Gone without a bang: an archival HST survey for disappearing massive stars

Abstract

<p> It has been argued that a substantial fraction of massive stars may end their lives without an optically bright supernova (SN), but rather collapse to form a black hole. Such an event would not be detected by current SN surveys, which are focused on finding bright transients. Kochanek et&nbsp;al. proposed a novel survey for such events, using repeated observations of nearby galaxies to search for the disappearance of a massive star. We present such a survey, using the first systematic analysis of archival <em>Hubble Space Telescope</em> images of nearby galaxies with the aim of identifying evolved massive stars which have disappeared, <em>without</em> an accompanying optically bright SN. We consider a sample of 15 galaxies, with at least three epochs of <em>Hubble Space Telescope</em> imaging taken between 1994 and 2013. Within this data, we find one candidate which is consistent with a 25&ndash;30&nbsp;M_⊙ yellow supergiant which has undergone an optically dark core-collapse.</p>