GCN Circular 26774
Subject
LIGO/Virgo S200115j: Upper limits from Fermi-GBM Observations
Date
2020-01-15T13:42:25Z (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 S200115j and using the latest BAYESTAR skymap, Fermi-GBM was observing
84.4% 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 S200115j (GCN Circ. 26759). 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=137.7, Dec=23.9 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: 4.6 8.3 17.
1.024 s: 1.5 2.8 6.1
8.192 s: 0.5 0.7 2.0
Assuming the median luminosity distance of 331 Mpc from the GW detection,
we estimate the following intrinsic luminosity upper limits over the 1
keV-10 MeV energy range (in units of 10^48 erg/s):
Timescale Soft Normal Hard
---------------------------------
0.128s: 9.2 15. 52.
1.024s: 3.0 5.2 19.
8.192s: 0.9 1.3 6.1