GRB 060218 and GRBs associated with supernovae Ib/c

Dainotti, Maria Giovanna; Bernardini, M. G.; Bianco, C. L.; Caito, Letizia; Guida, R.; Ruffini, Remo

doi:10.1051/0004-6361:20078068

Cited by 36 publications

(67 citation statements)

References 38 publications

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“…We recall that the fireshell model (Damour & Ruffini 1975;Ruffini et al 2000Ruffini et al , 2010Ruffini 2001) is an alternative to the Fireball model, first proposed by Cavallo & Rees (1978), Goodman (1986) and Paczynsky (1986). We assume, within the fireshell model, that all GRBs originate from the gravitational collapse of a star approaching asymptotically the formation of a Kerr-Newmann BH (Wiltshire et al 2009).…”

Section: Analysis Of Episode 2 In the Fireshell Modelmentioning

confidence: 99%

GRB 110709B in the induced gravitational collapse paradigm

Penacchioni

Ruffini

Bianco

et al. 2013

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Context. Gamma-ray burst (GRB) 110709B is the first source for which Swift-BAT was triggered twice, with a time separation of ∼10 min. The first emission (called here episode 1) lasted from 40 s before the first trigger time until 60 s after it. The second emission (hereafter episode 2) lasted from 35 s before the second trigger time until 100 s after it. These features reproduce those of GRB 090618, which has recently been interpreted within the induced gravitational collapse (IGC) paradigm. In line with this paradigm, we assume the progenitor to be a close binary system composed of the core of an evolved star and a neutron star (NS). The evolved star explodes as a supernova (SN) and ejects material that is partially accreted by the NS. We identify this process with episode 1. The accretion process accumulates more than the critical mass of the NS, which gravitationally collapses into a black hole (BH). This process leads to the GRB emission, episode 2. The two trigger episodes have for the first time provided the possibility to cover the X-ray emission observed by XRT both prior to and during the prompt phase of GRB 110709B. Aims. We analyze the spectra and time variability of episodes 1 and 2 and compute the relevant parameters of the binary progenitor, as well as the astrophysical parameters both in the SN and the GRB phase in the IGC paradigm. Methods. We performed a time-resolved spectral analysis of episode 1 by fitting the spectrum with a blackbody (BB) plus a power-law (PL) spectral model. From the BB fluxes and temperatures of episode 1 and the luminosity distance d L , we evaluated the evolution with time of the radius of the BB emitter, associated here to the evolution of the SN ejecta. We analyzed episode 2 within the fireshell model, identifying the proper GRB (P-GRB) and simulating the light curve and spectrum. We established the redshift to be z = 0.75, following the phenomenological methods described in the literature, and our analysis of the late X-ray afterglow. It is most remarkable that the determination of the cosmological redshift on the basis of scaling the late X-ray afterglow, which was already verified in GRB 090618 and GRB 101023, is again verified by this analysis. Results. We find for episode 1 a temperature of the BB component that evolves with time following a broken PL, with the slope of the PL at early times α = 0 (constant function) and the slope of the PL at late times β = −4 ± 2. The break occurs at t = 41.21 s. The total energy of episode 1 is E (1) iso = 1.42 × 10 53 erg. The total energy of episode 2 is E (2) iso = 2.43 × 10 52 erg. We find at transparency a Lorentz factor Γ ∼ 1.73 × 10 2 , laboratory radius of 6.04 × 10 13 cm, P-GRB observed temperature kT P−GRB = 12.36 keV, baryon load B = 5.7 × 10 −3 and P-GRB energy of E P−GRB = 3.44 × 10 50 erg. We find a remarkable coincidence of the cosmological redshift by scaling the XRT data and with three other phenomenological methods. Conclusions. We interpret GRB 110709B as a member of the IGC sources, together with G...

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Section: Analysis Of Episode 2 In the Fireshell Modelmentioning

confidence: 99%

GRB 110709B in the induced gravitational collapse paradigm

Penacchioni

Ruffini

Bianco

et al. 2013

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“…Typical values of R ranges between 10 −10 and 10 −6 (see e.g. Bernardini et al 2007Bernardini et al , 2005Caito et al 2009Caito et al , 2010Dainotti et al 2007;Ruffini et al 2006).…”

