Harvey, Luke and Maguire, Kate and Magee, Mark R. and Bulla, Mattia and Dhawan, Suhail and Schulze, Steve and Sollerman, Jesper and Deckers, Maxime and Dimitriadis, Georgios and Reusch, Simeon and Smith, Mathew and Terwel, Jacco and Coughlin, Michael W. and Masci, Frank and Purdum, Josiah and Reedy, Alexander and Robert, Estelle and Wold, Avery (2023) Early-time spectroscopic modelling of the transitional Type Ia Supernova 2021rhu with TARDIS. Monthly Notices of the Royal Astronomical Society, 522 (3). pp. 4444-4467. ISSN 0035-8711
Full text not available from this repository.Abstract
An open question in SN Ia research is where the boundary lies between 'normal' Type Ia supernovae (SNe Ia) that are used in cosmological measurements and those that sit off the Phillips relation. We present the spectroscopic modelling of one such '86G-like' transitional SN Ia, SN 2021rhu, that has recently been employed as a local Hubble Constant calibrator using a tip of the red-giant branch measurement. We detail its modelling from -12 d until maximum brightness using the radiative-transfer spectral-synthesis code tardis. We base our modelling on literature delayed-detonation and deflagration models of Chandrasekhar mass white dwarfs, as well as the double-detonation models of sub-Chandrasekhar mass white dwarfs. We present a new method for 'projecting' abundance profiles to different density profiles for ease of computation. Due to the small velocity extent and low outer densities of the W7 profile, we find it inadequate to reproduce the evolution of SN 2021rhu as it fails to match the high-velocity calcium components. The host extinction of SN 2021rhu is uncertain but we use modelling with and without an extinction correction to set lower and upper limits on the abundances of individual species. Comparing these limits to literature models we conclude that the spectral evolution of SN 2021rhu is also incompatible with double-detonation scenarios, lying more in line with those resulting from the delayed detonation mechanism (although there are some discrepancies, in particular a larger titanium abundance in SN 2021rhu compared to the literature). This suggests that SN 2021rhu is likely a lower luminosity, and hence lower temperature, version of a normal SN Ia.