Fermi-LAT detection of renewed gamma-ray activity from the FSRQ PKS 1454-354
ATel #14700; S. Garrappa (DESY Zeuthen) on behalf of the Fermi Large Area Telescope Collaboration
on 11 Jun 2021; 22:44 UT
Credential Certification: Simone Garrappa (simone.garrappa@gmail.com)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar
Referred to by ATel #: 14712
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed renewed gamma-ray flaring activity from a source positionally consistent with the flat-spectrum radio quasar PKS 1454-354, also known as 4FGL J1457.4-3539 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 224.361299 deg, Decl. = -35.652770 deg (J2000; Fey et al. 2006, AJ, 132, 1944), and redshift z=1.424 (Jackson et al. 2002, A&A, 386, 97).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on 10 June 2021, with a daily averaged gamma-ray flux (E>100MeV) of (3.6+/-0.7) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of 75 relative to the average flux reported in the fourth Fermi-LAT catalog (4FGL-DR2; Ballet et al. 2020, arXiv:2005.11208). The corresponding photon index is 2.04+/-0.14, and is significantly smaller compared to the average value recorded in the 4FGL-DR2 catalog, i.e., 2.32+/-0.02. The current flux is comparable with the one recorded by the LAT during a previous flaring episode in September 2008 (ATel #1701). This source is one of the "LAT Monitored Sources" and consequently a preliminary estimation of the daily gamma-ray flux observed by Fermi LAT is publicly available (https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/PKS_1454-354).
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. A Swift ToO proposal has been submitted. We encourage further multifrequency observations of this source. For this source, the Fermi-LAT contact person is M. Marelli (martino.marelli at inaf.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.
