Fermi-LAT detection of enhanced gamma-ray activity from the FSRQ PKS 2052-47
ATel #13541; S. Buson (Univ. of Wuerzburg), R. Angioni (SSDC/INFN), on behalf of the Fermi Large Area Telescope Collaboration
on 4 Mar 2020; 09:49 UT
Credential Certification: Sara Buson (sara.buson@gmail.com)
Subjects: Gamma Ray, Request for Observations, Blazar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat-spectrum radio quasar PKS 2052-47, also known as 4FGL J2056.2-4714 (The Fermi-LAT collaboration 2019, arXiv:1902.10045), with coordinates R.A. = 314.068166 deg, Decl. = -47.246563 deg (J2000; Johnston et al. 1995 AJ, 110, 880), and redshift z= 1.491 (Massaro et al. 2015 Ap&SS, 357, 75).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on March 2, 2020, with a daily averaged gamma-ray flux (E>100MeV) of (1.2+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). It corresponds to a flux increase of a factor of about 10 relative to the average flux reported in the fourth Fermi-LAT catalog (4FGL). This is the highest LAT daily flux observed so far for this source. The corresponding photon index is 2.3+/-0.2, and is consistent with the 4FGL value of 2.41+/-0.01.
Visual inspection of the Fermi All-sky Variability Analysis (FAVA, Abdollahi et al. 2017 ApJ, 846, 34) results suggests that the gamma-ray emission has been enhanced for several months. Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. This source will be added to the "LAT Monitored Sources" and consequently, a preliminary estimation of the daily gamma-ray flux observed by Fermi-LAT will be publicly available (http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/ ). We encourage multifrequency observations of this source. The Fermi-LAT contact person for this source is C. C. Cheung (teddy.cheung at nrl.navy.mil)
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.
