[ Previous | Next | ADS ]

Fermi-LAT detection of renewed gamma-ray activity from the radio source PKS 2247-131

ATel #11141; R. Angioni (MPIfR-Bonn), S. Buson (NASA/GSFC) on behalf of the Fermi-LAT collaboration
on 8 Jan 2018; 06:44 UT
Credential Certification: Sara Buson (sara.buson@gmail.com)

Subjects: Gamma Ray, AGN, Blazar, Transient

The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray emission from a source positionally consistent with the radio source PKS 2247-131, with coordinates RA=342.4983854 deg, Dec=-12.8546736 deg (J2000; Beasley et al. 2002, ApJS, 141, 13), and no measured redshift. This source is not in any published gamma-ray catalog, but the Fermi-LAT Collaboration already reported gamma-ray flaring activity from this object in ATels #9285 and #9620. Given the localization errors of the LAT gamma-ray source, the blazar PKS 2247-131 is the most credible counterpart.

The Fermi-LAT significantly detected this object for the first time in July 2016, and since then the source has shown several periods of increased activity, as can be seen in the public Fermi-LAT light curves (http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/). The highest flux since the October 2016 outburst was observed on December 11, 2016, with a daily averaged gamma-ray flux (E>100MeV) of (4.2+/-0.3) X 10^-6 photons cm^-2 s^-1 and a single power-law photon index of 2.29+/-0.07 (statistical uncertainty only). The source has been consistently detected in the daily LAT data since then, most recently on January 3 with a daily flux of (2.3+/-0.3) X 10^-6 photons cm^-2 s^-1 and a single power-law photon index of 2.1+/-0.1 (statistical uncertainty only).

Recently, in ATel #11043 and ATel #11127, the AGILE Collaboration announced the detection of significant gamma-ray emission from AGL J2251-1239, whose sky position is consistent with the Fermi-LAT source reported here. The gamma-ray position uncertainties and the estimated flux reported by the AGILE Collaboration suggest that AGL J2251-1239 is the same object detected by the LAT, which is associated with PKS 2247-131.

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. The Fermi-LAT contact person for this source is S. Buson (sara.buson at 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.