XTE(ASM) and BATSE links to Accreting Pulsars. Last Updated: December 6, 2002 ... Undetermined Companion, Anomalous X-ray Pulsars (non-accretion objects) ...
NASA Website
accreting pulsar systems. These have given new insights into the processes by ... Observations of transient pulsars with BATSE and OSSE have provided ...
The formation of millisecond pulsars is addressed. Evolutionary scenarios involving the spinning up of pulsars by accretion disks are discussed, and the implications of the P(dot)-P diagram for a large sample of radio pulsars are examined. 13 references.
Energy Citations Database
Jul 2, 2003 ... Caption for Animation 1: ACCRETION SPINS PULSAR TO MILLISECOND RANGE. If a pulsar -- a dense star with strong gravitational attraction -- is ...
Neutron Stars, Pulsars, Millisecond Pulsars, and Gravitational Radiation: GLOSSARY. Accretion disk: The flattened, pancake-like structure formed by matter ...
Therefore it is commonly referred to as "the Bursting Pulsar". The X-rays observed by RXTE come from accretion onto a pulsar with a spin period of 0.467 s ...
The nature of pulsars that exhibit quasi-periodic oscillations (QPOs) is discussed. It is shown how QPOs are produced by an interaction between the accretion disk surrounding a neutron star with the neutron star's magnetic field. The possible relationship between pulsars that exhibit QPOs and millisecond ...
Isolated (solitary or non-accreting) millisecond pulsars with observed X-ray emission can be divided
NASA Technical Reports Server (NTRS)
The 2002 outburst of the accretionpowered millisecond pulsar SAX J1808.43658. Askar Ibragimov and prof. Juri Poutanen. University of Oulu, Finland ...
... Hamilton 2001; Hansen 2002), but all generally rely on an accretion disk around the pulsar within which the planets form. Millisecond pulsars are a ...
DTIC Science & Technology
The Cygnus X-3 source might represent a long-period accreting pulsar, a companion to a red supergiant in a binary system with an orbital period of several years.
We review recent results from the X-ray timing of accreting millisecond pulsars in LMXBs. This is the first time a timing analysis is performed on accreting millisecond pulsars, and for the first time we can obtain information on the behavior of a very fast pulsar subject to ...
NASA Astrophysics Data System (ADS)
We have detected highly significant X-ray pulsations in a series of pointings with the Rossi X-ray Timing Explorer Proportional Counter Array at the putative pulsar/PWN IGR J18490-0000 = HESS J1849-000 = XMMU J184901.6-000117 (Terrier et al. 2008, AIPC, 1085, 312). The single-peaked pulse profile has a modulation of 4.5% including background.
been considered a critical test of accretion torque theory (x 3). We have observed _ and 20{50keV pulsed. ux, F pulsed , in outbursts of two transients, ...
The accreting pulsar GX 301-2 (P = 680 s) has been observed continuously by the large-area detectors
The time variability of the x ray binary pulsars is discussed. It is found that the observed power spectral density of the aperiodic time variability of the x ray pulsar can be approximated by a power law spectrum which changes its slope at the coherent p...
National Technical Information Service (NTIS)
Pulsar spindown forms a reliable yet enigmatic prototype for the energy loss processes in many astrophysical objects including accretion disks and back holes. In this paper we review the physics of pulsar magnetospheres, concentrating on recent developmen...
Aims: One of the goals of the XMM-Newton survey of the Small Magellanic Cloud is to study the Be/X-ray binary population. During one of our first survey observations, a bright new transient - XMMU J004814.0-732204 - was discovered. Methods: We present the analysis of the EPIC X-ray data, together with optical observations, to investigate the spectral and temporal ...
This presentation describes the behavior of matter in environments with extreme magnetic and gravitational fields, explains the instability/stability of accretion disks in certain systems, and discusses how emergent radiation affects accretion flow. Magne...
