broad emission line at 6.7 keV and two absorption edges at 0.87 and 8.82 keV were detected. We found that a self-consistent reflection model fits the 0.3-60 keV spectrum well. The broadband continuum is composed of an emission component originating from the inner region of the accretion disc, a Comptonised direct emission comi...

  19. Simultaneous optical and X-ray bursts from 4U/MXB 1636-53

    Science.gov (United States)

    Pedersen, H.; Lub, J.; Inoue, H.; Koyama, K.; Makishima, K.; Matsuoka, M.; Mitsuda, K.; Murakami, T.; Oda, M.; Ogawara, Y.

    1982-01-01

    Methods of obtaining information about the geometry of X-ray burster systems from simultaneous optical and X-ray observations are discussed, and such simultaneous observations of 4U/MXB 1636-53 are reported. The physical idea of an optical burst being due to reprocessing of an X-ray burst in material in the vicinity of the compact object is discussed. The resulting modification of the X-ray burst signal is described in terms of an optical response function. Delay and smearing due to radiative processes are discussed along with those due to the geometry. For 4U/MXB 1636-53, the estimated delay is 2.5 seconds, the smearing is less than four seconds, and the maximum temperature of the reprocessing region is about 75,000 K. The projected area of the reprocessing region is about 6 x 10 to the 21st square cm. The neutron star is about 1.4 solar masses, the radius of the accretion disk is greater than 1.5 lt-sec, and the mass of the Roche lobe filling companion star is less than 2.0 solar masses, corresponding to a binary period between about one and ten hours.

  20. Discovery of KiloHertz Quasi-Periodic Oscillations in 4U 1735-44

    CERN Document Server

    Wijnands, R; Méndez, M; Van Paradijs, J; Lewin, W H G; Lamb, F K; Vaughan, B; Kuulkers, E; Wijnands, Rudy; Klis, Michiel van der; Mendez, Mariano; Paradijs, Jan van; Lewin, Walter H.G.; Lamb, Frederick K.; Vaughan, Brian; Kuulkers, Erik

    1998-01-01

    We discovered a single kHz quasi-periodic oscillation (QPO) near 1150 Hz in the Rossi X-ray Timing Explorer X-ray light curve of the low mass X-ray binary and atoll source 4U 1735-44. The rms amplitude of this peak was 2-3%, and the FWHM 6-40 Hz. There are indications that the kHz QPO frequency decreased from 1160 Hz to 1145 Hz when the count rate increased, which would be quite different from what is observed in other atoll sources for which kHz QPOs have been discovered. In the X-ray color-color diagram and hardness-intensity diagram the source traced out the curved branch (the so-called banana branch) which has been found by previous instruments. The kHz QPO was only detected when the source was at the lowest count rates during our observations, i.e. on the lower part of the banana branch. When 4U 1735-44 was at higher count rates, i.e. on the upper part of the banana branch and at higher inferred mass accretion rate with respect to that on the lower part of the banana branch, the QPO was not detected. Bes...

  1. Orbital evolution and search for eccentricity and apsidal motion in the eclipsing HMXB 4U 1700-37

    Science.gov (United States)

    Islam, Nazma; Paul, Biswajit

    2016-09-01

    In the absence of detectable pulsations in the eclipsing high-mass X-ray binary 4U 1700-37, the orbital period decay is necessarily determined from the eclipse timing measurements. We have used the earlier reported mid-eclipse time measurements of 4U 1700-37 together with the new measurements from long-term light curves obtained with the all sky monitors RXTE-ASM, Swift-BAT and MAXI-GSC, as well as observations with RXTE-PCA, to measure the long-term orbital evolution of the binary. The orbital period decay rate of the system is estimated to be {dot{P}}/P = -(4.7 ± 1.9) × 10^{-7} yr-1, smaller compared to its previous estimates. We have also used the mid-eclipse times and the eclipse duration measurements obtained from 10-years-long X-ray light curve with Swift-BAT to separately put constraints on the eccentricity of the binary system and attempted to measure any apsidal motion. For an apsidal motion rate greater than 5 deg yr-1, the eccentricity is found to be less than 0.008, which limits our ability to determine the apsidal motion rate from the current data. We discuss the discrepancy of the current limit of eccentricity with the earlier reported values from radial velocity measurements of the companion star.

  2. Orbital evolution and search for eccentricity and apsidal motion in the eclipsing HMXB 4U 1700-37

    CERN Document Server

    Islam, Nazma

    2016-01-01

    In the absence of detectable pulsations in the eclipsing High Mass X-ray binary 4U 1700-37, the orbital period decay is necessarily determined from the eclipse timing measurements. We have used the earlier reported mid-eclipse time measurements of 4U 1700-37 together with the new measurements from long term light curves obtained with the all sky monitors RXTE-ASM, Swift-BAT and MAXI-GSC, as well as observations with RXTE-PCA, to measure the long term orbital evolution of the binary. The orbital period decay rate of the system is estimated to be ${\\dot{P}}/P = -(4.7 \\pm 1.9) \\times 10^{-7}$ yr$^{-1}$, smaller compared to its previous estimates. We have also used the mid-eclipse times and the eclipse duration measurements obtained from 10 years long X-ray light-curve with Swift-BAT to separately put constraints on the eccentricity of the binary system and attempted to measure any apsidal motion. For an apsidal motion rate greater than 5 degrees per year, the eccentricity is found to be less than 0.008, which li...

  3. Suzaku spectroscopy of the neutron star transient 4U 1608-52 during its outburst decay.

    Science.gov (United States)

    Armas Padilla, M.; Ueda, Y.; Hori, T.; Shidatsu, M.; Muñoz-Darias, T.

    2017-01-01

    We test the proposed 3-component spectral model for neutron star low mass X-ray binaries using broad-band X-ray data. We have analysed 4 X-ray spectra (0.8-30 keV) obtained with Suzaku during the 2010 outburst of 4U 1608-52, which have allowed us to perform a comprehensive spectral study covering all the classical spectral states. We use a thermally Comptonized continuum component to account for the hard emission, as well as two thermal components to constrain the accretion disc and neutron star surface contributions. We find that the proposed combination of multicolor disc, single-temperature black body and Comptonization components successfully reproduces the data from soft to hard states. In the soft state, our study supports the neutron star surface (or boundary layer) as the dominant source for the Comptonization seed photons yielding the observed weak hard emission, while in the hard state both solutions, either the disc or the neutron star surface, are equally favoured. The obtained spectral parameters as well as the spectral/timing correlations are comparable to those observed in accreting black holes, which support the idea that black hole and neutron star low mass X-ray binaries undergo a similar state evolution during their accretion episodes.

  4. Is 4U 0114+65 an eclipsing HMXB?

    CERN Document Server

    Pradhan, P; Paul, B C; Bozzo, E; Belloni, T

    2015-01-01

    We present the pulsation and spectral characteristics of the HMXB 4U 0114+65 during a \\emph{Suzaku} observation covering the part of the orbit that included the previously known low intensity emission of the source (dip) and the egress from this state. This dip has been interpreted in previous works as an X-ray eclipse. Notably, in this Suzaku observation, the count rate during and outside the dip vary by a factor of only 2-4 at odds with the eclipses of other HMXBs, where the intensity drops upto two orders of magnitude. The orbital intensity profile of 4U 0114+65 is characterized by a narrow dip in the RXTE-ASM (2-12 \\rm{keV}) light curve and a shallower one in the Swift-BAT (15-50 \\rm{keV}), which is different from eclipse ingress/egress behaviour of other HMXBs. The time-resolved spectral analysis reveal moderate absorption column density (N$_{H}$ - 2-20 $\\times$ $10^{22}$ atoms $cm^{-2}$) and a relatively low equivalent width ($\\sim$ 30 \\rm{eV} \\& 12 \\rm{eV} of the iron K$_\\alpha$ and K$_\\beta$ lines...

  5. SPECTRAL STATE EVOLUTION OF 4U 1820-30: THE STABILITY OF THE SPECTRAL INDEX OF THE COMPTONIZATION TAIL

    Energy Technology Data Exchange (ETDEWEB)

    Titarchuk, Lev; Frontera, Filippo [Dipartimento di Fisica, Universita di Ferrara, Via Saragat 1, I-44122 Ferrara (Italy); Seifina, Elena, E-mail: titarchuk@fe.infn.it, E-mail: lev@milkyway.gsfc.nasa.gov, E-mail: frontera@fe.infn.it, E-mail: seif@sai.msu.ru [Moscow M.V. Lomonosov State University/Sternberg Astronomical Institute, Universitetsky Prospect 13, Moscow 119992 (Russian Federation)

    2013-04-20

    We analyze the X-ray spectra and their timing properties of the compact X-ray binary 4U 1820-30. We establish spectral transitions in this source seen with BeppoSAX and the Rossi X-ray Timing Explorer (RXTE). During the RXTE observations (1996-2009), the source was in the soft state approximately {approx}75% of the time making the lower banana and upper banana transitions combined with long-term low-high state transitions. We reveal that all of the X-ray spectra of 4U 1820-30 are fit by a combination of a thermal (Blackbody) component, a Comptonization component (COMPTB), and a Gaussian-line component. Thus, using this spectral analysis, we find that the photon power-law index {Gamma} of the Comptonization component is almost unchangeable ({Gamma} {approx} 2), while the electron temperature kT{sub e} changes from 2.9 to 21 keV during these spectral events. We also establish that for these spectral events the normalization of the COMPTB component (which is proportional to the mass accretion rate M-dot ) increases by a factor of eight when kT{sub e} decreases from 21 keV to 2.9 keV. Previously, this index stability effect was also found analyzing X-ray data for the Z-source GX 340+0 and for the atolls 4U 1728-34 and GX 3+1. Thus, we can suggest that this spectral stability property is a spectral signature of an accreting neutron star source. On the other hand, in a black hole binary {Gamma} monotonically increases with M-dot and ultimately its value saturates at large M-dot .

  6. Evolution of Spin and Superorbital Modulation in 4U 0114+650

    Science.gov (United States)

    Hu, Chin-Ping; Ng, Chi-Yung; Chou, Yi

    2016-09-01

    We report on a systematic analysis of the spin and superorbital modulations of the high-mass X-ray binary 4U 0114+650, which consists of the slowest spinning neutron star known. Utilizing dynamic power spectra, we found that the spin period varied dramatically during the RXTE ASM and Swift BAT observations. This variation consists of a long-term spin-up trend, and two ~1,000 day and one ~600 day random walk epochs previously, MJD 51,000, ~MJD 51,400-52,000, and ~MJD 55,100-56,100. We further found that the events appear together with depressions of superorbital modulation amplitude. This provides evidence of the existence of an accretion disk, although the physical mechanism of superorbital modulation remains unclear. Furthermore, the decrease of the superorbital modulation amplitude may be associated with the decrease of mass accretion rate from the disk, and may distribute the accretion torque of the neutron star randomly in time.

  7. Variations in the Cyclotron Resonant Scattering Features during 2011 outburst of 4U 0115+63

    CERN Document Server

    Iyer, N; Dewangan, G C; Bhattacharya, D; Seetha, S

    2015-01-01

    We study the variations in the Cyclotron Resonant Scattering Feature (CRSF) during 2011 outburst of the high mass X-ray binary 4U 0115+63 using observations performed with Suzaku, RXTE, Swift and INTEGRAL satellites. The wide-band spectral data with low energy coverage allowed us to characterize the broadband continuum and detect the CRSFs. We find that the broadband continuum is adequately described by a combination of a low temperature (kT ~ 0.8 keV) blackbody and a power-law with high energy cutoff (Ecut ~ 5.4 keV) without the need for a broad Gaussian at ~ 10 keV as used in some earlier studies. Though winds from the companion can affect the emission from the neutron star at low energies (< 3 keV), the blackbody component shows a significant presence in our continuum model. We report evidence for the possible presence of two independent sets of CRSF lines with fundamentals at ~ 11 keV and ~ 15 keV. These two sets of CRSF lines could arise from spatially distinct emitting regions. We also find evidence ...

  8. The time derivative of the kilohertz quasi-periodic oscillations in 4U 1636-53

    CERN Document Server

    Sanna, Andrea; Belloni, Tomaso; Altamirano, Diego

    2012-01-01

    We analysed all archival RXTE observations of the neutron-star low-mass X-ray binary 4U 1636-53 up to May 2010. In 528 out of 1280 observations we detected kilohertz quasi-periodic oscillations (kHz QPOs), with ~ 65% of these detections corresponding to the so-called lower kHz QPO. Using this QPO we measured, for the first time, the rate at which the QPO frequency changes as a function of QPO frequency. For this we used the spread of the QPO frequency over groups of 10 consecutive measurements, sampling timescales between 320 and 1600 s, and the time derivative of the QPO frequency over timescales of 32 to 160 s. We found that: (i) Both the QPO-frequency spread and the QPO time derivative decrease by a factor ~ 3 as the QPO frequency increases. (ii) The average value of the QPO time derivative decreases by a factor of ~ 2 as the timescale over which the derivative is measured increases from less than 64 s to 160 s. (iii) The relation between the absolute value of the QPO time derivative and the QPO frequency ...

  9. Broad iron line in the fast spinning neutron-star system 4U 1636-53

    CERN Document Server

    Sanna, Andrea; Mendez, Mariano; Altamirano, Diego; Belloni, Tomaso; Linares, Manuel

    2013-01-01

    We analysed the X-ray spectra of six observations, simultaneously taken with XMM-Newton and Rossi X-ray Timing Explorer (RXTE), of the neutron star low-mass X-ray binary 4U 1636-53. The observations cover several states of the source, and therefore a large range of inferred mass accretion rate. These six observations show a broad emission line in the spectrum at around 6.5 keV, likely due to iron. We fitted this line with a set of phenomenological models of a relativistically broadened line, plus a model that accounts for relativistically smeared and ionised reflection from the accretion disc. The latter model includes the incident emission from both the neutron-star surface or boundary layer and the corona that is responsible for the high-energy emission in these systems. From the fits with the reflection model we found that in four out of the six observations the main contribution to the reflected spectrum comes from the neutron-star surface or boundary layer, whereas in the other two observations the main ...

  10. BeppoSAX and XMM-Newton spectral study of 4U 1735-44

    CERN Document Server

    Mück, Benjamin; Santangelo, Andrea

    2013-01-01

    Low-mass X-ray binary systems consist of a neutron star and a main-sequence companion star. The compact object accretes matter via Roche-lobe overflow, which leads to an accretion disk. In addition to a broad-band continuum emission of a thermal component and a Comptonization part, evidence for a broad iron K{\\alpha} line is found in several sources. Some of them show an asymmetric line profile as well, which could originate from relativistic effects. To understand the spectral behavior of the system 4U 1735-44, we study the broad-band spectrum and especially the iron line feature between 6.4 and 6.97 keV. The shape of the line allows one to determine the region where the line is produced. Together with the continuum models, a geometrical model of the source can be proposed. Furthermore, the effects of pile-up in the XMM-Newton observation are investigated. We analyzed data obtained with the X-ray satellites BeppoSAX and XMM-Newton. The XMM-Newton data were analyzed, specifically taking into account pile-up e...

  11. An optical counterpart to the anomalous X-ray pulsar 4U0142+61.

    Science.gov (United States)

    Hulleman, F; van Kerkwijk, M H; Kulkarni, S R

    2000-12-01

    The energy source of the anomalous X-ray pulsars (AXPs) is not understood, hence their designation as anomalous. Unlike binary X-ray pulsars, no companions are seen, so the energy cannot be supplied by accretion of matter from a companion star. The loss of rotational energy, which powers radio pulsars, is insufficient to power AXPs. Two models are generally considered: accretion from a large disk left over from the birth process, or decay of a very strong magnetic field (10(15) G) associated with a 'magnetar'. The lack of counterparts at other wavelengths has hampered progress in our understanding of these objects. Here we report deep optical observations of the field around 4U0142+61, which is the brightest AXP in X-rays. The source has no associated supernova remnant, which, together with its spin-down timescale of approximately 10(5) yr (ref. 5), suggests that it may be relatively old. We find an object with peculiar optical colours at the position of the X-ray source, and argue that it is the optical counterpart. The optical emission is too faint to admit the presence of a large accretion disk, but may be consistent with magnetospheric emission from a magnetar.

  12. Fourier resolved spectroscopy of 4U 1543-47 during the 2002 outburst

    Science.gov (United States)

    Reig, P.; Papadakis, I. E.; Shrader, C. R.; Kazanas, D.

    2006-01-01

    We have obtained Fourier-resolved spectra of the black-hole binary 4U 1543-47 in the canonical states (high/soft, very high, intermediate and low/hard) observed in this source during the decay of an outburst that took place in 2002. Our objective is to investigate the variability of the spectral components generally used to describe the energy spectra of black-hole systems, namely a disk component, a power-law component attributed to Comptonization by a hot corona and the contribution of the iron line due to reprocessing of the high energy (E greater than or approx, equal to 7 keV) radiation. We find that i) the disk component is not variable on time scales shorter than approx. 100 seconds, ii) the reprocessing emission as manifest by the variability of the Fe K(alpha) line responds to the primary radiation variations down to time scales of approx. 70 ms in the high and very-high states, but longer than 2 s in the low state, iii) the low-frequency QPOs are associated with variations of the X-ray power law spectral component and not to the disk component and iv) the spectra corresponding to the highest Fourier frequency are the hardest (show the flatter spectra) at a given spectral state. These results questions the models that explain the observed power spectra as due to modulations of the accretion rate only.

  13. A Characterization of the Brightness Oscillations During Thermonuclear Bursts From 4U 1636-536

    CERN Document Server

    Miller, M C

    1999-01-01

    The discovery of nearly coherent brightness oscillations during thermonuclear X-ray bursts from six neutron-star low-mass X-ray binaries has opened up a new way to study the propagation of thermonuclear burning, and may ultimately lead to greater understanding of thermonuclear propagation in other astrophysical contexts, such as in Type Ia supernovae. Here we report detailed analyses of the ~580 Hz brightness oscillations during bursts from 4U 1636-536. We investigate the bursts as a whole and, in more detail, the initial portions of the bursts. We analyze the ~580 Hz oscillations in the initial 0.75 seconds of the five bursts that were used in a previous search for a brightness oscillation at the expected ~290 Hz spin frequency, and find that if the same frequency model describes all five bursts there is insufficient data to require more than a constant frequency or, possibly, a frequency plus a frequency derivative. Therefore, although it is appropriate to use an arbitrarily complicated model of the ~580 Hz...

  14. Sidebands Due to Quasi-periodic Oscillations in 4U 1626-67

    CERN Document Server

    Kommers, J M; Lewin, W H G

    1998-01-01

    The low-mass X-ray binary pulsar 4U 1626-67 shows 0.048 Hz quasi-periodic oscillations (QPOs) and red noise variability as well as coherent pulsations at the 0.130 Hz neutron star spin frequency. Power density spectra of observations made with the Rossi X-ray Timing Explorer show significant sidebands separated from the pulsar spin frequency (and its harmonics) by the QPO frequency. These show that the instantaneous amplitude of the coherent pulsations is modulated by the amplitude of the QPOs. This phenomenon is expected in models such as the magnetospheric beat frequency model where the QPOs originate near the polar caps of the neutron star. In the 4--8 keV energy range, however, the lower-frequency sidebands are significantly stronger than their higher-frequency complements; this is inconsistent with the magnetospheric beat frequency model. We suggest that the 0.048 Hz QPOs are instead produced by a structure orbiting the neutron star at the QPO frequency. This structure crosses the line of sight once per ...

  15. XMM-Newton observations reveal the disappearance of the wind in 4U 1630-47

    CERN Document Server

    Trigo, M Díaz; Miller-Jones, J C A; Guainazzi, M

    2014-01-01

    We report on XMM-Newton observations of the black hole X-ray binary 4U 1630-47 during its 2012-2013 outburst. The first five observations monitor the source as its luminosity increases across the high-soft state of accretion. In the sixth observation the source has made a transition to an "anomalous" state, characterised by a significant contribution of electron scattering. A thermally/radiatively driven disc wind is present in the first four observations, which becomes more photoionised as the luminosity increases with time. In the fifth observation, the wind is not observed any more as a consequence of strong photoionisation and the low sensitivity of this observation. This overall trend is then consistent with a fully ionised wind causing the electron scattering characteristic of the anomalous state in the sixth observation. A broad iron emission line co-exists with the absorption features from the wind in the first four observations but is not visible in the last two observations. We find that the changes...

  16. A long-term optical - X-ray correlation in 4U 1957+11

    CERN Document Server

    Russell, D M; Roche, P; Clark, J S; Breedt, E; Fender, R P

    2009-01-01

    [abridged] Three years of optical monitoring of the low-mass X-ray binary (LMXB) 4U 1957+11 is presented. The source was observed in V, R and i-bands using the Faulkes Telescopes North and South. The light curve is dominated by long-term variations which are correlated (at the > 3 sigma level) with the RXTE ASM soft X-ray flux. The variations span one magnitude in all three filters. We find no evidence for periodicities in our light curves, contrary to a previous short-timescale optical study in which the flux varied on a 9.3-hour sinusoidal period by a smaller amplitude. The optical spectral energy distribution is blue and typical of LMXBs in outburst, as is the power law index of the correlation beta = 0.5, where F_{nu,OPT} propto F_X^beta. The discrete cross-correlation function reveals a peak at an X-ray lag of 2 - 14 days, which could be the viscous timescale. However, adopting the least squares method the strongest correlation is at a lag of 0 +/- 4 days, consistent with X-ray reprocessing on the surfac...

  17. Baryons in the relativistic jets of the stellar-mass black hole candidate 4U 1630-47

    CERN Document Server

    Trigo, María Díaz; Migliari, Simone; Broderick, Jess W; Tzioumis, Tasso

    2013-01-01

    Accreting black holes are known to power relativistic jets, both in stellar-mass binary systems and at the centres of galaxies. The power carried away by the jets, and hence the feedback they provide to their surroundings, depends strongly on their composition. Jets containing a baryonic component should carry significantly more energy than electron-positron jets. While energetic considerations and circular polarisation measurements have provided conflicting circumstantial evidence for the presence or absence of baryons, the only system in which baryons have been unequivocally detected in the jets is the X-ray binary SS 433. Here we report the detection of Doppler-shifted X-ray emission lines from a more typical black hole candidate X-ray binary, 4U1630-47, coincident with the reappearance of radio emission from the jets of the source. We argue that these lines arise in a jet with velocity 0.66c, thereby establishing the presence of baryons in the jet. Such baryonic jets are more likely to be powered by the a...

  18. Spectral state evolution of 4U~1820-30: the stability of the spectral index of Comptonization tail

    CERN Document Server

    Titarchuk, Lev; Frontera, Filippo

    2013-01-01

    We analyze the X-ray spectra and their timing properties of the compact X-ray binary 4U~1820-30. We establish a number of spectral transitions in this source seen with BeppoSAX and RXTE. During the RXTE observations (1996 -- 2009), the source were approximately 75% of its time in the soft state making the lower banana and upper banana transitions combined with long-term low-high state transitions. We reveal that all of the X-ray spectra of 4U~1820-30 are fit by a composition of a thermal (blackbody) component, a Comptonization component (COMPTB) and a Gaussian-line component. Thus using this spectral analysis we find that the photon power-law index Gamma of the Comptonization component is almost unchangeable (Gamma~2) while the electron temperature kT_e changes from 2.9 to 21 keV during these spectral events. We also establish that for these spectral events the normalization of COMPTB component (which is proportional to mass accretion rate, \\dot M increases by factor 8 when kT_e decreases from 21 keV to 2.9 k...

  19. The optical ephemeris and X-ray variability of 4U 1735-44 (V926 Sco)

    CERN Document Server

    Giles, A B

    2012-01-01

    Optical observations of the low mass X-ray binary 4U 1735-44 were obtained during 1997-2007 and combined with earlier published observations from 1984-1993 to refine the ephemeris for the system. The linear fit for the time of maximum optical light has the ephemeris HJD = 2445904.0494(90) + [ N x 0.19383222(29)] with a value of chi^2 = 253.5$ for 16 dof and a scatter about phase zero of sigma = 0.061. The new data reconciles the discrepancy between the previous ephemeris and the more recent spectral ephemeris based on emission from the companion star which defined the systems true dynamical phase zero. The optical maximum for 4U 1735-44 now occurs at spectral phase 0.47 \\pm 0.05 and thus supports the classic model for an LMXB system. Our data further supports the standard model in several ways. The mean optical flux shows a positive correlation with the RXTE ASM X-ray flux, the relative increases suggesting that the non-X-ray induced optical flux from the companion is < 14 percent of the total optical ligh...

  20. The high energy X-ray spectrum of 4U 1700-37 observed from OSO 8

    Science.gov (United States)

    Dolan, J. F.; Coe, M. J.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Orwig, L. E.; Maurer, G. S.

    1980-01-01

    The most intense hard X-ray source in the confused region in Scorpius has been identified as 4U 1700-37 (=HD 153919). Observations extending over three binary periods in 1978 September were carried out with the high-energy X-ray spectrometer on OSO 8. The 3.4 day modulation is seen above 20 keV with the intensity during eclipse being consistent with zero flux. The photonumber spectrum from 20 to 150 keV is well represented by a single power law with a photonumber spectral index of -2.77 + or - 0.35 or by a thermal bremsstrahlung spectrum with kT = 27 (+15, -7)keV. The counting rate above 20 keV outside of eclipse shows no evidence for the 96.8 minute X-ray modulation previously reported at lower energies. Despite the difficulties that exist in reconciling both the lack of periodic modulation in the emitted X-radiation and the orbital dynamics of the system with our currently accepted theories of the evolution and physical properties of neutron stars, the observed properties of 4U 1700-37 are all consistent with the source being a spherically accreting neutron star rather than a black hole.

  1. A white dwarf merger as progenitor of the anomalous X-ray pulsar 4U 0142+61?

    CERN Document Server

    Rueda, J A; Izzo, L; Ruffini, R; Aguilar, P Loren; Kulebi, B; Siguan, G Aznar; Berro, E Garcia

    2013-01-01

    It has been recently proposed that massive fast-rotating highly-magnetized white dwarfs could describe the observational properties of some of Soft Gamma-Ray Repeaters (SGRs) and Anomalous X-Ray Pulsars (AXPs). Moreover, it has also been shown that high-field magnetic (HFMWDs) can be the outcome of white dwarf binary mergers. The products of these mergers consist of a hot central white dwarf surrounded by a rapidly rotating disk. Here we show that the merger of a double degenerate system can explain the characteristics of the peculiar AXP 4U 0142+61. This scenario accounts for the observed infrared excess. We also show that the observed properties of 4U 0142+6 are consistent with an approximately $1.2 M_{\\sun}$ white dwarf, remnant of the coalescence of an original system made of two white dwarfs of masses $0.6\\, M_{\\sun}$ and $1.0\\, M_{\\sun}$. Finally, we infer a post-merging age $\\tau_{\\rm WD}\\approx 64$ kyr, and a magnetic field $B\\approx 2\\times 10^8$ G. Evidence for such a magnetic field may come from th...

  2. Kilohertz Quasi-Periodic Oscillation Peak Separation is not Constant in the Atoll Source 4U 1608-52

    CERN Document Server

    Méndez, M; Wijnands, R; Ford, E C; Van Paradijs, J; Vaughan, B A; Méndez, Mariano; Van der Klis, Michiel; Wijnands, Rudy; Ford, Eric C.; Van Paradijs, Jan; Vaughan, Brian A.

    1998-01-01

    We present new Rossi X-ray Timing Explorer observations of the low-mass X-ray binary 4U 1608-52 during the decay of its 1998 outburst. We detect by a direct FFT method the existence of a second kilohertz quasi-periodic oscillation (kHz QPO) in its power density spectrum, previously only seen by means of the sensitivity-enhancing `shift and add' technique. This result confirms that 4U 1608-52 is a twin kHz QPO source. The frequency separation between these two QPO decreased significantly, from 325.5 +/- 3.4 Hz to 225.3 +/- 12.0 Hz, as the frequency of the lower kHz QPO increased from 470 Hz to 865 Hz, in contradiction with a simple beat-frequency interpretation. This change in the peak separation of the kHz QPOs is closely similar to that previously seen in Sco X-1, but takes place at a ten times lower average luminosity. We discuss this result within the framework of models that have been proposed for kHz QPO. Beat frequency models where the peak separation is identified with the neutron star spin rate, as we...

  3. Interacting binaries

    CERN Document Server

    Shore, S N; van den Heuvel, EPJ

    1994-01-01

    This volume contains lecture notes presented at the 22nd Advanced Course of the Swiss Society for Astrophysics and Astronomy. The contributors deal with symbiotic stars, cataclysmic variables, massive binaries and X-ray binaries, in an attempt to provide a better understanding of stellar evolution.

  4. Relativistic model of neutron stars in X-ray binary

    Science.gov (United States)

    Kalam, Mehedi; Hossein, Sk Monowar; Islam, Rabiul; Molla, Sajahan

    2017-02-01

    In this paper, we study the inner structure of some neutron stars from theoretical as well as observational points of view. We calculate the probable radii, compactness (u) and surface redshift (Zs) of five neutron stars (X-ray binaries) namely 4U 1538-52, LMC X-4, 4U 1820-30, 4U 1608-52, EXO 1745-248. Here, we propose a stiff equation of state (EoS) of matter distribution which relates pressure with matter density. Finally, we check the stability of such kind of theoretical structure.

  5. XMM-Newton Survey of Globular Cluster Ultracompact Binaries

    Science.gov (United States)

    Chakrabarty, Deepto

    2005-01-01

    Our program consisted of an observation of a single source, 4U 0513-40, which we had previously identified as a candidate ultracompact binary (a system with an orbital period below 1 hour). Several other known or suspected ultracompact binaries have shown unusual elemental abundance ratios in their X-ray spectra. In this program, however, our observation found no unusual abundance ratios in the spectrum of 4U 0513-40. This result was included, along with results from a separate Chandra program, in a paper submitted for publication in the Astrophysical Journal.

  6. A comparison of the fast timing behaviour of 4U 1705-44 to that of 4U 1608-52 and Cyg X-1

    CERN Document Server

    Berger, M

    1998-01-01

    We studied the fast timing behaviour of the atoll source 4U 1705-44 using the entire EXOSAT dataset, four observations covering a total of 230,000 seconds of 1-20 keV spectral and timing data. In one of the observations, 4U 1705-44 was in a low intensity "island" state and had an unusually hard spectrum. The fast timing analysis of this hard island state shows a power spectrum very similar to that of black hole candidates in the "low state", with a flat-topped band-limited noise component that gradually steepens towards higher frequency. We perform for the first time a quantitative comparison of the timing behaviour of an atoll source in the hard island state (4U 1705-44) with that of a black hole candidate in the low state (Cygnus X-1). We also compare the power spectrum of 4U 1705-44 in the hard island state with those of the atoll source 4U 1608-52 in a similar state as reported by Yoshida et al. (1993). Our results confirm that there are similarities between the fast timing behaviour of the hard island st...

  7. The disk wind in the rapidly spinning stellar-mass black hole 4U 1630-472 observed with NuSTAR

    DEFF Research Database (Denmark)

    King, Ashley L.; Walton, Dominic J.; Miller, Jon M.

    2014-01-01

    We present an analysis of a short NuSTAR observation of the stellar-mass black hole and low-mass X-ray binary 4U 1630-472. Reflection from the inner accretion disk is clearly detected for the first time in this source, owing to the sensitivity of NuSTAR. With fits to the reflection spectrum, we...... find evidence for a rapidly spinning black hole, (1σ statistical errors). However, archival data show that the source has relatively low radio luminosity. Recently claimed relationships between jet power and black hole spin would predict either a lower spin or a higher peak radio luminosity. We also...

  8. Modeling of oxygen-neon dominated accretion disks in Ultracompact x-ray binaries: 4u 1626-67

    Directory of Open Access Journals (Sweden)

    K. Werner

    2004-01-01

    Full Text Available Presentamos los primeros resultados computacionales de espectros sint eticos de discos de acreci on pobres en H/He en ultracompactas LMXBs. Nuestro objetivo es la determinaci on de la composici on qu mica de la estrella donadora de muy baja masa que forma el n ucleo de lo que fue una enana blanca C/O. El an alisis de abundancias nos permite obtener conclusiones sobre el asentamiento gravitacional en WDs, un importante proceso que afecta a los tiempos de enfriamiento y a los per odos pulsantes de los modos g.

  9. A look with BeppoSAX at the low-luminosity Galactic X-ray source 4U 2206+54

    CERN Document Server

    Masetti, N; Amati, L; Del Sordo, S; Frontera, F; Orlandini, M; Palazzi, E

    2004-01-01

    A pointed observation on the low-luminosity galactic source 4U 2206+54 was carried out on November 1998 with BeppoSAX in order to try to solve the open problems for this source. The light curve of 4U 2206+54 shows erratic variability on a timescale of about 1 hour; neither hardness variations nor time periodicities are detected throughout this 67 ks long observation. Thanks to the wide spectral coverage capabilities of BeppoSAX we could observe the source X-ray continuum over three energy decades, from 0.6 to 60 keV. The spectrum could be equally well fitted either with a blackbody plus Comptonization or with a high energy cutoff power law. No iron emission around 6.5 keV was detected, while a tentative detection of a cyclotron resonant feature in absorption is presented. Comparison of the present BeppoSAX data with the information available in literature for this source suggests that 4U 2206+54 is a close binary system in which a (possibly magnetized) NS is accreting from the companion star wind.

  10. The Bursting Behavior of 4U 1728-34: Parameters of a Neutron Star and Geometry of a NS-disk system

    Science.gov (United States)

    Shaposhnikov, Nickolai; Titarchuk, Lev; Haber, Frank

    2003-01-01

    We analyze a set of Type I X-ray bursts from the low mass X-ray binary 4U 1728-34, observed with Rossi X-ray Timing Explorer (RXTE). We infer the dependence of the neutron star (NS) mass and radius with respect to the assumed distance to the system using an analytical model of X-ray burst spectral formation. The model behavior clearly indicates that the burster atmosphere is helium-dominated. Our results strongly favor the soft equation of state (EOS) of NS for 4U 1728-34. We find that distance to the source should be within 4.5-5.0 kpc range. We obtain rather narrow constrains for the NS radius in 8.7-9.7 km range and interval 1.2-1.6 Ma for NS mass for this particular distance range. We uncover a temporal behavior of red-shift corrected burst flux for the radial expansion episodes and we put forth a dynamical evolution scenario for the NS accretion disk geometry during which an expanded envelope affects the accretion disk and increases the area of the neutron star exposed to the Earth observer. In the framework of this scenario we provide a new method for the estimation of the inclination angle which leads to the value of approximately 50 degrees for 4U 1728-34.

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

    CERN Document Server

    Gong, Biping

    2014-01-01

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

  12. Orbital Evolution and orbital phase resolved spectroscopy of the HMXB pulsar 4U 1538-52 with RXTE-PCA and BeppoSAX

    CERN Document Server

    Mukherjee, U; Paul, B; Naik, S; Bhatt, N

    2007-01-01

    We report here results from detailed timing and spectral studies of the high mass X-ray binary pulsar 4U~1538--52 over several binary periods using observations made with the Rossi X-ray Timing Explorer (RXTE) and BeppoSAX satellites. Pulse timing analysis with the 2003 RXTE data over two binary orbits confirms an eccentric orbit of the system. Combining the orbitial parameters determined from this observation with the earlier measurements we did not find any evidence of orbital decay in this X-ray binary. We have carried out orbital phase resolved spectroscopy to measure changes in the spectral parameters with orbital phase, particularly the absorption column density and the iron line flux. The RXTE-PCA spectra in the 3--20 keV energy range were fitted with a power law and a high energy cut-off alongwith a Gaussian line at $\\sim$ 6.4 keV, whereas the BeppoSAX spectra needed only a power law and Gaussian emission line at $\\sim$ 6.4 keV in the restricted energy range of 0.3--10.0 keV. An absorption along the l...

  13. Investigating the Long-term Variability of 4U1705-44; Evidence for an Underlying Nonlinear Double-Welled Oscillator

    Science.gov (United States)

    Phillipson, Rebecca; Boyd, Patricia T.; Smale, Alan P.

    2016-04-01

    The bright low-mass X-ray binary 4U1705-44 exhibits long-term semi-periodic variability with a timescale of several hundred days. The All-Sky Monitor (ASM) aboard the Rossi X-ray Timing Explorer (RXTE) and the Japanese X-ray All-Sky Monitor (MAXI) aboard the International Space Station together have continuously observed the source from December 1995 through the present. The combined ASM-MAXI data provides a continuous time series over fifty times the length of the timescale of interest. The phase space embedding of the flux versus its first derivative shows a strong resemblance to a double-welled nonlinear oscillator. When comparing our time series against well-known nonlinear oscillators, we find that 4U1705-44 exhibits behavior akin to the Duffing oscillator. Topological analysis can help us identify ‘fingerprints’ in the phase space of a system unique to its equations of motion. If such ‘fingerprints’ are the same between two systems, then their equations of motion must be closely related. We therefore found a range of parameters for which the Duffing oscillator closely follows the time evolution of 4U1705-44 and from this range chose 6 different numerical Duffing time series. We can extract low-period, unstable periodic orbits from both the 4U1705-44 and numerical Duffing time series and compare their topological information in phase space, such as their relative rotation rates. We argue that the associated period-1 orbit in 4U1705-44 has a period between 130 and 170 days. The driving periods of our 6 numerical time series correspond to 140 to 175 days. Assigning a logical sequence name to each orbit, the relative rotation rates can be compiled into a unique ‘intertwining’ matrix. The numerical Duffing time series and the 4U1705-44 intertwining matrices are identical, which provides strong evidence that they share the same underlying template. The implications of this equivalence suggests that we can look to the Duffing equation to describe the X

  14. Ultracompact X-Ray Binaries with Neon-Rich Degenerate Donors

    CERN Document Server

    Juett, A M; Chakraborty, D; Juett, Adrienne M.; Psaltis, Dimitrios; Chakrabarty, Deepto

    2001-01-01

    There are three low-mass X-ray binaries (4U 0614+091, 2S 0918-549, and 4U 1543-624) for which broad line emission near 0.7 keV was previously reported. A recent high-resolution observation of 4U 0614+091 with the Chandra/LETGS found evidence for an unusually high Ne/O abundance ratio along the line of sight but failed to detect the previously reported 0.7 keV feature. We have made a search of archival ASCA spectra and identified a fourth source with the 0.7 keV feature, the 20-min ultracompact binary 4U 1850-087. In all four of these sources, the 0.7 keV residual is eliminated from the ASCA spectra by allowing excess photoelectric absorption due to a non-solar relative abundance of neon, just as in the LETGS spectrum of 4U 0614+091. The optical properties of these systems suggest that all four are ultracompact (P_orb<80 min) binaries. We propose that there is excess neon local to each of these sources, as also found in the ultracompact binary pulsar 4U 1626-67. We suggest that the mass donor in these syste...

  15. Millihertz Quasi-periodic Oscillations in 4U 1636–536: Putting Possible Constraints on the Neutron Star Size

    Science.gov (United States)

    Stiele, H.; Yu, W.; Kong, A. K. H.

    2016-11-01

    Based on previous studies of quasi-periodic oscillations (QPOs) in neutron star (NS) low-mass X-ray binaries, mHz QPOs are believed to be related to “marginally stable” burning on the NS surface. Our study of phase-resolved energy spectra of these oscillations in 4U 1636–53 shows that the oscillations are not caused by variations in the blackbody temperature of the NS, but reveals a correlation between the change of the count rate during the mHz QPO pulse and the spatial extent of a region emitting blackbody emission. The maximum size of the emission area, {R}{BB}2={216.7}-86.4+93.2 km2, provides direct evidence that the oscillations originate from a variable surface area constrained on the NS and are therefore not related to instabilities in the accretion disk. The obtained lower limit on the size of the NS (11.0 km) rules out equations of state that prefer small NS radii. Observations of mHz QPOs in NS LMXBs with NICER and eXTP will reduce the statistical uncertainty in the lower limit on the NS radius, which together with better estimates of the hardening factor and distance, will allow for improved discrimination between different equations of state and compact star models. Furthermore, future missions will allow us to measure the peak blackbody emission area for a single mHz QPO pulse, which will push the lower limit to larger radii.

  16. The cooling phase of Type-I X-ray bursts in 4U 1636-53

    CERN Document Server

    Zhang, Guobao; Altamirano, Diego

    2010-01-01

    Time-resolved spectra during the cooling phase of thermonuclear X-ray bursts in low-mass X-ray binaries (LMXBs) can be used to measure the radii and masses of neutron stars. We analyzed ~ 300 bursts of the LMXB 4U 1636-53 using data from the Rossi X-ray Timing Explorer. We divided the bursts in three groups, photospheric radius expansion (PRE), hard non-PRE and soft non-PRE bursts, based on the properties of the bursts and the state of the source at the time of the burst. For the three types of bursts, we found that the average relation between the bolometric flux and the temperature during the cooling phase of the bursts is significantly different from the canonical $F \\propto T^4$ relation that is expected if the apparent emitting area on the surface of the neutron star remains constant as the flux decreases during the decay of the bursts. We also found that a single power law cannot fit the average flux-temperature relation for any of the three types of bursts, and that the flux-temperature relation for th...

  17. Broad iron emission line and kilohertz quasi-periodic oscillations in the neutron star system 4U 1636-53

    CERN Document Server

    Sanna, Andrea; Altamirano, Diego; Belloni, Tomaso; Hiemstra, Beike; Linares, Manuel

    2014-01-01

    Both the broad iron (Fe) line and the frequency of the kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low-mass X-ray binaries (LMXBs) can potentially provide independent measures of the inner radius of the accretion disc. We use XMM-Newton and simultaneous Rossi X-ray Timing Explorer observations of the LMXB 4U 1636-53 to test this hypothesis. We study the properties of the Fe-K emission line as a function of the spectral state of the source and the frequency of the kHz QPOs. We find that the inner radius of the accretion disc deduced from the frequency of the upper kHz QPO varies as a function of the position of the source in the colour-colour diagram, in accordance with previous work and with the standard scenario of accretion disc geometry. On the contrary, the inner disc radius deduced from the profile of the Fe line is not correlated with the spectral state of the source. The values of the inner radius inferred from kHz QPOs and Fe lines, in four observations, do not lead to a consisten...

  18. Dependence of the orbital modulation of X-rays from 4U 1820-303 on the accretion rate

    CERN Document Server

    Zdziarski, A A; Wen, L

    2007-01-01

    We report the discovery, using XTE data, of a dependence of the X-ray orbital modulation depth on the X-ray spectral state in the ultracompact atoll binary 4U 1820-303. This state (measured by us by the position on the X-ray colour-colour diagram) is tightly coupled to the accretion rate, which, in turn, is coupled to the phase of the 170-d superorbital cycle of this source. The modulation depth is much stronger in the high-luminosity, so-called banana, state than in the low-luminosity, island, state. We find the X-ray modulation is independent of energy, which rules out bound-free X-ray absorption in an optically thin medium as the cause of the modulation. We also find a significant dependence of the offset phase of the orbital modulation on the spectral state, which favours the model in which the modulation is caused by scattering in hot gas around a bulge at the disc edge, which both size and the position vary with the accretion rate. Estimates of the source inclination appear to rule out a model in which ...

  19. INTEGRAL spectral variability study of the atoll 4U 1820-30: first detection of hard X-ray emission

    CERN Document Server

    Tarana, A; Ubertini, P; Zdziarski, A A; Tarana, Antonella; Bazzano, Angela; Ubertini, Pietro; Zdziarski, Andrzej A.

    2006-01-01

    We study the 4-200 keV spectral and temporal behaviour of the low mass X-ray binary 4U 1820-30 with INTEGRAL during 2003-2005. This source as been observed in both the soft (banana) and hard (island) spectral states. A high energy tail, above 50 keV, in the hard state has been observed for the first time. This places the source in the category of X-ray bursters showing high-energy emission. The tail can be modeled as a soft power law component, with the photon index of ~2.4, on top of thermal Comptonization emission from a plasma with the electron temperature of kT_e~6 keV and optical depth of \\tau~4. Alternatively, but at a lower goodness of the fit, the hard-state broad band spectrum can be accounted for by emission from a hybrid, thermal-nonthermal, plasma. During this monitoring the source spent most of the time in the soft state, usual for this source, and the >~4 keV spectra are represented by thermal Comptonization with kT_e~3 keV and \\tau~6-7.

  20. Long-term quasi-periodicity of 4U 1636-536 resulting from accretion disc instability

    CERN Document Server

    Wisniewicz, Mateusz; Gondek-Rosinska, Dorota; Zdziarski, Andrzej A; Janiuk, Agnieszka

    2015-01-01

    We present the results of a study of the low-mass X-ray binary 4U 1636-536. We have performed temporal analysis of all available RXTE/ASM, Swift/BAT and MAXI data. We have confirmed the previously discovered quasi-periodicity of ~45 d present during ~2004, however we found it continued to 2006. At other epochs, the quasi-periodicity is only transient, and the quasi-period, if present, drifts. We have then applied a time-dependent accretion disc model to the interval with the significant X-ray quasi-periodicity. For our best model, the period and the amplitude of the theoretical light curve agree well with that observed. The modelled quasi-periodicity is due to the hydrogen thermal-ionization instability occurring in outer regions of the accretion disc. The model parameters are the average mass accretion rate (estimated from the light curves), and the accretion disc viscosity parameters, for the hot and cold phases. Our best model gives relatively low values of viscosity parameter for cold phase 0.01 and for h...

  1. Long-term quasi-periodicity of 4U 1636-536 resulting from accretion disc instability

    Science.gov (United States)

    Wisniewicz, Mateusz; Zdziarski, Andrzej; Janiuk, Agnieszka; Rosinska, Dorota; Slowikowska, Agnieszka

    2016-07-01

    We present the results of a study of the low-mass X-ray binary 4U 1636-536. We have performed temporal analysis of all available RXTE/ASM, RXTE/PCA, Swift/BAT and MAXI data. We have confirmed the previously discovered quasi-periodicity of ˜45 d present during ˜2004, however we found it continued to 2006. At other epochs, the quasi-periodicity is only transient, and the quasi-period, if present, drifts. We have then applied a time-dependent accretion disc model to the interval with the significant X-ray quasi-periodicity. For our best model, the period and the amplitude of the theoretical light curve agree well with that observed. The modelled quasi-periodicity is due to the hydrogen thermal-ionization instability occurring in outer regions of the accretion disc. The model parameters are the average mass accretion rate (estimated from the light curves), and the accretion disc viscosity parameters, α_{cold} and α_{hot}, for the hot and cold phases, respectively. Our best model gives relatively low values of α_{cold} and α_{hot}.

  2. Swift observations of two outbursts from the magnetar 4U 0142+61

    CERN Document Server

    Archibald, R F; Scholz, P; Beardmore, A P; Gehrels, N; Kennea, J A

    2016-01-01

    4U 0142+61 is one of a small class of persistently bright magnetars. Here we report on a monitoring campaign of 4U 0142+61 from 2011 July 26 - 2016 June 12 using the Swift X-ray Telescope, continuing a 16 year timing campaign with the Rossi X-ray Timing Explorer. We show that 4U 0142+61 had two radiatively loud timing events, on 2011 July 29 and 2015 February 28, both with short soft gamma-ray bursts, and a long-lived flux decay associated with each case. We show that the 2015 timing event resulted in a net spin-down of the pulsar due to over-recovery of a glitch. We compare this timing event to previous such events in other high-magnetic-field pulsars, and discuss net spin-down glitches now seen in several young, high-B pulsars.

  3. Burst and Outburst Characteristics of Magnetar 4U 0142+61

    CERN Document Server

    Gogus, Ersin; Roberts, Oliver J; Chakraborty, Manoneeta; Kaneko, Yuki; Gill, Ramandeep; Granot, Jonathan; van der Horst, Alexander J; Watts, Anna L; Baring, Matthew; Kouveliotou, Chryssa; Huppenkothen, Daniela; Younes, George

    2016-01-01

    We have compiled the most comprehensive burst sample from magnetar 4U 0142+61, comprising 27 bursts from its three burst-active episodes in 2011, 2012 and the latest one in 2015 observed with Swift/BAT and Fermi/GBM. Bursts from 4U 0142+61 morphologically resemble typical short bursts from other magnetars. However, 4U 0142+61 bursts are less energetic compared to the bulk of magnetar bursts. We uncovered an extended tail emission following a burst on 2015 February 28, with a thermal nature, cooling over a time-scale of several minutes. During this tail emission, we also uncovered pulse peak phase aligned X-ray bursts , which could originate from the same underlying mechanism as that of the extended burst tail, or an associated and spatially coincident but different mechanism.

  4. Orbital Evolution and Orbital Phase Resolved Spectroscopy of the HMXB Pulsar 4U 1538–52 with RXTE-PCA and BeppoSAX

    Indian Academy of Sciences (India)

    U. Mukherjee; H. Raichur; B. Paul; S. Naik; N. Bhatt

    2006-12-01

    We report here results from detailed timing and spectral studies of the high mass X-ray binary pulsar 4U 1538–52 over several binary periods using observations made with the Rossi X-rayTiming Explorer (RXTE) and BeppoSAX satellites. Pulse timing analysis with the 2003 RXTE data over two binary orbits confirms an eccentric orbit of the system. Combining the orbitial parameters determined from this observation with the earlier measurements we did not find any evidence of orbital decay in this X-ray binary. We have carried out orbital phase resolved spectroscopy to measure changes in the spectral parameters with orbital phase, particularly the absorption column density and the iron line flux. The RXTE-PCA spectra in the 3–20 keV energy range were fitted with a power law and a high energy cut-off alongwith a Gaussian line at ∼ 6.4 keV, whereas the BeppoSAX spectra needed only a power law and Gaussian emission line at ∼ 6.4 keV in the restricted energy range of 0.3–10.0 keV. An absorption along the line of sight was included for both the RXTE and BeppoSAX data. The variation of the free spectral parameters over the binary orbit was investigated and we found that the variation of the column density of absorbing material in the line of sight with orbital phase is in reasonable agreement with a simple model of a spherically symmetric stellar wind from the companion star.

