Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Swift Discovery of Gamma-Ray Bursts without Jet Break Feature in their
  X-Ray Afterglows   We analyze Swift gamma-ray bursts (GRBs) and X-ray afterglows for three GRBs
with spectroscopic redshift determinations -- GRB 050401, XRF 050416a, and GRB
050525a. We find that the relation between spectral peak energy and isotropic
energy of prompt emissions (the Amati relation) is consistent with that for the
bursts observed in pre-Swift era. However, we find that the X-ray afterglow
lightcurves, which extend up to 10-70 days, show no sign of the jet break that
is expected in the standard framework of collimated outflows. We do so by
showing that none of the X-ray afterglow lightcurves in our sample satisfies
the relation between the spectral and temporal indices that is predicted for
the phase after jet break. The jet break time can be predicted by inverting the
tight empirical relation between the peak energy of the spectrum and the
collimation-corrected energy of the prompt emission (the Ghirlanda relation).
We find that there are no temporal breaks within the predicted time intervals
in X-ray band. This requires either that the Ghirlanda relation has a larger
scatter than previously thought, that the temporal break in X-rays is masked by
some additional source of X-ray emission, or that it does not happen because of
some unknown reason.

3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex