Superluminous Supernovae

Abstract

Superluminous supernovae are hydrogen-rich (SLSNe-II), or hydrogen-poor (SLSNe-I), explosions so bright that they require a power source beyond that of traditional supernovae. SLSNe-I rise to a peak over 20–90 days and then decline over a timescale roughly twice as long. At early times they have a blue continuum, peaking in the ultraviolet, have temperatures in excess of 14,000 K, and show ionized lines of carbon and oxygen out of thermodynamic equilibrium. As the supernovae cool, their spectra start to resemble SNe Ic, though with a time delay. They also favor environments with metallicities half solar or lower. Modeling indicates that they are explosions of stripped carbon-oxygen stellar cores, similar to but sometimes more massive than the progenitors of SNe Ic. SLSNe-I similar to SN 2007bi have broader light curves and seemingly more massive progenitors. Some have proposed that these are pair-instability supernovae, but in general the supernovae rise too quickly for this model. Most SLSNe-I show no signs of interaction and instead seem to be powered by a central engine. The magnetar spin-down model has been the most successful at reproducing the light curves and peak luminosity of SLSNe, though it may not be unique. Most SLSNe-II seem to be powered by interaction of these SNe with circumstellar material, as in SNe IIn. However, there are a handful of hybrid cases, or SLSNe-II, with weak or little interaction, which may be related to SLSNe-I.