Fermi-LAT detection of enhanced gamma-ray activity from the FSRQ PKS 2245-328
ATel #16035; Denis Bernard (LLR, Ecole Polytechnique & CNRS / IN2P3), on behalf of the Fermi Large Area Telescope Collaboration
on 12 May 2023; 18:28 UT
Credential Certification: Denis Bernard (Denis.bernard@in2p3.fr)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed enhanced gamma-ray activity from a source positionally consistent with the flat-spectrum radio quasar PKS 2245-328, also known as 4FGL J2248.7-3235 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 342.161190 deg, Decl. = -32.597830 deg (J2000; Johnston K. J. et al. 1995, AJ 110, 880), and redshift z=2.268 (Peterson B. A. et al., 1979, ApJ 232, 400).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on May 11, 2023 , with a daily averaged gamma-ray flux (E>100MeV) of (0.56 +/- 0.19) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of about 40 relative to the average flux reported in the fourth Fermi-LAT catalog (4FGL). This is the highest LAT daily flux ever observed for this source. The corresponding photon index is 2.3 +/- 0.3, and corresponds to a significantly harder spectrum than the 4FGL value of 2.76 +/- 0.07.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Denis Bernard (denis.bernard@in2p3.fr).
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.
