7,065 research outputs found
Black Hole Accretion: From Quasars to Nano-Quasars
In this review we shall comment on a few recent findings which strengthen the
view that the black hole accretion has substantial amount of sub-Keplerian
component. The manifestation of this component is many fold. We discuss some of
them. A general outline of the complex structure that emerges from the
multitude of observations is presented. A detailed outline of what might be
going on in outburst sources is also discussed. The relationship amount the
spectral and timing properties can be best understood by this picture. We claim
that the sub-Keplerian advective disk paradigm is a complete package. Since
signatures of sub-Keplerian motion is already increasing in the literature, the
whole package must be correct.Comment: 7 Pages, 2 Figures, Proceeding of the 2nd Kolkata Conference on
"Observational Evidence for the Black Holes in the Universe", Published in
AIP, 200
Universal canonical black hole entropy
Non-rotating black holes in three and four dimensions are shown to possess a
canonical entropy obeying the Bekenstein-Hawking area law together with a
leading correction (for large horizon areas) given by the logarithm of the area
with a {\it universal} finite negative coefficient, provided one assumes that
the quantum black hole mass spectrum has a power law relation with the quantum
area spectrum found in Non-perturbative Canonical Quantum General Relativity.
The thermal instability associated with asymptotically flat black holes appears
in the appropriate domain for the index characterising this power law relation,
where the canonical entropy (free energy) is seen to turn complex.Comment: Revtex, 5 pages, no figures. Typos corrected and a footnote and some
references adde
Spectral Properties of M87 Using Two-Component Flow
We fit the observational data for M87 using two-component advective disk
model. We show that the flat spectrum from the nucleus of M87 is due to
synchrotron radiation produced by non-thermal electrons in the CENBOL. The
non-thermal distribution is produced due to acceleration of electrons across
the shock in a sub-Keplerian flow.Comment: 4 Pages, 1 Figures, Proceeding of the 2nd Kolkata Conference on
"Observational Evidence for the Black Holes in the Universe", Published in
AIP, 200
Black hole mass measurements using ionized gas discs: systematic dust effects
Using detailed Monte Carlo radiative transfer simulations in realistic models
for galactic nuclei, we investigate the influence of interstellar dust in
ionized gas discs on the rotation curves and the resulting black hole mass
measurements. We find that absorption and scattering by interstellar dust
leaves the shape of the rotation curves basically unaltered, but slightly
decreases the central slope of the rotation curves. As a result, the "observed"
black hole masses are systematically underestimated by some 10 to 20% for
realistic optical depths. We therefore argue that the systematic effect of dust
attenuation should be taken into account when estimating SMBH masses using
ionized gas kinematics.Comment: 4 pages, 2 figures, to appear in "Observational Evidence for Black
Holes in the Universe", AIP Conference Proceeding
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