2020/09/30 by G. P. Srinivasaragavan, Gokul Prem Srinivasaragavan, M. G. Dainotti +13
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #CCD and CMOS Imaging Sensors #Closure (psychology) #Fundamental plane (elliptical galaxies) #Gamma-ray burst #Gamma-ray bursts and supernovae #Luminosity #Observatory #Plane (geometry) #Redshift #Swift #astro-ph.HE
paper · pdf · doi:10.3847/1538-4357/abb702
Accepted in ApJ, 24 pages, 10 figures; modified order of co-author list; updated Acknowledgements and journal proofs; updated journal acceptance Information
openalex created_date 2020/09/21 · openalex publication_date 2020/10/28 · arxiv created 2020/11/18 · arxiv updated 2020/11/20 · openalex updated_date 2026/08/06
Abstract Gamma-ray Bursts (GRBs) are the most explosive phenomena in the universe after the big bang. A large fraction of GRB lightcurves (LCs) shows X-ray plateaus. We perform the most comprehensive analysis of all GRBs (with known and unknown redshifts) with plateau emission observed by The Neil Gehrels Swift Observatory from its launch until 2019 August. We fit 455 LCs showing a plateau and explore whether these LCs follow closure relations, relations between the temporal and spectral indices of the afterglow, corresponding to two distinct astrophysical environments and cooling regimes within the external forward shock (ES) model, and find that the ES model works for the majority of cases. The most favored environments are a constant-density interstellar or wind medium with slow cooling. We also confirm the existence of the fundamental plane relation between the rest-frame time and luminosity at the end of the plateau emission and the peak prompt luminosity for this enlarged sample, and test this relation on groups corresponding to the astrophysical environments of our known redshift sample. The plane becomes a crucial discriminant corresponding to these environments in terms of the best-fitting parameters and dispersions. Most GRBs for which the closure relations are fulfilled with respect to astrophysical environments have an intrinsic scatter σ compatible within 1 σ of that of the “Gold” GRBs, a subset of long GRBs with relatively flat plateaus. We also find that GRBs satisfying closure relations indicating a fast cooling regime have a lower σ than ever previously found in literature.