TY - JOUR

T1 - An Unambiguous Separation of Gamma-Ray Bursts into Two Classes from Prompt Emission Alone

AU - Jespersen, Christian K.

AU - Severin, Johann B.

AU - Steinhardt, Charles L.

AU - Vinther, Jonas

AU - Fynbo, Johan P. U.

AU - Selsing, Jonatan

AU - Watson, Darach

PY - 2020/6/1

Y1 - 2020/6/1

N2 - The duration of a gamma-ray burst (GRB) is a key indicator of its physical origin, with long bursts perhaps associated with the collapse of massive stars and short bursts with mergers of neutron stars. However, there is substantial overlap in the properties of both short and long GRBs and neither duration nor any other parameter so far considered completely separates the two groups. Here we unambiguously classify every GRB using a machine-learning dimensionality reduction algorithm, t-distributed stochastic neighborhood embedding, providing a catalog separating all Swift GRBs into two groups. Although the classification takes place only using prompt emission light curves, every burst with an associated supernova is found in the longer group and bursts with kilonovae in the short, suggesting along with the duration distributions that these two groups are truly long and short GRBs. Two bursts with a clear absence of a supernova belong to the longer class, indicating that these might have been direct-collapse black holes, a proposed phenomenon that may occur in the deaths of more massive stars.

AB - The duration of a gamma-ray burst (GRB) is a key indicator of its physical origin, with long bursts perhaps associated with the collapse of massive stars and short bursts with mergers of neutron stars. However, there is substantial overlap in the properties of both short and long GRBs and neither duration nor any other parameter so far considered completely separates the two groups. Here we unambiguously classify every GRB using a machine-learning dimensionality reduction algorithm, t-distributed stochastic neighborhood embedding, providing a catalog separating all Swift GRBs into two groups. Although the classification takes place only using prompt emission light curves, every burst with an associated supernova is found in the longer group and bursts with kilonovae in the short, suggesting along with the duration distributions that these two groups are truly long and short GRBs. Two bursts with a clear absence of a supernova belong to the longer class, indicating that these might have been direct-collapse black holes, a proposed phenomenon that may occur in the deaths of more massive stars.

KW - Gamma-ray bursts

KW - Astronomy data analysis

KW - Astronomy data visualization

KW - Light curve classification

KW - Supernovae

KW - High energy astrophysics

KW - SUPERNOVAE

U2 - 10.3847/2041-8213/ab964d

DO - 10.3847/2041-8213/ab964d

M3 - Letter

VL - 896

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

SN - 2041-8205

IS - 2

M1 - 20

ER -