  5. The Unusual Long Term Variability of LMXB 4U 1705-440---Fingerprints of Chaotic Evolution?

    Science.gov (United States)

    Boyd, Patricia T.; Phillipson, Rebecca; Smale, Alan P.

    2016-04-01

    The bursting Atoll source 4U 1705-44, exhibits high amplitude, long-term aperiodic variability on characteristic timescales of several hundred days. The brightness of the system makes it continuously observable by a variety of all-sky monitors. We combine data from te All-Sky Monitor (ASM) aboard the Rossi X-ray Timing Explorer (RXTE) and MAXI, the Japanese X-ray All-Sky Monitor aboard the International Space Station, resulting in a continuous, uninterrupted, evenly spaced time series containing over fifty cycles at the timescale of interest. We construct a two-dimensional phase space from the flux versus its first derivative, and find a strong resemblence to the canonical double-welled nonlinear Duffing osciallator. We uncover several low-order unstable periodic orbits embedded in the light curve of 4U 1705-44, which imply that the "period-1" orbit lasts ~120 days. We find clear signatures of period-1, period-2 and period-3 orbits and extract these to calculate their topological behavior in phase space. The topoligical relations suggest that the equations describing the long term evolution of 4U 1705-44 are similar to those of the Duffing oscillator. This puts limits on the allowable models describing the longterm variability of 4U 1705-44 and, by extention, to the allowable models describing other systems which show non-periodic superorbital variability.

  6. 1 in 4 U.S. Adults, 1 in 10 Teens Use Tobacco

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_163240.html 1 in 4 U.S. Adults, 1 in 10 Teens Use Tobacco About 40 percent of ... 9 percent of teens said they used tobacco in the past month. Tobacco products included cigarettes, cigars, ...

  7. 9 CFR 102.4 - U.S. Veterinary Biologics Establishment License.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false U.S. Veterinary Biologics... LICENSES FOR BIOLOGICAL PRODUCTS § 102.4 U.S. Veterinary Biologics Establishment License. (a) Before a U.S. Veterinary Biologics Establishment License will be issued by the Administrator for any establishment,...

  8. The Bursting Behavior of 4U 1728-34: Parameters of a Neutron Star and Geometry of a NS-disk system

    CERN Document Server

    Shaposhnikov, N; Haberl, F; Shaposhnikov, Nickolai; Titarchuk, Lev; Haberl, Frank

    2003-01-01

    We analyze a set of Type I X-ray bursts from the low mass X-ray binary 4U 1728 -34, observed with Rossi X-ray Timing Explorer (RXTE). and we implement an analytical model of X-ray spectral formation in the neutron star (NS) atmosphere during a burst. We infer the dependence of the neutron star mass and radius with respect to the assumed distance to the system using an analytical model of X-ray burst spectral formation. The model behavior clearly indicates that the burster atmosphere is helium-dominated. Our results strongly favor the soft equation of state (EOS) of NS for 4U 1728-34. We find that distance to the source should be within 4.5-5.0 kpc range. We obtain rather narrow constrains for the NS radius in 8.7-9.7 km range and interval 1.2-1.6 solar masses for NS mass for this particular distance range. We uncover a temporal behavior of red-shift corrected burst flux for the radial expansion episodes and we put forth a dynamical evolution scenario for the NS--accretion disk geometry during which an expande...

  9. The cooling phase of Type I X-ray bursts observed with RXTE in 4U 1820-30 does not follow the canonical F - T^4 relation

    CERN Document Server

    García, Federico; Méndez, Mariano

    2013-01-01

    We analysed the complete set of bursts from the neutron-star low-mass X-ray binary 4U 1820-30 detected with the Rossi X-ray Timing Explorer (RXTE). We found that all are photospheric radius expansion bursts, and have similar duration, peak flux and fluence. From the analysis of time-resolved spectra during the cooling phase of the bursts, we found that the relation between the bolometric flux and the temperature is very different from the canonical F - T^4 relation that is expected if the apparent emitting area on the surface of the neutron star remains constant. The flux-temperature relation can be fitted using a broken power law, with indices 2.0$\\pm$0.3 and 5.72$\\pm$0.06. The departure from the F - T^4 relation during the cooling phase of the X-ray bursts in 4U 1820-30 could be due to changes in the emitting area of the neutron star while the atmosphere cools-down, variations in the colour-correction factor due to chemical evolution, or the presence of a source of heat, e.g. residual hydrogen nuclear burni...

  10. Determination of the turbulent parameter in the accretion disks: effects of self-irradiation in 4U 1543-47 during the 2002 outburst

    CERN Document Server

    Lipunova, G V

    2016-01-01

    The accretion disk around black hole in 4U 1543-47, a binary system with the orbital period of 1.116 day, can have the size of about $4 \\mathrm{R}_\\odot$. An outburst of 4U 1543-47 in 2002 has a characteristic exponential decay time of about 15 days. Such fast decay cannot be explained by the viscous evolution in the whole disk, and the evolution of the inner hot disk with changing size should be considered. Accretion rate evolution of this burst is obtained from spectral modelling of the archival RXTE/PCA data. Estimates on $\\alpha$ are derived by fitting observed $\\dot M(t)$ to the numerical results of the code Freddi for a range of black hole masses and Kerr parameters. If the self-irradiation of the disk by the emission from its center, which is parametrized by factor $C_\\mathrm{irr}$, was as high as suggested for other X-ray transients then the disk was completely ionized and the short time of the decay required huge $\\alpha$. Different scenarios are possible depending on the degree of irradiation. If ir...

  11. Finding a 60.9-day orbital period for the HMXB 4U 1036-56 with the Swift-BAT monitoring

    CERN Document Server

    Cusumano, G; La Parola, V; Masetti, N; D'Aì, A; Tagliaferri, G

    2013-01-01

    Since November 2004, the Burst Alert Telescope on board Swift is producing a monitoring of the entire sky in the 15-150 keV band, recording the timing and spectral behavior of the detected sources. In this letter we study the properties of the HMXB 4U 1036-56 using both the BAT survey data and those from a Swift-XRT pointed observation. The timing analysis of the BAT light curve unveils a periodic modulation with a period of ~60.9 days, that we explain as the orbital period of the binary system. The position of 4U 1036-56 on the Corbet diagram and the derived semi-major orbit axis (~180 R_dot) are consistent with the Be nature of its companion star. The intensity orbital profile averaged over 88 months of observations shows a large asymmetric shape with a minimum consistent with zero intensity, that could be related to the occultation of the neutron star by the supergiant companion. The source shows also a strong long term variability, going from high intensity states to quiescent states over a time scale of ...

  12. On the Constancy of the Photon Index of X-ray spectra of 4U~1728-34 through all spectral states

    CERN Document Server

    Seifina, Elena

    2011-01-01

    We present an analysis of the spectral properties observed in X-rays from Neutron Star X-ray binary 4U~1728-34 during transitions between the low and the high luminosity states when electron temperature kT_e of the Compton cloud monotonically decreases from 15 to 2.5 keV. We analyze the transition episodes from this source observed with BeppoSAX and RXTE. We find that the X-ray broad-band energy spectra of 4U~1728-34 during all spectral states can be modeled by a combination of a thermal (black body-like) component, a Comptonized component (which we herein denote COMPTB) and a Gaussian component. Spectral analysis using this model evidences that the photon power-law index Gamma is almost constant (Gamma=1.99+/-0.02) when kT_e changes from 15 to 2.5 keV during these spectral transitions. We explain this quasi-stability of the index by the model in which the spectrum is dominated by the strong thermal Comptonized component formed in the transition layer (TL) between the accretion disk and neutron star surface. ...

  13. Binary effectivity rules

    DEFF Research Database (Denmark)

    Keiding, Hans; Peleg, Bezalel

    2006-01-01

    is binary if it is rationalized by an acyclic binary relation. The foregoing result motivates our definition of a binary effectivity rule as the effectivity rule of some binary SCR. A binary SCR is regular if it satisfies unanimity, monotonicity, and independence of infeasible alternatives. A binary...... effectivity rule is regular if it is the effectivity rule of some regular binary SCR. We characterize completely the family of regular binary effectivity rules. Quite surprisingly, intrinsically defined von Neumann-Morgenstern solutions play an important role in this characterization...

  14. Possible detection of a cyclotron resonance scattering feature in the X-ray pulsar 4U 1909+07

    Energy Technology Data Exchange (ETDEWEB)

    Jaisawal, Gaurava K.; Naik, Sachindra [Astronomy and Astrophysics Division, Physical Research Laboratory, Ahmedabad 380009 (India); Paul, Biswajit, E-mail: gaurava@prl.res.in [Raman Research Institute, Sadashivnagar, C. V. Raman Avenue, Bangalore 560080 (India)

    2013-12-10

    We present timing and broad band spectral studies of the high-mass X-ray binary pulsar 4U 1909+07 using data from Suzaku observations during 2010 November 2-3. The pulse period of the pulsar is estimated to be 604.11 ± 0.14 s. Pulsations are seen in the X-ray light curve up to ∼70 keV. The pulse profile is found to be strongly energy-dependent: a complex, multi-peaked structure at low energy becomes a simple single peak at higher energy. We found that the 1-70 keV pulse-averaged continuum can be fit by the sum of a blackbody and a partial covering Negative and Positive power law with Exponential cutoff model. A weak iron fluorescence emission line at 6.4 keV was detected in the spectrum. An absorption-like feature at ∼44 keV was clearly seen in the residuals of the spectral fitting, independent of the continuum model adopted. To check the possible presence of a cyclotron resonance scattering feature (CRSF) in the spectrum, we normalized the pulsar spectrum with the spectrum of the Crab Nebula. The resulting Crab ratio also showed a clear dip centered at ∼44 keV. We performed statistical tests on the residuals of the spectral fitting and also on the Crab spectral ratio to determine the significance of the absorption-like feature and identified it as a CRSF of the pulsar. We estimated the corresponding surface magnetic field of the pulsar to be 3.8 × 10{sup 12} G.

  15. 超频很简单:映泰Tforce4 U SE主板

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    为了纪念成立20周年,映泰推出了纪念版TForce4 U SE主板。作为T系列主板,该主板更加注重超频性能,做工和用料得到了加强。在规格上,它与之前上市的DFI VENUS主板很相似。

  16. Optical pulsations from the anomalous X-ray pulsar 4U0142+61.

    Science.gov (United States)

    Kern, B; Martin, C

    2002-05-30

    Anomalous X-ray pulsars (AXPs) differ from ordinary radio pulsars in that their X-ray luminosity is orders of magnitude greater than their rate of rotational energy loss, and so they require an additional energy source. One possibility is that AXPs are highly magnetized neuron stars or 'magnetars' having surface magnetic fields greater than 10(14) G. This would make them similar to the soft gamma-ray repeaters (SGRs), but alternative models that do not require extreme magnetic fields also exist. An optical counterpart to the AXP 4U0142+61 was recently discovered, consistent with emission from a magnetar, but also from a magnetized hot white dwarf, or an accreting isolated neutron star. Here we report the detection of optical pulsations from 4U0142+61. The pulsed fraction of optical light (27 per cent) is five to ten times greater than that of soft X-rays, from which we conclude that 4U0142+61 is a magnetar. Although this establishes a direct relationship between AXPs and the soft gamma-ray repeaters, the evolutionary connection between AXPs, SGRs and radio pulsars remains controversial.

  17. INTEGRAL observation of renewed activity from 4U 1608-522

    DEFF Research Database (Denmark)

    Ishibashi, W.; Ferrigno, C.; Sánchez-Fernández, C.;

    2010-01-01

    for a total exposure time of 8.8 ks, can be fit by using an absorbed power-law model. We fixed the absorption column density at 1.2E22 cm² and obtained a power-law photon index of 2.8+/-0.4. The estimated source flux in the 3-10 keV energy band is 3.3E-10 ergs/cm²/s. During the whole observation time......, the source was not detected by IBIS/ISGRI. We derive an upper limit (5-sigma) on the X-ray flux of 5-10 mCrab in the 20-40 keV band. INTEGRAL is currently observing the field of GX 339-4 (March 4th-6th) and will continue monitoring of the inner Galactic Disk until the end of March. 4U 1608......On 3 March 2010 SuperAGILE detected an X-ray burst from the LMXB 4U 1608-522 (Atel #2461). Confirmation of the renewed activity of this transient source was reported by MAXI/GSC (Atel #2462). 4U1608-522 was in the IBIS/ISGRI and JEMX field of view during several observations between 2010-Feb-23 06...

  18. X-ray time variability across the atoll source states of 4U 1636--53

    CERN Document Server

    Altamirano, D; Méndez, M; Jonker, P G; Klein-Wolt, M; Lewin, W H G

    2008-01-01

    We have studied the rapid X-ray time variability in 149 pointed observations with the \\textit{Rossi X-ray Timing Explorer} (RXTE)'s Proportional Counter Array of the atoll source 4U~1636--53 in the banana state and, for the first time with RXTE, in the island state. We compare the frequencies of the variability components of 4U~1636--53 with those in other atoll and Z-sources and find that 4U~1636--53 follows the universal scheme of correlations previously found for other atoll sources at (sometimes much) lower luminosities. Our results on the hectohertz QPO suggest that the mechanism that sets its frequency differs from that for the other components, while the amplitude setting mechanism is common. A previously proposed interpretation of the narrow low-frequency QPO frequencies in different sources in terms of harmonic mode switching is not supported by our data, nor by some previous data on other sources and the frequency range that this QPO covers is found not to be related to spin, angular momentum or lum...

  19. Quit4U: The Effectiveness of Combining Behavioural Support, Pharmacotherapy and Financial Incentives to Support Smoking Cessation

    Science.gov (United States)

    Ormston, R.; van der Pol, M.; Ludbrook, A.; McConville, S.; Amos, A.

    2015-01-01

    The "quit4u" stop smoking service (SSS) was developed by National Health Service (NHS) Tayside for smokers in deprived areas of Dundee (UK). quit4u combined behavioural support and pharmacotherapy with financial incentives for each week that participants remained quit. A quasi-experimental study was undertaken with smokers using quit4u…

  20. Plataforma Tecnológica de Datos Abiertos Universitarios (OpenData4U)

    OpenAIRE

    2016-01-01

    La plataforma tecnológica de datos abiertos universitarios (OpenData4U) permite la publicación de datos abiertos de una universidad, así como su acceso de manera que se potencie su reutilización (a través de un portal de datos abiertos y de un API para desarrolladores), a la vez que se permite disponer de un portal de transparencia para una acceso fácil a los datos de manera comprensible por cualquier persona. Esta es la plataforma que usa la Universidad de Alicante en su proyecto de datos ab...

  1. Accretion regimes in the X-ray pulsar 4U 1901+03

    CERN Document Server

    Reig, P

    2016-01-01

    The source 4U 1901+03 is a high-mass X-ray pulsar than went into outburst in 2003. Observation performed with the Rossi X-ray Timing Explorer showed spectral and timing variability, including the detection of flares, quasi-periodic oscillations, complex changes in the pulse profiles, and pulse phase dependent spectral variability. We re-analysed the data covering the 2003 X-ray outburst and focused on several aspects of the variability that have not been discussed so far. These are the 10 keV feature and the X-ray spectral states and their association with accretion regimes, including the transit to the propeller state at the end of the outburst. We find that 4U 1901+03 went through three accretion regimes over the course of the X-ray outburst. At the peak of the outburst and for a very short time, the X-ray flux may have overcome the critical limit that marks the formation of a radiative shock at a certain distance above the neutron star surface. Most of the time, however, the source is in the subcritical re...

  2. Einstein SSS and MPC observations of Aql X-1 and 4U1820-30

    Science.gov (United States)

    Kelley, R. L.; Christian, D. J.; Schoelkopf, R. J.; Swank, J. H.

    1989-01-01

    The results of timing and spectral analyses of the X-ray sources Aql X-1 (X1908+005) and 4U1820-30 (NGC6624) are reported using data obtained with the Einstein SSS (Solid State Spectrometer) and MPC (Monitor Proportional Counter) instruments. A classic type I burst was observed from Aql X-1 in both detectors and a coherent modulation with a period of 131.66 + or - 0.02 ms and a pulsed fraction of 10 percent was detected in the SSS data. There is no evidence for a loss of coherance during the approximately 80 sec when the burst is observable. The 2 sigma upper limit on the rate of change of the pulse period is 0.00005s/s. It is argued that an asymmetrical burst occurring on a neutron star rotating at 7.6 Hz offers a plausible explanation for the oscillation. The data from 4U1820-30 show that the amplitude of the 685 sec modulation, identified as the orbital period, is independent of energy down to 0.6 keV. The SSS data show that the light curve in the 0.6 to 4.5 keV band is smoother than at higher energies.

  3. Eclipsing binaries in open clusters

    DEFF Research Database (Denmark)

    Southworth, John; Clausen, J.V.

    2006-01-01

    Stars: fundamental parameters - Stars : binaries : eclipsing - Stars: Binaries: spectroscopic - Open clusters and ass. : general Udgivelsesdato: 5 August......Stars: fundamental parameters - Stars : binaries : eclipsing - Stars: Binaries: spectroscopic - Open clusters and ass. : general Udgivelsesdato: 5 August...

  4. Optical I-band Linear Polarimetry of the Magnetar 4U 0142+61 with Subaru

    Science.gov (United States)

    Wang, Zhongxiang; Tanaka, Yasuyuki T.; Wang, Chen; Kawabata, Koji S.; Fukazawa, Yasushi; Itoh, Ryosuke; Tziamtzis, Anestis

    2015-12-01

    Magnetars are known to have optical and/or infrared (IR) emission, but the origin of the emission is not well understood. In order to fully study their emission properties, we have carried out for the first time optical linear polarimetry of the magnetar 4U 0142+61, which has been determined from different observations to have a complicated broadband spectrum over optical and IR wavelengths. From our I-band imaging polarimetric observation, conducted with the 8.2-m Subaru telescope, we determine the degree of linear polarization to be P = 1.0 ± 3.4%, or P ≤ 5.6% (90% confidence level). Considering models that were suggested for optical emission from magnetars, we discuss the implications of our result. The upper limit measurement indicates that, differing from radio pulsars, magnetars probably would not have strongly polarized optical emission if the emission arises from their magnetosphere as suggested.

  5. Chandra Takes on Heavy Jets and Massive Winds in 4U 1630-47

    Science.gov (United States)

    Neilsen, Joey

    2014-11-01

    Recently, Díaz Trigo et al. reported the discovery of relativistic baryons in a jet in XMM/ATCA observations of the 2012 outburst of the black hole 4U 1630-47. We present a search for a similarly massive jet earlier in the same outburst using high-resolution X-ray spectra from the Chandra HETGS. Despite a detection of radio emission with ATCA, we find no evidence of a heavy jet in the X-ray spectrum, with tight upper limits on the relativistic emission lines seen by Díaz Trigo eight months later. Instead, we find deep absorption lines from a massive, highly ionized disk wind, whose properties can be probed with detailed photoionization models. We explore several scenarios to explain the two modes of massive outflow in this remarkable black hole system.

  6. Optical I-band Linear Polarimetry of the Magnetar 4U 0142+61 with Subaru

    CERN Document Server

    Wang, Z; Wang, C; Kawabata, K S; Fukazawa, Y; Itoh, R; Tziamtzis, A

    2015-01-01

    The magnetar 4U~0142+61 has been well studied at optical and infrared wavelengths and is known to have a complicated broad-band spectrum over the wavelength range. Here we report the result from our linear imaging polarimetry of the magnetar at optical $I$-band. From the polarimetric observation carried out with the 8.2-m Subaru telescope, we determine the degree of linear polarization $P=1.0\\pm$3.4\\%, or $P\\leq$5.4\\% (90\\% confidence level). Considering models suggested for optical emission from magnetars, we discuss the implications of our result. The upper limit measurement indicates that different from radio pulsars, magnetars probably would not have strongly polarized optical emission if the emission arises from their magnetosphere as suggested.

  7. Binary mask programmable hologram.

    Science.gov (United States)

    Tsang, P W M; Poon, T-C; Zhou, Changhe; Cheung, K W K

    2012-11-19

    We report, for the first time, the concept and generation of a novel Fresnel hologram called the digital binary mask programmable hologram (BMPH). A BMPH is comprised of a static, high resolution binary grating that is overlaid with a lower resolution binary mask. The reconstructed image of the BMPH can be programmed to approximate a target image (including both intensity and depth information) by configuring the pattern of the binary mask with a simple genetic algorithm (SGA). As the low resolution binary mask can be realized with less stringent display technology, our method enables the development of simple and economical holographic video display.

  8. RXTE Observation of 4U 1630-47 During its 1998 Outburst

    Science.gov (United States)

    Dieters, Stefan W.

    1999-01-01

    During the 1998 outburst of 4U 1630-47 it was extensively observed with the Rossi X-ray Timing Explorer (RXTE). In order to cover the outburst more thoroughly our data (Obs. ID: 30178-0[1-2]- ) were combined with those of Cui et al. (Obs. ID: 30188-02-). These observations were later compared with the complementary observations. Power density and energy spectra have been made for each observation. The data was used to place radio and hard X-ray observations within context. Analysis of SAX (Satellite per Astronomia a raggi X) and BATSE (Burst and Transient Source Experiment) data was also included within the study. The count rate and position in hardness-intensity, color-color diagrams and simple spectral fits are used to track the concurrent spectral changes. The source showed seven distinct types of timing behavior, most of which show differences with the canonical black hole spectral/timing states. In marked contrast to previous outbursts, we find quasi-periodic oscillation (QPO) signals during nearly all stages of the outburst with frequencies between 0.06 Hz and 14 Hz and a remarkable variety of other characteristics. In particular we find large (up to 23% rms) amplitude QPO on the early rise. Later, slow 0.1 Hz semi- regular short (- 5 sec), 9 to 16% deep dips dominate the light curve. At this time there are two QPOS, one stable near 13.5 Hz and the other whose frequency drops from 6-8 Hz to - 4.5 Hz during the dips. BeppoSAX observations during the very late declining phase show 4U 1630-47 in a low state. These results will shortly be published. We are completing a detailed analysis of the energy spectra (in preparation). The QPO/noise properties are being correlated with the concurrent spectral changes. Detailed studies of the QPO are being undertaken using sophisticated timing analysis methods. Finally a comparison with the other outbursts of 1630-47 is being made.

  9. Π4U: A high performance computing framework for Bayesian uncertainty quantification of complex models

    Energy Technology Data Exchange (ETDEWEB)

    Hadjidoukas, P.E.; Angelikopoulos, P. [Computational Science and Engineering Laboratory, ETH Zürich, CH-8092 (Switzerland); Papadimitriou, C. [Department of Mechanical Engineering, University of Thessaly, GR-38334 Volos (Greece); Koumoutsakos, P., E-mail: petros@ethz.ch [Computational Science and Engineering Laboratory, ETH Zürich, CH-8092 (Switzerland)

    2015-03-01

    We present Π4U,{sup 1} an extensible framework, for non-intrusive Bayesian Uncertainty Quantification and Propagation (UQ+P) of complex and computationally demanding physical models, that can exploit massively parallel computer architectures. The framework incorporates Laplace asymptotic approximations as well as stochastic algorithms, along with distributed numerical differentiation and task-based parallelism for heterogeneous clusters. Sampling is based on the Transitional Markov Chain Monte Carlo (TMCMC) algorithm and its variants. The optimization tasks associated with the asymptotic approximations are treated via the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). A modified subset simulation method is used for posterior reliability measurements of rare events. The framework accommodates scheduling of multiple physical model evaluations based on an adaptive load balancing library and shows excellent scalability. In addition to the software framework, we also provide guidelines as to the applicability and efficiency of Bayesian tools when applied to computationally demanding physical models. Theoretical and computational developments are demonstrated with applications drawn from molecular dynamics, structural dynamics and granular flow.

  10. Observation of the Anomalous X-Ray Pulsar 4U 0142+61

    CERN Document Server

    Goehler, E; Staubert, R

    2004-01-01

    We present results of an observation of the anomalous X-ray pulsar 4U 0142+61 with the EPIC cameras on XMM-Newton performed on 2003 January 24. The pulse phase averaged spectrum can be best described by the sum of a black body with a temperature of kT_BB = 0.395(5) keV and a power law with photon index Gamma = 3.62(5). The unabsorbed 2-10 keV flux is ~7.2x10^-11 erg s^-1 cm^-2. No evidence for additional spectral features such as cyclotron lines is present. These results are consistent with those from an earlier Chandra observation in 2001 May. Phase resolved spectroscopy over the 8.6882(2) s period (MJD 52663.93) shows clear variations with pulse phase of Gamma, while kT_BB shows a small variation of ~12%. We confirm earlier conclusions by Oezel (2001) that the emission from AXPs is more likely to originate from neutron stars with one single and magnetically active region on the neutron star. The significantly different behavior of the soft and hard spectral components with pulse phase, however, cannot be fu...

  11. Π4U: A high performance computing framework for Bayesian uncertainty quantification of complex models

    Science.gov (United States)

    Hadjidoukas, P. E.; Angelikopoulos, P.; Papadimitriou, C.; Koumoutsakos, P.

    2015-03-01

    We present Π4U, an extensible framework, for non-intrusive Bayesian Uncertainty Quantification and Propagation (UQ+P) of complex and computationally demanding physical models, that can exploit massively parallel computer architectures. The framework incorporates Laplace asymptotic approximations as well as stochastic algorithms, along with distributed numerical differentiation and task-based parallelism for heterogeneous clusters. Sampling is based on the Transitional Markov Chain Monte Carlo (TMCMC) algorithm and its variants. The optimization tasks associated with the asymptotic approximations are treated via the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). A modified subset simulation method is used for posterior reliability measurements of rare events. The framework accommodates scheduling of multiple physical model evaluations based on an adaptive load balancing library and shows excellent scalability. In addition to the software framework, we also provide guidelines as to the applicability and efficiency of Bayesian tools when applied to computationally demanding physical models. Theoretical and computational developments are demonstrated with applications drawn from molecular dynamics, structural dynamics and granular flow.

  12. e-Support4U: An evaluation of academic writing skills support in practice.

    Science.gov (United States)

    Griffiths, Lauren; Nicolls, Barbara

    2010-11-01

    The Faculty of Society and Health at Buckinghamshire New University is committed to the widening participation agenda and to providing support that enables our students to achieve the requirements of the programme and registration. Literacy and numeracy skill development is an integral part of the academic modules of our current pre-registration curriculum. E-Support4U was launched in semester two of 2008 with the aim of extending academic writing support beyond the confines of the University and into the practice arena. Evaluation of the project tentatively suggests that the scaffold approach to academic writing, based on Salmon's 5-stage framework, may have contributed to a 100% pass rate for the reflective practice-based assignment for this cohort of students. However, participants experienced issues around access; differing levels of IT skills, dispersed placements that contributed to a lack of active collaboration within the group. Recommendations include early introduction of blended learning and incorporation of web 2.0 technology into the curriculum.

  13. Discovery of pulsations in the X-ray transient 4U 1901+03

    CERN Document Server

    Galloway, D K; Morgan, E H; Galloway, Duncan K.; Wang, Zhongxiang; Morgan, Edward H.

    2005-01-01

    We describe observations of the 2003 outburst of the hard-spectrum X-ray transient 4U 1901+03 with the Rossi X-ray Timing Explorer. The outburst was first detected in 2003 February by the All-Sky Monitor, and reached a peak 2.5-25 keV flux of 8x10^-9 ergs/cm^2/s (around 240 mCrab). The only other known outburst occurred 32.2 yr earlier, likely the longest presently known recurrence time for any X-ray transient. Proportional Counter Array (PCA) observations over the 5-month duration of the 2003 outburst revealed a 2.763 s pulsar in a 22.58 d orbit. The detection of pulsations down to a flux of 3x10^-11 ergs/cm^2/s (2.5-25 keV), along with the inferred long-term accretion rate of 8.1x10^-11 M_sun/yr (assuming a distance of 10 kpc) suggests that the surface magnetic field strength is below ~5x10^11 G. The corresponding cyclotron energy is thus below 4 keV, consistent with the non-detection of resonance features at high energies. Although we could not unambiguously identify the optical counterpart, the lack of a ...

  14. Torque reversals and pulse profile of the pulsar 4U 1626-67

    CERN Document Server

    Beri, Aru; Paul, Biswajit; Raichur, Harsha

    2014-01-01

    We review the pulse profile evolution of the unique accretion powered X-ray pulsar 4U 1626-67 over the last 40 years since its discovery. This pulsar showed two distinct eras of steady spin-up separated by a steady spin-down episode for about 18 years. In the present work, using data from different observatories active during each phase of spin-up and spin-down we establish a clear correlation between the accretion torque acting on this pulsar and its pulse profile. The energy resolved pulse profiles are identical in both the spin-up eras and quite different in the spin-down era, especially in the low energy band. This correlation, along with the already known feature of strong Quasi Periodic Oscillations (QPO) that was present only in the spin-down era, clearly establish two different accretion modes onto the neutron star which produce different pulse profiles and only one of which produces the QPOs.

  15. Disc-jet coupling in atoll-type neutron star X-ray binaries

    Energy Technology Data Exchange (ETDEWEB)

    Migliari, S.; Fender, R.P.; Rupen, M.; Jonker, P.G.; Klein-Wolt, M.; Hjellming, R.M.; Wachter, S.; Homan, J.; Klis, M. van der

    2004-06-01

    Atoll-type neutron star (NS) X-ray binaries share lots of properties with low/hard state black hole candidates (BHC) and are therefore the key sources for our understanding of the differences and similarities in the disc-jet connection of BHC and NS systems and the physical processes involved. We present the analysis of simultaneous radio (VLA) and X-ray (RXTE) observations of three atoll sources: 4U 1728-34, 4U 1820-30 and Ser X-1 (first radio detection). In 4U 1728-34 we find a significant correlation between radio and X-ray flux and, for the first time in an X-ray binary, a significant quantitative correlation between radio flux and X-ray timing features. As in BHCs it seems that also in atolls (i.e. in 4U 1820-30, Ser X-1 and in one observation of 4U 1728-34) the radio emission is 'quenched' above a certain luminosity, when the sources are in a softer state.

  16. RossiXTE monitoring of 4U 1636-53: I. Long-term evolution and kHz Quasi-Periodic Oscillations

    CERN Document Server

    Belloni, Tomaso; Mendez, Mariano; Motta, Sara; Ratti, Eva

    2007-01-01

    We have monitored the atoll-type neutron star low-mass X-ray binary 4U 1636-53 with the Rossi X-Ray Timing Explorer (RXTE) for more than 1.5 years. Our campaign consisted of short (~2 ks) pointings separated by two days, regularly monitoring the spectral and timing properties of the source. During the campaign we observed a clear long-term oscillation with a period of ~30-40 days, already seen in the light curves from the RXTE All-Sky Monitor, which corresponded to regular transitions between the hard (island) and soft (banana) states. We detected kHz QPOs in about a third of the observations, most of which were in the soft (banana) state. The distribution of the frequencies of the peak identified as the lower kHz QPO is found to be different from that previously observed in an independent data set. This suggests that the kHz QPOs in the system shows no intrinsically preferred frequency.

  17. Energy dependence of r.m.s amplitude of low frequency broadband noise and kHz quasi periodic oscillations in 4U 1608-52

    Science.gov (United States)

    Mandal, Soma

    2016-07-01

    The neutron star low mass X-ray binary 4U 1608-52 is known to show kHz QPOs as well as low frequency broad band noise. The energy dependence of the fractional r.m.s of these variations reflect the underlying radiative mechanism responsible for the phenomena. In this work we compute the energy depedence for 26 instances of kHz QPO observed by RXTE. We typically find as reported before, that the r.m.s increases with energy with slope of ˜0.5. This indicates that the variation is in the hot thermal compotonization component and in particular the QPO is likely to be driven by variation in the thermal heating rate of the hot plasma. For the same data, we compute the energy dependent r.m.s variability of the low frequency broad band noise component by considering the light curves. In contrast to the behaviour seen for the kHz QPO, the energy dependence is nearly flat i.e. the r.m.s. is energy independent. This indicates that the driver here may be the soft photon source. Thus the radiative mechanism driving the low frequency broad band noise and the high frequency QPO are different in nature.

  18. The Disk Wind in the Rapidly Spinning Stellar-mass Black Hole 4U 1630-472 Observed with NuSTAR

    Science.gov (United States)

    King, Ashley L.; Walton, Dominic J.; Miller, Jon M.; Barret, Didier; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Fabian, Andy C.; Furst, Felix; Hailey, Charles J.; Harrison, Fiona A.; Krivonos, Roman; Mori, Kaya; Natalucci, Lorenzo; Stern, Daniel; Tomsick, John A.; Zhang, William W.

    2014-01-01

    We present an analysis of a short NuSTAR observation of the stellar-mass black hole and low-mass X-ray binary 4U 1630-472. Reflection from the inner accretion disk is clearly detected for the first time in this source, owing to the sensitivity of NuSTAR. With fits to the reflection spectrum, we find evidence for a rapidly spinning black hole, a* = 0.985(+0.005/-0.014) (1 sigma statistical errors). However, archival data show that the source has relatively low radio luminosity. Recently claimed relationships between jet power and black hole spin would predict either a lower spin or a higher peak radio luminosity. We also report the clear detection of an absorption feature at 7.03 +/- 0.03 keV, likely signaling a disk wind. If this line arises in dense, moderately ionized gas (log xi = 3.6(+0.2/-0.3) and is dominated by He-like Fe xxv, the wind has a velocity of v/c = 0.043(+0.002/-0.007) (12900(+600/-2100) km s(exp -1)). If the line is instead associated with a more highly ionized gas (log xi = 6.1(+0.7/-0.6)), and is dominated by Fe xxvi, evidence of a blueshift is only marginal, after taking systematic errors into account. Our analysis suggests the ionized wind may be launched within 200-1100 Rg, and may be magnetically driven.

  19. Interacting binary stars

    CERN Document Server

    Sahade, Jorge; Ter Haar, D

    1978-01-01

    Interacting Binary Stars deals with the development, ideas, and problems in the study of interacting binary stars. The book consolidates the information that is scattered over many publications and papers and gives an account of important discoveries with relevant historical background. Chapters are devoted to the presentation and discussion of the different facets of the field, such as historical account of the development in the field of study of binary stars; the Roche equipotential surfaces; methods and techniques in space astronomy; and enumeration of binary star systems that are studied

  20. Organization of core spliceosomal components U5 snRNA loop I and U4/U6 Di-snRNP within U4/U6.U5 Tri-snRNP as revealed by electron cryomicroscopy.

    Science.gov (United States)

    Sander, Bjoern; Golas, Monika M; Makarov, Evgeny M; Brahms, Hero; Kastner, Berthold; Lührmann, Reinhard; Stark, Holger

    2006-10-20

    In eukaryotes, pre-mRNA exons are interrupted by large noncoding introns. Alternative selection of exons and nucleotide-exact removal of introns are performed by the spliceosome, a highly dynamic macromolecular machine. U4/U6.U5 tri-snRNP is the largest and most conserved building block of the spliceosome. By 3D electron cryomicroscopy and labeling, the exon-aligning U5 snRNA loop I is localized at the center of the tetrahedrally shaped tri-snRNP reconstructed to approximately 2.1 nm resolution in vitrified ice. Independent 3D reconstructions of its subunits, U4/U6 and U5 snRNPs, show how U4/U6 and U5 combine to form tri-snRNP and, together with labeling experiments, indicate a close proximity of the spliceosomal core components U5 snRNA loop I and U4/U6 at the center of tri-snRNP. We suggest that this central tri-snRNP region may be the site to which the prespliceosomal U2 snRNA has to approach closely during formation of the catalytic core of the spliceosome.

  1. The Be/X-ray transient 4U 0115+63/V635 Cassiopeiae. III. Quasi-cyclic variability

    CERN Document Server

    Reig, P; Negueruela, I; Arkharov, A A; Kudryavtseva, N A

    2006-01-01

    4u 0115+63 is one of the most active and best studied Be/X-ray transients. Previous studies of 4u0115+63 have led to the suggestion that it undergoes relatively fast quasi-cyclic activity. However, due to the lack of good coverage of the observations, the variability time scales are uncertain. Our objective is to investigate the long-term behaviour of 4u 0115+63 to confirm its quasi-cyclic nature and to explain its correlated optical/IR and X-ray variability. We have performed optical/IR photometric observations and optical spectroscopic observations of 4u 0115+63 over the last decade with unprecedented coverage. We have focused on the Halpha line variability and the long-term changes of the photometric magnitudes and colours and investigated these changes in correlation with the X-ray activity of the source. results The optical and infrared emission is characterised by cyclic changes with a period of ~ 5 years. This long-term variability is attributed to the state of the circumstellar disc around the Be star...

  2. The X-ray spectra of the black hole candidate 4U 1630-47 during its 2012 outburst

    NARCIS (Netherlands)

    Wang, Y.; Mendez, M.

    2015-01-01

    Diaz Trigo et al. (2013) reported the detection of three Doppler-shifted emission lines arising from baryonic matter in the jet of 4U 1630-47 during its 2012 outburst. Here we propose an alternative model that, without the need of the lines from the jet, and with less free parameters, fits the same

  3. 26 CFR 1.864-4 - U.S. source income effectively connected with U.S. business.

    Science.gov (United States)

    2010-04-01

    ... this subparagraph is not effectively connected with the active conduct by a nonresident alien... 26 Internal Revenue 9 2010-04-01 2010-04-01 false U.S. source income effectively connected with U... December 30, 1996 § 1.864-4 U.S. source income effectively connected with U.S. business. (a) In...

  4. Phase-resolved NuSTAR and SWIFT-XRT observations of magnetar 4U 0142+61

    DEFF Research Database (Denmark)

    Tendulkar, Shriharsh P.; Hascöet, Romain; Yang, Chengwei;

    2015-01-01

    We present temporal and spectral analysis of simultaneous 0.5-79 keV Swift-XRT and Nuclear Spectroscopic Telescope Array observations of the magnetar 4U 0142+61. The pulse profile changes significantly with photon energy between 3 and 35 keV. The pulse fraction increases with energy, reaching a v...

  5. Simultaneous X-ray/optical observations of GX 9+9 (4U 1728-16)

    CERN Document Server

    Kong, A K H; Homer, L; Kuulkers, E; O'Donoghue, D

    2006-01-01

    We report on the results of the first simultaneous X-ray (RXTE) and optical (SAAO) observations of the luminous low mass X-ray binary (LMXB) GX 9+9 in 1999 August. The high-speed optical photometry revealed an orbital period of 4.1958 hr and confirmed previous observations, but with greater precision. No X-ray modulation was found at the orbital period. On shorter timescales, a possible 1.4-hr variability was found in the optical light curves which might be related to the mHz quasi-periodic oscillations seen in other LMXBs. We do not find any significant X-ray/optical correlation in the light curves. In X-rays, the colour-colour diagram and hardness-intensity diagram indicate that the source shows characteristics of an atoll source in the upper banana state, with a correlation between intensity and spectral hardness. Time-resolved X-ray spectroscopy suggests that two-component spectral models give a reasonable fit to the X-ray emission. Such models consist of a blackbody component which can be interpreted as ...

  6. Compact Stars in low-mass X-ray binaries

    OpenAIRE

    Hossein, Sk. Monowar; Molla, Sajahan; Jafry, Md. Abdul Kayum; Kalam, Mehedi

    2014-01-01

    We propose a model for compact stars in low-mass X-ray binaries(LMXBs) namely KS 1731-260, EXO 1745-248 and 4U 1608-52. Here we investigate the physical phenomena of a compact star in the LMXBs. Using our model, we have calculated central density, surface density, mass(M) and red-shift for the above mentioned compact stars, which is very much consistent with the reported data. We also obtain the possible equation of state(EOS) of the stars which is physically acceptable.

  7. Propeller-Effect Interpretation of MAXI/GSC Light Curves of 4U 1608-52 and AqlX-1 and application to XTE J1701-462

    CERN Document Server

    Asai, K; Mihara, T; Sugizaki, M; Serino, M; Nakahira, S; Negoro, H; Ueda, Y; Yamaoka, K

    2013-01-01

    We present the luminosity dwell-time distributions during the hard states of low-mass X-ray binaries containing a neutron star, 4U 1608-52 and AqlX-1, observed with MAXI/GSC. The luminosity distributions show a steep cut-off in the low-luminosity side at $\\sim1.0 \\times 10^{36}$ erg s$^{-1}$ in both the two sources. The cut-off implies a rapid luminosity decrease in their outburst decay phases, and the feature can be interpreted as due the propeller effect. We estimated the surface magnetic field of the neutron star to be (0.5--1.6) $\\times 10^8$ G in 4U 1608-52 and (0.6--1.9) $\\times 10^8$ G in AqlX-1 from the cut-off luminosity. We applied the same propeller mechanism to the similar rapid luminosity decrease observed in the transient Z-source, XTE J1701-462, with RXTE/ASM. Assuming that spin period of the neutron star is in the order of milliseconds, the observed cut-off luminosity deduces surface magnetic field in the order of $10^9$ G.

  8. Search for Orbital Motion of the Pulsar 4U 1626-67: Candidate for a Neutron Star with a Supernova Fall-back Accretion Disk

    Indian Academy of Sciences (India)

    Chetana Jain; Biswajit Paul; Kaustubh Joshi; Anjan Dutta; Harsha Raichur

    2007-12-01

    We report here results from a new search for orbital motion of the accretion powered X-ray pulsar 4U 1626-67 using two different analysis techniques. X-ray light curve obtained with the Proportional Counter Array of the Rossi X-ray Timing Explorer during a long observation carried out in February 1996, was used in this work. The spin period and the local period derivative were first determined from the broad 2–60 keV energy band light curve and these were used for all subsequent timing analysis. In the first technique, the orbital phase dependent pulse arrival times were determined for different trial orbital periods in the range of 500 to 10,000 s. We have determined a 3 upper limit of 13 lt-ms on the projected semimajor axis of the orbit of the neutron star for most of the orbital period range, while in some narrow orbital period ranges, covering about 10% of the total orbital period range, it is 20 lt-ms. In the second method, we have measured the pulse arrival times at intervals of 100 s over the entire duration of the observation. The pulse arrival time data were used to put an upper limit on any periodic arrival time delay using the Lomb–Scargle periodogram. We have obtained a similar upper limit of 10 lt-ms using the second method over the orbital period range of 500–10,000 s. This puts very stringent upper limits for the mass of the compact object except for the unlikely case of a complete face-on orientation of the binary system with respect to our line-of-sight. In the light of this measurement and the earlier reports, we discuss the possibility of this system being a neutron star with a supernovae fall-back accretion disk.

  9. THE DISK WIND IN THE RAPIDLY SPINNING STELLAR-MASS BLACK HOLE 4U 1630–472 OBSERVED WITH NuSTAR

    Energy Technology Data Exchange (ETDEWEB)

    King, Ashley L.; Miller, Jon M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Walton, Dominic J.; Fürst, Felix; Harrison, Fiona A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Barret, Didier [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); Boggs, Steven E.; Craig, William W.; Krivonos, Roman; Tomsick, John A. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Fabian, Andy C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Hailey, Charles J.; Mori, Kaya [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Natalucci, Lorenzo [Istituto Nazionale di Astrofisica, INAF-IAPS, via del Fosso del Cavaliere, I-00133 Roma (Italy); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-221, Pasadena, CA 91109 (United States); Zhang, William W., E-mail: ashking@umich.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-03-20

    We present an analysis of a short NuSTAR observation of the stellar-mass black hole and low-mass X-ray binary 4U 1630–472. Reflection from the inner accretion disk is clearly detected for the first time in this source, owing to the sensitivity of NuSTAR. With fits to the reflection spectrum, we find evidence for a rapidly spinning black hole, a{sub ∗}=0.985{sub −0.014}{sup +0.005} (1σ statistical errors). However, archival data show that the source has relatively low radio luminosity. Recently claimed relationships between jet power and black hole spin would predict either a lower spin or a higher peak radio luminosity. We also report the clear detection of an absorption feature at 7.03 ± 0.03 keV, likely signaling a disk wind. If this line arises in dense, moderately ionized gas (log ξ=3.6{sub −0.3}{sup +0.2}) and is dominated by He-like Fe XXV, the wind has a velocity of v/c=0.043{sub −0.007}{sup +0.002} (12900{sub −2100}{sup +600} km s{sup –1}). If the line is instead associated with a more highly ionized gas (log ξ=6.1{sub −0.6}{sup +0.7}), and is dominated by Fe XXVI, evidence of a blueshift is only marginal, after taking systematic errors into account. Our analysis suggests the ionized wind may be launched within 200-1100 Rg, and may be magnetically driven.

  10. Kuiper Binary Object Formation

    CERN Document Server

    Nazzario, R C; Covington, C; Kagan, D; Hyde, T W

    2005-01-01

    It has been observed that binary Kuiper Belt Objects (KBOs) exist contrary to theoretical expectations. Their creation presents problems to most current models. However, the inclusion of a third body (for example, one of the outer planets) may provide the conditions necessary for the formation of these objects. The presence of a third massive body not only helps to clear the primordial Kuiper Belt but can also result in long lived binary Kuiper belt objects. The gravitational interaction between the KBOs and the third body causes one of four effects; scattering into the Oort cloud, collisions with the growing protoplanets, formation of binary pairs, or creation of a single Kuiper belt object. Additionally, the initial location of the progenitors of the Kuiper belt objects also has a significant effect on binary formation.

  11. Kilo-hertz QPO in Island State of 4U1608-52 as Observed with RXTE/PCA

    CERN Document Server

    Yu, W; Harmon, B A; Paciesas, W S; Robinson, C R; Grindlay, J E; Bloser, P F; Barret, D; Ford, E C; Tavani, M; Kaaret, P E

    1997-01-01

    We report RXTE/PCA observations of 4U 1608-52 on March 15, 18 and 22 immediately after the outburst in early 1996. The persistent count rates ranged from 190 to 450 cps (1-60 keV). During this period of time, 4U 1608-52 was in the island state. We detected QPO features in the power density spectra (PDS) at 567-800 Hz on March 15 and 22, with source fractional root-mean-square (rms) amplitude of 13%-17% and widths of 78-180 Hz. The average rms amplitude of these QPO features is positively correlated with the energy. Our results imply that the neutron star spin frequency is possibly between 300 Hz and 365 Hz.

  12. Kuiper Binary Object Formation

    OpenAIRE

    Nazzario, R. C.; Orr, K.; Covington, C.; Kagan, D.; Hyde, T. W.

    2005-01-01

    It has been observed that binary Kuiper Belt Objects (KBOs) exist contrary to theoretical expectations. Their creation presents problems to most current models. However, the inclusion of a third body (for example, one of the outer planets) may provide the conditions necessary for the formation of these objects. The presence of a third massive body not only helps to clear the primordial Kuiper Belt but can also result in long lived binary Kuiper belt objects. The gravitational interaction betw...

  13. Eclipsing Binary Pulsars

    CERN Document Server

    Freire, P C C

    2004-01-01

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

  14. Characterizing black hole variability with nonlinear methods: the case of the X-ray Nova 4U 1543-47

    CERN Document Server

    Gliozzi, M; Papadakis, I E; Reig, P

    2009-01-01

    We investigate the possible nonlinear variability properties of the black hole X-ray nova 4U1543-47 to complement the temporal studies based on linear techniques, and to search for signs of nonlinearity in Galactic black hole (GBH) light curves. First, we apply the weighted scaling index method (WSIM) to characterize the X-ray variability properties of 4U1543-47 in different spectral states during the 2002 outburst. Second, we use surrogate data to investigate whether the variability is nonlinear in any of the different spectral states. The main findings can be summarized as follows. The mean weighted scaling index appears to be able to parametrize uniquely the temporal variability properties of this GBH: the 3 different spectral states of the 2002 outburst of 4U1543-47 are characterized by different and well constrained values. The search for nonlinearity reveals that the variability is linear in all light curves with the notable exception of the very high state. Our results imply that we can use the WSIM to...

  15. Observations of the magnetars 4U 0142+61 and 1E 2259+586 with the MAGIC telescopes

    CERN Document Server

    Aleksić, J; Antoranz, P; Asensio, M; de Almeida, U Barres; Barrio, J A; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Boller, A; Bonnefoy, S; Bonnoli, G; Tridon, D Borla; Bretz, T; Carmona, E; Carosi, A; Fidalgo, D Carreto; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Cossio, L; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Mendez, C Delgado; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Eisenacher, D; Elsaesser, D; Ferenc, D; Fonseca, M V; Font, L; Fruck, C; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Giavitto, G; Godinović, N; Muñoz, A González; Gozzini, S R; Hadamek, A; Hadasch, D; Herrero, A; Hose, J; Hrupec, D; Jankowski, F; Kadenius, V; Klepser, S; Knoetig, M L; Krähenbühl, T; Krause, J; Kushida, J; La Barbera, A; Lelas, D; Leonardo, E; Lewandowska, N; Lindfors, E; Lombardi, S; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Masbou, J; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Moldón, J; Moralejo, A; Munar-Adrover, P; Nakajima, D; Niedzwiecki, A; Nieto, D; Nilsson, K; Nowak, N; Orito, R; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Partini, S; Persic, M; Pilia, M; Prada, F; Moroni, P G Prada; Prandini, E; Puljak, I; Reichardt, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Rügamer, S; Saggion, A; Saito, K; Saito, T Y; Salvati, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Spiro, S; Stamatescu, V; Stamerra, A; Steinke, B; Storz, J; Sun, S; Surić, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Tibolla, O; Torres, D F; Toyama, T; Treves, A; Uellenbeck, M; Vogler, P; Wagner, R M; Weitzel, Q; Zandanel, F; Zanin, R; Rea, N

    2012-01-01

    Magnetars are an extreme, highly magnetized class of isolated neutron stars whose large X-ray luminosity is believed to be driven by their high magnetic field. In this work we study for the first time the possible very high energy gamma-ray emission above 100 GeV from magnetars, observing the sources 4U 0142+61 and 1E 2259+586. We observed the two sources with atmospheric Cherenkov telescopes in the very high energy range (E > 100 GeV). 4U 0142+61 was observed with the MAGIC I telescope in 2008 for ~25 h and 1E 2259+586 was observed with the MAGIC stereoscopic system in 2010 for ~14 h. The data were analyzed with the standard MAGIC analysis software. Neither magnetar was detected. Upper limits to the differential and integral flux above 200 GeV were computed using the Rolke algorithm. We obtain integral upper limits to the flux of 1.52*10^-12cm^-2 s^-1 and 2.7*10^-12cm^-2 s^-1 with a confidence level of 95% for 4U 0142+61 and 1E 2259+586, respectively. The resulting differential upper limits are presented tog...

