GRB 140619b: A Short GRB From a Binary Neutron Star Merger Leading to Black Hole Formation

What can we learn from GRBs?

“…This result is also in good agreement with the NS-NS binaries observed within our Galaxy: only a subset of them has a total mass larger than the NS critical mass M NS crit and can form a BH in their merging process [10] if we assume that M NS crit = 2.67M � for a non-rotating, globally neutral NS within the NL3 nuclear model [87]. In this light S-GRBs are very important for inferring constraints on M NS crit , on the NS equation of state, and on the minimum mass of the newly-formed BH.…”

“…The spectrum of the P-GRB is determined by the geometry of the pair-creation region: in the case of the spherically symmetric dyadosphere, the P-GRB spectrum is generally described by a single thermal component [42]. [10,63]; in the case of an axially symmetric dyadotorus, the resulting P-GRB spectrum is a convolution of thermal spectra of different temperatures which resembles more a power-law spectral energy distribution with an exponential cutoff [64,65].…”

“…The structures observed in the prompt emission of a GRB depend on the CBM density n CBM and its inhomogeneities [66][67][68]. In both long and short bursts the CBM clouds have similar masses (10 22 -10 24 g), sizes (≈ 10 15 -10 16 cm), and typical distances from the BH (≈ 10 16 -10 17 cm) [10,33]. The observed prompt emission spectrum results from the convolution of a large number of comoving spectra with decreasing temperatures and Lorentz and Doppler factors, due to each collision with the CBM, over the surfaces of constant arrival time for photons at the detector [69,70] over the entire observation time.…”

“…Thanks to the extensive data collected by γ-ray telescopes, such as AGILE, BATSE, BeppoSAX, Fermi, HETE-II, INTEGRAL, Konus/WIND and Swift, to more sofisticated time-resolved spectral analyses, and to the theoretical treatment of the fireshell model [6][7][8] it has become evident that both long and short bursts originate from binary progenitors and that they can be further subdivided into a variety of sub-classes, depending on the evolution of these binary systems [9][10][11].…”

“…For NS-NS binaries, which are the outcomes of XRFs, we have [10,42,48]: -Short gamma-ray flashes (S-GRFs), with E iso 10 52 erg and E p,i 2 MeV. They occur when the merged core does not exceed the NS critical mass and does not collapse into a BH, but still remains as a MNS with some additional orbiting material to guarantee the angular momentum conservation.…”