Is the Afterglow of Gamma-Ray Burst GRB 021004 Unusual?

Dado, S.; Dar, Arnon; Rújula, A. De

doi:10.1086/374237

Cited by 10 publications

(12 citation statements)

References 29 publications

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“…In the context of the fireball model, the deviations in the case of GRB 021004 are interpreted as due to a variable external density (Lazzati et al 2002b), and for GRB 030329 they are interpreted as due to refreshed shocks from the inner engine (Granot et al 2003). We note that the cannonball model offers an alternative explanation for these observations (Dado et al 2002(Dado et al , 2003a. For GRB 030323, we only study the global properties of the light curve, and compare them to the light curve decay and spectral slope values as predicted by the fireball model (e.g.…”

Section: Photometrymentioning

confidence: 82%

The host of GRB 030323 at $\mathsf{\textit{z}=3.372}$: A very high column density DLA system with a low metallicity

Vreeswijk

Ellison

Ledoux

et al. 2004

A&A

201

185

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Abstract. We present photometry and spectroscopy of the afterglow of GRB 030323. VLT spectra of the afterglow show damped Lyα (DLA) absorption and low-and high-ionization lines at a redshift z = 3.3718 ± 0.0005. The inferred neutral hydrogen column density, log N(H i) = 21.90 ± 0.07, is larger than any (GRB-or QSO-) DLA H  column density inferred directly from Lyα in absorption. From the afterglow photometry, we derive a conservative upper limit to the host-galaxy extinction: A V < 0.5 mag. The iron abundance is [Fe/H] = −1.47 ± 0.11, while the metallicity of the gas as measured from sulphur is [S/H] = −1.26 ± 0.20. We derive an upper limit on the H 2 molecular fraction of 2N(H 2 )/(2N(H 2 ) + N(H i)) < ∼ 10 −6 . In the Lyα trough, a Lyα emission line is detected, which corresponds to a star-formation rate (not corrected for dust extinction) of roughly 1 M yr −1 . All these results are consistent with the host galaxy of GRB 030323 consisting of a low metallicity gas with a low dust content. We detect fine-structure lines of silicon, Si *, which have never been clearly detected in QSO-DLAs; this suggests that these lines are produced in the vicinity of the GRB explosion site. Under the assumption that these fine-structure levels are populated by particle collisions, we estimate the H  volume density to be n H i = 10 2 −10 4 cm −3 . HST/ACS imaging 4 months after the burst shows an extended AB(F606W) = 28.0 ± 0.3 mag object at a distance of 0. 14 (1 kpc) from the early afterglow location, which presumably is the host galaxy of GRB 030323.

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Section: Photometrymentioning

confidence: 82%

The host of GRB 030323 at $\mathsf{\textit{z}=3.372}$: A very high column density DLA system with a low metallicity

Vreeswijk

Ellison

Ledoux

et al. 2004

A&A

201

185

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“…The question is: Does this "observed" range correspond to the emission by a single CB? Two cases in which the answer is affirmative are: GRB 030329 (Dado et al 2003f), which we discuss in further detail in Appendix I, and GRB 021004 (Dado et al 2003c). These cases have various common properties: the GRB's γ-ray light curve has a very clear two-peak (two-CB) structure, as can be seen in 31); and the AG of both GRBs was "caught" very early: good measurements of it were taken before t ∼ 1 day.…”