Observations of millisecond pulsars are discussed, taking into account a review of millisecond pulsars, arrival time observations of the 1.6 millisecond pulsar 1937 + 214, a 6.1 millisecond binary pulsar, polarimetry of the two fastest pulsars, an optical synchrotron nebula around the X-ray ...
This paper discusses a search for the centrifugal barrier in transient X-ray pulsars with RXTE. The RXTE observation associated with this research involved monitoring the X-ray intensities and pulse profiles of six transient x-ray pulsars on five different occasions. The goal was to determine whether the so-called "centrifugal barrier" effects exists for ...
Pulsar spindown forms a reliable yet enigmatic prototype for the energy loss processes in many astrophysical objects including accretion disks and back holes. In this paper we review the physics of pulsar magnetospheres, concentrating on recent developments in force-free modeling of the magnetospheric structure. In particular, we ...
Millisecond pulsars are believed to descend from low-mass X-ray binaries. Observable parameters of binary millisecond pulsars, e.g. mass of the pulsar, mass of the companion, spin period of the pulsar, orbital period, orbital eccentricity, etc., are used to probe the past accretion history of ...
Pulsars inside binary systems can accrete matter that arrives up to the pulsar surface provided that its period is long enough. During the accretion process, matter has to be accelerated to the rotational velocity of the pulsar magnetosphere at the distance where the balance between the ...
I review the basic observational properties of accreting millisecond pulsars that are important for understanding the physics involved in formation of their pulse profiles. I then discuss main effects responsible for shaping these profiles. Some analytical results that help to understand the results of simulations are presented. Constraints on the ...
We investigate further a model of the accreting millisecond X-ray pulsars we proposed earlier. In this model, the X-ray-emitting regions of these pulsars are near their spin axes but move. This is to be expected if the magnetic poles of these stars are close to their spin axes, so that accreting gas is channeled ...
The discovery of a new transient X-ray pulsar, EXO 2030+375, that is associated with a Be star companion, is reported. The results of a series of EXOSAT observations, where the evolution of the pulsar's properties over two orders of magnitude in luminosity was monitored. The dependence of the change in pulsar period on ...
Millisecond pulsars, both during and after accretion, stand a class apart from the general pulsar population due to the much weaker field strength at their surface. The prevailing view is that accretion of matter on to a neutron star causes a decay of its magnetic field strength, as viewed by an external observer. ...
Topics covered include young rapidly spinning pulsars; static gaps in outer magnetospheres; dynamic gaps in pulsar outer magnetospheres; pulse structure of energetic radiation sustained by outer gap pair production; outer gap radiation, Crab pulsar; outer gap radiation, the Vela pulsar; radioemission; and high ...
DOE Information Bridge
The maximum acceleration of the rotation of an accreting star is found. A comparison with observations of x-ray pulsars shows that they are neutron stars but not white dwarfs. It is found that the experimentally determined rates of deceleration of x-ray pulsars correlate with their luminosities and periods. This indicates that x-ray ...
Context. The transient X-ray source XMMU J004215.8+411924 within M 31 was found to be in outburst again in the 2010 May 27 Chandra observation. We present results from our four Chandra and seven Swift observations that covered this outburst. Aims: X-ray transient behaviour is generally caused by one of two things: mass accretion from a high mass companion ...
A neutron star in a binary system whose other component is a Wolf--Rayet star will undergo distinctive accretion. In such a system an x-ray pulsar could develop only under highly special conditions.
Mar 25, 1998 ... This one of 12 known transient accreting X-ray pulsars with no visible companion . Pulsars - rotating neutron stars - are among the most ...
Oct 25, 2005 ... GOF, RXTE Finds the First Millisecond Pulsar in an Accreting X-ray ... the times at which the signals from the pulsar arrival at the Earth. ...
An analytic model of magnetic torques applied to an accreting neutron star is employed to evaluate the magnetic dipole moments of x-ray pulsars. A new type of close binary system containing a neutron star is suggested.
In contrast with bipolar jets from the magnetic rotating bodies with accretion flows, it is expected for pulsar winds that high energy outflow is in a ring-like shape. It is also suggested that the kinetic energy flux is comparable with the Poynting flux.
