The Structure and X‐Ray Recombination Emission of a Centrally Illuminated Accretion Disk Atmosphere and Corona

2002 ◽  
Vol 581 (2) ◽  
pp. 1297-1327 ◽  
Author(s):  
M. A. Jimenez‐Garate ◽  
J. C. Raymond ◽  
D. A. Liedahl
Keyword(s):  
Accretion Disk ◽  
X Ray ◽  
Recombination Emission

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

4U 1608–52 as a quasi-persistent X-ray source

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Vojtěch Šimon
Keyword(s):  
Accretion Disk ◽  
Time Segment ◽  
X Ray ◽  
Band Emission ◽  
Heating And Cooling ◽  
Soft State ◽  
Cyclic Variations ◽  
Low Mass ◽  
X Ray Binaries ◽  
Disk Region

Abstract 4U 1608–52 is a soft X-ray transient. The analysis presented here of a particular part of its X-ray activity uses observations of RXTE/ASM and Swift/BAT. We show a time segment (MJD 54262–MJD 55090) (828 d) in which 4U 1608–52 behaved as a quasi-persistent X-ray source with a series of bumps, with a complicated relation between the evolution of fluxes in the soft (1.5–12 keV) and the hard (15–50 keV) X-ray regions. We ascribe these bumps to a series of propagations of heating and cooling fronts over the inner disk region without any transitions to the true quiescence. 4U 1608–52 oscillated around the boundary between the dominance of the Comptonized component and the dominance of the multicolor accretion disk in its luminosity. Only some of the bumps in this series were accompanied by a transition from the hard to the soft state; if it occurred, it displayed a strong hysteresis effect. The hard-band emission with the dominant Comptonized component was present for most of this active state and showed a cycle of about 40 d. We argue that the cyclic variations of flux come from the inner disk region, not, e.g., from a jet. We also discuss the observed behavior of 4U 1608–52 in the context of other quasi-persistent low-mass X-ray binaries.

scholarly journals X-ray Properties of 3C 111: Separation of Primary Nuclear Emission and Jet Continuum

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 219
Author(s):  
Elena Fedorova ◽  
B.I. Hnatyk ◽  
V.I. Zhdanov ◽  
A. Del Popolo
Keyword(s):  
Accretion Disk ◽  
Power Law ◽  
Line Emission ◽  
High Energy ◽  
Power Law Model ◽  
X Ray ◽  
Additional Information ◽  
Observational Dataset ◽  
Simple Power ◽  
Photon Index

3C111 is BLRG with signatures of both FSRQ and Sy1 in X-ray spectrum. The significant X-ray observational dataset was collected for it by INTEGRAL, XMM-Newton, SWIFT, Suzaku and others. The overall X-ray spectrum of 3C 111 shows signs of a peculiarity with the large value of the high-energy cut-off typical rather for RQ AGN, probably due to the jet contamination. Separating the jet counterpart in the X-ray spectrum of 3C 111 from the primary nuclear counterpart can answer the question is this nucleus truly peculiar or this is a fake “peculiarity” due to a significant jet contribution. In view of this question, our aim is to estimate separately the accretion disk/corona and non-thermal jet emission in the 3C 111 X-ray spectra within different observational periods. To separate the disk/corona and jet contributions in total continuum, we use the idea that radio and X-ray spectra of jet emission can be described by a simple power-law model with the same photon index. This additional information allows us to derive rather accurate values of these contributions. In order to test these results, we also consider relations between the nuclear continuum and the line emission.

AGN torus threaded by large scale magnetic field

2018 ◽  
Vol 27 (10) ◽  
pp. 1844006
Author(s):  
A. Dorodnitsyn ◽  
T. Kallman
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Accretion Disk ◽  
Large Scale ◽  
Three Dimensional ◽  
X Ray ◽  
Radiative Feedback ◽  
Large Scale Magnetic Field ◽  
Three Dimensional Simulations

Large scale magnetic field can be easily dragged from galactic scales toward AGN along with accreting gas. There, it can contribute to both the formation of AGN “torus” and help to remove angular momentum from the gas which fuels AGN accretion disk. However the dynamics of such gas is also strongly influenced by the radiative feedback from the inner accretion disk. Here we present results from the three-dimensional simulations of pc-scale accretion which is exposed to intense X-ray heating.

scholarly journals A tale of two periods: determination of the orbital ephemeris of the super-Eddington pulsar NGC 7793 P13

2018 ◽  
Vol 616 ◽  
pp. A186 ◽  
Author(s):  
F. Fürst ◽  
D. J. Walton ◽  
M. Heida ◽  
F. A. Harrison ◽  
D. Barret ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Orbital Period ◽  
Timing Analysis ◽  
X Ray ◽  
System Parameters ◽  
Orbital Resonance ◽  
Photometric Period ◽  
Orbital Periods ◽  
Analyze Data

We present a timing analysis of multiple XMM-Newton and NuSTAR observations of the ultra-luminous pulsar NGC 7793 P13 spread over its 65 d variability period. We use the measured pulse periods to determine the orbital ephemeris, confirm a long orbital period with Porb = 63.9+0.5−0.6 d, and find an eccentricity of e ≤ 0.15. The orbital signature is imprinted on top of a secular spin-up, which seems to get faster as the source becomes brighter. We also analyze data from dense monitoring of the source with Swift and find an optical photometric period of 63.9 ± 0.5 d and an X-ray flux period of 66.8 ± 0.4 d. The optical period is consistent with the orbital period, while the X-ray flux period is significantly longer. We discuss possible reasons for this discrepancy, which could be due to a super-orbital period caused by a precessing accretion disk or an orbital resonance. We put the orbital period of P13 into context with the orbital periods implied for two other ultra-luminous pulsars, M82 X-2 and NGC 5907 ULX, and discuss possible implications for the system parameters.