Section: The Grb Energy Emitted By a Single Cbmentioning

confidence: 98%

Towards a complete theory of gamma-ray bursts

2004

Self Cite

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Gamma Ray Bursts (GRBs) are notorious for their diversity. Yet, they have a series of common features. The typical energy of their γ rays is a fraction of an MeV. The energy distributions are well described by a "Band spectrum", with "peak energies" spanning a surprisingly narrow range. The time structure of a GRB consists of pulses, superimposed or not, rising and decreasing fast. The number of photons in a pulse, the pulses' widths and their total energy vary within broad but specific ranges. Within a pulse, the energy spectrum softens with increasing time. The duration of a pulse decreases at higher energies and its peak intensity shifts to earlier time. Many other correlations between pairs of GRB observables have been identified. Last (and based on one measured event!) the γ-ray polarization is very large. A satisfactory theory of GRBs should naturally and very simply explain, among others, all these facts. We show that the "cannonball" (CB) model does it. In the CB model the process leading to the ejection of highly relativistic jetted CBs in core-collapse supernova (SN) explosions is akin to the one observed in quasars and microquasars. The prompt γ-ray emission -the GRB-is explained extremely well by inverse Compton scattering of light in the near environment of the SN by the electrons in the CBs' plasma. We have previously shown that the CB-model's description of GRB afterglows as synchrotron radiation from ambient electrons -swept in and accelerated within the CBs-is also simple, universal and very successful. The only obstacle still separating the CB model from a complete theory of GRBs is the theoretical understanding of the CBs' ejection mechanism in SN explosions. most dense star-burst regions, was found to be insufficient to explain the γ-ray fluence of the most powerful GRBs, such as GRB 990213. We shall see that, in the CB model, this problem -the dearth of "target" light-does not arise.In the CB model, long-duration GRBs are made by core-collapse supernovae (SNe). As we asserted in Dar & De Rújula (2000a) "the light from the SN shell is Compton upscattered to MeV energies, but its contribution to a GRB is sub-dominant". That assertion is correct: the light from the SN shell is too underluminous and too radially directed to generate GRBs of the observed fluence and individual-photon energy. With our collaborator Shlomo Dado, we have developed a very complete, simple and -we contend-extremely successful analysis of GRB AGs (Dado, Dar & De Rújula 2002a,b,c, 2003a. This thorough analysis has taught us that there should be another, much more intense and more isotropic, source of scattered light: the SN's "glory". The glory is the "echo" (or ambient) light from the SN, permeating the "wind-fed" circumburst density profile, previously ionized by the early extreme UV flash accompanying a SN explosion, or by the enhanced UV emission that precedes it. In Sections 2 and 3 we summarize the observations of pre-SN winds, early SN luminosities, and the UV flashes of SNe, to obtain the reference values of the v...

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“…These complex environments can produce very bright and fast declining early-time AGs [165,166], or strongly extinct the early AG [167], or even decelerate completely the CB, producing a 'dark GRB' [168].…”

Section: The Synchrotron Radiation "Afterglow"mentioning

confidence: 99%

“…The prompt ultraviolet-to-infrared AG depends critically on the complex density profile along the CB's trajectory and on the extinction along the line of sight. These complex environments can produce very bright and fast declining early-time AGs [165,166], or strongly extinct the early AG [167], or even decelerate completely the CB, producing a 'dark GRB' [168].…”

Section: The Synchrotron Radiation "Afterglow"mentioning

confidence: 99%

A theory of cosmic rays

Dar

Rújula

2008

Physics Reports

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We present a theory of non-solar cosmic rays (CRs) in which the bulk of their observed flux is due to a single type of CR source at all energies. The total luminosity of the Galaxy, the broken power-law spectra with their observed slopes, the position of the 'knee(s)' and 'ankle', and the CR composition and its variation with energy are all predicted in terms of very simple and completely 'standard' physics. The source of CRs is extremely 'economical': it has only one parameter to be fitted to the ensemble of all of the mentioned data. All other inputs are 'priors', that is, theoretical or observational items of information independent of the properties of the source of CRs, and chosen to lie in their pre-established ranges. The theory is part of a 'unified view of high-energy astrophysics' -based on the 'Cannonball' model of the relativistic ejecta of accreting black holes and neutron stars. The model has been extremely successful in predicting all the novel properties of Gamma Ray Bursts recently observed with help of the Swift satellite. If correct, this model is only lacking a satisfactory theoretical understanding of the 'cannon' that emits the cannonballs in catastrophic processes of accretion.

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Is the Afterglow of Gamma-Ray Burst GRB 021004 Unusual?

Cited by 10 publications

References 29 publications

The host of GRB 030323 at $\mathsf{\textit{z}=3.372}$: A very high column density DLA system with a low metallicity

The host of GRB 030323 at $\mathsf{\textit{z}=3.372}$: A very high column density DLA system with a low metallicity

Towards a complete theory of gamma-ray bursts

A theory of cosmic rays

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