Four GRB supernovae at redshifts between 0.4 and 0.8

The bursts GRB 071112C, 111228A, 120714B, and 130831A^⋆

¹ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
e-mail: klose@tls-tautenburg.de
² Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
³ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel
⁴ Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, 306, Santiago 22, Chile
⁵ Millennium Institute of Astrophysics (MAS), Nuncio Monseñor Sótero Sanz 100, Providencia, Santiago, Chile
⁶ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany
⁷ Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Santiago, Chile
⁸ American River College, Department of Physics and Astronomy, 4700 College Oak Drive, Sacramento CA, 95841, USA
⁹ Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 128 00 Prague 2, Czech Republic
¹⁰ Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
¹¹ INAF-OAS Bologna, Via Gobetti 93/3, 40129 Bologna, Italy
¹² Department of Chemistry and Physics, Roger Williams University, One Old Ferry Road, Bristol, RI 02809, USA

Received: 29 January 2018
Accepted: 19 November 2018

Abstract

Twenty years ago, GRB 980425/SN 1998bw revealed that long gamma-ray bursts (GRBs) are physically associated with broad-lined type-Ic supernovae (SNe). Since then more than 1000 long GRBs have been localized to high angular precision, but only in ∼50 cases has the underlying SN component been identified. Using the Gamma-Ray Burst Optical Near-Infrared Detector (GROND) multi-channel imager at ESO/La Silla, during the last ten years we have devoted a substantial amount of observing time to reveal and study SN components in long-GRB afterglows. Here we report on four more GRB SNe (associated with GRBs 071112C, 111228A, 120714B, and 130831A) which were discovered and/or followed-up with GROND and whose redshifts lie between z = 0.4 and 0.8. We study their afterglow light curves, follow the associated SN bumps over several weeks, and characterize their host galaxies. Using SN 1998bw as a template, the derived SN explosion parameters are fully consistent with the corresponding properties of the currently known GRB-SN ensemble, with no evidence for an evolution of their properties as a function of redshift. In two cases (GRB 120714B/SN 2012eb at z = 0.398 and GRB 130831A/SN 2013fu at z = 0.479) additional Very Large Telescope (VLT) spectroscopy of the associated SNe revealed a photospheric expansion velocity at maximum light of about 40 000 and 20 000 km s⁻¹, respectively. For GRB 120714B, which was an intermediate-luminosity burst, we find additional evidence for a black-body component in the light of the optical transient at early times, similar to what has been detected in some GRB SNe at lower redshifts.