Fermi-LAT detection of renewed gamma-ray activity from the FSRQ TXS 1100+122
ATel #16997; Denis Bernard (LLR, Ecole Polytechnique & CNRS / IN2P3), on behalf of the Fermi Large Area Telescope Collaboration
on 27 Jan 2025; 16:00 UT
Credential Certification: Denis Bernard (Denis.bernard@in2p3.fr)
Subjects: Gamma Ray, >GeV, AGN, Blazar, Quasar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed renewed gamma-ray activity from a source positionally consistent with the flat-spectrum radio quasar TXS 1100+122 also known as 4FGL J1103.0+1157 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 165.76471 deg, Decl. = +11.97129 deg (J2000; Xu et al., 2019, ApJS, 242, 5), and redshift z= 0.9129 (Albareti et al., 2017, ApJS, 233, 25).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on Jan 26, 2025, with a daily averaged gamma-ray flux (E>100MeV) of (0.5 +/- 0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of 20 relative to the average flux reported in the fourth Fermi-LAT catalog (4FGL). The corresponding photon index is 2.07+/-0.22, indicating a significantly harder spectrum than the 4FGL value of 2.43+/-0.03. Previous flares from this source have been reported in ATels #6914 and #5202.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. A preliminary light curve for TXS 1100+122 can be accessed via the Fermi-LAT Light-Curve Repository at this link. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Roopesh Ojha (Roopesh.Ojha@gmail.com).
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.