GCN Circular 25886
Subject
LIGO/Virgo S190930s: Upper limits from Fermi-GBM Observations
Date
2019-09-30T19:52:14Z (5 years ago)
From
Joshua Wood at MSFC/Fermi-GBM <joshua.r.wood@nasa.gov>
J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group
For S190930s and using the initial bayestar.fits.gz skymap, Fermi-GBM was observing 62.2% of the localization probability at event time.
There was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo detection of GW trigger S190930s (GCN 25871). 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. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV, weighted by GW localization probability (in units of 10^-7 erg/s/cm^2):
Timescale Soft Normal Hard
------------------------------------
0.128 s: 5.7 6.6 10.
1.024 s: 1.6 2.2 3.5
8.192 s: 0.6 0.7 1.0
Assuming the median luminosity distance of 752 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^49 erg/s):
Timescale Soft Normal Hard
------------------------------------
0.128 s: 5.94 6.29 15.8
1.024 s: 1.67 2.10 5.53
8.192 s: 0.62 0.65 1.58