A Multiwavelength Autopsy of the Interacting IIn Supernova 2020ywx: Tracing its Progenitor Mass-Loss History for 100 Years before Death

TL;DR

This study presents a comprehensive multiwavelength analysis of supernova SN 2020ywx, revealing its progenitor's prolonged mass-loss history over a century, likely driven by binary interaction, and highlighting CSM asymmetries and dust formation.

Contribution

It provides the first detailed multiwavelength modeling of SN 2020ywx, linking its mass-loss history to binary interaction and revealing CSM asymmetries and dust formation processes.

Findings

Progenitor lost mass at 10^{-2}--10^{-3} M_sun/yr for over 100 years.

Discrepancies between X-ray and optical/radio data suggest CSM asymmetries.

Evidence of dust formation with ~1000 K blackbody emission.

Abstract

While the subclass of interacting supernovae with narrow hydrogen emission lines (SNe IIn) consists of some of the longest-lasting and brightest SNe ever discovered, their progenitors are still not well understood. Investigating SNe IIn as they emit across the electromagnetic spectrum is the most robust way to understand the progenitor evolution before the explosion. This work presents X-Ray, optical, infrared, and radio observations of the strongly interacting Type IIn SN 2020ywx covering a period $>1200$ days after discovery. Through multiwavelength modeling, we find that the progenitor of 2020ywx was losing mass at $\sim10^{-2}$--$10^{-3} \mathrm{\,M_{\odot}\,yr^{-1}}$ for at least 100 yrs pre-explosion using the circumstellar medium (CSM) speed of 120 km/s measured from our optical and NIR spectra. Despite the similar magnitude of mass loss measured in different wavelength ranges, we find discrepancies between the X-ray and optical/radio-derived mass-loss evolution, which suggest asymmetries in the CSM. Furthermore, we find evidence for dust formation due to the combination of a growing blueshift in optical emission lines and near-infrared continuum emission which we fit with blackbodies at $\sim$ 1000 K. Based on the observed elevated mass loss over more than 100 years and the configuration of the CSM inferred from the multiwavelength observations, we invoke binary interaction as the most plausible mechanism to explain the overall mass-loss evolution. SN 2020ywx is thus a case that may support the growing observational consensus that SNe IIn mass loss is explained by binary interaction.