scholarly journals Discovery of Repetitive Optical Variation Patterns from the Accretion Disk During the 2015 Outbursts of the Black Hole X-Ray Binary V404 Cyg

2018 ◽  
Author(s):  
Mariko Kimura ◽  
Keisuke Isogai ◽  
Taichi Kato ◽  
Yoshihiro Ueda ◽  
Satoshi Nakahira ◽  
...  
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
X Ray ◽  
Variation Patterns ◽  
Optical Variation

scholarly journals Dynamical Evolution of Accretion Flow onto a Black Hole

1998 ◽  
Vol 188 ◽  
pp. 455-456
Author(s):  
M. Yokosawa
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Event Horizon ◽  
Accretion Disk ◽  
Dynamical Evolution ◽  
Galactic Nuclei ◽  
Thick Disk ◽  
X Ray ◽  
General Relativistic ◽  
Inner Region

Active galactic nuclei(AGN) produce many type of active phenomena, powerful X-ray emission, UV hump, narrow beam ejection, gamma-ray emission. Energy of these phenomena is thought to be brought out binding energy between a black hole and surrounding matter. What condition around a black hole produces many type of active phenomena? We investigated dynamical evolution of accretion flow onto a black hole by using a general-relativistic, hydrodynamic code which contains a viscosity based on the alpha-model. We find three types of flow's pattern, depending on thickness of accretion disk. In a case of the thin disk with a thickness less than the radius of the event horizon at the vicinity of a marginally stable orbit, the accreting flow through a surface of the marginally stable orbit becomes thinner due to additional cooling caused by a general-relativistic Roche-lobe overflow and horizontal advection of heat. An accretion disk with a middle thickness, 2rh≤h≤ 3rh, divides into two flows: the upper region of the accreting flow expands into the atmosphere of the black hole, and the inner region of the flow becomes thinner, smoothly accreting onto the black hole. The expansion of the flow generates a dynamically violent structure around the event horizon. The kinetic energy of the violent motion becomes equivalent to the thermal energy of the accreting disk. The shock heating due to violent motion produces a thermally driven wind which flows through the atmosphere above the accretion disk. A very thick disk, 4rh≤h,forms a narrow beam whose energy is largely supplied from hot region generated by shock wave. The accretion flowing through the thick disk,h≥ 2rh, cannot only form a single, laminar flow falling into the black hole, but also produces turbulent-like structure above the event horizon. The middle disk may possibly emit the X-ray radiation observed in active galactic nuclei. The thin disk may produce UV hump of Seyfert galaxy. Thick disk may produce a jet observed in radio galaxy. The thickness of the disk is determined by accretion rate, such ashκ κes/cṁf(r) κ 10rhṁf(r), at the inner region of the disk where the radiation pressure dominates over the gas pressure. Here, Ṁ is the accretion rate and ṁ is the normarized one by the critical-mass flux of the Eddington limit. κesandcare the opacity by electron scattering and the velocity of light.f(r) is a function with a value of unity far from the hole.

scholarly journals Warm and thick corona for a magnetically supported disk in galactic black hole binaries

2020 ◽  
Vol 633 ◽  
pp. A35 ◽  
Author(s):  
D. Gronkiewicz ◽  
A. Różańska
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Accretion Disk ◽  
Thermal Instability ◽  
Stellar Mass ◽  
Rotational Instability ◽  
X Ray ◽  
Black Hole Binaries ◽  
Radiative Processes ◽  
Gas Heating

Context. We self-consistently model a magnetically supported accretion disk around a stellar-mass black hole with a warm optically thick corona based on first principles. We consider the gas heating by magneto-rotational instability dynamo. Aims. Our goal is to show that the proper calculation of the gas heating by magnetic dynamo can build up the warm optically thick corona above the accretion disk around a black hole of stellar mass. Methods. Using the vertical model of the disk supported and heated by the magnetic field together with radiative transfer in hydrostatic and radiative equilibrium, we developed a relaxation numerical scheme that allowed us to compute the transition form the disk to corona in a self-consistent way. Results. We demonstrate here that the warm (up to 5 keV) optically thick (up to 10 τes) Compton-cooled corona can form as a result of magnetic heating. A warm corona like this is stronger in the case of the higher accretion rate and the greater magnetic field strength. The radial extent of the warm corona is limited by local thermal instability, which purely depends on radiative processes. The obtained coronal parameters are in agreement with those constrained from X-ray observations. Conclusions. A warm magnetically supported corona tends to appear in the inner disk regions. It may be responsible for soft X-ray excess seen in accreting sources. For lower accretion rates and weaker magnetic field parameters, thermal instability prevents a warm corona, giving rise to eventual clumpiness or ionized outflow.

