Characterizing the Ordinary Broad-line Type Ic SN 2023pel from the Energetic GRB 230812B

Srinivasaragavan, GP ORCID: 0000-0002-6428-2700, Swain, V ORCID: 0000-0002-7942-8477, O’Connor, B ORCID: 0000-0002-9700-0036, Anand, S ORCID: 0000-0003-3768-7515, Ahumada, T ORCID: 0000-0002-2184-6430, Perley, D ORCID: 0000-0001-8472-1996, Stein, R ORCID: 0000-0003-2434-0387, Sollerman, J ORCID: 0000-0003-1546-6615, Fremling, C ORCID: 0000-0002-4223-103X, Cenko, SB ORCID: 0000-0003-1673-970X, Antier, S ORCID: 0000-0002-7686-3334, Guessoum, N ORCID: 0000-0003-1585-8205, Hussenot-Desenonges, T ORCID: 0009-0009-2434-432X, Hello, P, Lesage, S ORCID: 0000-0001-8058-9684, Hammerstein, E ORCID: 0000-0002-5698-8703, Miller, MC ORCID: 0000-0002-2666-728X, Andreoni, I ORCID: 0000-0002-8977-1498, Bhalerao, V ORCID: 0000-0002-6112-7609, Bloom, JS ORCID: 0000-0002-7777-216X et al (2024) Characterizing the Ordinary Broad-line Type Ic SN 2023pel from the Energetic GRB 230812B. Astrophysical Journal Letters, 960 (2). L18-L18. ISSN 2041-8205

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Abstract

We report observations of the optical counterpart of the long gamma-ray burst (GRB) GRB 230812B and its associated supernova (SN) SN 2023pel. The proximity (z = 0.36) and high energy (E γ,iso ∼ 1053 erg) make it an important event to study as a probe of the connection between massive star core collapse and relativistic jet formation. With a phenomenological power-law model for the optical afterglow, we find a late-time flattening consistent with the presence of an associated SN. SN 2023pel has an absolute peak r-band magnitude of M r = −19.46 ± 0.18 mag (about as bright as SN 1998bw) and evolves on quicker timescales. Using a radioactive heating model, we derive a nickel mass powering the SN of M Ni = 0.38 ± 0.01 M ⊙ and a peak bolometric luminosity of L bol ∼ 1.3 × 1043 erg s−1. We confirm SN 2023pel’s classification as a broad-line Type Ic SN with a spectrum taken 15.5 days after its peak in the r band and derive a photospheric expansion velocity of v ph = 11,300 ± 1600 km s−1 at that phase. Extrapolating this velocity to the time of maximum light, we derive the ejecta mass M ej = 1.0 ± 0.6 M ⊙ and kinetic energy E KE = 1.3 − 1.2 + 3.3 × 10 51 erg . We find that GRB 230812B/SN 2023pel has SN properties that are mostly consistent with the overall GRB-SN population. The lack of correlations found in the GRB-SN population between SN brightness and E γ,iso for their associated GRBs across a broad range of 7 orders of magnitude provides further evidence that the central engine powering the relativistic ejecta is not coupled to the SN powering mechanism in GRB-SN systems.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
Date of acceptance:	9 December 2023
Date of first compliant Open Access:	16 February 2024
Date Deposited:	16 Feb 2024 15:22
Last Modified:	04 Jul 2025 14:00
DOI or ID number:	10.3847/2041-8213/ad16e7
URI:	https://researchonline.ljmu.ac.uk/id/eprint/22641

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