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For the first time in the literature, we establish that
transonic Transonic accretion onto astrophysical black holes is a very interesting example of
classical analogue system found naturally in the Universe. An accreting black hole system
as a classical analogue is unique in the sense that only for such a system,
both kind of horizons, the electromagnetic and the acoustic (generated due to
transonicity of accreting fluid) are simultaneously present in the same system.
Hence accreting astrophysical black holes are the most ideal candidate to study theoretically
and to compare the properties of these two different kind of horizons. Such a
system is also unique in the aspect that
accretion onto the black holes represents the only
classical analogue system found in the nature so far,
where the analogue Hawking temperature
may exceed the actual Hawking temperature.
We also show that acoustic white holes can also be generated if the
accretion flow is multi-transonic and if such
multi-transonic black-hole accretion encounters a stable shock. Such a white hole,
produced at the shock, is always flanked by two acoustic black holes
generated at the inner and the outer sonic points.
Our formalism proves that in general the transonic accretion in astrophysics
can be considered as an example of
the classical analogue gravity model.
Next: Ongoing Work/Future Project
Up: Analogue Gravity Phenomena: Hawking
Previous: Introduction
Tapas Kumar Das
2009-01-17