Fermi-LAT Detection of Flaring Gamma-ray Emission from the AGN TXS 1923+123
ATel #8492; Bryce Carpenter (CUA/NASA/GSFC) and Roopesh Ojha (NASA/GSFC/UMBC) on behalf of the Fermi Large Area Telescope Collaboration
on 1 Jan 2016; 16:32 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)
Subjects: Gamma Ray, >GeV, AGN, Blazar, Quasar
The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space
Telescope has observed a hard-spectrum gamma-ray flare from a source
positionally consistent with the AGN TXS 1923+123 with radio coordinates RA:
19h25m40.8170s, Dec: 12d27m38.087s, J2000, (Petrov et al. 2005, AJ,
129, 1163). There is no redshift for this source reported in the
literature.
Preliminary analysis indicates that on 30 December 2015 this source
was in a high-flux state, with a daily averaged gamma-ray flux
(E>100MeV) of (1.0+/-0.3) X 10^-6 photons cm^-2 s^-1 (statistical
uncertainty only) corresponding to a flux increase of a factor of
about 20 over its four-year average flux (3FGL J1925.7+1228; Acero et
al. 2015, ApJS, 218, 23). The corresponding photon spectral index of
2.0+/-0.2 is significantly harder than the 3FGL value 2.6+/-0.1.
Because Fermi 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 further multifrequency observations of this source. The
Fermi LAT contact person is Bryce Carpenter (carpbr01@gmail.com).
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.
