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 ...
NASA Astrophysics Data System (ADS)
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 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 ...
Energy Citations Database
... Understanding of accretion disks, accretion flows, X-ray induced winds, compact obect evolution are all in a primitive state. ...
NASA Website
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
NASA Technical Reports Server (NTRS)
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. ...
DTIC Science & Technology
Phenomenological fits to the hard X-ray spectrum of AM Herculis left unexplained the high equivalent
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 ...
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 ...
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 ...
X-ray emitting MHD accretion shocks in classical T Tauri stars. Case for moderate to high plasma-? values
E-print Network
... 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
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...
National Technical Information Service (NTIS)
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 ...
accreting star. Roughly half the known X�ray novae contain BH candidates and the rest contain NSs. X of the accreting star. As discussed in the Introduction, the accretion rate in a typical X�ray nova spans a wide in which the compact accreting primary stars are too ...
The Ginga observations of GX333-4 are examined. Two components were detected in the X ray spectrum: the X rays from an accreting disk and a hard tail component, whose energy spectrum can be represented by a Compton scattering model. The X rays showed ...
X-rays from young stellar objects can influence the physical properties of their surroundings. A particularly interesting example is the ionization of the accretion disk by hard X-rays at distances of the order of 1 AU or more. The authors show that X-rays induce a layered ionization structure in which the outer layer is sufficiently ...
Two new elements, the Hybrid Accretion Disk (HAD) model and the Rosat survey of resolved X-ray sources and diffuse background, are combined in an attempt to resolve the long standing problem of the cosmic X-Ray Background (XRB), explaining the diffuse XRB...
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 ...
Classical T Tauri stars (CTTS) are young, accreting systems. The accretion is thought to cause a soft X-ray excess and unusual line ratios in the He-like triplets. The accretion spots can also be seen with optical Doppler-imaging; however, the final test to correlate these signatures - simultaneous ...
A model of the X-ray radiation emitted from the accretion column of a compact object in AM Herculis binaries, using Monte Carlo methods is presented. The accretion column in the model has cylindrical symmetry. Above a shocked region in the column there is...
We examine the role of the accretion disk in the steady-burning white dwarf model for supersoft sources. The accretion luminosity of the disk is quite small compared to the nuclear burning luminosity of the central source. Thus, in contrast to standard ac...
Too hot accretion disks in ULX and superluminal jet sources ... Standard accretion disk around Kerr black hole can explain the hard disk spectra? ...
Mar 12, 2005 ... Accretion Disk Simulation Credit: Michael Owen, John Blondin ... Such accretion disks power bright x-ray sources within our own galaxy. ...
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...
Periodic flares and dips in the Active Galactic Nuclei (AGN) X-ray light curves are explained by bright spots on an accretion disk surface. For a disk seen almost edge-on the spots are eclipsed or Doppler beamed and this occasionally produces short sequen...
Jan 26, 2000 ... Left: This false-color X-ray picture from the Chandra X-ray Observatory ... that the temperature of its accretion disk was just one million degrees. ...
factor of 4 between the two observations separated by 12 days suggests that the X-rays .... nature of the intrinsic X-ray weakness and present an accretion ...
whose quiescent X-ray emission appears to be completely dominated by accretion. Subject headinggs: stars: emission-line, Be stars: individual (HD 163296) ...
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 ...
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...
The prime scientific objectives of the Rossi X-Ray Timing Explorer (RXTE) were the study of astrophysical compact objects: black holes (galactic and extragalactic), many types of neutron stars, and accreting white dwarfs. RXTE was successful in achieving ...
Jan 13, 2011 ... The neutron star surface will be probed via X-ray absorption spectroscopy: metals deposited at the surface via accretion provide spectroscopic ...
Jan 13, 2011 ... High-resolution X-ray spectra of bursting, accreting neutron stars show redshifted absorption lines that reveal the neutron star mass and ...
Dec 31, 2008 ... It is known from observations of burst oscillations that some of these accreting neutron stars produce an X-ray hot spot during some X-ray ...
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...
We received Type A and B funding under the NASA Astrophysics Data Program for the analysis and interpretation of hard x-ray data obtained by the Rossi X-ray Timing Explorer and other NASA sponsored missions for Intermediate Polars (IPS) and Polars. For so...
