[vsnet-grb-info 22863] LIGO/Virgo S190701ah: Upper limits from Fermi-GBM Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24962
SUBJECT: LIGO/Virgo S190701ah: Upper limits from Fermi-GBM Observations
DATE:    19/07/02 04:12:56 GMT
FROM:    Peter Veres at UAH  <veresp at gmail.com>

P. Veres (UAH), R. Hamburg (UAH) and C. Fletcher (USRA) report on behalf of
the
Fermi-GBM Team and the GBM-LIGO/Virgo group:

For S190701ah, and using the bayestar.fits skymap, Fermi-GBM was
observing 100% 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 S190701ah (GCN 24950). 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 spectral 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 erg/s/cm^2):


Timescale  soft     norm     hard
--------------------------------------
0.128 s:   5.1e-07  8.5e-07  1.2e-06
1.024 s:   1.5e-07  2.6e-07  3.9e-07
8.192 s:   3.5e-08  7.7e-08  1.5e-07


Assuming the median luminosity distance of 1045 Mpc (z=0.21) from the GW
detection, we estimate intrinsic luminosity upper limits of (0.71-10)E49
erg/s for the
soft template, (1.4-16)E49 erg/s for the normal template, and
(4.6-36)E49 erg/s for the hard template over the 1 keV-10 MeV energy range.