SN 2023fyq: direct detection of a Type Ibn supernova progenitor and its multi-wavelength environmental constraints

TL;DR

This paper reports the first direct detection of a progenitor for a Type Ibn supernova, SN 2023fyq, using multi-wavelength imaging and spectroscopy, providing new insights into its progenitor's nature and environment.

Contribution

It identifies and characterizes the progenitor of SN 2023fyq, supporting a binary low-mass helium star scenario over a massive single star.

Findings

Progenitor is hot, luminous, and has disappeared post-explosion.

Environment analysis suggests a binary progenitor with an age of 10^7.1–7.2 years.

Disfavors very massive single-star progenitors for this supernova.

Abstract

Context. Type Ibn supernovae (SNe) are characterized by narrow helium emission lines arising from ejecta-circumstellar medium interaction, yet their progenitors remain debated, with both massive Wolf-Rayet stars and low-mass helium stars in binaries proposed. Aims. We aim to directly identify the progenitor of the Type Ibn SN 2023fyq and to characterize its environment in order to constrain the progenitor's nature and evolutionary channel. Methods. We search for the SN progenitor based on pre-explosion and late-time HST and JWST images and derive its properties by fitting the spectral energy distribution. We investigate the SN environment by probing the stars, dust, ionized gas and molecular gas with a multi-wavelength dataset including HST and JWST imaging, VLT/MUSE integral-field-unit spectroscopy and ALMA CO (2--1) radio interferometry. Results. We discover a pre-explosion source at the SN position, which is consistent with a hot ($T>$15000 K) and luminous (log($L$/$L_\odot$) $\gtrsim$ 5.5) SN progenitor and a possible host star cluster. The progenitor is confirmed to have disappeared after explosion. Analysis of the SN environment implies that the progenitor likely has an age of log($t$/yr) = 7.1--7.2. These phenomena disfavor a very massive single-star progenitor and instead support a binary scenario involving a low-mass helium star and a compact object; the observed progenitor emission likely arises from binary interaction that began at least $\sim$12 yr before the explosion. Conclusions. SN 2023fyq is the first Type Ibn SN with a directly detected progenitor and a possible host star cluster. It adds to the diversity of Type Ibn SNe in terms of their progenitor channels and mass-loss mechanisms.