We present UBVRIZJsHKs broad band photometry of the host galaxy of the dark gamma-ray burst (GRB) of February 10, 2000. These observations represent the most exhaustive photometry given to date of any GRB host galaxy. A grid of spectral templates have been fitted to the Spectral Energy Distribution (SED) of the host. The derived photometric redshift is z=0.842+0.054-0.042, which is in excellent agreement with the spectroscopic redshift (z=0.8463± 0.0002) proposed by Piro et al. (\cite{Piro02}) based on a single emission line. Furthermore, we have determined the photometric redshift of all the galaxies in an area of 6' × 6' around the host galaxy, in order to check for their overdensity in the environment of the host. We find that the GRB 000210 host galaxy is a subluminous galaxy (L ˜ 0.5 ± 0.2 L*), with no companions above our detection threshold of 0.18 ± 0.06 L*. Based on the restframe ultraviolet flux a star formation rate of 2.1 ± 0.2 Msun yr-1 is estimated. The best fit to the SED is obtained for a starburst template with an age of 0.181+0.037-0.026 Gyr and a very low extinction (AV ˜ 0). We discuss the implications of the inferred low value of AV and the age of the dominant stellar population for the non-detection of the GRB 000210 optical afterglow. Based on observations collected at the European Southern Observatory, in La Silla and Paranal (Chile), ESO Large Programmes 165.H-0464(E), 165.H-0464(I) and 265.D-5742(C), granted to the GRACE Team. Based on observations made with the Danish 1.54-m telescope, in La Silla (Chile).
A multi-colour study of the dark GRB 000210 host galaxy and its environment
FRONTERA, Filippo;
2003
Abstract
We present UBVRIZJsHKs broad band photometry of the host galaxy of the dark gamma-ray burst (GRB) of February 10, 2000. These observations represent the most exhaustive photometry given to date of any GRB host galaxy. A grid of spectral templates have been fitted to the Spectral Energy Distribution (SED) of the host. The derived photometric redshift is z=0.842+0.054-0.042, which is in excellent agreement with the spectroscopic redshift (z=0.8463± 0.0002) proposed by Piro et al. (\cite{Piro02}) based on a single emission line. Furthermore, we have determined the photometric redshift of all the galaxies in an area of 6' × 6' around the host galaxy, in order to check for their overdensity in the environment of the host. We find that the GRB 000210 host galaxy is a subluminous galaxy (L ˜ 0.5 ± 0.2 L*), with no companions above our detection threshold of 0.18 ± 0.06 L*. Based on the restframe ultraviolet flux a star formation rate of 2.1 ± 0.2 Msun yr-1 is estimated. The best fit to the SED is obtained for a starburst template with an age of 0.181+0.037-0.026 Gyr and a very low extinction (AV ˜ 0). We discuss the implications of the inferred low value of AV and the age of the dominant stellar population for the non-detection of the GRB 000210 optical afterglow. Based on observations collected at the European Southern Observatory, in La Silla and Paranal (Chile), ESO Large Programmes 165.H-0464(E), 165.H-0464(I) and 265.D-5742(C), granted to the GRACE Team. Based on observations made with the Danish 1.54-m telescope, in La Silla (Chile).I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