scholarly journals Quasi-simultaneous Radio/X-Ray Observations of the Candidate Transitional Millisecond Pulsar 3FGL J1544.6−1125 during its Low-luminosity Accretion-disk State

2021 ◽  
Vol 923 (1) ◽  
pp. 3
Author(s):  
Amruta D. Jaodand ◽  
Adam T. Deller ◽  
Nina Gusinskaia ◽  
Jason W. T. Hessels ◽  
James C. A. Miller-Jones ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Large Array ◽  
Millisecond Pulsar ◽  
Very Large Array ◽  
X Ray ◽  
Upper Limit ◽  
5 Ghz ◽  
Variable Radio

Abstract 3FGL J1544.6−1125 is a candidate transitional millisecond pulsar (tMSP). Similar to the well-established tMSPs—PSR J1023+0038, IGR J18245−2452, and XSS J12270−4859—3FGL J1544.6−1125 shows γ-ray emission and discrete X-ray “low” and “high” modes during its low-luminosity accretion-disk state. Coordinated radio/X-ray observations of PSR J1023+0038 in its current low-luminosity accretion-disk state showed rapidly variable radio continuum emission—possibly originating from a compact, self-absorbed jet, the “propellering” of accretion material, and/or pulsar moding. 3FGL J1544.6−1125 is currently the only other (candidate) tMSP system in this state, and can be studied to see whether tMSPs are typically radio-loud compared to other neutron star binaries. In this work, we present a quasi-simultaneous Very Large Array and Swift radio/X-ray campaign on 3FGL J1544.6−1125. We detect 10 GHz radio emission varying in flux density from 47.7 ± 6.0 μJy down to ≲15 μJy (3σ upper limit) at four epochs spanning three weeks. At the brightest epoch, the radio luminosity is L 5 GHz = (2.17 ± 0.17) × 1027 erg s−1 for a quasi-simultaneous X-ray luminosity L 2–10 keV = (4.32 ± 0.23) × 1033 erg s−1 (for an assumed distance of 3.8 kpc). These luminosities are close to those of PSR J1023+0038, and the results strengthen the case that 3FGL J1544.6−1125 is a tMSP showing similar phenomenology to PSR J1023+0038.

scholarly journals Orbital motion and quasi-quantized disk around rotating neutron stars

2014 ◽  
Vol 23 (06) ◽  
pp. 1450053 ◽  
Author(s):  
Joan Jing Wang ◽  
Hsiang-Kuang Chang
Keyword(s):  
Accretion Disk ◽  
Orbital Motion ◽  
Photon Polarization ◽  
X Ray ◽  
Frame Dragging ◽  
Accretion Flows ◽  
Promising Tool ◽  
Disk Structure ◽  
Low Mass ◽  
Inner Region

In accreting neutron star (NS) low-mass X-ray binary (LMXB) systems, NS accretes material from its low-mass companion via a Keplerian disk. In a viscous accretion disk, inflows orbit the NS and spiral in due to dissipative processes, such as the viscous process and collisions of elements. The dynamics of accretion flows in the inner region of an accretion disk is significantly affected by the rotation of NS. The rotation makes NS, thus the spacetime metric, deviate from the originally spherical symmetry, and leads to gravitational quadrupole, on one hand. On the other hand, a rotating NS drags the local inertial frame in its vicinity, which is known as the rotational frame-dragging effect. In this paper, we investigate the orbital motion of accretion flows of accreting NS/LMXBs and demonstrate that the rotational effects of NS result in a band of quasi-quantized structure in the inner region of the accretion disk, which is different, in nature, from the scenario in the strong gravity of black hole arising from the resonance for frequencies related to epicyclic and orbital motions. We also demonstrate that such a disk structure may account for frequencies seen in X-ray variability, such as quasi-periodic oscillations (QPOs), and can be a potential promising tool for the investigation of photon polarization.

scholarly journals Hardness Ratio in Evolving Low-Mass X-ray Binary Systems

1987 ◽  
Vol 125 ◽  
pp. 199-199
Author(s):  
J. Shaham ◽  
M. Tavani
Keyword(s):  
Neutron Star ◽  
Accretion Disk ◽  
Binary Systems ◽  
Spectral Component ◽  
Soft Component ◽  
Hard Component ◽  
X Ray ◽  
Low Mass ◽  
Additional Support ◽  
X Ray Binaries

Spectral observations of low-mass X-ray binaries (LMXBs) show that the soft component usually dominates over the hard one. These results provide additional support to an interpretation based on models of LMXBs in which the neutron star while, on the average, spinning up, is also experiencing a spinning down torque. Under these conditions, a fraction of the luminosity associated with the gravitational release of energy on the surface of the accreting neutron star may manifest itself as luminosity originating in the inner part of the accretion disk. It is probably possible to separate the two contributions; the stellar luminosity can be associated with the hard component of the spectrum and the disk luminosity, related to the exchange of energy due to the torque between the rapidly spinning neutron star and the accretion disk, can be associated with the soft spectral component.

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