Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gamma-Ray Bursts as Hypernovae   The energetics of optical and radio afterglows following BeppoSAX and BATSE
gamma-ray bursts (GRBs) suggests that gamma-ray emission is not narrowly
collimated, but a moderate beaming is possible, so the total energy of a GRB
may be in the range 10^{50} - 10^{51} erg. All attempts to generate a fireball
powered by neutrino-antineutrino annihilation have failed so far, and a rapid
rotation combined with a magnetic field of $ \sim 10^{15} $ gauss gains
popularity.
  In this paper a hypernova scenario is described: a collapse of a massive
member in a close binary system, similar to the `failed' Type Ib supernova
model proposed by Woosley (1993). The collapse may lead to explosion, with
energy transmitted from the rapidly spinning hot neutron core or black hole to
the envelope by a strong magnetic field, as in a supernova model proposed by
Ostriker and Gunn (1971). However, because of a large mass and rapid rotation
of the core the explosion of a hypernova may release up to 10^{54} erg of
kinetic energy, creating a `dirty' fireball.
  In this scenario a moderately non-spherical explosion may accelerate a very
small fraction of matter to a very large Lorentz factor, and this may give rise
to a gamma-ray burst and its afterglow, just like in a conventional fireball
model. However, the highest velocity ejecta from a hypernova are followed with
matter which expands less rapidly but carries the bulk of kinetic energy,
providing a long term power source for the afterglow. If the afterglows remain
luminous for a very long time then the proposed hypernova scenario may provide
an explanation. Pre-hypernovae, being massive stars, are likely to be located
in the young, star forming regions.

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The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
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The categories of this paper are: math
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: mtrl-th
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The categories of this paper are: gr-qc