Induced Gravitational Collapse, Binary-Driven Hypernovae, Long Gramma-ray Bursts and Their Connection with Short Gamma-ray Bursts

Abstract

There is increasing observational evidence that short and long Gamma-ray bursts (GRBs) originate in different subclasses, each one with specific energy release, spectra, duration, etc, and all of them with binary progenitors. The binary components involve carbon-oxygen cores (CO core ), neutron stars (NSs), black holes (BHs), and white dwarfs (WDs). We review here the salient features of the specific class of binary-driven hypernovae (BdHNe) within the induced gravitational collapse (IGC) scenario for the explanation of the long GRBs. The progenitor is a CO core -NS binary. The supernova (SN) explosion of the CO core , producing at its center a new NS (νNS), triggers onto the NS companion a hypercritical, i.e., highly super-Eddington accretion process, accompanied by a copious emission of neutrinos. By accretion the NS can become either a more massive NS or reach the critical mass for gravitational collapse with consequent formation of a BH. We summarize the results on this topic from the first analytic estimates in 2012 all the way up to the most recent three-dimensional (3D) smoothed-particle-hydrodynamics (SPH) numerical simulations in 2018. Thanks to these results it is by now clear that long GRBs are richer and more complex systems than thought before. The SN explosion and its hypercritical accretion onto the NS explain the X-ray precursor. The feedback of the NS accretion, the NS collapse and the BH formation produce asymmetries in the SN ejecta, implying the necessity of a 3D analysis for GRBs. The newborn BH, the surrounding matter and the magnetic field inherited from the NS, comprises the inner engine from which the GRB electron-positron (e + e − ) plasma and the high-energy emission are initiated. The impact of the e + e − on the asymmetric ejecta transforms the SN into a hypernova (HN). The dynamics of the plasma in the asymmetric ejecta leads to signatures depending on the viewing angle. This explains the ultrarelativistic prompt emission in the MeV domain and the mildly-relativistic flares in the early afterglow in the X-ray domain. The feedback of the νNS pulsar-like emission on the HN explains the X-ray late afterglow and its power-law regime. All of the above is in contrast with a simple GRB model attempting to explain the entire GRB with the kinetic energy of an ultrarelativistic jet extending through all of the above GRB phases, as traditionally proposed in the "collapsar-fireball" model. In addition, BdHNe in their different flavors lead to νNS-NS or νNS-BH binaries. The gravitational wave emission drives these binaries to merge producing short GRBs. It is thus established a previously unthought interconnection between long and short GRBs and their occurrence rates. This needs to be accounted for in the cosmological evolution of binaries within population synthesis models for the formation of compact-object binaries.

Neutrino Oscillations in Neutrino-Dominated Accretion Around Rotating Black Holes

“…Since the disk is assumed to be in a steady-state, we then perform a time average of Equation (62) as discussed in Section 2. With the new distributions, we can calculate the new neutrino and antineutrino average energies and use them to re-integrate the disk equations.…”

“…This is summarized in Table 1, taken from [61]. For a review on the BdHN model and all the physical phenomena at work, we refer the reader to [62].…”

“…Adapted from Table 1 in [61] with the permission of the authors. References in the table: a [60], b [57,62,63], c [64], d [65,66], e [67], f [60,68]. The emission of neutrinos is a crucial ingredient, since they act as the main cooling process that allows the accretion onto the NS to proceed at very high rates of up to 1 M s −1 [57,59,63,69,70].…”

Some recent results on neutrino osillations in hypercritical accretion

“…The NS then reaches its critical mass for gravitational collapse, hence forming a rotating black hole (BH) (Becerra et al ; Becerra et al ). These systems have been called binary‐driven hypernovae (BdHNe), and they lead to a variety of observable emissions from the X‐rays all the way to high‐energy gamma rays (see e.g.,[Rueda et al ; Ruffini et al ] for details).…”

Editorial for the Special Issue “Accretion Disks, Jets, Gamma-Ray Bursts and Related Gravitational Waves”

“…Subsequently, this collapsar disk produces jets manifested as a gamma-ray burst. However, Jorge Rueda, Remo Ruffini and Y. Wang looked at the problem from a different angle and argued for the connection of long duration gamma-ray bursts with their short duration counterparts [18]. They elaborate their idea and related physics in detail in this Issue.…”