PGIR 20eid (SN 2020qmp): A Type IIP Supernova at 15.6 Mpc discovered by the Palomar Gattini-IR survey

Abstract

Aims. We present a detailed analysis of SN 2020qmp, a nearby Type II-P core-collapse supernova (CCSN), discovered by the Palomar Gattini-IR (PGIR) survey in the galaxy UGC07125 (distance of ≈ 15.6 ± 4 Mpc). We illustrate how the multiwavelength study of this event helps our general understanding of stellar progenitors and circumstellar medium (CSM) interactions in CCSNe. We highlight the importance of near-infrared (NIR) surveys for early detections of SNe in dusty environments. Methods. We analyze data from observations in various bands: radio, NIR, optical and X-rays. We use optical and NIR data for a spectroscopic and spectro-polarimetric study of the SN, and to model its lightcurve (LC). We estimate the explosion energy and zero-age main sequence (ZAMS) progenitor mass through hydrodynamical LC modeling. We also obtain an independent estimate of the ZAMS progenitor mass from the luminosity of the [O I] doublet lines (λλ6300, 6364) normalized to the decay power of 56 Co. From radio and X-ray observations, we derive the mass loss rate and microphysical parameters of the progenitor star, and investigate possible deviations from energy equipartition of magnetic fields and electrons in a standard CSM interaction model. Finally, we simulate a sample of CCSNe with plausible distributions of brightness and extinction, within 40 Mpc, and test what fraction of the sample is detectable at peak light by NIR surveys versus optical surveys. Results. SN 2020qmp displays characteristic hydrogen lines in its optical spectra, as well as a plateau in its optical LC, hallmarks of a Type II-P SN. We do not detect linear polarization during the plateau phase, with a 3σ upper limit of 0.78%. Through hydrodynamical LC modeling and an analysis of its nebular spectra, we estimate a progenitor mass of around 12 M , and an explosion energy of around 0.5 × 10 51 erg. We find that the spectral energy distribution cannot be explained by a simple CSM interaction model, assuming a constant shock velocity and steady mass-loss rate. In particular, the excess X-ray luminosity compared with the synchrotron radio luminosity suggests deviations from equipartition. Finally, we demonstrate the advantages of NIR surveys over optical surveys for the detection of dust-obscured CCSNe in the local universe. Specifically, our simulations show that the Wide-Field Infrared Transient Explorer (WINTER) will detect about 14 more CCSNe out of 75 expected in its footprint within 40 Mpc, over five years than an optical survey equivalent to the Zwicky Transient Facility (ZTF) would detect. Conclusions. We have determined or constrained the main properties of SN 2020qmp and of its progenitor, highlighting the value of multiwavelength follow up observations of nearby CCSNe. We have shown that forthcoming NIR surveys will finally enable us to do a nearly complete census of CCSNe in the local universe.