Unveiling the progenitors of a population of likely peculiar GRBs

Fuente: arXiv
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Autores principales: Zhu, Si-Yuan, Tam, Pak-Hin Thomas
Formato: Preprint
Publicado: 2024
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author Zhu, Si-Yuan
Tam, Pak-Hin Thomas
author_facet Zhu, Si-Yuan
Tam, Pak-Hin Thomas
contents Traditionally, gamma-ray bursts (GRBs) are classified as long and short GRBs, with $T_{90} = 2$ s being the threshold duration. Generally, long-duration GRBs (LGRBs, $T_{90}>2$ s) are associated with the collapse of massive stars, and short-duration (SGRBs, $T_{90}<2$ s) are associated with the compact binary mergers involving at least one neutron star. However, the existence of a population of so-called ``peculiar GRBs", i.e., LGRBs originating from mergers, or long Type I GRBs, and SGRBs originating from collapsars, or short Type II GRBs, have challenged the traditional paradigm of GRB classification. Finding more peculiar GRBs may help to give us more insight into this issue. In this work, we analyze the properties of machine learning identified long Type I GRBs and short Type II GRBs candidates, long GRBs-I and short GRBs-II (the so-called ``peculiar GRBs"). We find that long GRBs-I almost always exhibit properties similar to Type I, which suggests that the merger may indeed produce GRBs with $T_{90}>2$ s. Furthermore, according to the probability given by the redshift distribution, short GRBs-II almost exhibit properties similar to Type II. This suggests that the populations of short Type II GRBs are not scarce and that they are hidden in a large number of samples without redshifts, which is unfavorable to the interpretation that the jet progression leads to a missed main emission.
format Preprint
id arxiv_https___arxiv_org_abs_2409_19719
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Unveiling the progenitors of a population of likely peculiar GRBs
Zhu, Si-Yuan
Tam, Pak-Hin Thomas
High Energy Astrophysical Phenomena
Traditionally, gamma-ray bursts (GRBs) are classified as long and short GRBs, with $T_{90} = 2$ s being the threshold duration. Generally, long-duration GRBs (LGRBs, $T_{90}>2$ s) are associated with the collapse of massive stars, and short-duration (SGRBs, $T_{90}<2$ s) are associated with the compact binary mergers involving at least one neutron star. However, the existence of a population of so-called ``peculiar GRBs", i.e., LGRBs originating from mergers, or long Type I GRBs, and SGRBs originating from collapsars, or short Type II GRBs, have challenged the traditional paradigm of GRB classification. Finding more peculiar GRBs may help to give us more insight into this issue. In this work, we analyze the properties of machine learning identified long Type I GRBs and short Type II GRBs candidates, long GRBs-I and short GRBs-II (the so-called ``peculiar GRBs"). We find that long GRBs-I almost always exhibit properties similar to Type I, which suggests that the merger may indeed produce GRBs with $T_{90}>2$ s. Furthermore, according to the probability given by the redshift distribution, short GRBs-II almost exhibit properties similar to Type II. This suggests that the populations of short Type II GRBs are not scarce and that they are hidden in a large number of samples without redshifts, which is unfavorable to the interpretation that the jet progression leads to a missed main emission.
title Unveiling the progenitors of a population of likely peculiar GRBs
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2409.19719