Luminosity function of GRBs
1
Harish-chandra Research Institute, Jhusi Road, Allahabad 211 019, India e-mail: sethi@mri.ernet.in
2
Indian Institute of Astrophysics, Sarjapur Road, Bangalore 560 034, India e-mail: bhargavi@iiap.ernet.in
Corresponding author: S. Sethi, sethi@mri.ernet.in
Received:
12
February
2001
Accepted:
29
June
2001
We attempt to constrain the luminosity function of
Gamma Ray Bursts (GRBs) from the observed number count-flux
relation and the afterglow redshift data. We assume three classes of
luminosity functions for our analysis: (a) Log-normal distribution,
(b) Schechter distribution, and (c) Scale-free distribution.
We assume several models of the evolution of the GRB population
for each luminosity function.
Our analysis shows that: (a) log-normal is the only luminosity function
that is compatible with both the observations. This result is independent
of the GRB evolution model, (b) for log-normal function, the
average photon luminosity L0 and the width of the luminosity function
σ that are compatible with both the observations fall in the
range: 
and 
, (c) the agreement of observations with other
luminosity functions requires the GRB population to evolve more strongly
than the evolution of the star-formation rate of the universe.
Key words: gamma rays: bursts / cosmology: observations
© ESO, 2001