Fermi GBM Observations of GRB 150101B: A Second Nearby Event with a Short Hard Spike and a Soft Tail

TL;DR

This paper reanalyzes Fermi GBM data of GRB 150101B, revealing a two-component structure similar to GRB 170817A, suggesting the soft tail is common in nearby short gamma-ray bursts and can aid in identifying kilonovae.

Contribution

It demonstrates that GRB 150101B has a two-component structure similar to GRB 170817A, indicating the soft tail may be a common feature in nearby short gamma-ray bursts.

Findings

GRB 150101B has a short hard spike and a soft tail.

The soft tail is likely common in nearby short GRBs.

GRB 150101B can be modeled as an on-axis version of GRB 170817A.

Abstract

In light of the joint multimessenger detection of a binary neutron star merger as the gamma-ray burst GRB 170817A and in gravitational waves as GW170817, we reanalyze the Fermi Gamma-ray Burst Monitor data of one of the closest short gamma-ray bursts: GRB 150101B. We find this burst is composed of a short hard spike followed by a comparatively long soft tail. This apparent two-component nature is phenomenologically similar to that of GRB 170817A. While GRB 170817A was distinct from the previously known population of short gamma-ray bursts in terms of its prompt intrinsic energetics, GRB 150101B is not. Despite these differences, GRB 150101B can be modeled as a more on-axis version of GRB 170817A. Identifying a similar signature in two of the closest short gamma-ray bursts suggests the soft tail is common, but generally undetectable in more distant events. If so, it will be possible to identify nearby short gamma-ray bursts from the prompt gamma-ray emission alone, aiding the search for kilonovae.