Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraining the environment of GRB 990712 through emission line fluxes   The energy output in the gamma-ray burst (GRB) prompt emission and afterglow
phase is expected to photoionize the surrounding medium out to large radii.
Cooling of this gas produces line emission, particularly strong in the optical,
whose variability is a strong diagnostics of the gas density and geometry in
the close environment of the burst. We present the results of a spectral time
series analysis of the host galaxy of GRB 990712 observed up to ~6 years after
the burst. We analyze the emission line fluxes together with those of the
previous observations of the same GRB, in search for photoionization
signatures. We find that the emission line fluxes show no variation within the
uncertainities up to 6 years after the burst, and we use the measured line
intensities to set a limit on the density of the gas within a few parsecs of
the burst location. This is the first time that emission from cooling GRB
remnants is probed on years time scales.

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The categories of this paper are: cs
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The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
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The categories of this paper are: eess
26
The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th