Supernova rates and luminosity functions from ASAS-SN

Abstract

Aims. The volumetric rates and luminosity functions (LFs) of core-collapse supernovae (ccSN) and their subtypes are important for understanding the cosmic history of star formation and the buildup of ccSNe products. To estimate these rates, we used data of nearby ccSNe discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN) from 2014 to 2017, when all observations were made in the V band. Methods. The sample is composed of 174 discovered or recovered events, with high spectroscopic completeness from follow-up observations. This allowed us to obtain a statistically precise and systematically robust estimate of nearby rates for ccSNe and their subtypes. The volumetric rates were estimated by correcting the observed number of events for survey completeness, which was estimated through injection recovery simulations using ccSN light curves. Results. We find a total volumetric rate for ccSNe of 7.0 +1.0 −0.9 × 10 −5 yr −1 Mpc −3 h 3 70 , at a median redshift of 0.0149, for absolute magnitudes at peak M V , peak ≤ −14 mag. This result is in agreement with previous local volumetric rates. We obtain volumetric rates for the different ccSN subtypes (II, IIn, IIb, Ib, Ic, Ibn, and Ic-BL), and find that the relative fractions of Type II, stripped-envelope, and interacting ccSNe are 63.2%, 32.3%, and 4.4%, respectively. We also estimate a volumetric rate for superluminous SNe of 1.5 +4.4 −1.1 yr −1 Gpc −3 h 3 70 , corresponding to a fraction of 0.002% of the total ccSN rate. We produced intrinsic V -band LFs of ccSNe and their subtypes, and show that ccSN rates steadily decline for increasing luminosities. We further investigated the specific ccSN rate as a function of their host galaxy stellar mass and find that the rate decreases with increasing stellar mass, with significantly higher rates at lower mass galaxies (log M * < 9.0 M ⊙ ).

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