  16. Proper Motions and Origins of AXP 1E 2259+586 and AXP 4U 0142+61

    Science.gov (United States)

    Tendulkar, Shriharsh P.; Cameron, P. Brian; Kulkarni, Shrinivas R.

    2013-07-01

    Using high-resolution NIR images supported by laser guide star adaptive optics from the Keck II telescope from 2005 to 2012, we have measured the proper motions of two anomalous X-ray pulsars, AXP 1E 2259+586 and AXP 4U 0142+61. The proper motion of AXP 1E 2259+586 in the sky frame is (μα, μδ) = (- 6.4 ± 0.6, -2.3 ± 0.6) mas yr-1 and that of AXP 4U 0142+61 is (μα, μδ) = (- 4.1 ± 1, 1.9 ± 1) mas yr-1. After correcting for the velocity of the progenitors, we calculate the tangential ejection velocities of the magnetars to be 157 ± 17 km s-1 and 102 ± 26 km s-1 respectively. The proper motion vector of AXP 1E 2259+586 is directed away from the putative center of the supernova remnant CTB 109 that has long been proposed to be associated with AXP 1E 2259+586. This is significant evidence for linking the pulsar with CTB 109. We comment on the possible movement of CTB 109 after the explosion. We narrow the search cone for the birthsite or remnant of AXP 4U 0142+61 to an opening angle of 24°. However, we are unable to find any suitable association.

  17. A delayed transition to the hard state for 4U 1630-47 at the end of its 2010 outburst

    Energy Technology Data Exchange (ETDEWEB)

    Tomsick, John A. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Yamaoka, Kazutaka [Solar-Terrestrial Environment Laboratory, Department of Particles and Astronomy, Nagoya University, Furocho, Chikusa-ku, Nagoya, Aichi 464-8601 (Japan); Corbel, Stephane [AIM - Unité Mixte de Recherche CEA - CNRS - Université Paris VII - UMR 7158, CEA-Saclay, Service d' Astrophysique, F-91191 Gif-sur-Yvette Cedex (France); Kalemci, Emrah [Sabanci University, Orhanli-Tuzla, Istanbul 34956 (Turkey); Migliari, Simone [Department d' Astronomia i Meteorologia, Universitat de Barcelona, Marti I Franques 1, E-08028 Barcelona (Spain); Kaaret, Philip, E-mail: jtomsick@ssl.berkeley.edu [Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242 (United States)

    2014-08-10

    Here we report on Swift and Suzaku observations near the end of an outburst from the black hole transient 4U 1630-47 and Chandra observations when the source was in quiescence. 4U 1630-47 made a transition from a soft state to the hard state ∼50 days after the main outburst ended. During this unusual delay, the flux continued to drop, and one Swift measurement found the source with a soft spectrum at a 2-10 keV luminosity of L = 1.07 × 10{sup 35} erg s{sup –1} for an estimated distance of 10 kpc. While such transients usually make a transition to the hard state at L/L{sub Edd} = 0.3%-3%, where L{sub Edd} is the Eddington luminosity, the 4U 1630-47 spectrum remained soft at L/L{sub Edd} = 0.008 M{sub 10}{sup −1}% (as measured in the 2-10 keV band), where M{sub 10} is the mass of the black hole in units of 10 M{sub ☉}. An estimate of the luminosity in the broader 0.5-200 keV bandpass gives L/L{sub Edd} = 0.03 M{sub 10}{sup −1}%, which is still an order of magnitude lower than typical. We also measured an exponential decay of the X-ray flux in the hard state with an e-folding time of 3.39 ± 0.06 days, which is much less than previous measurements of 12-15 days during decays by 4U 1630-47 in the soft state. With the ∼100 ks Suzaku observation, we do not see evidence for a reflection component, and the 90% confidence limits on the equivalent width of a narrow iron Kα emission line are <40 eV for a narrow line and <100 eV for a line of any width, which is consistent with a change of geometry (either a truncated accretion disk or a change in the location of the hard X-ray source) in the hard state. Finally, we report a 0.5-8 keV luminosity upper limit of <2 × 10{sup 32} erg s{sup –1} in quiescence, which is the lowest value measured for 4U 1630-47 to date.

  18. Binary Masking & Speech Intelligibility

    DEFF Research Database (Denmark)

    Boldt, Jesper

    The purpose of this thesis is to examine how binary masking can be used to increase intelligibility in situations where hearing impaired listeners have difficulties understanding what is being said. The major part of the experiments carried out in this thesis can be categorized as either experime...... mask using a directional system and a method for correcting errors in the target binary mask. The last part of the thesis, proposes a new method for objective evaluation of speech intelligibility.......The purpose of this thesis is to examine how binary masking can be used to increase intelligibility in situations where hearing impaired listeners have difficulties understanding what is being said. The major part of the experiments carried out in this thesis can be categorized as either...... experiments under ideal conditions or as experiments under more realistic conditions useful for real-life applications such as hearing aids. In the experiments under ideal conditions, the previously defined ideal binary mask is evaluated using hearing impaired listeners, and a novel binary mask -- the target...

  19. Skewed Binary Search Trees

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Moruz, Gabriel

    2006-01-01

    It is well-known that to minimize the number of comparisons a binary search tree should be perfectly balanced. Previous work has shown that a dominating factor over the running time for a search is the number of cache faults performed, and that an appropriate memory layout of a binary search tree...... can reduce the number of cache faults by several hundred percent. Motivated by the fact that during a search branching to the left or right at a node does not necessarily have the same cost, e.g. because of branch prediction schemes, we in this paper study the class of skewed binary search trees....... For all nodes in a skewed binary search tree the ratio between the size of the left subtree and the size of the tree is a fixed constant (a ratio of 1/2 gives perfect balanced trees). In this paper we present an experimental study of various memory layouts of static skewed binary search trees, where each...

  20. Binary Neutron Star Mergers

    Directory of Open Access Journals (Sweden)

    Joshua A. Faber

    2012-07-01

    Full Text Available We review the current status of studies of the coalescence of binary neutron star systems. We begin with a discussion of the formation channels of merging binaries and we discuss the most recent theoretical predictions for merger rates. Next, we turn to the quasi-equilibrium formalisms that are used to study binaries prior to the merger phase and to generate initial data for fully dynamical simulations. The quasi-equilibrium approximation has played a key role in developing our understanding of the physics of binary coalescence and, in particular, of the orbital instability processes that can drive binaries to merger at the end of their lifetimes. We then turn to the numerical techniques used in dynamical simulations, including relativistic formalisms, (magneto-hydrodynamics, gravitational-wave extraction techniques, and nuclear microphysics treatments. This is followed by a summary of the simulations performed across the field to date, including the most recent results from both fully relativistic and microphysically detailed simulations. Finally, we discuss the likely directions for the field as we transition from the first to the second generation of gravitational-wave interferometers and while supercomputers reach the petascale frontier.

  1. 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.

  2. Binary Popldation Synthcsis Study

    Institute of Scientific and Technical Information of China (English)

    HAN Zhanwen

    2011-01-01

    Binary population synthesis (BPS), an approach to evolving millions of stars (including binaries) simultaneously, plays a crucial role in our understanding of stellar physics, the structure and evolution of galaxies, and cosmology. We proposed and developed a BPS approach, and used it to investigate the formation of many peculiar stars such as hot subdwarf stars, progenitors of type la supernovae, barium stars, CH stars, planetary nebulae, double white dwarfs, blue stragglers, contact binaries, etc. We also established an evolution population synthesis (EPS) model, the Yunnan Model, which takes into account binary interactions for the first time. We applied our model for the origin of hot subdwarf stars in the study of elliptical galaxies and explained their far-UV radiation.

  3. No Anticorrelation between Cyclotron Line Energy and X-ray Flux in 4U 0115+634

    Science.gov (United States)

    2013-01-01

    University of California, San Diego, La Jolla, CA 92093, USA 10 Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías, University of...abundances by Wilms et al. (2000) and cross sections by Verner & Yakovlev (1995). We furthermore ac- count for an intrinsic Fe Kα fluorescence line, which...equivalent width WFe. Assuming a narrow line is justified be- cause in systems like 4U 0115+63 Fe Kα is expected to have a width on the order of 0.5 keV (see

  4. ASCA and BeppoSAX observations of the peculiar X-ray source 4U1700+24/HD154791

    CERN Document Server

    Dal Fiume, D; Bartolini, C; Del Sordo, S; Frontera, F; Guarnieri, A; Orlandini, M; Palazzi, E; Parmar, A N; Piccioni, A; Santangelo, A; Segreto, A

    2000-01-01

    The X-ray source 4U1700+24/HD154791 is one of the few galactic sources whosecounterpart is an evolved M star. In X-rays the source shows extreme erraticvariability and a complex and variable spectrum. While this strongly suggestsaccretion onto a compact object, no clear diagnosis of binarity was done up tonow. We report on ASCA and BeppoSAX X-ray broad band observations of thissource and on ground optical observations from the Loiano 1.5 m telescope.

  5. Eclipsing Binary Update, No. 2.

    Science.gov (United States)

    Williams, D. B.

    1996-01-01

    Contents: 1. Wrong again! The elusive period of DHK 41. 2. Stars observed and not observed. 3. Eclipsing binary chart information. 4. Eclipsing binary news and notes. 5. A note on SS Arietis. 6. Featured star: TX Ursae Majoris.

  6. High-resolution X-ray spectroscopy of the ultracompact LMXB pulsar 4U 1626-67

    CERN Document Server

    Krauss, M I; Chakraborty, D; Juett, A M; Cottam, J; Krauss, Miriam I.; Schulz, Norbert S.; Chakrabarty, Deepto; Juett, Adrienne M.; Cottam, Jean

    2006-01-01

    [abridged] We report results from four recent observations of the ultracompact LMXB pulsar 4U 1626-67. All the observations obtained high-resolution X-ray spectra of the system, two from the Chandra X-ray Observatory using the HETGS, and two from the XMM-Newton Observatory using the RGS as well as the EPIC PN and MOS. These data allow us to study in detail the prominent Ne and O emission line complexes which make 4U 1626-67 unique among LMXBs. The observations were spaced over a period of 3 years for a total observing time of 238 ks, allowing us to monitor the line regions as well as the overall source flux, continuum spectrum, and timing properties. The structure of the emission lines and the ratios of the components of the helium-like Ne IX and O VII triplets support the hypothesis that they are formed in the high-density environment of the accretion disk. We do not find any significant changes in the line widths or ratios over this time period, though we note that the line equivalent widths decrease. We ar...

  7. Detection of Highly Ionized Metal Absorption Lines in the Ultracompact X-ray Dipper 4U 1916-05

    CERN Document Server

    Juett, A M; Juett, Adrienne M.; Chakrabarty, Deepto

    2006-01-01

    We present the high-resolution Chandra X-ray Observatory persistent (non-dip) spectrum of 4U 1916-05 which revealed narrow absorption lines from hydrogenic neon, magnesium, silicon, and sulfur, in addition to the previous identified hydrogenic and helium-like iron absorption lines. This makes 4U 1916-05 only the second of the classical X-ray dipper systems to show narrow absorption lines from elements other than iron. We propose two possible explanations for the small measured line widths (>~ 500-2000 km s^{-1}), compared to the expected Keplerian velocities (> 1000 km s^{-1}) of the accretion disk in this 50-min orbital period system, and lack of wavelength shifts (>~ 250 km s^{-1}). First, the ionized absorber may be stationary. Alternatively, the line properties may measure the relative size of the emission region. From this hypothesis, we find that the emission region is constrained to be >~ 0.25 times the radial extent of the absorber. Our results also imply that the ionized absorber spans a range of ion...

  8. Phase-resolved NuSTAR and Swift-XRT Observations of Magnetar 4U 0142+61

    CERN Document Server

    Tendulkar, Shriharsh P; Yang, Chengwei; Kaspi, Victoria M; Beloborodov, Andrei M; An, Hongjun; Bachetti, Matteo; Boggs, Steven E; Christensen, Finn E; Craig, William W; Guillot, Sebastien; Hailey, Charles A; Harrison, Fiona A; Stern, Daniel; Zhang, William

    2015-01-01

    We present temporal and spectral analysis of simultaneous 0.5-79 keV Swift-XRT and NuSTAR observations of the magnetar 4U 0142+61. The pulse profile changes significantly with photon energy between 3 and 35 keV. The pulse fraction increases with energy, reaching a value of ~20%, similar to that observed in 1E 1841-045 and much lower than the ~80% pulse fraction observed in 1E 2259+586. We do not detect the 55-ks phase modulation reported in previous Suzaku-HXD observations. The phase-averaged spectrum of 4U 0142+61 above 20 keV is dominated by a hard power law with a photon index, $\\Gamma$ ~ 0.65, and the spectrum below 20 keV can be described by two blackbodies, a blackbody plus a soft power law, or by a Comptonized blackbody model. We study the full phase-resolved spectra using the electron-positron outflow model of Beloborodov (2013). Our results are consistent with the parameters of the active j-bundle derived from INTEGRAL data by Hascoet et al. (2014). We find that a significant degeneracy appears in th...

  9. Possible hard X-ray shortages in bursts from KS 1731-260 and 4U 1705-44

    CERN Document Server

    Ji, Long; Chen, YuPeng; Zhang, Shuang-Nan; Kretschmar, Peter; Wang, Jian-Min; Li, Jian

    2014-01-01

    Aims: A hard X-ray shortage, implying the cooling of the corona, was observed during bursts of IGR J17473-272, 4U 1636-536, Aql X-1, and GS 1826-238. Apart from these four sources, we investigate here an atoll sample, in which the number of bursts for each source is larger than 5, to explore the possible additional hard X-ray shortage during {\\it Rossi X-ray timing explorer (RXTE)} era. Methods: According to the source catalog that shows type-I bursts, we analyzed all the available pointing observations of these sources carried out by the {\\it RXTE} proportional counter array (PCA). We grouped and combined the bursts according to their outburst states and searched for the possible hard X-ray shortage while bursting. Results: We found that the island states of KS 1731-260 and 4U 1705-44 show a hard X-ray shortage at significant levels of 4.5 and 4.7 $\\sigma$ and a systematic time lag of $0.9 \\pm 2.1$ s and $2.5 \\pm 2.0$ s with respect to the soft X-rays, respectively. While in their banana branches and other s...

  10. Millihertz quasi-periodic oscillations in 4U 1636-53 associated with bursts with positive convexity only

    CERN Document Server

    Lyu, Ming; Altamirano, Diego; Zhang, Guobao

    2016-01-01

    We investigated the convexity of all type I X-ray bursts with millihertz quasi-periodic oscillations (mHz QPOs) in 4U 1636-53 using archival observations with the Rossi X-ray Timing Explorer. We found that, at a 3.5 $\\sigma$ confidence level, in all 39 cases in which the mHz QPOs disappeared at the time of an X-ray burst, the convexity of the burst is positive. The convexity measures the shape of the rising part of the burst light curve and, according to recent models, it is related to the ignition site of bursts on the neutron star surface. This finding suggests that in 4U 1636-53 these 39 bursts and the marginally-stable nuclear burning process responsible for the mHz QPOs take place at the neutron-star equator. This scenario could explain the inconsistency between the high accretion rate required for triggering mHz QPOs in theoretical models and the relatively low accretion rate derived from observations.

  11. Evolution of cross-correlation and time lag of 4U 1735-44 along the branches

    CERN Document Server

    Lei, Ya-Juan; Zhang, Cheng-Min; Qu, Jin-Lu; Yuan, Hai-Long; Dong, Yi-Qiao; Zhao, Yong-Heng; Wang, De-Hua; Yin, Hong-Xing; Song, Li-Ming

    2013-01-01

    We analyze the cross-correlation function between the soft and hard X-rays of atoll source 4U 1735-44 with RXTE data, and find the anti-correlated soft and hard time lags of about hecto-second. On the island state, the observations do not show any obvious correlations, and most observations of banana branch show positive correlation. However, the anti-correlations are detected on the upper banana branch. These results are different from those of Z sources (Cyg X-2, GX 5-1), where the anti-correlation is detected in the low luminosity states, then the lag timescales of both this atoll and Z sources are found to be similar, at the magnitude of several tens to hundreds of seconds. As a comparison, it is noted that the anti-correlated lags of thousand-second have been reported from the several black hole candidates in their intermediate states. Finally, we compare the correspondent results of atoll source 4U 1735-44 with those observed in black hole candidates and Z sources, and the possible origins of the anti-c...

  12. Millihertz quasi-periodic oscillations in 4U 1636-53 associated with bursts with positive convexity only

    Science.gov (United States)

    Lyu, Ming; Méndez, Mariano; Altamirano, Diego; Zhang, Guobao

    2016-12-01

    We investigated the convexity of all type I X-ray bursts with millihertz quasi-periodic oscillations (mHz QPOs) in 4U 1636-53 using archival observations with the Rossi X-ray Timing Explorer. We found that, at a 3.5σ confidence level, in all 39 cases in which the mHz QPOs disappeared at the time of an X-ray burst, the convexity of the burst is positive. The convexity measures the shape of the rising part of the burst light curve and, according to recent models, it is related to the ignition site of bursts on the neutron-star surface. This finding suggests that in 4U 1636-53 these 39 bursts and the marginally stable nuclear burning process responsible for the mHz QPOs take place at the neutron-star equator. This scenario could explain the inconsistency between the high accretion rate required for triggering mHz QPOs in theoretical models and the relatively low accretion rate derived from observations.

  13. Millihertz quasi-periodic oscillations always associated with bursts with positive convexity in 4U 1636-53

    Science.gov (United States)

    Lyu, Ming; Mendez, Mariano; Zhang, Guo-Bao; Altamirano, Diego

    2016-07-01

    We investigated the convexity of all type I X-ray bursts with millihertz quasi-periodic oscillations (mHz QPOs) in 4U 1636-53 using archival observations with the Rossi X-ray Timing Explorer. We found that all 39 mHz QPOs disappeared at the time of an X-ray burst, the convexity of the burst is positive. The convexity measures the shape of the rising part of the burst light curve and, according to recent models, it is related to the ignition site of bursts on the neutron-star surface. This finding suggests that in 4U 1636-53 these 39 bursts and the marginally-stable nuclear burning process responsible for the mHz QPOs take place at the neutron-star equator. This scenario would explain the inconsistency between the high accretion rate required for triggering mHz QPOs in theoretical models and the relatively low accretion rate derived from observations.

  14. X-ray and optical monitoring of the peculiar source 4U 1700+24/V934 Her

    CERN Document Server

    Masetti, N; Cusumano, G; Amati, L; Bartolini, C; Del Sordo, S; Frontera, F; Guarnieri, A; Orlandini, M; Palazzi, E; Parmar, A N; Piccioni, A; Santangelo, A

    2002-01-01

    (Abridged) We report on ASCA and BeppoSAX observations of the X-ray source 4U 1700+24 and on (quasi-)simultaneous spectroscopy of its optical counterpart, V934 Her, from the Loiano 1.5-meter telescope. Archival ROSAT and RXTE data as well as the RXTE ASM light curve of 4U 1700+24 are also analyzed along with a 1985 EXOSAT pointing. The optical spectra are typical of a M2 III star; a revised distance to the object of ~400 pc is inferred. While these spectra do not show either any change between the two epochs or any peculiar feature, the X-ray spectra reveal a complex and long-term variable shape, with a clear soft excess. The X-ray spectral properties of the source are best described by a thermal Comptonization spectrum plus a soft energy(<1 keV) excess, which can be modeled with a blackbody emission with kT_BB ~ 1 keV; the latter component is not detected at the lowest source flux levels. The ratio between the two components varies substantially with the source flux. The X-ray emission from the object app...

  15. Propeller effect in two brightest transient X-ray pulsars: 4U 0115+63 and V 0332+53

    CERN Document Server

    Tsygankov, S S; Doroshenko, V; Mushtukov, A A; Poutanen, J

    2016-01-01

    We present the results of the monitoring programmes performed with the Swift/XRT telescope and aimed specifically to the detection of an abrupt decrease of the observed flux associated with a transition to the propeller regime in two well known X-ray pulsars 4U 0115+63 and V 0332+53 during their giant outbursts in 2015. Such transitions were detected at the threshold luminosities of $(1.4\\pm0.4)\\times10^{36}$ erg s$^{-1}$ and $(2.0\\pm0.4)\\times10^{36}$ erg s$^{-1}$ for 4U 0115+63 and V 0332+53, respectively. Spectra of the sources are shown to be significantly softer during the low state. In both sources, the accretion at rates close to the aforementioned threshold values briefly resumes during the periastron passage following the transition into propeller regime. The strength of the dipole component of the magnetic field required to inhibit the accretion agrees well with estimates based on the position of the cyclotron lines in their spectra, thus excluding presence of a strong multipole component of the mag...

  16. The High Energy X-ray Spectrum of 4U1700-37 Observed from OSO-8

    Science.gov (United States)

    Dolan, J. F.; Coe, M. J.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Maurer, G. S.; Orwig, L. E.

    1979-01-01

    The most intense hard X-ray source in the confused region in Scorpius is identified as 4U1700-37. The 3.4-day modulation is seen above 20 keV with the intensity during eclipse being consistent with zero flux. The photon-number spectrum from 20 to 150 keV is well represented by a single power law with a photo-number spectral index of -2.77 + or - 0.35 or by a thermal bremsstrahlung spectrum with kT = 27 96.8-min X-ray modulation previously reported at lower energies. Despite the difficulties in reconciling both the lack of periodic modulation in the emitted X-radiation and the orbital dynamics of the system with theories of the evolution and physical properties of neutron stars, the observed properties of 4U1700-37 are all consistent with the source being a spherically accreting neutron star rather than a black hole.

  17. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Hansen, Esben Rune; Satti, Srinivasa Rao; Tiedemann, Peter

    2008-01-01

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1...

  18. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Rune Hansen, Esben; Srinivasa Rao, S.; Tiedemann, Peter

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1...

  19. Orbits for sixteen binaries

    Directory of Open Access Journals (Sweden)

    Cvetković Z.

    2006-01-01

    Full Text Available In this paper orbits for 13 binaries are recalculated and presented. The reason is that recent observations show higher residuals than the corresponding ephemerides calculated by using the orbital elements given in the Sixth Catalog of Orbits of Visual Binary Stars. The binaries studied were: WDS 00182+7257 = A 803, WDS 00335+4006 = HO 3, WDS 00583+2124 = BU 302, WDS 01011+6022 = A 926, WDS 01014+1155 = BU 867, WDS 01112+4113 = A 655, WDS 01361−2954 + HJ 3447, WDS 02333+5219 = STT 42 AB,WDS 04362+0814 = A 1840 AB,WDS 08017−0836 = A 1580, WDS 08277−0425 = A 550, WDS 17471+1742 = STF 2215 and WDS 18025+4414 = BU 1127 Aa-B. In addition, for three binaries - WDS 01532+1526 = BU 260, WDS 02563+7253 = STF 312 AB and WDS 05003+3924 = STT 92 AB - the orbital elements are calculated for the first time. In this paper the authors present not only the orbital elements, but the masses dynamical parallaxes, absolute magnitudes and ephemerides for the next five years, as well.

  20. Equational binary decision diagrams

    NARCIS (Netherlands)

    Groote, J.F.; Pol, J.C. van de

    2000-01-01

    We incorporate equations in binary decision diagrams (BDD). The resulting objects are called EQ-BDDs. A straightforward notion of ordered EQ-BDDs (EQ-OBDD) is defined, and it is proved that each EQ-BDD is logically equivalent to an EQ-OBDD. Moreover, on EQ-OBDDs satisfiability and tautology checkin

  1. Black holes in binary stars

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1996-01-01

    Introduction Distinguishing neutron stars and black holes Optical companions and dynamical masses X-ray signatures of the nature of a compact object Structure and evolution of black-hole binaries High-mass black-hole binaries Low-mass black-hole binaries Low-mass black holes Formation of black holes

  2. Learning to assign binary weights to binary descriptor

    Science.gov (United States)

    Huang, Zhoudi; Wei, Zhenzhong; Zhang, Guangjun

    2016-10-01

    Constructing robust binary local feature descriptors are receiving increasing interest due to their binary nature, which can enable fast processing while requiring significantly less memory than their floating-point competitors. To bridge the performance gap between the binary and floating-point descriptors without increasing the computational cost of computing and matching, optimal binary weights are learning to assign to binary descriptor for considering each bit might contribute differently to the distinctiveness and robustness. Technically, a large-scale regularized optimization method is applied to learn float weights for each bit of the binary descriptor. Furthermore, binary approximation for the float weights is performed by utilizing an efficient alternatively greedy strategy, which can significantly improve the discriminative power while preserve fast matching advantage. Extensive experimental results on two challenging datasets (Brown dataset and Oxford dataset) demonstrate the effectiveness and efficiency of the proposed method.

  3. Population Synthesis for Symbiotic X-ray Binaries

    CERN Document Server

    Lu, G -L; Postnov, K A; Yungelson, L R; Kuranov, A G; Wang, N

    2012-01-01

    Symbiotic X-ray binaries (SyXBs) comprise a rare class of low-mass X-ray binaries. We study the Galactic SyXBs, which we consider as detached binaries composed of low-mass giants and wind-fed neutron star companions, by simulation of the interaction of a magnetized neutron star (NS) with its environment and utilizing a population synthesis code. We focus mainly on the parameters that influence observational appearance of the SyXB: the donor wind velocity (vw) and the angular momentum distribution in the shell of matter settling onto NS. We estimate the birthrate of SyXB as $\\sim 4.1\\times 10^{-5}$ yr$^{-1}$ to $ \\sim 6.6\\times 10^{-6}$ yr$^{-1}$ and their number in the Galaxy as $\\sim$(100 -- 1000). Assumed stellar wind velocity from cool giants is the input parameter that influences the model SyXBs population most. Among known SyXBs or candidate systems, 4U 1954+31 and IGR J16358-4724 in which NS have very long spin periods may host quasi-spherically accreting NSs. GX 1+4 has a peculiar long-term spin behavi...

  4. A state-dependent influence of the type-I bursts on the accretion in 4U 1608--52?

    CERN Document Server

    Ji, Long; Chen, YuPeng; Zhang, Shuang-Nan; Torres, Diego F; Kretschmar, Peter; Li, Jian

    2014-01-01

    We investigated the possible feedback of type-I burst to the accretion process during the spectral evolution of the atoll source 4U 1608--52. By fitting the burst spectrum with a blackbody and an adjustable, persistent spectral component, we found that the latter is significant state-dependent. In the banana state the persistent flux increases along the burst evolution, while in the island state this trend holds only when the bursts are less luminous and starts to reverse at higher burst luminosities. We speculate that, by taking into account both the Poynting-Robertson drag and radiation pressure, these phenomena may arise from the interactions between the radiation field of the type-I burst and the inner region of the accretion disc.

  5. Possible evidence for free precession of a strongly magnetized neutron star in the magnetar 4U 0142+61.

    Science.gov (United States)

    Makishima, K; Enoto, T; Hiraga, J S; Nakano, T; Nakazawa, K; Sakurai, S; Sasano, M; Murakami, H

    2014-05-01

    Magnetars are a special type of neutron stars, considered to have extreme dipole magnetic fields reaching ∼ 10(11) T. The magnetar 4 U 0142+61, one of the prototypes of this class, was studied in broadband x rays (0.5-70 keV) with the Suzaku observatory. In hard x rays (15-40 keV), its 8.69 sec pulsations suffered slow phase modulations by ± 0.7 sec, with a period of ∼ 15 h. When this effect is interpreted as free precession of the neutron star, the object is inferred to deviate from spherical symmetry by ∼ 1.6 × 10(-4) in its moments of inertia. This deformation, when ascribed to magnetic pressure, suggests a strong toroidal magnetic field, ∼ 10(12) T, residing inside the object. This provides one of the first observational approaches towards toroidal magnetic fields of magnetars.

  6. Possible Evidence for Free Precession of a Strongly Magnetized Neutron Star in the Magnetar 4U 0142+61

    CERN Document Server

    Makishima, Kazuo; Hiraga, Junko S; Nakano, Toshio; Nakazawa, Kazuhiro; Sakurai, Soki; Sasano, Makoto; Murakami, Hiroaki

    2014-01-01

    Magnetars are a special type of neutron stars, considered to have extreme dipole magnetic fields reaching ~1e+11 T. The magnetar 4U 0142+61, one of prototypes of this class, was studied in broadband X-rays (0.5-70 keV) with the Suzaku observatory. In hard X-rays (15-40 keV), its 8.69 sec pulsations suffered slow phase modulations by +/-0.7 sec, with a period of ~1.5 hours. When this effect is interpreted as free precession of the neutron star, the object is inferred to deviate from spherical symmetry by ~1.6e-4 in its moments of inertia. This deformation, when ascribed to magnetic pressure, suggests a strong toroidal magnetic field, ~1e+12 T, residing inside the object. This provides one of the first observational approaches towards toroidal magnetic fields of magnetars.

  7. The Binary Garrote

    CERN Document Server

    Kappen, H J

    2011-01-01

    In this paper, I present a new model and solution method for sparse regression. The model introduces binary selector variables $s_i$ for the features $i$ in a way that is similar to Breiman's Garrote model. I refer to this method as the binary Garrote (BG). The posterior probability for $s_i$ is computed in the variational approximation. The BG is compared numerically with the Lasso method and with ridge regression. Numerical results on synthetic data show that the BG yields more accurate predictions and more accurately reconstructs the true model than the other methods. The naive implementation of the BG requires the inversion of a modified covariance matrix which scales cubic in the number of features. We indicate how for sparse problem the solution can be computed linear in the number of features.

  8. Binary Tetrahedral Flavor Symmetry

    CERN Document Server

    Eby, David A

    2013-01-01

    A study of the T' Model and its variants utilizing Binary Tetrahedral Flavor Symmetry. We begin with a description of the historical context and motivations for this theory, together with some conceptual background for added clarity, and an account of our theory's inception in previous works. Our model endeavors to bridge two categories of particles, leptons and quarks, a unification made possible by the inclusion of additional Higgs particles, shared between the two fermion sectors and creating a single coherent system. This is achieved through the use of the Binary Tetrahedral symmetry group and an investigation of the Tribimaximal symmetry evidenced by neutrinos. Our work details perturbations and extensions of this T' Model as we apply our framework to neutrino mixing, quark mixing, unification, and dark matter. Where possible, we evaluate model predictions against experimental results and find excellent matching with the atmospheric and reactor neutrino mixing angles, an accurate prediction of the Cabibb...

  9. Binary Love Relations

    CERN Document Server

    Yagi, Kent

    2015-01-01

    When in a tight binary, the mutual tidal deformations of neutron stars imprint onto observables, encoding information about their internal structure at supranuclear densities and gravity in the extreme-gravity regime. Gravitational wave observations of their late binary inspiral may serve as a tool to extract the individual tidal deformabilities, but this is made difficult by degeneracies between them in the gravitational wave model. We here resolve this problem by discovering approximately universal relations between dimensionless combinations of the individual tidal deformabilities. We show that these relations break degeneracies in the gravitational wave model, allowing for the accurate extraction of both deformabilities. Such measurements can be used to better differentiate between equation-of-state models, and improve tests of General Relativity and cosmology.

  10. Binary Love relations

    Science.gov (United States)

    Yagi, Kent; Yunes, Nicolás

    2016-07-01

    When in a tight binary, the mutual tidal deformations of neutron stars get imprinted onto observables, encoding information about their internal structure at supranuclear densities and gravity in the extreme-gravity regime. Gravitational wave (GW) observations of their late binary inspiral may serve as a tool to extract the individual tidal deformabilities, but this is made difficult by degeneracies between them in the GW model. We here resolve this problem by discovering approximately equation-of-state (EoS)-insensitive relations between dimensionless combinations of the individual tidal deformabilities. We show that these relations break degeneracies in the GW model, allowing for the accurate extraction of both deformabilities. Such measurements can be used to better differentiate between EoS models, and improve tests of general relativity and cosmology.

  11. EVOLUTION OF THE CROSS-CORRELATION AND TIME LAG OF 4U 1735-44 ALONG THE BRANCHES

    Energy Technology Data Exchange (ETDEWEB)

    Lei Yajuan; Zhang Haotong; Zhang Chengmin; Yuan Hailong; Dong Yiqiao; Zhao Yongheng; Zhang Yanxia [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Qu Jinlu; Song Liming [Particle Astrophysics Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wang Dehua [Astronomy Department, Beijing Normal University, Beijing 100875 (China); Yin Hongxing, E-mail: leiyjcwmy@163.com [School of Space Science and Physics, Shandong University, Weihai 264209 (China)

    2013-09-15

    We analyze the cross-correlation function between the soft and hard X-rays of atoll source 4U 1735-44 with RXTE data, and find anti-correlated soft and hard time lags of about a hecto-second. In the island state, the observations do not show any obvious correlations, and most observations of the banana branch show a positive correlation. However, anti-correlations are detected in the upper banana branch. These results are different from those of Z-sources (Cyg X-2, GX 5-1), where anti-correlations are detected in the horizontal branch and upper normal branch. In this case, the lag timescales of both this atoll and Z-sources are found to be similar, at a magnitude of several tens to hundreds of seconds. As a comparison, it is noted that anti-correlated lags lasting thousands of seconds have been reported from several black hole candidates in their intermediate states. In addition, for an observation containing four segments that show positive or anti-correlation, we analyze the spectral evolution with the hybrid model. In the observation, the anti-correlation is detected at the highest flux. The fitting results show that the Comptonized component is not the lowest at the highest flux, which suggests that the anti-correlation corresponds to the transition between the soft and hard states. Finally, we compare the corresponding results of atoll source 4U 1735-44 with those observed in Z-sources and black hole candidates, and the possible origins of the anti-correlated time lags are discussed.

  12. A Link Between X-ray Emission Lines and Radio Jets in 4U 1630-47?

    Science.gov (United States)

    Neilsen, Joseph; Coriat, Mickaël; Fender, Rob; Lee, Julia C.; Ponti, Gabriele; Tzioumis, A.; Edwards, Phillip; Broderick, Jess

    2014-06-01

    Recently, Díaz Trigo et al. reported an XMM-Newton detection of relativistically Doppler-shifted emission lines associated with steep-spectrum radio emission in the stellar-mass black hole candidate 4U 1630-47 during its 2012 outburst. They interpreted these lines as indicative of a baryonic jet launched by the accretion disk. We present a search for the same lines earlier in the same outburst using high-resolution X-ray spectra from the Chandra HETGS. While our observations (eight months prior to the XMM-Newton campaign) also coincide with detections of steep spectrum radio emission by the Australia Telescope Compact Array, we find a strong disk wind but no evidence for any relativistic X-ray emission lines. Indeed, despite ˜5× brighter radio emission, our Chandra spectra allow us to place an upper limit on the flux in the blueshifted Fe XXVI line that is ˜20× weaker than the line observed by Díaz Trigo et al. Thus we can conclusively say that radio emission is not universally associated with relativistically Doppler-shifted emission lines in 4U 1630-47. We explore several scenarios that could explain our differing results, including variations in the geometry of the jet or a mass-loading process or jet baryon content that evolves with the accretion state of the black hole. We also consider the possibility that the radio emission arises in an interaction between a jet and the nearby ISM, in which case the X-ray emission lines might be unrelated to the radio emission.

  13. Binary-Signal Recovery

    Science.gov (United States)

    Griebeler, Elmer L.

    2011-01-01

    Binary communication through long cables, opto-isolators, isolating transformers, or repeaters can become distorted in characteristic ways. The usual solution is to slow the communication rate, change to a different method, or improve the communication media. It would help if the characteristic distortions could be accommodated at the receiving end to ease the communication problem. The distortions come from loss of the high-frequency content, which adds slopes to the transitions from ones to zeroes and zeroes to ones. This weakens the definition of the ones and zeroes in the time domain. The other major distortion is the reduction of low frequency, which causes the voltage that defines the ones or zeroes to drift out of recognizable range. This development describes a method for recovering a binary data stream from a signal that has been subjected to a loss of both higher-frequency content and low-frequency content that is essential to define the difference between ones and zeroes. The method makes use of the frequency structure of the waveform created by the data stream, and then enhances the characteristics related to the data to reconstruct the binary switching pattern. A major issue is simplicity. The approach taken here is to take the first derivative of the signal and then feed it to a hysteresis switch. This is equivalent in practice to using a non-resonant band pass filter feeding a Schmitt trigger. Obviously, the derivative signal needs to be offset to halfway between the thresholds of the hysteresis switch, and amplified so that the derivatives reliably exceed the thresholds. A transition from a zero to a one is the most substantial, fastest plus movement of voltage, and therefore will create the largest plus first derivative pulse. Since the quiet state of the derivative is sitting between the hysteresis thresholds, the plus pulse exceeds the plus threshold, switching the hysteresis switch plus, which re-establishes the data zero to one transition

  14. Massive Black Hole Binary Evolution

    Directory of Open Access Journals (Sweden)

    Merritt David

    2005-11-01

    Full Text Available Coalescence of binary supermassive black holes (SBHs would constitute the strongest sources of gravitational waves to be observed by LISA. While the formation of binary SBHs during galaxy mergers is almost inevitable, coalescence requires that the separation between binary components first drop by a few orders of magnitude, due presumably to interaction of the binary with stars and gas in a galactic nucleus. This article reviews the observational evidence for binary SBHs and discusses how they would evolve. No completely convincing case of a bound, binary SBH has yet been found, although a handful of systems (e.g. interacting galaxies; remnants of galaxy mergers are now believed to contain two SBHs at projected separations of <~ 1kpc. N-body studies of binary evolution in gas-free galaxies have reached large enough particle numbers to reproduce the slow, “diffusive” refilling of the binary’s loss cone that is believed to characterize binary evolution in real galactic nuclei. While some of the results of these simulations - e.g. the binary hardening rate and eccentricity evolution - are strongly N-dependent, others - e.g. the “damage” inflicted by the binary on the nucleus - are not. Luminous early-type galaxies often exhibit depleted cores with masses of ~ 1-2 times the mass of their nuclear SBHs, consistent with the predictions of the binary model. Studies of the interaction of massive binaries with gas are still in their infancy, although much progress is expected in the near future. Binary coalescence has a large influence on the spins of SBHs, even for mass ratios as extreme as 10:1, and evidence of spin-flips may have been observed.

  15. Chandra Observations of the Faintest Low-Mass X-ray Binaries

    CERN Document Server

    Wilson, C A; Kouveliotou, C; Jonker, P G; Van der Klis, M; Lewin, W H G; Belloni, T; Méndez, M; Wilson, Colleen. A.; Patel, Sandeep K.; Kouveliotou, Chryssa; Jonker, Peter G.; Klis, Michiel van der; Lewin, Walter H.G; Belloni, Tomaso; Mendez, Mariano

    2003-01-01

    There exists a group of persistently faint galactic X-ray sources that, based on their location in the galaxy, high L_x/L_opt, association with X-ray bursts, and absence of low frequency X-ray pulsations, are thought to be low-mass X-ray binaries (LMXBs). We present results from Chandra observations for eight of these systems: 4U 1708-408, 2S 1711-339, KS 1739-304, SLX 1735-269, GRS 1736-297, SLX 1746-331, 1E 1746.7-3224, and 4U 1812-12. Locations for all sources, excluding GRS 1736-297, SLX 1746-331, and KS 1739-304 (which were not detected) were improved to 0.6" error circles (90% confidence). Our observations support earlier findings of transient behavior of GRS 1736-297, KS 1739-304, SLX 1746-331, and 2S 1711-339 (which we detect in one of two observations). Energy spectra for 4U 1708-408, 2S 1711-339, SLX 1735-269, 1E 1746.7-3224, and 4U 1812-12 are hard, with power law indices typically 1.4-2.1, which are consistent with typical faint LMXB spectra.

  16. Visual binary stars: data to investigate formation of binaries

    Science.gov (United States)

    Kovaleva,, D.; Malkov,, O.; Yungelson, L.; Chulkov, D.

    Statistics of orbital parameters of binary stars as well as statistics of their physical characteristics bear traces of star formation history. However, statistical investigations of binaries are complicated by incomplete or missing observational data and by a number of observational selection effects. Visual binaries are the most common type of observed binary stars, with the number of pairs exceeding 130 000. The most complete list of presently known visual binary stars was compiled by cross-matching objects and combining data of the three largest catalogues of visual binaries. This list was supplemented by the data on parallaxes, multicolor photometry, and spectral characteristics taken from other catalogues. This allowed us to compensate partly for the lack of observational data for these objects. The combined data allowed us to check the validity of observational values and to investigate statistics of the orbital and physical parameters of visual binaries. Corrections for incompleteness of observational data are discussed. The datasets obtained, together with modern distributions of binary parameters, will be used to reconstruct the initial distributions and parameters of the function of star formation for binary systems.

  17. The Magneto Hydro Dynamical Model of KHz Quasi Periodic Oscillations in Neutron Star Low Mass X-ray Binaries (II)

    CERN Document Server

    Shi, Chang-Sheng; Li, Xiang-Dong

    2014-01-01

    We study the kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low mass X-ray binaries (LMXBs) with a new magnetohydrodynamics (MHD) model, in which the compressed magnetosphere is considered. The previous MHD model (Shi \\& Li 2009) is re-examined and the relation between the frequencies of the kHz QPOs and the accretion rate in LMXBs is obtained. Our result agrees with the observations of six sources (4U 0614+09, 4U 1636--53, 4U 1608--52, 4U 1915--15, 4U 1728--34, XTE 1807--294) with measured spins. In this model the kHz QPOs originate from the MHD waves in the compressed magnetosphere. The single kHz QPOs and twin kHz QPOs are produced in two different parts of the accretion disk and the boundary is close to the corotation radius. The lower QPO frequency in a frequency-accretion rate diagram is cut off at low accretion rate and the twin kHz QPOs encounter a top ceiling at high accretion rate due to the restriction of innermost stable circular orbit.

  18. Rotational mixing in close binaries

    CERN Document Server

    de Mink, S E; Langer, N; Yoon, S -Ch; Brott, I; Glebbeek, E; Verkoulen, M; Pols, O R

    2008-01-01

    Rotational mixing is a very important but uncertain process in the evolution of massive stars. We propose to use close binaries to test its efficiency. Based on rotating single stellar models we predict nitrogen surface enhancements for tidally locked binaries. Furthermore we demonstrate the possibility of a new evolutionary scenario for very massive (M > 40 solar mass) close (P < 3 days) binaries: Case M, in which mixing is so efficient that the stars evolve quasi-chemically homogeneously, stay compact and avoid any Roche-lobe overflow, leading to very close (double) WR binaries.

  19. Evolution of Close Binary Systems

    Energy Technology Data Exchange (ETDEWEB)

    Yakut, K; Eggleton, P

    2005-01-24

    We collected data on the masses, radii, etc. of three classes of close binary stars: low-temperature contact binaries (LTCBs), near-contact binaries (NCBs), and detached close binaries (DCBs). They restrict themselves to systems where (1) both components are, at least arguably, near the Main Sequence, (2) the periods are less than a day, and (3) there is both spectroscopic and photometric analysis leading to reasonably reliable data. They discuss the possible evolutionary connections between these three classes, emphasizing the roles played by mass loss and angular momentum loss in rapidly-rotating cool stars.

  20. Chaos in Binary Category Computation

    CERN Document Server

    Gonçalves, Carlos Pedro

    2010-01-01

    Category computation theory deals with a web-based systemic processing that underlies the morphic webs, which constitute the basis of categorial logical calculus. It is proven that, for these structures, algorithmically incompressible binary patterns can be morphically compressed, with respect to the local connectivities, in a binary morphic program. From the local connectivites, there emerges a global morphic connection that can be characterized by a low length binary string, leading to the identification of chaotic categorial dynamics, underlying the algorithmically random pattern. The work focuses on infinite binary chains of C2, which is a category that implements an X-OR-based categorial logical calculus.

  1. Low autocorrelation binary sequences

    Science.gov (United States)

    Packebusch, Tom; Mertens, Stephan

    2016-04-01

    Binary sequences with minimal autocorrelations have applications in communication engineering, mathematics and computer science. In statistical physics they appear as groundstates of the Bernasconi model. Finding these sequences is a notoriously hard problem, that so far can be solved only by exhaustive search. We review recent algorithms and present a new algorithm that finds optimal sequences of length N in time O(N {1.73}N). We computed all optimal sequences for N≤slant 66 and all optimal skewsymmetric sequences for N≤slant 119.

  2. Microlensing modulation by binaries

    CERN Document Server

    Dubath, F; Durrer, R; Dubath, Florian; Gasparini, Maria Alice; Durrer, Ruth

    2006-01-01

    We compute the effect of the lens quadrupole on microlensing. The time dependence of the quadrupole can lead to specific modulations of the amplification signal. We study especially binary system lenses in our galaxy. The modulation is observable if the rotation period of the system is smaller than the time over which the amplification is significant and if the impact parameter of the passing light ray is sufficiently close to the Einstein radius so that the amplification is very large. Observations of this modulation can reveal important information on the quadrupole and thus on the gravitational radiation emitted by the lens.

  3. In vivo kinetics of U4/U6·U5 tri-snRNP formation in Cajal bodies.

    Science.gov (United States)

    Novotný, Ivan; Blažíková, Michaela; Staněk, David; Herman, Petr; Malinsky, Jan

    2011-02-15

    The U4/U6·U5 tri-small nuclear ribonucleoprotein particle (tri-snRNP) is an essential pre-mRNA splicing factor, which is assembled in a stepwise manner before each round of splicing. It was previously shown that the tri-snRNP is formed in Cajal bodies (CBs), but little is known about the dynamics of this process. Here we created a mathematical model of tri-snRNP assembly in CBs and used it to fit kinetics of individual snRNPs monitored by fluorescence recovery after photobleaching. A global fitting of all kinetic data determined key reaction constants of tri-snRNP assembly. Our model predicts that the rates of di-snRNP and tri-snRNP assemblies are similar and that ∼230 tri-snRNPs are assembled in one CB per minute. Our analysis further indicates that tri-snRNP assembly is approximately 10-fold faster in CBs than in the surrounding nucleoplasm, which is fully consistent with the importance of CBs for snRNP formation in rapidly developing biological systems. Finally, the model predicted binding between SART3 and a CB component. We tested this prediction by Förster resonance energy transfer and revealed an interaction between SART3 and coilin in CBs.

  4. Cloning and molecular characterization of Trypanosoma cruzi U2, U4, U5, and U6 small nuclear RNAs

    Directory of Open Access Journals (Sweden)

    DL Ambrósio

    2007-02-01

    Full Text Available Small nuclear RNAs (snRNAs are important factors in the functioning of eukaryotic cells that form several small complexes with proteins; these ribonucleoprotein particles (U snRNPs have an essential role in the pre-mRNA processing, particularly in splicing, catalyzed by spliceosomes, large RNA-protein complexes composed of various snRNPs. Even though they are well defined in mammals, snRNPs are still not totally characterized in certain trypanosomatids as Trypanosoma cruzi. For this reason we subjected snRNAs (U2, U4, U5, and U6 from T. cruzi epimastigotes to molecular characterization by polymerase chain reaction (PCR and reverse transcription-PCR. These amplified sequences were cloned, sequenced, and compared with those other of trypanosomatids. Among these snRNAs, U5 was less conserved and U6 the most conserved. Their respective secondary structures were predicted and compared with known T. brucei structures. In addition, the copy number of each snRNA in the T. cruzi genome was characterized by Southern blotting.

  5. The featureless and non-variable optical spectral energy distribution of AXP 4U 0142+61

    Science.gov (United States)

    Muñoz-Darias, T.; de Ugarte Postigo, A.; Casares, J.

    2016-05-01

    We present GTC-10.4 m spectroscopy and multiband photometry of the faint (r ˜ 26) optical counterpart of the anomalous X-ray pulsar 4U 0142+61. The 5000-9000 Å spectrum - the first obtained for a magnetar - is featureless, allowing us to set an equivalent width upper limit EW < 25 Å to the presence of emission lines in the H α region. Multiband photometry in the g, r, i, z Sloan Digital Sky Survey (SDSS) bands obtained at different epochs over 12 yr shows no significant variability from minutes-to-years time-scales. The photometry has been calibrated, for the first time, against the SDSS itself, resulting in solid upper limits to variability ranging from ˜0.2 mag in i (over 12 yr) to 0.05 mag in z (over 1.5 yr). The shape of the optical + near-infrared (literature values) spectral energy distribution is not well constrained due to the high extinction along the line of sight. Using a Markov Chain Monte Carlo analysis, we find that it can be described by a power law with a spectral index β = -0.7 ± 0.5 and E(B - V) = 1.5 ± 0.4. We also discuss on the implications of adding hard X-ray flux values from literature to the spectral fitting.