By careful measurements of the fluctuations in pulsar pulse periods on time scales of days and longer, researchers determined that these fluctuations are caused by changes in the rotation rate of the stellar crust apparently arising from matter accretion....
Dec 15, 2009 ... detected with the GBM pulsar monitoring technique ..... Accreting Pulsars with GBM Earth Occultation. Vela X-1. GX301-2. A0535+26. A0535+262 ...
A unified description of the properties of 14 X-ray pulsars is presented and compared with the current theoretical understanding of these systems. The sample extends over six orders of magnitude in luminosity, with the only trend in the phase averaged spe...
Relativistic one and two photon Compton scattering in a strong magnetic field was calculated. X-ray pulsar model calculations are presented for the phase-dependent spectrum, pulse shape, cyclotron line profile, degree and angle of linear polarization for ...
Dramatic torque reversals between spin-up and spin-down have been observed in half of the persistent
Over 5 years of daily hard X-ray (>20 keV) monitoring of the 2 minute accretion-powered pulsar GX
The discovery of orbitally-modulated, periodic X-ray pulsations from Cen ...... Ariel 5 discovered 103 s pulsations from A 0535+26 in 1975 (Rosenberg et al. ...
Accreting high magnetic field neutron stars are observed as X-ray pulsars. ... An examination of a power spectrum of the pulsed emission shows that the peak ...
Aug 17, 2010... in the universe and test a key prediction of Einstein's relativity theory. ... "Like many accreting binary systems, J1749 undergoes outbursts ...
In the course of the XMM-Newton survey of the Small Magellanic Cloud, a region to the east of the emission nebula N19 was observed in 2009 November. To search for new candidates for high-mass X-ray binaries, the EPIC-pn and EPIC-MOS data of the detected point sources were investigated and their spectral and temporal characteristics identified. A new transient (XMMU ...
ries containing weakly magnetized neutron stars, and to recently suggested models of accretion-powered emission from anomalous X-ray pulsars. ...
We review recent results of our group on X-ray timing of accreting millisecond pulsars in LMXBs. The good quality of the RXTE data allow us to obtain information on the behavior of a very fast pulsar subject to accretion torques. We find both spin-up and spin-down behaviors, from which, using available models for ...
After more than 40 years of studies, surprisingly little is known on the emission of accreting pulsars at low-luminosity. It was suggested that already at 10^{35} ergs/s the onset of a centrifugal barrier should inhibit the accretion. On the other hand, pulsations during quiescence were reported for three transient ...
The exchange of angular momentum between accreting matter and the magnetosphere of a neutron star is studied as a possible explanation for the soft X-ray emission of X-ray pulsars. The flux of soft X-radiation from Her X-1 may be related to dissipation of rotational energy of accreting matter into a layer of the disk at the radial ...
The broadened iron lines observed from accreting compact objects are most easily interpreted in terms of reflection onto the accretion disc of the hard X-ray photons emitted by the central source. In this context, such a broadness is due to the relativistic motion of the reflecting plasma, in the deep gravitational well of the compact object, and can thus ...
Very recently the discovery of an intermittent radio pulsar was reported on Science (Kramer et al.2006,astro-ph/0604605). PSR B1931+24 has the surprising peculiarity of being a 813ms radio-pulsar for ~5d and being radio quiet for the following 25-35d, periodically. The pulsar spin slows down 50% faster when the ...
The present conference considers topics in the fields of rotation-powered pulsars, the relationship of pulsars to SNRs, accretion-powered pulsars, neutron-star formation in theoretical SNs, neutrol stellar evolution, neutron star physics, and other manifestations of neutron stars and their place in neutron star ...
The influence of the hot spot that very likely forms at the base of the accretion column of X-ray pulsars with X-ray luminosities not much larger than ?1030W onto emitted spectra and angle dependent fluxes is discussed.
