Classifying GRB 170817A/GW170817 in a Fermi duration–hardness plane

I. Horváth, B. G. Tóth, J. Hakkila, L. V. Tóth, L. G. Balázs, I. I. Rácz, S. Pintér, Z. Bagoly

Research output: Contribution to journalLetter

8 Citations (Scopus)

Abstract

GRB 170817A, associated with the LIGO-Virgo GW170817 neutron-star merger event, lacks the short duration and hard spectrum of a Short gamma-ray burst (GRB) expected from long-standing classification models. Correctly identifying the class to which this burst belongs requires comparison with other GRBs detected by the Fermi GBM. The aim of our analysis is to classify Fermi GRBs and to test whether or not GRB 170817A belongs—as suggested—to the Short GRB class. The Fermi GBM catalog provides a large database with many measured variables that can be used to explore gamma-ray burst classification. We use statistical techniques to look for clustering in a sample of 1298 gamma-ray bursts described by duration and spectral hardness. Classification of the detected bursts shows that GRB 170817A most likely belongs to the Intermediate, rather than the Short GRB class. We discuss this result in light of theoretical neutron-star merger models and existing GRB classification schemes. It appears that GRB classification schemes may not yet be linked to appropriate theoretical models, and that theoretical models may not yet adequately account for known GRB class properties. We conclude that GRB 170817A may not fit into a simple phenomenological classification scheme.

Original languageEnglish
Article number53
JournalAstrophysics and Space Science
Volume363
Issue number3
DOIs
Publication statusPublished - Mar 1 2018

Keywords

  • Astronomical databases: miscellaneous
  • Cosmology: miscellaneous
  • Cosmology: observations
  • Gamma-ray burst: general
  • Gamma-ray burst: individual: GRB170817A
  • Gamma-rays: general
  • Gravitational waves
  • Methods: data analysis
  • Methods: statistical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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