Clumpy Outflows from Supercritical Accretion Flow

IUE has been used to study 11 high luminosity X-ray binaries, of which 3 are in the Magellanic Clouds. In the supergiant systems, X-ray ionisation bubbles have been found in most cases, leading to a greater understanding of the winds and accretion processes. Further studies of precessing objects such as LMC X-4 with IUE and ST are clearly of considerable interest, relating to X-ray heating and blanketing. Detailed studies of the Cyg X-l ionisation bubble may resolve the long standing puzzle of its orbit inclination and masses. UV continua have furnished valuable information on extinction, temperatures and luminosities, and the presence of non-stellar (i.e. disk) luminosity. Here too, more detailed studies are clearly indicated for the future. A unique object of interest is the LMC transient 0538-66 whose UV spectrum has quasarlike lines and luminosity which varies oppositely to the visible. This may be a case of supercritical accretion generating an optically thick shell (“disk”) about the pulsar.

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Influence of the geometric configuration of accretion flow on the black hole spin dependence of relativistic acoustic geometry

International Journal of Modern Physics D ◽

10.1142/s0218271818500232 ◽

2018 ◽

Vol 27 (03) ◽

pp. 1850023 ◽

Cited By ~ 2

Author(s):

Pratik Tarafdar ◽

Tapas K. Das

Keyword(s):

Black Hole ◽

Kerr Black Hole ◽

Geometric Configuration ◽

Surface Gravity ◽

Linear Perturbation ◽

Flow Profile ◽

White Hole ◽

Accretion Flow ◽

Black Hole Spin ◽

General Relativistic

Linear perturbation of general relativistic accretion of low angular momentum hydrodynamic fluid onto a Kerr black hole leads to the formation of curved acoustic geometry embedded within the background flow. Characteristic features of such sonic geometry depend on the black hole spin. Such dependence can be probed by studying the correlation of the acoustic surface gravity [Formula: see text] with the Kerr parameter [Formula: see text]. The [Formula: see text]–[Formula: see text] relationship further gets influenced by the geometric configuration of the accretion flow structure. In this work, such influence has been studied for multitransonic shocked accretion where linear perturbation of general relativistic flow profile leads to the formation of two analogue black hole-type horizons formed at the sonic points and one analogue white hole-type horizon which is formed at the shock location producing divergent acoustic surface gravity. Dependence of the [Formula: see text]–[Formula: see text] relationship on the geometric configuration has also been studied for monotransonic accretion, over the entire span of the Kerr parameter including retrograde flow. For accreting astrophysical black holes, the present work thus investigates how the salient features of the embedded relativistic sonic geometry may be determined not only by the background spacetime, but also by the flow configuration of the embedding matter.

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The effects of magnetic field strength on the properties of wind generated from hot accretion flow

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832985 ◽

2018 ◽

Vol 615 ◽

pp. A35 ◽

Cited By ~ 10

Author(s):

De-Fu Bu ◽

Amin Mosallanezhad

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Pressure Gradient ◽

Magnetic Field Strength ◽

Magnetic Pressure ◽

Gas Pressure ◽

Accretion Flow ◽

Accretion Flows ◽

Black Hole Accretion ◽

The Magnetic Field

Context. Observations indicate that wind can be generated in hot accretion flow. Wind generated from weakly magnetized accretion flow has been studied. However, the properties of wind generated from strongly magnetized hot accretion flow have not been studied. Aims. In this paper, we study the properties of wind generated from both weakly and strongly magnetized accretion flow. We focus on how the magnetic field strength affects the wind properties. Methods. We solve steady-state two-dimensional magnetohydrodynamic equations of black hole accretion in the presence of a largescale magnetic field. We assume self-similarity in radial direction. The magnetic field is assumed to be evenly symmetric with the equatorial plane. Results. We find that wind exists in both weakly and strongly magnetized accretion flows. When the magnetic field is weak (magnetic pressure is more than two orders of magnitude smaller than gas pressure), wind is driven by gas pressure gradient and centrifugal forces. When the magnetic field is strong (magnetic pressure is slightly smaller than gas pressure), wind is driven by gas pressure gradient and magnetic pressure gradient forces. The power of wind in the strongly magnetized case is just slightly larger than that in the weakly magnetized case. The power of wind lies in a range PW ~ 10−4–10−3 Ṁinc2, with Ṁin and c being mass inflow rate and speed of light, respectively. The possible role of wind in active galactic nuclei feedback is briefly discussed.

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A radio jet associated with the symbiotic star CH Cygni

Canadian Journal of Physics ◽

10.1139/p86-097 ◽

1986 ◽

Vol 64 (4) ◽

pp. 520-522 ◽

Cited By ~ 1

Author(s):

E. R. Seaquist ◽

A. R. Taylor

Keyword(s):

Electron Density ◽

White Dwarf ◽

Transverse Velocity ◽

Stellar Object ◽

Symbiotic Star ◽

Ionized Gas ◽

Radio Outburst ◽

Supercritical Accretion ◽

End To End ◽

Red Giant

We present observations that show that the symbiotic star CH Cygni recently underwent a strong radio outburst that produced a radio-emitting thermal jet. The jet is two-sided and is expanding lengthwise at an observed rate (end to end) of 1 arcsec/year, corresponding to a transverse velocity of 1100 km∙s−1 in each direction. The electron density on January 22, 1985 exceeded 2 × 106 cm−3, and the mass of the (ionized) gas exceeded [Formula: see text]. The emergence of the jet coincided with a decline in the visual luminosity of [Formula: see text].The data are consistent with a jet produced by supercritical accretion in a binary containing a red giant and a [Formula: see text] white dwarf. The discovery of a jet in such a system provides confirming evidence of the role played by accretion in determining the optical and radio properties of this system. It is also the first expanding jet found to be associated with an evolved stellar object.

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