Cygnus X-1 - A two-temperature accretion disk model which explains the observed hard X-ray spectrum

1975 ◽  
Vol 199 ◽  
pp. L153 ◽  
Author(s):  
D. M. Eardley ◽  
A. P. Lightman ◽  
S. L. Shapiro
Keyword(s):  
Accretion Disk ◽  
Disk Model ◽  
X Ray ◽  
Two Temperature

scholarly journals Hybrid Accretion-Disks in AGN and the AGN Contribution to the XRB

1994 ◽  
Vol 159 ◽  
pp. 491-491
Author(s):  
Amri Wandel
Keyword(s):  
Accretion Disk ◽  
Accretion Disks ◽  
Power Law ◽  
Accretion Rate ◽  
Bremsstrahlung Spectrum ◽  
Spectral Evolution ◽  
X Ray ◽  
X Ray Background ◽  
Inner Region ◽  
Two Temperature

The hybrid accretion-disk (HAD) model links the two characteristic components of AGN spectra – the UV bump and the X-ray power-law – in the framework of one physical model. The radially stratified hybrid disk is a self consistent combination of a thin, cool accretion disk at large radii, with an inner hot two-temperature disk. Its spectrum consists of three components, corresponding to the three radial disk regions: a blackbody thermal spectrum from the outer cool disk, a Comptonized soft photon power-law spectrum from the intermediate region, and a thermal Comptonized bremsstrahlung spectrum from the inner region. The dependence of the hybrid disk spectrum on the accretion rate and on other parameters is discussed and applied to AGN spectral evolution, and in particular to explaining the cosmic X-ray background by AGN.

scholarly journals The Accretion Disk Model for the First Hundred Days of the Outburst Evolution in the Black Hole X-Ray Novae

1996 ◽  
Vol 158 ◽  
pp. 139-140
Author(s):  
S.-W. Kim ◽  
J. C. Wheeler ◽  
S. Mineshige
Keyword(s):  
Mass Transfer ◽  
Black Hole ◽  
Accretion Disk ◽  
Mass Transfer Rate ◽  
Time Dependent ◽  
Disk Model ◽  
X Ray ◽  
Outer Disk ◽  
Appreciable Increase ◽  
Shadowing Effect

We present time-dependent, irradiated, accretion disk models for the black hole X-ray novae in the first hundred days of the dwarf nova-like outbursts, including the rise, precursor, maximum and the secondary re-flare. This work is based on the disk instability model (Kim, Mineshige & Wheeler 1996, Kim, Wheeler & Mineshige 1996). The model is reasonably consistent with the observed optical light curves. The irradiators are the central hot region around the black hole, and the corona or chromosphere above the accretion disk. In addition, we include the time-dependent shadowing effect and consequent blocking of the outer portions of the disk from the central irradiator. We find the stagnation phenomenon whereby the disk stays in the intermediate temperature stage between the hot and cool state. This can explain the recently discovered optical precursor rise prior to the maximum light in Nova Sco 1994 (Bailyn et al. 1995: see Fig. 1). We suggest the secondary re-flare after the maximum is due to the coupled effects of the irradiation and stagnation. In the model, the stagnation phenomenon during the rise results from the partial ionization and molecular opacity. In addition, we find irradiation-induced stagnation during the decay phase, which is consistent with the observed secondary re-flare in X-ray novae (see Fig. 1). In the overall evolution of model outbursts in the first hundred days, the outer disk is blocked from the irradiation and, in turn, the companion star may not be strongly irradiated. This suggests that there is no appreciable increase of mass transfer rate during the decay prior to the secondary re-flare, unlike the behaviour in the mass transfer burst models.

A two-temperature accretion disk model for Cygnus X-1 - Structure and spectrum

1976 ◽  
Vol 204 ◽  
pp. 187 ◽  
Author(s):  
S. L. Shapiro ◽  
A. P. Lightman ◽  
D. M. Eardley
Keyword(s):  
Accretion Disk ◽  
Disk Model ◽  
Two Temperature

scholarly journals X-Ray Fluctuations from the Advection-Dominated Accretion Disk with a Critical Behavior

1998 ◽  
Vol 188 ◽  
pp. 404-405
Author(s):  
M. Takeuchi
Keyword(s):  
Fluid Dynamics ◽  
Accretion Disk ◽  
Critical Behavior ◽  
Disk Model ◽  
New Model ◽  
X Ray

The new model for X-ray fluctuations of Cyg X-1, which is based on the fluid dynamics, is presented. The model is the optically thin and advection-dominated accretion disk model, which has a critical behavior.

scholarly journals The Solution of the X-Ray Heating Light Curve for 4U2129+47/V1727 Cyg

1987 ◽  
Vol 93 ◽  
pp. 701-705
Author(s):  
K. Pavlovski
Keyword(s):  
Light Curve ◽  
Accretion Disk ◽  
Model Parameters ◽  
Disk Model ◽  
X Ray ◽  
Reliable Solution ◽  
Best Fit

AbstractThe X-ray heating light curve of the binary X-ray source 4U2129+47/V1727 Cgy is synthesized. A reliable solution is obtained only after accounting for the influence of an accretion disk. Model parameters achieved by the best fit are discussed. The solution is also discussed in the context of an extended OFF state.

scholarly journals Accretion Onto the Neutron Star in Be/X-ray Binaries

2004 ◽  
Vol 218 ◽  
pp. 449-450
Author(s):  
Kimitake Hayasaki ◽  
Atsuo T. Okazaki
Keyword(s):  
Neutron Star ◽  
High Resolution ◽  
Accretion Disk ◽  
Time Dependent ◽  
Disk Model ◽  
X Ray ◽  
Short Period ◽  
Be Star ◽  
X Ray Binaries ◽  
Resolution Simulation

We study accretion onto the neutron star in Be/X-ray binaries, using a 3D SPH code and the data imported from a high resolution simulation by Okazaki et al. (2002) for a coplanar system with a short period (Porb = 24.3 d) and moderate eccentricity (e = 0.34). We find that a time-dependent accretion disk is formed around the neutron star in Be/X-ray binaries. The disk shrinks after the periastron passage of the Be star and restores its radius afterwards. Our simulations show that the truncated Be disk model for Be/X-ray binaries is consistent with the observed X-ray behavior.

scholarly journals Variability and Spectra of AGN in the EUV and the Relation to Other Bands

1996 ◽  
Vol 152 ◽  
pp. 63-67
Author(s):  
Herman L. Marshall
Keyword(s):  
Accretion Disk ◽  
Polarization Measurement ◽  
Emission Lines ◽  
Optical Data ◽  
No Emission ◽  
Disk Model ◽  
Temperature Variations ◽  
X Ray ◽  
Ngc 5548 ◽  
Euv Spectrum

Data from several collaborations will be shown which demonstrate the utility of EUVE observations. For Mk 478, a Seyfert 1 galaxy, the rapidly variable EUV flux is shown to have a steep, featureless continuum. The EUV data are combined with UV and optical data to form an overall spectrum that is consistent with an accretion disk model; slight temperature variations in the innermost regions could cause the large EUV flux changes. EUVE data for other sources are presented: NGC 5548, which shows significant variations and has an EUV spectrum that shows no emission lines, contrary to a previous report; 3C 273, which did not vary much; and PKS 2155-304, which was observed simultaneously with ASCA and IUE when a hard X-ray flare was detected as an EUV polarization measurement was being attempted.

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