The Blackholic energy and the canonical Gamma-Ray Burst IV: the “long,” “genuine short” and “fake—disguised short” GRBs

Abstract

We report some recent developments in the understanding of GRBs based on the theoretical framework of the "fireshell" model, already presented in the last three editions of the "Brazilian School of Cosmology and Gravitation". After recalling the basic features of the "fireshell model", we emphasize the following novel results: 1) the interpretation of the X-ray flares in GRB afterglows as due to the interaction of the optically thin fireshell with isolated clouds in the CircumBurst Medium (CBM); 2) an interpretation as "fake -disguised" short GRBs of the GRBs belonging to the class identified by Norris & Bonnell; we present two prototypes, GRB 970228 and GRB 060614; both these cases are consistent with an origin from the final coalescence of a binary system in the halo of their host galaxies with particularly low CBM density n cbm ∼ 10 −3 particles/cm 3 ; 3) the first attempt to study a genuine short GRB with the analysis of GRB 050509B, that reveals indeed still an open question; 4) the interpretation of the GRB-SN association in the case of GRB 060218 via the "induced gravitational collapse" process; 5) a first attempt to understand the nature of the "Amati relation", a phenomenological correlation between the isotropic-equivalent radiated energy of the prompt emission E iso with the cosmological rest-frame νF ν spectrum peak energy E p,i . In addition, recent progress on the thermalization of the electron-positron plasma close to their formation phase, as well as the structure of the electrodynamics of Kerr-Newman Black Holes are presented. An outlook for possible explanation of high-energy phenomena in GRBs to be expected from the AGILE and the Fermi satellites are discussed. As an example of high energy process, the work by Enrico Fermi dealing with ultrarelativistic collisions is examined. It is clear that all the GRB physics points to the existence of overcritical electrodynamical fields. In this sense we present some progresses on a unified approach to heavy nuclei and neutron stars cores, which leads to the existence of overcritical fields under the neutron star crust.1 Part I, Part II and Part III of these Lecture notes have been published respectively in COSMOLOGY AND GRAVITATION: ]. The outcome of this analysis points to the existence of a "canonical" GRB, originating from a variety of different initial astrophysical scenarios. The communality of these GRBs appears to be that they all are emitted in the process of formation of a black hole with a negligible value of its angular momentum. The following sequence of events appears to be canonical: the gravitational collapse to a black hole, the vacuum polarization process in the dyadosphere with the creation of the optically thick self accelerating electron-positron plasma; the engulfment of baryonic mass during the plasma expansion; adiabatic expansion of the optically thick "fireshell" of electron-positronbaryon plasma up to the transparency; the interaction of the accelerated baryonic matter with the CircumBurst Medium (CBM). This leads to the canoni...

Fundamental Physics From Black Holes, Neutron Stars and Gamma-Ray Bursts

“…The mission was inspired by an unconventional proposal by our colleague Yacob Borisovich Zel'dovich. [40][41][42] The first public announcement of the GRB discovery occurred in a session I organized with Herb Gursky at the AAAS meeting in San Francisco. 43 On the meager observational evidence of the results presented in San Francisco, I worked out a model for GRBs with Thibault Damour, based on the possibility of explaining the origin of their gamma and X-ray fluxes by the process of vacuum polarization "a la Heisenberg-Euler-Schwinger" occurring around a black hole endowed with electromagnetic structure.…”

Spreading of ultrarelativistically expanding shell: An application to GRBs

“…Early treatments assuming the absence of baryons and thin shell approximation (Bianco et al, 2001), and non instantaneous energy release (Ruffini et al, 2005) produced estimations of P-GRBs duration ∼ 10 −2 − 10 −1 sec for the progenitor mass range 10 − 10 3 M ⊙ , much larger than the naive estimation of the gravitational collapse time ∼ GM/c 3 ≃ 5 · 10 −6 M/M ⊙ sec, where G is Newton's constant, M is black hole mass, c is the speed of light. Observed durations of P-GRBs (Ruffini et al, 2009) of most energetic GRBs is of the order of several seconds. Main purpose of this paper is to outline a possibility of resolution of this tension considering different mechanisms of spreading of ultrarelativistically expanding shell.…”

Luminosity function of BATSE GRBs whose prompt emission is not dominated by the P-GRB

“…Within the Fireshell model [3] it is defined a "canonical" GRB bolometric light curve, formed by two physically distinct components: 1) the Proper-GRB (P-GRB), which is the flash emitted when the ultrarelativistically expanding e + e − -baryon plasma originating the GRB reaches transparency; and 2) the extended afterglow, which is the prolonged emission due to the interaction of the accelerated baryons, which constituted the fireshell baryon loading and have been left over after transparency, with the CircumBurst Medium (CBM) and which comprises a rising part, a peak and a decaying phase [11]. What is usually called "prompt emission" is actually formed by both the P-GRB and the rising part and the peak of the extended afterglow, while what is usually called "afterglow" is the decaying phase of the extended afterglow.…”

“…Obtaining GUSBAD "sanitized", spectral classes, E r p pk and < V /V max > We obtained the GUSBAD "sanitized" sample from the reduced version of GUSBAD (1319 GRBs), where we took out the sources whose peak luminosity are reached during the P-GRB phase; in this case we want to study only the GRBs whose peak fluxes was located in the extended afterglow, instead of the P-GRB [3]. Thus we excluded the sources with at least one of the following two characteristics: 1) with duration smaller than 2 seconds or 2) with duration greater than 10 seconds and peak flux occurring in the first two seconds.…”

“…In the Fireshell model, GRB prompt emission is formed by two phases each one due to a particular physical process: the P-GRB and the extended afterglow peak (Ruffini et al 2009 [3]). The first one is produced at the fireshell transparency, the second by the subsequent interaction between the optically thin fireshell and the circumburst medium (CBM).…”