The fate of the failed supernova candidate M31-2014-DS1

TL;DR

This study investigates the fate of a candidate failed supernova, M31-2014-DS1, using multi-wavelength observations, revealing a dust-enshrouded star with no X-ray emission, challenging the failed supernova hypothesis.

Contribution

The paper presents new JWST, SMA, and Chandra observations of M31-2014-DS1, providing insights into its dust-enshrouded nature and implications for failed supernova models.

Findings

Persistent mid-infrared source a decade after optical fading

No X-ray emission detected, arguing against black hole accretion

Highly asymmetric dust distribution complicates physical modeling

Abstract

The fate of massive stars above 20M$_{\odot}$ remains uncertain. Debate persists about whether they die as supernovae (SNe), or if they collapse directly into black holes (BHs) with little or no optical outburst -- so-called ``failed supernovae''. The source M31-2014-DS1 experienced an optical outburst in 2014 and has remained faint at visual wavelengths since then. Due to its persistent faintness, it has been proposed as a failed SN candidate. We present new observations of this candidate obtained using the James Webb Space Telescope (JWST), the Submillimeter Array (SMA), and Chandra. The JWST observations demonstrate that a luminous mid-infrared source persists at the same location a decade after the star faded at visual wavelengths. We model its current spectral energy distribution (SED) as a dust-enshrouded star. No X-ray emission is detected, disfavoring the hypothesis that the late-time luminosity is powered by accretion onto a BH. We find that the remaining source is highly obscured by an asymmetric distribution of circumstellar dust, making it difficult to quantify its physical properties using spherically symmetric radiative transfer codes. The dust geometry requires that the inferred bolometric luminosity is only a lower limit, as a significant fraction of the central source's radiation may escape without being reprocessed by dust. We discuss the implications of these findings in the context of failed SN models and consider the potential overlap with signatures expected from a stellar merger, which also seems to provide a plausible explanation of this source.