Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: GRBs: when do blackbody spectra look like non-thermal ones?   We argue that a nonthermally looking spectrum of a gamma-ray burst (GRB) can
be formed as a superposition of a set of thermal blackbody spectra. This
superposition may be done by time integration which is present even in `time
resolved' GRB spectroscopy. A nonthermal spectrum can be obtained also by the
space integration which should take place unless all the emission comes from a
plane front moving exactly towards the observer. We propose a model of the
gamma-ray burst spectrum formation based on this idea. This model allows the
GRB radiation to be optically thick and to have higher values of baryon load.
Thus the latter is limited by the energy considerations only, and not by the
condition of a small optical depth.

5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol