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

observed in the 650 - 1100 Hz range. Both QPO increased in frequency. together, maintaining a nearly constant frequency separation of about 363 Hz, ...

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 ...

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.

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 ...

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.

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. ...

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 ...

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 ...

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 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 ...

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 ...

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 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 ...

We have shown previously that many of the properties of persistent accretion-powered millisecond pulsars can be understood if their X-ray emitting areas are near their spin axes and move as the accretion rate and structure of the inner disk vary. Here, we show that this 'nearly aligned moving spot model' may also ...

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

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 ...

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 ...

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 ...

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 ...

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 ...

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 pressure of matter and the magnetic field is achieved. At this ...

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 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 ...

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 ...

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 ...

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

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 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 ...

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 ...

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 past twelve years have seen the discovery, with NASA's Rossi X-ray Timing Explorer (RXTE), of several long-predicted phenomena associated with the accretion of matter onto a neutron star in a binary (double) star system. These phenomena are observed in the strong X-ray emission produced by these neutron stars, at luminosities up to ...

Coronal stars Supernova, nova, recurrent nova remnants Timescales of Interest Milliseconds to years notwithstanding, these are now believed to be mostly accreting neutron stars and black holes in interacting binary their data will not be relevant. The hot coronal emission of late type stars is symptomatic of their internal

A neutron star in binary orbit with a low-mass non-degenerate companion becomes a source of x-rays with millisecond variability when mass accretion spins it up. Centrifugally driven changes in density profile may initiate a phase transition in a growing region of the core parallel to what may take place in an isolated millisecond ...

A neutron star in binary orbit with a low-mass non-degenerate companion becomes a source of x-rays with millisecond variability when mass accretion spins it up. Centrifugally driven changes in density profile may initiate a phase transition in a growing region of the core parallel to what may take place in an isolated millisecond ...

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 ...

The basic ideas of accretion onto magnetized neutron stars are outlined. These are applied to a simple model of the structure of the plasma mound sitting at the magnetic poles of such as star, in which upward diffusion of photons is balanced by their downward advection. This steady flow model of the plasma's dynamical state is used to compute the emission of polarized ...

The basic ideas of accretion onto magnetized neutron stars are outlined. These are applied to a simple model of the structure of the plasma mound sitting at the magnetic poles of such as star, in which upward diffusion of photons is balanced by their downward advection. This steady flow model of the plasma`s dynamical state is used to compute the emission of polarized ...

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 ...

X-ray pulses with millisecond-long FWHM have been detected in RXTE (Rossi X-Ray Timing Explorer) satellite observations of Cyg XR-1. Their identity as short-timescale variations in the X-ray luminosity of the source, and not stochastic variability in the X-ray flux, is established by their simultaneous occurrence and similar pulse ...

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 ...

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 ...

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 ...

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, ...

The goal of this investigation is to further our understanding of the dynamics of secreting neutron stars and black holes in the hope of using these systems as probes of the physics of strong gravitational fetus. The main focus of this work has been a multi-year program of simultaneous millisecond X-ray timing and spectral observations carried out with the ...

An evolutionary link between Low Mass X-ray Binaries (LMXBs) and Low Mass Binary Pulsars (LMBPs) has long been proposed. Before the launch of RXTE, the critical missing piece of evidence was the detection of coherent millisecond pulsations from LMXBs that would confirm their millisecond spin rates and essentially confirm the ...

The interest in X/ ?-ray Astronomy has grown enormously in the last decades thanks to the ability to send X-ray space missions above the Earth�s atmosphere. There are more than half a million X-ray sources detected and over a hundred missions (past and currently operational) devoted to the study of cosmic ...

We present X-ray observations of the transient accretion-powered millisecond pulsar IGR J00291+5934 during quiescence. IGR J00291+5934 is the first source among accretion-powered millisecond pulsars to show signs of a thermal component in its quiescent spectrum. Fitting this component with a ...

The goal of this proposal is to perform simultaneous x-ray spectral and millisecond timing observations of accreting neutron stars to further our understanding of their accretion dynamics and in the hope of using these systems as probes of the physics of strong gravitational fields. NAG5-9104 is the successor grant ...

Context. In August 2008, the accreting milli-second X-ray pulsar (AMXP), IGR J00291+5934, underwent an outburst lasting ~100 days, the first since its discovery in 2004. Aims: We present data from the 2008 double-peaked outburst of IGR J00291+5934 from Faulkes Telescope North, the Isaac Newton Telescope, the Keck Telescope, PAIRITEL, ...

