XTE(ASM) and BATSE links to Accreting Pulsars. Last Updated: December 6, 2002 ... Undetermined Companion, Anomalous X-ray Pulsars (non-accretion objects) ...

Isolated (solitary or non-accreting) millisecond pulsars with observed X-ray emission can be divided

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...

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 ...

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...

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 ...

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 ...

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. ...

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 ...

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...

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 ...

We will describe a Thomson X-ray polarimeter developed for a small satellite mission. The instrument works in the 5-30 keV band and will be suitable for X-ray polarisation measurement in about 50 hard X-ray sources. The accretion powered X-ray pulsars, black hole X-ray ...

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.

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 ...

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 ...

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. ...

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

ries containing weakly magnetized neutron stars, and to recently suggested models of accretion-powered emission from anomalous X-ray pulsars. ...

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 ...

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 ...

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 ...

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 ...

The discovery of six X ray pulsars and several candidates of X ray pulsars is reported. These new pulsars and candidates show a high concentration towards the Scutum region. The pulse profiles, in several energy bands and X ...

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 ...

We analyzed seven, target ID 31686, Swift follow-up observations of the neutron-star X-ray transient Swfit J1749.4-2807 (Wijnands et al. 2009) currently in outburst and which was found to be an accreting millisecond X-ray pulsar (ATel #2565). The observations span from April 11 to April 20.

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 ...

Anomalous X-ray pulsars (AXPs) are a class of rare X-ray emitting pulsars whose energy source has been perplexing for some 20 years. Unlike other X-ray emitting pulsars, AXPs cannot be powered by rotational energy or by accretion of matter from a binary ...

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 ...

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...

... profile of the persistent (ie non-bursting) pulsar emission is fit ... X RAY SPECTROSCOPY, *HARD X RAYS, *PULSARS, OBSERVATION, RUPTURE ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

Progress made over the last decade in the understanding of the binary X-ray pulsars is reviewed. The

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 ...

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 ...

Dec 4, 2001 ... What is a Pulsar? What Makes a Pulsar Pulse? Gamma-Ray Pulsars ... Pulsars and the Formation of Neutron Stars; X-ray Observations of Pulsars ...

We present a detailed spectral and timing analysis of the High Mass X-ray Binary (HMXB) 4U 1909+07 with INTEGRAL and RXTE. 4U 1909+07 is a persistent accreting X-ray pulsar with a period of approximately 605 s. The period changes erratically consistent wi...

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 ...

The only known accretion-powered millisecond X-ray pulsar SAX J1808.4-3658 exhibited an outburst in January and Februay of this year. The exact starting date is unknown because the source was unobservable by RXTE until 2000 Jan. 21, due to its proximity to the sun. The 401 Hz X-ray pulsations were detected in ...

Re-analysis of a Swift/XRT ToO observation of IGR J01572-7259 in the Magellanic Bridge (=IGR J015712-7259, c.f. Coe et al., 2008, ATel #1882) has enabled us to establish the first soft X-ray spectrum for this 11.6-s X-ray pulsar and suspected high-mass X-ray binary. Observation-ID 00031313001 was taken on ...

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 ...

We report on pre-outburst optical (VRIHalpha) and near-infrared (NIR; JHKs) imaging observations of the field containing the newly discovered transient accreting milli-second X-ray pulsar IGR J17498-2921 (ATel #3551). The observations were done with the Mosaic (optical) and ISPI (NIR) cameras on the CTIO-4m Blanco telescope as part of ...

The region of sky containing the 38 s X-ray pulsar OAO 1657 - 415 has been observed on March 1990 with Sigma, an imaging gamma-ray telescope exploiting the coded mask technique. This observation has yielded an accurate (about arcminute-scale) localization for OAO 1657 - 415 at hard X-ray energy, confirming its association with a previously suggested soft ...

The Crab Nebula and pulsar constitute an intricate system, ... of the complex X- ray structure of the inner nebula and pulsar, ...

Gamma-ray loud X-ray binaries are binary systems that show non-thermal broadband emission from radio to gamma rays. If the system comprises a massive star and a young non-accreting pulsar, their winds will collide producing broadband non-thermal emission, most likely originated in the shocked pulsar wind. Thermal ...

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 ...

... Understanding of accretion disks, accretion flows, X-ray induced winds, compact obect evolution are all in a primitive state. ...

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...

We present Suzaku and XMM observations of the high-mass X-ray pulsar LMC X-4 at different phases in its superorbital cycle, which is due to the precession of a warped accretion disk. The superorbital period and phase for each observation is determined accurately using RXTE ASM data. At all superorbital phases, the broadband ...

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 ...

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 ...

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...

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 ...

Context. The burst-only source Swift J1749.4-2807 was discovered in a high X-ray-active state, during an INTEGRAL observations of the Galactic bulge on 2010 April 10. Pulsations at 518 Hz were discovered in the RXTE data, confirming previous suggestions of possible associations between burst-only sources and accreting millisecond X-ray ...

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 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 ...

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 ...

Here the reader will find a description of the current state of experimental and theoretical investigations of neutron stars in all their manifestations: radio pulsars, X-ray pulsars, X-ray bursters, transient X-ray sources, and so on. The approach adopted stresses the idea that the ...

I show that the assumption that the acceleration and collimation mechanisms of jets are the same in all the classes of astrophysical objects which are observed to produce jets, can lead to interesting conclusions. Jets have now been observed in: active galactic nuclei, young stellar objects, massive x-ray binaries, low mass x-ray binaries, black hole ...

Preliminary results of several programs to detect thermal X-ray emission from isolated neutron stars

The Energetic X-ray Imaging Survey Telescope (EXIST) is a proposed NASA mission for scanning the entire sky in intermediate and hard X-rays. The EXIST mission includes a wide field of view High Energy Telescope (HET) covering the 5-600 keV energy range, and an infrared telescope. The HET has the capability to measure the energy dependent ...

Context. It is commonly believed that millisecond radio pulsars have been spun up by transfer of matter and angular momentum from a low-mass companion during an X-ray active mass transfer phase. A subclass of low-mass X-ray binaries is that of the accreting millisecond X-ray pulsars, transient ...

We propose deep observations of the very early and late orbital phases of the archetypical wind accreting X-ray pulsar Vela X-1 including the egress and ingress of the X-ray source. These long observations will allow to track the many absorbing structures in the system in detail thus enhancing our knowledge about Vela X-1 and wind ...

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. Constraining strong gravity through the emission from the hot spots on the neutron star surface requires understanding of the properties of such burst ...

Results are presented of several Einstein and Exosat X-ray observations of 4U 1145 - 619, an X-ray pulsar orbiting the Be star HD 102567/Hen 715 with marked transient behavior. Pulse-timing analysis of data from imaging instruments on both missions was performed using a period-folding technique, which showed an interesting variation of the light curve ...

Several neutron stars associated with the accretion-powered long-period X-ray pulsars are observed to experience rapid spin-down years-long trends. Modeling of these trends in terms of the canonical spin-down scenario for accretionpowered compact stars in close binaries suggests that the surface field of these neutron stars is ...

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. ...

Radio pulsars with millisecond spin periods are thought to have been spun up by the transfer of matter and angular momentum from a low-mass companion star during an x-ray-emitting phase. The spin periods of the neutron stars in several such low-mass x-ray binary (LMXB) systems have been shown to be in the millisecond regime, but no radio pulsations have ...

Radio pulsars with millisecond spin periods are thought to have been spun up by the transfer of matter and angular momentum from a low-mass companion star during an x-ray-emitting phase. The spin periods of the neutron stars in several such low-mass x-ray binary (LMXB) systems have been shown to be in the millisecond regime, but no radio pulsations have ...

Thanks to its high throughput and good spatial, timing and spectral resolution, the XMM-Newton X-ray space telescope is well suited to perform detailed studies also of faint X-ray sources. Here we report the results we obtained on the persistent Be binaries, a sub-class of the accreting X-ray binary ...

We present here the high-resolution X-ray spectrum of the accreting binary X-ray pulsar GX 1+4, obtained with the High Energy Transmission Grating (HETG) instrument of the Chandra X-Ray Observatory. This was supplemented by a simultaneous observation with the Proportional Counter Array (PCA) of ...

The detection of soft X-rays of about 1 keV energy from the eclipsing pulsar PSR1957+20 is reported.

This grant, titled 'X-Ray Emission from Two Nearby Millisecond Pulsars,' included ROSAT observations

... Accession Number : ADA523788. Title : Spacecraft Navigation Using X-ray Pulsars. Descriptive Note : Journal article. Corporate ...

We find clear evidence for at least three cyclotron line features. ... quence, the X- ray spectra of pulsars may contain cyclotron resonance scattering features ...

the Earth. Only a small (~0.l m2) X-ray detector need be carried by the satellite. This is in sharp contrast to navigation using radio pulsars, which give ...

A class of low-mass X-ray binary sources are known to be both X-ray burst sources and millisecond pulsars at the same time. A new source of this class was discovered by High Energy Transient Explorer 2 (HETE-2) on 14 June 2005 as a source of type-I X-ray bursts, which was named HETE J1900.1-2455. Three (two ...

