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

TL;DR

This study uses JWST, SMA, and Chandra to reexamine the fate of the proposed failed supernova M31-2014-DS1. The JWST data reveal a luminous mid-infrared source coincident with DS1, embedded in an asymmetric, dust-enshrouded environment, while X-ray and radio observations yield stringent non-detections. A 1-D DUSTY radiative transfer analysis cannot fit the full spectral energy distribution with a single shell, requiring a two-component model and implying a lower-limit bolometric luminosity of $\log(L/L_\odot)=3.85$; the dust geometry suggests that much of the intrinsic radiation may escape unprocessed, biasing luminosity estimates downward. Overall, the observations do not unambiguously support a classical failed SN or a simple merger scenario; instead, they point to either a heavily obscured, possibly BH-forming event or a stellar merger with unusual dust geometry, underscoring the need for continued JWST monitoring to distinguish between these possibilities.

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.

Figures (4)

• Figure 1: Top left: Finder chart for M31-2014-DS1 using Pan-starrs gri photometry. Top Right: JWST/MIRI imaging of the source remaining at the position of M31-2014-DS1. Bottom: PSFs in each JWST MIRI filter.
• Figure 2: The SED of the remaining source at the position of M31-2014-DS1 obserevd by JWST and SMA. The NIRSpec data have been smoothed using a moving average with a window size of 5 pixels (black solid line). We also show the SED of the progenitor star (green triangles) as well as post-outburst data (orange triangle).
• Figure 3: Comparison between the mid-IR appearance of M31-2014-DS1 and luminous red nova M31-LRN-2015 karambelkar2025hot. The fluxes have been normalised for direct comparison.
• Figure 4: Fit to the JWST data with DUSTY modeling and an additional reddened component.