Outbursts of the black hole X-ray transient KV UMa (XTE J1118+480) in the optical band

2020 ◽  
Vol 37 ◽  
Author(s):  
Vojtěch Šimon
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Short Duration ◽  
X Ray ◽  
Viscous Instability ◽  
Slow Decline ◽  
The One ◽  
The Individual ◽  
Double Event

Abstract KV UMa (XTE J1118+480) is an X-ray binary that is known to undergo outbursts in 2000 and 2005. This paper presents the discovery of a large outburst starting in 1927 on the archival photographic plates and an analysis of the long-term optical activity of this system. We used the photographic data from DASCH (Digital Access to a Sky Century @ Harvard). We placed the 1927 outburst in the context of the observed outbursts of KV UMa. We show that it is a double event, with a precursor similar to the one of the outbursts in 2000. We find a big difference between the 1927 and 2000 outbursts as regards the length of the gap between the precursor and the main outburst. It is more than 250 d in 1927, whereas it is about 20 d in 2000, although the brightnesses of all peaks are mutually comparable. We also show that the individual optical outbursts of KV UMa differ from each other by the duration of the stage of a slow decline of brightness (sometimes roughly a plateau). This determines the length of the entire main outburst. Both the peak magnitude and the brightness of the outburst when the slow decline transitions to a steep final decaying branch plausibly reproduce in all three outbursts. In the interpretation, the short duration of the precursor is caused by the fact that only the thermal-viscous instability operated in the accretion disk while also the tidal instability of the disk contributed in the subsequent main outburst.

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.

scholarly journals An accretion disk laboratory in the Seyfert 1.9 galaxy NGC 2992

2006 ◽  
Vol 2 (S238) ◽  
pp. 123-126
Author(s):  
Tahir Yaqoob ◽  
Kendrah D. Murphy ◽  
Yuichi Terashima
Keyword(s):  
Black Hole ◽  
Emission Line ◽  
Accretion Disk ◽  
Large Amplitude ◽  
Gravitational Energy ◽  
Test Bed ◽  
Central Black Hole ◽  
X Ray ◽  
Order Of Magnitude ◽  
The Continuum

AbstractOver twenty five years of X-ray observations of the Seyfert 1.9 galaxy NGC 2992 show that it is a promising test-bed for severely constraining accretion disk models. The previous interpretation of the historical activity of NGC 2992 in terms of the accretion disk slowly becoming dormant over many years and then ‘re-building’ itself is not supported by new data. A recent year-long monitoring campaign with RXTE showed that the X-ray continuum varied by more than an order of magnitude on a timescale of weeks. During the large-amplitude flares the centroid energy of the Fe K emission-line complex became significantly redshifted, indicating that the violent activity was occurring close to the putative central black hole where gravitational energy shifts can be sufficiently large. For the continuum, the Compton-y parameter remains roughly constant despite the large-amplitude luminosity variability, with (kT) τ ∼ 20–50.

scholarly journals Imaging Relativistic Radio Jets and the X-ray-Radio Connection in X-ray Transients

1997 ◽  
Vol 163 ◽  
pp. 53-62
Author(s):  
R. M. Hjellming
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
X Ray ◽  
Radio Jets ◽  
Black Hole Accretion ◽  
Relativistic Outflows ◽  
Black Hole Accretion Disk ◽  
Hole Accretion

AbstractThe superluminal radio jets produced by GRO J1655–40 during a series of X-ray outbursts in 1994 were the first indications of a delayed form of relativistic outflows from black hole accretion disk environments. In this paper we review the relation between the radio jets and changes in the X-ray environment for the 1994 events in GRO J1655–40 and compare this behavior with similar X-ray-radio correlations that have since been found in GRS 1716–249, GRS 1739–278, and the 1996 recurrence of another correlated event in GRO 1655–40. We also discuss newly found radio-X-ray correlations in a galactic X-ray binary, Cyg X–3.

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