  6. The first multi-wavelength campaign of AXP 4U 0142+61 from radio to hard X-rays

    CERN Document Server

    Den Hartog, P R; Hermsen, W; Rea, N; Durant, M; Stappers, B; Kaspi, V M; Dib, R

    2006-01-01

    For the first time a quasi-simultaneous multi-wavelength campaign has been performed on an Anomalous X-ray Pulsar from the radio to the hard X-ray band. 4U 0142+61 was an INTEGRAL target for 1 Ms in July 2005. During these observations it was also observed in the X-ray band with Swift and RXTE, in the optical and NIR with Gemini North and in the radio with the WSRT. In this paper we present the source-energy distribution. The spectral results obtained in the individual wave bands do not connect smoothly; apparently components of different origin contribute to the total spectrum. Remarkable is that the INTEGRAL hard X-ray spectrum (power-law index 0.79 +/- 0.10) is now measured up to an energy of ~230 keV with no indication of a spectral break. Extrapolation of the INTEGRAL power-law spectrum to lower energies passes orders of magnitude underneath the NIR and optical fluxes, as well as the low ~30 microJy (2 sigma) upper limit in the radio band.

  7. Broad Band X-ray Spectra of Atoll Source 4U 1636-536: NuSTAR and Swift Results

    CERN Document Server

    Agrawal, Vivek Kumar

    2016-01-01

    In this work we investigate broad band (1-79 keV) spectral nature of the atoll source 4U 1636-536 using the combined Nu-STAR and SWIFT-XRT data. The spectra are complex and have emission components from the disc, boundary-layer and corona. In addition to that a broad iron line is also observed. A relativistic line model assuming Schwarzchild metric fits this feature. The total flux varies from 1.4 $\\times$ 10$^{-9}$ to 4.36 $\\times$ 10$^{-9}$ $ergs/s/cm^2$. At the highest flux level the source was found in the soft state. In this state the Comptonized component has temperature $kT_e \\sim 3$ keV and optical depth $\\tau \\sim $ 16. We also detect a non-thermal tail with index $\\sim$ 2.4, contributing $\\sim$ 10 \\% of the total flux in the soft state. We also find that the inner disc radius, electron temperature and optical depth vary with the total 0.1-100 keV unabsorbed flux. We discuss the implication of the results in this paper.

  8. X-ray bursts as a probe of the corona: the case of XRB 4U 1636-536

    CERN Document Server

    Ji, Long; Chen, YuPeng; Zhang, Shuang-Nan; Torres, Diego F; Kretschmar, Peter; Chernyakova, Masha; Li, Jian; Wang, Jian-Min

    2013-01-01

    To investigate the possible cooling of the corona by soft X-rays bursts, we have studied 114 bursts embedded in the known X-ray evolution of 4U 1636-536. We have grouped these bursts according to the ratio of the flux in the 1.5--12 keV band with respect to that in the 15--50 keV band, as monitored by RXTE/ASM and Swift/BAT, respectively. We have detected a shortage at hard X-rays while bursting. This provides hints for a corona cooling process driven by soft X-rays fed by the bursts that occurred on the surface of neutron star. The flux shortage at 30--50 keV has a time lag of 2.4$\\pm$1.5 seconds with respect to that at 2--10 keV, which is comparable to that of 0.7$\\pm$0.5 seconds reported in bursts of IGR 17473-2721. We comment on the possible origin of these phenomena and on the implications for the models on the location of the corona.

  9. VARIATION OF SPECTRAL AND TIMING PROPERTIES IN THE EXTENDED BURST TAILS FROM THE MAGNETAR 4U 0142+61

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Manoneeta; Göğüş, Ersin; Muş, Sinem Şaşmaz; Kaneko, Yuki, E-mail: manoneeta@sabanciuniv.edu [Sabancı University, Faculty of Engineering and Natural Sciences, Orhanlı Tuzla 34956, Istanbul (Turkey)

    2016-03-10

    Extended emission episodes with an intensity above the preburst level are observed following magnetar bursts from a number of soft gamma repeaters and anomalous X-ray pulsars (AXPs). Such extended tail emissions were observed following two events detected from AXP 4U 0142+61. We investigated in detail the evolution of spectral and temporal properties during these two tail segments using Rossi X-ray Timing Explorer/Proportional Counter Array observations, and report distinct variations in the spectral and temporal behavior throughout the tails. In particular, in both cases we observed a sudden enhancement of the pulsation amplitude in conjunction with bursts and a smooth decline of X-ray emission (cooling) during the tail. We suggest that an inefficiently radiating trapped fireball formed during the burst, which can heat up the stellar surface, is able to explain the tail properties and its energetics. We also present the episodic detection of absorption and emission features during tails. One possible mechanism that has been proposed to give rise to such spectral lines is the proton/ion cyclotron resonance process, which has been suggested as offering a valuable tool in probing the complex magnetic field of magnetars.

  10. The featureless and non-variable optical spectral energy distribution of AXP 4U 0142+61

    CERN Document Server

    Muñoz-Darias, T; Casares, J

    2016-01-01

    We present GTC-10.4m spectroscopy and multi-band photometry of the faint (r ~26) optical counterpart of the anomalous X-ray pulsar 4U 0142+61. The 5000 - 9000 Angs spectrum -- the first obtained for a magnetar -- is featureless, allowing us to set an equivalent width upper limit EW < 25 Angs to the presence of emission lines in the Halfa region. Multi-band photometry in the g, r, i, z SDSS bands obtained at different epochs over 12 years shows no significant variability from minutes-to-years time scales. The photometry has been calibrated, for the first time, against the SDSS itself, resulting in solid upper limits to variability ranging from ~0.2 mag in i (over 12 years) to 0.05 mag in z (over 1.5 years). The shape of the optical + near-infrared (literature values) spectral energy distribution is not well constrained due to the high extinction along the line of sight. Using a Markov Chain Monte Carlo analysis we find that it can be described by a power-law with a spectral index beta=-0.7+-0.5 and E_(B-V)=...

  11. The imprint of carbon combustion on a superburst from the accreting neutron star 4U 1636-536

    CERN Document Server

    Keek, L; Wolf, Z; Ballantyne, D R; Suleimanov, V F; Kuulkers, E; Strohmayer, T E

    2015-01-01

    Superbursts are hours-long X-ray flares attributed to the thermonuclear runaway burning of carbon-rich material in the envelope of accreting neutron stars. By studying the details of the X-ray light curve, properties of carbon combustion can be determined. In particular, we show that the shape of the rise of the light curve is set by the the slope of the temperature profile left behind by the carbon flame. We analyse RXTE/PCA observations of 4U 1636-536 and separate the direct neutron star emission from evolving photoionized reflection and persistent spectral components. This procedure results in the highest quality light curve ever produced for the superburst rise and peak, and interesting behaviour is found in the tail. The rising light curve between 100 and 1000 seconds is inconsistent with the idea that the fuel burned locally and instantaneously everywhere, as assumed in some previous models. By fitting improved cooling models, we measure for the first time the radial temperature profile of the superburs...

  12. Characterizing the Evolving X-Ray Spectral Features During a Superburst from 4U 1636-536

    CERN Document Server

    Keek, L; Kuulkers, E; Strohmayer, T E

    2014-01-01

    Recent studies have shown that runaway thermonuclear burning of material accreted onto neutron stars, i.e. Type I X-ray bursts, may affect the accretion disk. We investigate this by performing a detailed time-resolved spectral analysis of the superburst from 4U 1636-536 observed in 2001 with the Rossi X-ray Timing Explorer. Superbursts are attributed to the thermonuclear burning of carbon, and are approximately 1000 times more energetic than the regular short Type I bursts. This allows us to study detailed spectra for over 11 ks, compared to at most 100 s for regular bursts. A feature is present in the superburst spectra around 6.4 keV that is well fit with an emission line and an absorption edge, suggestive of reflection of the superburst off the accretion disk. The line and edge parameters evolve over time: the edge energy decreases from 9.4 keV at the peak to 8.1 keV in the tail, and both features become weaker in the tail. This is only the second superburst for which this has been detected, and shows that...

  13. Constraints on the mass-radius relation of the neutron star in 4U 1746-37/NGC 6441

    Science.gov (United States)

    Sztajno, M.; Fujimoto, M. Y.; Van Paradijs, J.; Vacca, W. D.; Lewin, W. H. G.

    1987-01-01

    An analysis of 12 hours of continuous EXOSAT observations of 4U 1746-37 in NGC 6441, obtained between September 9 and 10, 1985, puts constraints on its mass-radius relation. The spectral shape of the persistent X-ray flux is well fitted by a thermal bremsstrahlung spectrum, with a kT temperature varying between 7.5 and 9.8 keV, and an interstellar column density of about 2.8 x 10 to the 21st/sq cm. Two X-ray bursts noted during the observation are found to be type I, with radius expansion of the neutron star photosphere during their peaks. If the neutron star has a canonical mass of 1.4 solar masses, the observed burst fluxes must be reduced as a result of anisotropy of the burst by a factor of at least 1.3-2.2. The present results are consistent with the very soft and intermediately stiff equations of state.

  14. Variation of Spectral and Timing Properties in the Extended Burst Tails from the Magnetar 4U 0142+61

    CERN Document Server

    Chakraborty, Manoneeta; Muş, Sinem Şaşmaz; Kaneko, Yuki

    2016-01-01

    Extended emission episodes with intensity above the pre-burst level are observed following magnetar bursts from a number of soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). Such extended tail emission were observed subsequent to two events detected from AXP 4U 0142+61. We investigated in detail the evolution of spectral and temporal properties during these two tail segments using RXTE/PCA observations, and report distinct variations both in the spectral and temporal behavior throughout the tails. In particular, sudden enhancement of pulsation amplitude in conjunction with bursts, and smooth decline of X-ray emission (cooling) during the tail were observed in both cases. We suggest that an inefficiently radiating trapped fireball formed during the burst, which can heat up the stellar surface, is able to explain the tail properties and its energetics. We also present the episodic detection of absorption and emission features during tails. One possible mechanism that has been proposed to give rise...

  15. A Link Between X-ray Emission Lines and Radio Jets in 4U 1630-47?

    CERN Document Server

    Neilsen, Joseph; Fender, Rob; Lee, Julia C; Ponti, Gabriele; Tzioumis, Tasso; Edwards, Phil; Broderick, Jess W

    2014-01-01

    Recently, Diaz Trigo et al. reported an XMM-Newton detection of relativistically Doppler-shifted emission lines associated with steep-spectrum radio emission in the stellar-mass black hole candidate 4U 1630-47 during its 2012 outburst. They interpreted these lines as indicative of a baryonic jet launched by the accretion disk. Here we present a search for the same lines earlier in the same outburst using high-resolution X-ray spectra from the Chandra High-Energy Transmission Grating Spectrometer. While our observations (eight months prior to the XMM-Newton campaign) also coincide with detections of steep spectrum radio emission by the Australia Telescope Compact Array, we find no evidence for any relativistic X-ray emission lines. Indeed, despite $\\sim5\\times$ brighter radio emission, our Chandra spectra allow us to place an upper limit on the flux in the blueshifted Fe XXVI line that is $\\gtrsim20\\times$ weaker than the line observed by Diaz Trigo et al. We explore several scenarios that could explain our di...

  16. A LINK BETWEEN X-RAY EMISSION LINES AND RADIO JETS IN 4U 1630-47?

    Energy Technology Data Exchange (ETDEWEB)

    Neilsen, Joseph [Department of Astronomy, Boston University, Boston, MA 02215 (United States); Coriat, Mickaël [Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa); Fender, Rob; Broderick, Jess W. [Department of Physics, Oxford University, Oxford OX1 3RH (United Kingdom); Lee, Julia C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Ponti, Gabriele [Max Planck Institute fur Extraterrestriche Physik, D-85748 Garching (Germany); Tzioumis, Anastasios K.; Edwards, Philip G., E-mail: neilsenj@bu.edu [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia)

    2014-03-20

    Recently, Díaz Trigo et al. reported an XMM-Newton detection of relativistically Doppler-shifted emission lines associated with steep-spectrum radio emission in the stellar-mass black hole candidate 4U 1630-47 during its 2012 outburst. They interpreted these lines as indicative of a baryonic jet launched by the accretion disk. Here we present a search for the same lines earlier in the same outburst using high-resolution X-ray spectra from the Chandra HETGS. While our observations (eight months prior to the XMM-Newton campaign) also coincide with detections of steep spectrum radio emission by the Australia Telescope Compact Array, we find no evidence for any relativistic X-ray emission lines. Indeed, despite ∼5 × brighter radio emission, our Chandra spectra allow us to place an upper limit on the flux in the blueshifted Fe XXVI line that is ≳ 20 × weaker than the line observed by Díaz Trigo et al. We explore several scenarios that could explain our differing results, including variations in the geometry of the jet or a mass-loading process or jet baryon content that evolves with the accretion state of the black hole. We also consider the possibility that the radio emission arises in an interaction between a jet and the nearby interstellar medium, in which case the X-ray emission lines might be unrelated to the radio emission.

  17. Suzaku discovery of iron absorption lines in outburst spectra of the X-ray transient 4U 1630-472

    CERN Document Server

    Kubota, A; Cottam, J; Kotani, T; Done, C; Ueda, Y; Fabian, A C; Yasuda, T; Takahashi, H; Fukazawa, Y; Yamaoka, K; Makishima, K; Yamada, S; Kohmura, T; Angelini, L; Kubota, Aya; Dotani, Tadayasu; Cottam, Jean; Kotani, Taro; Done, Chris; Ueda, Yoshihiro; Fabian, Andrew C.; Yasuda, Tomonori; Takahashi, Hiromitsu; Fukazawa, Yasushi; Yamaoka, Kazutaka; Makishima, Kazuo; Yamada, Shinya; Kohmura, Takayoshi; Angelini, Lorella

    2006-01-01

    We present the results of six Suzaku observations of the recurrent black hole transient 4U1630-472 during its decline from outburst from February 8 to March 23 in 2006. All observations show the typical high/soft state spectral shape in the 2-50keV band, roughly described by an optically thick disk spectrum in the soft energy band plus a weak power-law tail that becomes dominant only above \\~20keV. The disk temperature decreases from 1.4keV to 1.2keV as the flux decreases by a factor 2, consistent with a constant radius as expected for disk-dominated spectra. All the observations reveal significant absorption lines from highly ionized (H-like and He-like) iron Ka at 7.0keV and 6.7keV. The brightest datasets also show significant but weaker absorption structures between 7.8keV and 8.2keV, which we identify as a blend of iron Kb and nickel Ka absorption lines. The energies of these absorption lines suggest a blue shift with an outflow velocity of ~1000km/s.. The H-like iron Ka equivalent width remains approxima...

  18. Orbital Parameters for the Soft X-ray Transient 4U 1543-47 Evidence for a Black Hole

    CERN Document Server

    Orosz, J A; Bailyn, C D; McClintock, J E; Remillard, R A; Orosz, Jerome A.; Jain, Raj K.; Bailyn, Charles D.; Clintock, Jeffrey E. Mc; Remillard, Ronald A.

    1997-01-01

    (shortened) Spectroscopic observations of the soft X-ray transient 4U 1543-47 reveal a radial velocity curve with a period of P=1.123 +/- 0.008 days and a semi-amplitude of K_2 = 124 +/- 4 km/sec. The mass function is f(M) = 0.22 +/- 0.02 solar masses. We derive a distance of d = 9.1 +/-1.1 kpc if the secondary is on the main sequence. The V and I light curves exhibit two waves per orbital cycle with amplitudes of about 0.08 mag. We modeled the light curves as ellipsoidal variations in the secondary star and derive extreme inclination limits of 20 1. However, there are systematic effects in the data that the model does not account for, so the above constraints should be treated with caution. We argue that the secondary star is still on the main sequence and if the secondary star has a mass near the main sequence values for early A-stars (2.3 <= M_2 <= 2.6 solar masses), then the best fits for the 3 sigma inclination range (24 <= i <= 36 deg) and the 3 sigma mass function range (0.16 <= f(M) &l...

  19. Broadband observations of the X-ray burster 4U 1705-44 with BeppoSAX

    CERN Document Server

    Piraino, S; Mueck, B; Kaaret, P; Di Salvo, T; D'Ai, A; Iaria, R; Egron, E

    2016-01-01

    4U 1705-44 is one of the most-studied type I X-ray burster and Atoll sources. This source represents a perfect candidate to test different models proposed to self-consistently track the physical changes occurring between different spectral states because it shows clear spectral state transitions. The broadband coverage, the sensitivity and energy resolution of the BeppoSAX satellite offers the opportunity to disentangle the components that form the total X-ray spectrum and to study their changes according to the spectral state. Using two BeppoSAX observations carried out in August and October 2000, respectively, for a total effective exposure time of about 100 ks, we study the spectral evolution of the source from a soft to hard state. Energy spectra are selected according to the source position in the color-color diagram (CCD) Results. We succeeded in modeling the spectra of the source using a physical self-consistent scenario for both the island and banana branches (the double Comptonization scenario). The ...

  20. Equations of state in the Hartle-Thorne model of neutron stars selecting acceptable variants of the resonant switch model of twin HF QPOs in the atoll source 4U 1636-53

    CERN Document Server

    Stuchlik, Zdenek; Kotrlova, Andrea; Torok, Gabriel; Goluchova, Katerina

    2015-01-01

    The Resonant Switch (RS) model of twin high-frequency quasi-periodic oscillations (HF QPOs) observed in neutron star binary systems, based on switch of the twin oscillations at a resonant point, has been applied to the atoll source 4U 1636-53 under assumption that the neutron star exterior can be approximated by the Kerr geometry. Strong restrictions of the neutron star parameters M (mass) and a (spin) arise due to fitting the frequency pairs admitted by the RS model to the observed data in the regions related to the resonant points. The most precise variants of the RS model are those combining the relativistic precession frequency relations with their modifications. Here, the neutron star mass and spin estimates given by the RS model are confronted with a variety of equations of state (EoS) governing structure of neutron stars in the framework of the Hartle-Thorne theory of rotating neutron stars applied for the observationally given rotation frequency f_rot~580 Hz (or alternatively f_rot~290 Hz) of the neut...

  1. Evolution of Binaries in Dense Stellar Systems

    CERN Document Server

    Ivanova, Natalia

    2011-01-01

    In contrast to the field, the binaries in dense stellar systems are frequently not primordial, and could be either dynamically formed or significantly altered from their primordial states. Destruction and formation of binaries occur in parallel all the time. The destruction, which constantly removes soft binaries from a binary pool, works as an energy sink and could be a reason for cluster entering the binary-burning phase. The true binary fraction is greater than observed, as a result, the observable binary fraction evolves differently from the predictions. Combined measurements of binary fractions in globular clusters suggest that most of the clusters are still core-contracting. The formation, on other hand, affects most the more evolutionary advanced stars, which significantly enhances the population of X-ray sources in globular clusters. The formation of binaries with a compact objects proceeds mainly through physical collisions, binary-binary and single-binary encounters; however, it is the dynamical for...

  2. Spin Correlation in Binary Systems

    CERN Document Server

    Farbiash, N; Farbiash, Netzach; Steinitz, Raphael

    2004-01-01

    We examine the correlation of projected rotational velocities in binary systems. It is an extension of previous work (Steinitz and Pyper, 1970; Levato, 1974). An enlarged data basis and new tests enable us to conclude that there is indeed correlation between the projected rotational velocities of components of binaries. In fact we suggest that spins are already correlated.

  3. Evolutionary Memory in Binary Systems?

    CERN Document Server

    Steinitz, N F R

    2004-01-01

    Correlation between the spins (rotational velocities) in binaries has previously been established. We now continue and show that the degree of spin correlation is independent of the components' separation. Such a result might be related for example to Zhang's non-linear model for the formation of binary stars from a nebula.

  4. Relativistic Binaries in Globular Clusters

    Directory of Open Access Journals (Sweden)

    Matthew J. Benacquista

    2013-03-01

    Full Text Available Galactic globular clusters are old, dense star systems typically containing 10^4 – 10^6 stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution that leads to relativistic binaries, and current and possible future observational evidence for this population. Our discussion of globular cluster evolution will focus on the processes that boost the production of tight binary systems and the subsequent interaction of these binaries that can alter the properties of both bodies and can lead to exotic objects. Direct N-body integrations and Fokker–Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.

  5. PERIODIC COMPLEMENTARY BINARY SEQUENCE PAIRS

    Institute of Scientific and Technical Information of China (English)

    XuChengqian; ZhaoXiaoqun

    2002-01-01

    A new set of binary sequences-Periodic Complementary Binary Sequence Pair (PCSP)is proposed .A new class of block design-Difference Family Pair (DFP)is also proposed .The relationship between PCSP and DFP,the properties and exising conditions of PCSP and the recursive constructions for PCSP are given.

  6. PERIODIC COMPLEMENTARY BINARY SEQUENCE PAIRS

    Institute of Scientific and Technical Information of China (English)

    Xu Chengqian; Zhao Xiaoqun

    2002-01-01

    A new set of binary sequences-Periodic Complementary Binary Sequence Pair (PCSP) is proposed. A new class of block design-Difference Family Pair (DFP) is also proposed.The relationship between PCSP and DFP, the properties and existing conditions of PCSP and the recursive constructions for PCSP are given.

  7. Relativistic Binaries in Globular Clusters

    Directory of Open Access Journals (Sweden)

    Benacquista Matthew J.

    2006-02-01

    Full Text Available The galactic population of globular clusters are old, dense star systems, with a typical cluster containing 10^4 - 10^7 stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss the theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution which lead to relativistic binaries, and current and possible future observational evidence for this population. Globular cluster evolution will focus on the properties that boost the production of hard binary systems and on the tidal interactions of the galaxy with the cluster, which tend to alter the structure of the globular cluster with time. The interaction of the components of hard binary systems alters the evolution of both bodies and can lead to exotic objects. Direct N-body integrations and Fokker-Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.

  8. Relativistic Binaries in Globular Clusters

    Directory of Open Access Journals (Sweden)

    Benacquista Matthew

    2002-01-01

    Full Text Available The galactic population of globular clusters are old, dense star systems, with a typical cluster containing $10^4 - 10^6$ stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss the theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution which lead to relativistic binaries, and current and possible future observational evidence for this population. Globular cluster evolution will focus on the properties that boost the production of hard binary systems and on the tidal interactions of the galaxy with the cluster, which tend to alter the structure of the globular cluster with time. The interaction of the components of hard binary systems alters the evolution of both bodies and can lead to exotic objects. Direct $N$-body integrations and Fokker--Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.

  9. Signature Visualization of Software Binaries

    Energy Technology Data Exchange (ETDEWEB)

    Panas, T

    2008-07-01

    In this paper we present work on the visualization of software binaries. In particular, we utilize ROSE, an open source compiler infrastructure, to pre-process software binaries, and we apply a landscape metaphor to visualize the signature of each binary (malware). We define the signature of a binary as a metric-based layout of the functions contained in the binary. In our initial experiment, we visualize the signatures of a series of computer worms that all originate from the same line. These visualizations are useful for a number of reasons. First, the images reveal how the archetype has evolved over a series of versions of one worm. Second, one can see the distinct changes between version. This allows the viewer to form conclusions about the development cycle of a particular worm.

  10. Observing binary inspiral with LIGO

    CERN Document Server

    Finn, L S

    1994-01-01

    Gravitational radiation from a binary neutron star or black hole system leads to orbital decay and the eventual coalescence of the binary's components. During the last several minutes before the binary components coalesce, the radiation will enter the bandwidth of the United States Laser Inteferometer Gravitational-wave Observatory (LIGO) and the French/Italian VIRGO gravitational radiation detector. The combination of detector sensitivity, signal strength, and source density and distribution all point to binary inspiral as the most likely candidate for observation among all the anticipated sources of gravitational radiation for LIGO/VIRGO. Here I review briefly some of the questions that are posed to theorists by the impending observation of binary inspiral.

  11. Characterizing the evolving X-ray spectral features during a superburst from 4U 1636-536

    Energy Technology Data Exchange (ETDEWEB)

    Keek, L.; Ballantyne, D. R. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430 (United States); Kuulkers, E. [European Space Astronomy Centre (ESA/ESAC), Science Operations Department, E-28691 Villanueva de la Cañada, Madrid (Spain); Strohmayer, T. E., E-mail: l.keek@gatech.edu [X-ray Astrophysics Laboratory, Astrophysics Science Division, NASA' s Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-07-10

    Recent studies have shown that runaway thermonuclear burning of material accreted onto neutron stars, i.e., Type I X-ray bursts, may affect the accretion disk. We investigate this by performing a detailed time-resolved spectral analysis of the superburst from 4U 1636-536 observed in 2001 with the Rossi X-Ray Timing Explorer. Superbursts are attributed to the thermonuclear burning of carbon, and are approximately 1000 times more energetic than the regular short Type I bursts. This allows us to study detailed spectra for over 11 ks, compared to, at most, 100 s for regular bursts. A feature is present in the superburst spectra around 6.4 keV that is well fit with an emission line and an absorption edge, suggestive of reflection of the superburst off the accretion disk. The line and edge parameters evolve over time: the edge energy decreases from 9.4 keV at the peak to 8.1 keV in the tail, and both features become weaker in the tail. This is only the second superburst for which this has been detected and shows that this behavior is present even without strong radius expansion. Furthermore, we find the persistent flux more than doubles during the superburst and returns to the pre-superburst value in the tail. The combination of reflection features and increased persistent emission indicates that the superburst had a strong impact on the inner accretion disk and it emphasizes that X-ray bursts provide a unique probe of accretion physics.

  12. Towards Physarum Binary Adders

    CERN Document Server

    Jones, Jeff; 10.1016/j.biosystems.2010.04.005

    2010-01-01

    Plasmodium of \\emph{Physarum polycephalum} is a single cell visible by unaided eye. The plasmodium's foraging behaviour is interpreted in terms of computation. Input data is a configuration of nutrients, result of computation is a network of plasmodium's cytoplasmic tubes spanning sources of nutrients. Tsuda et al (2004) experimentally demonstrated that basic logical gates can be implemented in foraging behaviour of the plasmodium. We simplify the original designs of the gates and show --- in computer models --- that the plasmodium is capable for computation of two-input two-output gate $ \\to $ and three-input two-output $ \\to $. We assemble the gates in a binary one-bit adder and demonstrate validity of the design using computer simulation.

  13. Towards Physarum binary adders.

    Science.gov (United States)

    Jones, Jeff; Adamatzky, Andrew

    2010-07-01

    Plasmodium of Physarum polycephalum is a single cell visible by unaided eye. The plasmodium's foraging behaviour is interpreted in terms of computation. Input data is a configuration of nutrients, result of computation is a network of plasmodium's cytoplasmic tubes spanning sources of nutrients. Tsuda et al. (2004) experimentally demonstrated that basic logical gates can be implemented in foraging behaviour of the plasmodium. We simplify the original designs of the gates and show - in computer models - that the plasmodium is capable for computation of two-input two-output gate x, y-->xy, x+y and three-input two-output x,y,z-->x yz,x+y+z. We assemble the gates in a binary one-bit adder and demonstrate validity of the design using computer simulation.

  14. Eccentric Binary Millisecond Pulsars

    CERN Document Server

    Freire, Paulo C C

    2009-01-01

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

  15. Dynamical Evolution of Wide Binaries

    Directory of Open Access Journals (Sweden)

    Esmeralda H. Mallada

    2001-01-01

    Full Text Available We simulate numerically encounters of wide binaries with field stars and Giant Molecular Clouds (GMCs by means of the impulse approximation. We analyze the time evolution of the distributions of eccentricities and semimajor axes of wide binaries with given initial conditions, at intervals of 109 yr, up to 1010 yr (assumed age of the Galaxy. We compute the fraction of surviving binaries for stellar encounters, for GMC encounters and for a combination of both, and hence, the dynamical lifetime for different semimajor axes and different masses of binaries (0.5, 1, 1.2, 1.5, 2.5, and 3 Msolar. We find that the dynamical lifetime of wide binaries considering only GMCs is half than that considering only stars. For encounters with GMCs we analyze the influence of the initial inclination of the orbital plane of the binary with respect to the plane perpendicular to the relative velocity vector of the binary and the GMC. We find that the perturbation is maximum when the angle is minimum.

  16. 4U2A型双行马铃薯挖掘机的设计与试验%Design and experimental analysis of 4U2A type double-row potato digger

    Institute of Scientific and Technical Information of China (English)

    吕金庆; 田忠恩; 杨颖; 尚琴琴; 吴金娥

    2015-01-01

    The domestic potato planting shows the main characteristics that it is distributed in scattered plots and hilly mountains regions with less acreage in the south of China. For some large foreign potato harvesters can be used in only few areas. According to the characteristics of domestic potato planting, the most way of harvesting potato is two-stage harvesting, so the digging model of potato harvester is common in the domestic potato diggers and is used in most areas in China. According to the regional users’ feedback information and related field trials, it was found that problems of soil plug and weeds winding often appeared in the process of harvesting, and phenomenon of soil plug was more serious especially in northern cohesive soil. In the north, most of heavy soil not only restricts the development of potato harvest mechanization but also causes the damage of equipment and hence directly affects harvesting efficiency. Soil separation effect of chain elevator parts of potato digger is poor. The technology to prevent weeds winding, soil plug, jams, failure rate and mechanical damage is backward, which causes the damage to machines and tools and affects the efficiency of potato harvest greatly. It can not meet the requirement of the production of heavy soil, and severely restricts the healthy development of potato industry in the regions with heavy soil. So measures should be taken to improve the present situation. There are a lot of potato digger models in domestic, but afore-mentioned problems are almost universal. So designing a machine which can solve the soil plug of potato harvester and weeds winding around on the machine is very necessary. This paper aimed at the problems of chain elevator potato harvester in the process of potato two-stage harvesting, i.e. great resistance, failure rate, high mechanical damage rate and some key technical problems, and the 4U2A type of potato digger was designed. The harvester’s structure and working principle were

  17. Design and experiment on 4U1Z vibrating potato digger%4U1Z型振动式马铃薯挖掘机的设计与试验

    Institute of Scientific and Technical Information of China (English)

    吕金庆; 田忠恩; 吴金娥; 杨颖; 尚琴琴; 王英博; 刘志鑫

    2015-01-01

    Potato has become the important food and cash crop. In recent years, potato planting areas have increased gradually in China, reaching more than 8 million hm2 in 2013. Southwestern mountainous area, Inner Mongolia, northwest of China and northeast of China are the main producing areas of potato. The potato planting area in southwestern mountainous area accounts for about a third of the national total area. Because of the characteristics of the terrain in this area, potato grows mainly in hills and mountains. So only small harvest machines can be used to harvest potatoes. So many potato planting areas result in the higher requirements to the harvest performance of potato harvester. According to the characteristics of potato planting in China, the most ways of harvesting potato are two-stage harvesting, so the digging model of potato harvester is common in the domestic potato harvest process and is used in most areas in China. In order to solve the potato mechanization harvesting problem in plots of hilly mountain or other small plots and small breeding field, in view of the key factors affecting the potato harvest in the areas of hill and mountain, like small plots of land, large slope, rocks, we researched and designed the 4U1Z type of potato digger to solve the related problems. This article described the main structure and working principle of the machine and structure design of key parts. Analysis of kinematics on the digging shovel and vibrating screen mechanism was carried out. The three-dimensional model of the complete machine was established by Solidworks. In Adams/View environment simulation analysis was carried out for the digging shovel and vibrating screen mechanism. We also obtained the relevant images of the kinematics parameters. The theory analysis was combined with simulation analysis method to determine the stability of the machine. Orthogonal test was carried out for the digging shovel and vibrating screen mechanism. The influence factors of

  18. Chaotic zones around gravitating binaries

    CERN Document Server

    Shevchenko, Ivan I

    2014-01-01

    The extent of the continuous zone of chaotic orbits of a small-mass tertiary around a system of two gravitationally bound bodies (a double star, a double black hole, a binary asteroid, etc.) is estimated analytically, in function of the tertiary's orbital eccentricity. The separatrix map theory is used to demonstrate that the central continuous chaos zone emerges due to overlapping of the orbital resonances corresponding to the integer ratios p:1 between the tertiary and the binary periods. The binary's mass ratio, above which such a chaotic zone is universally present, is also estimated.

  19. Modified evolution of stellar binaries from supermassive black hole binaries

    Science.gov (United States)

    Liu, Bin; Wang, Yi-Han; Yuan, Ye-Fei

    2017-04-01

    The evolution of main-sequence binaries resided in the galactic centre is influenced a lot by the central supermassive black hole (SMBH). Due to this perturbation, the stars in a dense environment are likely to experience mergers or collisions through secular or non-secular interactions. In this work, we study the dynamics of the stellar binaries at galactic centre, perturbed by another distant SMBH. Geometrically, such a four-body system is supposed to be decomposed into the inner triple (SMBH-star-star) and the outer triple (SMBH-stellar binary-SMBH). We survey the parameter space and determine the criteria analytically for the stellar mergers and the tidal disruption events (TDEs). For a relative distant and equal masses SMBH binary, the stars have more opportunities to merge as a result from the Lidov-Kozai (LK) oscillations in the inner triple. With a sample of tight stellar binaries, our numerical experiments reveal that a significant fraction of the binaries, ∼70 per cent, experience merger eventually. Whereas the majority of the stellar TDEs are likely to occur at a close periapses to the SMBH, induced by the outer Kozai effect. The tidal disruptions are found numerically as many as ∼10 per cent for a close SMBH binary that is enhanced significantly than the one without the external SMBH. These effects require the outer perturber to have an inclined orbit (≥40°) relatively to the inner orbital plane and may lead to a burst of the extremely astronomical events associated with the detection of the SMBH binary.

  20. Circumstellar discs in X/gamma-ray binaries: first results from the Echelle spectrograph

    CERN Document Server

    Zamanov, R; Martí, J

    2015-01-01

    Here we report our first spectral observations of Be/X-ray and gamma-ray binaries obtained with the new Echelle spectrograph of the National Astronomical Observatory Rozhen. For four objects (LSI+61303, gamma Cas, MWC 148, 4U 2206+54), we report the parameters and estimate the sizes of their circumstellar discs using different emission lines (H-alpha, H-beta, H-gamma, HeI and FeII). For MWC 148, we find that the compact object goes deeply through the disc. The flank inflections of H-alpha can be connected with inner ring formed at the periastron passage or radiation transfer effects. We point out an intriguing similarity between the optical emission lines of the $\\gamma$-ray binary MWC 148 and the well known Be star $\\gamma$ Cas.

  1. Binary Oscillatory Crossflow Electrophoresis

    Science.gov (United States)

    Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

    1997-01-01

    Electrophoresis has long been recognized as an effective analytic technique for the separation of proteins and other charged species, however attempts at scaling up to accommodate commercial volumes have met with limited success. In this report we describe a novel electrophoretic separation technique - Binary Oscillatory Crossflow Electrophoresis (BOCE). Numerical simulations indicate that the technique has the potential for preparative scale throughputs with high resolution, while simultaneously avoiding many problems common to conventional electrophoresis. The technique utilizes the interaction of an oscillatory electric field and a transverse oscillatory shear flow to create an active binary filter for the separation of charged protein species. An oscillatory electric field is applied across the narrow gap of a rectangular channel inducing a periodic motion of charged protein species. The amplitude of this motion depends on the dimensionless electrophoretic mobility, alpha = E(sub o)mu/(omega)d, where E(sub o) is the amplitude of the electric field oscillations, mu is the dimensional mobility, omega is the angular frequency of oscillation and d is the channel gap width. An oscillatory shear flow is induced along the length of the channel resulting in the separation of species with different mobilities. We present a model that predicts the oscillatory behavior of charged species and allows estimation of both the magnitude of the induced convective velocity and the effective diffusivity as a function of a in infinitely long channels. Numerical results indicate that in addition to the mobility dependence, the steady state behavior of solute species may be strongly affected by oscillating fluid into and out of the active electric field region at the ends of the cell. The effect is most pronounced using time dependent shear flows of the same frequency (cos((omega)t)) flow mode) as the electric field oscillations. Under such conditions, experiments indicate that

  2. Stability of binaries. Part II: Rubble-pile binaries

    Science.gov (United States)

    Sharma, Ishan

    2016-10-01

    We consider the stability of the binary asteroids whose members are granular aggregates held together by self-gravity alone. A binary is said to be stable whenever both its members are orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability analysis of Sharma (Sharma [2015] Icarus, 258, 438-453), that is applicable to binaries with rigid members, to the case of binary systems with rubble members. We employ volume averaging (Sharma et al. [2009] Icarus, 200, 304-322), which was inspired by past work on elastic/fluid, rotating and gravitating ellipsoids. This technique has shown promise when applied to rubble-pile ellipsoids, but requires further work to settle some of its underlying assumptions. The stability test is finally applied to some suspected binary systems, viz., 216 Kleopatra, 624 Hektor and 90 Antiope. We also see that equilibrated binaries that are close to mobilizing their maximum friction can sustain only a narrow range of shapes and, generally, congruent shapes are preferred.

  3. Binary nucleation beyond capillarity approximation

    NARCIS (Netherlands)

    Kalikmanov, V.I.

    2010-01-01

    Large discrepancies between binary classical nucleation theory (BCNT) and experiments result from adsorption effects and inability of BCNT, based on the phenomenological capillarity approximation, to treat small clusters. We propose a model aimed at eliminating both of these deficiencies. Adsorption

  4. Discs in misaligned binary systems

    CERN Document Server

    Rawiraswattana, Krisada; Goodwin, Simon P

    2016-01-01

    We perform SPH simulations to study precession and changes in alignment between the circumprimary disc and the binary orbit in misaligned binary systems. We find that the precession process can be described by the rigid-disc approximation, where the disc is considered as a rigid body interacting with the binary companion only gravitationally. Precession also causes change in alignment between the rotational axis of the disc and the spin axis of the primary star. This type of alignment is of great important for explaining the origin of spin-orbit misaligned planetary systems. However, we find that the rigid-disc approximation fails to describe changes in alignment between the disc and the binary orbit. This is because the alignment process is a consequence of interactions that involve the fluidity of the disc, such as the tidal interaction and the encounter interaction. Furthermore, simulation results show that there are not only alignment processes, which bring the components towards alignment, but also anti-...

  5. Simulating relativistic binaries with Whisky

    Science.gov (United States)

    Baiotti, L.

    We report about our first tests and results in simulating the last phase of the coalescence and the merger of binary relativistic stars. The simulations were performed using our code Whisky and mesh refinement through the Carpet driver.

  6. An adaptable binary entropy coder

    Science.gov (United States)

    Kiely, A.; Klimesh, M.

    2001-01-01

    We present a novel entropy coding technique which is based on recursive interleaving of variable-to-variable length binary source codes. We discuss code design and performance estimation methods, as well as practical encoding and decoding algorithms.

  7. Magnetic braking in ultracompact binaries

    CERN Document Server

    Farmer, Alison

    2010-01-01

    Angular momentum loss in ultracompact binaries, such as the AM Canum Venaticorum stars, is usually assumed to be due entirely to gravitational radiation. Motivated by the outflows observed in ultracompact binaries, we investigate whether magnetically coupled winds could in fact lead to substantial additional angular momentum losses. We remark that the scaling relations often invoked for the relative importance of gravitational and magnetic braking do not apply, and instead use simple non-empirical expressions for the braking rates. In order to remove significant angular momentum, the wind must be tied to field lines anchored in one of the binary's component stars; uncertainties remain as to the driving mechanism for such a wind. In the case of white dwarf accretors, we find that magnetic braking can potentially remove angular momentum on comparable or even shorter timescales than gravitational waves over a large range in orbital period. We present such a solution for the 17-minute binary AM CVn itself which a...

  8. Cryptography with DNA binary strands.

    Science.gov (United States)

    Leier, A; Richter, C; Banzhaf, W; Rauhe, H

    2000-06-01

    Biotechnological methods can be used for cryptography. Here two different cryptographic approaches based on DNA binary strands are shown. The first approach shows how DNA binary strands can be used for steganography, a technique of encryption by information hiding, to provide rapid encryption and decryption. It is shown that DNA steganography based on DNA binary strands is secure under the assumption that an interceptor has the same technological capabilities as sender and receiver of encrypted messages. The second approach shown here is based on steganography and a method of graphical subtraction of binary gel-images. It can be used to constitute a molecular checksum and can be combined with the first approach to support encryption. DNA cryptography might become of practical relevance in the context of labelling organic and inorganic materials with DNA 'barcodes'.

  9. Formation of Binary Millisecond Pulsars by Accretion-Induced Collapse of White Dwarfs under Wind-Driven Evolution

    CERN Document Server

    Ablimit, Iminhaji

    2014-01-01

    Accretion-induced collapse of massive white dwarfs (WDs) has been proposed to be an important channel to form binary millisecond pulsars (MSPs). Recent investigations on thermal timescale mass transfer in WD binaries demonstrate that the resultant MSPs are likely to have relatively wide orbit periods ($\\gtrsim 10$ days). Here we calculate the evolution of WD binaries taking into account the excited wind from the companion star induced by X-ray irradiation of the accreting WD, which may drive rapid mass transfer even when the companion star is less massive than the WD. This scenario can naturally explain the formation of the strong-field neutron star in the low-mass X-ray binary 4U 1822$-$37. After AIC the mass transfer resumes when the companion star refills its Roche lobe, and the neutron star is recycled due to mass accretion. A large fraction of the binaries will evolve to become binary MSPs with a He WD companion, with the orbital periods distributed between $\\gtrsim 0.1$ day and $\\lesssim 30$ days, while...

  10. AN IMPROVED DESIGN OF REVERSIBLE BINARY TO BINARY CODED DECIMAL CONVERTER FOR BINARY CODED DECIMAL MULTIPLICATION

    Directory of Open Access Journals (Sweden)

    Praveena Murugesan

    2014-01-01

    Full Text Available Reversible logic gates under ideal conditions produce zero power dissipation. This factor highlights the usage of these gates in optical computing, low power CMOS design, quantum optics and quantum computing. The growth of decimal arithmetic in various applications as stressed the need to propose the study on reversible binary to BCD converter which plays a greater role in decimal multiplication for providing faster results. The different parameters such as gate count,garbage output and constant input are more optimized in the proposed fixed bit binary to binary coded decimal converter than the existing design.

  11. Transient Black Hole Binaries

    CERN Document Server

    Belloni, T M

    2016-01-01

    The last two decades have seen a great improvement in our understand- ing of the complex phenomenology observed in transient black-hole binary systems, especially thanks to the activity of the Rossi X-Ray Timing Explorer satellite, com- plemented by observations from many other X-ray observatories and ground-based radio, optical and infrared facilities. Accretion alone cannot describe accurately the intricate behavior associated with black-hole transients and it is now clear that the role played by different kinds of (often massive) outflows seen at different phases of the outburst evolution of these systems is as fundamental as the one played by the accretion process itself. The spectral-timing states originally identified in the X-rays and fundamentally based on the observed effect of accretion, have acquired new importance as they now allow to describe within a coherent picture the phenomenology observed at other wave- length, where the effects of ejection processes are most evident. With a particular focu...

  12. Residue arithmetic in binary systems

    OpenAIRE

    Barsi, Ferruccio

    1988-01-01

    A natural approach to the problem of performing mod m computations in a binary system is presented and a solution is suggested which is based upon a straightforward relation between the residues of a same integer X with respect to different moduli. The proposed solution proves fruitful in various applications, such as converting binary integers to residue notation and mod m addition or multiplication. Even if the most usual implementation approach for mod m processors is based on look-up tabl...

  13. Coevolution of Binaries and Gaseous Discs

    CERN Document Server

    Fleming, David P

    2016-01-01

    The recent discoveries of circumbinary planets by $\\it Kepler$ raise questions for contemporary planet formation models. Understanding how these planets form requires characterizing their formation environment, the circumbinary protoplanetary disc, and how the disc and binary interact and change as a result. The central binary excites resonances in the surrounding protoplanetary disc that drive evolution in both the binary orbital elements and in the disc. To probe how these interactions impact binary eccentricity and disc structure evolution, N-body smooth particle hydrodynamics (SPH) simulations of gaseous protoplanetary discs surrounding binaries based on Kepler 38 were run for $10^4$ binary periods for several initial binary eccentricities. We find that nearly circular binaries weakly couple to the disc via a parametric instability and excite disc eccentricity growth. Eccentric binaries strongly couple to the disc causing eccentricity growth for both the disc and binary. Discs around sufficiently eccentri...

  14. Unsupervised learning of binary vectors

    Science.gov (United States)

    Copelli Lopes da Silva, Mauro

    In this thesis, unsupervised learning of binary vectors from data is studied using methods from Statistical Mechanics of disordered systems. In the model, data vectors are distributed according to a single symmetry-breaking direction. The aim of unsupervised learning is to provide a good approximation to this direction. The difference with respect to previous studies is the knowledge that this preferential direction has binary components. It is shown that sampling from the posterior distribution (Gibbs learning) leads, for general smooth distributions, to an exponentially fast approach to perfect learning in the asymptotic limit of large number of examples. If the distribution is non-smooth, then first order phase transitions to perfect learning are expected. In the limit of poor performance, a second order phase transition ("retarded learning") is predicted to occur if the data distribution is not biased. Using concepts from Bayesian inference, the center of mass of the Gibbs ensemble is shown to have maximal average (Bayes-optimal) performance. This upper bound for continuous vectors is extended to a discrete space, resulting in the clipped center of mass of the Gibbs ensemble having maximal average performance among the binary vectors. To calculate the performance of this best binary vector, the geometric properties of the center of mass of binary vectors are studied. The surprising result is found that the center of mass of infinite binary vectors which obey some simple constraints, is again a binary vector. When disorder is taken into account in the calculation, however, a vector with continuous components is obtained. The performance of the best binary vector is calculated and shown to always lie above that of Gibbs learning and below the Bayes-optimal performance. Making use of a variational approach under the replica symmetric ansatz, an optimal potential is constructed in the limits of zero temperature and mutual overlap 1. Minimization of this potential

  15. Automated cell tracking and analysis in phase-contrast videos (iTrack4U): development of Java software based on combined mean-shift processes.

    Science.gov (United States)

    Cordelières, Fabrice P; Petit, Valérie; Kumasaka, Mayuko; Debeir, Olivier; Letort, Véronique; Gallagher, Stuart J; Larue, Lionel

    2013-01-01

    Cell migration is a key biological process with a role in both physiological and pathological conditions. Locomotion of cells during embryonic development is essential for their correct positioning in the organism; immune cells have to migrate and circulate in response to injury. Failure of cells to migrate or an inappropriate acquisition of migratory capacities can result in severe defects such as altered pigmentation, skull and limb abnormalities during development, and defective wound repair, immunosuppression or tumor dissemination. The ability to accurately analyze and quantify cell migration is important for our understanding of development, homeostasis and disease. In vitro cell tracking experiments, using primary or established cell cultures, are often used to study migration as cells can quickly and easily be genetically or chemically manipulated. Images of the cells are acquired at regular time intervals over several hours using microscopes equipped with CCD camera. The locations (x,y,t) of each cell on the recorded sequence of frames then need to be tracked. Manual computer-assisted tracking is the traditional method for analyzing the migratory behavior of cells. However, this processing is extremely tedious and time-consuming. Most existing tracking algorithms require experience in programming languages that are unfamiliar to most biologists. We therefore developed an automated cell tracking program, written in Java, which uses a mean-shift algorithm and ImageJ as a library. iTrack4U is a user-friendly software. Compared to manual tracking, it saves considerable amount of time to generate and analyze the variables characterizing cell migration, since they are automatically computed with iTrack4U. Another major interest of iTrack4U is the standardization and the lack of inter-experimenter differences. Finally, iTrack4U is adapted for phase contrast and fluorescent cells.

  16. Automated cell tracking and analysis in phase-contrast videos (iTrack4U: development of Java software based on combined mean-shift processes.

    Directory of Open Access Journals (Sweden)

    Fabrice P Cordelières

    Full Text Available Cell migration is a key biological process with a role in both physiological and pathological conditions. Locomotion of cells during embryonic development is essential for their correct positioning in the organism; immune cells have to migrate and circulate in response to injury. Failure of cells to migrate or an inappropriate acquisition of migratory capacities can result in severe defects such as altered pigmentation, skull and limb abnormalities during development, and defective wound repair, immunosuppression or tumor dissemination. The ability to accurately analyze and quantify cell migration is important for our understanding of development, homeostasis and disease. In vitro cell tracking experiments, using primary or established cell cultures, are often used to study migration as cells can quickly and easily be genetically or chemically manipulated. Images of the cells are acquired at regular time intervals over several hours using microscopes equipped with CCD camera. The locations (x,y,t of each cell on the recorded sequence of frames then need to be tracked. Manual computer-assisted tracking is the traditional method for analyzing the migratory behavior of cells. However, this processing is extremely tedious and time-consuming. Most existing tracking algorithms require experience in programming languages that are unfamiliar to most biologists. We therefore developed an automated cell tracking program, written in Java, which uses a mean-shift algorithm and ImageJ as a library. iTrack4U is a user-friendly software. Compared to manual tracking, it saves considerable amount of time to generate and analyze the variables characterizing cell migration, since they are automatically computed with iTrack4U. Another major interest of iTrack4U is the standardization and the lack of inter-experimenter differences. Finally, iTrack4U is adapted for phase contrast and fluorescent cells.

  17. Exoplanets Bouncing Between Binary Stars

    CERN Document Server

    Moeckel, Nickolas

    2012-01-01

    Exoplanetary systems are found not only among single stars, but also binaries of widely varying parameters. Binaries with separations of 100--1000 au are prevalent in the Solar neighborhood; at these separations planet formation around a binary member may largely proceed as if around a single star. During the early dynamical evolution of a planetary system, planet--planet scattering can eject planets from a star's grasp. In a binary, the motion of a planet ejected from one star has effectively entered a restricted three-body system consisting of itself and the two stars, and the equations of motion of the three body problem will apply as long as the ejected planet remains far from the remaining planets. Depending on its energy, escape from the binary as a whole may be impossible or delayed until the three-body approximation breaks down, and further close interactions with its planetary siblings boost its energy when it passes close to its parent star. Until then this planet may be able to transition from the ...

