[vsnet-grb-info 21407] Fermi-GBM Observations During Four New GW-Detected BBH Mergers

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23506
SUBJECT: Fermi-GBM Observations During Four New GW-Detected BBH Mergers
DATE:    18/12/04 18:56:35 GMT
FROM:    Eric Burns at GSFC  <erickayserburns at gmail.com>

Four new binary black hole mergers detections by LIGO/Virgo have been
reported in GWTC-1, the first catalog of gravitational-wave transients [1].
We searched for coincident Fermi-GBM on-board triggers[2], sub-threshold
short gamma-ray burst candidates[3], and for transient using the targeted
search of Fermi-GBM data[4]. In no cases did we find significant gamma-ray
emission in the Fermi-GBM data. We report the GW localization probability
observed by Fermi-GBM (observing fraction) for each GW at event time:

GW                Observing Fraction
GW170729    88%
GW170809    78%
GW170818    100%
GW170823    0%  (Fermi was transiting the SAA)

The results of the observations around prior gravitational wave signals
have been previously published or are reported in GCN circulars.

We have searched for significant gamma-ray emission in Fermi-GBM around the
marginal triggers reported in GWTC-1 and found nothing of immediate
interest. The results here are preliminary. The final results and the
population-level analysis are part of on-going work between Fermi-GBM and
LIGO/Virgo. Upper limits may be presented in this work. The implications of
these non-detections on the candidate counterpart around GW150914 are the
subject of on-going work.

[1] https://arxiv.org/abs/1811.12907
[2] https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
[3] https://gcn.gsfc.nasa.gov/fermi_gbm_subthresh_archive.html
[4] http://iopscience.iop.org/article/10.1088/0067-0049/217/1/8/meta