Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Swift observations of the prompt X-ray emission and afterglow from
  GRB050126 and GRB050219A   We report on the temporal and spectral characteristics of the early X-ray
emission from the Gamma Ray Bursts GRB050126 and GRB050219A as observed by
Swift. The X-ray light-curves of these 2 bursts both show remarkably steep
early decays (F(t)\propto t^{-3}), breaking to flatter slopes on timescales of
a few hundred seconds. For GRB050126 the burst shows no evidence of spectral
evolution in the 20-150 keV band, and the spectral index of the gamma-ray and
X-ray afterglows are significantly different suggesting a separate origin. By
contrast the BAT spectrum of GRB050219A displays significant spectral
evolution, becoming softer at later times, with Gamma evolving toward the XRT
photon index seen in the early X-ray afterglow phase. For both bursts, the
0.2-10 keV spectral index pre- and post-break in the X-ray decay light-curve
are consistent with no spectral evolution. We suggest that the steep early
decline in the X-ray decay light-curve is either the curvature tail of the
prompt emission; X-ray flaring activity; or external forward shock emission
from a jet with high density regions of small angular size (> Gamma^{-1}). The
late slope we associate with the forward external shock.

3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th