We use the XMM-Newton EPIC-pn instrument in timing mode to extend spectral time-lag studies of hard state black hole X-ray binaries into the soft X-ray band. We show that variations of the disc blackbody emission substantially lead variations in the power-law emission, by tenths of a second on variability time-scales of seconds or longer. The large lags ...

We report that the new X-ray transient and accretion-driven millisecond X-ray pulsar XTE J1814-338 (IAUC 8144, ATEL #164 and #165) is at a position consistent with the source EXMS B1810-337 listed in the EXOSAT medium-energy slew survey catalogue (Reynolds et al. 1999, A&AS 134, 287, Table 5). The error box of ...

HETE J1900.1-2455 is a highly peculiar accreting millisecond pulsar, as its pulses disappeared soon after the discovery of the source. Therefore, it can be viewed as a prototype of a system in between pulsating and non pulsating low mass X-ray binaries. We propose to observe it for the first time with XMM-Newton, to discriminate ...

We analyzed the JEM-X light curve (3-35 keV) of the newly discovered accreting millisecond pulsar IGR J17498-2921 (ATEL #3551, #3555, #3556, #3558, #3559) in the time interval from 2011-08-11 22:45 to 2011-08-14 13:41 to look for Type I X-ray bursts. We used bins of 2 s and we searched for excesses of at least three standard ...

We report on the aperiodic X-ray timing and color behavior of the accreting millisecond X-ray pulsar (AMXP) IGR J17511-3057, using all the pointed observations obtained with the Rossi X-Ray Timing Explorer Proportional Counter Array since the source's discovery on 2009 September 12. The source ...

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 accretion through ...

In this Letter we present a new analysis of the torques acting on the accreting millisecond X-ray pulsars SAX J1808.4-3658 and XTE J1814-338, and show how our results can be used to constrain theoretical models of the spin evolution. In particular, we find upper limits on any spin-up/down phase of XTE J1814-338 of |\\dot{\

Results are presented for 10 evolutionary sequences of close binary systems of extreme mass ratio. Angular momentum loss associated with material outflow from the system, a consequence of the ineffectiveness of tidal torques, as well as gravitational radiation is included in the calculations. We find that a previously described mass transfer instability is extremely sensitive to the amount of ...

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

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 ...

The optical counterpart of the transient, millisecond X-ray pulsar SAX J1808.4-3658 was observed in four colours (BVRI) for five weeks during the 2005 June-July outburst. The optical fluxes declined by ~2 mag during the first 16d and then commenced quasi-periodic secondary outbursts, with time-scales of several days, similar to those seen in 2000 and 2002. ...

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

We have obtained high-resolution (approximately 1") deep x-ray images of the globular cluster 47Tucanae (NGC 104) with the Chandra X-ray Observatory to study the population of compact binaries in the high stellar density core. A 70-kilosecond exposure of the cluster reveals a centrally concentrated population of faint (Lx approximately 10(30-33) ergs per ...

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 that it is in a ...

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 (ATel #2569), the ...

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 ...

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 ...

Conclusion: X-rays are mainly external Compton by low-E electrons ... Relativistic jets of AGN are connected to black hole & accretion disk ...

In addition to providing explanations for several X-ray timing and radio properties of accreting sources, the MDAF suggests a model for the infrared flares in the ...

Are simulated X-ray clusters consistent with the observed ones in the outskirts ? ... To study the accretion of primordial gas in cluster DM halos ...

Theory and Modelling Research in the LHEA - Research Topics. Low Mass X-ray Binaries -- Accretion Disk Corona Radiative Transfer � Synthetic X-ray Spectra ...

Are There Soft X-Ray Sources in Galaxies? " The answer is 'yes'': there are many . " Some may be accreting WDs, some may be SNRs, etc. " But a natural model ...

... thin gas illuminated by X-rays. ... INTERACTIONS, THESES, X RAY SPECTRA, HEATING ... Subject Categories : ASTRONOMY ASTROPHYSICS. ...

Phenomenological fits to the hard X-ray spectrum of AM Herculis left unexplained the high equivalent

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 show a structure in the accretion column very different from previous one-zone ...

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 ...

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 show a structure in the accretion column very different from previous one-zone ...

X-ray emission from accreting binary systems (X-ray binaries) uniquely probe the binary phase of stellar evolution and the formation of compact objects such as neutron stars and black holes. A detailed understanding of X-ray binary systems is needed to provide physical insight into the formation and evolution of the stars involved, as ...

