The Highly Luminous Type Ibn Supernova ASASSN-14ms

TL;DR

This paper reports detailed observations of ASASSN-14ms, one of the most luminous Type Ibn supernovae, analyzing its brightness, spectra, and host galaxy to understand its power sources and environment.

Contribution

It provides comprehensive photometric and spectroscopic data on ASASSN-14ms, highlighting its extreme luminosity and suggesting combined radioactive decay and circumstellar interaction as power sources.

Findings

ASASSN-14ms is among the most luminous Type Ibn supernovae.

The supernova's spectra show signs of dense circumstellar medium.

Host galaxy has low metallicity and low star formation rate.

Abstract

We present photometric and spectroscopic follow-up observations of the highly luminous Type Ibn supernova ASASSN-14ms, which was discovered on UT 2014-12-26.61 at $m_V \sim 16.5$. With a peak absolute $V$-band magnitude brighter than $-20.5$, a peak bolometric luminosity of $1.7 \times 10^{44}$ ergs s$^{-1}$, and a total radiated energy of $2.1 \times 10^{50}$ ergs, ASASSN-14ms is one of the most luminous Type Ibn supernovae yet discovered. In simple models, the most likely power source for this event is a combination of the radioactive decay of $^{56}$Ni and $^{56}$Co at late times and the interaction of supernova ejecta with the progenitor's circumstellar medium at early times, although we cannot rule out the possibility of a magnetar-powered light curve. The presence of a dense circumstellar medium is indicated by the intermediate-width He I features in the spectra. The faint ($m_g \sim 21.6$) host galaxy SDSS J130408.52+521846.4 has an oxygen abundance below $12+\log(O/H) \lesssim 8.3$, a stellar mass of $M_* \sim 2.6 \times 10^8 M_{\odot}$, and a star formation rate of $\textrm{SFR} \sim 0.02$ $M_{\odot}$ yr$^{-1}$.