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 ...

The following topics were dealt with:- black hole thermodynamics, cosmology, Sunyaev-Zeldovich effect, Kaluza-Klein theories, Dirac equation in Kerr geometry, missing mass, compact object radiative outflows, neutron star accretion discs, astrophysical jets, nucleosynthesis around black holes, quasi-periodic oscillations, astronomical X-ray detectors, ...

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 ...

The PSR 1259--63 system is unique in that it is the first radio pulsar found to be in a binary system with a massive main sequence companion. As such, it may be the evolutionary missing link connecting the radio pulsars to the X-ray emitting Be binaries. In this paper, we consider the conditions under which PSR 1259-63 may be the progenitor of the less ...

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 ...

We observed the Geminga pulsar with the EUVE satellite, detecting pulsed emission in the Deep Survey

pulsars. Its October 2002 outburst is of particular interest because of the discovery of kilohertz quasi-periodic oscillations ...

Over the past decade our understanding of accreting neutron stars has been revolutionized. Observations with NASA's Rossi X-ray Timing Explorer (RXTE) have resulted in the discovery of fast, coherent X-ray intensity oscillations (hereafter, ``burst oscillations'') during thermonuclear X-ray bursts from 13 low mass ...

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 ...

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 ...

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 ...

The archetypical wind-accreting X-ray pulsar Vela X-1 is known to be variable on a large range of timescales. Relatively tranquil phases exist as well as extended phases of high variability and flaring. We present results from a systematic study of variations with orbital phase and other timescales based on RXTE/ASM and Swift/BAT data.

Ways of determining the nature of the companion to the pulsar PSR 1913+16 from observations of the pulsar's orbit and the slow rate of the orbit's precession are discussed. Geometric constraints require that the companion be a black hole, a neutron star, a white dwarf, or a helium-main sequence star. A uniform, geometrically thin slab was used to ...

We discuss the properties of HD49798/RXJ0648.0-4418 the only known X-ray binary composed by a hot sub-dwarf and an X-ray pulsar. We recently found evidence that the pulsations are due to a very massive (1.28 Msolar), fast rotating (13 s) white dwarf. The future evolution of this post common envelope binary will involve a new phase of mass ...

The magnetar model and a solid quark star model for anomalous X-ray pulsars/soft gamma-ray repeaters (AXPs/SGRs) are discussed. Different manifestations of pulsar-like stars are speculated to be due to both their nature (e.g., mass and strain) and their nurture (ambience, and consequently the type of accretion) in ...

The correlations between X-ray luminosity and pulse shape and spectral shape in selected X-ray pulsars are presented to check proposed trends which were noted with changing luminosity between differents pulsars. Individual pulsars at different luminosity ...

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 ...

We present an analysis of archival X-ray observations of the Type IIL supernova SN 1979C. We find that its X-ray luminosity is remarkably constant at (6.5 � 0.1) � 1038 erg s-1 over a period of 12 years between 1995 and 2007. The high and steady luminosity is considered as possible evidence for a stellar-mass (�5-10 M?) black hole ...

... must soften again at higher energies or the pulsar would have easily ... HARD X RAYS, OBSERVATION, X RAY SPECTRA, PULSARS, GAMMA RAYS ...

... ABSTRACT We report OSSE observations of the bursting X-ray pulsar GRO J1744 28 made in December 1995 and January 1996 at hard X-ray ...

Axions thermally emitted by a neutron star would be converted into x rays in the strong magnetic field surrounding the star. An improvement in the observational upper limit of pulsed x rays from the Vela pulsar (PSR 0833-45) by a factor of 12 would constr...

We present results of timing analysis of data of the transient X-ray pulsar 4U 0115+634 (Neu-tron star with fast spin entry) taken by the Rossi X-ray Timing Explorer (RXTE) space satellite. We first time observed the occurrence of 3 QPOs of 3 m Hz, 8 m Hz and 60 m Hz of the X-ray outburst of 2008. In particular the frequencies of the ...

Millisecond pulsars (MSPs) probably achieve their fast rotation by mass transfer from their companion stars in low-mass x-ray binaries (LMXBs). The lack of MSPs and LMXBs rotating near breakup has been attributed to the accretion torque being balanced, at fast rotation, by gravitational radiation, perhaps caused by an unstable ...

4U 2206+54 is a high-mass X-ray binary which has been suspected to contain a neutron star accreting from the wind of its companion, BD +53{sup 0} 2790. Reig et al. have recently detected 5560 s period pulsations in both Rossi X-ray Timing Explorer (RXTE) and International Gamma-ray Astrophysics Laboratory observations which they ...

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 ...

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 ...

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 ...

The Rossi X-ray Timing Explorer has observed a wide range of sources and is producing valuable science. Its broad-band sensitivity has been key in the observations of both compact, stellar, and nebular objects. RXTE is ideally suited for observing X-rays from both galactic and extragalactic black holes. The range of accretion rates, ...

Context: Monitoring of pulse period variations in accreting binary pulsars is an important tool to study the interaction between the magnetosphere of the neutron star and the accretion disk. While the X-ray flux of the brightest X-ray pulsars have been successfully monitored over many years ...

... Title : OSSE Observations of X-Ray Pulsars. ... Descriptors : *X RAYS, *PULSARS, OBSERVATION, LINE ... Subject Categories : ASTROPHYSICS. ...

... Title : Electron-Positron Cascade in Pulsar Outer Gaps,. ... Descriptors : *EMISSION SPECTRA, *PULSARS, REPRINTS, ELECTRONS, X RAY ...

We report the discovery of burst oscillations at the spin frequency in ten thermonuclear bursts from the accreting millisecond X-ray pulsar (AMXP) IGR J17511-3057. The burst oscillation properties are, like those from the persistent AMXPs SAX J1808.4-3658 and XTE J1814-338, anomalous compared to burst oscillations from intermittent ...

A continuous monitoring of the neutron star spin period in Her X-1 and its X-ray luminosity performed with Swift/BAT over the last five years revealed unexpected behavior of the pulsar that appears to switch between two different regimes of the angular momentum exchange between the neutron star and accretion disc. A smooth spin-up of ...

MAXI, the first astronomical payload on JEM-EF of ISS, began operation on August 3, 2009 for monitoring all-sky X-ray images every ISS orbit (92 min). All instruments as well as two main X-ray slit cameras, the GSC and SSC, worked well as expected for one month test operation. The MAXI has been operated since August, 2009 and monitored more than 300 ...

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 ...

It is now ten years ago that the first accreting millisecond X-ray pulsar (AMP) was discovered in the low-mass X-ray binary SAX J1808.4-3658. This RXTE discovery confirmed long-standing predictions that low magnetic field neutron stars can be spun up to high spin frequencies by accretion in ...

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 ...

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 ...

SWIFT J1756.9-2508 is one of the few accreting millisecond pulsars (AMPs) discovered to date. We report here the results of our analysis of its aperiodic X-ray variability, as measured with the Rossi X-Ray Timing Explorer during the 2007 outburst of the source. We detect strong (~35%) flat-topped broadband noise ...

Since 1999, the Rossi X-ray Timing Explorer PCA instrument has monitored the galactic center region. While the original scans covered about 250 sq. deg. of the central galactic bulge region, the monitored region has now grown to more than 700 sq. deg., including the Aquila arm. The principle goals of the program are to detect previously unknown faint X-ray ...

Magnetic energy release plays an important role in a wide variety of cosmic objects such as the Sun, stellar coronae, stellar and galactic accretion disks and pulsars. The observed radio, X-ray and ?-ray emission often directly results from magnetic 'flares', implying that these processes are spatially fragmented and of an impulsive ...

Millisecond pulsars are thought to be neutron stars that have been spun-up by accretion of matter from a binary companion. Although most are in binary systems, some 30% are solitary, and their origin is therefore mysterious. PSR J1719-1438, a 5.7 ms pulsar, was detected in a recent survey with the Parkes 64�m radio telescope. We show ...

Theoretically, the phase transition between the confined and deconfined phases of quarks can have a remarkable effect on the spin properties of millisecond pulsars and on the spin distribution of the population of x-ray neutron stars in low-mass binaries. In the latter class of stars, the effect has already been observed--a strong clustering in the population in a narrow band ...

We report on a Chandra/ACIS-S observation of the eclipsing accretion-powered millisecond pulsar SWIFT J1749.4-2807, which has recently been reported in a fading outburst during 2010 April 11-21 (ATels #2548, #2561, #2565, #2569, #2576, #2579). Our 1080 s observation was made on April 25 (12:25 TT). Using the pulsar orbital parameters ...

Aims: We applied a decomposition method to the energy dependent pulse profiles of the accreting binary pulsar A 0535+26, in order to identify the contribution of the two magnetic poles of the neutron star and to obtain constraints on the geometry of the system and on the beam pattern. Methods: We analyzed pulse profiles obtained from RXTE observations in ...