Close, bright and boxy: the superluminous SN 2018hti

• Main Authors: Fiore, A, Benetti, S, Nicholl, M, Reguitti, A, Cappellaro, E, Campana, S, Bose, S, Paraskeva, E, Berger, E, Bravo, T. M, Burke, J, Cai, Y. -Z, Chen, T. -W, Chen, P, Ciolfi, R, Dong, S, Gomez, S, Gromadzki, M, Gutiérrez, C. P, Hiramatsu, D, Hosseinzadeh, G, Howell, D. A, Jerkstrand, A, Kankare, E, Kozyreva, A, Maguire, K, McCully, C, Ochner, P, Pellegrino, C, Pignata, G, Post, R. S, Elias-Rosa, N, Shahbandeh, M, Schuldt, S, Thomas, B. P, Tomasella, L, Vinkó, J, Vogl, C, Wheeler, J. C, Young, D. R
• Format: Journal Article
• Language: English
• Published: 13.11.2021
• Subjects: Physics - High Energy Astrophysical Phenomena; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.2111.07142

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 days. 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 Msun of circumstellar material or a magnetar with a magnetic field of B_p~1.3e13 G and initial period of P_spin~1.8 ms. From the nebular spectrum modelling we infer that SN 2018hti likely results from the explosion of a ~40 Msun progenitor star.