A deep search for the host galaxies of GRBs with no detected optical afterglow

¹ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
² Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain
³ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
⁴ Department of Physics and Astronomy, Dickinson College, Carlisle, PA 17013, USA
⁵ Dark Cosmology Centre, Niels Bohr Institute, Univ. of Copenhagen, Juliane Maries Vej 30, 2100 Købnhaven, Denmark

Abstract

Long gamma-ray bursts (GRBs) pinpoint star-forming galaxies as they are linked to the deaths of massive stars. In most cases, these galaxies have been found to be blue, sub-luminous and of low-metallicity. However, our recent survey have demonstrated that a sizeable fraction of GRBs reside in massive, dusty and star-forming extremely red objects (EROs, (R − K)_AB > 3.5). The most remarkable case is the host of GRB 080207, one of the reddest galaxies ever associated with a GRB. This discovery suggests that at least a fraction of GRB afterglows trace a subpopulation of massive starburst galaxies, which are markedly different from the most studied blue, sub-luminous and compact GRB host galaxies.