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Fermi-LAT detection of strong gamma-ray activity from the FSRQ PKS 0346-27

ATel #11251; R. Angioni (MPIfR-Bonn) on behalf of the Fermi-LAT Collaboration
on 3 Feb 2018; 17:39 UT
Credential Certification: Sara Buson (sara.buson@gmail.com)

Subjects: Gamma Ray, Request for Observations, AGN, Blazar

Referred to by ATel #: 11269

The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed strong gamma-ray flaring activity from a source positionally consistent with the flat-spectrum radio quasar PKS 0346-27, also known as 3FGL J0348.6-2748 (Acero et al. 2015, ApJS, 218, 23), with coordinates R.A. = 57.1589354 deg, Decl. = -27.8204344 deg (J2000; Beasley et al. 2002 ApJS, 141, 13), and a redshift of 0.991 (White et al. 1988 ApJ, 327, 561).

Preliminary analysis indicates that this source went into a high-flux state starting on 2 February 2018, reaching a peak daily averaged gamma-ray flux (E>100MeV) of (1.0+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only) . The latter corresponds to a flux increase of a factor of about 115 relative to the average flux reported in the third Fermi-LAT catalog (3FGL). This is the highest LAT daily flux ever observed for this source. The corresponding photon spectral index of 2.0+/-0.1 is significantly harder than the 3FGL value of 2.4+/-0.1. Therefore PKS 0346-27 is another example of the "harder-when-brighter" behavior observed in flaring FSRQs.

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. For this source the Fermi-LAT contact person is R. Angioni (angioni@mpifr-bonn.mpg.de).

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.