Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A nearby GRB host prototype for z~7 Lyman-break galaxies: Spitzer-IRS
  and X-shooter spectroscopy of the host galaxy of GRB031203   Gamma-ray burst (GRB) host galaxies have been studied extensively in optical
photometry and spectroscopy. Here we present the first mid-infrared spectrum of
a GRB host, HG031203. It is one of the nearest GRB hosts at z=0.1055, allowing
both low and high-resolution spectroscopy with Spitzer-IRS. Medium resolution
UV-to-K-band spectroscopy with the X-shooter spectrograph on the VLT is also
presented, along with Spitzer IRAC and MIPS photometry, as well as radio and
sub-mm observations. These data allow us to construct a UV-to-radio spectral
energy distribution with almost complete spectroscopic coverage from 0.3-35
micron of a GRB host galaxy for the first time, potentially valuable as a
template for future model comparisons. The IRS spectra show strong,
high-ionisation fine structure line emission indicative of a hard radiation
field in the galaxy, suggestive of strong ongoing star-formation and a very
young stellar population. The selection of HG031203 via the presence of a GRB
suggests that it might be a useful analogue of very young star-forming galaxies
in the early universe, and hints that local BCDs may be used as more reliable
analogues of star-formation in the early universe than typical local
starbursts. We look at the current debate on the ages of the dominant stellar
populations in z~7 and z~8 galaxies in this context. The nebular line emission
is so strong in HG031203, that at z~7, it can reproduce the spectral energy
distributions of z-band dropout galaxies with elevated IRAC 3.6 and 4.5 micron
fluxes without the need to invoke a 4000A break.

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The categories of this paper are: q-bio
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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: math
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The categories of this paper are: gr-qc
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys