Fermi-LAT detection of renewed gamma-ray activity from the FSRQ PMN J2331-2148
ATel #13586; I. Mereu (INFN, Perugia), R. Angioni (SSDC/INFN), on behalf of the Fermi Large Area Telescope Collaboration
on 24 Mar 2020; 23:07 UT
Credential Certification: Roberto Angioni (r.angioni90@gmail.com)
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 flaring activity from a source positionally consistent with the flat-spectrum radio quasar PMN J2331-2148, also known as 4FGL J2331.0-2147 (The Fermi-LAT collaboration 2020, ApJS, 247, 1), with coordinates R.A. = 352.766792 deg, Decl. = -21.804278 deg (J2000; Condon et al. 1998, AJ, 115.5,1693), and redshift z = 0.563 (Lister et al. 2011, ApJ, 742, 27).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on March 23, 2020, with a daily averaged gamma-ray flux (E>100MeV) of (1.0 +/- 0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of about 50 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 2.16 +/- 0.16, and is significantly smaller than the 4FGL value of 2.43 +/- 0.05. A previous flaring episode from this source was reported in 2009 (see ATel #2101).
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. This source is being 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. For this source, the Fermi-LAT contact person is Francesco Longo (francesco.longo@ts.infn.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.