We report on the discovery of the second accreting millisecond X-ray pulsar (AMXP) in the globular cluster NGC 6440. Pulsations with a frequency of 205.89 Hz were detected with RXTE on 2009 August 30, October 1 and October 28, during the decays of lsim4 day outbursts of a newly X-ray transient source in NGC 6440. ...

We report on the discovery of the second accreting millisecond X-ray pulsar (AMXP) in the globular cluster NGC 6440. Pulsations with a frequency of 205.89 Hz were detected with RXTE on 2009 August 30, October 1 and October 28, during the decays of {approx}<4 day outbursts of a newly X-ray transient source in ...

Swift J1749.4-2807 is a transient accreting millisecond X-ray pulsars, the first that displayed X-ray eclipses. Therefore it holds a great potential for accurate mass measurements in a low mass X-ray binary system. The determination of the companion star radial velocity would make it possible ...

The outer portion of an accretion disk is examined, taking into account X-ray irradiation within the context of alpha-viscosity. The results show that high and low states are an inherent property of X-ray-irradiated accretion disks. X-ray sources which exhibit transitions characterized by remarkable variations both ...

Sw 1644+57/GRB 110328A is a remarkable cosmological X-ray outburst detected by the {\\it Swift} satellite. Its early-time ($t\\lesssim 0.1$ day since the trigger) X-ray emission resembles some Gamma-Ray Bursts (GRBs), say, GRB 090417B. But the late-time flaring X-ray plateau lasting $> 20$ days renders it unique. We examine the ...

Sw 1644+57/GRB 110328A is a remarkable cosmological X-ray outburst detected by the Swift satellite. Its early-time (t <~ 0.1 days since the trigger) X-ray emission resembles some gamma-ray bursts (GRBs), e.g., GRB 090417B. But the late-time flaring X-ray plateau lasting >40 days renders it unique. We examine the possibilities ...

Dec 31, 2008 ... 2) Accretion also leads to thermonuclear X-ray bursts; brief but bright flashes of thermal X-ray radiation shining through the neutron star ...

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 ...

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, ...

The Rossi X-Ray Timing Explorer observed the soft X-ray transient Aquila X-1 during its outburst in 1997 February and March. We report the discovery of quasi-periodic oscillations (QPOs) in its persistent flux with frequencies in the range of 740-830 Hz, a Q-value of over 100, a fractional rms amplitude of 6.8%+/-0.6% , and nearly coherent oscillations ...

The accretion-powered millisecond pulsar IGR J00291+5934 underwent two ~10 day long outbursts during 2008, separated by 30 days in quiescence. Such a short quiescent period between outbursts has never been seen before from a neutron star X-ray transient. X-ray pulsations at the 599 Hz spin frequency are detected ...

We investigate the role of the compact object in the production of jets from neutron star X-ray binaries. The goal is to quantify the effect of the neutron star spin, if any, in powering the jet. We compile all the available measures or estimates of the neutron star spin frequency in jet-detected neutron star X-ray binaries. We use as an estimate of the ...

We are uncovering significant optical variability in low/hard state observations of several X-ray binaries on the fastest time-scales of just tens of milliseconds typically probed with modern rapid imaging cameras. The optical light curves are remarkable in that they display properties very characteristic of X-ray variations: 1) power spectra with ...

The discovery of millisecond pulsations from neutron stars in low mass X-ray binary (LMXB) systems has substantiated the theoretical prediction that links millisecond radio pulsars (MSRPs) and LMXBs. Since then, the process that produces millisecond radio pulsars from LMXBs, followed by spin-down due to dipole ...

X-ray illuminated accretion disks. We show how the most relevant atomic features in the spectra depend on the assumed properties of the irradiated gas. ...

Spectra of accretion disks in active galactic nuclei & X-ray binaries ... and clean probe of accretion disks and black hole physics in most generic AGN! ...

Sep 10, 2008 ... Intro/Motivation. Ray-Tracing. Disk/Corona Model. Results. Applications. X-Ray Polarization from Accreting Black Holes. Jeremy Schnittman ...

One of the remarkable phenomena, characterizing both Galactic and extra-Galactic X-ray binary systems, is the substantial variability of a photon flux, detectable in a very broad range of timescales. For instance, the accretion flow near a black hole event horizon can produce X-ray variability on a millisecond ...

Recent data on low-mass X-ray binaries (LMXBs) and millisecond pulsars (MSPs) pose a challenge to evolutionary theories which neglect the effects of disk and comparison irradiation. Here we discuss the main features of a radiation-driven (RD) evolutionary model that may be applicable to several LMXBs. According to this model, radiation from the ...

