Close, bright, and boxy: the superluminous SN 2018hti

• DOI: 10.1093/mnras/stac744
• Publication Date: 2022-03-15T20:15:25Z
• Authors: A Fiore; S Benetti; M Nicholl; A Reguitti; E Cappellaro; S Campana; S Bose; E Paraskeva; E Berger; T M Bravo; J Burke; Y-Z Cai; T-W Chen; P Chen; R Ciolfi; S Dong; S Gomez; M Gromadzki; C P Gutiérrez; D Hiramatsu; G Hosseinzadeh; D A Howell; A Jerkstrand; E Kankare; A Kozyreva; K Maguire; C McCully; P Ochner; C Pellegrino; G Pignata; R S Post; N Elias-Rosa; M Shahbandeh; S Schuldt; B P Thomas; L Tomasella; J Vinkó; C Vogl; J C Wheeler; D R Young
• Keywords: High Energy Astrophysical Phenomena (astro-ph.HE); ta115; Supernovae: general; 500; FOS: Physical sciences; Astronomy and Astrophysics; Supernovae: individual: SN 2018hti; Astrophysics / csillagászat; 7. Clean energy; 520; asztrofizika; Astrophysics - Solar and Stellar Astrophysics; Space and Planetary Science; 13. Climate action; QC Physics / fizika; QB Astronomy; Astrophysics - High Energy Astrophysical Phenomena; Solar and Stellar Astrophysics (astro-ph.SR)

ABSTRACT SN 2018hti was a very nearby (z = 0.0614) superluminous supernova with an exceedingly bright absolute magnitude of −21.7 mag in r band at maximum. The densely sampled pre-maximum light curves of SN 2018hti show a slow luminosity evolution and constrain the rise time to ∼50 rest-frame d. We fitted synthetic light curves to the photometry to infer the physical parameters of the explosion of SN 2018hti for both the magnetar and the CSM-interaction scenarios. We conclude that one of two mechanisms could be powering the luminosity of SN 2018hti; interaction with ∼10 M⊙ of circumstellar material or a magnetar with a magnetic field of Bp∼ 1.3 × 1013 G, and initial period of Pspin∼ 1.8 ms. From the nebular spectrum modelling we infer that SN 2018hti likely results from the explosion of a ${\sim}40\, \mathrm{M}_\odot$ progenitor star.