Abstract:
We present the analysis of the luminous Type II Supernova (SN) 2021tsz, which exploded in a low-luminosity galaxy. It reached a peak magnitude of −18.88 ± 0.13 mag in the r band and exhibited an initial rapid decline of 4.05 ± 0.14 mag (100 d)−1 from peak luminosity till ∼30 d. The photospheric phase is short, with the SN displaying bluer colours and a weak Hα absorption component–features consistent with other luminous, short-photospheric phase Type II SNe. A distinct transition from the photospheric to the radioactive tail phase in the V band–as is common in hydrogen-rich Type II SNe–is not visible in SN 2021tsz, although a modest ∼1 mag drop is apparent in the redder filters. Hydrodynamic modelling suggests the luminosity is powered by ejecta-circumstellar material (CSM) interaction during the early phases (<30 days). Interaction with 0.6 M of dense CSM extending to 3100 R reproduces the observed luminosity, with an explosion energy of 1.3 × 1051 erg. The modelling indicates a pre-SN mass of 9 M , which includes a hydrogen envelope of 4 M , and a radius of ∼1000 R . Spectral energy distribution analysis and strong-line diagnostics revealed that the host galaxy of SN 2021tsz is a low-metallicity, dwarf galaxy. The low-metallicity environment and the derived high mass loss from the hydrodynamical modelling strongly support a binary progenitor system for SN 2021tsz.
Description:
Open Access
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
