Host-Galaxy Properties of 32 Low-Redshift Superluminous Supernovae from the Palomar Transient Factory

TL;DR

This study analyzes the properties of host galaxies of 32 low-redshift superluminous supernovae, revealing that hydrogen-poor SLSNe predominantly occur in low-mass, metal-poor galaxies, while hydrogen-rich SLSNe are more broadly distributed.

Contribution

First comprehensive analysis of host galaxy properties for all SLSNe discovered by the Palomar Transient Factory before 2013, highlighting environmental dependencies of different SLSN types.

Findings

Type I SLSNe are mostly in low-mass, metal-poor galaxies.

SLSNe-I rate is suppressed in galaxies with metallicities >0.5 Z_sun.

Type II SLSNe occur across a wide range of galaxy properties.

Abstract

We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (SLSNe) discovered by the Palomar Transient Factory prior to 2013, and derive measurements of their luminosities, star-formation rates, stellar masses, and gas-phase metallicities. We find that Type I (hydrogen-poor) SLSNe are found almost exclusively in low-mass (M < 2x10^9 M_sun) and metal-poor (12+log[O/H] < 8.4) galaxies. We compare the mass and metallicity distributions of our sample to nearby galaxy catalogs in detail and conclude that the rate of SLSNe-I as a fraction of all SNe is heavily suppressed in galaxies with metallicities >0.5 Z_sun. Extremely low metallicities are not required, and indeed provide no further increase in the relative SLSN rate. Several SLSN-I hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star-formation histories. Type-II (hydrogen-rich) SLSNe are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. Two hosts exhibit unusual properties: PTF 10uhf is a Type I SLSN in a massive, luminous infrared galaxy at redshift z=0.29, while PTF 10tpz is a Type II SLSN located in the nucleus of an early-type host at z=0.04.