  18. Formation of Kuiper Belt Binaries

    CERN Document Server

    Goldreich, P; Sari, R; Goldreich, Peter; Lithwick, Yoram; Sari, Re'em

    2002-01-01

    It appears that at least several percent of large Kuiper belt objects are members of wide binaries. Physical collisions are too infrequent to account for their formation. Collisionless gravitational interactions are more promising. These provide two channels for binary formation. In each, the initial step is the formation of a transient binary when two large bodies penetrate each other's Hill spheres. Stabilization of a transient binary requires that it lose energy. Either dynamical friction due to small bodies or the scattering of a third large body can be responsible. Our estimates favor the former, albeit by a small margin. We predict that most objects of size comparable to those currently observed in the Kuiper belt are members of multiple systems. More specifically, we derive the probability that a large body is a member of a binary with semi-major axis of order a. The probability depends upon sigma, the total surface density, Sigma, the surface density of large bodies having radius R, and theta=10^-4, t...

  19. The Bardeen-Petterson Effect as a Possible Mechanism for Quasi-periodic Oscillations in X-Ray Binaries

    CERN Document Server

    Fragile, P C; Wilson, J R; Mathews, Grant J.; Wilson, James R.

    2001-01-01

    The Bardeen-Petterson effect around a rapidly rotating compact object causes a tilted accretion disk to warp into the equatorial plane of the rotating body at a characteristic radius. We show that the orbital frequency at this transition radius naturally falls into a range (2-1600 Hz) required to explain observed quasi-periodic oscillations (QPOs) in low-mass X-ray binaries (LMXBs). The Bardeen-Petterson effect also complements some interpretations of observed QPO frequency correlations. We show that it may also provide an explanation for the non-monotonic behavior of count rate vs. QPO frequency plots for the LMXBs 4U 1820-30 and 4U 1735-44.

  20. Evaporative Instability in Binary Mixtures

    Science.gov (United States)

    Narayanan, Ranga; Uguz, Erdem

    2012-11-01

    In this talk we depict the physics of evaporative convection for binary systems in the presence of surface tension gradient effects. Two results are of importance. The first is that a binary system, in the absence of gravity, can generate an instability only when heated from the vapor side. This is to be contrasted with the case of a single component where instability can occur only when heated from the liquid side. The second result is that a binary system, in the presence of gravity, will generate an instability when heated from either the vapor or the liquid side provided the heating is strong enough. In addition to these results we show the conditions at which interfacial patterns can occur. Support from NSF OISE 0968313, Partner Univ. Fund and a Chateaubriand Fellowship is acknowledged.

  1. Marangoni Convection in Binary Mixtures

    CERN Document Server

    Zhang, J; Oron, A; Behringer, Robert P.; Oron, Alexander; Zhang, Jie

    2006-01-01

    Marangoni instabilities in binary mixtures are different from those in pure liquids. In contrast to a large amount of experimental work on Marangoni convection in pure liquids, such experiments in binary mixtures are not available in the literature, to our knowledge. Using binary mixtures of sodium chloride/water, we have systematically investigated the pattern formation for a set of substrate temperatures and solute concentrations in an open system. The flow patterns evolve with time, driven by surface-tension fluctuations due to evaporation and the Soret effect, while the air-liquid interface does not deform. A shadowgraph method is used to follow the pattern formation in time. The patterns are mainly composed of polygons and rolls. The mean pattern size first decreases slightly, and then gradually increases during the evolution. Evaporation affects the pattern formation mainly at the early stage and the local evaporation rate tends to become spatially uniform at the film surface. The Soret effect becomes i...

  2. Asymmetric distances for binary embeddings.

    Science.gov (United States)

    Gordo, Albert; Perronnin, Florent; Gong, Yunchao; Lazebnik, Svetlana

    2014-01-01

    In large-scale query-by-example retrieval, embedding image signatures in a binary space offers two benefits: data compression and search efficiency. While most embedding algorithms binarize both query and database signatures, it has been noted that this is not strictly a requirement. Indeed, asymmetric schemes that binarize the database signatures but not the query still enjoy the same two benefits but may provide superior accuracy. In this work, we propose two general asymmetric distances that are applicable to a wide variety of embedding techniques including locality sensitive hashing (LSH), locality sensitive binary codes (LSBC), spectral hashing (SH), PCA embedding (PCAE), PCAE with random rotations (PCAE-RR), and PCAE with iterative quantization (PCAE-ITQ). We experiment on four public benchmarks containing up to 1M images and show that the proposed asymmetric distances consistently lead to large improvements over the symmetric Hamming distance for all binary embedding techniques.

  3. Black Hole Binaries in Quiescence

    CERN Document Server

    Bailyn, Charles D

    2016-01-01

    I discuss some of what is known and unknown about the behavior of black hole binary systems in the quiescent accretion state. Quiescence is important for several reasons: 1) the dominance of the companion star in the optical and IR wavelengths allows the binary parameters to be robustly determined - as an example, we argue that the longer proposed distance to the X-ray source GRO J1655-40 is correct; 2) quiescence represents the limiting case of an extremely low accretion rate, in which both accretion and jets can be observed; 3) understanding the evolution and duration of the quiescent state is a key factor in determining the overall demographics of X-rary binaries, which has taken on a new importance in the era of gravitational wave astronomy.

  4. Practical Binary Adaptive Block Coder

    CERN Document Server

    Reznik, Yuriy A

    2007-01-01

    This paper describes design of a low-complexity algorithm for adaptive encoding/ decoding of binary sequences produced by memoryless sources. The algorithm implements universal block codes constructed for a set of contexts identified by the numbers of non-zero bits in previous bits in a sequence. We derive a precise formula for asymptotic redundancy of such codes, which refines previous well-known estimate by Krichevsky and Trofimov, and provide experimental verification of this result. In our experimental study we also compare our implementation with existing binary adaptive encoders, such as JBIG's Q-coder, and MPEG AVC (ITU-T H.264)'s CABAC algorithms.

  5. Statistical Study of Visual Binaries

    CERN Document Server

    Abdel-Rahman, H I; Elsanhoury, W H

    2016-01-01

    In this paper, some statistical distributions of wide pairs included in Double Star Catalogue are investigated. Frequency distributions and testing hypothesis are derived for some basic parameters of visual binaries. The results reached indicate that, it was found that the magnitude difference is distributed exponentially, which means that the majority of the component of the selected systems is of the same spectral type. The distribution of the mass ratios is concentrated about 0.7 which agree with Salpeter mass function. The distribution of the linear separation appears to be exponentially, which contradict with previous studies for close binaries.

  6. KEPLER ECLIPSING BINARIES WITH STELLAR COMPANIONS

    Energy Technology Data Exchange (ETDEWEB)

    Gies, D. R.; Matson, R. A.; Guo, Z.; Lester, K. V. [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 5060, Atlanta, GA 30302-5060 (United States); Orosz, J. A. [Department of Astronomy, San Diego State University, San Diego, CA 92182-1221 (United States); Peters, G. J., E-mail: gies@chara.gsu.edu, E-mail: rmatson@chara.gsu.edu, E-mail: guo@chara.gsu.edu, E-mail: lester@chara.gsu.edu, E-mail: jorosz@mail.sdsu.edu, E-mail: gjpeters@mucen.usc.edu [Space Sciences Center and Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-1341 (United States)

    2015-12-15

    Many short-period binary stars have distant orbiting companions that have played a role in driving the binary components into close separation. Indirect detection of a tertiary star is possible by measuring apparent changes in eclipse times of eclipsing binaries as the binary orbits the common center of mass. Here we present an analysis of the eclipse timings of 41 eclipsing binaries observed throughout the NASA Kepler mission of long duration and precise photometry. This subset of binaries is characterized by relatively deep and frequent eclipses of both stellar components. We present preliminary orbital elements for seven probable triple stars among this sample, and we discuss apparent period changes in seven additional eclipsing binaries that may be related to motion about a tertiary in a long period orbit. The results will be used in ongoing investigations of the spectra and light curves of these binaries for further evidence of the presence of third stars.

  7. Binary/BCD-to-ASCII data converter

    Science.gov (United States)

    Miller, A. J.

    1977-01-01

    Converter inputs multiple precision binary words, converts data to multiple precision binary-coded decimal, and routes data back to computer. Converter base can be readily changed without need for new gate structure for each base changeover.

  8. Binary stars in the RAVE survey

    Directory of Open Access Journals (Sweden)

    Zwitter T.

    2012-02-01

    Full Text Available We searched the sample of RAVE survey spectra for both types of spectroscopic binary stars in order to estimate their number in the sample and perform a study on newly discovered binaries.

  9. Bayesian analysis of binary sequences

    Science.gov (United States)

    Torney, David C.

    2005-03-01

    This manuscript details Bayesian methodology for "learning by example", with binary n-sequences encoding the objects under consideration. Priors prove influential; conformable priors are described. Laplace approximation of Bayes integrals yields posterior likelihoods for all n-sequences. This involves the optimization of a definite function over a convex domain--efficiently effectuated by the sequential application of the quadratic program.

  10. CHAOTIC ZONES AROUND GRAVITATING BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Shevchenko, Ivan I., E-mail: iis@gao.spb.ru [Pulkovo Observatory of the Russian Academy of Sciences, Pulkovskoje ave. 65, St. Petersburg 196140 (Russian Federation)

    2015-01-20

    The extent of the continuous zone of chaotic orbits of a small-mass tertiary around a system of two gravitationally bound primaries of comparable masses (a binary star, a binary black hole, a binary asteroid, etc.) is estimated analytically, as a function of the tertiary's orbital eccentricity. The separatrix map theory is used to demonstrate that the central continuous chaos zone emerges (above a threshold in the primaries' mass ratio) due to overlapping of the orbital resonances corresponding to the integer ratios p:1 between the tertiary and the central binary periods. In this zone, the unlimited chaotic orbital diffusion of the tertiary takes place, up to its ejection from the system. The primaries' mass ratio, above which such a chaotic zone is universally present at all initial eccentricities of the tertiary, is estimated. The diversity of the observed orbital configurations of biplanetary and circumbinary exosystems is shown to be in accord with the existence of the primaries' mass parameter threshold.

  11. A Galactic Binary Detection Pipeline

    Science.gov (United States)

    Littenberg, Tyson B.

    2011-01-01

    The Galaxy is suspected to contain hundreds of millions of binary white dwarf systems, a large fraction of which will have sufficiently small orbital period to emit gravitational radiation in band for space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA). LISA's main science goal is the detection of cosmological events (supermassive black hole mergers, etc.) however the gravitational signal from the galaxy will be the dominant contribution to the data - including instrumental noise over approximately two decades in frequency. The catalogue of detectable binary systems will serve as an unparalleled means of studying the Galaxy. Furthermore, to maximize the scientific return from the mission, the data must be "cleansed" of the galactic foreground. We will present an algorithm that can accurately resolve and subtract 2:: 10000 of these sources from simulated data supplied by the Mock LISA Data Challenge Task Force. Using the time evolution of the gravitational wave frequency, we will reconstruct the position of the recovered binaries and show how LISA will sample the entire compact binary population in the Galaxy.

  12. The Meritfactor of Binary Seqences

    DEFF Research Database (Denmark)

    Høholdt, Tom

    1999-01-01

    Binary sequences with small aperiodic correlations play an important role in many applications ranging from radar to modulation and testing of systems. Golay(1977) introduced the merit factor as a measure of the goodness of the sequence and conjectured an upper bound for this. His conjecture is s...

  13. Eccentricity distribution of wide binaries

    CERN Document Server

    Tokovinin, Andrei

    2015-01-01

    A sample of 477 solar-type binaries within 67pc with projected separations larger than 50AU is studied by a new statistical method. Speed and direction of the relative motion are determined from the short observed arcs or known orbits, and their joint distribution is compared to the numerical simulations. By inverting the observed distribution with the help of simulations, we find that average eccentricity of wide binaries is 0.59+-0.02 and the eccentricity distribution can be modeled as f(e) ~= 1.2 e + 0.4. However, wide binaries containing inner subsystems, i.e. triple or higher-order multiples, have significantly smaller eccentricities with the average e = 0.52+-0.05 and the peak at e ~ 0.5. We find that the catalog of visual orbits is strongly biased against large eccentricities. A marginal evidence of eccentricity increasing with separation (or period) is found for this sample. Comparison with spectroscopic binaries proves the reality of the controversial period-eccentricity relation. The average eccentr...

  14. Coevolution of binaries and circumbinary gaseous discs

    Science.gov (United States)

    Fleming, David P.; Quinn, Thomas R.

    2017-01-01

    The recent discoveries of circumbinary planets by Kepler raise questions for contemporary planet formation models. Understanding how these planets form requires characterizing their formation environment, the circumbinary protoplanetary disc and how the disc and binary interact and change as a result. The central binary excites resonances in the surrounding protoplanetary disc which drive evolution in both the binary orbital elements and in the disc. To probe how these interactions impact binary eccentricity and disc structure evolution, N-body smooth particle hydrodynamics simulations of gaseous protoplanetary discs surrounding binaries based on Kepler 38 were run for 104 binary periods for several initial binary eccentricities. We find that nearly circular binaries weakly couple to the disc via a parametric instability and excite disc eccentricity growth. Eccentric binaries strongly couple to the disc causing eccentricity growth for both the disc and binary. Discs around sufficiently eccentric binaries which strongly couple to the disc develop an m = 1 spiral wave launched from the 1:3 eccentric outer Lindblad resonance which corresponds to an alignment of gas particle longitude of periastrons. All systems display binary semimajor axis decay due to dissipation from the viscous disc.

  15. Formation and evolution of compact binaries

    NARCIS (Netherlands)

    Sluijs, Marcel Vincent van der

    2006-01-01

    In this thesis we investigate the formation and evolution of compact binaries. Chapters 2 through 4 deal with the formation of luminous, ultra-compact X-ray binaries in globular clusters. We show that the proposed scenario of magnetic capture produces too few ultra-compact X-ray binaries to explain

  16. Gravitational Microlensing of Binary and Binary and Multiple Stars

    Science.gov (United States)

    Cherepashchuk, A. M.

    1995-08-01

    Recent observations of the effect of microlensing of stars of large Magellanic Clouds by dark bodies of Galactic Halo have led to the discovery of new population in our galaxy - dark bodies with amsses ~ 0.1 M(sun). As a consequence, astronomers have gained a unique possibility of using gravitational microlensing as an effective extraterestrial telescope with extremely high angular resolution. Application of this to binary stars is discussed. of particular interest is to apply microlensing to search for planetary stars . Planets and stars move about the center of gravity of the system , so the appaarent motion of a star in nonuniform and the light curve is asymetrical and colour dependent. This allows to determin basic parameters of binary system

  17. Permutation Entropy for Random Binary Sequences

    Directory of Open Access Journals (Sweden)

    Lingfeng Liu

    2015-12-01

    Full Text Available In this paper, we generalize the permutation entropy (PE measure to binary sequences, which is based on Shannon’s entropy, and theoretically analyze this measure for random binary sequences. We deduce the theoretical value of PE for random binary sequences, which can be used to measure the randomness of binary sequences. We also reveal the relationship between this PE measure with other randomness measures, such as Shannon’s entropy and Lempel–Ziv complexity. The results show that PE is consistent with these two measures. Furthermore, we use PE as one of the randomness measures to evaluate the randomness of chaotic binary sequences.

  18. Populating the Galaxy with close Be binaries

    CERN Document Server

    Kiel, P D; Murray, J R; Hayasaki, K

    2007-01-01

    Be/X-ray binaries comprise roughly two-thirds of the high-mass X-ray binaries (HMXBs), which is a class of X-ray binaries that results from the high mass of the companion or donor star (> 10 solar masses). Currently the formation and evolution of X-ray producing Be binaries is a matter of great debate. Modelling of these systems requires knowledge of Be star evolution and also consideration of how the evolution changes when the star is in close proximity to a companion. Within this work we complete a full population synthesis study of Be binaries for the Galaxy. The results for the first time match aspects of the observational data, most notably the observed upper limit to the period distribution. We conclude that greater detailed studies on the evolution of Be stars within X-ray binaries needs to be completed, so that rapid binary evolution population synthesis packages may best evolve these systems.

  19. Adsorption of Th4+, U6+, Cd2+, and Ni2+ from aqueous solution by a novel modified polyacrylonitrile composite nanofiber adsorbent prepared by electrospinning

    Science.gov (United States)

    Dastbaz, Abolfazl.; Keshtkar, Ali Reza.

    2014-02-01

    In this study, SiO2 nanoparticles were modified by 3-aminopropyltriethoxysilane (APTES) and then applied to prepare a novel polyacrylonitrile (PAN) composite nanofiber adsorbent by the electrospinning method. In addition, the adsorbent was characterized by SEM, BET, and FTIR analyses. Then the effects of pH, SiO2 and APTES content, adsorbent dosage, contact time and temperature were investigated. Moreover, adsorption experiments were carried out with initial concentrations in the range of 30-500 mg L-1 and the adsorbent affinity for metal ions was in order of Th4+ > U6+ > Cd2+ > Ni2+. Furthermore, it was observed that the optimum pH for adsorption was different for each metal. Some isotherm and kinetic models were applied to analyze the experimental data, among which the Langmuir and pseudo-second order models were better than the others. The regeneration study showed that the adsorbent could be used for industrial processes repeatedly without any significant reduction in its adsorption capacity. Based on the Langmuir model, the maximum adsorption capacity of Th4+, U6+, Cd2+, and Ni2+ at 45 °C was 249.4, 193.1, 69.5 and 138.7 mg g-1, respectively. Besides, the calculated thermodynamic parameters showed an endothermic as well as chemical nature through the adsorption process.

  20. Evidence of a decrease of kHz QPO peak separation towards low frequencies in 4U 1728-34 (GX 354-0)

    CERN Document Server

    Migliari, S; Fender, R; Migliari, Simone; Klis, Michiel van der; Fender, Rob

    2003-01-01

    We have produced the colour-colour diagram of all the observations of 4U 1728-34 available in the Rossi X-ray Timing Explorer public archive (from 1996 to 2002) and found observations filling in a previously reported 'gap' between the island and the banana X-ray states. We have made timing analysis of these gap observations and found, in one observation, two simultaneous kHz quasi-periodic oscillations (QPOs). The timing parameters of these kHz QPOs fit in the overall trend of the source. The 'lower' kHz QPO has a centroid frequency of ~308 Hz. This is the lowest 'lower' kHz QPO frequency ever observed in 4U 1728-34. The peak frequency separation between the 'upper' and the 'lower' kHz QPO is 274+/-11 Hz, significantly smaller than the constant value of ~350 Hz found when the 'lower' kHz QPO frequency is between ~500 and 800 Hz. This is the first indication in this source for a significant decrease of kHz QPO peak separation towards low frequencies. We briefly compare the result to theoretical models for kHz ...

  1. INTEGRAL Galactic Plane Scans detect enhanced activity from the HMXBs IGR J19294+1816 and 4U 1909+07

    DEFF Research Database (Denmark)

    Drave, S. P.; Sguera, V.; Fiocchi, M.;

    2013-01-01

    exposures of ~7.9 and ~2.9 ks respectively but neither were detected, with 6sigma flux upper limits of 6 mCrab and 8 mCrab in the 3-10 keV band respectively. 4U 1909+07 is a wind-fed SgXRB pulsar whose past variability is consistent with the enhanced flux detected in these observations. IGR J19294...... at a significant level during observations in the previous revolution (1293) performed between 2013-05-18 UTC 03:55:28 and 15:59:42. IGR J19294+1816 was detected at an IBIS/ISGRI count rate of 3.1±0.4 counts s-1 in the 18-60 keV band, corresponding to a significance of 7.2 sigma and a flux of ~17 m......Crab, for an exposure of 19.7 ks. 4U 1909+07 was detected at a count rate of 3.7±0.5 counts s-1 in the same band, corresponding to a significance of 7.0 sigma and a flux of ~ 20 mCrab (with an exposure of 13.5 ks). Both sources were also in the field of view of the soft X-ray JEM-X instrument for total effective...

  2. Close supermassive binary black holes

    Science.gov (United States)

    Gaskell, C. Martin

    2010-01-01

    It has been proposed that when the peaks of the broad emission lines in active galactic nuclei (AGNs) are significantly blueshifted or redshifted from the systemic velocity of the host galaxy, this could be a consequence of orbital motion of a supermassive blackhole binary (SMB). The AGN J1536+0441 (=SDSS J153636.22+044127.0) has recently been proposed as an example of this phenomenon. It is proposed here instead that 1536+044 is an example of line emission from a disc. If this is correct, the lack of clear optical spectral evidence for close SMBs is significant and argues either that the merging of close SMBs is much faster than has generally been hitherto thought, or if the approach is slow, that when the separation of the binary is comparable to the size of the torus and broad-line region, the feeding of the black holes is disrupted.

  3. Desktop setup for binary holograms

    Science.gov (United States)

    Ginter, Olaf; Rothe, Hendrik

    1996-08-01

    Binary gratings as holograms itself or as photographic masking tools for further fabrication steps can fulfill a lot of applications. The commonly used semiconductor technologies for direct writing of high resolution structures are often too expensive. On the other hand computer plots at a reasonable price with photographic reduction do not meet the needs of precision e.g. for interferometric inspection. The lack of cheap and reliable instruments for direct writing in an appropriate resolution is still a problem in fabricating synthetic holograms. Using off-the-shelf components a direct writing plotter for binary patterns can be built at moderate costs. Typical design rules as well as experimental results are given and the final setup is introduced.

  4. Slim Sets of Binary Trees

    CERN Document Server

    Grünewald, Stefan

    2010-01-01

    A classical problem in phylogenetic tree analysis is to decide whether there is a phylogenetic tree $T$ that contains all information of a given collection $\\cP$ of phylogenetic trees. If the answer is "yes" we say that $\\cP$ is compatible and $T$ displays $\\cP$. This decision problem is NP-complete even if all input trees are quartets, that is binary trees with exactly four leaves. In this paper, we prove a sufficient condition for a set of binary phylogenetic trees to be compatible. That result is used to give a short and self-contained proof of the known characterization of quartet sets of minimal cardinality which are displayed by a unique phylogenetic tree.

  5. Mass transfer between binary stars

    Science.gov (United States)

    Modisette, J. L.; Kondo, Y.

    1980-01-01

    The transfer of mass from one component of a binary system to another by mass ejection is analyzed through a stellar wind mechanism, using a model which integrates the equations of motion, including the energy equation, with an initial static atmosphere and various temperature fluctuations imposed at the base of the star's corona. The model is applied to several situations and the energy flow is calculated along the line of centers between the two binary components, in the rotating frame of the system, thereby incorporating the centrifugal force. It is shown that relatively small disturbances in the lower chromosphere or photosphere can produce mass loss through a stellar wind mechanism, due to the amplification of the disturbance propagating into the thinner atmosphere. Since there are many possible sources of the disturbance, the model can be used to explain many mass ejection phenomena.

  6. RXTE/ASM and Swift / BAT observations of spectral transitions in bright X-ray binaries in 2005-2010

    Institute of Scientific and Technical Information of China (English)

    Jing Tang; Wen-Fei Yu; Zhen Yan

    2011-01-01

    We have studied X-ray spectral state transitions that can be seen in the longterm monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert Telescope (BAT) onboard Swift during a period of five years from 2005 to 2010. We have applied a program to automatically identify the hard-to-soft (H-S) spectral state transitions in the bright X-ray binaries monitored by the ASM and the BAT. In total, we identified 128 hard-to-soft transitions, of which 59 occurred after 2008. We also determined the transition fluxes and the peak fluxes of the following soft states, updated the measurements of the luminosity corresponding to the H-S transition and the peak luminosity of the following soft state in about 30 bright persistent and transient black hole and neutron star binaries following Yu &Yan, and found the luminosity correlation and the luminosity range of spectral transitions in data between 2008-2010 are about the same as those derived from data before 2008. This further strengthens the idea that the luminosity at which the H-S spectral transition occurs in the Galactic X-ray binaries is determined by non-stationary accretion parameters such as the rate-of-change of the mass accretion rate rather than the mass accretion rate itself. The correlation is also found to hold in data of individual sources 4U 1608-52 and 4U 1636-53.

  7. Classification with binary gene expressions

    OpenAIRE

    Tuna, Salih; Niranjan, Mahesan

    2009-01-01

    Microarray gene expression measurements are reported, used and archived usually to high numerical precision. However, properties of mRNA molecules, such as their low stability and availability in small copy numbers, and the fact that measurements correspond to a population of cells, rather than a single cell, makes high precision meaningless. Recent work shows that reducing measurement precision leads to very little loss of information, right down to binary levels. In this paper we show how p...

  8. Binary neuron with optical devices

    Science.gov (United States)

    Degeratu, Vasile; Degeratu, Ştefania; Şchiopu, Paul; Şchiopu, Carmen

    2009-01-01

    In this paper the authors present a model of binary neuron, a model of McCulloch-Pitts neuron with optical devices. This model of neuron can be implemented not only in the optic integrated circuits but also in the classic optical circuits it being cheap and immune not only into electromagnetic fields but also into any kind of radiation. The transfer speed of information through the neuron is very higher, it being limited only by the light speed from the received medium.

  9. Be/X-ray binaries

    CERN Document Server

    Reig, Pablo

    2011-01-01

    The purpose of this work is to review the observational properties of Be/X-ray binaries. The open questions in Be/X-ray binaries include those related to the Be star companion, that is, the so-called "Be phenomenon", such as, timescales associated to the formation and dissipation of the equatorial disc, mass-ejection mechanisms, V/R variability, and rotation rates; those related to the neutron star, such as, mass determination, accretion physics, and spin period evolution; but also, those that result from the interaction of the two constituents, such as, disc truncation and mass transfer. Until recently, it was thought that the Be stars' disc was not significantly affected by the neutron star. In this review, I present the observational evidence accumulated in recent years on the interaction between the circumstellar disc and the compact companion. The most obvious effect is the tidal truncation of the disc. As a result, the equatorial discs in Be/X-ray binaries are smaller and denser than those around isolat...

  10. Visual Binaries in the Orion Nebula Cluster

    CERN Document Server

    Reipurth, Bo; Connelley, Michael S; Bally, John

    2007-01-01

    We have carried out a major survey for visual binaries towards the Orion Nebula Cluster using HST images obtained with an H-alpha filter. Among 781 likely ONC members more than 60" from theta-1 Ori C, we find 78 multiple systems (75 binaries and 3 triples), of which 55 are new discoveries, in the range from 0.1" to 1.5". About 9 binaries are likely line-of-sight associations. We find a binary fraction of 8.8%+-1.1% within the limited separation range from 67.5 to 675 AU. The field binary fraction in the same range is a factor 1.5 higher. Within the range 150 AU to 675 AU we find that T Tauri associations have a factor 2.2 more binaries than the ONC. The binary separation distribution function of the ONC shows unusual structure, with a sudden steep decrease in the number of binaries as the separation increases beyond 0.5", corresponding to 225 AU. We have measured the ratio of binaries wider than 0.5" to binaries closer than 0.5" as a function of distance from the Trapezium, and find that this ratio is signifi...

  11. Mutation in the splicing factor Hprp3p linked to retinitis pigmentosa impairs interactions within the U4/U6 snRNP complex.

    Science.gov (United States)

    Gonzalez-Santos, Juana Maria; Cao, Huibi; Duan, Rongqi Cathleen; Hu, Jim

    2008-01-15

    Mutations in PRPF3, a gene encoding the essential pre-mRNA splicing factor Hprp3p, have been identified in patients with autosomal dominant retinitis pigmentosa type 18 (RP18). Patients with RP18 have one of two single amino acid substitutions, Pro493Ser or Thr494Met, at the highly conserved Hprp3p C-terminal region. Pro493Ser occurs sporadically, whereas Thr494Met is observed in several unlinked RP families worldwide. The latter mutation also alters a potential recognition motif for phosphorylation by casein kinase II (CKII). To understand the molecular basis of RP18, we examined the consequences of Thr494Met mutation on Hprp3p molecular interactions with components of the U4/U6.U5 small nuclear ribonucleoprotein particles (snRNPs) complex. Since numerous mutations causing human diseases change pre-mRNA splice sites, we investigated whether Thr494Met substitution affects the processing of PRPF3 mRNA. We found that Thr494Met does not affect PRPF3 mRNA processing, indicating that the mutation may exert its effect primarily at the protein level. We used small hairpin RNAs to specifically silence the endogenous PRPF3 while simultaneously expressing HA-tagged Thr494Met. We demonstrated that the C- but not N-terminal region of Hprp3p is indeed phosphorylated by CKII in vitro and in cells. CKII-mediated Hprp3p phosphorylation was significantly reduced by Thr494Met mutation. Consequently, the Hprp3p C-terminal region is rendered partially defective in its association with itself, Hprp4p, and U4/U6 snRNA. Our findings provide new insights into the biology of Hprp3p and suggest that the loss of Hprp3p phosphorylation at Thr494 is a key step for initiating Thr494Met aberrant interactions within U4/U6 snRNP complex and that these are likely linked to the RP18 phenotype.

  12. u471cb.m77t - MGD77 data file for Geophysical data from field activity UGEOLEG_4 (U-4-71-CB) in Venezuela, Caribbean Sea from 08/18/1971 to 10/01/1971

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Single-beam bathymetry,gravity, and magnetic data along with transit satellite navigation data was collected as part of field activity UGEOLEG_4 (U-4-71-CB) in...

  13. Uhuru observations of 4U 1608-52 - The 'steady' X-ray source associated with the X-ray burst source in Norma

    Science.gov (United States)

    Tananbaum, H.; Chaisson, L. J.; Forman, W.; Jones, C.; Matilsky, T. A.

    1976-01-01

    Data are presented for the X-ray source 4U 1608-52, summarizing its light curve, location, and spectral parameters. Evidence is presented showing that this source is the 'steady' X-ray counterpart of the X-ray burst source in Norma. The spectrum of the 'steady' source is compared with the spectrum observed during two bursts, and it is noted that there is substantially more low-energy absorption during the bursts. The 'steady' source spectral data are used to examine the optical data, and it is concluded that if the X-ray spectrum is thermal, then a globular-cluster counterpart probably would have been detected (whereas none has been). Further X-ray and optical observations are suggested for this source, since an optical identification may be central in determining whether all X-ray bursts have a common origin and if this origin requires a globular-cluster environment.

  14. A 4 U laser heterodyne radiometer for methane (CH4) and carbon dioxide (CO2) measurements from an occultation-viewing CubeSat

    Science.gov (United States)

    Wilson, Emily L.; DiGregorio, A. J.; Riot, Vincent J.; Ammons, Mark S.; Bruner, William W.; Carter, Darrell; Mao, Jianping; Ramanathan, Anand; Strahan, Susan E.; Oman, Luke D.; Hoffman, Christine; Garner, Richard M.

    2017-03-01

    We present a design for a 4 U (20 cm  ×  20 cm  ×  10 cm) occultation-viewing laser heterodyne radiometer (LHR) that measures methane (CH4), carbon dioxide (CO2) and water vapor (H2O) in the limb that is designed for deployment on a 6 U CubeSat. The LHR design collects sunlight that has undergone absorption by the trace gas and mixes it with a distributive feedback (DFB) laser centered at 1640 nm that scans across CO2, CH4, and H2O absorption features. Upper troposphere/lower stratosphere measurements of these gases provide key inputs to stratospheric circulation models: measuring stratospheric circulation and its variability is essential for projecting how climate change will affect stratospheric ozone.

  15. Microlensing Signature of Binary Black Holes

    Science.gov (United States)

    Schnittman, Jeremy; Sahu, Kailash; Littenberg, Tyson

    2012-01-01

    We calculate the light curves of galactic bulge stars magnified via microlensing by stellar-mass binary black holes along the line-of-sight. We show the sensitivity to measuring various lens parameters for a range of survey cadences and photometric precision. Using public data from the OGLE collaboration, we identify two candidates for massive binary systems, and discuss implications for theories of star formation and binary evolution.

  16. Detection of unresolved binaries with multicolor photometry

    CERN Document Server

    Chulkov, D; Malkov, O; Sichevskij, S; Krussanova, N; Mironov, A; Zakharov, A; Kniazev, A

    2016-01-01

    The principal goal of this paper is to specify conditions of detection of unresolved binaries by multicolor photometry. We have developed a method for estimating the critical distance at which an unresolved binary of given mass and age can be detected. The method is applied to the photometric system of the planned Lyra-B spaceborne experiment. We have shown that some types of unresolved binary stars can be discovered and distinguished from single stars solely by means of photometric observations.

  17. Speech perception of noise with binary gains

    DEFF Research Database (Denmark)

    Wang, DeLiang; Kjems, Ulrik; Pedersen, Michael Syskind;

    2008-01-01

    For a given mixture of speech and noise, an ideal binary time-frequency mask is constructed by comparing speech energy and noise energy within local time-frequency units. It is observed that listeners achieve nearly perfect speech recognition from gated noise with binary gains prescribed...... by the ideal binary mask. Only 16 filter channels and a frame rate of 100 Hz are sufficient for high intelligibility. The results show that, despite a dramatic reduction of speech information, a pattern of binary gains provides an adequate basis for speech perception....

  18. Survival of planets around shrinking stellar binaries.

    Science.gov (United States)

    Muñoz, Diego J; Lai, Dong

    2015-07-28

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov-Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like.

  19. The structures of binary compounds

    CERN Document Server

    Hafner, J; Jensen, WB; Majewski, JA; Mathis, K; Villars, P; Vogl, P; de Boer, FR

    1990-01-01

    - Up-to-date compilation of the experimental data on the structures of binary compounds by Villars and colleagues. - Coloured structure maps which order the compounds into their respective structural domains and present for the first time the local co-ordination polyhedra for the 150 most frequently occurring structure types, pedagogically very helpful and useful in the search for new materials with a required crystal structure. - Crystal co-ordination formulas: a flexible notation for the interpretation of solid-state structures by chemist Bill Jensen. - Recent important advances in unders

  20. X-ray reflection in oxygen-rich accretion discs of ultracompact X-ray binaries

    DEFF Research Database (Denmark)

    Madej, O. K.; Garcia, Jeronimo; Jonker, P. G.

    2014-01-01

    We present spectroscopic X-ray data of two candidate ultracompact X-ray binaries (UCXBs): 4U 0614+091 and 4U 1543-624. We confirm the presence of a broad O viii Ly alpha reflection line (at a parts per thousand 18 angstrom) using XMM-Newton and Chandra observations obtained in 2012 and 2013....... The donor star in these sources is a carbon-oxygen or oxygen-neon-magnesium white dwarf. Hence, the accretion disc is enriched with oxygen which makes the O viii Ly alpha line particularly strong. Modelling the X-ray reflection off a carbon- and oxygen-enriched, hydrogen- and helium-poor disc with models...... assuming solar composition likely biases several of the best-fitting parameters. In order to describe the X-ray reflection spectra self-consistently, we modify the currently available xillver reflection model. We present initial grids that can be used to model X-ray reflection spectra in UCXBs with carbon...

  1. R144 : a very massive binary likely ejected from R136 through a binary-binary encounter

    CERN Document Server

    Oh, Seungkyung; Banerjee, Sambaran

    2013-01-01

    R144 is a recently confirmed very massive, spectroscopic binary which appears isolated from the core of the massive young star cluster R136. The dynamical ejection hypothesis as an origin for its location is claimed improbable by Sana et al. due to its binary nature and high mass. We demonstrate here by means of direct N-body calculations that a very massive binary system can be readily dynamically ejected from a R136-like cluster, through a close encounter with a very massive system. One out of four N-body cluster models produces a dynamically ejected very massive binary system with a mass comparable to R144. The system has a system mass of $\\approx$ 355 Msun and is located at 36.8 pc from the centre of its parent cluster, moving away from the cluster with a velocity of 57 km/s at 2 Myr as a result of a binary-binary interaction. This implies that R144 could have been ejected from R136 through a strong encounter with an other massive binary or single star. In addition, we discuss all massive binaries and sin...

  2. Interacting Jets from Binary Protostars

    CERN Document Server

    Murphy, G C; O'Sullivan, S; Spicer, D; Bacciotti, F; Rosén, A

    2007-01-01

    We investigate potential models that could explain why multiple proto-stellar systems predominantly show single jets. During their formation, stars most frequently produce energetic outflows and jets. However, binary jets have only been observed in a very small number of systems. We model numerically 3D binary jets for various outflow parameters. We also model the propagation of jets from a specific source, namely L1551 IRS 5, known to have two jets, using recent observations as constraints for simulations with a new MHD code. We examine their morphology and dynamics, and produce synthetic emission maps. We find that the two jets interfere up to the stage where one of them is almost destroyed or engulfed into the second one. We are able to reproduce some of the observational features of L1551 such as the bending of the secondary jet. While the effects of orbital motion are negligible over the jets dynamical timeline, their interaction has significant impact on their morphology. If the jets are not strictly pa...

  3. The Young Visual Binary Database

    Science.gov (United States)

    Prato, Lisa A.; Avilez, Ian; Allen, Thomas; Zoonematkermani, Saeid; Biddle, Lauren; Muzzio, Ryan; Wittal, Matthew; Schaefer, Gail; Simon, Michal

    2017-01-01

    We have obtained adaptive optics imaging and high-resolution H-band and in some cases K-band spectra of each component in close to 100 young multiple systems in the nearby star forming regions of Taurus, Ophiuchus, TW Hya, and Orion. The binary separations for the pairs in our sample range from 30 mas to 3 arcseconds. The imaging and most of our spectra were obtained with instruments behind adaptive optics systems in order to resolve even the closest companions. We are in the process of determining fundamental stellar and circumstellar properties, such as effective temperature, Vsin(i), veiling, and radial velocity, for each component in the entire sample. The beta version of our database includes systems in the Taurus region and provides plots, downloadable ascii spectra, and values of the stellar and circumstellar properties for both stars in each system. This resource is openly available to the community at http://jumar.lowell.edu/BinaryStars/. In this poster we describe initial results from our analysis of the survey data. Support for this research was provided in part by NSF award AST-1313399 and by NASA Keck KPDA funding.

  4. Millisecond Pulsars in Close Binaries

    CERN Document Server

    Tauris, Thomas M

    2015-01-01

    In this Habilitationsschrift (Habilitation thesis) I present my research carried out over the last four years at the Argelander Institute for Astronomy (AIfA) and the Max Planck Institute for Radio Astronomy (MPIfR). The thesis summarizes my main findings and has been written to fulfill the requirements for the Habilitation qualification at the University of Bonn. Although my work is mainly focused on the topic of millisecond pulsars (MSPs), there is a fairly broad spread of research areas ranging from the formation of neutron stars (NSs) in various supernova (SN) events, to their evolution, for example, via accretion processes in binary and triple systems, and finally to their possible destruction in merger events. The thesis is organized in the following manner: A general introduction to neutron stars and millisecond pulsars is given in Chapter 1. A selection of key papers published in 2011-2014 are presented in Chapters 2-10, ordered within five main research areas (ultra-stripped SNe in close binaries, ma...

  5. Binary Relations as a Foundation of Mathematics

    NARCIS (Netherlands)

    Kuper, J.; Barendsen, E.; Capretta, V.; Geuvers, H.; Niqui, M.

    2007-01-01

    We describe a theory for binary relations in the Zermelo-Fraenkel style. We choose for ZFCU, a variant of ZFC Set theory in which the Axiom of Foundation is replaced by an axiom allowing for non-wellfounded sets. The theory of binary relations is shown to be equi-consistent ZFCU by constructing a mo

  6. Binary Structure in David Lodge's Novels

    Institute of Scientific and Technical Information of China (English)

    高萍

    2008-01-01

    David Lodge is one of the most renowned modern English writers.He is known for the binary structure in his novels.In this paper,the writer will try to the binary structure in some of his novels to show his reflections on Catholicism and culture conflicts.

  7. Microlensing Binaries with Candidate Brown Dwarf Companions

    DEFF Research Database (Denmark)

    Shin, I.-G; Han, C.; Gould, A.;

    2012-01-01

    Brown dwarfs are important objects because they may provide a missing link between stars and planets, two populations that have dramatically different formation histories. In this paper, we present the candidate binaries with brown dwarf companions that are found by analyzing binary microlensing ...

  8. Helium in atmospheres of binary stars

    Energy Technology Data Exchange (ETDEWEB)

    Leushin, V.V. (Rostovskij-na-Donu Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Fiziki)

    The helium abundances were obtained for 25 bright components of binary stars by model atmosphere analysis. The helium abundance for binary stars that lie on the main sequence are larger in the average than in single normal stars. The stars on the Hertzsppung - russel diagram lie at a larger distance from the zero age line than those with normal helium abundance.

  9. The Evolution of Compact Binary Star Systems

    Directory of Open Access Journals (Sweden)

    Yungelson, Lev R.

    2006-12-01

    Full Text Available We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs, neutron stars (NSs, and black holes (BHs. Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA. Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.

  10. The Evolution of Compact Binary Star Systems

    Directory of Open Access Journals (Sweden)

    Konstantin A. Postnov

    2014-05-01

    Full Text Available We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs, neutron stars (NSs, and black holes (BHs. Mergings of compact-star binaries are expected to be the most important sources for forthcoming gravitational-wave (GW astronomy. In the first part of the review, we discuss observational manifestations of close binaries with NS and/or BH components and their merger rate, crucial points in the formation and evolution of compact stars in binary systems, including the treatment of the natal kicks, which NSs and BHs acquire during the core collapse of massive stars and the common envelope phase of binary evolution, which are most relevant to the merging rates of NS-NS, NS-BH and BH-BH binaries. The second part of the review is devoted mainly to the formation and evolution of binary WDs and their observational manifestations, including their role as progenitors of cosmologically-important thermonuclear SN Ia. We also consider AM CVn-stars, which are thought to be the best verification binary GW sources for future low-frequency GW space interferometers.

  11. Bayesian analysis of exoplanet and binary orbits

    OpenAIRE

    Schulze-Hartung, Tim; Launhardt, Ralf; Henning, Thomas

    2012-01-01

    We introduce BASE (Bayesian astrometric and spectroscopic exoplanet detection and characterisation tool), a novel program for the combined or separate Bayesian analysis of astrometric and radial-velocity measurements of potential exoplanet hosts and binary stars. The capabilities of BASE are demonstrated using all publicly available data of the binary Mizar A.

  12. Binary Representations of Fingerprint Spectral Minutiae Features

    NARCIS (Netherlands)

    Xu, Haiyun; Veldhuis, Raymond N.J.

    2010-01-01

    A fixed-length binary representation of a fingerprint has the advantages of a fast operation and a small template storage. For many biometric template protection schemes, a binary string is also required as input. The spectral minutiae representation is a method to represent a minutiae set as a fixe

  13. The Evolution of Compact Binary Star Systems.

    Science.gov (United States)

    Postnov, Konstantin A; Yungelson, Lev R

    2014-01-01

    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Mergings of compact-star binaries are expected to be the most important sources for forthcoming gravitational-wave (GW) astronomy. In the first part of the review, we discuss observational manifestations of close binaries with NS and/or BH components and their merger rate, crucial points in the formation and evolution of compact stars in binary systems, including the treatment of the natal kicks, which NSs and BHs acquire during the core collapse of massive stars and the common envelope phase of binary evolution, which are most relevant to the merging rates of NS-NS, NS-BH and BH-BH binaries. The second part of the review is devoted mainly to the formation and evolution of binary WDs and their observational manifestations, including their role as progenitors of cosmologically-important thermonuclear SN Ia. We also consider AM CVn-stars, which are thought to be the best verification binary GW sources for future low-frequency GW space interferometers.

  14. Binary Planetary Nebulae Nuclei towards the Galactic Bulge. I. Sample Discovery, Period Distribution and Binary Fraction

    CERN Document Server

    Miszalski, B; Moffat, A F J; Parker, Q A; Udalski, A

    2009-01-01

    Binarity has been hypothesised to play an important, if not ubiquitous, role in the formation of planetary nebulae (PNe). Yet there remains a severe paucity of known binary central stars required to test the binary hypothesis and to place strong constraints on the physics of the common-envelope (CE) phase of binary stellar evolution. Large photometric surveys offer an unrivalled opportunity to efficiently discover many binary central stars. We have combined photometry from the OGLE microlensing survey with the largest sample of PNe towards the Galactic Bulge to systematically search for new binaries. A total of 21 periodic binaries were found thereby more than doubling the known sample. The orbital period distribution was found to be best described by CE population synthesis models when no correlation between primary and secondary masses is assumed for the initial mass ratio distribution. A comparison with post-CE white dwarf binaries indicates both distributions are representative of the true post-CE period ...

  15. Planet Scattering Around Binaries: Ejections, Not Collisions

    CERN Document Server

    Smullen, Rachel A; Shannon, Andrew

    2016-01-01

    Transiting circumbinary planets discovered by Kepler provide unique insight into binary and planet formation. Several features of this new found population, for example the apparent pile-up of planets near the innermost stable orbit, may distinguish between formation theories. In this work, we determine how planet-planet scattering shapes planetary systems around binaries as compared to single stars. In particular, we look for signatures that arise due to differences in dynamical evolution in binary systems. We carry out a parameter study of N-body scattering simulations for four distinct planet populations around both binary and single stars. While binarity has little influence on the final system multiplicity or orbital distribution, the presence of a binary dramatically effects the means by which planets are lost from the system. Most circumbinary planets are lost due to ejections rather than planet-planet or planet-star collisions. The most massive planet in the system tends to control the evolution. Asid...

  16. Evolution of non-synchronized binary systems

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A model for binary evolution is introduced which can determine whether the rotation of components is synchronized with the orbital motion, and can calculate the evolution of both the synchronized and non-synchronized binary systems. With this model, the evolution of a binary system consisting of a 9 M⊙ star and a 6 M⊙ star is studied with mass transfer Case B. The result shows that the synchronization of the rotational and orbital periods can be reached when the binary system is a detached system and before the occurrence of the first mass transfer. After the onset of the first mass transfer, the binary system becomes non-synchronized. The mass accepted component (the secondary) rotates faster with a period much smaller than that of the orbital motion.

  17. Evolution of non-synchronized binary systems

    Institute of Scientific and Technical Information of China (English)

    黄润乾; 曾艺蓉

    2000-01-01

    A model for binary evolution is introduced which can determine whether the rotation of components is synchronized with the orbital motion, and can calculate the evolution of both the synchronized and non-synchronized binary systems. With this model, the evolution of a binary system consisting of a 9 M star and a 6 M star is studied with mass transfer Case B. The result shows that the synchronization of the rotational and orbital periods can be reached when the binary system is a detached system and before the occurrence of the first mass transfer. After the onset of the first mass transfer, the binary system becomes non-synchronized. The mass accepted component (the secondary) rotates faster with a period much smaller than that of the orbital motion.

  18. Terrestrial Planet Formation in Binary Star Systems

    Science.gov (United States)

    Lissauer, J. J.; Quintana, E. V.; Adams, F. C.; Chambers, J. E.

    2006-01-01

    Most stars reside in binary/multiple star systems; however, previous models of planet formation have studied growth of bodies orbiting an isolated single star. Disk material has been observed around one or both components of various young close binary star systems. If planets form at the right places within such disks, they can remain dynamically stable for very long times. We have simulated the late stages of growth of terrestrial planets in both circumbinary disks around 'close' binary star systems with stellar separations ($a_B$) in the range 0.05 AU $\\le a_B \\le$ 0.4 AU and binary eccentricities in the range $0 \\le e \\le 0.8$ and circumstellar disks around individual stars with binary separations of tens of AU. The initial disk of planetary embryos is the same as that used for simulating the late stages of terrestrial planet growth within our Solar System and around individual stars in the Alpha Centauri system (Quintana et al. 2002, A.J., 576, 982); giant planets analogous to Jupiter and Saturn are included if their orbits are stable. The planetary systems formed around close binaries with stellar apastron distances less than or equal to 0.2 AU with small stellar eccentricities are very similar to those formed in the Sun-Jupiter-Saturn, whereas planetary systems formed around binaries with larger maximum separations tend to be sparser, with fewer planets, especially interior to 1 AU. Likewise, when the binary periastron exceeds 10 AU, terrestrial planets can form over essentially the entire range of orbits allowed for single stars with Jupiter-like planets, although fewer terrestrial planets tend to form within high eccentricity binary systems. As the binary periastron decreases, the radial extent of the terrestrial planet systems is reduced accordingly. When the periastron is 5 AU, the formation of Earth-like planets near 1 AU is compromised.

  19. Binary mixtures of chiral gases

    CERN Document Server

    Presilla, Carlo

    2015-01-01

    A possible solution of the well known paradox of chiral molecules is based on the idea of spontaneous symmetry breaking. At low pressure the molecules are delocalized between the two minima of a given molecular potential while at higher pressure they become localized in one minimum due to the intermolecular dipole-dipole interactions. Evidence for such a phase transition is provided by measurements of the inversion spectrum of ammonia and deuterated ammonia at different pressures. In particular, at pressure greater than a critical value no inversion line is observed. These data are well accounted for by a model previously developed and recently extended to mixtures. In the present paper, we discuss the variation of the critical pressure in binary mixtures as a function of the fractions of the constituents.

  20. Binary Cepheids from optical interferometry

    CERN Document Server

    Gallenne, A; Mérand, A; Monnier, J D; Pietrzyński, J Breitfelder G; Gieren, W

    2013-01-01

    Classical Cepheid stars have been considered since more than a century as reliable tools to estimate distances in the universe thanks to their Period-Luminosity (P-L) relationship. Moreover, they are also powerful astrophysical laboratories, providing fundamental clues for studying the pulsation and evolution of intermediate-mass stars. When in binary systems, we can investigate the age and evolution of the Cepheid, estimate the mass and distance, and constrain theoretical models. However, most of the companions are located too close to the Cepheid (1-40 mas) to be spatially resolved with a 10-meter class telescope. The only way to spatially resolve such systems is to use long-baseline interferometry. Recently, we have started a unique and long-term interferometric program that aims at detecting and characterizing physical parameters of the Cepheid companions, with as main objectives the determination of accurate masses and geometric distances.

