Fermi LAT detection of a GeV gamma-ray flare from the high-redshift flat spectrum radio quasar S5 0212+73
ATel #16679; Fausto Casaburo (INFN Roma Tor Vergata & SSDC ASI), Federica Giacchino (INFN Roma Tor Vergata & SSDC ASI), Stefano Ciprini (INFN Roma Tor Vergata & SSDC ASI), on behalf of the Fermi Large Area Telescope Collaboration.
on 28 Jun 2024; 22:29 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@ssdc.asi.it)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Quasar
Referred to by ATel #: 16684
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the Flat Spectrum Radio Quasar (FSRQ) S5 0212+73, also known as 1ES 0212+735, RX J0217.5+7349, and 4FGL J0217.4+7353 in the 14-year fourth Fermi-LAT catalog (4FGL) Data Release 4 (4FGL-DR4; Ballet et al. 2024, arXiv:2307.12546), with radio coordinates R.A: 34.378388 deg, Dec.: +73.825728 deg; (J2000; Johnston et al. 1995, AJ, 110, 880). This blazar is at a redshift z=2.34623 (Koss et al. 2022, ApJS, 261, 2).
Preliminary analysis indicates that on June 26, 2024, S5 0212+73 (1ES 0212+735) was in a high state with a daily average gamma-ray flux (E>100MeV) of (1.1+/-0.2) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), corresponding to a flux increase of a factor of about 35 with respect to the average flux reported in the 4FGL-DR4. The corresponding photon spectral index is 2.4+/-0.1, harder than the 4FGL-DR4 value of 2.678+/-0.081. S5 0212+73 was also detected in a high state on June 25 and June 27, 2024, with daily flux levels respectively of (0.9+/-0.4) x 10^-6 photons cm^-2 s^-1 (photon index 2.2+/-0.2) and (1.1+/-0.2) x 10^-6 photons cm^-2 s^-1 (photon index 2.4+/-0.2). This is the first time that the Fermi LAT Collaboration has reported enhanced gamma-ray activity from this blazar.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing activity of this source we strongly encourage multi wavelength observations. The gamma-ray flux light curve for FSRQ S5 0212+73 can be found in the FSSC light curve repository (LCR). For this source the Fermi-LAT contact persons are F. Casaburo (fausto.casaburo[at]roma2.infn.it), F. Giacchino (federica.giacchino[at]roma2.infn.it) and S. Ciprini (stefano.ciprini[at]roma2.infn.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.