It is now more than eleven years since the discovery of the first accreting millisecond X-ray pulsar. Since then, eleven additional systems have been found, two of them during the last year. Here I briefly discuss the most recent developments with respect to these systems.
Based on XMM-Newton EPIC data of four pointings towards the Small Magellanic Cloud (SMC), results on timing and spectral analyses of 16 known high mass X-ray binaries (HMXBs) and HMXB candidates in the SMC are presented. We confirm the pulse periods of four sources which were known to show pulsations. In addition, two new X-ray pulsars are discovered: XMMU ...
During the period 15 April 1997 through 15 April 2000 we have been supported in part by NASA grant NAG5-4115 to pursue a 'Search for the Centrifugal Barrier in Transient X-ray Pulsars' with the Rossi X-Ray Timing Explorer (RXTE). The RXTE observations associated with this research involved monitoring the X-ray intensities and pulse profiles of six transient X-ray ...
that this is already greater than one Earth mass, this may mean that isolated millisecond pulsars either have planetary MILLISECOND PULSARS M. COLEMAN MILLER AND DOUGLAS P. HAMILTON Department of Astronomy, University of Maryland the millisecond pulsar PSR 1257]12. We show that recent developments in the study of ...
E-print Network
We present an evolutionary scenario for the spin-up and evolution of binary millisecond pulsars, according to which the companion of the pulsar PSR J1740-5340 , recently discovered as a binary with orbital period of 32.5 hrs in the Globular Cluster NGC 6397, is presently in a phase of `radio--ejection' mass loss from the system.
A Sequence of Outbursts from the Transient X�Ray Pulsar GS 0834--430 Colleen A. Wilson, Mark H accretion�powered pulsar, has been observed in seven outbursts with the BATSE large area detectors on the Compton Gamma Ray Observatory. The first 5 outbursts observed by BATSE occurred at intervals of about 107
In the absence of accretion torques, a pulsar in a binary system will spin down due to electromagnetic dipole radiation and the spin-down power will drive a wind of relativistic electron-positron pairs. Winds from pulsars with short periods will prevent any subsequent accretion but may be confined by the companion ...
In the absence of accretion torques, a pulsar in a binary system will spin down due to electromagnetic dipole radiation, and the spin-down power will drive a wind of relativistic electron-position pairs. Winds from pulsars with short periods will prevent any subsequent accretion but may be confined by the companion ...
We report on the Swift detection of a thermonuclear X-ray burst from the very-faint quasi-persistent neutron star X-ray binary XMMU J174716.1-281048, which triggered the satellite's Burst Alert Telescope (BAT) on 2010 August 13. Analysis of the BAT spectrum yields an observed bolometric peak flux of ?4.5 � 10-8 erg cm-2 s-1, from which we infer a source distance of ?8.4 kpc. ...
We study accretion-induced collapse of magnetized white dwarfs as an origin of millisecond pulsars. We apply magnetized accretion disk models to the precollapse accreting magnetic white dwarfs and calculate the white dwarf spin evolution. If the pulsar magnetic field results solely from the ...
We report here a study of the long term properties of Quasi Periodic Oscillations (QPO) in an unusual accreting X-ray pulsar, 4U 1626-67. This is a unique accretion powered X-ray pulsar in which we have found the QPOs to be present during all sufficiently long X-ray observations with a wide range of X-ray ...
We report here a study of the long-term properties of quasiperiodic oscillations (QPOs) in an unusual accreting X-ray pulsar, 4U 1626-67. This is a unique accretion-powered X-ray pulsar in which we have found the QPOs to be present during all sufficiently long X-ray observations with a wide range of X-ray ...
Recent work suggests that rotating magnetized neutron stars (i.e., pulsar models) trap plasma instead of emitting it. The trapping arises because nonneutral plasma can be stably trapped within such a magnetosphere provided the overall system charge is nonzero. It has been argued that particles from the interstellar medium would discharge this system, thereby presumably ...
It has been clear for many years now that the process of accretion on to a compact object is largely dominated by magnetic fields. The magnetic field channels the accretion flow onto strongly magnetized stars such as magnetic white dwarfs (cataclysmic variables), and neutron stars (accreting X-ray pulsars). ...
