Stellar mass black holes in the low-hard state may hold clues to jet formation and basic accretion disc physics, but the nature of the accretion flow remains uncertain. A standard thin disc can extend close to the innermost stable circular orbit, but the inner disc may evaporate when the mass accretion rate is reduced. Blackbody-like continuum emission and dynamically broadened iron emission li...

We investigate the accretion disc structure in the strongly Comptonised spectra seen at high luminosities from galactic black holes (variously termed the very high or steep power law dominant state). We use simultaneous ASCA-RXTE data on two such spectra from the black hole transient XTE J1550-564 to constrain the disc and Comptonized luminosity. The broad bandpass of the data gives robust esti...

For a few nearby active nuclei, the disc orbiting the black hole is traced by water maser emission. By combining a simple model together with observed velocity profiles, we show that it is possible to put constraints on the black hole mass and on the distribution of matter (shape, density, size) in the outer disc. We then report possible parameters for the non-keplerian disc and for the black h...

We present an extension of the King et al. [1] model for the flickering of black hole accretion discs by taking proper account for the thermal properties of the disc. First we develop a one-dimensional, vertically averaged, one-zone model for an optically thick accretion disc and study the temporal evolution. This limits the current model to the so-called high/soft state, where the X-Ray spectr...

We model the overall shape of an accretion disc in a semi-detached binary system in which mass is transfered on to a spinning black hole the spin axis of which is misaligned with the orbital rotation axis. We assume the disc is in a steady state. Its outer regions are subject to differential precession caused by tidal torques of the companion star. These tend to align the outer parts of the dis...

This Letter investigates the origin of the asymmetric magnetic field line geometry in the ergospheric disc (and the corresponding asymmetric powerful jet) in 3D perfect magnetohydrodynamic (MHD) numerical simulations of a rapidly rotating black hole accretion system reported in Punsly, Igumenshchev & Hirose. Understanding why and how these unexpected asymmetric structures form is of practical i...

The nature of the interaction between the black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), and the chlorosis it causes to foliage of its pecan [Carya illinoinensis (Wangenh.) K. Koch)] host is poorly understood. Laboratory experiments were conducted on the settling behavior of the black pecan aphid, when provided chlorotic pecan leaf discs resulting from previous bla...

Background: Enterococcus faecalis is reported infrequently as an infectious cause of discitis. In the literature, diagnosis commonly made based on clinical picture coupled with blood cultures, imaging, and tissue cultures. Case Description: A 62-year-old male chronic lower back pain underwent lumbar decompression for a disc. At surgery, patient had significant black discoloration disc material....

The discovery is reported of emission features in the X-ray spectrum of GROJ1655-40 obtained using RossiXTE on 1997, Feb 26. The features have been fitted firstly by two Gaussian lines, which in four spectra have average energies of 5.85± 0.08 keV and 7.32± 0.13 keV, strongly suggestive that these are the red and blue shifted wings of an iron disc line from material with velocity ∼0.33 c. The b...

The 1998 outburst of the bright Galactic black hole binary system XTE J1550 − 564 was used to constrain the accretion disc structure in the strongly Comptonized very high state spectra. These data show that the disc emission is not easily compatible with the constant area L ∝ T 4 behaviour seen during the thermal-dominated high/soft state and weakly Comptonized very high state. Even after corre...