LIGO/Virgo S190720a: Upper limits from Fermi-GBM Observations
Abstract
For the LIGO/Virgo detection of GW trigger S190720a (GCN 25115) and using the initial BAYESTAR skymap, Fermi-GBM was observing 73.2% of the localization probability at event time. There was no Fermi-GBM onboard trigger around the event time of S190720a. 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 10^-8 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 37. 57. 110. 1.024 s: 13. 17. 40. 8.192 s: 3.2 4.9 9.5 Assuming the median luminosity distance of 1071 Mpc (z=0.215) 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: 78.6 110. 352. 1.024 s: 27.6 32.7 128. 8.192 s: 6.80 9.42 30.4
- Publication:
-
GRB Coordinates Network
- Pub Date:
- July 2019
- Bibcode:
- 2019GCN.25122....1W