GCN Circular 25523
Subject
LIGO/Virgo S190828l: Upper limits from Fermi-GBM Observations
Date
2019-08-28T16:15:56Z (5 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres (UAH) reports on behalf of the Fermi-GBM Team and the
GBM-LIGO/Virgo group:
For S190828l and using the initial bayestar skymap, Fermi-GBM was observing
29% 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 S190828l (GCN 25503). 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 (in units of erg/s/cm^2):
Timescale Soft Normal Hard
------------------------------------
0.128 s: 1.8e-07 2.3e-07 5.0e-07
1.024 s: 6.4e-08 1.0e-07 2.1e-07
8.192 s: 2.7e-08 3.5e-08 7.7e-08
Assuming the median luminosity distance of 1609 Mpc (z=0.31) 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: 8.9 10 37
1.024 s: 3.2 4.4 16
8.192 s: 1.3 1.5 5.7