Fermi-LAT Gamma-ray Observations of IceCube-220205A and detection of Fermi J1420.7+1653
ATel #15211; S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg), C. C. Cheung (Naval Research Laboratory) and J. Sinapius (DESY-Zeuthen) on behalf of the Fermi-LAT collaboration
on 7 Feb 2022; 17:27 UT
Credential Certification: Simone Garrappa (simone.garrappa@gmail.com)
Subjects: Gamma Ray, Neutrinos, Request for Observations, AGN, Blazar
We report an analysis of observations of the vicinity of the high-energy IC220205A neutrino event (GCN 31551) 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 00:22:39.74 UTC (T0) with J2000 position RA = 216.12 (+2.94, -3.52) deg, Dec = 15.56 (+3.26, -2.65) deg 90% PSF containment. Several cataloged >100 MeV gamma-ray sources are located within the 90% IC220205A localization error (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-day integration time before T0, none of them is significantly detected at gamma rays.
Within the 90% confidence localization of the neutrino, ~1.6 deg offset from the best-fit IC220205A position, an excess of gamma rays, Fermi J1420.7+1653 was detected in an analysis of the integrated LAT data (> 100 MeV) between 2008-08-04 and 2022-02-05. This putative new source is detected at a statistical significance of ~5 sigma (calculated following the prescription adopted in the 4FGL catalog: Abdollahi, et al. 2020, ApJS, 247, 33). Assuming a power-law spectrum, the candidate gamma-ray source has best-fit localization (J2000) RA = 215.197 deg, Dec = 16.889 deg (0.16 deg 99% containment radius, 0.08 deg 68% containment radius), with best-fit spectral parameters flux = (3 +/- 1)e-9 ph cm^-2 s^-1 and index = 2.4 +/- 0.2. All values include the statistical uncertainty only. In a preliminary analysis of the LAT data over one day and one month prior T0, Fermi J1420.7+1653 is not significantly detected in the LAT data.
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). We encourage multifrequency observations of this source.
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.
This is an addendum to ATel #15210 due to characters limit.
