A trio of gamma-ray burst supernovae:

GRB 120729A, GRB 130215A/SN 2013ez, and GRB 130831A/SN 2013fu^⋆

¹ Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik, Iceland
e-mail: zewcano@gmail.com
² Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008, Granada, Spain
³ Dark Cosmology Centre, Niels Bohr Institute, Juliane Maries Vej 30, Copenhagen Ø, 2100, Denmark
⁴ Space Research Institute, 117997, 84/32 Profsoyuznaya str., Moscow, Russia
⁵ School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
⁶ Department of Physics and Earth Sciences, University of Ferrara, via Saragat 1, 44122 Ferrara, Italy
⁷ European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001 Santiago 19, Chile
⁸ Unidad Asociada Grupo Ciencia Planetarias UPV/EHU-IAA/CSIC, Departamento de Física Aplicada I, E.T.S. Ingeniería, Universidad del País-Vasco UPV/EHU, Alameda de Urquijo s/n, 48013 Bilbao, Spain
⁹ Ikerbasque, Basque Foundation for Science, Alameda de Urquijo 36-5, 48008 Bilbao, Spain
¹⁰ The Oskar Klein Centre, AlbaNova, 106 91 Stockholm, Sweden
¹¹ INAF/Brera Astronomical Observatory, via Bianchi 46, 23807 Merate ( LC), Italy
¹² Astrophysics Research Institute, Liverpool John Moores University, Liverpool Science Park, 146 Brownlow Hill, Liverpool, L3 5RF, UK
¹³ Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
¹⁴ Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul Santiago, Chile
¹⁵ Millennium Center for Supernova Science, Casilla 36D Santiago, Chile
¹⁶ Faculty of Mathematics & Physics, University of Ljubljana, Jadranska ulica 19, 1000 Ljubljana, Slovenia
¹⁷ Department of Astronomy, University of California, Berkeley, CA 94720-3411, USA
¹⁸ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
¹⁹ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
²⁰ Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
²¹ Ulugh Beg Astronomical Institute, 100052, 33 Astronomicheskaya str., Tashkent, Uzbekistan
²² School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
²³ Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 70-264, 04510 Mexico, D.F., Mexico
²⁴ Department of Physics, Southern Methodist University, Dallas, Texas 75275, USA
²⁵ Isaac Newton Group of Telescopes, Apartado de Correos 321, 38700 Santa Cruz de La Palma, Canary Islands, Spain
²⁶ Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu HI 96822, USA
²⁷ NASA GoddardSpace Flight Center, MS 665, Greenbelt, MD 20771, USA
²⁸ Department of Astronomy and Space Sciences, Istanbul University Science Faculty, 34119 Istanbul, Turkey
²⁹ Astronomical Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
³⁰ School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
³¹ Institute of Solar-Terrestrial Physics, Siberian department of the Russian Academy of Sciences, p/o box 291, Lermontov str., 126a, 664033 Irkutsk, Russia
³² Institute of Astronomy of Kharkiv National University, 61022, 35 Sumska str., Kharkiv, Ukraine
³³ Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
³⁴ JSC Asronomical Scientific Center, Svobody str., 35, 22, 125362, Moscow, Russia
³⁵ Ussuriysk Astrophysical Observatory, 692533, Primorskiy kray, Ussuriyskiy rayon, s. Gornotayozhnoe, Russia
³⁶ Institute of Astrophysics, Academy of Sciences of Tajikistan, Bukhoro Str. 22, 734042 Dushanbe, Tajikistan
³⁷ Keldysh Institute of Applied Mathematics, 125047 Miusskaya sq., 4, Moscow, Russia
³⁸ Astronomy Department, University of California at Santa Cruz, CA 95064, USA
³⁹ Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 106, 22800 Ensenada, Baja California, Mexico
⁴⁰ Crimean Astrophysical Observatory, Taras Shevchenko National University of Kyiv, 98409, pgt. Nauchny, Crimea, Ukraine
⁴¹ Research School of Astronomy and Astrophysics, The Australian National University, ACT, 2611 Canberra, Australia

Received: 31 March 2014
Accepted: 14 May 2014

Abstract

We present optical and near-infrared (NIR) photometry for three gamma-ray burst supernovae (GRB-SNe): GRB 120729A, GRB 130215A/SN 2013ez, and GRB 130831A/SN 2013fu. For GRB 130215A/SN 2013ez, we also present optical spectroscopy at t − t₀ = 16.1 d, which covers rest-frame 3000–6250 Å. Based on Fe ii λ5169 and Si ii λ6355, our spectrum indicates an unusually low expansion velocity of ~4000–6350 km s^-1, the lowest ever measured for a GRB-SN. Additionally, we determined the brightness and shape of each accompanying SN relative to a template supernova (SN 1998bw), which were used to estimate the amount of nickel produced via nucleosynthesis during each explosion. We find that our derived nickel masses are typical of other GRB-SNe, and greater than those of SNe Ibc that are not associated with GRBs. For GRB 130831A/SN 2013fu, we used our well-sampled R-band light curve (LC) to estimate the amount of ejecta mass and the kinetic energy of the SN, finding that these too are similar to other GRB-SNe. For GRB 130215A, we took advantage of contemporaneous optical/NIR observations to construct an optical/NIR bolometric LC of the afterglow. We fit the bolometric LC with the millisecond magnetar model of Zhang & Mészáros (2001, ApJ, 552, L35), which considers dipole radiation as a source of energy injection to the forward shock powering the optical/NIR afterglow. Using this model we derive an initial spin period of P = 12 ms and a magnetic field of B = 1.1 × 10¹⁵ G, which are commensurate with those found for proposed magnetar central engines of other long-duration GRBs.