The host galaxy of GRB 031203: a new spectroscopic study

\n Aims.The host galaxy of the long-duration gamma-ray burst (GRB) 031203 \n(HG 031203) offers a precious opportunity to study in detail the \nenvironment of a nearby GRB. The aim is to \nbetter characterize this galaxy and analyse the \npossible evolution with time of the spectroscopic quantities we derive.\n\n Methods.We analyse HG 031203 using a set of optical spectra acquired with \nthe ESO-VLT and Keck telescope. We compare the metallicity, luminosity and star\nformation properties of this galaxy and of the other supernova-long gamma-ray burst hosts in the local universe ($z < 0.2$)\nagainst the KPNO International Spectroscopic Survey. \n Results.\nHG 031203 is a metal poor, actively star forming\ngalaxy (star formation rate of 12.9±2.2 $ M_{\\odot}$ yr-1) at $z = 0.1054$.\nFrom the emission-line analysis we derive an intrinsic reddening $E_{\\mathrm{HG}}(B-V)$ ≈ 0.4. \nThis parameter doesn't show a compelling evidence of evolution at a month time-scale. \nWe find an interstellar medium\ntemperature of ≈ 12 500 K and an electronic density of $N_{\\mathrm{e}}$ = 160 cm-3. \nAfter investigating for possible Wolf-Rayet emission features in our spectra,\nwe consider dubious the classification of HG 031203 as a Wolf-Rayet galaxy.\nLong gamma-ray burst (LGRB) and supernova hosts in the local universe ($z < 0.2$) show, on average, specific\nstar formation rates higher than ordinary star forming galaxy at the same redshift.\nOn the other hand, we find that half of the hosts follows the metallicity–luminosity relation\nfound for star-burst galaxies;\nHG 031203 is a clear outlier, with its really low metallicity (12+log(O/H) = 8.12±0.04).\n \n