X-ray emitting MHD accretion shocks in classical T Tauri stars. Case for moderate to high plasma-? values

... the hard X-ray Galactic continuum could be the superposition of unresolved point sources such as accreting neutron stars or black holes. ...

... the hard X-ray Galactic continuum could be the superposition of unresolved point sources such as accreting neutron stars or black holes. ...

We reanalyze the 1983 European X-ray Observatory Satellite (EXOSAT) observations of GK Per during an

We propose a 100-ks XMM-Newton observation of the transiently accreting neutron star Swift J1749.4-2807 during its quiescent state. The detection of coherent pulsations at a frequency of 518 Hz and X-ray eclipses recurring every 8.82 h during an outburst observed in 2010 have recently established Swift J1749.4-2807 as the first eclipsing millisecond ...

I review recent work on X-ray sources in Galactic globular clusters, identified with low-mass X-ray binaries (LMXBs), cataclysmic variables (CVs), millisecond pulsars (MSPs) and coronally active binaries by Chandra. Faint transient LMXBs have been identified in several clusters, challenging our understanding of accretion disk ...

The spectral evolution of accretion disks in X-ray binaries containing black holes is studied, based

X-ray flashes from accreting neutron stars are considered. A number of possible explanations for the phenomenon are reviewed. A physical picture is drawn, and numerical models are discussed. 3 figures. (RWR)

How do accretion disks launch winds and jets? From the Fundamental Accretion and Ejection Astrophysics Astro2010. White Paper, Miller et al. ...

Accretion Disk Coronae were first suggested to explain the incomplete eclipses and shallow profiles observed from some Low Mass X-ray Binaries (White and ...

Recent work on a unified model of accretion flows and X-ray emission in low mass X-ray binaries is summarized. In this model, a weakly magnetic neutron star accretes gas simultaneously from a Keplerian disk and a corona above the inner part of the disk. P...

We report the results of XMM-Newton observations of HD 49798/RX J0648.0-4418, the only known X-ray binary consisting of a hot sub-dwarf and a white dwarf. The white dwarf rotates very rapidly (P = 13.2 s) and has a dynamically measured mass of 1.28 � 0.05 M sun. Its X-ray emission consists of a strongly pulsed, soft component, well fit by a blackbody ...

The evolution of binary systems containing weakly magnetized neutron stars can be significantly affected by the illumination of low-mass companions by x rays and, possibly, soft gamma-rays produced during accretion and post-accretion phases. A self-sustained mechanism may keep the radiation-induced mass transfer ...

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 ...

The last ten years have seen significant progress have seen major improvements in our ability to observe and characterize the X-ray emission from black hole systems. In particular, the arrival of a new generation of X-ray satellites that combine large collection area, broad energy response, and flexible monitoring ability (starting with RXTE, BeppoSax, INTEGRAL, and culminating with Suzaku and ...

We present sub-second fast photometry for the high mass X-ray binary Cygnus X-1. We try to observe variability due to instabilities in the accretion process at optical wavelengths. The observations were carried out using the high speed AstraLux camera at the Calar Alto 2.2 m telescope, Spain, in November 2006 and August 2007. We report that the Cygnus X-1 ...

We report a refined solution for the accreting millisecond X-ray pulsar IGR J17498-2921 (ATels #3551, #3555, #3556, #3558, #3559, #3560, #3561, #3562, #3563, #3568). Analysis is based on RXTE PCA data in the energy band 2-30 keV between 2011-08-13 and 2011-08-23, for total exposure of 121 ksec. A coherent orbit solution was found ...

We report the detection of a type I X-ray burst with burst oscillations during an RXTE-PCA observation of the recently discovered accreting millisecond pulsar (AMP) IGR J17498-2921 (ATels #3551, #3555, #3556, #3558, #3559, #3560, #3561, #3562, #3563). The burst intensity peaked on 2011-08-16 at 15:21:45 UTC. We find a rise time of ...

We report on archival Chandra observations of the field containing the currently active accreting millisecond pulsar IGR J17498-2921 (ATels #3351, #3554, #3555, #3558). The observation consists of a 14.2 ks-long ACIS-I image acquired on 2006 Oct 29 23:41 - Oct 30 04:01 TT as part of the bulge Latitude Survey (Grindlay et al. 2005). The data telemetry mode ...

Binary radio pulsars are generally believed to have been spun up to millisecond periods (i.e. recycling) via mass accretion from their donor stars, and they are the descendants of neutron star low-mass X-ray binaries. However, some studies indicate that the formation of pulsars from the accretion-induced collapse ...