RXTE observations have shown that weak-field neutron stars in low-mass X-ray binary systems (LMXBs) produce three distinct types of millisecond X-ray oscillations. These are generated directly or indirectly by the star's magnetic field and rotation and can therefore be used to determine the spin rates and estimate the magnetic fields of these stars. Periodic accretion-powered ...
The accreting millisecond pulsar SAX J1808.4-3658 may be a transition object between accreting X-ray binaries and millisecond radio pulsars. We have constrained the thermal radiation from its surface through XMM-Newton X-ray observations, providing strong evidence for neutrino cooling processes from the neutron ...
We present a theoretical model for the thermal X-ray emission properties and cooling behaviors of isolated pulsars, assuming that pulsars are solid quark stars. We calculate the heat capacity for such a quark star, including the component of the crystalline lattice and that of the extremely relativistic electron gas. The results show that the residual ...
CONSTRAINTS ON ACCRETION AND MAGNETAR MODELS D. L. KAPLAN,1 S. R. KULKARNI,1 M. H. VAN KERKWIJK,2 R. E strong new constraints on both accretion disk and magnetar models and suggest that the spectral energy, and a magnetar would require a D1015�1016 G �eld. Subject headings : accretion, accretion disks � ...
An initial study of the evolution of a neutron star in a close-binary orbit of high eccentricity discloses a special class of systems that will never achieve a state of pure, steady accretion: the neutron star will continually oscillate between an accreting state and a propeller state. This may be what is happening in the rapid-spin ...
Rotation-powered radio pulsars are born with inferred initial rotation periods of order 300 ms (some as short as 20 ms) in core-collapse supernovae. In the traditional picture, this fast rotation is the result of conservation of angular momentum during the collapse of a rotating stellar core. This leads to the inevitable conclusion that pulsar spin is ...
PubMed
Jan 21, 1998 ... Other stars like Cen X-3 - accreting pulsars - have been acting strangely, too. The spin rate for 4U 1626-67 was increasing smoothly, ...
Jul 15, 2004 ... "X-Ray Bursts from the Accreting Millisecond Pulsar XTE J1814-338", ... ``Bounds on Compactness for LMXB Neutron Stars from X-ray Burst ...
drift is apparent in the Short High pulses showing that a re ned period can be ... Figure 5 shows a sequence of Uhuru pulses from 3] from a single Main High ...
The BATSE all-sky monitor on the Compton Gamma Ray Observatory is a superb tool for the study of accretion-powered pulsars. In the #rst part of this thesis, I describe its capabilities for hard X-ray observations above20keV, present techniques for timing analysis of the BATSE data, and discuss general statistical issues for the detection of pulsed periodic ...
@clarence.gsfc.nasa.gov, craigm@milkyway. gsfc.nasa.gov. 483 The Astrophysical Journal, 619: 483�491, 2005 January 20 # 2005
The Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO) monitored the entire sky from 1991-2000. I will review highlights of BATSE observations including gamma ray bursts, black hole candidates, accreting pulsar...
We present the results of a targeted search for radio pulsars in globular clusters, supernova remnants (SNRs) and transient X-ray sources. 85 globular clusters, 29 SNRs and three transient X-ray sources were observed in the course of the search, during which four pulsars were found. For each object searched, the sensitivity limit is given. The four new ...
We report the optical detection of a faint star consistent with the known position of the 401 Hz transient accreting millisecond X-ray pulsar IGR J17498-2921 (ATel #3551, #3555, #3556, #3558, #3559, #3560, #3561, #3562, #3563, #3568, #3601, #3606). On 2011-08-25 and 2011-08-26 (MJD 55798.4 - 55799.5) we observed the field of IGR J17498-2921 with the 2-m ...
