Fermi-LAT detection of enhanced gamma-ray activity from the FSRQ PMN J0634-2335
ATel #15300; M. Giroletti (INAF/IRA), C. C. Cheung (NRL), on behalf of the Fermi Large Area Telescope Collaboration
on 28 Mar 2022; 16:23 UT
Credential Certification: Marcello Giroletti (giroletti@ira.inaf.it)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Quasar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed enhanced gamma-ray activity from a source positionally consistent with the flat-spectrum radio quasar PMN J0634-2335, also known as 4FGL J0634.9-2335 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 98.745837 deg, Decl. = -23.586654 deg (J2000; Petrov et al. 2006, AJ, 131, 1872), and redshift z=1.535 (Ackermann et al. 2011, ApJ, 743, 171).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on 2022 March 27, with a daily averaged gamma-ray flux (E>100MeV) of (0.70+/-0.15) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of 40 relative to the average flux reported in the fourth Fermi-LAT catalog (4FGL). This is the highest daily flux ever observed for this source by the LAT. The measured photon index is 1.96+/-0.14, corresponding to a significantly harder spectrum than the 4FGL value of 2.61+/-0.07.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. A preliminary light curve can be accessed via the Fermi-LAT Light-Curve Repository at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/lcr/source.html?source_name=4FGL_J0634.9-2335. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Marcello Giroletti (marcello.giroletti@inaf.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.
