[ Previous | Next | ADS ]

Fermi-LAT detection of increased gamma-ray activity from the radio source PMN J0852-5755

ATel #11064; R. Angioni (MPIfR-Bonn), S. Buson (NASA/GSFC) on behalf of the Fermi-LAT collaboration
on 15 Dec 2017; 23:02 UT
Credential Certification: Sara Buson (sara.buson@gmail.com)

Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Transient

The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed enhanced gamma-ray emission from a source positionally consistent with the radio source PMN J0852-5755, also known as 3FGL J0852.6-5756 (Acero et al. 2015, ApJS, 218, 23), with coordinates R.A. = 133.161250 deg, Decl. = -57.925056 deg (J2000; Murphy et al. 2010 MNRAS, 402, 2403), and no measured redshift.

Preliminary analysis indicates that this source went into a high-flux state starting from 11 December 2017, which continued over the following days, 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) on 14 December. The latter corresponds to a flux increase of a factor of about 30 relative to the average flux reported in the third Fermi-LAT catalog (3FGL), and it is the highest gamma-ray daily flux ever recorded for this source. The corresponding photon index of 1.95+/-0.15 is significantly harder than the 3FGL value of 2.40+/-0.06, a behavior typically observed in flaring Flat-Spectrum Radio Quasars (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. The Fermi-LAT contact person for this source is R. Angioni (angioni at 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.