  1. Record-Breaking Eclipsing Binary

    Science.gov (United States)

    Kohler, Susanna

    2016-05-01

    A new record holder exists for the longest-period eclipsing binary star system: TYC-2505-672-1. This intriguing system contains a primary star that is eclipsed by its companion once every 69 years with each eclipse lasting several years!120 Years of ObservationsIn a recent study, a team of scientists led by Joseph Rodriguez (Vanderbilt University) characterizes the components of TYC-2505-672-1. This binary star system consists of an M-type red giant star that undergoes a ~3.45-year-long, near-total eclipse with a period of ~69.1 years. This period is more than double that of the previous longest-period eclipsing binary!Rodriguez and collaborators combined photometric observations of TYC-2505-672-1 by the Kilodegree Extremely Little Telescope (KELT) with a variety of archival data, including observations by the American Association of Variable Star Observers (AAVSO) network and historical data from the Digital Access to a Sky Century @ Harvard (DASCH) program.In the 120 years spanned by these observations, two eclipses are detected: one in 1942-1945 and one in 2011-2015. The authors use the observations to analyze the components of the system and attempt to better understand what causes its unusual light curve.Characterizing an Unusual SystemObservations of TYC-2505-672-1 plotted from 1890 to 2015 reveal two eclipses. (The blue KELT observations during the eclipse show upper limits only.) [Rodriguez et al. 2016]By modeling the systems emission, Rodriguez and collaborators establish that TYC-2505-672-1 consists of a 3600-K primary star thats the M giant orbited by a small, hot, dim companion thats a toasty 8000 K. But if the companion is small, why does the eclipse last several years?The authors argue that the best model of TYC-2505-672-1 is one in which the small companion star is surrounded by a large, opaque circumstellar disk. Rodriguez and collaborators suggest that the companion could be a former red giant whose atmosphere was stripped from it, leaving behind

  2. Stability of multiplanet systems in binaries

    Science.gov (United States)

    Marzari, F.; Gallina, G.

    2016-10-01

    Context. When exploring the stability of multiplanet systems in binaries, two parameters are normally exploited: the critical semimajor axis ac computed by Holman & Wiegert (1999, AJ, 117, 621) within which planets are stable against the binary perturbations, and the Hill stability limit Δ determining the minimum separation beyond which two planets will avoid mutual close encounters. Both these parameters are derived in different contexts, i.e. Δ is usually adopted for computing the stability limit of two planets around a single star while ac is computed for a single planet in a binary system. Aims: Our aim is to test whether these two parameters can be safely applied in multiplanet systems in binaries or if their predictions fail for particular binary orbital configurations. Methods: We have used the frequency map analysis (FMA) to measure the diffusion of orbits in the phase space as an indicator of chaotic behaviour. Results: First we revisited the reliability of the empirical formula computing ac in the case of single planets in binaries and we find that, in some cases, it underestimates by 10-20% the real outer limit of stability and it does not account for planets trapped in resonance with the companion star well beyond ac. For two-planet systems, the value of Δ is close to that computed for planets around single stars, but the level of chaoticity close to it substantially increases for smaller semimajor axes and higher eccentricities of the binary orbit. In these configurations ac also begins to be unreliable and non-linear secular resonances with the stellar companion lead to chaotic behaviour well within ac, even for single planet systems. For two planet systems, the superposition of mean motion resonances, either mutual or with the binary companion, and non-linear secular resonances may lead to chaotic behaviour in all cases. We have developed a parametric semi-empirical formula determining the minimum value of the binary semimajor axis, for a given

  3. INTEGRAL and BeppoSAX observations of the transient atoll source 4U 1608-522: from quiescent to hard spectral state

    CERN Document Server

    Tarana, Antonella; Ubertini, Pietro

    2008-01-01

    In this paper we report on the spectral evolution of 4U 1608-522 performed as part of the long Galactic Bulge monitoring with INTEGRAL. The data set include the April 2005 outburst. BeppoSAX archival data (two observations, in 1998 and 2000) have been also analysed and compared with the INTEGRAL ones. Three different spectral states have been identified from the hard Color-Intensity diagram derived from INTEGRAL: the canonical Hard and Soft as well as an Intermediate state. The hard state spectrum is well described by a weak black body component plus a Comptonised plasma component with high electron temperature (kTe~60 keV) extending up to 200 keV without any additional cut-off. The soft spectra are characterized by a cold Comptonised plasma (kTe= 2-3 keV, and 7 keV for the intermediate state) and a strong disk black body component. A reflection component, indicating reflection of the X-ray radiation from the accretion disc, is also present in the soft state revealed by BeppoSAX in 1998. The 2000 BeppoSAX obs...

  4. Disk Dominated States of 4U 1957+11: Chandra, XMM, and RXTE Observations of Ostensibly the Most Rapidly Spinning Galactic Black Hole

    CERN Document Server

    Nowak, Michael A; Homan, Jeroen; Yao, Yangsen; Wilms, Joern; Schulz, Norbert S; Canizares, Claude R

    2008-01-01

    We present simultaneous Chandra-HETG and RXTE observations of a moderate flux `soft state' of the black hole candidate 4U1957+11. These spectra, having a minimally discernible hard X-ray excess, are an excellent test of modern disk atmosphere models that include the effects of black hole spin. The HETG data show that the soft disk spectrum is only very mildly absorbed with N_H =1-2 X 10^{21} cm^-2. These data additionally reveal 13.449 A NeIX absorption consistent with the warm/hot phase of the interstellar medium. The fitted disk model implies a highly inclined disk around a low mass black hole rapidly rotating with normalized spin a*~1. We show, however, that pure Schwarzschild black hole models describe the data extremely well, albeit with large disk atmosphere ``color-correction'' factors. Standard color-correction factors can be attained if one additionally incorporates mild Comptonization. We find that the Chandra observations do not uniquely determine spin. Similarly, XMM/RXTE observations, taken only ...

  5. Detailed high-energy characteristics of AXP 4U 0142+61 - Multi-year observations with INTEGRAL, RXTE, XMM-Newton and ASCA

    CERN Document Server

    Hartog, P R den; Hermsen, W; Kaspi, V M; Dib, R; Knödlseder, J; Gavriil, F P

    2008-01-01

    We present detailed spectral and temporal characteristics both in the hard X-ray (>10 keV) and soft X-ray (<10 keV) domains, obtained using data from INTEGRAL, XMM-Newton, ASCA and RXTE. The INTEGRAL time-averaged total spectrum shows a power-law like shape with photon index Gamma = 0.93 +/- 0.06. 4U 0142+61 is detected up to 229 keV and the flux between 20 keV and 229 keV is (15.01 +/- 0.82) x 10^(-11) erg/cm^2/s. Using simultaneously collected data with the spectrometer SPI of INTEGRAL the combined total spectrum yields the first evidence for a spectral break with a peak energy of 228 +65/-41 keV. There is no evidence for significant long-term time variability of the total emission. Pulsed emission is measured with ISGRI up to 160 keV. The 20-160 keV profile shows a broad double-peaked pulse with a 6.2 sigma detection significance. The total pulsed spectrum can be described with a very hard power-law shape with a photon index \\Gamma = 0.40 +/- 0.15. We performed phase-resolved spectroscopy over the total...

  6. X-Raying an Accretion Disk in Realtime: the Evolution of Ionized Reflection during a Superburst from 4U 1636-536

    CERN Document Server

    Keek, L; Kuulkers, E; Strohmayer, T E

    2014-01-01

    When a thermonuclear X-ray burst ignites on an accreting neutron star, the accretion disk undergoes sudden strong X-ray illumination, which can drive a range of processes in the disk. Observations of superbursts, with durations of several hours, provide the best opportunity to study these processes and to probe accretion physics. Using detailed models of ionized reflection, we perform time resolved spectroscopy of the superburst observed from 4U 1636-536 in 2001 with RXTE. The spectra are consistent with a blackbody reflecting off a photoionized accretion disk, with the ionization state dropping with time. The evolution of the reflection fraction indicates that the initial reflection occurs from a part of the disk at larger radius, subsequently transitioning to reflection from an inner region of the disk. Even though this superburst did not reach the Eddington limit, we find that a strong local absorber develops during the superburst. Including this event, only two superbursts have been observed by an instrum...

  7. A study of outburst ephemeris and burst properties of blackhole candidate 4U 1630-47 with ASM, MAXI and Suzaku data

    Science.gov (United States)

    Abraham, Lalitha; Agrawal, V. K.

    4U 1630-47 is a soft X-ray transient which is thought to be a blackhole candidate. This source exhibits quasi-periodic outbursts on time scales of 500-700 days. In addition to the normal outbursts which usually last for a few months, the source displays superoutbursts, lasting for one to two years, seen to recur in every 10-12 years. The outburst ephemeris has been studied previously upto 1996 outbursts. In this work we present the updated ephemeris using 16 years data obtained from All Sky Monitor (ASM) onboard RXTE and one years data from MAXI satellite. The data covers 7 outbursts seen from ASM and one outburst seen by MAXI. We study morphology of each of these outbursts. We find that most of the bursts can be classified in basic three categories: flat top, FRED (Fast Rise Exponential Decay) and triangular. We also investigate relation between burst properties with quiescent flux level using Suzaku data, a study which has not been done previously.

  8. X-RAYING AN ACCRETION DISK IN REALTIME: THE EVOLUTION OF IONIZED REFLECTION DURING A SUPERBURST FROM 4U 1636-536

    Energy Technology Data Exchange (ETDEWEB)

    Keek, L.; Ballantyne, D. R. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430 (United States); Kuulkers, E. [European Space Astronomy Centre (ESA/ESAC), Science Operations Department, E-28691 Villanueva de la Cañada, Madrid (Spain); Strohmayer, T. E., E-mail: l.keek@gatech.edu [X-Ray Astrophysics Lab, Astrophysics Science Division, NASA' s Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-12-20

    When a thermonuclear X-ray burst ignites on an accreting neutron star, the accretion disk undergoes sudden strong X-ray illumination, which can drive a range of processes in the disk. Observations of superbursts, with durations of several hours, provide the best opportunity to study these processes and to probe accretion physics. Using detailed models of X-ray reflection, we perform time resolved spectroscopy of the superburst observed from 4U 1636-536 in 2001 with the Rossi X-Ray Timing Explorer. The spectra are consistent with a blackbody reflecting off a photoionized accretion disk, with the ionization state dropping with time. The evolution of the reflection fraction indicates that the initial reflection occurs from a part of the disk at larger radius, subsequently transitioning to reflection from an inner region of the disk. Even though this superburst did not reach the Eddington limit, we find that a strong local absorber develops during the superburst. Including this event, only two superbursts have been observed by an instrument with sufficient collecting area to allow for this analysis. It highlights the exciting opportunity for future X-ray observatories to investigate the processes in accretion disks when illuminated by superbursts.

  9. Spectral and Timing Evolution of the Black Hole X-ray Nova 4U 1543-47 During its 2002 Outburst

    CERN Document Server

    Park, S Q; McClintock, J E; Remillard, R A; Orosz, J A; Shrader, C R; Hunstead, R W; Campbell-Wilson, D; Ishwara-Chandra, C H; Rao, A P; Rupen, M P

    2003-01-01

    We present an X-ray spectral and timing analysis of 4U 1543-47 during its 2002 outburst based on 49 pointed observations obtained using the Rossi X-ray Timing Explorer (RXTE). The outburst reached a peak intensity of 4.2 Crab in the 2-12 keV band and declined by a factor of 32 throughout the month-long observation. A 21.9 +- 0.6 mJy radio flare was detected at 1026.75 MHz two days before the X-ray maximum; the radio source was also detected late in the outburst, after the X-ray source entered the low hard state. The X-ray light curve exhibits the classic shape of a rapid rise and an exponential decay. The spectrum is soft and dominated by emission from the accretion disk. The continuum is fit with a multicolor disk blackbody (kT_{max} = 1.04 keV) and a power-law (Gamma ~ 2.7). Midway through the decay phase, a strong low-frequency QPO (nu = 7.3-8.1 Hz) was present for several days. The spectra feature a broad Fe K alpha line that is asymmetric, suggesting that the line is due to relativistic broadening rather...

  10. Binary dynamics near a massive black hole

    CERN Document Server

    Hopman, Clovis

    2009-01-01

    We analyze the dynamical evolution of binary stars that interact with a static background of single stars in the environment of a massive black hole (MBH). All stars are considered to be single mass, Newtonian point particles. We follow the evolution of the energy E and angular momentum J of the center of mass of the binaries with respect to the MBH, as well as their internal semi-major axis a, using a Monte Carlo method. For a system like the Galactic center, the main conclusions are the following: (1) The binary fraction can be of the order of a few percent outside 0.1 pc, but decreases quickly closer to the MBH. (2) Within ~0.1 pc, binaries can only exist on eccentric orbits with apocenters much further away from the MBH. (3) Far away from the MBH, loss-cone effects are the dominant mechanism that disrupts binaries with internal velocities close to the velocity dispersion. Closer to the MBH, three-body encounters are more effective in disrupting binaries. (4) The rate at which hard binaries become tighter ...

  11. Interrupted Binary Mass Transfer in Star Clusters

    CERN Document Server

    Leigh, Nathan W C; Toonen, Silvia

    2016-01-01

    Binary mass transfer is at the forefront of some of the most exciting puzzles of modern astrophysics, including Type Ia supernovae, gamma-ray bursts, and the formation of most observed exotic stellar populations. Typically, the evolution is assumed to proceed in isolation, even in dense stellar environments such as star clusters. In this paper, we test the validity of this assumption via the analysis of a large grid of binary evolution models simulated with the SeBa code. For every binary, we calculate analytically the mean time until another single or binary star comes within the mean separation of the mass-transferring binary, and compare this time-scale to the mean time for stable mass transfer to occur. We then derive the probability for each respective binary to experience a direct dynamical interruption. The resulting probability distribution can be integrated to give an estimate for the fraction of binaries undergoing mass transfer that are expected to be disrupted as a function of the host cluster pro...

  12. The origin of very wide binary stars

    CERN Document Server

    Kouwenhoven, M B N; Davies, Melvyn B; Parker, Richard J; Kroupa, P; Malmberg, D

    2011-01-01

    A large population of fragile, wide (> 1000 AU) binary systems exists in the Galactic field and halo. These wide binary stars cannot be primordial because of the high stellar density in star forming regions, while formation by capture in the Galactic field is highly improbable. We propose that these binary systems were formed during the dissolution phase of star clusters (see Kouwenhoven et al. 2010, for details). Stars escaping from a dissolving star cluster can have very similar velocities, which can lead to the formation of a wide binary systems. We carry out N-body simulations to test this hypothesis. The results indicate that this mechanism explains the origin of wide binary systems in the Galaxy. The resulting wide binary fraction and semi-major axis distribution depend on the initial conditions of the dissolving star cluster, while the distributions in eccentricity and mass ratio are universal. Finally, since most stars are formed in (relatively tight) primordial binaries, we predict that a large fract...

  13. Interrupted Binary Mass Transfer in Star Clusters

    Science.gov (United States)

    Leigh, Nathan W. C.; Geller, Aaron M.; Toonen, Silvia

    2016-02-01

    Binary mass transfer (MT) is at the forefront of some of the most exciting puzzles of modern astrophysics, including SNe Ia, gamma-ray bursts, and the formation of most observed exotic stellar populations. Typically, the evolution is assumed to proceed in isolation, even in dense stellar environments such as star clusters. In this paper, we test the validity of this assumption via the analysis of a large grid of binary evolution models simulated with the SeBa code. For every binary, we calculate analytically the mean time until another single or binary star comes within the mean separation of the mass-transferring binary, and compare this timescale to the mean time for stable MT to occur. We then derive the probability for each respective binary to experience a direct dynamical interruption. The resulting probability distribution can be integrated to give an estimate for the fraction of binaries undergoing MT that are expected to be disrupted as a function of the host cluster properties. We find that for lower-mass clusters (≲ {10}4 {M}⊙ ), on the order of a few to a few tens of percent of binaries undergoing MT are expected to be interrupted by an interloping single, or more often binary, star, over the course of the cluster lifetime, whereas in more massive globular clusters we expect \\ll 1% to be interrupted. Furthermore, using numerical scattering experiments performed with the FEWBODY code, we show that the probability of interruption increases if perturbative fly-bys are considered as well, by a factor ˜2.

  14. Fast algorithms for generating binary holograms

    CERN Document Server

    Stuart, Dustin; Kuhn, Axel

    2014-01-01

    We describe three algorithms for generating binary-valued holograms. Our methods are optimised for producing large arrays of tightly focussed optical tweezers for trapping particles. Binary-valued holograms allow us to use a digital mirror device (DMD) as the display element, which is much faster than other alternatives. We describe how our binary amplitude holograms can be used to correct for phase errors caused by optical aberrations. Furthermore, we compare the speed and accuracy of the algorithms for both periodic and arbitrary arrangements of traps, which allows one to choose the ideal scheme depending on the circumstances.

  15. Discovery of a 2 Kpc Binary Quasar

    OpenAIRE

    Shields, G. A.; Junkkarinen, V.; Beaver, E. A.; Burbidge, E. M.; Cohen, R. D.; Hamann, F.; Lyons, R. W.

    2001-01-01

    LBQS 0103$-$2753 is a binary quasar with a separation of only 0.3 arcsec. The projected spacing of 2.3 kpc at the distance of the source (z = 0.848) is much smaller than that of any other known binary QSO. The binary nature is demonstrated by the very different spectra of the two components and the low probability of a chance pairing. LBQS 0103$-$2753 presumably is a galaxy merger with a small physical separation between the two supermassive black holes. Such objects may provide important con...

  16. Binary Cu-Zr Bulk Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    TANG Mei-Bo; ZHAO De-Qian; PAN Ming-Xiang; WANG Wei-Hua

    2004-01-01

    @@ We report that bulk metallic glasses (BMGs) can be produced up to 2 mm by a copper mould casting in Cux Zr1-x binary alloy with a wide glass forming composition range (45 < x < 60 at.%). We find that the formation mechanism for the binary Cu-Zr binary BMG-forming alloy is obviously different from that of the intensively studied multicomponent BMGs. Our results demonstrate that the criteria for the multicomponent alloys with composition near deep eutectic and strong liquid behaviour are no longer the major concern for designing BMGs.

  17. Dynamical mass transfer in cataclysmic binaries

    Science.gov (United States)

    Melia, Fulvio; Lamb, D. Q.

    1987-01-01

    When a binary comes into contact and mass transfer begins, orbital angular momentum is stored in the accretion disk until the disk couples tidally to the binary system. Taam and McDermott (1987) have suggested that this leads to unstable dynamical mass transfer in many cataclysmic variables in which mass transfer would otherwise be stable, and that it explains the gap between 2 and 3 h in the orbital period distribution of these systems. Here the consequences of this hypothesis for the evolution of cataclysmic binaries are explored. It is found that systems coming into contact longward of the period gap undergo one or more episodes of dynamical mass transfer.

  18. Blind iterative deconvolution of binary star images

    CERN Document Server

    Saha, S K

    1997-01-01

    The technique of Blind Iterative De-convolution (BID) was used to remove the atmospherically induced point spread function (PSF) from short exposure images of two binary stars, HR 5138 and HR 5747 obtained at the cassegrain focus of the 2.34 meter Vainu Bappu Telescope(VBT), situated at Vainu Bappu Observatory (VBO), Kavalur. The position angles and separations of the binary components were seen to be consistent with results of the auto-correlation technique, while the Fourier phases of the reconstructed images were consistent with published observations of the binary orbits.

  19. Division Unit for Binary Integer Decimals

    DEFF Research Database (Denmark)

    Lang, Tomas; Nannarelli, Alberto

    2009-01-01

    -recurrence algorithm to BID representation and implement the division unit in standard cell technology. The implementation of the proposed BID division unit is compared to that of a BCD based unit implementing the same algorithm. The comparison shows that for normalized operands the BID unit has the same latency......In this work, we present a radix-10 division unit that is based on the digit-recurrence algorithm and implements binary encodings (binary integer decimal or BID) for significands. Recent decimal division designs are all based on the binary coded decimal (BCD) encoding. We adapt the radix-10 digit...

  20. Busting Up Binaries: Encounters Between Compact Binaries and a Supermassive Black Hole

    CERN Document Server

    Addison, Eric; Larson, Shane

    2015-01-01

    Given the stellar density near the galactic center, close encounters between compact object binaries and the supermassive black hole are a plausible occurrence. We present results from a numerical study of close to 13 million such encounters. Consistent with previous studies, we corroborate that, for binary systems tidally disrupted by the black hole, the component of the binary remaining bound to the hole has eccentricity ~ 0.97 and circularizes dramatically by the time it enters the classical LISA band. Our results also show that the population of surviving binaries merits attention. These binary systems experience perturbations to their internal orbital parameters with potentially interesting observational consequences. We investigated the regions of parameter space for survival and estimated the distribution of orbital parameters post-encounter. We found that surviving binaries harden and their eccentricity increases, thus accelerating their merger due gravitational radiation emission and increasing the p...

  1. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Haghighipour, Nader [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Kaltenegger, Lisa [MPIA, Koenigstuhl 17, Heidelberg, D-69117 (Germany)

    2013-11-10

    We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results.

  2. Binary neutron star merger simulations

    Energy Technology Data Exchange (ETDEWEB)

    Bruegmann, Bernd [Jena Univ. (Germany)

    2016-11-01

    Our research focuses on the numerical tools necessary to solve Einstein's equations. In recent years we have been particularly interested in spacetimes consisting of two neutron stars in the final stages of their evolution. Because of the emission of gravitational radiation, the objects are driven together to merge; the emitted gravitational wave signal is visualized. This emitted gravitational radiation carries energy and momentum away from the system and contains information about the system. Late last year the Laser Interferometer Gravitational-wave Observatory (LIGO) began searches for these gravitational wave signals at a sensitivity at which detections are expected. Although such systems can radiate a significant amount of their total mass-energy in gravitational waves, the gravitational wave signals one expects to receive on Earth are not strong, since sources of gravitational waves are often many millions of light years away. Therefore one needs accurate templates for the radiation one expects from such systems in order to be able to extract them out of the detector's noise. Although analytical models exist for compact binary systems when the constituents are well separated, we need numerical simulation to investigate the last orbits before merger to obtain accurate templates and validate analytical approximations. Due to the strong nonlinearity of the equations and the large separation of length scales, these simulations are computationally demanding and need to be run on large supercomputers. When matter is present the computational cost as compared to pure black hole (vacuum) simulations increases even more due to the additional matter fields. But also more interesting astrophysical phenomena can happen. In fact, there is the possibility for a strong electromagnetic signal from the merger (e.g., a short gamma-ray burst or lower-energy electromagnetic signatures from the ejecta) and significant neutrino emission. Additionally, we can expect that

  3. New Insights into X-ray Binaries

    CERN Document Server

    Casares, Jorge

    2009-01-01

    X-ray binaries are excellent laboratories to study collapsed objects. On the one hand, transient X-ray binaries contain the best examples of stellar-mass black holes while persistent X-ray binaries mostly harbour accreting neutron stars. The determination of stellar masses in persistent X-ray binaries is usually hampered by the overwhelming luminosity of the X-ray heated accretion disc. However, the discovery of high-excitation emission lines from the irradiated companion star has opened new routes in the study of compact objects. This paper presents novel techniques which exploits these irradiated lines and summarises the dynamical masses obtained for the two populations of collapsed stars: neutron stars and black holes.

  4. A mesoscopic model for binary fluids

    CERN Document Server

    Echeverria, C; Alvarez-Llamoza, O; Orozco-Guillén, E E; Morales, M; Cosenza, M G

    2016-01-01

    We propose a model to study symmetric binary fluids, based in the mesoscopic molecular simulation technique known as multiparticle collision, where space and state variables are continuous while time is discrete. We include a repulsion rule to simulate segregation processes that does not require the calculation of the interaction forces between particles, thus allowing the description of binary fluids at a mesoscopic scale. The model is conceptually simple, computationally efficient, maintains Galilean invariance, and conserves the mass and the energy in the system at micro and macro scales; while momentum is conserved globally. For a wide range of temperatures and densities, the model yields results in good agreement with the known properties of binary fluids, such as density profile, width of the interface, phase separation and phase growth. We also apply the model to study binary fluids in crowded environments with consistent results.

  5. Red-giant stars in eccentric binaries

    Directory of Open Access Journals (Sweden)

    Beck P. G.

    2015-01-01

    Full Text Available The unparalleled photometric data obtained by NASA’s Kepler Space Telescope has led to improved understanding of red-giant stars and binary stars. We discuss the characterization of known eccentric system, containing a solar-like oscillating red-giant primary component. We also report several new binary systems that are candidates for hosting an oscillating companion. A powerful approach to study binary stars is to combine asteroseimic techniques with light curve fitting. Seismology allows us to deduce the properties of red giants. In addition, by modeling the ellipsoidal modulations we can constrain the parameters of the binary system. An valuable independent source are ground-bases, high-resolution spectrographs.

  6. Binary Biometric Representation through Pairwise Polar Quantization

    NARCIS (Netherlands)

    Chen, Chun; Veldhuis, Raymond; Tistarelli, M.; Nixon, M.

    2009-01-01

    Binary biometric representations have great significance for data compression and template protection. In this paper, we introduce pairwise polar quantization. Furthermore, aiming to optimize the discrimination between the genuine Hamming distance (GHD) and the imposter Hamming distance (IHD), we pr

  7. Searching for Pulsars in Close Binary Systems

    CERN Document Server

    Jouteux, S; Stappers, B W; Jonker, P; Van der Klis, M

    2001-01-01

    We present a detailed mathematical analysis of the Fourier response of binary pulsar signals whose frequencies are modulated by circular orbital motion. The fluctuation power spectrum of such signals is found to be \

  8. RXTE/ASM and Swift/BAT observations of spectral transitions in bright X-ray binaries in 2005-2010

    Science.gov (United States)

    Tang, Jing; Yu, Wen-Fei; Yan, Zhen

    2011-04-01

    We have studied X-ray spectral state transitions that can be seen in the long-term monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert Telescope (BAT) onboard Swift during a period of five years from 2005 to 2010. We have applied a program to automatically identify the hard-to-soft (H-S) spectral state transitions in the bright X-ray binaries monitored by the ASM and the BAT. In total, we identified 128 hard-to-soft transitions, of which 59 occurred after 2008. We also determined the transition fluxes and the peak fluxes of the following soft states, updated the measurements of the luminosity corresponding to the H-S transition and the peak luminosity of the following soft state in about 30 bright persistent and transient black hole and neutron star binaries following Yu & Yan, and found the luminosity correlation and the luminosity range of spectral transitions in data between 2008-2010 are about the same as those derived from data before 2008. This further strengthens the idea that the luminosity at which the H-S spectral transition occurs in the Galactic X-ray binaries is determined by non-stationary accretion parameters such as the rate-of-change of the mass accretion rate rather than the mass accretion rate itself. The correlation is also found to hold in data of individual sources 4U 1608-52 and 4U 1636-53.

  9. Tidal capture formation of Low Mass X-Ray Binaries from wide binaries in the field

    CERN Document Server

    Michaely, Erez

    2015-01-01

    We present a potentially efficient dynamical formation scenario for Low Mass X-ray Binaries (LMXBs) in the field, focusing on black-hole (BH) LMXBs. In this formation channel LMXBs are formed from wide binaries $(>1000$ AU) with a BH component and a stellar companion. The wide binary is perturbed by fly-by's of field stars and its orbit random-walks and changes over time. This diffusion process can drive the binary into a sufficiently eccentric orbit such that the binary components tidally interact at peri-center and the binary evolves to become a short period binary, which eventually evolves into an LMXB. The formation rate of LMXBs through this channel mostly depends on the number of such BH wide binaries progenitors, which in turn depends on the velocity kicks imparted to BHs (or NSs) at birth. We consider several models for the formation and survival of such wide binaries, and calculate the LMXB formation rates for each model. We find that models where BHs form through direct collapse with no/little natal...

  10. Evolution of Binary Stars in Multiple-Population Globular Clusters - II. Compact Binaries

    CERN Document Server

    Hong, Jongsuk; Sollima, Antonio; McMillan, Stephen L W; D'Antona, Franca; D'Ercole, Annibale

    2016-01-01

    We present the results of a survey of N-body simulations aimed at exploring the evolution of compact binaries in multiple-population globular clusters.We show that as a consequence of the initial differences in the structural properties of the first-generation (FG) and the second-generation (SG) populations and the effects of dynamical processes on binary stars, the SG binary fraction decreases more rapidly than that of the FG population. The difference between the FG and SG binary fraction is qualitatively similar to but quantitatively smaller than that found for wider binaries in our previous investigations.The evolution of the radial variation of the binary fraction is driven by the interplay between binary segregation, ionization and ejection. Ionization and ejection counteract in part the effects of mass segregation but for compact binaries the effects of segregation dominate and the inner binary fraction increases during the cluster evolution. We explore the variation of the difference between the FG an...

  11. Dixie Valley Bottoming Binary Unit

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Dale [Terra-Gen Sierra Holdings, LLC, Reno, NV (United States)

    2014-12-21

    This binary plant is the first air cooled, high-output refrigeration based waste heat recovery cycle in the industry. Its working fluid is environmentally friendly and as such, the permits that would be required with a hydrocarbon based cycle are not necessary. The unit is largely modularized, meaning that the unit’s individual skids were assembled in another location and were shipped via truck to the plant site. The Air Cooled Condensers (ACC), equipment piping, and Balance of Plant (BOP) piping were constructed at site. This project further demonstrates the technical feasibility of using low temperature brine for geothermal power utilization. The development of the unit led to the realization of low temperature, high output, and environmentally friendly heat recovery systems through domestic research and engineering. The project generates additional renewable energy, resulting in cleaner air and reduced carbon dioxide emissions. Royalty and tax payments to governmental agencies will increase, resulting in reduced financial pressure on local entities. The major components of the unit were sourced from American companies, resulting in increased economic activity throughout the country.

  12. Binary module test. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Schilling, J.R.; Colley, T.C.; Pundyk, J.

    1980-12-01

    The objective of this project was to design and test a binary loop module representative of and scaleable to commercial size units. The design was based on state-of-the-art heat exchanger technology, and the purpose of the tests was to confirm performance of a supercritical boiling cycle using isobutane and a mixture of isobutane and isopentane as the secondary working fluid. The module was designed as one percent of a 50 MW unit. It was installed at Magma Power's East Mesa geothermal field and tested over a period of approximately 4 months. Most of the test runs were with isobutane but some data were collected for hydrocarbon mixtures. The results of the field tests are reported. In general these results indicate reasonably good heat balances and agreement with overall heat transfer coefficients calculated by current stream analysis methods and available fluid property data; however, measured pressure drops across the heat exchangers were 20 percent higher than estimated. System operation was stable under all conditions tested.

  13. Near-Optimal Compressive Binary Search

    OpenAIRE

    Malloy, Matthew L.; Nowak, Robert D.

    2012-01-01

    We propose a simple modification to the recently proposed compressive binary search. The modification removes an unnecessary and suboptimal factor of log log n from the SNR requirement, making the procedure optimal (up to a small constant). Simulations show that the new procedure performs significantly better in practice as well. We also contrast this problem with the more well known problem of noisy binary search.

  14. Statistical pattern classification with binary variables.

    Science.gov (United States)

    Young, T Y; Liu, P S; Rondon, R J

    1981-02-01

    Binary random variables are regarded as random vectors in a binary-field (modulo-2) linear vector space. A characteristic function is defined and related results derived using this formulation. Minimax estimation of probability distributions using an entropy criterion is investigated, which leads to an A-distribution and bilinear discriminant functions. Nonparametric classification approaches using Hamming distances and their asymptotic properties are discussed. Experimental results are presented.

  15. Binary compact object inspiral: Detection expectations

    Indian Academy of Sciences (India)

    Vassiliki Kalogera

    2004-10-01

    We review the current estimates of binary compact object inspiral rates in particular in view of the recently discovered highly relativistic binary pulsar J0737-3039. One of the robust results is that, because of this discovery, the rate estimates for binary neutron stars have increased by a factor of 6-7 independent of any uncertainties related to the pulsar population properties. This rate increase has dramatic implications for gravitational wave detectors. For initial LIGO, the most probable detection rates for double neutron star (DNS) inspirals is 1 event/(5{250) yr; at 95% confidence we obtain rates up to 1/1.5 yr. For advanced LIGO, the most probable rates are 20-1000 events/yr. These predictions, for the first time, bring the expectations for DNS detections by initial LIGO to the astrophysically relevant regime. We also use our models to predict that the large-scale Parkes multibeam pulsar survey with acceleration searches could detect an average of three to four binary pulsars similar to those known at present. In comparison, rate estimates for binaries with black holes are derived based on binary evolution calculation, and based on the optimistic ends of the ranges, remain an important candidate for inspiral detection in the next few years. We also consider another aspect of the detectability of binary inspiral: the effect of precession on the detection efficiency of astrophysically relevant binaries. Based on our current astrophysical expectations, large tilt angles are not favored. As a result the decrease in detection rate varies rather slowly with black hole spin magnitude and is within 20-30% of the maximum possible values.

  16. The DEBCat detached eclipsing binary catalogue

    OpenAIRE

    2014-01-01

    Detached eclipsing binary star systems are our primary source of measured physical properties of normal stars. I introduce DEBCat: a catalogue of detached eclipsing binaries with mass and radius measurements to the 2% precision necessary to put useful constraints on theoretical models of stellar evolution. The catalogue was begun in 2006, as an update of the compilation by Andersen (1991). It now contains over 170 systems, and new results are added on appearance in the refereed literature. DE...

  17. An improved catalog of halo wide binary candidates

    CERN Document Server

    Allen, Christine

    2014-01-01

    We present an improved catalog of halo wide binaries, compiled from an extensive literature search. Most of our binaries stem from the common proper motion binary catalogs by Allen et al. (2004), and Chanam\\'e \\& Gould. (2004) but we have also included binaries from the lists of Ryan (1992) and Zapatero-Osorio \\& Martin (2004). All binaries were carefully checked and their distances and systemic radial velocities are included, when available. Probable membership to the halo population was tested by means of reduced proper motion diagrams for 251 candidate halo binaries. After eliminating obvious disk binaries we ended up with 211 probable halo binaries, for 150 of which radial velocities are available. We compute galactic orbits for these 150 binaries and calculate the time they spend within the galactic disk. Considering the full sample of 251 candidate halo binaries as well as several subsamples, we find that the distribution of angular separations (or expected major semiaxes) follows a power law $f...

  18. Texture classification by texton: statistical versus binary.

    Directory of Open Access Journals (Sweden)

    Zhenhua Guo

    Full Text Available Using statistical textons for texture classification has shown great success recently. The maximal response 8 (Statistical_MR8, image patch (Statistical_Joint and locally invariant fractal (Statistical_Fractal are typical statistical texton algorithms and state-of-the-art texture classification methods. However, there are two limitations when using these methods. First, it needs a training stage to build a texton library, thus the recognition accuracy will be highly depended on the training samples; second, during feature extraction, local feature is assigned to a texton by searching for the nearest texton in the whole library, which is time consuming when the library size is big and the dimension of feature is high. To address the above two issues, in this paper, three binary texton counterpart methods were proposed, Binary_MR8, Binary_Joint, and Binary_Fractal. These methods do not require any training step but encode local feature into binary representation directly. The experimental results on the CUReT, UIUC and KTH-TIPS databases show that binary texton could get sound results with fast feature extraction, especially when the image size is not big and the quality of image is not poor.

  19. Spectroscopic subsystems in nearby wide binaries

    CERN Document Server

    Tokovinin, Andrei

    2015-01-01

    Radial velocity (RV) monitoring of solar-type visual binaries has been conducted at the CTIO/SMARTS 1.5-m telescope to study short-period systems. Data reduction is described, mean and individual RVs of 163 observed objects are given. New spectroscopic binaries are discovered or suspected in 17 objects, for some of them orbital periods could be determined. Subsystems are efficiently detected even in a single observation by double lines and/or by the RV difference between the components of visual binaries. The potential of this detection technique is quantified by simulation and used for statistical assessment of 96 wide binaries within 67pc. It is found that 43 binaries contain at least one subsystem and the occurrence of subsystems is equally probable in either primary or secondary components. The frequency of subsystems and their periods match the simple prescription proposed by the author (2014, AJ, 147, 87). The remaining 53 simple wide binaries with a median projected separation of 1300AU have the distri...

  20. Coronal activity from the ASAS eclipsing binaries

    CERN Document Server

    Szczygiel, D M; Paczynski, B; Pojmanski, G; Pilecki, B

    2008-01-01

    We combine the catalogue of eclipsing binaries from the All Sky Automated Survey (ASAS) with the ROSAT All Sky Survey (RASS). The combination results in 836 eclipsing binaries that display coronal activity and is the largest sample of active binary stars assembled to date. By using the (V-I) colors of the ASAS eclipsing binary catalogue, we are able to determine the distances and thus bolometric luminosities for the majority of eclipsing binaries that display significant stellar activity. A typical value for the ratio of soft X-ray to bolometric luminosity is L_X/L_bol ~ a few x 10^-4, similar to the ratio of soft X-ray to bolometric flux F_X/F_bol in the most active regions of the Sun. Unlike rapidly rotating isolated late-type dwarfs -- stars with significant outer convection zones -- a tight correlation between Rossby number and activity of eclipsing binaries is absent. We find evidence for the saturation effect and marginal evidence for the so-called "super-saturation" phenomena. Our work shows that wide-...

  1. Hard X-ray detection of the black hole candidates 4U 1630-47 and IGR J17091-3624 up to 200 keV with INTEGRAL

    DEFF Research Database (Denmark)

    Bodaghee, A.; Kuulkers, E.; Tomsick, J. A.

    2012-01-01

    During monitoring observations of the Norma and Inner Perseus Arms (rev. 1209: 2012 Sept. 6 from 18:18:23 to 22:00:21 UTC), INTEGRAL-ISGRI revealed that the accreting black hole candidates 4U 1630-47 and IGR J17091-3624 have brightened in the hard X-rays. Mosaic images consisting of 12.6 ks worth...

  2. SMM observations of gamma-ray transients. 3: A search for a broadened, redshifted positron annihilation line from the direction of the Galactic center

    Science.gov (United States)

    Harris, Michael J.; Share, Gerald H.; Leising, Mark D.

    1994-01-01

    We have searched for 1980-1988 Solar Maximum Mission gamma-ray spectrometer data for transient emission on timescales from hours to approximately 12 days of broad gamma-ray lines at energies approximately 400 keV, which were reported by the High Energy Astronomy Observatory (HEAO) 1 and SIGMA experiments from two sources lying toward the Galactic center. The lines have been interpreted as the product of the annihilation of positrons in pair plasmas surrounding the black hole candidate 1E 1740.7-2942 and the X-ray binary 1H 1822-371. Our results from a combined exposure of approximately 1.5 x 10(exp 7)s provide no convincing evidence for transient emission of this line on any timescale between approximately 9 hr and approximately 1 yr. Our 3 sigma upper limits on the line flux during approximately 12 day intervals are characteristically 4.8 x 10(exp -3) photon/sq cm/s, while for approximately 1 day intervals our 3 sigma upper limits are characteristically 4.9 x 10(exp -3) photon/sq cm/s. These results imply a duty cycle of less than 1.3% for the transient line measured from 1H 1822-371 during a approximately 3 week interval in 1977 by HEAO 1, and a duty cycle of less than or = 0.8% for the transient line detected in 1990 and 1992 from 1E 1740.7-2942 on approximately 1 day timescales by SIGMA.

  3. Spectral-Timing Analysis of the Lower kHz QPO in the Low-Mass X-ray Binary Aquila X-1

    CERN Document Server

    Troyer, Jon S

    2016-01-01

    Spectral-timing products of kilohertz quasi-periodic oscillations (kHz QPOs) in low-mass X-ray binary (LMXB) systems, including energy- and frequency-dependent lags, have been analyzed previously in 4U 1608-52, 4U 1636-53, and 4U 1728-34. Here, we study the spectral-timing properties of the lower kHz QPO of the neutron star LMXB Aquila X-1 for the first time. We compute broadband energy lags, as well as energy-dependent lags and the covariance spectrum using data from the Rossi X-ray Timing Explorer (RXTE). We find very similar characteristics to other previously studied systems, including soft lags of $\\sim$30 $\\mu$s between the 3.0 - 8.0 keV and 8.0 - 20.0 keV energy bands at the average QPO frequency. We also find lags that show a nearly monotonic trend with energy, with the highest energy photons arriving first. The covariance spectrum of the lower kHz QPO is well fit by a thermal Comptonization model, though we find a higher seed photon temperature compared to the mean spectrum, which was also seen in Pe...

  4. Selective dissolution in binary alloys

    Science.gov (United States)

    McCall, Carol Rene

    Corrosion is an important issue in the design of engineering alloys. De-alloying is an aspect of alloy corrosion related to the selective dissolution of one or more of the components in an alloy. The work reported herein focuses on the topic of de-alloying specific to single-phase binary noble metal alloy systems. The alloy systems investigated were gold-silver and gold-copper. The onset of a bulk selective dissolution process is typically marked by a critical potential whereby the more reactive component in the alloy begins dissolving from the bulk, leading to the formation of a bi-continuous solid-void morphology. The critical potential was investigated for the entire composition range of gold-silver alloys. The results presented herein include the formulation of an expression for critical potential as a function of both alloy and electrolyte composition. Results of the first investigation of underpotential deposition (UPD) on alloys are also presented herein. These results were implemented as an analytical tool to provide quantitative measurements of the surface evolution of gold during de-alloying. The region below the critical potential was investigated in terms of the compositional evolution of the alloy surface. Below the critical potential, there is a competition between the dissolution of the more reactive alloying constituent (either silver or copper) and surface diffusion of gold that serves to cover dissolution sites and prevent bulk dissolution. By holding the potential at a prescribed value below the critical potential, a time-dependent gold enrichment occurs on the alloy surface leading to passivation. A theoretical model was developed to predict the surface enrichment of gold based on the assumption of layer-by-layer dissolution of the more reactive alloy constituent. The UPD measurements were used to measure the time-dependent surface gold concentration and the results agreed with the predictions of the theoretical model.

  5. Exploring the Birth of Binary Stars

    Science.gov (United States)

    Kohler, Susanna

    2016-08-01

    More than half of all stars are thought to be in binary or multiple star systems. But how do these systems form? The misaligned spins of some binary protostars might provide a clue.Two Formation ModelsIts hard to tell how multiple-star systems form, since these systems are difficult to observe in their early stages. But based on numerical simulations, there are two proposed models for the formation of stellar binaries:Turbulent fragmentationTurbulence within a single core leads to multiple dense clumps. These clumps independently collapse to form stars that orbit each other.Disk fragmentationGravitational instabilities in a massive accretion disk cause the formation of a smaller, secondary disk within the first, resulting in two stars that orbit each other.Log column density for one of the authors simulated binary systems, just after the formation of two protostars. Diamonds indicate the protostar positions. [Adapted from Offner et al. 2016]Outflows as CluesHow can we differentiate between these formation mechanisms? Led by Stella Offner (University of Massachusetts), a team of scientists has suggested that the key isto examine the alignment of the stars protostellar outflows jets that are often emitted from the poles of young, newly forming stars.Naively, wed expect that disk fragmentation would produce binary stars with common angular momentum. As the stars spins would be aligned, they would therefore also launch protostellar jets that were aligned with each other. Turbulent fragmentation, on the other hand, would cause the stars to have independent angular momentum. This would lead to randomly oriented spins, so the protostellar jets would be misaligned.Snapshots from the authors simulations. Left panel of each pair: column density; green arrows giveprotostellar spin directions. Right panel: synthetic observations produced from the simulations; cyan arrows giveprotostellar outflow directions. [Offner et al. 2016]Simulations of FragmentationIn order to better

  6. Absolute dimensions of eclipsing binaries XXVIII. BK pegasi and other F-type binaries

    DEFF Research Database (Denmark)

    Clausen, Jens Viggo; Frandsen, S.; Bruntt, H.

    2010-01-01

     stars: evolution / stars: fundamental parameters / binaries: eclipsing / stars: individual: BK¿Peg / stars: individual: BW¿Aqr / techniques: spectroscopic Udgivelsesdato: June 24...... stars: evolution / stars: fundamental parameters / binaries: eclipsing / stars: individual: BK¿Peg / stars: individual: BW¿Aqr / techniques: spectroscopic Udgivelsesdato: June 24...

  7. New spectroscopic binary companions of giant stars and updated metallicity distribution for binary systems

    CERN Document Server

    Bluhm, P; Vanzi, L; Soto, M G; Vos, J; Wittenmyer, R A; Olivares, F; Drass, H; Mennickent, R E; Vuckovic, M; Rojo, P; Melo, C H F

    2016-01-01

    We report the discovery of 24 spectroscopic binary companions to giant stars. We fully constrain the orbital solution for 6 of these systems. We cannot unambiguously derive the orbital elements for the remaining stars because the phase coverage is incomplete. Of these stars, 6 present radial velocity trends that are compatible with long-period brown dwarf companions.The orbital solutions of the 24 binary systems indicate that these giant binary systems have a wide range in orbital periods, eccentricities, and companion masses. For the binaries with restricted orbital solutions, we find a range of orbital periods of between $\\sim$ 97-1600 days and eccentricities of between $\\sim$ 0.1-0.4. In addition, we studied the metallicity distribution of single and binary giant stars. We computed the metallicity of a total of 395 evolved stars, 59 of wich are in binary systems. We find a flat distribution for these binary stars and therefore conclude that stellar binary systems, and potentially brown dwarfs, have a diffe...

  8. On the reconstruction of binary and permutation matrices under (binary) tomographic constraints

    NARCIS (Netherlands)

    Brunetti, S.; Del Lungo, A.; Gritzmann, P.; de Vries, S.

    2008-01-01

    The paper studies the problem of reconstructing binary matrices constrained by binary tomographic information. We prove new NP-hardness results that sharpen previous complexity results in the realm of discrete tomography but also allow applications to related problems for permutation matrices. Hence

  9. Towards the field binary population: Influence of orbital decay on close binaries

    CERN Document Server

    Korntreff, Christina; Pfalzner, Susanne

    2012-01-01

    Surveys of the binary populations in the solar neighbourhood have shown that the periods of G- and M-type stars are log-normally distributed. However, observations of young binary populations suggest a log-uniform distribution. Clearly some process(es) change the period distribution over time. Most stars form in star clusters, in which two important dynamical processes occur: i) gas-induced orbital decay of embedded binary systems and ii) destruction of soft binaries in three-body interactions. The emphasis here is on orbital decay which has been largely neglected so far. Using a combination of Monte-Carlo and dynamical nbody modelling it is demonstrated here that the cluster dynamics destroys the number of wide binaries, but leaves short-period binaries basically undisturbed even for a initially log-uniform distribution. By contrast orbital decay significantly reduces the number and changes the properties of short-period binaries, but leaves wide binaries largely uneffected. Until now it was unclear whether ...

  10. Birth of Massive Black Hole Binaries

    Energy Technology Data Exchange (ETDEWEB)

    Colpi, M.; /Milan Bicocca U.; Dotti, M.; /Insubria U., Como; Mayer, L.; /Zurich, ETH; Kazantzidis, S.; /KIPAC, Menlo Park

    2007-11-19

    If massive black holes (BHs) are ubiquitous in galaxies and galaxies experience multiple mergers during their cosmic assembly, then BH binaries should be common albeit temporary features of most galactic bulges. Observationally, the paucity of active BH pairs points toward binary lifetimes far shorter than the Hubble time, indicating rapid inspiral of the BHs down to the domain where gravitational waves lead to their coalescence. Here, we review a series of studies on the dynamics of massive BHs in gas-rich galaxy mergers that underscore the vital role played by a cool, gaseous component in promoting the rapid formation of the BH binary. The BH binary is found to reside at the center of a massive self-gravitating nuclear disc resulting from the collision of the two gaseous discs present in the mother galaxies. Hardening by gravitational torques against gas in this grand disc is found to continue down to sub-parsec scales. The eccentricity decreases with time to zero and when the binary is circular, accretion sets in around the two BHs. When this occurs, each BH is endowed with it own small-size ({approx}< 0.01 pc) accretion disc comprising a few percent of the BH mass. Double AGN activity is expected to occur on an estimated timescale of {approx}< 1 Myr. The double nuclear point-like sources that may appear have typical separation of {approx}< 10 pc, and are likely to be embedded in the still ongoing starburst. We note that a potential threat of binary stalling, in a gaseous environment, may come from radiation and/or mechanical energy injections by the BHs. Only short-lived or sub-Eddington accretion episodes can guarantee the persistence of a dense cool gas structure around the binary necessary for continuing BH inspiral.

  11. Massive gaseous discs around SMBH binaries: Binary decay and tidal disruptions

    Directory of Open Access Journals (Sweden)

    Brem P.

    2012-12-01

    Full Text Available We investigate the evolution of black hole binaries embedded within geometrically thin gas discs. Our results imply that such discs can produce black hole mergers for relatively low-mass binaries, and that a significant population of eccentric binaries might exist at separations of a few 0.01 pc. These binaries may be detectable due to the time-variable accretion on to the black holes. If the disc fragments, then the newly-born stars will continue driving the binary to its coalescence, although at a slower rate. Interestingly, our preliminary analysis shows that these stars will be disrupted at a rate of ∼10−4–2 · 10−5 events per year per system.

  12. Nonconservative Mass Transfer in Massive Binaries and the Formation of Wolf-Rayet+O Binaries

    CERN Document Server

    Shao, Yong

    2016-01-01

    The mass transfer efficiency during the evolution of massive binaries is still uncertain. We model the mass transfer processes in a grid of binaries to investigate the formation of Wolf-Rayet+O (WR+O) binaries, taking into account two kinds of non-conservative mass transfer models: Model I with rotation-dependent mass accretion and Model II of half mass accretion. Generally the mass transfer in Model I is more inefficient, with the average efficiency in a range of $\\sim0.2-0.7$ and $ \\lesssim0.2 $ for Case A and Case B mass transfer, respectively. We present the parameter distributions for the descendant WR+O binaries. By comparing the modeled stellar mass distribution with the observed Galactic WR+O binaries, we find that highly non-conservative mass transfer is required.

