A search for Fermi bursts associated with supernovae and their frequency of occurrence

¹ Dip. di Fisica and ICRA, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy
e-mail: milosh.kovacevic@gmail.com; luca.izzo@gmail.com, wangyu@me.com
² Université de Nice Sophia Antipolis, Cedex 2, Grand Château Parc Valrose, Nice, France
³ ICRANet-Pescara, Piazza della Repubblica 10, 65122 Pescara, Italy
⁴ INAF–Napoli, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
⁵ INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica, Bologna, via Gobetti 101, 40129 Bologna, Italy
⁶ Department of Physics, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden
⁷ The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova, 106 91 Stockholm, Sweden
⁸ Department of Physics, Stockholm University, AlbaNova, 106 91 Stockholm, Sweden

Received: 29 July 2014
Accepted: 25 August 2014

Abstract

Context. Observations suggest that most long duration gamma-ray bursts (GRBs) are connected with broad-line supernovae Ib/c, (SNe-Ibc). The presence of GRB-SNe is revealed by rebrightenings emerging from the optical GRB afterglow 10–15 days, in the rest-frame of the source, after the prompt GRB emission.

Aims. Fermi/GBM has a field of view (FoV) about 6.5 times larger than the FoV of Swift, therefore we expect that a number of GRB-SN connections have been missed because of lack of optical and X-ray instruments on board of Fermi, which are essential for revealing SNe associated with GRBs. This has motivated our search in the Fermi catalog for possible GRB-SN events.

Methods. The search for possible GRB-SN associations follows two requirements: (1) SNe should fall inside the Fermi/GBM error box of the considered long GRB, and (2) this GRB should occur within 20 days before the SN event.

Results. We have found five cases within z< 0.2 fulfilling the above reported requirements. One of them, GRB 130702A-SN 2013dx, was already known to have a GRB-SN association. We have analyzed the remaining four cases and we have concluded that three of them are, very likely, just random coincidences due to the Fermi/GBM large error box associated with each GRB detection. We found one GRB possibly associated with a SN 1998bw-like source, GRB 120121B/SN 2012ba.

Conclusions. The very low redshift of GRB 120121B/SN 2012ba (z = 0.017) implies a low isotropic energy of this burst (E_iso = 1.39 × 10⁴⁸) erg. We then compute the rate of Fermi low-luminosity GRBs connected with SNe to be ρ_0,b ≤ 770 Gpc^-3 yr^-1. We estimate that Fermi/GBM could detect 1–4 GRBs-SNe within z ≤ 0.2 in the next 4 years.