2019MNRAS.484L..79G

Type Ia supernovae are understood to arise from the thermonuclear explosion of a carbon-oxygen white dwarf, yet the evolutionary mechanisms leading to such events remain unknown. Many proposed channels, including the classical single-degenerate scenario, invoke a hot, luminous evolutionary phase for the progenitor, in which it is a prodigious source of photoionizing emission. Here, we examine the environment of SN 2014J for evidence of a photoionized nebula in pre- and post-explosion [O III] λ5007 Å and H β images taken with the Hubble Space Telescope. From the absence of any extended emission, we exclude a stable nuclear-burning white dwarf at the location of SN 2014J in the last ∼100 000 years, assuming a typical warm interstellar medium (ISM) particle density of 1 cm^–3. These limits greatly exceed existing X-ray constraints at temperatures typical of known supersoft sources. Significant extreme-UV/soft X-ray emission prior to explosion remains plausible for lower ISM densities (e.g. n_ ISM_∼0.1 cm^–3). In this case, however, any putative nebula would be even more extended, allowing deeper follow-up observations to resolve this ambiguity in the near future.