Optical polarization and spectral properties of the hydrogen-poor superluminous supernovae SN 2021bnw and SN 2021fpl. Issue 4 (20th March 2023)

• Record Type: Journal Article
• Authors: Poidevin, F; Omand, C M B; Könyves-Tóth, Réka; Pérez-Fournon, I; Clavero, R; Geier, S; Jimenez Angel, C; Marques-Chaves, R; Shirley, R
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 521:Issue 4(2023)
• Page Start: 5418
• Page End: 5439
• Publication Date: 2023-03-20
• Subjects: techniques: photometric -- techniques: polarimetric -- techniques: spectroscopic -- (stars:) supernovae: general -- (stars:) supernovae: individual: LSQ14mo, SN 2015bn, SN 2017egm, SN 2018bsz, SN 2020ank, SN 2020znr, SN 2021bnw, SN 2021fpl; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stad830
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: New optical photometric, spectroscopic, and imaging polarimetry data are combined with publicly available data to study some of the physical properties of the two hydrogen-poor superluminous supernovae (SLSNe) SN 2021bnw and SN 2021fpl. For each SLSN, the best-fitting parameters obtained from the magnetar model with Modular Open-Source Fitter for Transients do not depart from the range of parameter obtained on other SLSNe discussed in the literature. A spectral analysis with SYN++ shows that SN 2021bnw is a W type, fast evolver, while SN 2021fpl is a 15bn type, slow evolver. The analysis of the polarimetry data obtained on SN 2021fpl at four epochs (+1.8, +20.6, +34.1, and +43.0 d, rest frame) shows >3σ polarization detections in the range of 0.8–1 per cent. A comparison of the spectroscopy data suggests that SN 2021fpl underwent a spectral transition a bit earlier than SN 2015bn, during which, similarly, it could have underwent a polarization transition. The analysis of the polarimetry data obtained on SN 2021bnw does not show any departure from symmetry of the photosphere at an empirical diffusion time-scale of ≈2 (+81.1 d rest frame). This result is consistent with those on the sample of W-type SLSN observed at empirical diffusion time-scale ≤ 1 with that technique, even though it is not clear the effect of limited spectral windows varying from one object to the other. Measurements at higher empirical diffusion time-scale may be needed to see any departure from symmetry as it is discussed in the literature for SN 2017egm.