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arXiv · 0709.0198

The host galaxy of GRB031203: a new spectroscopic study

R. Margutti·G. Chincarini·S. Covino·G. Tagliaferri·S. Campana·M. Della Valle·A. V. Filippenko·F. Fiore·R. Foley·D. Fugazza·P. Giommi·D. Malesani·A. Moretti·L. Stella
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Abstract

The host galaxy of the long-duration gamma-ray burst (GRB) 031203 (HG031203) offers a precious opportunity to study in detail the environment of a nearby GRB. The aim is to better characterize this galaxy and analyse the possible evolution with time of the spectroscopic quantities we derive. We analyse HG031203 using a set of optical spectra acquired with the ESO-VLT and Keck telescope. We compare the metallicity, luminosity and star formation properties of this galaxy and of the other supernova-long gamma-ray burst hosts in the local universe (z<0.2) against the KPNO International Spectroscopic Survey. HG031203 is a metal poor, actively star forming galaxy (star formation rate of 12.9+/-2.2 {M_{sun} yr^-1) at z=0.1054. From the emission-line analysis we derive an intrinsic reddening E_{HG}(B-V)\approx 0.4. This parameter doesn't show a compelling evidence of evolution at a month time-scale. We find an interstellar medium temperature of 12500 K and an electronic density of N_{e}=160 cm^-3. After investigating for possible Wolf-Rayet emission features in our spectra, we consider dubious the classification of HG031203 as a Wolf-Rayet galaxy. Long gamma-ray burst (LGRB) and supernova hosts in the local universe (z<0.2) show, on average, specific star formation rates higher than ordinary star forming galaxy at the same redshift. On the other hand, we find that half of the hosts follows the metallicity-luminosity relation found for star-burst galaxies; HG031203 is a clear outlier, with its really low metallicity (12+\log{O/H}=8.12+/-0.04).

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R. Margutti, G. Chincarini, S. Covino, G. Tagliaferri, S. Campana, M. Della Valle, A. V. Filippenko, F. Fiore, R. Foley, D. Fugazza, P. Giommi, D. Malesani, A. Moretti, L. Stella. 2007-09-06. The host galaxy of GRB031203: a new spectroscopic study. https://doi.org/10.1051/0004-6361:20077698

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