Fermi-LAT detection of renewed gamma-ray activity from the FSRQ PKS 0736+01
ATel #16179; Denis Bernard (LLR, Ecole Polytechnique & CNRS / IN2P3), on behalf of the Fermi Large Area Telescope Collaboration
on 10 Aug 2023; 07:35 UT
Credential Certification: Denis Bernard (Denis.bernard@in2p3.fr)
Subjects: Gamma Ray, >GeV, Request for Observations, 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 PKS 0736+01, also known as 4FGL J0739.2+0137 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 114.825141 deg, Dec = 1.617950 deg (J2000, Johnston et al. 1995, AJ, 110, 880), and redshift 0.18941 (Ho & Kim, 2009, ApJS, 184, 398).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on Aug 8, 2023, with a daily averaged gamma-ray flux (E>100MeV) of (1.7 +/- 0.4) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of 15 relative to the average flux reported in the fourth Fermi-LAT catalog (4FGL). The corresponding photon index is 2.01 +/- 0.15, and is significantly smaller than the 4FGL value of 2.41 +/- 0.014. The previous report for enhanced gamma-ray activity from PKS 0736+01 by the Fermi LAT Collaboration was in November 2014 (ATel#6731).
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_J0739.2+0137. A preliminary estimation of the daily gamma-ray flux observed by Fermi-LAT is also publicly available on the LAT Monitored Source page at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/PKS_0736p01. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Filippo D'Ammando (filippo.dammando@fisica.unipg.it).
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.
