Fermi-LAT detection of enhanced gamma-ray activity from FSRQ 4C +31.03
ATel #16068; Sara Cutini (INFN-Perugia) on behalf of the Fermi-LAT Collaboration
on 1 Jun 2023; 09:47 UT
Credential Certification: Isabella Mereu (mereuisabella@gmail.com)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Quasar, Transient
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray fast flaring activity from a source positionally consistent with the flat spectrum radio quasar 4C +31.03, also known as 4FGL J0112.8+3208 and 3FHL J0112.9+3208 (Abdollahi, et al. 2020, ApJS, 247, 33; Ajello et al. 2017, ApJS, 232, 18), with radio coordinates R.A. = 18.20972 deg, Dec. = 32.13818 deg (J2000; Beasley et al. 2002, ApJS, 141, 13), and redshift z=0.603 (Wills & Wills 1976, ApJS, 31, 143).
Preliminary analysis indicates that 4C +31.03 was in a flaring state on May 31, 2023, reaching its historical maximum with a daily averaged gamma-ray flux (E>100MeV) of (4.9+/-0.3) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of about 70 with respect to the average flux reported in the fourth Fermi-LAT catalog (4FGL). The corresponding power-law photon index is about 1.9+/- 0.1, where the 4FGL value is 2.37+/-0.02. At least one photon of 44 GeV energy is also spatially consistent with this blazar. This is the third time that the Fermi-LAT Collaboration has reported enhanced gamma-ray activity from 4C +31.03, with prior reports in May 2009 (ATel#2054) and January 2023 (ATel#15841).
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of 4C +31.03 will continue. A preliminary uncalibrated estimation of the daily gamma-ray flux observed by Fermi LAT is publicly available at https://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/4C31.03_86400.png, and this blazar source has also an entry in the FSSC light curve repository (Abdollahi S. et al. 2023, ApJS, 265, 31, https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.html?source_name=4FGL_J0112.8+3208). We encourage multifrequency observations of this gamma-ray source. For this source, the Fermi-LAT contact persons are E. Cavazzuti (elisabetta.cavazzuti@asi.it) and S. Ciprini (stefano.ciprini@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.