Section: The Fireshell Modelmentioning

confidence: 99%

On the nature of GRB 050509b: a disguised short GRB

Barros¹,

Amati²,

Bernardini³

et al. 2011

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Context. GRB 050509b, detected by the Swift satellite, is the first case where an X-ray afterglow has been observed associated with a short gamma-ray burst (GRB). Within the fireshell model, the canonical GRB light curve presents two different components: the proper-GRB (P-GRB) and the extended afterglow. Their relative intensity is a function of the fireshell baryon loading parameter B and of the CircumBurst Medium (CBM) density (n CBM ). In particular, the traditionally called short GRBs can be either "genuine" short GRBs (with B 10 −5 , where the P-GRB is energetically predominant) or "disguised" short GRBs (with B 3.0 × 10 −4 and n CBM 1, where the extended afterglow is energetically predominant). Aims. We verify whether GRB 050509b can be classified as a "genuine" short or a "disguised" short GRB, in the fireshell model. Methods. We investigate two alternative scenarios. In the first, we start from the assumption that this GRB is a "genuine" short burst.In the second attempt, we assume that this GRB is a "disguised" burst. Results. If GRB 050509b were a genuine short GRB, there should initially be very hard emission, which is ruled out by the observations. The analysis that assumes that this is a disguised short GRB is compatible with the observations. The theoretical model predicts a value of the extended afterglow energy peak that is consistent with the Amati relation. Conclusions. GRB 050509b cannot be classified as a "genuine" short GRB. The observational data are consistent with a "disguised" short GRB classification, i.e., a long burst with a weak extended afterglow "deflated" by the low density of the CBM. We expect that all short GRBs with measured redshifts are disguised short GRBs because of a selection effect: if there is enough energy in the afterglow to measure the redshift, then the proper GRB must be less energetic than the afterglow. The Amati relation is found to be fulfilled only by the extended afterglow excluding the P-GRB.

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“…This second parameter takes into account the CBM filamentary structure (Ruffini et al 2004) and the possible occurrence of fragmentation in the shell (Dainotti et al 2007). The emission from the baryonic matter shell is spherically symmetric.…”

Section: Brief Summary Of the Fireshell Modelmentioning

confidence: 99%

GRB 071227: an additional case of adisguisedshort burst

Caito¹,

Amati

Bernardini

et al. 2010

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Context. Observations of gamma-ray bursts (GRBs) have shown an hybridization between the two classes of long and short bursts. In the context of the fireshell model, the GRB light curves are formed by two different components: the proper GRB (P-GRB) and the extended afterglow. Their relative intensity is linked to the fireshell baryon loading B. The GRBs with P-GRB predominance are the short ones, the remainders are long. A new family of disguised short bursts has been identified: long bursts with a protracted low instantaneous luminosity due to a low density CircumBurst Medium (CBM). In the 15-150 keV energy band GRB 071227 exhibits a short duration (about 1.8 s) spike-like emission followed by a very soft extended tail up to one hundred seconds after the trigger. It is a faint (E iso = 5.8 × 10 50 ) nearby GRB (z = 0.383) that does not have an associated type Ib/c bright supernova (SN). For these reasons, GRB 071227 has been classified as a short burst not fulfilling the Amati relation holding for long burst. Aims. We check the classification of GRB 071227 provided by the fireshell model. In particular, we test whether this burst is another example of a disguised short burst, after GRB 970228 and GRB 060614, and, for this reason, whether it fulfills the Amati relation. Methods. We simulate GRB 071227 light curves in the Swift BAT 15-50 keV bandpass and in the XRT (0.3-10 keV) energy band within the fireshell model. Results. We perform simulations of the tail in the 15-50 keV bandpass, as well as of the first part of the X-ray afterglow. This infers that: E e ± tot = 5.04 × 10 51 erg, B = 2.0 × 10 −4 , E P−GRB /E aft ∼ 0.25, and n cbm = 3.33 particles cm −3 . These values are consistent with those of "long duration" GRBs. We interpret the observed energy of the first hard emission by identifying it with the P-GRB emission. The remaining long soft tail indeed fulfills the Amati relation. Conclusions. Previously classified as a short burst, GRB 071227 on the basis of our analysis performed in the context of the fireshell scenario represents another example of a disguised short burst, after GRB 970228 and GRB 060614. Further confirmation of this result is that the soft tail of GRB 071227 fulfills the Amati relation.

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GRB 060218 and GRBs associated with supernovae Ib/c

Cited by 36 publications

References 38 publications

GRB 110709B in the induced gravitational collapse paradigm

GRB 110709B in the induced gravitational collapse paradigm

On the nature of GRB 050509b: a disguised short GRB

GRB 071227: an additional case of adisguisedshort burst

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