What can we learn from GRBs?

Marco Muccino,Ana V Penacchioni,Soroush Shakeri,She-Sheng Xue,Rahim Moradi,Gregory V Vereshchagin,Jorge A Rueda,Yu Wang,Remo Ruffini,Yerlan Aimuratov,Milos Kovacevic,Giovanni B Pisani,Laura M Becerra,Mile Karlica,Julio D Melon Fuksman,Carlo L Bianco,Daria Primorac

doi:10.1051/epjconf/201816801015

Abstract

We review our recent results on the classification of long and short gamma-ray bursts (GRBs) in different subclasses. We provide observational evidences for the binary nature of GRB progenitors. For long bursts the induced gravitational collapse (IGC) paradigm proposes as progenitor a tight binary system composed of a carbon-oxygen core (COcore) and a neutron star (NS) companion; the supernova (SN) explosion of the COcore triggers a hypercritical accretion process onto the companion NS. For short bursts a NS–NS merger is traditionally adopted as the progenitor. We also indicate additional sub-classes originating from different progenitors: (COcore)–black hole (BH), BH–NS, and white dwarf–NS binaries. We also show how the outcomes of the further evolution of some of these sub-classes may become the progenitor systems of other sub-classes.

Highlights

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]
Short bursts are associated to neutron star (NS)-NS or black hole (BH)-NS mergers [12,13,14,15,16,17,18,19,20,21,22]: their host galaxies are of both early- and latetype, their localization with respect to the host galaxy often indicates a large offset [23,24,25,26,27,28,29] or a location of minimal star-forming activity with typical circumburst medium (CBM) densities of ∼ 10−5–10−4 cm−3, and no supernovae (SNe) have ever been associated to them
Recently we have found evindence for multiple components in long Gamma-ray bursts (GRBs) emissions evidencing the presence of a precise sequence of different astrophysical processes [33, 34], which led to the formulation of the Induced Gravitational Collapse (IGC) paradigm [6, 38,39,40] expliciting the role of binary systems as progenitors of the long GRBs

Summary

Introduction

Gamma-ray bursts (GRBs) are traditionally classified based on their duration [1,2,3,4,5]: short GRBs last 2 s, while long GRBs last 2 s. For progenitor system composed of a COcore in binary with an already formed BH [8, 42], leading to bursts with Eiso 1054 erg and Ep,i 2 MeV, the observational identification is still pending In these systems, which correspond to the late evolutionary stages of X-ray binaries as Cyg X-1 and Cyg X-3 [50], or microquasars [51], the hypercritical accretion produces, as out-states, a more massive BH and a νNS. Their occurrence rate can contribute to that of BdHNe, being COcore–BH a particular case of BdHN progenitors (see figure 1).

The fireshell model

XRFs and BdHNe in the IGC paradigm

The S-GRBs in the NS–NS merger paradigm

Conclusions