Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Specifying the Environments around GRB, Explaining the Fe line in the
  X-Ray Afterglow of GRB000214   We present a model explaining the Fe K alpha line and the continuum in the
afterglow of GRB000214. We pose the importance to seek the physically natural
environment around GRB000214. For the reproduction of the observation, we need
the ring-like remnant around the progenitor like that of SN 1987A produced by
the mass-loss of the progenitor and the fireball spread over in every
directions. The observation of GRB000214, in which the continuum power law
spectrum decreased faster than the line, motivated us to consider the two
independent systems for the line emission and the continuum spectrum. At first,
the continuum spectrum can be fitted by the afterglow emission of the fireball
pointing toward the observer which does not collide with the ring because the
emission of GRB and the afterglow are highly collimated to the observer by the
relativistic beaming effect. Secondly, the line can be fitted by the
fluorescence of the Fe atoms in the ring illuminated by the X-ray afterglow.
The significance of this study is that our model may constrain strongly the GRB
model. Although the Supranova model assumes the extreme-ring-like remnant
produced by the usual supernova explosion, this may not be probable. It is
because the supernova remnants are known to be shell-like. The model also
assumes two steps of explosions, on the other hand, we need only one explosion
of the progenitor. In this sense, our scenario is more natural. Moreover, in
the numerical simulations of Hypernova, the jet of the opening angle of only 1
degree is generated. In our model, the fireball which spreads over in every
directions reconciles with the observation of 1 percent of the polarization in
the observation of SN1998bw which showed the explosion might not be so
collimated.

18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex