On the Induced Gravitational Collapse Scenario of Gamma-Ray Bursts Associated With Supernovae

Abstract

Following the induced gravitational collapse (IGC) paradigm of gamma-ray bursts (GRBs) associated with type Ib/c supernovae, we present numerical simulations of the explosion of a carbon-oxygen (CO) core in a binary system with a neutron-star (NS) companion. The supernova ejecta trigger a hypercritical accretion process onto the NS thanks to a copious neutrino emission and the trapping of photons within the accretion flow. We show that temperatures 1-10 MeV develop near the NS surface, hence electron-positron annihilation into neutrinos becomes the main cooling channel leading to accretion rates 10 −9 -10 −1 M s −1 and neutrino luminosities 10 43 -10 52 erg s −1 (the shorter the orbital period the higher the accretion rate). We estimate the maximum orbital period, P max , as a function of the NS initial mass, up to which the NS companion can reach by hypercritical accretion the critical mass for gravitational collapse leading to black-hole (BH) formation. We then estimate the effects of the accreting and orbiting NS companion onto a novel geometry of the supernova ejecta density profile. We present the results of a 1.4 × 10 7 particle simulation which show that the NS induces accentuated asymmetries in the ejecta density around the orbital plane. We elaborate on the observables associated with the above features of the IGC process. We apply this framework to specific GRBs: we find that X-ray flashes (XRFs) and binary-driven hypernovae (BdHNe) are produced in binaries with P > P max and P < P max , respectively. We analyze in detail the case of XRF 060218.

What can we learn from GRBs?

“…Specific constant power-law behaviors are observed in their high energy GeV and Xrays luminosity light curves [9,46,47]. The out-states of BdHNe are νNS-BH binaries [41,42,48,49]. The BdHN occurrence rate is ρ BdHN = 0.77 +0.09 −0.08 Gpc −3 yr −1 [42] (see figure 1).…”

The binary progenitors of short and long GRBs and their gravitational-wave emission

“…Long bursts with E iso 10 52 erg are instead produced by more compact CO core -NS binaries (a 10 11 cm, see e.g., Refs. [13,15]). In this case the SN triggers a larger accretion rate onto the NS companion, e.g.…”

“…In the case of long GRBs we stand on the induced gravitational collapse (IGC) scenario that introduces as their progenitors short-period binaries composed of a carbon-oxygen core (CO core ) with a NS companion [9][10][11][12][13][14][15]. The core-collapse of the CO core , which forms a NS as central remnant (hereafter νNS), leads also to a SN explosion that triggers a massive, hypercritical accretion process onto the NS companion.…”

“…2 shows a simulation of an IGC process presented in Ref. [15]. We considered the effects of the gravitational field of the NS on the SN ejecta including the orbital motion as well as the changes in the NS gravitational mass owing to the accretion process via the Bondi formalism.…”

Neutrino Oscillations within the Induced Gravitational Collapse Paradigm of Long Gamma-Ray Bursts

“…The role of neutrinos in this paradigm has been recently addressed Fryer et al (2014); Fryer et al (2015); Becerra et al (2015Becerra et al ( , 2016. The hypercritical accretion of the SN ejecta onto the NS companion can reach very high rates of up to 10 −2 M s −1 and its duration can be of the order of 10-10 4 s depending on the binary parameters.…”