GCN Circular 27394
Subject
LIGO/Virgo S200316bj: Upper limits from Fermi-GBM Observations
Date
2020-03-17T03:24:48Z (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 S200316bj and using the initial bayestar.fits.gz,1 skymap, Fermi-GBM was observing 33.4% 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 S200316bj (GCN 27388). 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.
Part of the LVC localization region is behind the Earth for Fermi, located at RA=58.3, Dec=19.5 with a radius of 67.2 degrees. We therefore set upper limits on impulsive gamma-ray emission for the LVC localization region visible to Fermi at merger time. 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: 1.7 2.5 5.3
1.024 s: 0.4 0.8 1.8
8.192 s: 0.2 0.3 0.5
Assuming the median luminosity distance of 1222 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
------------------------------------
0.128s: 4.7 6.2 22.
1.024s: 1.1 2.0 7.5
8.192s: 0.5 0.7 2.2