Fermi-LAT detection of a new gamma-ray source associated with the FSRQ TXS 1520+344
ATel #15367; G. La Mura (LIP, Portugal), on behalf of the Fermi Large Area Telescope Collaboration
on 6 May 2022; 21:15 UT
Credential Certification: Giovanni La Mura (glamura@lip.pt)
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 gamma-ray emission from a source positionally consistent with the flat-spectrum radio quasar TXS 1520+344, also known as B2 1520+34, with coordinates R.A. = 230.72866 deg, Decl. = +34.23586 deg (J2000; Petrov & Taylor 2011, AJ, 142, 89), and redshift z = 1.285 (Richards et al. 2009, ApJS, 180, 67). This source is not in any published LAT catalog and was not detected by AGILE or EGRET.
Preliminary analysis indicates that this source was significantly detected (>5 sigma) in a high gamma-ray state on May 5, 2022, with a daily averaged gamma-ray flux (E>100MeV) of (0.23+/-0.08) X 10^-6 photons cm^-2 s^-1 and a single power-law photon index of 1.8+/-0.2 (statistical uncertainties only). The observation of this hard spectrum source is further corroborated by the detection of a photon with energy E = 14 GeV, observed at 13:21:03 UT, having an estimated probability of being associated with the source of p = 0.999991. The best fit gamma-ray position was located at R.A. = 230.680 deg, Decl. = +34.288 deg, with a 68% confidence radius of 0.078 deg and an angular separation of 0.066 deg from the proposed counterpart.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Giovanni La Mura (glamura@lip.pt).
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.
