Work

The Luminosity- E p Relation within Gamma-Ray Bursts and the Implications for Fireball Models

Year: 2004

Type: article

Abstract: Using a sample of 2408 time-resolved spectra for 91 BATSE gamma-ray bursts (GRBs) presented by Preece et al., we show that the relation between the isotropic-equivalent luminosity ( L iso ) and the peak energy ( E ) of the ν F ν spectrum in the cosmological rest frame, L iso ∝ E , holds within these bursts and also holds among these GRBs, assuming that the burst rate as a function of redshift is proportional to the star formation rate. The possible implications of this relation for the fireball models are discussed by defining a parameter ω ≡ ( L iso /10 52 ergs s -1 ) 0.5 /( E /200 keV). It is found that ω is narrowly clustered in 0.1-1. We constrain some parameters for both the internal shock and external shock models from the requirement of ω ~ 0.1-1, assuming that these model parameters are uncorrelated. The distributions of the parameters suggest that if the prompt gamma rays are produced from kinetic-energy-dominated internal shocks, they may be radiated from a region around R ~ 10 12 -10 13 cm (or Lorentz factor ~130-410) with a combined internal shock parameter ζ i ~ 0.1-1 during the prompt gamma-ray phase, which is consistent with the standard internal shock model; if the prompt gamma rays of these GRBs are radiated from magnetic-dissipation-dominated external shocks, the narrow cluster of ω requires σ ~ 1-470, Γ ~ 216-511, E ~ 10 51 -10 54 ergs, n ~ 0.5-470 cm -3 , and ζ e ~ 0.36-3.6, where σ is the ratio of the cold to hot luminosity components, Γ is the bulk Lorentz factor of the fireball, E is the total energy release in the gamma-ray band, n is the medium number density, and ζ e is a combined external shock parameter; these values are also in a good agreement with the fittings to the afterglow data. These results indicate that both the kinetic-energy-dominated internal shock model and the magnetic-dissipation-dominated external shock model can well interpret the L iso ∝ E relation and the value of ω.

Source: The Astrophysical Journal

DOI: 10.1086/421047

Authors: E. W. Liang, Z. G. Dai, X. F. Wu

Institutions: Guangxi University, Chinese Academy of Sciences, Yunnan Observatories, National Astronomical Observatories, Nanjing University

Language: English

Topic: Gamma-ray bursts and supernovae

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: bronze

Funders: National Natural Science Foundation of China, Guangxi University

Awards: G2717198908, γ射线暴的观测与理论研究, G5342354293