SN 2023zaw: An Ultrastripped, Nickel-poor Supernova from a Low-mass Progenitor

July 2024 • 2024ApJ...969L..11D

Authors • Das, Kaustav K. • Fremling, Christoffer • Kasliwal, Mansi M. • Schulze, Steve • Sollerman, Jesper • Karambelkar, Viraj • Rose, Sam • Anand, Shreya • Andreoni, Igor • Aubert, Marie • Brennan, Sean J. • Cenko, S. Bradley • Coughlin, Michael W. • O'Connor, B. • De, Kishalay • Fuller, Jim • Graham, Matthew • Hammerstein, Erica • Haynie, Annastasia • Hinds, K. -Ryan • Kleiser, Io • Kulkarni, S. R. • Lin, Zeren • Liu, Chang • Mahabal, Ashish A. • Martin, Christopher • Miller, Adam A. • Neill, James D. • Perley, Daniel A. • Pessi, Priscila J. • Prusinski, Nikolaus Z. • Purdum, Josiah • Ravi, Vikram • Rusholme, Ben • Wu, Samantha • Wold, Avery • Yan, Lin

Abstract • We present SN 2023zaw—a subluminous (M _r = ‑16.7 mag) and rapidly evolving supernova (t _1/2,r = 4.9 days), with the lowest nickel mass (≈0.002 M _⊙) measured among all stripped-envelope supernovae discovered to date. The photospheric spectra are dominated by broad He I and Ca near-infrared emission lines with velocities of ∼10,000‑12,000 km s^‑1. The late-time spectra show prominent narrow He I emission lines at ∼1000 km s^‑1, indicative of interaction with He-rich circumstellar material. SN 2023zaw is located in the spiral arm of a star-forming galaxy. We perform radiation-hydrodynamical and analytical modeling of the lightcurve by fitting with a combination of shock-cooling emission and nickel decay. The progenitor has a best-fit envelope mass of ≈0.2 M _☉ and an envelope radius of ≈50 R _⊙. The extremely low nickel mass and low ejecta mass (≈0.5 M _⊙) suggest an ultrastripped SN, which originates from a mass-losing low-mass He-star (zero-age main-sequence mass < 10 M _⊙) in a close binary system. This is a channel to form double neutron star systems, whose merger is detectable with LIGO. SN 2023zaw underscores the existence of a previously undiscovered population of extremely low nickel mass (<0.005 M _☉) stripped-envelope supernovae, which can be explored with deep and high-cadence transient surveys.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2024ApJ...969L..11D
• PDF https://iopscience.iop.org/article/10.3847/2041-8213/ad527a/pdf
• PREPRINT http://arxiv.org/abs/2403.08165
• ELECTR https://doi.org/10.3847%2F2041-8213%2Fad527a