We report the discovery of burst oscillations from the intermittent accretion-powered millisecond pulsar (AMP) HETE J1900.1-2455, with a frequency ~1 Hz below the known spin frequency. The burst oscillation properties are far more similar to those of the non-AMPs and Aql X-1 (an intermittent AMP with a far lower duty cycle), than those of the AMPs SAX ...
The recycling model suggested that low-mass X-ray binaries (LMXBs) could evolve into binary millisecond pulsars (BMSPs). In this work, we attempt to investigate the progenitor properties of BMSPs formed by the recycling evolutionary channel, and if submillisecond pulsars can be produced by this channel. Using Eggleton's stellar evolution code, considering ...
We report on a Chandra Director's Discretionary Time observation of the globular cluster Terzan 5, carried out �7 weeks after the cessation of the 2010 outburst of the newly discovered transiently accreting 11-Hz X-ray pulsar. We detect a thermal spectrum that can be fitted with a neutron star atmosphere model with a temperature for an observer at ...
X-ray timing of the accretion-powered pulsations during the 2003 outburst of the accreting millisecond pulsar XTE J1814-338 has revealed variation in the pulse time of arrival residuals. These can be interpreted in several ways, including spin-down and wandering of the fuel impact point around the magnetic pole. In this Letter we show ...
GS 0834-430, a 12.3 s accretion-powered pulsar, has been observed in seven outbursts with the BATSE large-area detectors on the Compton Gamma Ray Observatory. The first five outbursts observed by BATSE occurred at intervals of about 107 days, while the fi...
This volume presents 41 articles by distinguished Chinese and Western scientists on topics such as pulsars, neutron stars, supernova explosions, neutrino processes, cataclysmic binaries and other phenomena. As a record of progress in the field, this book is an indispensable guide and reference for professionals and students in astrophysics. Topics considered include ...
Accreting millisecond X-ray pulsars like IGR J00291+5934 are important because they can be used to test theories of pulsar formation and evolution. They give also the possibility of constraining gravitational wave emission theories and the equation of state of ultra-dense matter. Particularly crucial to our understanding is the ...
Pulsar astrophysics has come a long way in the 40 years since the discovery of the first pulsar by Bell and Hewish. From humble beginnings as bits of 'scruff' on the Cambridge University group's chart recorder paper, the field of pulsars has blossomed into a major area of mainstream astrophysics, with an unparalleled diversity of ...
This thesis consists of two parts. In the first hart, we present the development of instruments for high-speed infrared and optical photometry optimized for pulsar observations. In the second part, we present observational studies of pulsars, mainly on accretion- powered pulsars but also on rotation-powered ...
Chandra ACIS observed the field of the extended TeV source HESS J1834-087 for 47 ks. A previous XMM-Newton EPIC observation of the same field revealed a point-like source (XMMU J183435.3-084443) and an offset region of faint extended emission. In the low-resolution, binned EPIC images the two appear to be connected. However, the high-resolution Chandra ACIS images do not ...
In binary systems containing an X-ray pulsar, the X-ray flux shows aperiodic noise components in addition to the neutron star rotation signal. In the power spectra of their light curves, the noise variability appears in the form of continuum components underlying the discrete peaks arising from the coherent periodic signals. The study of these continuum components can add to ...
The heating associated with the deposition of ?-rays in an accretion disk is proposed as a mechanism to facilitate the transformation of a low-mass X-ray binary to the radio millisecond pulsar (MSP) phase. The ?-ray emission produced in the outer gap accelerator in the pulsar magnetosphere likely irradiates the surrounding disk, ...
In millisecond pulsars the existence of the Coriolis force allows the development of the so-called Rossby oscillations (r-modes) which are know to be unstable to emission of gravitational waves. These instabilities are mainly damped by the viscosity of the star or by the existence of a strong magnetic field. A fraction of the observed millisecond pulsars ...
Using three-dimensional hydrodynamics simulations, we have identified a robust instability of the stalled accretion shock in core-collapse supernovae that is able to generate a strong rotational flow in the vicinity of the accreting proto-neutron star (PNS). Sufficient angular momentum is deposited on the PNS to generate a final neutron star spin period ...
