English

Variation of the Amati Relation with the Cosmological Redshift: a Selection Effect or an Evolution Effect?

Astrophysics 2009-06-23 v1

Abstract

Because of the limit in the number of gamma-ray bursts (GRBs) with available redshifts and spectra, all current investigations on the correlation among GRB variables use burst samples with redshifts that span a very large range. The evolution and selection effects have thus been ignored, which might have important influence on the results. In this Letter, we divide the 48 long-duration GRBs in Amati (2006, 2007) into four groups with redshift from low to high, each group contains 12 GRBs. Then we fit each group with the Amati relation logE\iso=a+blogE\p\log E_\iso = a + b \log E_\p, and check if the parameters aa and bb evolve with the GRB redshift. We find that aa and bb vary with the mean redshift of the GRBs in each group systematically and significantly. Monte-Carlo simulations show that there is only 4\sim 4 percent of chance that the variation is caused by the selection effect arising from the fluence limit. Hence, our results may indicate that GRBs evolve strongly with the cosmological redshift.

Keywords

Cite

@article{arxiv.0704.3128,
  title  = {Variation of the Amati Relation with the Cosmological Redshift: a Selection Effect or an Evolution Effect?},
  author = {Li-Xin Li},
  journal= {arXiv preprint arXiv:0704.3128},
  year   = {2009}
}
R2 v1 2026-06-21T08:21:29.354Z