The Luminous Type Ia Supernova 2022ilv and Its Early Excess Emission

Abstract We present observations and analysis of the hostless luminous Type Ia supernova 2022ilv, illustrating it is part 2003fg-like family, often referred to as super-Chandrasekhar (Ia-SC) explosions. The Asteroid Terrestrial-impact Last Alert System light curve shows evidence a short-lived, pulse-like early excess, similar that detected in another (SN 2020hvf). broad, spectra are remarkably those SN 2009dc. Adopting redshift z = 0.026 ± 0.005 for 2022ilv based on spectral matching, our model requires large 56 Ni mass range 0.7–1.5 M ⊙ ejecta 1.6–2.3 . excess can be explained by fast-moving interacting with thin, dense shell circumstellar material close progenitor (∼10 13 cm) few hours after explosion. This may realized double-degenerate scenario, wherein white dwarf merger preceded ejection small amount −3 –10 −2 ) hydrogen helium-poor tidally stripped material. A deep pre-explosion Pan-STARRS1 stack indicates no host galaxy limiting magnitude r ∼ 24.5. implies surprisingly faint limit any ≳ −11, providing further these types explosions occur predominantly low-metallicity environments.