295 research outputs found
Role of shocked accretion flows in regulating the QPO of galactic black hole candidates
Using a generalized non-spherical, multi-transonic accretion flow model, we
analytically calculate the normalized QPO frequency
of galactic black hole candidates in terms of dynamical flow variables and
self-consistently study the dependence of on such
variables. Our results are in fairly close agreement with the observed QPO
frequencies of GRS 1915+105. We find that is quite
sensitive to various parameters describing the black hole accretion flow
containing dissipative and non-dissipative shock waves. Thus the QPO phenomena
is, {\it indeed}, regulated by `shocked' black hole accretion, and, for the
first time, we establish a definitive connection between the QPO frequency and
the properties of advective BH accretion flows. This information may provide
the explanation of some important observations of galactic micro quasars.Comment: Final version accepted for publication in the Astrophysical Journal
Letters (ApJL). A considerable part of the paper is almost completely
re-written, though the results and the final conclussions are the same. One
can now ignore the previous version. 8 pages with four black and white
figures. For high resolution Fig. 3, please mail the author
<[email protected]
One Parameter Solution of Spherically Symmetric Accretion in Various Pseudo-Schwarzschild Potentials
In this paper we have solved the hydrodynamic equations governing the
spherically symmetric isothermal accretion (wind) onto (away from) compact
objects using various pseudo-Schwarzschild potentials.These solutions are
essentially one parameter solutions in a sense that all relevant dynamical as
well as thermodynamic quantities for such a flow could be obtained (with the
assumption of a one-temperature fluid) if {\it only one} flow parameter
(temperature of the flow ) is given. Also we have investigated the transonic
behaviour of such a flow and showed that for a given , transitions from
subsonic to the supersonic branch of accretion (wind) takes place at different
locations depending on the potentials used to study the flow and we have
identified these transition zones for flows in various such potentials.Comment: 9 pages, 3 black and white post-script figures. Published in the
International Journal of Modern Physics D (IJMPD
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