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 binaries, rotation ...
Accretion disks are invoked to explain a host of astrophysical phenomena, from protostellar objects to AGN. And yet the mechanism allowing accretion disks to operate are completely unknown. This proposal seeks to observe the ``smoking gun'' signature of magnetically-driven viscosity in accretion disks. Magnetically-induced viscosity is ...
It is shown by Monte Carlo simulation that high-energy X-rays are produced through Compton scattering in a boundary layer of an accreting neutron star. The following is the mechanism for the high-energy X-ray production. An accreting neutron star has a boundary layer rotating rapidly on the surface. ...
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 ...
Canizares et al. (1979) have reported the detection of the O VIII Lyman-alpha line from the vicinity
iron K absorption edge. This decline is too broad for a single edge, and instead ... constrain the iron K absorption feature evident in Figure 6. ...
Jun 19, 2006 ... Long Term Intensity Variations in X-ray Binaries ... has led to a number of new insights into accretion onto magnetized neutron stars. ...
Dec 20, 2010 ... The physical process of viscous dissipation in accretion disks is poorly ... More sophisticated approaches which regard viscosity to be the ...
Analytical arguments and a numerical hydrodynamic code are used to investigate spherically symmetric
Unstable thermonuclear ignition of accreted fuel on neu- tron stars (NSs) in low -mass X-ray binaries (LMXBs) is triggered once a critical column density is ...
the accretion disk of the binary system and inconsistent with narrow beaming. ... luminosities are time-averaged estimates, which is critical for variable ...
the inner accretion disk in response to irradiation by the hard X-ray source ( Tanaka et al. 1995). The strongest feature in this reflection spectrum is the ...
In analogy the soft component probably originates from an accretion-heated surface region around the white dwarfs magnetic pole(s). ...
Downsizing. X-ray surveys result (discovered in X-rays first!) Massive black holes actively accreting at early times in Universe ...
neutron stars would have important implications for nuclear and particle physics. While many of these objects are in binary systems ( X-ray binaries ), where ...
Accreting compact object; Eddington-limited outbursts (rise of days; duration of weeks; recurrence of decades); Superluminal jets; Quiescent light dominated ...
Within the framework of unsaturated Compton disk accretion onto a supermassive black hole as a model
We perform computations using a time-dependent model for the accretion disk limit-cycle mechanism to
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. ...
observed in the 650 - 1100 Hz range. Both QPO increased in frequency. together, maintaining a nearly constant frequency separation of about 363 Hz, ...
Dec 31, 2008 ... The line widths are influenced by rotation of the star via the Doppler effect. Since the spin rates of many of these accreting neutron stars ...
Dec 31, 2008 ... A particularly powerful diagnostic is possible with very rapidly rotating black holes: the accretion disk capable of producing line emission ...
Star clusters/ULX associations? Survival or dispersion of protoclusters. What is the mass of the accreting BHs in ULXs? From: luminosity. X-ray colors ...
Sep 7, 2004 ... Because of this, the accretion curtain does not cross the line of sight, explaining the energy independence of the saw-toothed hard X-ray ...
May 4, 2007 ... Because of this, the accretion curtain does not cross the line of sight, explaining the energy independence of the saw-toothed hard X-ray ...
Apr 22, 2011 ... He is constraining the physics of black hole accretion, outflows and ... multiwavelength observations (including X-rays and gamma-rays) in ...
The resulting microradiographs were developed and the film digitized using a high resolution scanner to extract fine detail in the radiographs. ...
Jan 14, 2005 ... [C] They contain accretion 'columns' and 'curtains' [D] All of the above. What are super-soft sources? [A] X-ray emitting objects that are ...
BATSE Bright Source Monitor (Pulsed Sources). Frequency & Flux Histories ... 20 transient accreting X-ray binaries since the beginning of the CGRO mission, ...
... index to significant articles, news items, and ... incorporates several new physical elements: (1 ... MOMENTS, RADIO SOURCES(ASTRONOMY), X RAY ...
Dec 31, 2008 ... These X-ray sources are accreting supermassive black holes (AGN) that together are the integrated fossil signature of massive black hole ...
