# HST Deep Upper Limits Rule Out a Surviving Massive Binary Companion to the Type Ic Supernova 2012fh

## TL;DR

Deep UV imaging with HST rules out a surviving luminous binary companion to SN 2012fh, supporting the idea that its progenitor was either isolated or orbited by a black hole, influencing supernova progenitor models.

## Contribution

This study provides the first deep UV constraints on the presence of a binary companion to a Type Ic supernova, challenging previous binary progenitor hypotheses.

## Key findings

- No luminous companion detected at the supernova site.
- Progenitor likely isolated or with a black hole companion.
- Excludes faint stellar companions at less than 10% probability.

## Abstract

Current explanations of the mass-loss mechanism for stripped-envelope supernovae 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 $<20$ Myr. Analysis of spectra of SN 2012fh provide an estimate of the He core mass of the progenitor star, $>5.6$ M$_{\odot}$. 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 $\log(L/L_{\odot}) \lesssim 3.35$. Combining observational constraints with current binary population synthesis models excludes the presence of a faint stellar companion to SN 2012fh at the $\lesssim10\%$ 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 supernovae.