V. Connaughton, Huntsville Program Office
E. Burns, The University of Alabama in Huntsville
A. Goldstein, NASA Marshall Space Flight Center
L. Blackburn, Harvard-Smithsonian Center for Astrophysics
M. S. Briggs, The University of Alabama in Huntsville
B. B. Zhang, Center for Space Plasma and Aeronomic Research
J. Camp, NASA Goddard Space Flight Center
N. Christensen, Carleton College, USA
C. M. Hui, NASA Marshall Space Flight Center
P. Jenke, Center for Space Plasma and Aeronomic Research
T. Littenberg, Huntsville Program Office
J. E. McEnery, NASA Goddard Space Flight Center
J. Racusin, NASA Goddard Space Flight Center
P. Shawhan, University of Maryland, College Park
L. Singer, NASA Goddard Space Flight Center
J. Veitch, University of Birmingham
C. A. Wilson-Hodge, NASA Marshall Space Flight Center
P. N. Bhat, Center for Space Plasma and Aeronomic Research
E. Bissaldi, Istituto Nazionale di Fisica Nucleare, Sezione di Bari
W. Cleveland, Huntsville Program Office
G. Fitzpatrick, Center for Space Plasma and Aeronomic Research
M. M. Giles, Jacobs Technology Inc.
M. H. Gibby, Jacobs Technology Inc.
A. Von Kienlin, Max Planck Institute for Extraterrestrial Physics
R. M. Kippen, Los Alamos National Laboratory
S. McBreen, University College Dublin
B. Mailyan, Center for Space Plasma and Aeronomic Research
C. A. Meegan, Center for Space Plasma and Aeronomic Research
W. S. Paciesas, Huntsville Program Office
R. D. Preece, The University of Alabama in Huntsville
O. J. Roberts, University College Dublin
L. Sparke, National Aeronautics and Space Administration
M. Stanbro, The University of Alabama in Huntsville

Document Type

Article

Publication Date

7-20-2016

Abstract

With an instantaneous view of 70% of the sky, the Fermi Gamma-ray Burst Monitor (GBM) is an excellent partner in the search for electromagnetic counterparts to gravitational-wave (GW) events. GBM observations at the time of the Laser Interferometer Gravitational-wave Observatory (LIGO) event GW150914 reveal the presence of a weak transient above 50 keV, 0.4 s after the GW event, with a false-alarm probability of 0.0022 (2.9σ). This weak transient lasting 1 s was not detected by any other instrument and does not appear to be connected with other previously known astrophysical, solar, terrestrial, or magnetospheric activity. Its localization is ill-constrained but consistent with the direction of GW150914. The duration and spectrum of the transient event are consistent with a weak short gamma-ray burst (GRB) arriving at a large angle to the direction in which Fermi was pointing where the GBM detector response is not optimal. If the GBM transient is associated with GW150914, then this electromagnetic signal from a stellar mass black hole binary merger is unexpected. We calculate a luminosity in hard X-ray emission between 1 keV and 10 MeV of erg s-1. Future joint observations of GW events by LIGO/Virgo and Fermi GBM could reveal whether the weak transient reported here is a plausible counterpart to GW150914 or a chance coincidence, and will further probe the connection between compact binary mergers and short GRBs.

Publication Source (Journal or Book title)

Astrophysical Journal Letters

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