Hubble Space Telescope Deep Upper Limits Rule out a Surviving Massive Binary Companion to the Type Ic Supernova 2012fh

Abstract Current explanations of the mass-loss mechanism for stripped-envelope supernovae (SNe) remain divided between single and binary progenitor systems. Here we obtain deep ultraviolet (UV) imaging with the Hubble Space Telescope (HST) of the Type Ic SN 2012fh to search for the presence of a surviving companion star to the progenitor. We synthesize these observations with archival HST imaging, ground-based spectroscopy, and previous analyses from the literature to provide three independent constraints on the progenitor system. We fit the color–magnitude diagram of the surrounding population to constrain the most likely age of the system to be &lt;20 Myr. Analysis of spectra of SN 2012fh provides an estimate of the He core mass of the progenitor star, &gt;5.6 M ⊙ . We analyze deep HST images at the precise location after the SN faded to constrain the luminosity of any remaining main-sequence binary companion to be <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>L</mml:mi> <mml:mo>/</mml:mo> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> <mml:mo>≲</mml:mo> <mml:mn>3.35</mml:mn> </mml:math> . Combining observational constraints with current binary population synthesis models excludes the presence of a faint stellar companion to SN 2012fh at the ≲10% level. The progenitor was therefore either effectively isolated at the time of explosion or orbited by a black-hole companion. The latter scenario dominates if we only consider models that produce successful SNe.