Fermi-LAT detection of renewed gamma-ray activity from the FSRQ 4C +10.45
ATel #17206; S. Wagner (University of Wuerzburg), on behalf of the Fermi Large Area Telescope Collaboration
on 27 May 2025; 09:48 UT
Credential Certification: Sarah Wagner (sarah.wagner@physik.uni-wuerzburg.de)
Subjects: Gamma Ray, >GeV, AGN, Blazar
Referred to by ATel #: 17213
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 4C +10.45, also known as 4FGL J1608.7+1029 (Abdollahi et al. 2022, ApJS, 260, 53), with coordinates R.A. = 242.19251 deg, Decl. = +10.48549 deg (J2000; Le Bail et al. 2016, AJ, 151, 79L), and redshift z=1.233 (SDSS-DR13, Albareti et al. 2017, ApJS, 233, 25).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on May 25, 2025, with a daily averaged gamma-ray flux (E>100MeV) of (1.0 +/- 0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of 35 relative to the average flux reported in the fourth data release of the fourth Fermi-LAT catalog (4FGL-DR4, Ballet et al. 2023, arXiv:2307.12546). The corresponding photon index is 2.3 +/- 0.2, and is consistent with the 4FGL value of 2.53 +/- 0.03 within the uncertainties. We have previously reported a flare of this source in ATel #16889.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. A preliminary light curve for 4C +10.45 can be accessed via the Fermi-LAT Light-Curve Repository and via the Monitored Source List. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Adithiya Dinesh (adinesh@ucm.es).
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.
