Fermi-LAT detection of enhanced gamma-ray activity from the FSRQ S3 1444+17
ATel #16948; Omer Faruk Coban (Institute of Space Sciences, ICE-CSIC), Denis Bernard (LLR, Ecole Polytechnique & CNRS / IN2P3), Chiara Bartolini (University of Trento and INFN Bari), on behalf of the Fermi Large Area Telescope Collaboration
on 14 Dec 2024; 20:14 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 enhanced gamma-ray activity from a source positionally consistent with the flat-spectrum radio quasar S3 1444+17, also known as 4FGL J1446.7+1719 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 221.64728 deg, Decl. = +17.35211 deg (J2000; Xu et al. 2019, ApJS, 242, 5), and redshift z=1.026 (Healey et al. 2008, ApJS, 175, 97).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on December 13, 2024, with a daily averaged gamma-ray flux (E>100MeV) of (0.5+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of approximately 60 times 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 to date. The corresponding photon index is 2.0+/-0.2, and is harder than the 4FGL value of 2.6+/-0.1.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. A preliminary light curve for S3 1444+17 can be accessed via the Fermi-LAT Light-Curve Repository at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.html?source_name=4FGL_J1446.7+1719. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Ömer Faruk Çoban (coban@ice.csic.es).
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.
