Cosmological gamma-ray bursts

Fenimore, E.; Epstein, Richard I.; Ho, Cheng; Int-Zand, J. J. M.

doi:10.2172/212549

Cited by 89 publications

(121 citation statements)

References 1 publication

Supporting

Mentioning

112

Contrasting

Order By: Relevance

“…burst, so the value of t A should lie between 15 s and 65 s, and therefore we can get the initial Lorentz factor 250 < γ 0 < 900, which is consistent with the lower limit estimates base on the γ-γ attenuation calculation (Fenimore et al 1993). …”

Section: Fitting the Afterglow Of Grb 021211supporting

confidence: 87%

The afterglow of GRB 021211: Another case of reverse shock emission

Wei

2003

A&A

View full text Add to dashboard Cite

Abstract. GRB 021211 was first detected by HETE II and its early afterglow has been observed. There is a break in its afterglow light curve at about 12 min after the bursts, before the break the optical flux decays with a power-law index of about −1.6, while at late time the power-law slope is about −1 . Here we will show that the afterglow light curve of GRB 021211 can be explained within the framework of the standard fireball model. We show that the afterglow emission before the break time is the contribution of the emission from both the reverse shock and the forward shock, while the afterglow emission after the break time is mainly due to the forward shock emission. From the fitting we can give constraints on the parameters: the initial Lorentz factor 250 ≤ γ 0 ≤ 900, and the surrounding medium density n ≥ 1.6 × 10 −3 atoms cm −3 . We propose that since the values of B and e are somewhat smaller for GRB 021211, so the peak energy of the reverse shock emission is well below the optical band, and thus it is substantially fainter than 990123 at similar epochs. Also we suggest that such a break might be a common feature in early optical afterglows.

show abstract

Section: Fitting the Afterglow Of Grb 021211supporting

confidence: 87%

The afterglow of GRB 021211: Another case of reverse shock emission

Wei

2003

A&A

View full text Add to dashboard Cite

show abstract

“…Together this leads to a decrease in the estimated optical depth by a factor of Γ 2+2α , where α ∼ 2 is the spectral index, namely the exponent of the photon number distribution. Various estimates 20,21,22,23 , of the Lorentz factor Γ based on the compactness problem lead to comparable values, Γ ≥ 100, (see 23 for a critical review). Today we have independent direct observational evidence for such ultra-relativistic motion.…”

Section: The Compactness Problem and Ultra-relativistic Motionmentioning

confidence: 99%

Gamma-Ray Bursts - A Primer for Relativists

Piran¹

2002

General Relativity and Gravitation

View full text Add to dashboard Cite

Gamma-Ray Bursts (GRBs) -short bursts of 100-1MeV photons arriving from random directions in the sky are probably the most relativistic objects discovered so far. Still, somehow they did not attract the attention of the relativistic community. In this short review I discuss briefly GRB observations and show that they lead us to the fireball model -GRBs involve macroscopic relativistic motion with Lorentz factors of a few hundred or more. I show that GRB sources involve, most likely, new born black holes, and their progenitors are Supernovae or neutron star mergers. I show that both GRB progenitors and the process of GRB itself produce gravitational radiation and I consider the possibility of detecting this emission. Finally I show that GRBs could serve as cosmological indicators that could teach us about the high redshift (z ≈ 5 − 15) dark ages of the universe.

show abstract

“…However, the Lorentz factor of the outflow is not an observable quantity. Several methods have been proposed to estimate the Lorentz factor (Γ) base on different hypothesis or fireball models: a lower limit can be obtained by requiring the Lorentz factor is large enough to make the observed most energetic photon not to annihilate (Krolik & Pier 1991;Fenimore et al 1993;Woods & Loeb 1995;Baring & Harding 1997). If cutoffs are observed on the high end of the spectra of prompt emissions, the exact values of Lorentz factor rather than lower limits can be derived by assuming the optical depth equals unity for photons with cutoff energies (Lithwick & Sari 2001;Ackermann et al 2011;Tang et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Bulk Lorentz Factors of Outflow Material: Lessons Learned from the Extremely Energetic Outburst GRB 160625B

Wang

Zhang

et al. 2017

ApJ

View full text Add to dashboard Cite

GRB 160625B is an extremely-bright outburst with well-monitored afterglow emission. The geometrycorrected energy is high up to ∼ 5.2 × 10 52 erg or even ∼ 8 × 10 52 erg, rendering it the most energetic GRB prompt emission recorded so far. We analyzed the time-resolved spectra of the prompt emission and found that in some intervals there were likely thermal-radiation components and the high energy emission were characterized by significant cutoff. The bulk Lorentz factors of the outflow material are estimated accordingly. We found out that the Lorentz factors derived in the thermal-radiation model are consistent with the luminosity-Lorentz factor correlation found in other bursts as well as in GRB 090902B for the time-resolved thermal-radiation components. While the spectral cutoff model yields much lower Lorentz factors that are in tension with the constraints set by the electron pair Compoton scattering process. We then suggest that these spectral cutoffs are more likely related to the particle acceleration process and that one should be careful in estimating the Lorentz factors if the spectrum cuts at a rather low energy (e.g., ∼ tens MeV). The nature of the central engine has also been discussed and a stellar-mass black hole is favored.

show abstract

Cosmological gamma-ray bursts

Cited by 89 publications

References 1 publication

The afterglow of GRB 021211: Another case of reverse shock emission

The afterglow of GRB 021211: Another case of reverse shock emission

Gamma-Ray Bursts - A Primer for Relativists

Evaluating the Bulk Lorentz Factors of Outflow Material: Lessons Learned from the Extremely Energetic Outburst GRB 160625B

Contact Info

Product

Resources

About