GRB 091127/SN 2009nz and the VLT/X-shooter spectroscopy of its host galaxy: probing the faint end of the mass-metallicity relation
Covino, S.; D'Avanzo, P.; Sánchez-Ramírez, R.; Campana, S.; Tagliaferri, G.; Antonelli, L. A.; Ghirlanda, G.; Melandri, A.; Salvaterra, R.; D'Elia, V.; Fugazza, D.; Palazzi, E.; Sollerman, J.; Goldoni, P.; Kaper, L.; Wijers, R. A. M. J.; Milvang-Jensen, B.; Fynbo, J. P. U.; Gorosabel, J.; Wiersema, K.; Castro-Tirado, A. J.; Jelínek, M.; Levan, A. J.; Tanvir, N. R.; Malesani, D.; Vergani, S. D.; Flores, H.; Hjorth, J.; Jakobsson, P.; Thöne, C. C.; de Ugarte Postigo, A.; Hammer, F.; Puech, M.; Piranomonte, S.; Fernández, M.; Rodrigues, M.; Tello, J. C.; Lundgren, A.; Terrón, V.
Italy, France, Spain, United Kingdom, Denmark, Chile, Iceland, Netherlands, Sweden
Abstract
We perform a detailed study of the gamma-ray burst GRB 091127/SN 2009nz host galaxy at z = 0.490 using the VLT/X-shooter spectrograph in slit and integral-field unit (IFU) mode. From the analysis of the optical and X-ray afterglow data obtained from ground-based telescopes and Swift-XRT, we confirm the presence of a bump associated with SN 2009nz and find evidence of a possible jet break in the afterglow lightcurve. The X-shooter afterglow spectra reveal several emission lines from the underlying host, from which we derive its integrated properties. These properties agree with those of previously studied GRB-SN hosts and, more generally, with those of the long GRB host population. We use the Hubble Space Telescope and ground-based images of the host to determine its stellar mass (M⋆). Our results extend to lower M⋆ values the M-Z plot derived for the sample of long GRB hosts at 0.3 < z < 1.0 adding new information to probe the faint end of the M-Z relation and the shift of the LGRB host M-Z relation from that found from emission-line galaxy surveys. Thanks to the IFU spectroscopy, we can build the two-dimensional (2D) velocity, velocity dispersion, and star formation rate (SFR) maps. They show that the host galaxy has perturbed rotation kinematics with evidence of a SFR enhancement consistent with the afterglow position.
Based on observations made with ESO Telescopes at Paranal Observatory under programmes ID 084.A-0260 and 086.A-0874.