GRB 161219B/SN 2016jca: a powerful stellar collapse. Issue 4 (10th June 2019)

• Record Type: Journal Article
• Authors: Ashall, C; Mazzali, P A; Pian, E; Woosley, S E; Palazzi, E; Prentice, S J; Kobayashi, S; Holmbo, S; Levan, A; Perley, D; Stritzinger, M D; Bufano, F; Filippenko, A V; Melandri, A; Oates, S; Rossi, A; Selsing, J; Zheng, W; Castro-Tirado, A J; Chincarini, G; D'Avanzo, P; De Pasquale, M; Emery, S; Fruchter, A S; Hurley, K; Moller, P; Nomoto, K; Tanaka, M; Valeev, A F
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 487:Issue 4(2019)
• Page Start: 5824
• Page End: 5839
• Publication Date: 2019-06-10
• Subjects: supernovae: general -- supernovae: individual; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz1588
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We report observations and analysis of the nearby gamma-ray burst GRB 161219B (redshift z = 0.1475) and the associated Type Ic supernova (SN) 2016jca. GRB 161219B had an isotropic gamma-ray energy of ∼1.6 × 10 50 erg. Its afterglow is likely refreshed at an epoch preceding the first photometric points (0.6 d), which slows down the decay rates. Combined analysis of the SN light curve and multiwavelength observations of the afterglow suggest that the GRB jet was broad during the afterglow phase (full opening angle ∼42° ± 3°). Our spectral series shows broad absorption lines typical of GRB supernovae (SNe), which testify to the presence of material with velocities up to ∼0.25c. The spectrum at 3.73 d allows for the very early identification of an SN associated with a GRB. Reproducing it requires a large photospheric velocity ($35\, 000 \pm 7000$ km s −1 ). The kinetic energy of the SN is estimated through models to be E kin ≈4 × 10 52 erg in spherical symmetry. The ejected mass in the explosion was M ej ≈6.5 ± 1.5 M⊙, much less than that of other GRB-SNe, demonstrating diversity among these events. The total amount of 56 Ni in the explosion was 0.27 ± 0.05 M⊙ . The observed spectra require the presence of freshly synthesized 56 Ni at the highest velocities, at least three times more than a standard GRB-SN. We also find evidence for a decreasing 56 Ni abundance as a function of decreasing velocity. This suggests that SN 2016jca was a highly aspherical explosion viewed close to on-axis, powered by a compact remnant. Applying a typical correction for asymmetry, the energy of SN 2016jca was ∼(1–3) × 10 52 erg, confirming that most of the energy produced by GRB-SNe goes into the kinetic energy of the SN ejecta.