GRB 161219B/SN 2016jca: A low-redshift gamma-ray burst supernova powered by radioactive heating

¹ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
e-mail: zewcano@gmail.com
² Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Københaven Ø, Denmark
³ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
⁴ Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavík, Iceland
⁵ DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, 2800 Lyngby, Denmark
⁶ Gran Telescopio Canarias (GRANTECAN), Cuesta de San José s/n, 38712 Breña Baja, La Palma, Spain
⁷ Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain
⁸ Departamento de Astronomía, Universidad de Chile, Camino del Observatorio 1515, Las Condes, Santiago, Chile
⁹ Millennium Institute of Astrophysics, Chile
¹⁰ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany
¹¹ INAF / Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate (LC), Italy
¹² INAF-Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone, Italy
¹³ ASI-Science Data Centre, Via del Politecnico snc, 00133 Rome, Italy
¹⁴ APC, Astroparticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
¹⁵ Centre for Astrophysics and Cosmology, University of Nova Gorica, Vipavska 11c, 5270 Ajdovščina, Slovenia
¹⁶ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands
¹⁷ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 76100 Rehovot, Israel
¹⁸ The Oskar Klein Centre, Department of Astronomy, AlbaNova, 106 91 Stockholm, Sweden
¹⁹ Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK

Received: 18 April 2017
Accepted: 5 July 2017

Abstract

Since the first discovery of a broad-lined type Ic supernova (SN) with a long-duration gamma-ray burst (GRB) in 1998, fewer than fifty GRB-supernovae (SNe) have been discovered. The intermediate-luminosity Swift GRB 161219B and its associated supernova SN 2016jca, which occurred at a redshift of z = 0.1475, represents only the seventh GRB-SN to have been discovered within 1 Gpc, and hence provides an excellent opportunity to investigate the observational and physical properties of these very elusive and rare type of SN. As such, we present optical to near-infrared photometry and optical spectroscopy of GRB 161219B and SN 2016jca, spanning the first three months since its discovery. GRB 161219B exploded in the disk of an edge-on spiral galaxy at a projected distance of 3.4 kpc from the galactic centre. GRB 161219B itself is an outlier in the E_p,i − E_γ,iso plane, while SN 2016jca had a rest-frame, peak absolute V-band magnitude of M_V = − 19.0 ± 0.1, which it reached after 12.3 ± 0.7 rest-frame days. We find that the bolometric properties of SN 2016jca are inconsistent with being powered solely by a magnetar central engine, and demonstrate that it was likely powered exclusively by energy deposited by the radioactive decay of nickel and cobalt into their daughter products, which were nucleosynthesised when its progenitor underwent core collapse. We find that 0.22 ± 0.08M_⊙ of nickel is required to reproducethe peak luminosity of SN 2016jca, and we constrain an ejecta mass of 5.8 ± 0.3M_⊙ and a kinetic energy of 5.1 ± 0.8 × 10⁵² erg. Finally, we report on a chromatic, pre-maximum bump in the g-band light curve, and discuss its possible origin.