Luminosity Functions of Gamma-Ray Burst Afterglows

Abstract

Aims: Use the standard fireball model to create virtual populations of gamma-ray burst afterglows and study their luminosity functions. Methods: We randomly vary the parameters of the standard fireball model to create virtual populations of afterglows. We use the luminosity of each burst at an observer's time of 1 day to create a luminosity function and compare our results with available observational data to assess the internal consistency of the standard fireball model. Results: We show that the luminosity functions can be described by a function similar to a log normal distribution with an exponential cutoff. The function parameters are frequency dependent but not very dependent on the model parameter distributions used to create the virtual populations. Comparison with observations shows that while there is good general agreement with the data, it is difficult to explain simultaneously the X-ray and optical data. Possible reasons for this are discussed and the most likely one is that the standard fireball model is incomplete and that decoupling of the X-ray and optical emission mechanism may be needed.

5 pages, 4 figures; accepted for publication in A&A

References in corpus (12)

• Beaming in Gamma-Ray Bursts: Evidence for a Standard Energy Reservoir
• Discovery of the X-Ray Afterglow of the Gamma-Ray Burst of February 28 1997
• Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data
• Signatures of Extragalactic Dust in pre-Swift GRB Afterglows
• Physical Parameters for the Afterglows of GRB 980703, 990123, 990510, and 991216 Determined from Modeling of Multi-Frequency Data
• HI column densities of z > 2 Swift gamma-ray bursts
• The clustering of the luminosities of optical afterglows of long Gamma Ray Bursts
• Jets, Structured Outflows, and Energy Injection in GRB Afterglows: Numerical Modelling
• Identification of Two categories of optically bright gamma-ray bursts
• Energy Injection in GRB Afterglow Models
• Afterglow Light Curves and Broken Power Laws: A Statistical Study
• Decay properties of the X-ray afterglows of Gamma-ray bursts

Cited by in corpus (5)

• The Afterglows of Swift-era Gamma-Ray Bursts. I. Comparing pre-Swift and Swift era Long/Soft (Type II) GRB Optical Afterglows
• The Swift Gamma-Ray Burst redshift distribution: selection biases and optical brightness evolution at high-z?
• Optical afterglow luminosities in the Swift epoch: confirming clustering and bimodality
• The detection efficiency of on-axis short gamma ray burst optical afterglows triggered by aLIGO/Virgo
• Are GRB optical afterglows relatively brighter at high z?