Low-luminosity Type IIP Supernovae from the Zwicky Transient Facility Census of the Local Universe. I. Luminosity Function, Volumetric Rate

Year: 2025 DOI: 10.1088/1538-3873/adcaeb
We present the luminosity function and volumetric rate of a sample of Type IIP supernovae (SNe) from the Zwicky Transient Facility Census of the Local Universe survey (CLU). This is the largest sample of Type IIP SNe from a systematic volume-limited survey to-date. The final sample includes 330 Type IIP SNe and 36 low-luminosity Type II (LLIIP) SNe with Mr,peak > −16 mag, which triples the literature sample of LLIIP SNe. The fraction of LLIIP SNe is 19⁺³₋₄% of the total CLU Type IIP SNe population (8⁺¹₋₂% of all core-collapse SNe). This implies that while LLIIP SNe likely represent the fate of core-collapse SNe of 8–12 M⊙ progenitors, they alone cannot account for the fate of all massive stars in this mass range. To derive an absolute rate, we estimate the ZTF pipeline efficiency as a function of the apparent magnitude and the local surface brightness. We derive a volumetric rate of (3.9^(+0.4)_(−0.4)) × 10⁴ Gpc⁻³ yr⁻¹ for Type IIP SNe and (7.3^(+0.6)_(-0.6) x 10³ Gpc⁻³ yr⁻¹ for LLIIP SNe. Now that the rate of LLIIP SNe is robustly derived, the unresolved discrepancy between core-collapse SN rates and star formation rates cannot be explained by LLIIP SNe alone.