  13. Serial binary interval ratios improve rhythm reproduction

    Directory of Open Access Journals (Sweden)

    Xiang eWu

    2013-08-01

    Full Text Available Musical rhythm perception is a natural human ability that involves complex cognitive processes. Rhythm refers to the organization of events in time, and musical rhythms have an underlying hierarchical metrical structure. The metrical structure induces the feeling of a beat and the extent to which a rhythm induces the feeling of a beat is referred to as its metrical strength. Binary ratios are the most frequent interval ratio in musical rhythms. Rhythms with hierarchical binary ratios are better discriminated and reproduced than rhythms with hierarchical non-binary ratios. However, it remains unclear whether a superiority of serial binary over non-binary ratios in rhythm perception and reproduction exists. In addition, how different types of serial ratios influence the metrical strength of rhythms remains to be elucidated. The present study investigated serial binary vs. non-binary ratios in a reproduction task. Rhythms formed with exclusively binary (1:2:4:8, non-binary integer (1:3:5:6, and non-integer (1:2.3:5.3:6.4 ratios were examined within a constant meter. The results showed that the 1:2:4:8 rhythm type was more accurately reproduced than the 1:3:5:6 and 1:2.3:5.3:6.4 rhythm types, and the 1:2.3:5.3:6.4 rhythm type was more accurately reproduced than the 1:3:5:6 rhythm type. Further analyses showed that reproduction performance was better predicted by the distribution pattern of event occurrences within an inter-beat interval, than by the coincidence of events with beats, or the magnitude and complexity of interval ratios. Whereas rhythm theories and empirical data emphasize the role of the coincidence of events with beats in determining metrical strength and predicting rhythm performance, the present results suggest that rhythm processing may be better understood when the distribution pattern of event occurrences is taken into account. These results provide new insights into the mechanisms underlining musical rhythm perception.

  14. Serial binary interval ratios improve rhythm reproduction.

    Science.gov (United States)

    Wu, Xiang; Westanmo, Anders; Zhou, Liang; Pan, Junhao

    2013-01-01

    Musical rhythm perception is a natural human ability that involves complex cognitive processes. Rhythm refers to the organization of events in time, and musical rhythms have an underlying hierarchical metrical structure. The metrical structure induces the feeling of a beat and the extent to which a rhythm induces the feeling of a beat is referred to as its metrical strength. Binary ratios are the most frequent interval ratio in musical rhythms. Rhythms with hierarchical binary ratios are better discriminated and reproduced than rhythms with hierarchical non-binary ratios. However, it remains unclear whether a superiority of serial binary over non-binary ratios in rhythm perception and reproduction exists. In addition, how different types of serial ratios influence the metrical strength of rhythms remains to be elucidated. The present study investigated serial binary vs. non-binary ratios in a reproduction task. Rhythms formed with exclusively binary (1:2:4:8), non-binary integer (1:3:5:6), and non-integer (1:2.3:5.3:6.4) ratios were examined within a constant meter. The results showed that the 1:2:4:8 rhythm type was more accurately reproduced than the 1:3:5:6 and 1:2.3:5.3:6.4 rhythm types, and the 1:2.3:5.3:6.4 rhythm type was more accurately reproduced than the 1:3:5:6 rhythm type. Further analyses showed that reproduction performance was better predicted by the distribution pattern of event occurrences within an inter-beat interval, than by the coincidence of events with beats, or the magnitude and complexity of interval ratios. Whereas rhythm theories and empirical data emphasize the role of the coincidence of events with beats in determining metrical strength and predicting rhythm performance, the present results suggest that rhythm processing may be better understood when the distribution pattern of event occurrences is taken into account. These results provide new insights into the mechanisms underlining musical rhythm perception.

  15. Beyond binaries : a way forward for comparativeeducation

    Directory of Open Access Journals (Sweden)

    Marianne Larsen

    2012-09-01

    Full Text Available Binary discourses shape and produce the stories we construct about the field of comparative education. In the first part of this article, I review a set of binary discourses that have characterized social science research since the Enlightenment, including: quantitative-qualitative, nomotheticidiographic, inductive-deductive, and practice-theory. We can think of each of these binaries at opposite ends of a set of spectrums. In the second section of the paper, I show some of the ways in which these binaries have influenced the ways that we write and talk about research within the field of comparative education. I refer to the notion of binary discourses and the productive capacity of these discourses to shape our field. I then outline some critiques of these binaries to demonstrate the inherent limitations of binary discourses, and why we need to move beyond binaries in our research, and in the histories about our field. Finally, I present some tentative conclusions on ways to get ourselves out of the trap of binary thinking.Los discursos binarios moldean y producen los argumentos que construimos sobre la disciplina de la Educación Comparada. En la primera parte de este artículo, analizo un conjunto de discursos binarios que han caracterizado la investigación en Ciencias Sociales desde la Ilustración, incluyendo la cuantitativa-cualitativa, nomotética-idiográfica, inductivadeductiva, y la práctica-teoría. Podemos pensar sobre cada uno de estos discursos binarios como argumentos en los polos de un conjunto de posibilidades. En la segunda sección del artículo, revelo algunos modos en los que estos discursos binarios han influenciado las formas a través de las cuales escribimos y analizamos la investigación en el ámbito de la Educación Comparada. Analizo la noción de discursos binarios y la capacidad productiva de estos discursos de impactar nuestra ciencia. Seguidamente expongo algunas críticas de estos discursos binarios con el

  16. Planet scattering around binaries: ejections, not collisions

    Science.gov (United States)

    Smullen, Rachel A.; Kratter, Kaitlin M.; Shannon, Andrew

    2016-09-01

    Transiting circumbinary planets discovered by Kepler provide unique insight into binary star and planet formation. Several features of this new found population, for example the apparent pile-up of planets near the innermost stable orbit, may distinguish between formation theories. In this work, we determine how planet-planet scattering shapes planetary systems around binaries as compared to single stars. In particular, we look for signatures that arise due to differences in dynamical evolution in binary systems. We carry out a parameter study of N-body scattering simulations for four distinct planet populations around both binary and single stars. While binarity has little influence on the final system multiplicity or orbital distribution, the presence of a binary dramatically affects the means by which planets are lost from the system. Most circumbinary planets are lost due to ejections rather than planet-planet or planet-star collisions. The most massive planet in the system tends to control the evolution. Systems similar to the only observed multiplanet circumbinary system, Kepler-47, can arise from much more tightly packed, unstable systems. Only extreme initial conditions introduce differences in the final planet populations. Thus, we suggest that any intrinsic differences in the populations are imprinted by formation.

  17. The binary white dwarf LHS 3236

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Hugh C.; Dahn, Conard C.; Canzian, Blaise; Guetter, Harry H.; Levine, Stephen E.; Luginbuhl, Christian B.; Monet, Alice K. B.; Stone, Ronald C.; Subasavage, John P.; Tilleman, Trudy; Walker, Richard L. [US Naval Observatory, 10391 West Naval Observatory Road, Flagstaff, AZ 86001-8521 (United States); Dupuy, Trent J.; Liu, Michael C. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Hartkopf, William I. [US Naval Observatory, 3450 Massachusetts Avenue, N.W., Washington, DC 20392-5420 (United States); Ireland, Michael J. [Department of Physics and Astronomy, Macquarie University, New South Wales, NSW 2109 (Australia); Leggett, S. K., E-mail: hch@nofs.navy.mil [Gemini Observatory, 670 N. Aohoku Place, Hilo, HI 96720 (United States)

    2013-12-10

    The white dwarf LHS 3236 (WD1639+153) is shown to be a double-degenerate binary, with each component having a high mass. Astrometry at the U.S. Naval Observatory gives a parallax and distance of 30.86 ± 0.25 pc and a tangential velocity of 98 km s{sup –1}, and reveals binary orbital motion. The orbital parameters are determined from astrometry of the photocenter over more than three orbits of the 4.0 yr period. High-resolution imaging at the Keck Observatory resolves the pair with a separation of 31 and 124 mas at two epochs. Optical and near-IR photometry give a set of possible binary components. Consistency of all data indicates that the binary is a pair of DA stars with temperatures near 8000 and 7400 K and with masses of 0.93 and 0.91 M {sub ☉}; also possible is a DA primary and a helium DC secondary with temperatures near 8800 and 6000 K and with masses of 0.98 and 0.69 M {sub ☉}. In either case, the cooling ages of the stars are ∼3 Gyr and the total ages are <4 Gyr. The combined mass of the binary (1.66-1.84 M {sub ☉}) is well above the Chandrasekhar limit; however, the timescale for coalescence is long.

  18. A Model for Contact Binary Systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A model for contact binary systems is presented, which incorporates the following special features: a) The energy exchange between the components is based on the understanding that the energy exchange is due to the release of potential, kinetic and thermal energies of the exchanged mass. b) A special form of mass and angular momentum loss occurring in contact binaries is losses via the outer Lagrangian point. c) The effects of spin, orbital rotation and tidal action on the stellar structure as well as the effect of meridian circulation on the mixing of the chemical elements are considered. d) The model is valid not only for low-mass contact binaries but also for high-mass contact binaries. For illustration, we used the model to trace the evolution of a massive binary system consisting of one 12M⊙ and one 5M⊙ star. The result shows that the start and end of the contact stage fall within the semi-detached phase during which the primary continually transfers mass to the secondary. The time span of the contact stage is short and the mass transfer rate is very large. Therefore, the contact stage can be regarded as a special part of the semi-detached phase with a large mass transfer rate. Both mass loss through the outer Lagrangian point and oscillation between contact and semi-contact states can occur during the contact phase, and the effective temperatures of the primary and the secondary are almost equal.

  19. Stability of multiplanet systems in binaries

    CERN Document Server

    Marzari, F

    2016-01-01

    When exploring the stability of multiplanet systems in binaries, two parameters are normally exploited: the critical semimajor axis ac computed by Holman and Wiegert (1999) within which planets are stable against the binary perturbations, and the Hill stability limit Delta determining the minimum separation beyond which two planets will avoid mutual close encounters. Our aim is to test whether these two parameters can be safely applied in multiplanet systems in binaries or if their predictions fail for particular binary orbital configurations. We have used the frequency map analysis (FMA) to measure the diffusion of orbits in the phase space as an indicator of chaotic behaviour. First we revisited the reliability of the empirical formula computing ac in the case of single planets in binaries and we find that, in some cases, it underestimates by 10-20% the real outer limit of stability. For two planet systems, the value of Delta is close to that computed for planets around single stars, but the level of chaoti...

  20. Orbital eccentricities in primordial black holes binaries

    CERN Document Server

    Cholis, Ilias; Ali-Haïmoud, Yacine; Bird, Simeon; Kamionkowski, Marc; Muñoz, Julian B; Raccanelli, Alvise

    2016-01-01

    It was recently suggested that the merger of $\\sim30\\,M_\\odot$ primordial black holes (PBHs) may provide a significant number of events in gravitational-wave observatories over the next decade, if they make up an appreciable fraction of the dark matter. Here we show that measurement of the eccentricities of the inspiralling binary black holes can be used to distinguish these binaries from those produced by more traditional astrophysical mechanisms. These PBH binaries are formed on highly eccentric orbits and can then merge on timescales that in some cases are years or less, retaining some eccentricity in the last seconds before the merger. This is to be contrasted with massive-stellar-binary, globular-cluster, or other astrophysical origins for binary black holes (BBHs) in which the orbits have very effectively circularized by the time the BBH enters the observable LIGO window. Here we discuss the features of the gravitational-wave signals that indicate this eccentricity and forecast the sensitivity of LIGO a...

  1. Orbital eccentricities in primordial black hole binaries

    Science.gov (United States)

    Cholis, Ilias; Kovetz, Ely D.; Ali-Haïmoud, Yacine; Bird, Simeon; Kamionkowski, Marc; Muñoz, Julian B.; Raccanelli, Alvise

    2016-10-01

    It was recently suggested that the merger of ˜30 M⊙ primordial black holes (PBHs) may provide a significant number of events in gravitational-wave observatories over the next decade, if they make up an appreciable fraction of the dark matter. Here we show that measurement of the eccentricities of the inspiralling binary black holes can be used to distinguish these binaries from those produced by more traditional astrophysical mechanisms. These PBH binaries are formed on highly eccentric orbits and can then merge on time scales that in some cases are years or less, retaining some eccentricity in the last seconds before the merger. This is to be contrasted with massive-stellar-binary, globular-cluster, or other astrophysical origins for binary black holes (BBHs) in which the orbits have very effectively circularized by the time the BBH enters the observable LIGO window. Here we discuss the features of the gravitational-wave signals that indicate this eccentricity and forecast the sensitivity of LIGO and the Einstein Telescope to such effects. We show that if PBHs make up the dark matter, then roughly one event should have a detectable eccentricity given LIGO's expected sensitivity and observing time of six years. The Einstein Telescope should see O (10 ) such events after ten years.

  2. An interferometric view of binary stars

    CERN Document Server

    Boffin, Henri M J

    2016-01-01

    The study of binary stars is critical to apprehend many of the most interesting classes of stars. Moreover, quite often, the study of stars in binary systems is our only mean to constrain stellar properties, such as masses and radii. Unfortunately, a great fraction of the most interesting binaries are so compact that they can only be apprehended by high-resolution techniques, mostly by interferometry. I present some results highlighting the use of interferometry in the study of binary stars, from finding companions and deriving orbits, determining the mass and radius of stars, to studying mass transfer in symbiotic stars, and tackling luminous blue variables. In particular, I show how interferometric studies using the PIONIER instrument have allowed us to confirm a dichotomy within symbiotic stars, obtain masses of stars with a precision better than 1%, and help us find a new Eta Carinae-like system. I will also illustrate the benefits for the study of binary stars one would get from upgrading the VLT Interfe...

  3. Stacking Analysis of Binary Systems with HAWC

    Science.gov (United States)

    Brisbois, Chad; HAWC Collaboration

    2017-01-01

    Detecting binary systems at TeV energies is an important problem because only a handful of such systems are currently known. The nature of such systems is typically thought to be composed of a compact object and a massive star. The TeV emission from these systems does not obviously correspond to emission in GeV or X-ray, where many binary systems have previously been found. This study focuses on a stacking method to detect TeV emission from LS 5039, a known TeV binary, to test its efficacy in HAWC data. Stacking is a widely employed method for increasing signal to noise ratio in optical astronomy, but has never been attempted previously with HAWC. HAWC is an ideal instrument to search for TeV binaries, because of its wide field of view and high uptime. Applying this method to the entire sky may allow HAWC to detect binary sources of very short or very long periods not sensitive to current analyses. NSF, DOE, Los Alamos, Michigan Tech, CONACyt, UNAM, BUAP.

  4. The Galactic Distribution of Contact Eclipsing Binaries

    Science.gov (United States)

    Castelaz, Michael W.; Dorn, Leah; Breitfeld, Abby; Mies, Regan; Avery, Tess

    2017-01-01

    The number of eclipsing contact binaries in different galactic latitudes and longitudes show peak distributions in the number per square degree in two latitudinal zones (-30 degrees to -25 degrees and +25 degrees to +30 degrees) and large fluctuations in longitude (Huang and Wade 1966, ApJ, 143, 146). Semi-detached or detached binaries are largely concentrated in the galactic plane as shown by Paczynski et al. (MNRAS, 368, 1311), different from the distribution of contact eclipsing binaries. The differences in distributions of different types of eclipsing binaries may be related to either distances or interstellar reddening. We will present a method to calculate photometric distances of W Urase Majoris systems (W UMa; used as a proxy for contact binaries) from 2MASS J and K magnitudes and interstellar reddening models (Schlafly and Finkbeiner 2011, ApJ. 737, 103). We compare the distances to those calculated from the period-luminosity-color relationship described by Rucinski (2004, NewAR, 48, 703). The W UMa systems are taken from the General Catalog of Variable Stars.

  5. Urey Prize Lecture: Binary Minor Planets

    Science.gov (United States)

    Margot, J. L.

    2004-11-01

    The discovery of binary systems in the near-Earth, main belt, and Kuiper belt populations provides an abundance of new data that expand our knowledge of the physics and chemistry of the solar system. Binary minor planets form as a result of collisional, tidal, and capture processes that are important to study as they play major roles in the formation and evolution of planetary systems. The frequency of occurrence of such processes directly reflects the dynamical environment in the various populations. Observations of binaries provide a powerful way to measure the bulk properties of small bodies, which in turn lead to inferences about their composition and internal structure. These data may offer a rare glimpse of what physical and chemical conditions prevailed when protoplanets formed, and what subsequent evolution took place. In the case of the Kuiper Belt, the study of a handful of binaries forces us to rethink how dense and how bright these bodies are, and to significantly revise our current mass estimates for the entire population. The number of known binary minor planets has increased dramatically over the past few years, with roughly ten new discoveries each year. I will attempt to summarize recent developments, with examples drawn from my observations with the Hubble, Palomar, Keck, Arecibo and Goldstone telescopes.

  6. Debris disks in main sequence binary systems

    CERN Document Server

    Trilling, D E; Stapelfeldt, K R; Rieke, G H; Su, K Y L; Gray, R O; Corbally, C J; Bryden, G; Chen, C H; Boden, A; Beichman, C A

    2006-01-01

    We observed 69 A3-F8 main sequence binary star systems using the Multiband Imaging Photometer for Spitzer onboard the Spitzer Space Telescope. We find emission significantly in excess of predicted photospheric flux levels for 9(+4/-3)% and 40(+7/-6)% of these systems at 24 and 70 microns, respectively. Twenty two systems total have excess emission, including four systems that show excess emission at both wavelengths. A very large fraction (nearly 60%) of observed binary systems with small (<3 AU) separations have excess thermal mission. We interpret the observed infrared excesses as thermal emission from dust produced by collisions in planetesimal belts. The incidence of debris disks around main sequence A3-F8 binaries is marginally higher than that for single old AFGK stars. Whatever combination of nature (birth conditions of binary systems) and nurture (interactions between the two stars) drives the evolution of debris disks in binary systems, it is clear that planetesimal formation is not inhibited to a...

  7. X-ray reflection in oxygen-rich accretion discs of ultra-compact X-ray binaries

    CERN Document Server

    Madej, O K; Jonker, P G; Parker, M L; Ross, R; Fabian, A C; Chenevez, J

    2014-01-01

    We present spectroscopic X-ray data of two candidate ultra-compact X-ray binaries: 4U~0614+091 and 4U~1543$-$624. We confirm the presence of a broad O VIII Ly$\\alpha$ reflection line (at $\\approx18\\ \\AA$) using {\\it XMM-Newton} and {\\it Chandra} observations obtained in 2012 and 2013. The donor star in these sources is carbon-oxygen or oxygen-neon-magnesium white dwarf. Hence, the accretion disc is enriched with oxygen which makes the O VIII Ly$\\alpha$ line particularly strong. We also confirm the presence of a strong absorption edge at $\\approx14$ \\AA\\ so far interpreted in the literature as due to absorption by neutral neon in the circumstellar and interstellar medium. However, the abundance required to obtain a good fit to this edge is $\\approx3-4$ times solar, posing a problem for this interpretation. Furthermore, modeling the X-ray reflection off a carbon and oxygen enriched, hydrogen and helium poor disc with models assuming solar composition likely biases several of the best-fit parameters. In order to...

  8. Rapid Compact Binary Coalescence Parameter Estimation

    Science.gov (United States)

    Pankow, Chris; Brady, Patrick; O'Shaughnessy, Richard; Ochsner, Evan; Qi, Hong

    2016-03-01

    The first observation run with second generation gravitational-wave observatories will conclude at the beginning of 2016. Given their unprecedented and growing sensitivity, the benefit of prompt and accurate estimation of the orientation and physical parameters of binary coalescences is obvious in its coupling to electromagnetic astrophysics and observations. Popular Bayesian schemes to measure properties of compact object binaries use Markovian sampling to compute the posterior. While very successful, in some cases, convergence is delayed until well after the electromagnetic fluence has subsided thus diminishing the potential science return. With this in mind, we have developed a scheme which is also Bayesian and simply parallelizable across all available computing resources, drastically decreasing convergence time to a few tens of minutes. In this talk, I will emphasize the complementary use of results from low latency gravitational-wave searches to improve computational efficiency and demonstrate the capabilities of our parameter estimation framework with a simulated set of binary compact object coalescences.

  9. Binary Code Disassembly for Reverse Engineering

    Directory of Open Access Journals (Sweden)

    Marius Popa

    2013-01-01

    Full Text Available The disassembly of binary file is used to restore the software application code in a readable and understandable format for humans. Further, the assembly code file can be used in reverse engineering processes to establish the logical flows of the computer program or its vulnerabilities in real-world running environment. The paper highlights the features of the binary executable files under the x86 architecture and portable format, presents issues of disassembly process of a machine code file and intermediate code, disassembly algorithms which can be applied to a correct and complete reconstruction of the source file written in assembly language, and techniques and tools used in binary code disassembly.

  10. Gravitational waves from spinning eccentric binaries

    CERN Document Server

    Csizmadia, Péter; Rácz, István; Vasúth, Mátyás

    2012-01-01

    This paper is to introduce a new software called CBwaves which provides a fast and accurate computational tool to determine the gravitational waveforms yielded by generic spinning binaries of neutron stars and/or black holes on eccentric orbits. This is done within the post-Newtonian (PN) framework by integrating the equations of motion and the spin precession equations while the radiation field is determined by a simultaneous evaluation of the analytic waveforms. In applying CBwaves various physically interesting scenarios have been investigated. In particular, we have studied the appropriateness of the adiabatic approximation, and justified that the energy balance relation is indeed insensitive to the specific form of the applied radiation reaction term. By studying eccentric binary systems it is demonstrated that circular template banks are very ineffective in identifying binaries even if they possess tiny residual orbital eccentricity. In addition, by investigating the validity of the energy balance relat...

  11. Memory effect from spinning unbound binaries

    CERN Document Server

    De Vittori, Lorenzo; Gupta, Anuradha; Jetzer, Philippe

    2014-01-01

    We present a recently developed prescription to obtain ready-to-use gravitational wave (GW) polarization states for spinning compact binaries on hyperbolic orbits. We include leading order spin-orbit interactions, invoking 1.5PN-accurate quasi-Keplerian parametrization for the radial part of the orbital dynamics. We also include radiation reaction effects on $h_+$ and $h_{\\times}$ during the interaction. In the GW signals from spinning binaries there is evidence of the memory effect in both polarizations, in contrast to the non-spinning case, where only the cross polarizations exhibits non-vanishing amplitudes at infinite time. We also compute 1PN-accurate GW polarization states for non-spinning compact binaries in unbound orbits in a fully parametric way, and compare them with existing waveforms.

  12. Hybrid Black-Hole Binary Initial Data

    Science.gov (United States)

    Mundim, Bruno C.; Kelly, Bernard J.; Nakano, Hiroyuki; Zlochower, Yosef; Campanelli, Manuela

    2010-01-01

    "Traditional black-hole binary puncture initial data is conformally flat. This unphysical assumption is coupled with a lack of radiation signature from the binary's past life. As a result, waveforms extracted from evolutions of this data display an abrupt jump. In Kelly et al. [Class. Quantum Grav. 27:114005 (2010)], a new binary black-hole initial data with radiation contents derived in the post-Newtonian (PN) calculations was adapted to puncture evolutions in numerical relativity. This data satisfies the constraint equations to the 2.5PN order, and contains a transverse-traceless "wavy" metric contribution, violating the standard assumption of conformal flatness. Although the evolution contained less spurious radiation, there were undesired features; the unphysical horizon mass loss and the large initial orbital eccentricity. Introducing a hybrid approach to the initial data evaluation, we significantly reduce these undesired features."

  13. Hybrid black-hole binary initial data

    CERN Document Server

    Mundim, Bruno C; Zlochower, Yosef; Nakano, Hiroyuki; Campanelli, Manuela

    2010-01-01

    Traditional black-hole binary puncture initial data is conformally flat. This unphysical assumption is coupled with a lack of radiation signature from the binary's past life. As a result, waveforms extracted from evolutions of this data display an abrupt jump. In Kelly et al. [Class.Quant.Grav.27:114005,2010], a new binary black-hole initial data with radiation contents derived in the post-Newtonian (PN) calculation was adapted to puncture evolutions in numerical relativity. This data satisfies the constraint equations to the 2.5PN order, and contains a transverse-traceless "wavy" metric contribution, violating the standard assumption of conformal flatness. Although the evolution contained less spurious radiation, there were undesired features; the unphysical horizon mass loss and the large initial orbital eccentricity. Introducing a hybrid approach to the initial data evaluation, we significantly reduce these undesired features.

  14. Hybrid black-hole binary initial data

    Energy Technology Data Exchange (ETDEWEB)

    Mundim, Bruno C; Zlochower, Yosef; Nakano, Hiroyuki; Campanelli, Manuela [Center for Computational Relativity and Gravitation, School of Mathematical Sciences, Rochester Institute of Technology, Rochester, NY14623 (United States); Kelly, Bernard J, E-mail: bcmsma@astro.rit.edu, E-mail: bernard.j.kelly@nasa.gov, E-mail: yosef@astro.rit.edu, E-mail: nakano@astro.rit.edu, E-mail: manuela@astro.rit.edu [CRESST and Gravitational Astrophysics Laboratory, NASA/GSFC, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)

    2011-07-07

    Traditional black-hole (BH) binary puncture initial data is conformally flat. This unphysical assumption is coupled with a lack of radiation signature from the binary's past life. As a result, waveforms extracted from evolutions of this data display an abrupt jump. In Kelly et al (2010, Class. Quantum Grav. 27 114005), a new binary BH initial data with radiation content derived from post-Newtonian (PN) theory was adapted to puncture evolutions in numerical relativity. This data satisfies the constraint equations to the 2.5PN order, and contains a transverse-traceless 'wavy' metric contribution, violating the standard assumption of conformal flatness. Although the evolution contained less spurious radiation, there were undesirable features: unphysical horizon mass loss and large initial orbital eccentricity. Introducing a hybrid approach to the initial data evaluation, we significantly reduce these undesired features.

  15. The Expressive Power of Binary Submodular Functions

    CERN Document Server

    Zivny, Stanislav; Jeavons, Peter G

    2008-01-01

    It has previously been an open problem whether all Boolean submodular functions can be decomposed into a sum of binary submodular functions over a possibly larger set of variables. This problem has been considered within several different contexts in computer science, including computer vision, artificial intelligence, and pseudo-Boolean optimisation. Using a connection between the expressive power of valued constraints and certain algebraic properties of functions, we answer this question negatively. Our results have several corollaries. First, we characterise precisely which submodular functions of arity 4 can be expressed by binary submodular functions. Next, we identify a novel class of submodular functions of arbitrary arities which can be expressed by binary submodular functions, and therefore minimised efficiently using a so-called expressibility reduction to the Min-Cut problem. More importantly, our results imply limitations on this kind of reduction and establish for the first time that it cannot be...

  16. Asteroseismic modelling of the Binary HD 176465

    CERN Document Server

    Nsamba, B; Campante, T L; Reese, D R; White, T R; Hernández, A García; Jiang, C

    2016-01-01

    The detection and analysis of oscillations in binary star systems is critical in understanding stellar structure and evolution. This is partly because such systems have the same initial chemical composition and age. Solar-like oscillations have been detected by Kepler in both components of the asteroseismic binary HD 176465. We present an independent modelling of each star in this binary system. Stellar models generated using MESA (Modules for Experiments in Stellar Astrophysics) were fitted to both the observed individual frequencies and complementary spectroscopic parameters. The individual theoretical oscillation frequencies for the corresponding stellar models were obtained using GYRE as the pulsation code. A Bayesian approach was applied to find the probability distribution functions of the stellar parameters using AIMS (Asteroseismic Inference on a Massive Scale) as the optimisation code. The ages of HD 176465 A and HD 176465 B were found to be 2.81 $\\pm$ 0.48 Gyr and 2.52 $\\pm$ 0.80 Gyr, respectively. ...

  17. Gravitational Wave Physics with Binary Love Relations

    Science.gov (United States)

    Yagi, Kent; Yunes, Nicolas

    2016-03-01

    Gravitational waves from the late inspiral of neutron star binaries encode rich information about their internal structure at supranuclear densities through their tidal deformabilities. However, extracting the individual tidal deformabilities of the components of a binary is challenging with future ground-based gravitational wave interferometers due to degeneracies between them. We overcome this difficulty by finding new, approximate universal relations between the individual tidal deformabilities that depend on the mass ratio of the two stars and are insensitive to their internal structure. Such relations have applications not only to gravitational wave astrophysics, but also to nuclear physics as they improve the measurement accuracy of tidal parameters. Moreover, the relations improve our ability to test extreme gravity and perform cosmology with gravitational waves emitted from neutron star binaries.

  18. ON SELF-INVERSE BINARY MATRICES OVER THE BINARY GALOIS FIELD

    Directory of Open Access Journals (Sweden)

    Ali Muhammad Ali Rushdi

    2013-01-01

    Full Text Available An important class of square binary matrices over the simplest finite or Galois Field GF(2 is the class of involutory or Self-Inverse (SI matrices. These matrices are of significant utility in prominent engineering applications such as the study of the Preparata Transformation or the analysis of synchronous Boolean Networks. Therefore, it is essential to devise appropriate methods, not only for understanding the properties of these matrices, but also for characterizing and constructing them. We survey square binary matrices of orders 1, 2 and 3 to identify primitive SI matrices among them. Larger SI matrices are constructed as (a the direct sum, or (b the Kronecker product, of smaller ones. Illustrative examples are given to demonstrate the construction and properties of binary SI matrices. The intersection of the sets of SI and permutation binary matrices is studied. We also study higher-order SI binary matrices and describe them via recursive relations or Kronecker products. Our work culminates in an exposition of the two most common representations of Boolean functions via two types of Boolean SI matrices. A better understanding of the properties and methods of constructing SI binary matrices over GF (2 is achieved. A clearer picture is attained about the utility of binary matrices in the representation of Boolean functions.

  19. Searching for Binary Supermassive Black Holes via Variable Broad Emission Line Shifts: Low Binary Fraction

    Science.gov (United States)

    Wang, Lile; Greene, Jenny E.; Ju, Wenhua; Rafikov, Roman R.; Ruan, John J.; Schneider, Donald P.

    2017-01-01

    Supermassive black hole binaries (SMBHs) are expected to result from galaxy mergers, and thus are natural byproducts (and probes) of hierarchical structure formation in the universe. They are also the primary expected source of low-frequency gravitational wave emission. We search for binary BHs using time-variable velocity shifts in broad Mg ii emission lines of quasars with multi-epoch observations. First, we inspect velocity shifts of the binary SMBH candidates identified in Ju et al., using Sloan Digital Sky Survey spectra with an additional epoch of data that lengthens the typical baseline to ∼10 yr. We find variations in the line of sight velocity shifts over 10 yr that are comparable to the shifts observed over 1–2 yr, ruling out the binary model for the bulk of our candidates. We then analyze 1438 objects with eight-year median time baselines, from which we would expect to see velocity shifts >1000 {km} {{{s}}}-1 from sub-parsec binaries. We find only one object with an outlying velocity of 448 {km} {{{s}}}-1, indicating—based on our modeling—that ≲1% (the value varies with different assumptions) of SMBHs that are active as quasars reside in binaries with ∼0.1 pc separations. Binaries either sweep rapidly through these small separations or stall at larger radii.

  20. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. I. S-TYPE BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Kaltenegger, Lisa [MPIA, Koenigstuhl 17, D-69117 Heidelberg (Germany); Haghighipour, Nader, E-mail: kaltenegger@mpia.de [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States)

    2013-11-10

    We have developed a comprehensive methodology for calculating the boundaries of the habitable zone (HZ) of planet-hosting S-type binary star systems. Our approach is general and takes into account the contribution of both stars to the location and extent of the binary HZ with different stellar spectral types. We have studied how the binary eccentricity and stellar energy distribution affect the extent of the HZ. Results indicate that in binaries where the combination of mass-ratio and orbital eccentricity allows planet formation around a star of the system to proceed successfully, the effect of a less luminous secondary on the location of the primary's HZ is generally negligible. However, when the secondary is more luminous, it can influence the extent of the HZ. We present the details of the derivations of our methodology and discuss its application to the binary HZ around the primary and secondary main-sequence stars of an FF, MM, and FM binary, as well as two known planet-hosting binaries α Cen AB and HD 196886.

  1. VLSI binary multiplier using residue number systems

    Energy Technology Data Exchange (ETDEWEB)

    Barsi, F.; Di Cola, A.

    1982-01-01

    The idea of performing multiplication of n-bit binary numbers using a hardware based on residue number systems is considered. This paper develops the design of a VLSI chip deriving area and time upper bounds of a n-bit multiplier. To perform multiplication using residue arithmetic, numbers are converted from binary to residue representation and, after residue multiplication, the result is reconverted to the original notation. It is shown that the proposed design requires an area a=o(n/sup 2/ log n) and an execution time t=o(log/sup 2/n). 7 references.

  2. Binary Sparse Phase Retrieval via Simulated Annealing

    Directory of Open Access Journals (Sweden)

    Wei Peng

    2016-01-01

    Full Text Available This paper presents the Simulated Annealing Sparse PhAse Recovery (SASPAR algorithm for reconstructing sparse binary signals from their phaseless magnitudes of the Fourier transform. The greedy strategy version is also proposed for a comparison, which is a parameter-free algorithm. Sufficient numeric simulations indicate that our method is quite effective and suggest the binary model is robust. The SASPAR algorithm seems competitive to the existing methods for its efficiency and high recovery rate even with fewer Fourier measurements.

  3. Spin supplementary conditions for spinning compact binaries

    CERN Document Server

    Mikóczi, Balázs

    2016-01-01

    We consider the different spin supplementary conditions (SSC) for a spinning compact binary with the leading-order spin-orbit (SO) interaction. The Lagrangian of the binary system can be constructed but it is acceleration-dependent in two cases of SSC. We rewrite the generalized Hamiltonian formalism proposed by Ostrogradsky and compute the conservative quantities and the dissipative part of relative motion during the gravitational radiation of each SSCs. We give the orbital elements and observed quantities of the SO dynamics, for instance the energy and the orbital angular momentum losses and waveforms and discuss their SSC dependence.

  4. Rotation and massive close binary evolution

    CERN Document Server

    Langer, N; Yoon, S -C; Hunter, I; Brott, I; Lennon, D J; de Mink, S E; Verheijdt, M

    2008-01-01

    We review the role of rotation in massive close binary systems. Rotation has been advocated as an essential ingredient in massive single star models. However, rotation clearly is most important in massive binaries where one star accretes matter from a close companion, as the resulting spin-up drives the accretor towards critical rotation. Here, we explore our understanding of this process, and its observable consequences. When accounting for these consequences, the question remains whether rotational effects in massive single stars are still needed to explain the observations.

  5. Speckle interferometric observations of close binary stars

    CERN Document Server

    Saha, S K; Yeswanth, L; Anbazhagan, P

    2002-01-01

    Speckle interferometric technique is employed to record a series of hundreds of short-exposure images of several close binary stars with sub-arcsecond separation through a narrow band filter at the Cassegrain focus of the 2.34 meter (m) Vainu Bappu telescope (VBT), situated at Vainu Bappu Observatory (VBO), Kavalur, India. The data are recorded sequentially by a Peltier-cooled intensified CCD camera with 10 ms exposure. The auto-correlation method is applied to determine the angular separations and position angles of these binary systems.

  6. Photometric Solutions of Some Contact ASAS Binaries

    CERN Document Server

    Gezer, I

    2015-01-01

    We present the first light curve solution of 6 contact binary systems which are chosen from the ASAS catalog. The photometric elements and the estimated absolute parameters of all systems are obtained with the light curve analyses. We calculated the values of degree of contact for the systems. The location of the targets on the Hertzsprung-Russell diagram and the mass-radius plane is compared to the other well-known contact binaries and the evolutionary status of the systems are also discussed.

  7. Photometric solutions of some contact ASAS binaries

    Science.gov (United States)

    Gezer, İ.; Bozkurt, Z.

    2016-04-01

    We present the first light curve solution of 6 contact binary systems which are chosen from the ASAS catalog. The photometric elements and the estimated absolute parameters of all systems are obtained with the light curve analyses. We calculated the values of degree of contact for the systems. The location of the targets on the Hertzsprung-Russell diagram and the mass-radius plane is compared to the other well-known contact binaries and the evolutionary status of the systems are also discussed.

  8. All optical binary delta-sigma modulator

    Science.gov (United States)

    Sayeh, Mohammad R.; Siahmakoun, Azad

    2005-09-01

    This paper describes a novel A/D converter called "Binary Delta-Sigma Modulator" (BDSM) which operates only with nonnegative signal with positive feedback and binary threshold. This important modification to the conventional delta-sigma modulator makes the high-speed (>100GHz) all-optical implementation possible. It has also the capability to modify its own sampling frequency as well as its input dynamic range. This adaptive feature helps designers to optimize the system performance under highly noisy environment and also manage the power consumption of the A/D converters.

  9. Pulsations in close binaries: challenges and opportunities

    Directory of Open Access Journals (Sweden)

    Maceroni C.

    2015-01-01

    Full Text Available CoRoT and Kepler provided a precious by-product: a number of eclipsing binaries containing variable stars and, among these, non-radial pulsators. This providential occurrence allows combining independent information from two different phenomena whose synergy yields scientific results well beyond those from the single sources. In particular, the analysis of pulsations in eclipsing binary components throws light on the internal structure of the pulsating star, on the system evolution, and on the role of tidal forces in exciting the oscillations. The case study of the Kepler target KIC 3858884 is illustrative of the difficulties of analysis and of the achievements in this rapidly developing field.

  10. Microlensing Binaries with Candidate Brown Dwarf Companions

    DEFF Research Database (Denmark)

    Shin, I.-G; Han, C.; Gould, A.

    2012-01-01

    Brown dwarfs are important objects because they may provide a missing link between stars and planets, two populations that have dramatically different formation histories. In this paper, we present the candidate binaries with brown dwarf companions that are found by analyzing binary microlensing...... masses of the brown dwarf companions are 0.02 ± 0.01 M⊙ and 0.019 ± 0.002 M⊙ for MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149, respectively, and both companions are orbiting low-mass M dwarf host stars. More microlensing brown dwarfs are expected to be detected as the number of lensing events...

  11. Apsidal motion in eclipsing binary GG Orionis

    Science.gov (United States)

    Yilan, E.; Bulut, I.

    2016-03-01

    The study of apsidal motion in binary stars with eccentric orbit is well known as an important source of information for the stellar internal structure as well as the possibility of verification of general relativity. In this study, the apsidal motion of the eccentric eclipsing binary GG Ori (P = 6.631 days, e = 0.22) has been analyzed using the times of minimum light taken from the literature and databases and the elements of apsidal motion have been computed. The method described by Giménez and García-Pelayo (1983) has been used for the apsidal motion analysis.

  12. Auto-correlation of Binary stars

    CERN Document Server

    Saha, S K

    2001-01-01

    Speckle interferometric technique is used to record a series of short exposure images of several close binary stars with sub-arcsecond separation through a narrow band filter centred at H$\\alpha$ at the Cassegrain focus of the 2.34 meter Vainu Bappu telescope (VBT), situated at Vainu Bappu Observatory (VBO), Kavalur. The auto-correlation method is developed under Image Reduction Analysis Facility (IRAF). Wiener filter is included in the programme to eliminate spurious high frequency contributions; a few sets of data provide the optimised results. The auto-correlated image of these stars gives the separation of the binary components.

  13. The DEBCat detached eclipsing binary catalogue

    CERN Document Server

    Southworth, John

    2014-01-01

    Detached eclipsing binary star systems are our primary source of measured physical properties of normal stars. I introduce DEBCat: a catalogue of detached eclipsing binaries with mass and radius measurements to the 2% precision necessary to put useful constraints on theoretical models of stellar evolution. The catalogue was begun in 2006, as an update of the compilation by Andersen (1991). It now contains over 170 systems, and new results are added on appearance in the refereed literature. DEBCat is available at: http://www.astro.keele.ac.uk/jkt/debcat/

  14. Winds from disks in compact binaries

    Energy Technology Data Exchange (ETDEWEB)

    Mauche, C.W.

    1993-10-27

    We herein present an observational and theoretical review of the winds of compact binaries. After a brief consideration of the accretion disk coronae and winds of X-ray binaries, the review concentrates on the winds of cataclysmic variables (CVs). Specifically, we consider the related problems of the geometry and mass-loss rate of the winds of CVs, their ionization state and variability, and the results from studies of eclipsing CVs. Finally, the properties of bona fide accretion disk wind models are reviewed.

  15. Elucidating the True Binary Fraction of VLM Stars and Brown Dwarfs with Spectral Binaries

    Science.gov (United States)

    Bardalez Gagliuffi, Daniella; Burgasser, Adam J.; Gelino, Christopher R.; SAHLMANN, JOHANNES; Schmidt, Sarah J.; Gagne, Jonathan; Skrzypek, Nathalie

    2017-01-01

    The very lowest-mass (VLM) stars and brown dwarfs are found in abundance in nearly all Galactic environments, yet their formation mechanism(s) remain an open question. One means of testing current formation theories is to use multiplicity statistics. The majority of VLM binaries have been discovered through direct imaging, and current angular resolution limits (0.05”-0.1") are coincident with the 1-4 AU peak in the projected separation distribution of known systems, suggesting an observational bias. I have developed a separation-independent method to detect T dwarf companions to late-M/early-L dwarfs by identifying methane absorption in their unresolved, low-resolution, near-infrared spectra using spectral indices and template fitting. Over 60 spectral binary candidates have been identified with this and comparable methods. I discuss follow-up observations, including laser-guide star adaptive optics imaging with Keck/NIRC2, which have confirmed 9 systems; and radial velocity and astrometric monitoring observations that have confirmed 7 others. The direct imaging results indicate a resolved binary fraction of 18%, coincident with current estimates of the VLM binary fraction; however, our sample contained 5 previously confirmed binaries, raising its true binary fraction to 47%. To more accurately measure the true VLM binary fraction, I describe the construction of an unbiased, volume-limited, near-infrared spectral sample of M7-L5 dwarfs within 25 pc, of which 4 (1%) are found to be spectral binary candidates. I model the complex selection biases of this method through a population simulation, set constraints on the true binary fraction as traced by these systems, and compare to the predictions of current formation theories. I also describe how this method may be applied to conduct a separation-unbiased search for giant exoplanets orbiting young VLM stars and brown dwarfs.

  16. Neutron-Star-Black-Hole Binaries Produced by Binary-Driven Hypernovae.

    Science.gov (United States)

    Fryer, Chris L; Oliveira, F G; Rueda, J A; Ruffini, R

    2015-12-01

    Binary-driven hypernovae (BdHNe) within the induced gravitational collapse paradigm have been introduced to explain energetic (E_{iso}≳10^{52}  erg), long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe). The progenitor is a tight binary composed of a carbon-oxygen (CO) core and a neutron-star (NS) companion, a subclass of the newly proposed "ultrastripped" binaries. The CO-NS short-period orbit causes the NS to accrete appreciable matter from the SN ejecta when the CO core collapses, ultimately causing it to collapse to a black hole (BH) and producing a GRB. These tight binaries evolve through the SN explosion very differently than compact binaries studied in population synthesis calculations. First, the hypercritical accretion onto the NS companion alters both the mass and the momentum of the binary. Second, because the explosion time scale is on par with the orbital period, the mass ejection cannot be assumed to be instantaneous. This dramatically affects the post-SN fate of the binary. Finally, the bow shock created as the accreting NS plows through the SN ejecta transfers angular momentum, braking the orbit. These systems remain bound even if a large fraction of the binary mass is lost in the explosion (well above the canonical 50% limit), and even large kicks are unlikely to unbind the system. Indeed, BdHNe produce a new family of NS-BH binaries unaccounted for in current population synthesis analyses and, although they may be rare, the fact that nearly 100% remain bound implies that they may play an important role in the compact merger rate, important for gravitational waves that, in turn, can produce a new class of ultrashort GRBs.

  17. Accretion-powered Compact Binaries

    Science.gov (United States)

    Mauche, Christopher W.

    2003-12-01

    Preface; The workshop logo; A short history of the CV workshop F. A. Córdova; Part I. Observations: 1. Low mass x-ray binaries A. P. Cowley, P. C. Schmidtke, D. Crampton, J. B. Hutchings, C. A. Haswell, E. L. Robinson, K. D. Horne, H. M. Johnston, S. R. Kulkarni, S. Kitamoto, X. Han, R. M. Hjellming, R. M. Wagner, S. L. Morris, P. Hertz, A. N. Parmar, L. Stella, P. Giommi, P. J. Callanan, T. Naylor, P. A. Charles, C. D. Bailyn, J. N. Imamura, T. Steiman-Cameron, J. Kristian, J. Middleditch, L. Angelini and J. P. Noris; 2. Nonmagnetic cataclysmic variables R. S. Polidan, C. W. Mauche, R. A. Wade, R. H. Kaitchuck, E. M. Schlegel, P. A. Hantzios, R. C. Smith, J. H. Wood, F. Hessman, A. Fiedler, D. H. P. Jones, J. Casares, P. A. Charles, J. van Paradijs, E. Harlaftis, T. Naylor, G. Sonneborn, B. J. M. Hassall, K. Horne, C. A. la Dous, A. W. Shafter, N. A. Hawkins, D. A. H. Buckley, D. J. Sullivan, F. V. Hessman, V. S. Dhillon, T. R. Marsh, J. Singh, S. Seetha, F. Giovannelli, A. Bianchini, E. M. Sion, D. J. Mullan, H. L. Shipman, G. Machin, P. J. Callanan, S. B. Howell, P. Szkody, E. M. Schlegel and R. F. Webbink; 3. Magnetic cataclysmic variables C. Hellier, K. O. Mason, C. W. Mauche, G. S. Miller, J. C. Raymond, F. K. Lamb, J. Patterson, A. J. Norton, M. G. Watson, A. R. King, I. M. McHardy, H. Lehto, J. P. Osborne, E. L. Robinson, A. W. Shafter, S. Balachandran, S. R. Rosen, J. Krautter, W. Buchholz, D. A. H. Buckley, I. R. Tuoly, D. Crampton, B. Warner, R. M. Prestage, B. N. Ashoka, M. Mouchet, J. M. Bonnet-Bidaud, J. M. Hameury, P. Szkody, P. Garnavich, S. Howell, T. Kii, M. Cropper, K. Mason, J. Bailey, D. T. Wickramasinghe, L. Ferrario, K. Beuermann, A. D. Schwope, H.-C. Thomas, S. Jordan, J. Schachter, A. V. Filippenko, S. M. Kahn, F. B. S. Paerels, K. Mukai, M. L. Edgar, S. Larsson, R. F. Jameson, A. R. King, A. Silber, R. Remillard, H. Bradt, M. Ishida, T. Ohashi and G. D. Schmidt; Part II. Accretion Theory: 4. Nonmagnetic W. Kley, F. Geyer, H. Herold, H

  18. The Tarantula Massive Binary Monitoring. I. Observational campaign and OB-type spectroscopic binaries

    Science.gov (United States)

    Almeida, L. A.; Sana, H.; Taylor, W.; Barbá, R.; Bonanos, A. Z.; Crowther, P.; Damineli, A.; de Koter, A.; de Mink, S. E.; Evans, C. J.; Gieles, M.; Grin, N. J.; Hénault-Brunet, V.; Langer, N.; Lennon, D.; Lockwood, S.; Maíz Apellániz, J.; Moffat, A. F. J.; Neijssel, C.; Norman, C.; Ramírez-Agudelo, O. H.; Richardson, N. D.; Schootemeijer, A.; Shenar, T.; Soszyński, I.; Tramper, F.; Vink, J. S.

