Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the absorption feature in the prompt X-ray spectrum of GRB 990705   The absorption feature detected in the prompt X-ray emission of GRB 990705
bears important consequences. We investigate different production mechanisms
and we conclude that the absorbing material cannot be very close to the burster
and is likely to be moderately clumped. These properties challenge any model in
which the burst explodes in coincidence with the core-collapse of a massive
rotating star. We show that the straightforward interpretation of the
absorption feature as a photoionization K edge of neutral iron faces a severe
problem in that it requires a huge amount of iron in the close vicinity of the
burster. We then discuss an alternative scenario, in which iron ions are kept
in a high ionization state by the burst flux, and the absorption feature is
produced by resonant scattering from hydrogen-like iron, broadened by a range
outflow velocities. In this case the physical conditions and geometry of the
absorbing material are fully consistent with the presence of a young supernova
remnant surrounding the burst site at a radius R ~ 10^{16} cm. We finally
discuss how this remnant might affect the generation of afterglows with a
standard power-law flux decay.

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The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
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The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
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The categories of this paper are: econ
13
The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
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The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
37
The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn