[vsnet-grb-info 24310] LIGO/Virgo S191213g: Upper limits from Fermi-GBM Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26409
SUBJECT: LIGO/Virgo S191213g: Upper limits from Fermi-GBM Observations
DATE:    19/12/13 13:56:20 GMT
FROM:    Colleen A. Wilson at NASA/MSFC/NSSTC  <colleen.wilson at nasa.gov>

C.A. Wilson-Hodge (NASA/MSFC) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group

For S191213g and using the initial bayestar.fits.gz skymap, Fermi-GBM was observing 99.9% 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 S191213g (GCN 26402). 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     norm     hard
--------------------------------------
0.128 s:   5.4      8.9      14.
1.024 s:   2.1      2.8      6.3
8.192 s:   0.63     0.96     1.6

Assuming the median luminosity distance of 194.9 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
------------------------------------
0.128 s:     3.7      5.7     15.
1.024 s:     1.5      1.8     6.7
8.192 s:     0.44     0.62    1.7