    2017-02-01

    Context. Massive binaries play a crucial role in the Universe. Knowing the distributions of their orbital parameters is important for a wide range of topics from stellar feedback to binary evolution channels and from the distribution of supernova types to gravitational wave progenitors, yet no direct measurements exist outside the Milky Way. Aims: The Tarantula Massive Binary Monitoring project was designed to help fill this gap by obtaining multi-epoch radial velocity (RV) monitoring of 102 massive binaries in the 30 Doradus region. Methods: In this paper we analyze 32 FLAMES/GIRAFFE observations of 93 O- and 7 B-type binaries. We performed a Fourier analysis and obtained orbital solutions for 82 systems: 51 single-lined (SB1) and 31 double-lined (SB2) spectroscopic binaries. Results: Overall, the binary fraction and orbital properties across the 30 Doradus region are found to be similar to existing Galactic samples. This indicates that within these domains environmental effects are of second order in shaping the properties of massive binary systems. A small difference is found in the distribution of orbital periods, which is slightly flatter (in log space) in 30 Doradus than in the Galaxy, although this may be compatible within error estimates and differences in the fitting methodology. Also, orbital periods in 30 Doradus can be as short as 1.1 d, somewhat shorter than seen in Galactic samples. Equal mass binaries (q> 0.95) in 30 Doradus are all found outside NGC 2070, the central association that surrounds R136a, the very young and massive cluster at 30 Doradus's core. Most of the differences, albeit small, are compatible with expectations from binary evolution. One outstanding exception, however, is the fact that earlier spectral types (O2-O7) tend to have shorter orbital periods than later spectral types (O9.2-O9.7). Conclusions: Our results point to a relative universality of the incidence rate of massive binaries and their orbital properties in the

  19. BROWN DWARF BINARIES FROM DISINTEGRATING TRIPLE SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Reipurth, Bo [Institute for Astronomy and NASA Astrobiology Institute University of Hawaii, 640 N. Aohoku Place, Hilo, HI 96720 (United States); Mikkola, Seppo, E-mail: reipurth@ifa.hawaii.edu, E-mail: Seppo.Mikkola@utu.fi [Tuorla Observatory, University of Turku, Väisäläntie 20, Piikkiö (Finland)

    2015-04-15

    Binaries in which both components are brown dwarfs (BDs) are being discovered at an increasing rate, and their properties may hold clues to their origin. We have carried out 200,000 N-body simulations of three identical stellar embryos with masses drawn from a Chabrier IMF and embedded in a molecular core. The bodies are initially non-hierarchical and undergo chaotic motions within the cloud core, while accreting using Bondi–Hoyle accretion. The coupling of dynamics and accretion often leads to one or two dominant bodies controlling the center of the cloud core, while banishing the other(s) to the lower-density outskirts, leading to stunted growth. Eventually each system transforms either to a bound hierarchical configuration or breaks apart into separate single and binary components. The orbital motion is followed for 100 Myr. In order to illustrate 200,000 end-states of such dynamical evolution with accretion, we introduce the “triple diagnostic diagram,” which plots two dimensionless numbers against each other, representing the binary mass ratio and the mass ratio of the third body to the total system mass. Numerous freefloating BD binaries are formed in these simulations, and statistical properties are derived. The separation distribution function is in good correspondence with observations, showing a steep rise at close separations, peaking around 13 AU and declining more gently, reaching zero at separations greater than 200 AU. Unresolved BD triple systems may appear as wider BD binaries. Mass ratios are strongly peaked toward unity, as observed, but this is partially due to the initial assumptions. Eccentricities gradually increase toward higher values, due to the lack of viscous interactions in the simulations, which would both shrink the orbits and decrease their eccentricities. Most newborn triple systems are unstable and while there are 9209 ejected BD binaries at 1 Myr, corresponding to about 4% of the 200,000 simulations, this number has grown to

  20. Model-independent inference on compact-binary observations

    Science.gov (United States)

    Mandel, Ilya; Farr, Will M.; Colonna, Andrea; Stevenson, Simon; Tiňo, Peter; Veitch, John

    2017-03-01

    The recent advanced LIGO detections of gravitational waves from merging binary black holes enhance the prospect of exploring binary evolution via gravitational-wave observations of a population of compact-object binaries. In the face of uncertainty about binary formation models, model-independent inference provides an appealing alternative to comparisons between observed and modelled populations. We describe a procedure for clustering in the multidimensional parameter space of observations that are subject to significant measurement errors. We apply this procedure to a mock data set of population-synthesis predictions for the masses of merging compact binaries convolved with realistic measurement uncertainties, and demonstrate that we can accurately distinguish subpopulations of binary neutron stars, binary black holes, and mixed neutron star-black hole binaries with tens of observations.

  1. The same, but different: Stochasticity in binary destruction

    CERN Document Server

    Parker, Richard J

    2012-01-01

    Observations of binaries in clusters tend to be of visual binaries with separations of 10s - 100s au. Such binaries are 'intermediates' and their destruction or survival depends on the exact details of their individual dynamical history. We investigate the stochasticity of the destruction of such binaries and the differences between the initial and processed populations using N-body simulations. We concentrate on Orion Nebula Cluster-like clusters, where the observed binary separation distribution ranges from 62 - 620 au. We find that, starting from the same initial binary population in statistically identical clusters, the number of intermediate binaries that are destroyed after 1 Myr can vary by a factor of >2, and that the resulting separation distributions can be statistically completely different in initially substructured clusters. We also find that the mass ratio distributions are altered (destroying more low mass ratio systems), but not as significantly as the binary fractions or separation distributi...

  2. Observational Evidence for Tidal Interaction in Close Binary Systems

    CERN Document Server

    Mazeh, Tsevi

    2008-01-01

    This paper reviews the rich corpus of observational evidence for tidal effects in short-period binaries. We review the evidence for ellipsoidal variability and for the observational manifestation of apsidal motion in eclipsing binaries. Among the long-term effects, circularization was studied the most, and a transition period between circular and eccentric orbits has been derived for eight coeval samples of binaries. As binaries are supposed to reach synchronization before circularization, one can expect finding eccentric binaries in pseudo-synchronization state, the evidence for which is reviewed. The paper reviews the Rossiter-McLaughlin effect and its potential to study spin-orbit alignment. We discuss the tidal interaction in close binaries that are orbited by a third distant companion, and review the effect of pumping the binary eccentricity by the third star. We then discuss the idea that the tidal interaction induced by the eccentricity modulation can shrink the binary separation. The paper discusses t...

  3. Evolution of Binary Stars in Multiple-Population Globular Clusters

    CERN Document Server

    Hong, Jongsuk; Sollima, Antonio; McMillan, Stephen L W; D'Antona, Franca; D'Ercole, Annibale

    2015-01-01

    The discovery of multiple stellar populations in globular clusters has implications for all the aspects of the study of these stellar systems. In this paper, by means of N-body simulations, we study the evolution of binary stars in multiple-population clusters and explore the implications of the initial differences in the spatial distribution of different stellar populations for the evolution and survival of their binary stars. Our simulations show that initial differences between the spatial distribution of first-generation (FG) and second-generation (SG) stars can leave a fingerprint in the current properties of the binary population. SG binaries are disrupted more efficiently than those of the FG population resulting in a global SG binary fraction smaller than that of the FG. As for surviving binaries, dynamical evolution produces a difference between the SG and the FG binary binding energy distribution with the SG population characterized by a larger fraction of high binding energy (more bound) binaries. ...

  4. On the dynamical evolution and end states of binary centaurs

    Science.gov (United States)

    Brunini, A.

    2014-01-01

    In this paper, we perform a numerical integration of 666 fictitious binary Centaurs coming from the trans Neptunian space. Our population is restricted to tight binaries whose components have sizes between 30 and 100 km. We included the dynamical perturbations from the giant planets, Kozai Cycles induced by the Sun and tidal friction on the orbits of the binaries. We found that most binaries are disrupted during one of the close planetary encounters, making the mean lifetime of binary Centaurs much shorter than the one of single Centaurs. Nearly 10 per cent of the binaries reach a very tight circular orbit, arguing in favour of the existence of a non-negligible population of contact Centaurs. Another 10 per cent survive as a binary during their lifetime as Centaur. Our simulations favour the existence of a small population of very tight binary Centaurs.

  5. Model-independent inference on compact-binary observations

    CERN Document Server

    Mandel, Ilya; Colonna, Andrea; Stevenson, Simon; Tiňo, Peter; Veitch, John

    2016-01-01

    The recent advanced LIGO detections of gravitational waves from merging binary black holes enhance the prospect of exploring binary evolution via gravitational-wave observations of a population of compact-object binaries. In the face of uncertainty about binary formation models, model-independent inference provides an appealing alternative to comparisons between observed and modelled populations. We describe a procedure for clustering in the multi-dimensional parameter space of observations that are subject to significant measurement errors. We apply this procedure to a mock data set of population-synthesis predictions for the masses of merging compact binaries convolved with realistic measurement uncertainties, and demonstrate that we can accurately distinguish subpopulations of binary neutron stars, binary black holes, and mixed black hole -- neutron star binaries.

  6. Model-independent inference on compact-binary observations

    OpenAIRE

    Mandel, Ilya; Farr, Will M.; Colonna, Andrea; Stevenson, Simon; Tiňo, Peter; Veitch, John

    2016-01-01

    The recent advanced LIGO detections of gravitational waves from merging binary black holes enhance the prospect of exploring binary evolution via gravitational-wave observations of a population of compact-object binaries. In the face of uncertainty about binary formation models, model-independent inference provides an appealing alternative to comparisons between observed and modelled populations. We describe a procedure for clustering in the multi-dimensional parameter space of observations t...

  7. The cool surfaces of binary near-Earth asteroids

    OpenAIRE

    Delbo, Marco; Walsh, Kevin; Mueller, Michael; Harris, Alan W.; Howell, Ellen S.

    2011-01-01

    Abstract Here we show results from thermal-infrared observations of km-sized binary Near-Earth Asteroids (NEAs). We combine previously published thermal properties for NEAs with newly derived values for three binary NEAs. The ?value derived from the Near-Earth Asteroid Thermal Model (NEATM) for each object is then used to estimate an average thermal inertia for the population of binary NEAs and compared against similar estimates for the population of non-binaries. We find that thes...

  8. Formation and evolution of X-ray binaries

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We review recent progress in theoretical understanding of X-ray binaries,which has largely been driven by new observations.We select several topics including formation of compact low-mass X-ray binaries,the evolutionary connection between low-mass X-ray binaries and binary and millisecond radio pulsars,and ultraluminous X-ray sources,to illustrate the interplay between theories and observations.

  9. Beyond-Binary Arithmetic: Algorithms and VLSI Implementations

    OpenAIRE

    Aoki, Takafumi; Higuchi, Tatsuo

    2000-01-01

    Beyond-binary arithmetic algorithms are defined as a new class of computer arithmetic algorithms which employ non-binary data representations to achieve higher performances beyond those of conventional binary algorithms. This paper presents prominent examples of beyond-binary arithmetic algorithms: examples include (i) a high-radix redundant division algorithm without using lookup tables, (ii) a high-radix redundant CORDIC algorithm for fast vector rotation, and (iii) redundant complex arithm...

  10. Predicting Social Trust with Binary Logistic Regression

    Science.gov (United States)

    Adwere-Boamah, Joseph; Hufstedler, Shirley

    2015-01-01

    This study used binary logistic regression to predict social trust with five demographic variables from a national sample of adult individuals who participated in The General Social Survey (GSS) in 2012. The five predictor variables were respondents' highest degree earned, race, sex, general happiness and the importance of personally assisting…

  11. The Benchmark Eclipsing Binary V530 Ori

    DEFF Research Database (Denmark)

    Torres, Guillermo; Lacy, Claud H. Sandberg; Pavlovski, Kresimir

    2015-01-01

    We report accurate measurements of the physical properties (mass, radius, temperature) of components of the G+M eclipsing binary V530 On. The M-type secondary shows a larger radius and a cooler temperature than predicted by standard stellar evolution models, as has been found for many other low...

  12. Testing the Binary Trigger Hypothesis in FUors

    CERN Document Server

    Green, Joel D; Rizzuto, Aaron C; Ireland, Michael J; Dupuy, Trent J; Mann, Andrew W; Kuruwita, Rajika

    2016-01-01

    We present observations of three FU Orionis objects (hereafter, FUors) with nonredundant aperture-mask interferometry (NRM) at 1.59 um and 2.12 um that probe for binary companions on the scale of the protoplanetary disk that feeds their accretion outbursts. We do not identify any companions to V1515 Cyg or HBC 722, but we do resolve a close binary companion to V1057 Cyg that is at the diffraction limit (rho = 58.3 +/- 1.4 mas or 30 +/- 5 AU) and currently much fainter than the outbursting star (delta(K') = 3.34 +/- 0.10 mag). Given the flux excess of the outbursting star, we estimate that the mass of the companion (M ~ 0.25 Msun) is similar to or slightly below that of the FUor itself, and therefore it resembles a typical T Tauri binary system. Our observations only achieve contrast limits of delta(K') ~ 4 mag, and hence we are only sensitive to companions that were near or above the pre-outburst luminosity of the FUors. It remains plausible that FUor outbursts could be tied to the presence of a close binary ...

  13. Spectropolarimetry of single and binary stars

    CERN Document Server

    Harries, T J

    2004-01-01

    Spectropolarimetry is a photon-hungry technique that will reach fruition in the 8-m telescope age. Here I summarize some of the stellar spectropolarimetric research that my collaborators and I have undertaken, with particular emphasis on the circumstellar environment of massive stars, symbiotic binaries, and star formation.

  14. Binaries are the best single stars

    NARCIS (Netherlands)

    de Mink, S.E.; Langer, N.; Izzard, R.G.

    2010-01-01

    Stellar models of massive single stars are still plagued by major uncertainties. Testing and calibrating against observations is essential for their reliability. For this purpose one preferably uses observed stars that have never experienced strong binary interaction, i.e. “true single stars”. Howev

  15. Cassini states for black-hole binaries

    CERN Document Server

    Correia, Alexandre C M

    2016-01-01

    Cassini states correspond to equilibria of the spin axis of a celestial body when its orbit is perturbed. They were initially described for planetary satellites, but the spin axes of black-hole binaries also present this kind of equilibria. In previous works, Cassini states were reported as spin-orbit resonances, but actually the spin of black-hole binaries is in circulation and there is no resonant motion. Here we provide a general description of the spin dynamics of black-hole binary systems based on a Hamiltonian formalism. In absence of dissipation the problem is integrable and it is easy to identify all possible trajectories for the spin for a given value of the total angular momentum. As the system collapses due to radiation reaction, the Cassini states are shifted to different positions, which modifies the dynamics around them. This is why the final spin distribution may differ from the initial one. Our method provides a simple way of predicting the distribution of the spin of black-hole binaries at th...

  16. Bloch-Zener oscillations in binary superlattices.

    Science.gov (United States)

    Dreisow, F; Szameit, A; Heinrich, M; Pertsch, T; Nolte, S; Tünnermann, A; Longhi, S

    2009-02-20

    Bloch-Zener oscillations, i.e., the coherent superposition of Bloch oscillations and Zener tunneling between minibands of a binary lattice, are experimentally demonstrated for light waves in curved femtosecond laser-written waveguide arrays. Visualization of double-periodicity breathing and oscillation modes is reported, and synchronous tunneling leading to wave reconstruction is demonstrated.

  17. Testing the Binary Trigger Hypothesis in FUors

    Science.gov (United States)

    Green, Joel D.; Kraus, Adam L.; Rizzuto, Aaron C.; Ireland, Michael J.; Dupuy, Trent J.; Mann, Andrew W.; Kuruwita, Rajika

    2016-10-01

    We present observations of three FU Orionis objects (hereafter, FUors) with nonredundant aperture-mask interferometry at 1.59 μm and 2.12 μm that probe for binary companions on the scale of the protoplanetary disk that feeds their accretion outbursts. We do not identify any companions to V1515 Cyg or HBC 722, but we do resolve a close binary companion to V1057 Cyg that is at the diffraction limit (ρ =58.3+/- 1.4 mas or 30 ± 5 au) and currently much fainter than the outbursting star ({{Δ }}K\\prime =3.34+/- 0.10 mag). Given the flux excess of the outbursting star, we estimate that the mass of the companion (M∼ 0.25{M}ȯ ) is similar to or slightly below that of the FUor itself, and therefore it resembles a typical T Tauri binary system. Our observations only achieve contrast limits of {{Δ }}K\\prime ∼ 4 mag, and hence we are only sensitive to companions that were near or above the pre-outburst luminosity of the FUors. It remains plausible that FUor outbursts could be tied to the presence of a close binary companion. However, we argue from the system geometry and mass reservoir considerations that these outbursts are not directly tied to the orbital period (i.e., occurring at periastron passage), but instead must only occur infrequently.

  18. Flip-flopping binary black holes.

    Science.gov (United States)

    Lousto, Carlos O; Healy, James

    2015-04-10

    We study binary spinning black holes to display the long term individual spin dynamics. We perform a full numerical simulation starting at an initial proper separation of d≈25M between equal mass holes and evolve them down to merger for nearly 48 orbits, 3 precession cycles, and half of a flip-flop cycle. The simulation lasts for t=20 000M and displays a total change in the orientation of the spin of one of the black holes from an initial alignment with the orbital angular momentum to a complete antialignment after half of a flip-flop cycle. We compare this evolution with an integration of the 3.5 post-Newtonian equations of motion and spin evolution to show that this process continuously flip flops the spin during the lifetime of the binary until merger. We also provide lower order analytic expressions for the maximum flip-flop angle and frequency. We discuss the effects this dynamics may have on spin growth in accreting binaries and on the observational consequences for galactic and supermassive binary black holes.

  19. Binaries are the best single stars

    CERN Document Server

    de Mink, S E; Izzard, R G

    2010-01-01

    Stellar models of massive single stars are still plagued by major uncertainties. Testing and calibrating against observations is essential for their reliability. For this purpose one preferably uses observed stars that have never experienced strong binary interaction, i.e. "true single stars". However, the binary fraction among massive stars is high and identifying "true single stars" is not straight forward. Binary interaction affects systems in such a way that the initially less massive star becomes, or appears to be, single. For example, mass transfer results in a widening of the orbit and a decrease of the luminosity of the donor star, which makes it very hard to detect. After a merger or disruption of the system by the supernova explosion, no companion will be present. The only unambiguous identification of "true single stars" is possible in detached binaries, which contain two main-sequence stars. For these systems we can exclude the occurrence of mass transfer since their birth. A further advantage is ...

  20. Binary pulsars as dark-matter probes

    CERN Document Server

    Pani, Paolo

    2015-01-01

    During the motion of a binary pulsar around the galactic center, the pulsar and its companion experience a wind of dark-matter particles that can affect the orbital motion through dynamical friction. We show that this effect produces a characteristic seasonal modulation of the orbit and causes a secular change of the orbital period whose magnitude can be well within the astonishing precision of various binary-pulsar observations. Our analysis is valid for binary systems with orbital period longer than a day. By comparing this effect with pulsar-timing measurements, it is possible to derive model-independent upper bounds on the dark-matter density at different distances $D$ from the galactic center. For example, the precision timing of J1713+0747 imposes $\\rho_{\\rm DM}\\lesssim 10^5\\,{\\rm GeV/cm}^3$ at $D\\approx7\\,{\\rm kpc}$. The detection of a binary pulsar at $D\\lesssim 10\\,{\\rm pc}$ could provide stringent constraints on dark-matter halo profiles and on growth models of the central black hole. The Square Kil...

  1. LSM is not generated by binary functions

    CERN Document Server

    McQuillan, Colin

    2011-01-01

    Bulatov et al. [1] defined the operation of (efficient) pps_\\omega-definability in order to study the computational complexity of certain approximate counting problems. They asked whether all log-supermodular functions can be defined by binary implication and unary functions in this sense. We give a negative answer to this question.

  2. Binary Solid-Liquid Phase Equilibria

    Science.gov (United States)

    Ellison, Herbert R.

    1978-01-01

    Indicates some of the information that may be obtained from a binary solid-liquid phase equilibria experiment and a method to write a computer program that will plot an ideal phase diagram to which the experimental results may be compared. (Author/CP)

  3. The Orbital Decay of Embedded Binary Stars

    CERN Document Server

    Stahler, Steven W

    2009-01-01

    Young binaries within dense molecular clouds are subject to dynamical friction from ambient gas. Consequently, their orbits decay, with both the separation and period decreasing in time. A simple analytic expression is derived for this braking torque. The derivation utilizes the fact that each binary acts as a quadrupolar source of acoustic waves. The acoustic disturbance has the morphology of a two-armed spiral and carries off angular momentum. From the expression for the braking torque, the binary orbital evolution is also determined analytically. This type of merger may help explain the origin of high-mass stars. If infrared dark clouds, with peak densities up to 10^7 cm^{-3}, contain low-mass binaries, those with separations less than 100 AU merge within about 10^5 yr. During the last few thousand years of the process, the rate of mechanical energy deposition in the gas exceeds the stars' radiative luminosity. Successive mergers may lead to the massive star formation believed to occur in these clouds.

  4. Binary translation using peephole translation rules

    Science.gov (United States)

    Bansal, Sorav; Aiken, Alex

    2010-05-04

    An efficient binary translator uses peephole translation rules to directly translate executable code from one instruction set to another. In a preferred embodiment, the translation rules are generated using superoptimization techniques that enable the translator to automatically learn translation rules for translating code from the source to target instruction set architecture.

  5. Orbits of Ten Visual Binary Stars

    Institute of Scientific and Technical Information of China (English)

    B.Novakovi(c)

    2007-01-01

    We present the orbits of ten visual binary stars:WDS 01015+6922.WDS 01424-0645,WDS 01461+6349,WDS 04374-0951,WDS 04478+5318,WDS 05255-0033,WDS 05491+6248,WDS 06404+4058,WDS 07479-1212,and WDS 18384+0850.We have also determined their masses,dynamical parallaxes and ephemerides.

  6. Chandra Imaging of Gamma-Ray Binaries

    CERN Document Server

    Kargaltsev, Oleg; Hare, Jeremy; Pavlov, George G

    2013-01-01

    We review the multiwavelength properties of the few known gamma-ray binaries, focusing on extended emission recently resolved with Chandra. We discuss the implications of these findings for the nature of compact objects and for physical processes operating in these systems.

  7. DARPA/TTO program IR binary optics

    Science.gov (United States)

    Veldkamp, W. B.

    1984-06-01

    Binary grating optics consist of microfine rectangular (high-low) relief patterns on a dielectric or a metallic surface. By controlling the depth, width and periodicity of the binary pattern, the amplitude and the phase of an electromagnetic wave can be controlled to produce a variety of optical transfer functions. The lithographic tools for fabrication of binary optics are the ones developed for VLSI circuit fabrication. From a single lithographic mask, planar replica optics can be made in quantity. This technology has broad applicability for tactical missile systems as well as for space systems. In addition to making optics cheaper than by conventional means, binary optics allows the fabrication of unique devices that cannot be made conventionally. These include high-speed rotary scanners, multiplexers, filters, beam shapers and coherent laser adders. The goal of this program is the development of high quality planar optical components using VLSI circuit fabrication techniques. The main elements of the plan are: (1) the development of large aperture segmented and piezoelectrically active planar optical surfaces, (2) the development of raster scanning laser telescopes and extension to broadband applications, and (3) the application of diffractive optics technology to the coherent addition of beams from modular laser systems. This report covers progress in the setup of a reactive ion-beam etching laboratory, and the feasibility demonstrations of the coherent beam addition concept with gas lasers.

  8. Runaway Massive Binaries and Cluster Ejection Scenarios

    CERN Document Server

    McSwain, M V; Boyajian, T S; Grundstrom, E D; Roberts, M S E; Ransom, Scott M.; Boyajian, Tabetha S.; Grundstrom, Erika D.

    2006-01-01

    The production of runaway massive binaries offers key insights into the evolution of close binary stars and open clusters. The stars HD 14633 and HD 15137 are rare examples of such runaway systems, and in this work we investigate the mechanism by which they were ejected from their parent open cluster, NGC 654. We discuss observational characteristics that can be used to distinguish supernova ejected systems from those ejected by dynamical interactions, and we present the results of a new radio pulsar search of these systems as well as estimates of their predicted X-ray flux assuming that each binary contains a compact object. Since neither pulsars nor X-ray emission are observed in these systems, we cannot conclude that these binaries contain compact companions. We also consider whether they may have been ejected by dynamical interactions in the dense environment where they formed, and our simulations of four-body interactions suggest that a dynamical origin is possible but unlikely. We recommend further X-ra...

  9. ANGULAR-MOMENTUM IN BINARY SPIRAL GALAXIES

    NARCIS (Netherlands)

    OOSTERLOO, T

    1993-01-01

    In order to investigate the relative orientations of spiral galaxies in pairs, the distribution of the angle between the spin-vectors for a new sample of 40 binary spiral galaxies is determined. From this distribution it is found, contrary to an earlier result obtained by Helou (1984), that there is

  10. Binary Quadratic Forms: A Historical View

    Science.gov (United States)

    Khosravani, Azar N.; Beintema, Mark B.

    2006-01-01

    We present an expository account of the development of the theory of binary quadratic forms. Beginning with the formulation and proof of the Two-Square Theorem, we show how the study of forms of the type x[squared] + ny[squared] led to the discovery of the Quadratic Reciprocity Law, and how this theorem, along with the concept of reduction relates…

  11. Wobbling Ancient Binaries - Here Be Planets?

    CERN Document Server

    Horner, Jonathan; Hinse, Tobias; Marshall, Jonathan; Mustill, Alex

    2014-01-01

    In the last few years, a number of planets have been proposed to orbit several post main-sequence binary star systems on the basis of observed variations in the timing of eclipses between the binary components. A common feature of these planet candidates is that the best-fit orbits are often highly eccentric, such that the multiple planet systems proposed regularly feature mutually crossing orbits - a scenario that almost always leads to unstable planetary systems. In this work, we present the results of dynamical studies of all multiple-planet systems proposed to orbit these highly evolved binary stars, finding that most do not stand up to dynamical scrutiny. In one of the potentially stable cases (the NN Serpentis 2-planet system), we consider the evolution of the binary star system, and show that it is highly unlikely that planets could survive from the main sequence to obtain their current orbits - again casting doubt on the proposed planets. We conclude by considering alternative explanations for the obs...

  12. Chemically homogeneous evolution in massive binaries

    CERN Document Server

    de Mink, S E; Langer, N; Pols, O R

    2010-01-01

    Rotation can have severe consequences for the evolution of massive stars. It is now considered as one of the main parameters, alongside mass and metallicity that determine the final fate of single stars. In massive, fast rotating stars mixing processes induced by rotation may be so efficient that helium produced in the center is mixed throughout the envelope. Such stars evolve almost chemically homogeneously. At low metallicity they remain blue and compact, while they gradually evolve into Wolf-Rayet stars and possibly into progenitors of long gamma-ray bursts. In binaries this type of evolution may occur because of (I) tides in very close binaries, as a result of (II) spin up by mass transfer, as result of (III) a merger of the two stars and (IV) when one of the components in the binary was born with a very high initial rotation rate. As these stars stay compact, the evolutionary channels are very different from what classical binary evolutionary models predict. In this contribution we discuss examples of ne...

  13. Echoes in X-ray Binaries

    CERN Document Server

    O'Brien, K; Hynes, R; Chen, W; Haswell, C; Still, M

    2002-01-01

    We present a method of analysing the correlated X-ray and optical/UV variability in X-ray binaries, using the observed time delays between the X-ray driving lightcurves and their reprocessed optical echoes. This allows us to determine the distribution of reprocessing sites within the binary. We model the time-delay transfer functions by simulating the distribution of reprocessing regions, using geometrical and binary parameters. We construct best-fit time-delay transfer functions, showing the regions in the binary responsible for the reprocessing of X-rays. We have applied this model to observations of the Soft X-ray Transient, GRO j1655-40. We find the optical variability lags the X-ray variability with a mean time delay of 19.3$pm{2.2}$ seconds. This means that the outer regions of the accretion disc are the dominant reprocessing site in this system. On fitting the data to a simple geometric model, we derive a best-fit disk half-opening angle of 13.5$^{+2.1}_{-2.8}$ degrees, which is similar to that observe...

  14. The Primordial Binary Population in OB Associations

    NARCIS (Netherlands)

    Kouwenhoven, M.B.N.; Brown, A.G.A.; Gualandris, A.; Kaper, L.; Portegies Zwart, S.F.; Zinnecker, H.; Allen, C.; Scarfe, C.

    2004-01-01

    We present the first results of our adaptive optics survey of 200 (mainly) A-type stars in the nearby OB association Sco OB2, which we will use, together with literature data and detailed simulations of young star clusters, to determine the primordial binary population.

  15. What's Next? Judging Sequences of Binary Events

    Science.gov (United States)

    Oskarsson, An T.; Van Boven, Leaf; McClelland, Gary H.; Hastie, Reid

    2009-01-01

    The authors review research on judgments of random and nonrandom sequences involving binary events with a focus on studies documenting gambler's fallacy and hot hand beliefs. The domains of judgment include random devices, births, lotteries, sports performances, stock prices, and others. After discussing existing theories of sequence judgments,…

  16. Planet formation in slightly inclined binary systems

    Directory of Open Access Journals (Sweden)

    Ge J.

    2011-07-01

    Full Text Available One of the major problems of planet formation in close binary systems, such as α Centauri AB, is the formation of planetary embryos or cores by mutual accretion of km-sized planetesimals. In this contribution, we test the planetesimal accretion in such close binary systems but with small inclinations iB = 0.1–10° between the binary orbital plane and the gas disk plane. Compared to previous studies (coplanar case with iB = 0, we find that (1 planetesimal disk is stratified in the vertical direction and planetesimals are redistributed on different orbit groups with respect to their sizes, thus (2 collisions between similar-sized bodies dominate, leading to low dV and favoring planetesimal accretion (3 the planetesimal collision timescale at 1–2 AU is estimated as: T ∼ (1 + 100iB × 103 yrs, where 0 ≤ iB ≤ 10°. As a conclusion, although planetesimal accretion are much more favored in slightly inclined binary systems, it is significantly less efficient and slowed-down as compared to the single-star case.

  17. Balanced binary trees in the Tamari lattice

    CERN Document Server

    Giraudo, Samuele

    2010-01-01

    We show that the set of balanced binary trees is closed by interval in the Tamari lattice. We establish that the intervals [T0, T1] where T0 and T1 are balanced trees are isomorphic as posets to a hypercube. We introduce tree patterns and synchronous grammars to get a functional equation of the generating series enumerating balanced tree intervals.

  18. Parameter estimation of gravitational wave compact binary coalescences

    Science.gov (United States)

    Haster, Carl-Johan; LIGO Scientific Collaboration Collaboration

    2017-01-01

    The first detections of gravitational waves from coalescing binary black holes have allowed unprecedented inference on the astrophysical parameters of such binaries. Given recent updates in detector capabilities, gravitational wave model templates and data analysis techniques, in this talk I will describe the prospects of parameter estimation of compact binary coalescences during the second observation run of the LIGO-Virgo collaboration.

  19. Binary interaction dominates the evolution of massive stars

    NARCIS (Netherlands)

    Sana, H.; de Mink, S.E.; de Koter, A.; Langer, N.; Evans, C.J.; Gieles, M.; Gosset, E.; Izzard, R.G.; Le Bouquin, J.-B.; Schneider, F.R.N.

    2012-01-01

    The presence of a nearby companion alters the evolution of massive stars in binary systems, leading to phenomena such as stellar mergers, x-ray binaries, and gamma-ray bursts. Unambiguous constraints on the fraction of massive stars affected by binary interaction were lacking. We simultaneously meas

  20. The Formation of Contact and Very Close Binaries

    Energy Technology Data Exchange (ETDEWEB)

    Kisseleva-Eggleton, L; Eggleton, P P

    2007-08-10

    We explore the possibility that all close binaries, i.e. those with periods {approx}< 3 d, including contact (W UMa) binaries, are produced from initially wider binaries (periods of say 10's of days) by the action of a triple companion through the medium of Kozai Cycles with Tidal Friction (KCTF).

  1. Microlensing Binaries Discovered through High-magnification Channel

    DEFF Research Database (Denmark)

    Shin, I.-G.; Choi, J.-Y.; Park, S.-Y.

    2012-01-01

    Microlensing can provide a useful tool to probe binary distributions down to low-mass limits of binary companions. In this paper, we analyze the light curves of eight binary-lensing events detected through the channel of high-magnification events during the seasons from 2007 to 2010. The perturba...

  2. A decoding method of an n length binary BCH code through (n + 1n length binary cyclic code

    Directory of Open Access Journals (Sweden)

    TARIQ SHAH

    2013-09-01

    Full Text Available For a given binary BCH code Cn of length n = 2 s - 1 generated by a polynomial of degree r there is no binary BCH code of length (n + 1n generated by a generalized polynomial of degree 2r. However, it does exist a binary cyclic code C (n+1n of length (n + 1n such that the binary BCH code Cn is embedded in C (n+1n . Accordingly a high code rate is attained through a binary cyclic code C (n+1n for a binary BCH code Cn . Furthermore, an algorithm proposed facilitates in a decoding of a binary BCH code Cn through the decoding of a binary cyclic code C (n+1n , while the codes Cn and C (n+1n have the same minimum hamming distance.

  3. Kepler Eclipsing Binary Stars. VIII. Identification of False Positive Eclipsing Binaries and Re-extraction of New Light Curves

    CERN Document Server

    Abdul-Masih, Michael; Conroy, Kyle; Bloemen, Steven; Boyajian, Tabetha; Doyle, Laurance R; Johnston, Cole; Kostov, Veselin; Latham, David W; Matijevic, Gal; Shporer, Avi; Southworth, John

    2016-01-01

    The Kepler Mission has provided unprecedented, nearly continuous photometric data of $\\sim$200,000 objects in the $\\sim$105 deg$^{2}$ field of view from the beginning of science operations in May of 2009 until the loss of the second reaction wheel in May of 2013. The Kepler Eclipsing Binary Catalog contains information including but not limited to ephemerides, stellar parameters and analytical approximation fits for every known eclipsing binary system in the Kepler Field of View. Using Target Pixel level data collected from Kepler in conjunction with the Kepler Eclipsing Binary Catalog, we identify false positives among eclipsing binaries, i.e. targets that are not eclipsing binaries themselves, but are instead contaminated by eclipsing binary sources nearby on the sky and show eclipsing binary signatures in their light curves. We present methods for identifying these false positives and for extracting new light curves for the true source of the observed binary signal. For each source, we extract three separa...

  4. Merging Galaxies Create a Binary Quasar

    Science.gov (United States)

    2010-02-01

    Astronomers have found the first clear evidence of a binary quasar within a pair of actively merging galaxies. Quasars are the extremely bright centers of galaxies surrounding super-massive black holes, and binary quasars are pairs of quasars bound together by gravity. Binary quasars, like other quasars, are thought to be the product of galaxy mergers. Until now, however, binary quasars have not been seen in galaxies that are unambiguously in the act of merging. But images of a new binary quasar from the Carnegie Institution's Magellan telescope in Chile show two distinct galaxies with "tails" produced by tidal forces from their mutual gravitational attraction. "This is really the first case in which you see two separate galaxies, both with quasars, that are clearly interacting," says Carnegie astronomer John Mulchaey who made observations crucial to understanding the galaxy merger. Most, if not all, large galaxies, such as our galaxy the Milky Way, host super-massive black holes at their centers. Because galaxies regularly interact and merge, astronomers have assumed that binary super-massive black holes have been common in the Universe, especially during its early history. Black holes can only be detected as quasars when they are actively accreting matter, a process that releases vast amounts of energy. A leading theory is that galaxy mergers trigger accretion, creating quasars in both galaxies. Because most such mergers would have happened in the distant past, binary quasars and their associated galaxies are very far away and therefore difficult for most telescopes to resolve. The binary quasar, labeled SDSS J1254+0846, was initially detected by the Sloan Digital Sky Survey, a large scale astronomical survey of galaxies and over 120,000 quasars. Further observations by Paul Green of the Harvard-Smithsonian Center for Astrophysics and colleagues* using NASA's Chandra's X-ray Observatory and telescopes at Kitt Peak National Observatory in Arizona and Palomar

  5. Cognitive Binary Logic - The Natural Unified Formal Theory of Propositional Binary Logic

    CERN Document Server

    Popescu-Bodorin, Nicolaie

    2011-01-01

    This paper presents a formal theory which describes propositional binary logic as a semantically closed formal language, and allows for syntactically and semantically well-formed formulae, formal proofs (demonstrability in Hilbertian acception), deduction (Gentzen's view of demonstrability), CNF-ization, and deconstruction to be expressed and tested in the same (computational) formal language, using the same data structure. It is also shown here that Cognitive Binary Logic is a self-described theory in which the Liar Paradox is deconstructed.

  6. Binary-disk interaction. II. Gap-opening criteria for unequal-mass binaries

    Energy Technology Data Exchange (ETDEWEB)

    Del Valle, Luciano; Escala, Andrés, E-mail: ldelvalleb@gmail.com [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile)

    2014-01-01

    We study the interaction of an unequal-mass binary with an isothermal circumbinary disk, motivated by the theoretical and observational evidence that after a major merger of gas-rich galaxies, a massive gaseous disk with a supermassive black hole binary will be formed in the nuclear region. We focus on the gravitational torques that the binary exerts on the disk and how these torques can drive the formation of a gap in the disk. This exchange of angular momentum between the binary and the disk is mainly driven by the gravitational interaction between the binary and a strong nonaxisymmetric density perturbation that is produced in the disk, in response to the presence of the binary. Using smoothed particle hydrodynamics numerical simulations, we test two gap-opening criteria, one that assumes the geometry of the density perturbation is an ellipsoid/thick spiral and another that assumes a flat spiral geometry for the density perturbation. We find that the flat spiral gap-opening criterion successfully predicts which simulations will have a gap in the disk and which will not. We also study the limiting cases predicted by the gap-opening criteria. Since the viscosity in our simulations is considerably smaller than the expected value in the nuclear regions of gas-rich merging galaxies, we conclude that in such environments the formation of a circumbinary gap is unlikely.

  7. The Tarantula Massive Binary Monitoring: I. Observational campaign and OB-type spectroscopic binaries

    CERN Document Server

    Almeida, L A; Taylor, W; Barbá, R; Bonanos, A; Crowther, P; Damineli, A; de Koter, A; de Mink, S E; Evans, C J; Gieles, M; Grin, N J; Hénault-Brunet, V; Langer, N; Lennon, D; Lockwood, S; Apellániz, J Maíz; Moffat, A F J; Neijssel, C; Norman, C; Ramírez-Agudelo, O H; Richardson, N D; Schootemeijer, A; Shenar, T; Soszyński, I; Tramper, F; Vink, J S

    2016-01-01

    Massive binaries (MBs) play a crucial role in the Universe and knowing the distributions of their orbital parameters (OPs) is important for a wide range of topics, from stellar feedback to binary evolution channels, from the distribution of supernova types to gravitational wave progenitors. Yet, no direct measurements exist outside the Milky Way. The Tarantula Massive Binary Monitoring was designed to help fill this gap by obtaining multi-epoch radial velocity monitoring of 102 MBs in the 30 Dor. In this paper, we analyse 32 FLAMES/GIRAFFE observations of 93 O- and 7 B-type binaries. We performed a Fourier analysis and obtained orbital solutions for 82 systems: 51 single-lined and 31 double-lined spectroscopic binaries. Overall, the OPs and binary fraction are remarkably similar across the 30 Dor region and compared to existing Galactic samples (GSs). This indicates that within these domains environmental effects are of second order in shaping the properties of MBs. A small difference is found in the distribu...

  8. Binary Disk interaction II: Gap-Opening criteria for unequal mass binaries

    CERN Document Server

    del Valle, Luciano

    2013-01-01

    We study the interaction between an unequal mass binary with an isothermal circumbinary disk, motivated by the theoretical and observational evidence that after a major merger of gas-rich galaxies, a massive gaseous disk with a SMBH binary will be formed in the nuclear region. We focus on the gravitational torques that the binary exerts onto the disk and how these torques can drive the formation of a gap in the disk. This exchange of angular momentum between the binary and the disk is mainly driven by the gravitational interaction between the binary and a strong non-axisymmetric density perturbation that is produced in the disk, as response to the presence of the binary. Using SPH numerical simulations we tested two gap-opening criterion, one that assumes that the geometry of the density perturbation is an ellipsoid/thick-spirals and another that assumes a geometry of flat-spirals for the density perturbation. We find that the flat-spirals gap opening criterion successfully predicts which simulations will hav...

  9. Disc-Jet Coupling in the Terzan 5 Neutron Star X-ray Binary EXO 1745$-$248

    CERN Document Server

    Tetarenko, A J; Sivakoff, G R; Tremou, E; Linares, M; Tudor, V; Miller-Jones, J C A; Heinke, C O; Chomiuk, L; Strader, J; Altamirano, D; Degenaar, N; Maccarone, T; Patruno, A; Sanna, A; Wijnands, R

    2016-01-01

    We present the results of VLA, ATCA, and Swift XRT observations of the 2015 outburst of the transient neutron star X-ray binary (NSXB), EXO 1745$-$248, located in the globular cluster Terzan 5. Combining (near-) simultaneous radio and X-ray measurements we measure a correlation between the radio and X-ray luminosities of $L_R\\propto L_X^\\beta$ with $\\beta=1.68^{+0.10}_{-0.09}$, linking the accretion flow (probed by X-ray luminosity) and the compact jet (probed by radio luminosity). While such a relationship has been studied in multiple black hole X-ray binaries (BHXBs), this work marks only the third NSXB with such a measurement. Constraints on this relationship in NSXBs are strongly needed, as comparing this correlation between different classes of XB systems is key in understanding the properties that affect the jet production process in accreting objects. Our best fit disc-jet coupling index for EXO 1745$-$248 is consistent with the measured correlation in NSXB 4U 1728$-$34 ($\\beta=1.5\\pm 0.2$) but inconsi...

  10. THE ELM SURVEY. V. MERGING MASSIVE WHITE DWARF BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Warren R.; Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA 02138 (United States); Kilic, Mukremin; Gianninas, A. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK, 73019 (United States); Allende Prieto, Carlos, E-mail: wbrown@cfa.harvard.edu, E-mail: skenyon@cfa.harvard.edu, E-mail: kilic@ou.edu, E-mail: alexg@nhn.ou.edu, E-mail: callende@iac.es [Instituto de Astrofisica de Canarias, E-38205, La Laguna, Tenerife (Spain)

    2013-05-20

    We present the discovery of 17 low-mass white dwarfs (WDs) in short-period (P {<=} 1 day) binaries. Our sample includes four objects with remarkable log g {approx_equal} 5 surface gravities and orbital solutions that require them to be double degenerate binaries. All of the lowest surface gravity WDs have metal lines in their spectra implying long gravitational settling times or ongoing accretion. Notably, six of the WDs in our sample have binary merger times <10 Gyr. Four have {approx}>0.9 M{sub Sun} companions. If the companions are massive WDs, these four binaries will evolve into stable mass transfer AM CVn systems and possibly explode as underluminous supernovae. If the companions are neutron stars, then these may be millisecond pulsar binaries. These discoveries increase the number of detached, double degenerate binaries in the ELM Survey to 54; 31 of these binaries will merge within a Hubble time.

  11. Binary interaction dominates the evolution of massive stars

    CERN Document Server

    Sana, H; de Koter, A; Langer, N; Evans, C J; Gieles, M; Gosset, E; Izzard, R G; Bouquin, J -B Le; Schneider, F R N; 10.1126/science.1223344

    2012-01-01

    The presence of a nearby companion alters the evolution of massive stars in binary systems, leading to phenomena such as stellar mergers, X-ray binaries and gamma-ray bursts. Unambiguous constraints on the fraction of massive stars affected by binary interaction were lacking. We simultaneously measured all relevant binary characteristics in a sample of Galactic massive O stars and quantified the frequency and nature of binary interactions. Over seventy per cent of all massive stars will exchange mass with a companion, leading to a binary merger in one third of the cases. These numbers greatly exceed previous estimates and imply that binary interaction dominates the evolution of massive stars, with implications for populations of massive stars and their supernovae.

  12. 1974: the discovery of the first binary pulsar

    CERN Document Server

    Damour, Thibault

    2014-01-01

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

  13. Twin Binaries: Studies of Stability, Mass Transfer, and Coalescence

    CERN Document Server

    Lombardi, James C; Dooley, Katherine L; Gearity, Kyle; Kalogera, Vassiliki; Rasio, Frederic A

    2010-01-01

    Motivated by suggestions that binaries with almost equal-mass components ("twins") play an important role in the formation of double neutron stars and may be rather abundant among binaries, we study the stability of synchronized close and contact binaries with identical components in circular orbits. In particular, we investigate the dependency of the innermost stable circular orbit on the core mass, and we study the coalescence of the binary that occurs at smaller separations. For twin binaries composed of convective main-sequence stars, subgiants, or giants with low mass cores (M_c ~0.15M), we find that stable contact configurations exist at all separations down to the Roche limit, when mass shedding through the outer Lagrangian points triggers a coalescence of the envelopes and leaves the cores orbiting in a central tight binary. We discuss the implications of our results to the formation of binary neutron stars.

  14. The state of globular clusters at birth - II. Primordial binaries

    Science.gov (United States)

    Leigh, Nathan W. C.; Giersz, Mirek; Marks, Michael; Webb, Jeremy J.; Hypki, Arkadiusz; Heinke, Craig O.; Kroupa, Pavel; Sills, Alison

    2015-01-01

    In this paper, we constrain the properties of primordial binary populations in Galactic globular clusters. Using the MOCCA Monte Carlo code for cluster evolution, our simulations cover three decades in present-day total cluster mass. Our results are compared to the observations of Milone et al. using the photometric binary populations as proxies for the true underlying distributions, in order to test the hypothesis that the data are consistent with a universal initial binary fraction near unity and the binary orbital parameter distributions of Kroupa. With the exception of a few possible outliers, we find that the data are to first-order consistent with the universality hypothesis. Specifically, the present-day binary fractions inside the half-mass radius can be reproduced assuming either high initial binary fractions near unity with a dominant soft binary component as in the Kroupa distribution combined with high initial densities (104-106 M⊙ pc-3), or low initial binary fractions (˜5-10 per cent) with a dominant hard binary component combined with moderate initial densities near their present-day values (102-103 M⊙ pc-3). This apparent degeneracy can potentially be broken using the binary fractions outside the half-mass radius - only high initial binary fractions with a significant soft component combined with high initial densities can reproduce the observed anticorrelation between the binary fractions outside the half-mass radius and the total cluster mass. We further illustrate using the simulated present-day binary orbital parameter distributions and the technique first introduced in Leigh et al. that the relative fractions of hard and soft binaries can be used to further constrain both the initial cluster density and the initial mass-density relation. Our results favour an initial mass-density relation of the form r_h ∝ M_clus^{α } with α < 1/3, corresponding to an initial correlation between cluster mass and density.

  15. Coalescence of Magnetized Binary Neutron Star Systems

    Science.gov (United States)

    Motl, Patrick M.; Anderson, Matthew; Lehner, Luis; Liebling, Steven L.; Neilsen, David; Palenzuela, Carlos; Ponce, Marcelo

    2015-01-01

    We present simulations of the merger of binary neutron star systems calculated with full general relativity and incorporating the global magnetic field structure for the stars evolved with resistive magnetohydrodynamics. Our simulation tools have recently been improved to incorporate the effects of neutrino cooling and have been generalized to allow for tabular equations of state to describe the degenerate matter. Of particular interest are possible electromagnetic counterparts to the gravitational radiation that emerges from these systems. We focus on magnetospheric interactions that ultimately tap into the gravitational potential energy of the binary to power a Poynting flux and deposition of energy through Joule heating and magnetic reconnection. We gratefully acknowledge the support of NASA through the Astrophysics Theory Program grant NNX13AH01G.

  16. A Binary Representation of the Genetic Code

    CERN Document Server

    Nemzer, Louis R

    2016-01-01

    This article introduces a novel binary representation of the canonical genetic code, in which each of the four mRNA nucleotide bases is assigned a unique 2-bit identifier. These designations have a physiological meaning derived from the molecular structures of, and relationships between, the bases. In this scheme, the 64 possible triplet codons are each indexed by a 6-bit label. The order of the bits reflects the hierarchical organization manifested by the DNA replication/repair and tRNA translation systems. Transition and transversion mutations are naturally expressed as basic binary operations, and the severity of the different types is analyzed. Using a principal component analysis, it is shown that physicochemical properties of amino acids related to protein folding also correlate with particular bit positions of their respective labels. Thus, the likelihood for a particular point mutation to be conservative, and therefore less likely to cause a change in protein functionality, can be estimated.

  17. Simulation of nuclei morphologies for binary alloy

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We study the critical nuclei morphologies of a binary alloy by the string method. The dynamic equation of the string, connecting the metastable phase (liquid) and stable phase (solid), is governed by Helmholtz free energy for the binary alloy system at a given temperature. The stationary string through the critical nucleus (saddle point) is obtained if the relaxation time of the string is su?ciently large. The critical nucleus radius and energy barrier to nucleation of a pure alloy with isotropic interface energy in two and three dimensions are calculated, which are consistent with the classical nucleation theory. The critical nuclei morphologies are sensitive to the anisotropy strength of interface energy and interface thickness of alloy in two and three dimensions. The critical nucleus and energy barrier to nucleation become smaller if the anisotropy strength of the interface energy is increased, which means that it is much easier to form a stable nucleus if the anisotropy of the interface energy is considered.

  18. Binary Fingerprints at Fluctuation-Enhanced Sensing

    CERN Document Server

    Chang, Hung-Chih; King, Maria D; Kwan, Chiman

    2009-01-01

    We developed a simple way to generate binary patterns based on spectral slopes in different frequency ranges at fluctuation-enhanced sensing. Such patterns can be considered as binary "fingerprints" of odors. The method has experimentally been demonstrated with a commercial semiconducting metal oxide (Taguchi) sensor exposed to bacterial odors (Escherichia coli and Anthrax-surrogate Bacillus subtilis) and processing their stochastic signals. With a single Taguchi sensor, the situations of empty chamber, tryptic soy agar (TSA) medium, or TSA with bacteria could be distinguished with 100% reproducibility. The bacterium numbers were in the range of 25 thousands to 1 million. To illustrate the relevance for ultra-low power consumption, we show that this new type of signal processing and pattern recognition task can be implemented by a simple analog circuitry and a few logic gates with total power consumption in the microWatts range.

  19. Particle algorithms for optimization on binary spaces

    CERN Document Server

    Schäfer, Christian

    2011-01-01

    We propose a general sequential Monte Carlo approach for optimization of pseudo-Boolean objective functions. There are three aspects we particularly address in this work. First, we give a unified approach to stochastic optimization based on sequential Monte Carlo techniques, including the cross-entropy method and simulated annealing as special cases. Secondly, we point out the need for auxiliary sampling distributions, that is parametric families on binary spaces, which are able to reproduce complex dependency structures. We discuss some known and novel binary parametric families and illustrate their usefulness in our numerical experiments. Finally, we provide numerical evidence that particle-driven optimization algorithms yield superior results on strongly multimodal optimization problems while local search heuristics outperform them on easier problems.

  20. BINARY NONLINEARIZATION FOR THE DIRAC SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    MAWENXIU

    1997-01-01

    A Bargmann symmetry constraint is proposed for the Lax pairs and the adjoint Lax pairs of the Dirac systems. It is shown that the spatial part of the nonlinearized Lax pairs and adjoint Lax pairs is a finite dimensional Linuville integrable Hamiltonian system and that under the control of the spatial part, the time parts of the nonlinearized Lax pairs and adjoint Lax pairs are interpreted as a hierarchy of commutative, finite dimensional Linuville integrable Hamiltoian systems whose Hamiltonian functions consist of a series of integrals of motion for the spatial part. Moreover an invaiutive representation of solutions of the Dirac systems exhibits their integrability by quadratures. This kind of symmetry constraint procedure involving thespectral problem and the adjoint spectral problem is referred to as a binary nonlinearization technique like a binary Darhoux transformation.