The Most Luminous Supernova to Date– Science magazine

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) × 10⁴⁵ 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) × 10⁵²ergs, challenging the magnetar model for its engine.

This supernova, at an estimated distance of 3.8 billion light years from us, is still a visible, superluminous supernova.  For four months, it has radiated energies that “challenge” the magnetar model– that is, the model of a central tiny, rapidly spinning magnetized core.  Its brightness is estimated at 570 billion times that of the sun (BBC story.)