Fermi-LAT detection of the first bright gamma-ray flare from the FSRQ TXS 2032+117
ATel #13752; G. Principe (INAF - Istituto di Radioastronomia), on behalf of the Fermi Large Area Telescope Collaboration
on 22 May 2020; 16:08 UT
Credential Certification: Sara Buson (sara.buson@gmail.com)
Subjects: Gamma Ray, >GeV, AGN, Blazar
Referred to by ATel #: 13796
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 TXS 2032+117, also known as 4FGL J2034.6+1154 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 308.6546 deg, Decl. = +11.9087 deg (J2000; Beasley et al. 2002, ApJS, 141, 1), and redshift z=0.607 (Sowards-Emmerd et al. 2003, ApJ, 590, 1).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on 21 May 2020, with a daily averaged gamma-ray flux (E>100MeV) of (1.7+/-0.3) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). The latter corresponds to a flux increase of a factor of 70 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 2.2+/-0.1, and is significantly smaller than the 4FGL value of 2.5+/-0.1.
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 Giacomo Principe (giacomo.principe@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.
