2022/10/05 by I. Irani, Ping Chen, Irani, I. +55
Physics and Astronomy · #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2210.02554
openalex publication_date 2022/10/05 · openalex created_date 2022/10/08 · openalex updated_date 2026/07/28
We present the discovery and analysis of SN 2022oqm, a Type Ic supernova (SN) detected <1 day after explosion. The SN rises to a blue and short-lived (2 days) initial peak. Early-time spectral observations of SN 2022oqm show a hot (40,000 K) continuum with high-ionization C and O absorption features at velocities of 4000 km s-1, while its photospheric radius expands at 20,000 \kms, indicating a pre-existing distribution of expanding C/O material. After ∼2.5 days, both the spectrum and light curves evolve into those of a typical SN Ic, with line velocities of ∼10,000 km s-1, in agreement with the photospheric radius evolution. The optical light curves reach a second peak at t≈15 days. By t=60 days, the spectrum of \oqm becomes nearly nebular, displaying strong \ionCa2 and [\ionCa2] emission with no detectable [\ionO1], marking this event as Ca-rich. The early behavior can be explained by 10-3 \msun of optically thin circumstellar material (CSM) surrounding either (1) a massive compact progenitor such as a Wolf-Rayet star, (2) a massive stripped progenitor with an extended envelope, or (3) a binary system with a white dwarf. We propose that the early-time light curve is powered by both interaction of the ejecta with the optically thin CSM and shock cooling (in the massive-star scenario). The observations can be explained by CSM that is optically thick to X-ray photons, is optically thick in the lines as seen in the spectra, and is optically thin to visible-light continuum photons that come either from downscattered X-rays or from the shock-heated ejecta. Calculations show that this scenario is self-consistent.