SN 2020ank: a bright and fast-evolving H-deficient superluminous supernova. Issue 2 (18th January 2021)

• Record Type: Journal Article
• Authors: Kumar, Amit; Kumar, Brajesh; Pandey, S B; Sahu, D K; Singh, Avinash; Anupama, G C; Aryan, Amar; Gupta, Rahul; Dutta, Anirban; Misra, Kuntal
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 502:Issue 2(2021)
• Page Start: 1678
• Page End: 1693
• Publication Date: 2021-01-18
• Subjects: techniques: photometric -- techniques: spectroscopic -- supernovae: general -- supernovae: individual: SN 2020ank; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa4047
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We investigate the observational properties of a hydrogen-deficient superluminous supernova (SLSN) SN 2020ank (at z = 0.2485), with the help of early phase observations carried out between –21 and +52 d since g -band maximum. Photometrically, SN 2020ank is one of the brightest SLSN ($M_{\mathrm{ g, peak}}\, \sim$ –21.84 ± 0.10 mag), having fast pre-peak rising and post-peak decaying rates. The bolometric light curve of SN 2020ank exhibits a higher peak luminosity ( L max ) of ∼ (3.9 ± 0.7) × 10 44 erg s −1 and appears to be symmetric around the peak with $L^{\mathrm{ rise}}_{\mathrm{ max}}$ /e ${\approx}L^{\mathrm{ fall}}_{\mathrm{ max}}$ /e ≈ 15 d. The semi-analytical light-curve modelling using the minim code suggests a spin-down millisecond magnetar with $P_i\, \sim$ 2.2 ± 0.5 ms and $B\, \sim$ (2.9 ± 0.1) $\times \, 10^{14}$ G as a possible powering source for SN 2020ank. The possible magnetar origin and excess ultraviolet flux at early epochs indicate a central-engine based powering source for SN 2020ank. Near-peak spectra of SN 2020ank are enriched with the W-shaped O ii features but with the weaker signatures of C ii and Fe iii . Using the estimated rise time of ∼ 27.9 d and the photospheric velocity of ∼ 12 050 km s −1, we constrain the ejecta mass to ∼ 7.2 M⊙ and the kinetic energy of ∼6.3 × 10 51 erg. The near-peak spectrum of SN 2020ank exhibits a close spectral resemblance with that of fast-evolving SN 2010gx. The absorption features of SN 2020ank are blueshifted compared to Gaia16apd, suggesting a higher expansion velocity. The spectral similarity with SN 2010gx and comparatively faster spectral evolution than PTF12dam (a slow-evolving SLSN) indicate the fast-evolving behaviour of SN 2020ank.