The story of SN 2021aatd -- a peculiar 1987A-like supernova with an early-phase luminosity excess

Abstract

There is a growing number of peculiar events that cannot be assigned to any of the main supernova (SN) classes. SN 1987A and a handful of similar objects, thought to be explosive outcomes of blue supergiant stars, belong to them: while their spectra closely resemble those of H-rich (IIP) SNe, their light-curve (LC) evolution is very different. Here we present the detailed photometric and spectroscopic analysis of SN 2021aatd, a peculiar Type II explosion: while its early-time evolution resembles that of the slowly evolving, double-peaked SN 2020faa (however, at a lower luminosity scale), after $\sim$40 days, its LC shape becomes similar to that of SN 1987A-like explosions. Beyond comparing LCs, color curves, and spectra of SN 2021aatd to that of SNe 2020faa, 1987A, and of other objects, we compare the observed spectra with our own SYN++ models and with the outputs of published radiative transfer models. We also modeled the pseudo-bolometric LCs of SNe 2021aatd and 1987A assuming a two-component (core+shell) ejecta, and involving the rotational energy of a newborn magnetar in addition to radioactive decay. We find that both the photometric and spectroscopic evolution of SN 2021aatd can be well described with the explosion of a $\sim$15 $M_{\odot }$ blue supergiant star. Nevertheless, SN 2021aatd shows higher temperatures and weaker Na ID and Ba II 6142 A lines than SN 1987A, which is reminiscent of rather to IIP-like atmospheres. With the applied two-component ejecta model (counting with both decay and magnetar energy), we can successfully describe the bolometric LC of SN 2021aatd, including the first $\sim$40-day long phase showing an excess compared to 87A-like SNe but being strikingly similar to that of the long-lived SN 2020faa. Nevertheless, finding a unified model that also explains the LCs of more luminous events (like SN 2020faa) is still a matter of concern.

arXiv comment24 pages, 18 figures, 10 tables; accepted for publication in A&A

References in corpus (39)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• ATLAS: A High-Cadence All-Sky Survey System
• Luminous Supernovae
• Characterizing the V-band light-curves of hydrogen-rich type II supernovae
• The diversity of Type II supernova versus the similarity in their progenitors
• Design and operation of the ATLAS Transient Science Server
• Radiation hydrodynamics of SN 1987A: I. Global analysis of the light curve for the first 4 months
• The Zwicky Transient Facility Bright Transient Survey. II. A Public Statistical Sample for Exploring Supernova Demographics
• SN 2005cs in M51 II. Complete Evolution in the Optical and the Near-Infrared
• The progenitor mass of the Type IIP supernova SN 2004et from late-time spectral modeling
• The first month of evolution of the slow rising type II-P SN 2013ej in M74
• The nebular spectra of SN 2012aw and constraints on stellar nucleosynthesis from oxygen emission lines
• FITSH -- a software package for image processing
• Quantitative Spectroscopy of Photospheric-Phase Type II Supernovae
• Caltech Core-Collapse Project (CCCP) Observations of Type II Supernovae: Evidence for Three Distinct Photometric Subtypes
• Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star
• Supernova 2012aw - a high-energy clone of archetypal type IIP SN 1999em
• The Type II-P Supernova 2017eaw: from explosion to the nebular phase
• Luminous Type II Short-Plateau Supernovae 2006Y, 2006ai, and 2016egz: A Transitional Class from Stripped Massive Red Supergiants
• A two-component model for fitting light-curves of core-collapse supernovae
• Measuring Expansion Velocities in Type II-P Supernovae
• First Results from Pan-STARRS1: Faint, High Proper Motion White Dwarfs in the Medium-Deep Fields
• Supernova 1987A: neutrino-driven explosions in three dimensions and light curves
• The Type II supernovae 2006V and 2006au: two SN 1987A-like events
• A semi-analytical light curve model and its application to type IIP supernovae
• Long-rising Type II supernovae from PTF and CCCP
• Models for the Unusual Supernova iPTF14hls
• Supernova 1987A: 3D Mixing and light curves for explosion models based on binary-merger progenitors
• Explosions of blue supergiants from binary mergers for SN 1987A
• Late-time observations of the extraordinary Type II supernova iPTF14hls
• The Continuing Story of SN IIb 2013df: New Optical and IR Observations and Analysis
• Supernova SN 2020faa -- an iPTF14hls look-alike?
• Influence of macroclumping on type II supernova light curves
• Optical Rebrightening of Extragalactic Transients from the Zwicky Transient Facility
• SN 2018hna: Adding a Piece to the Puzzles of the Explosion of Blue Supergiants
• Optical photometry and spectroscopy of the 1987A-like supernova 2009mw
• Three is the magic number -- distance measurement of NGC 3147 using SN 2021hpr and its siblings
• Long-rising Type II Supernovae in the Zwicky Transient Facility Census of the Local Universe
• Hidden shock powering the peak of SN 2020faa

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