GCN Circular 24112
Subject
LIGO/Virgo S190412m: Fermi-GBM Observations
Date
2019-04-12T18:52:52Z (5 years ago)
From
Adam Goldstein at Fermi-GBM, USRA <adam.michael.goldstein@gmail.com>
A. Goldstein (USRA) reports on behalf of the Fermi-GBM Team and the
GBM-LIGO/Virgo group
For S190412m, and using the initial BAYESTAR skymap, Fermi-GBM was
observing 99.8% of the localization probability region at event time.
There was no Fermi-GBM onboard trigger around the event time of the
LIGO/Virgo detection of a GW trigger (GCN 24098). An automated, blind
search for short gamma-ray bursts below the onboard triggering threshold in
Fermi-GBM also identified no counterpart candidates. The GBM targeted
search, the most sensitive, coherent search for GRB-like signals, was run
from +/-30 s around merger time, and also identified no counterpart
candidates.
We therefore set upper limits on impulsive gamma-ray emission considering
the 90% credible region of the GW localization. Using the representative
soft, normal, and hard GRB-like spectral templates described in
arXiv:1612.02395, we set the following 3 sigma flux upper limits over
10-1000 keV (in units of 10^-7 erg/s/cm^2):
Timescale Soft Normal Hard
------------------------------------
0.1 s: 4.7-5.7 9.1-10 25-27
1.0 s: 1.5-1.8 2.8-3.2 7.4-7.9
10 s: 0.5-0.6 0.9-1.0 2.3-2.4
Assuming the mean luminosity distance of 812 Mpc from the GW detection, we
estimate intrinsic luminosity upper limits of (0.6-6.9)E49 erg/s for the
soft template, (1.0-11)E49 erg/s for the normal template, and (4.2-50)E49
erg/s for the hard template over the 1 keV-10 MeV energy range.