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GRB 210217A: a short or a long GRB?

2022; Springer Nature; Volume: 43; Issue: 2 Linguagem: Inglês

10.1007/s12036-022-09822-x

0973-7758

Dimple Dimple, Kuntal Misra, Ankur Ghosh, K. G. Arun, Rahul Gupta, Amit Kumar, L. Resmi, S. B. Pandey, Lallan Yadav,

Astronomy and Astrophysical Research

Gamma-ray bursts are traditionally classified as short and long bursts based on their $$T_{90}$$ value (the time interval during which an instrument observes 5% to 95% of gamma-ray/hard X-ray fluence). However, $$T_{90}$$ is dependent on the detector sensitivity and the energy range in which the instrument operates. As a result, different instruments provide different values of $$T_{90}$$ for a burst. GRB 210217A is detected with different duration by Swift and Fermi. It is classified as a long/soft GRB by Swift-BAT with a $$T_{90}$$ value of 3.76 s. On the other hand, the sub-threshold detection by Fermi-GBM classified GRB 210217A as a short/hard burst with a duration of 1.024 s. We present the multi-wavelength analysis of GRB 210217A (lying in the overlapping regime of long and short GRBs) to identify its actual class using multi-wavelength data. We utilized the $$T_{90}$$ -hardness ratio, $$T_{90}-E_{p}$$ and $$T_{90}-t_\mathrm{mvts}$$ distributions of the GRBs to find the probability of GRB 210217A being a short GRB. Further, we estimated the photometric redshift of the burst by fitting the joint XRT/UVOT SED and placed the burst in the Amati plane. We found that GRB 210217A is an ambiguous burst showing properties of both short and long class of GRBs.