Search for cosmological time dilation from gammaray bursts  a 2021 status update
Abstract
We carry out a search for signatures of cosmological time dilation in the light curves of Gamma Ray Bursts (GRBs), detected by the Neil Gehrels Swift Observatory. For this purpose, we calculate two different durations (T _{50} and T _{90}) for a sample of 247 GRBs in the fixed rest frame energy interval of 140350 keV, similar to a previous work [1]. We then carry out a power lawbased regression analysis between the durations and redshifts. This search is done using both the unbinned as well as the binned data, where both the weighted mean and the geometric mean was used. For each analysis, we also calculate the intrinsic scatter to determine the tightness of the relation. We find that the weighted meanbased binned data for long GRBs and the geometric meanbased binned data is consistent with the cosmological time dilation signature, whereas the analyses using unbinned durations show a very large scatter. We also make our analysis codes and the procedure for obtaining the light curves and estimation of T _{50}/T _{90} publicly available.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 February 2022
 DOI:
 10.1088/14757516/2022/02/010
 arXiv:
 arXiv:2108.00395
 Bibcode:
 2022JCAP...02..010S
 Keywords:

 gamma ray burst experiments;
 gamma ray bursts theory;
 Astrophysics  High Energy Astrophysical Phenomena;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 27 pages, 18 figures. Accepted for publication in JCAP