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  • Srinivasaragavan, Gokul P; Swain, Vishwajeet; O'Connor, Brendan M; Anand, Shreya; Ahumada, Tomás; Perley, Daniel A; Stein, Robert; Sollerman, Jesper; Fremling, Christoffer; S Bradley Cenko; Antier, Sarah; Guessoum, Nidhal; Thomas Hussenot-Desenonges; Hello, Patrice; Lesage, Stephen; Hammerstein, Erica; M Coleman Miller; Andreoni, Igor; Bhalerao, Varun; Bloom, Joshua S; Dutta, Anirban; Gal-Yam, Avishay; K-Ryan Hinds; Jaodand, Amruta D; Kasliwal, Mansi M; Kumar, Harsh; Kutyrev, Alexander; Ragosta, Fabio; Ravi, Vikram; Sharma, Kritti; Teja, Rishabh S; 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

    arXiv.org, 12/2023
    Paper, Journal Article

    We report observations of the optical counterpart of the long gamma-ray burst (LGRB) GRB 230812B, and its associated supernova (SN) SN 2023pel. The proximity (\(z = 0.36\)) and high energy (\(E_{\gamma, \rm{iso}} \sim 10^{53}\) 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 \(M_r = -19.46 \pm 0.18\) 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 \(M_{\rm{Ni}} = 0.38 \pm 0.01\) \(\rm{M_\odot}\), and a peak bolometric luminosity of \(L_{\rm{bol}} \sim 1.3 \times 10^{43}\) \(\rm{erg}\) \(\rm{s^{-1}}\). We confirm SN 2023pel's classification as a broad-lined Type Ic SN with a spectrum taken 15.5 days after its peak in \(r\) band, and derive a photospheric expansion velocity of \(v_{\rm{ph}} = 11,300 \pm 1,600\) \(\rm{km}\) \(\rm{s^{-1}}\) at that phase. Extrapolating this velocity to the time of maximum light, we derive the ejecta mass \(M_{\rm{ej}} = 1.0 \pm 0.6\) \(\rm{M_\odot}\) and kinetic energy \(E_{\rm{KE}} = 1.3^{+3.3}_{-1.2} \times10^{51}\) \(\rm{erg}\). 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 \(E_{\gamma, \rm{iso}}\) 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.