GRB 140619B: A short GRB from a binary neutron star merger leading to black hole formation

Abstract

For short gamma-ray bursts (GRBs), double neutron star (NS) mergers are traditionally adopted as progenitors. We propose a classification of short bursts into two sub-classes: short gamma-ray flashes (S-GRFs) with isotropic energy E iso 10 52 erg and rest-frame spectral peak energy E p,i 2 MeV, when the merger leads to a very massive NS (MNS), and the authentic short GRBs (S-GRBs) with E iso 10 52 erg and E p,i 2 MeV, when a black hole (BH) is formed. Evidences for the BH formation in S-GRBs are provided by the observed high energy 0.1-100 GeV emission after the GRB emission from the e + e − -plasma transparency (P-GRB); in S-GRFs, leading to MNS, this emission is never observed. Both these sub-classes fulfill the E p,i -E iso relation for short GRBs. We present here the recently identified S-GRB 140619B. From the spectral analysis of the early ∼ 0.2 s, we infer an observed P-GRB temperature kT = (324 ± 33) keV, a theoretically derived redshift z = 2.67 ± 0.37, a total burst energy E tot e + e − = (6.03 ± 0.79) × 10 52 erg, and a baryon load B = (5.52 ± 0.73) × 10 −5 . We also estimate the emission of gravitational waves (GWs) of the progenitor NS-NS merger. Including all the S-GRBs so far identified, the observed rate of these sources is ρ 0 = 3.5 +3.4 −2.0 × 10 −4 Gpc −3 yr −1 .

GRB 140619B: a short GRB from a neutron star merger leading to the black hole formation

“…More details on the spectral analysis can be found in Ref. [11]. We interpret the above data within the fireshell model of GRBs [12,13,14].…”

“…Following the analysis described in Refs. [4,11], from the above ratio, by applying the fireshell equations of motion, we obtained the redshift z = 2.67 ± 0.37, the baryon load B = (5.52 ± 0.73) × 10 −5 , and the total e + e − plasma energy E tot e + e − = (6.03 ± 0.79) × 10 52 ergs. The BGO-b1 (0.26-40 MeV) prompt emission light curve in Fig.…”