Fermi-LAT detection of enhanced gamma-ray activity from the FSRQ PKS 0405-385
ATel #16183; Denis Bernard (LLR, Ecole Polytechnique & CNRS / IN2P3), on behalf of the Fermi Large Area Telescope Collaboration
on 11 Aug 2023; 18:01 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 enhanced gamma-ray activity from a source positionally consistent with the flat-spectrum radio quasar PKS 0405-385, also known as 4FGL J0407.0-3826 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 61.745980 deg, Decl. = -38.441123 deg (J2000; Fey, 2004, AJ, 127, 3587), and redshift z=1.285 (Gattano, 2018, A&A, 618, 80).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on August 9, 2023, with a daily averaged gamma-ray flux (E>100MeV) of (0.8 +/- 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 2.2 +/- 0.2, and is consistent with the 4FGL value of 2.36 +/- 0.02 within the uncertainties.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. This source has an entry in the FSSC light curve repository (https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.html?source_name=4FGL_J0407.0-3826). 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.