ASASSN-15lh: A Highly Super-Luminous Supernova

TL;DR

ASASSN-15lh is the most luminous supernova discovered, challenging existing models and showing unique host galaxy characteristics, with implications for understanding super-luminous supernovae energy sources.

Contribution

This paper reports the discovery and detailed analysis of ASASSN-15lh, the most luminous supernova, highlighting its unusual host galaxy and challenging the magnetar model for super-luminous supernovae.

Findings

Reaches an absolute magnitude of -23.5, more than twice as luminous as previous supernovae.

Hosted by a luminous galaxy with little star formation, unlike typical SLSNe-I hosts.

Radiated approximately 1.1x10^52 ergs in 4 months, challenging existing energy source models.

Abstract

We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as the most luminous supernova yet found. At redshift z = 0.2326, ASASSN-15lh reached an absolute magnitude of M_{u,AB} = -23.5+/-0.1 and bolometric luminosity L_bol = (2.2+/-0.2)x 10^45 ergs s^-1, which is more than twice as luminous as any previously known supernova. It has several major features characteristic of the hydrogen-poor super-luminous supernovae (SLSNe-I), whose energy sources and progenitors are currently poorly understood. In contrast to most previously known SLSNe-I that reside in star-forming dwarf galaxies, ASASSN-15lh appears to be hosted by a luminous galaxy (M_K ~ -25.5) with little star formation. In the 4 months since first detection, ASASSN-15lh radiated (1.1+/- 0.2)x10^52 ergs, challenging the magnetar model for its engine.