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

January 2024 • 2024ApJ...960L..18S

Authors • Srinivasaragavan, Gokul P. • Swain, Vishwajeet • O'Connor, Brendan • Anand, Shreya • Ahumada, Tomás • Perley, Daniel • Stein, Robert • Sollerman, Jesper • Fremling, Christoffer • Cenko, S. Bradley • Antier, S. • Guessoum, Nidhal • Hussenot-Desenonges, Thomas • Hello, Patrice • Lesage, Stephen • Hammerstein, Erica • Miller, M. Coleman • Andreoni, Igor • Bhalerao, Varun • Bloom, Joshua S. • Dutta, Anirban • Gal-Yam, Avishay • Hinds, K. -Ryan • Jaodand, Amruta • Kasliwal, Mansi • Kumar, Harsh • Kutyrev, Alexander S. • Ragosta, Fabio • Ravi, Vikram • Sharma, Kritti • Teja, Rishabh Singh • Yang, Sheng • Anupama, G. C. • Bellm, Eric C. • Coughlin, Michael W. • Mahabal, Ashish A. • Masci, Frank J. • Pathak, Utkarsh • Purdum, Josiah • Roberts, Oliver J. • Smith, Roger • Wold, Avery

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 ${E}_{\mathrm{KE}}={1.3}_{-1.2}^{+3.3}\times {10}^{51}\,\mathrm{erg}$ . 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.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2024ApJ...960L..18S
• PDF https://iopscience.iop.org/article/10.3847/2041-8213/ad16e7/pdf
• PREPRINT http://arxiv.org/abs/2310.14397
• ELECTR https://doi.org/10.3847%2F2041-8213%2Fad16e7