This Letter presents the detection of a source at the position of the Type Ib/c supernova (SN) 2013ge more than four years after the radioactive component is expected to have faded. This source could mark the first post-SN direct detection of a surviving companion to a stripped-envelope Type Ib/c explosion. We test this hypothesis and find the shape of the source's spectral energy distribution is most consistent with that of a B5 I supergiant. While binary models tend to predict OB-type stars for stripped-envelope companions, the location of the source on a color-magnitude diagram places it redward of its more likely position on the main sequence (MS). The source may be temporarily out of thermal equilibrium, or a cool and inflated non-MS companion, which is similar to the suggested companion of Type Ib SN 2019yvr that was constrained from pre-SN imaging. We also consider other possible physical scenarios for the source, including a fading SN, circumstellar shock interaction, line-of-sight coincidence, and an unresolved host star cluster, all of which will require future observations to more definitively rule out. Ultimately, the fraction of surviving companions ("binary fraction") will provide necessary constraints on binary evolution models and the underlying physics.
Bibliographical noteFunding Information:
This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. These observations are associated with programs GO-16165 (PI O. Fox), GO-15166 (PI A. Filippenko), GO-14762 (PI J. Maund), and GO-14668 (PI A. Filippenko); we are also grateful for the associated funding from NASA/STScI. O.D.F. would like to thank Karl Gordon for useful conversations on dust. E.Z. acknowledges support from the Swiss National Science Foundation Professorship grant (project PP00P2 176868; PI Tassos Fragos). M.R.D. acknowledges support from the NSERC through grant RGPIN-2019-06186, the Canada Research Chairs Program, the Canadian Institute for Advanced Research (CIFAR), and the Dunlap Institute at the University of Toronto. In addition to the NASA/STScI funding, A.V.F. received support from the Miller Institute for Basic Research in Science (where he was a Miller Senior Fellow) and the Christopher R. Redlich Fund. D.M. acknowledges NSF support from grants PHY-1914448 and AST-2037297.
© 2022. The Author(s). Published by the American Astronomical Society.