2021MNRAS.500.5142F

We present measurements of the local core-collapse supernova (CCSN) rate using SN discoveries from the Palomar Transient Factory (PTF). We use a Monte Carlo simulation of hundreds of millions of SN light-curve realizations coupled with the detailed PTF survey detection efficiencies to forward model the SN rates in PTF. Using a sample of 86 CCSNe, including 26 stripped-envelope SNe (SESNe), we show that the overall CCSN volumetric rate is r^CC_v=9.10_–1.27^+1.56×10^–5 SNe yr^–1 Mpc^–3 h₇₀³ at <z> = 0.028, and the SESN volumetric rate is r^SE_v=2.41_–0.64^+0.81×10^–5 SNe yr^–1 Mpc^–3 h₇₀³. We further measure a volumetric rate for hydrogen-free superluminous SNe (SLSNe-I) using eight events at z <= 0.2 of r^SLSN–I_v=35_–13⁺²⁵ SNe yr^–1Gpc^–3 h₇₀³, which represents the most precise SLSN-I rate measurement to date. Using a simple cosmic star formation history to adjust these volumetric rate measurements to the same redshift, we measure a local ratio of SLSN-I to SESN of ∼1/810⁺¹⁵⁰⁰_–94, and of SLSN-I to all CCSN types of ∼1/3500⁺²⁸⁰⁰_–720. However, using host galaxy stellar mass as a proxy for metallicity, we also show that this ratio is strongly metallicity dependent: in low-mass (logM_* < 9.5 M_☉) galaxies, which are the only environments that host SLSN-I in our sample, we measure an SLSN-I to SESN fraction of 1/300⁺³⁸⁰_–170 and 1/1700⁺¹⁸⁰⁰_–720 for all CCSN. We further investigate the SN rates a function of host galaxy stellar mass, and show that the specific rates of all CCSNe decrease with increasing stellar mass.