GCN Circular 31558
Subject
Fermi-LAT Gamma-ray Observations of IceCube-220205B
Date
2022-02-07T17:35:34Z (3 years ago)
From
Simone Garrappa at DESY <simone.garrappa@desy.de>
S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and J.
Sinapius (DESY-Zeuthen) on behalf of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the high-energy
IC220205B neutrino event (GCN 31554) with all-sky survey data from the
Large Area Telescope (LAT), on board the Fermi Gamma-ray Space
Telescope. The IceCube event was detected on 2022-02-05 20:08:10.59 UTC
(T0) with J2000 position RA = 266.80 (+/- 0.51) deg, Decl. = -3.58
(+/-0.51) deg 90% PSF containment. One cataloged >100 MeV gamma-ray
source is located within the 90% IC211216B localization error. This is
4FGL J1747.8-0316, located 0.34 deg from the neutrino best-fit position��
(The Fourth Fermi-LAT catalog DR3; The Fermi-LAT collaboration 2022,
arXiv:2201.11184). Based on a preliminary analysis of the LAT data over
a 1-month and 1-day integration time before T0, this object is not
significantly detected at gamma rays.
We searched for the existence of intermediate (months to years)
timescale emission from a new gamma-ray transient source. Preliminary
analysis indicates no significant (>5sigma) new excess emission (0.1 -
300 GeV) within the IC220205B 90% confidence localization. Assuming a
power-law spectrum (photon index = 2.0 fixed) for a point source at the
IceCube best-fit position, the >100 MeV flux upper limit (95%
confidence) is < 3.3-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 /
2022-02-05 UTC), < 2.8e-8 (< 9e-8) ph cm^-2 s^-1 for a 1-month (1-day)
integration time before T0.
Since Fermi normally operates in an all-sky scanning mode, regular
monitoring of this source will continue. For these observations the
Fermi-LAT contact persons are S. Garrappa (simone.garrappa at desy.de)
and S. Buson (sara.buson at uni-wuerzburg.de).
The Fermi LAT is a pair conversion telescope designed to cover the
energy band from 20 MeV to greater than 300 GeV. It is the product of an
international collaboration between NASA and DOE in the U.S. and many
scientific institutions across France, Italy, Japan and Sweden.