Fermi-LAT detection of a new gamma-ray source associated with the flat-spectrum radio source PMN J1606-0353
ATel #13389; R. Angioni (SSDC/INFN) and C. C. Cheung (NRL) on behalf of the Fermi Large Area Telescope Collaboration
on 7 Jan 2020; 14:10 UT
Credential Certification: Roberto Angioni (r.angioni90@gmail.com)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN
Referred to by ATel #: 13708
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray emission from a source positionally consistent with the flat-spectrum radio source PMN J1606-0353, also known as CRATES J1606-0353, with coordinates R.A. = 241.686750 deg, Decl. = -3.894528 deg (J2000; Condon et al. 1998 AJ,115,1693), and unknown redshift. This source is not in any published LAT catalog and was not detected by AGILE or EGRET.
Preliminary analysis indicates that this source was significantly detected (>5 sigma) in a high gamma-ray state on 31 December 2019, with a daily averaged gamma-ray flux (E>100MeV) of (4.9+/-1.8) X 10^-7 photons cm^-2 s^-1 and a single power-law photon index of 2.0+/-0.2 (statistical uncertainties only). The highest energy photon associated with this transient (with probability >99%) was also recorded on this day at 22:44:14.235 UTC, with an energy of ~27 GeV. The latest significant detection of this transient in Fermi-LAT daily data was on 5 January 2020, with a daily averaged gamma-ray flux (E>100MeV) of (3.2+/-1.4) X 10^-7 photons cm^-2 s^-1 and a single power-law photon index of 1.9+/-0.2 (statistical uncertainties only), while on 6 January 2020 the source was not detected, with a flux upper limit of (E>100MeV) of 1.3 X 10^-7 photons cm^-2 s^-1.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage multifrequency observations of this source. Optical spectroscopy would be especially useful since the object does not have a measured redshift. For this source, the Fermi-LAT contact person is Roberto Angioni (roberto.angioni@ssdc.asi.it).
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.