We present for the first time, the self-consistent solution of the two-dimensional, time-dependent equations of radiation-hydrodynamics governing the accretion of matter onto the highly magnetized polar caps of luminous x-ray pulsars. The calculations sho...
Bright pulsating X-ray sources (X-ray pulsars, AM Her stars,...) have been identified as strongly magnetized compact objects accreting matter from a binary companion. We give here a summary of some of the work which has been recently done to try to unders...
An optical, intensified CCD observation of the field of the 3.49 s X-ray pulsar lE 2259+586 is discussed. Two stars with B = 22.0 and B = 21.3 are found to lie 4.''9 and 6.''3 away from the nominal X-ray position determined by the High Resolution Imager (HRI) camera of the Einstein Observatory. The fainter star is identified as the optical ...
PSR J1744-3922 is a binary pulsar exhibiting highly variable pulsed radio emission. We report on a statistical multifrequency study of the pulsed radio flux variability which suggests that this phenomenon is extrinsic to the pulsar and possibly tied to the companion, although not strongly correlated with orbital phase. The pulsar has ...
Accreting millisecond pulsars show significant variability of their pulse profiles, especially at low accretion rates. On the other hand, their X-ray spectra are remarkably similar with not much variability over the course of the outbursts. For the first time, we have discovered that during the 2008 outburst of SAX J1808.4-3658 a major ...
The spin behaviour of a strongly magnetic star accreting from an internally disrupted disc is considered. The torques are calculated due to the interaction of the star with the disc and the accretion flow, together with the modified structure of the disc. The torques depend on the spin period of the star, and a stable equilibrium period can be found at ...
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 ...
This paper examines the deceleration of accreting material in the strongly magnetized plasma atmosphere of an X-ray pulsar, for accretion rates less than 0.1 times the Eddington flux. The previous work on accretion, flow deceleration is extended to nonisothermal atmospheres. A rough model of radiative processes in ...
We calculate the rapid proton ( rp) capture process of hydrogen burning on the surface of an accreting neutron star with an updated reaction network that extends up to Xe, far beyond previous work. In both steady-state nuclear burning appropriate for rapidly accreting neutron stars (such as the magnetic polar caps of accreting x-ray ...
Neutron stars in general have space velocities much higher than their progenitors. This is believed to be the result of momentum kicks imparted during core collapse. However, the nature of the kick remains an open question. Abetted by recent progress in measuring pulsar proper motions and spin orientations, it has become possible to make improved comparison between the ...
Phase transitions can be triggered by a change of density profile in neutron stars as a result of spin-up caused by mass accretion from a companion star. Such a spin evolution is the pathway from old canonical pulsars to millisecond pulsars. A number of x-ray neutron stars have been recently observed by the Rossi x-ray timing explorer ...
Nuclear-powered oscillations during Type-I X-ray bursts have so far revealed the spin of about twenty accreting millisecond pulsars in low-mass X-ray binaries. We study the properties of such burst oscillations by means of numerical computations of hot spots on the neutron star surface. We use adaptive mesh refinement hydrodynamical simulations to model ...
The self-consistency of the standard model for accreting X-ray pulsars is reexamined, using observational data on two X-ray sources, Her X-1 and 4U0115 + 63, interpreted in the context of the MHD accretion torque theory of Ghosh and Lamb (1979). Within a phenomenologically extended version of this theory, it is shown that the inner ...
Recent discovery of an unexpectedly large number of low-mass binary pulsars (LMBPs) in globular clusters has instigated active discussions on the evolutionary origin of binary pulsars. Prompted by the possibility that at least some of LMBPs originate from accretion-induced collapse (AIC) of white dwarfs, a reexamination is conducted as ...
UV emission in many X-ray binaries is dominated by X-raysreprocessed in the accretion disk. For pulsars illumination ofthe accretion disk by a rotating beam of X-rays should resultin pulsed UV emission lines with Doppler shifts correspondingto projected gas velocities. Simultaneous high time resolutionUV and X-ray spectra thus offer a ...
