GCN Circular 24537
Subject
LIGO/Virgo S190513bm: Fermi GBM Observations
Date
2019-05-14T12:36:11Z (6 years ago)
From
Suraj Poolakkil at UAH <sp0076@uah.edu>
S. Poolakkil (UAH) and A. Goldstein (USRA) report on behalf of the
Fermi-GBM Team and the GBM-LIGO/Virgo group:
For S190513bm, and using the updated BAYESTAR skymap, Fermi-GBM was
observing 61.6% 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 S190513bm (GCN 24522). 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 = 280.7 and Dec = -12.3 with a radius of 67.4 degrees.
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 the remaining visible GW localization probability
(in units of erg/s/cm^2):
Timescale soft norm hard
--------------------------------------
0.128 s: 3.5e-07 5.5e-07 1.0e-06
1.024 s: 1.2e-07 2.0e-07 3.5e-07
8.192 s: 3.5e-08 5.9e-08 1.2e-07
Assuming the median luminosity distance of ~1987 Mpc from the GW detection,
we estimate intrinsic luminosity upper limits of (2.6-26.2)E49 erg/s for the
soft template, (3.9-36.5)E49 erg/s for the normal template, and
(1.3-11.2)E50
erg/s for the hard template over the 1 keV-10 MeV energy range.