Near-Infrared and Optical Observations of Type Ic SN2020oi and broad-lined Ic SN2020bvc: Carbon Monoxide, Dust and High-Velocity Supernova Ejecta

Abstract

We present near-infrared and optical observations of the Type Ic Supernova (SN) 2020oi in the galaxy M100 and the broad-lined Type Ic SN2020bvc in UGC 9379, using Gemini, LCO, SOAR, and other ground-based telescopes. The near-IR spectrum of SN2020oi at day 63 since the explosion shows strong CO emissions and a rising K-band continuum, which is the first unambiguous dust detection from a Type Ic SN. Non-LTE CO modeling shows that CO is still optically thick, and that the lower limit to the CO mass is 10 −3 M . The dust temperature is 810 K, and the dust mass is ∼10 −5 M . We explore the possibilities that the dust is freshly formed in the ejecta, heated dust in the pre-existing circumstellar medium, and an infrared echo. The light curves of SN2020oi are consistent with a STELLA model with canonical explosion energy, 0.07 M Ni mass, and 0.7 M ejecta mass. A model of high explosion energy of 10 52 erg, 0.4 M Ni mass, 6.5 M ejecta mass with the circumstellar matter, reproduces the double-peaked light curves of SN2020bvc. We observe temporal changes of absorption features of the IR Ca ii triplet, S i at 1.043 µm, and Fe ii at 5169 Å. The blue-shifted lines indicate high velocities, up to 60,000 km s −1 for SN2020bvc and 20,000 km s −1 for SN2020oi, and the expansion velocity rapidly declines before the optical maximum. We present spectral signatures and diagnostics of CO and SiO molecular bands between 1.4 and 10 µm.

The effect of circumstellar matter on the double-peaked type Ic supernovae and implications for LSQ14efd, iPTF15dtg and SN 2020bvc

“…For SN 2020bvc, we already presented a result of our model comparison with the observation in another paper (Rho et al 2020). For this particular SN, we use the 8P progenitor and assume that 56 Ni is uniformly distributed in the inner 90% of the SN ejecta.…”

“…The presence of massive CSM might also be responsible for the first peak of several double-peaked superluminous SNe Ic (e.g., LSQ14bdq; Nicholl et al 2015;Nicholl & Smartt 2016) and peculiar SNe Ic like SN 2006aj (e.g., Modjaz et al 2006), iPTF15dtg (Taddia et al 2016(Taddia et al , 2019 and SN 2020bvc (Ho et al 2020;Rho et al 2020). The magnetar scenario is often invoked to explain such an unusual SN Ic.…”

An Early-Time Optical and Ultraviolet Excess in the type-Ic SN 2020oi

“…In this paper, we assume a redshiftindependent distance of 17.1 Mpc corresponding to the distance derived from Cepheids (Freedman et al 1994a). We note that the distance adopted in the analysis for the Ca-rich transient SN 2019ehk in the same galaxy was 𝑑 ≈ 16.2 Mpc, while the distances used in the previous analyses of SN 2020oi were 14 Mpc,16.22 Mpc,and 16 Mpc,respectively Rho et al 2020;Tinyanont et al 2021). Although these values are roughly consistent, they will be the source of some discrepancy between the SN parameters derived in this work and those from the previous studies.…”

Modelling Type Ic Supernovae with TARDIS: Hidden Helium in SN1994I?

“…This highlights the critical importance of obtaining NIR spectra of SNe Ic in order to address the hidden helium question for a statistical sample of SNe. Future work will involve dedicated tardis modeling of the recent SN Ic 2020oi where NIR spectra are available (Rho et al 2020). The SN 2020oi modeling will use the recently developed tardis emulator (Kerzendorf et al 2020) which will enable us to produce posterior distributions for the He abundance.…”