We report the optical discovery of the companion to the 2 M sun millisecond pulsar PSR J1614�2230. The optical colors show that the 0.5 M sun companion is a 2.2 Gyr old He-CO white dwarf. We infer that \\dot{M} during the accretion phase is {<}10^{-2}\\,\\dot{M}_edd. We show that the pulsar was born with a spin close to its ...
The spectrum of the X-ray binary pulsars is usually described by a power-law model, but several sources exhibit a significant excess at low energies. This feature has been described with different models (both thermal and non-thermal), and various physical processes have been invoked to produce it. The study of this feature is essential in order to cast light on the on-going ...
The population of radio pulsars in the Galactic globular cluster system has nearly quadrupled in the last five years largely due to advances in observing equipment and increased computational power There are currently 130 sources known many of which can be used to study the physics of neutron stars globular clusters binary systems accretion and the ...
LS I +61 303 is a puzzling Be/X-ray binary with variable gamma-ray emission at up TeV energies. The nature of the compact object and the origin of the high-energy emission are unclear. One family of models invokes particle acceleration in shocks from the collision between the B-star wind and a relativistic pulsar wind, while another centers on a relativistic jet powered by ...
We identify two candidate magnetars in archival X-ray observations of HESS-detected shell-type supernova remnants (SNRs). X-ray point sources in CTB 37B coincident with HESS J1713 - 381 and in G353.6 - 0.7 coincident with HESS J1731 - 347 both have anomalous X-ray pulsar (AXP) like spectra, much softer than those of ordinary, rotation-powered pulsars, and ...
The evolutionary scenario of neutron star binaries is still an essential enigma in both stellar astrophysics and high energy astrophysics. In order to explore the scenario, we include the accumulation of data on the orbits and spins of compact binaries in multi-wavelength ranging from radio to X-ray, such as radio pulsar binaries, HMXBs, and LMXBs, filling them into the so ...
We study the statistics of 61 measured masses of neutron stars (NSs) in binary pulsar systems, including 18 double NS (DNS) systems, 26 radio pulsars (10 in our Galaxy) with white dwarf (WD) companions, 3 NSs with main-sequence companions, 13 NSs in X-ray binaries, and one undetermined system. We derive a mean value of M = 1.46 � 0.30 M?. When the 46 NSs ...
Context. In addition to coherent pulsation, many accreting neutron stars exhibit flaring activity and strong aperiodic variability on time scales comparable to or shorter than their pulsation period. This behavior shows that the accretion flow in the vicinity of the accretor must be highly non-stationary. Observational study of this phenomenon is often ...
Millisecond pulsars are neutron stars that are thought to have been spun-up by mass accretion from a stellar companion. It is not known whether there is a natural brake for this process, or if it continues until the centrifugal breakup limit is reached at submillisecond periods. Many neutron stars that are accreting mass from a ...
In this paper we discuss the spin equilibrium of accreting neutron stars in low-mass X-ray binaries (LMXBs). We demonstrate that, when combined with a naive spin-up torque, the observed data lead to inferred magnetic fields which are at variance with those of Galactic millisecond radio pulsars. This indicates the need for either additional spin-down ...
Pulsars with pulsation periods in the millisecond range are thought to be neutron stars that have acquired an extraordinarily short spin period through the accretion of stellar material spiraling down onto the neutron star from a nearby companion. Nearly all the angular momentum and most of the mass of the companion star is transferred to the neutron star. ...
The illumination of companion stars in very low mass X-ray binaries by various kinds of radiation from the neighborhood of the neutron star after accretion has terminated or during accretion is considered. If a neutron star's spun-up period approaches 0.001 s, pulsar kHz radiation can quench accretion by ...
Accretion onto compact objects plays a central role in high energy astrophysics. In these environments, both general relativistic and plasma effects may have significant impacts upon the spectral and polarimetric properties of the accretion flow. In paper I we presented a fully general relativistic magnetoionic theory, capable of tracing rays in the ...
