Fermi LAT detection of renewed GeV gamma-ray activity from the flat spectrum radio quasar OQ 334
ATel #16680; 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 30 Jun 2024; 14:12 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@ssdc.asi.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 gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar (FSRQ) OQ 334, also known as B2 1420+32, GB2 1420+326 and 4FGL J1422.3+3223 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: 215.626579 deg, Dec.: 32.386233 deg; (J2000; Petrov & Taylor 2011, AJ, 142, 89). This blazar has a redshift z=0.6819 (Hewett & Wild 2010, MNRAS, 405, 2302).
Preliminary analysis indicates that on June 27, 2024, OQ 334 (B2 1420+32) was in a high state with a daily average gamma-ray flux (E>100MeV) of (4.4+/-0.3) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), corresponding to a flux increase of a factor of about 60 higher than the average flux reported in the 4FGL-DR4. The corresponding single power law photon spectral index (E>100 MeV) is 2.18+/-0.14, which is comparable to the 4FGL-DR4 value of 2.239+/-0.011.
The averaged daily gamma-ray flux measured on June 27, 2024 is approximately 2.5 times higher than the flux reported on January 1, 2020 in ATel#13382. The peak 6-hour integrated gamma-ray flux (E>100 MeV) of (6.5+/-0.7) X 10^-6 photons cm^-2 s^-1 was reached by OQ 334 on June 27, 2024 in the 6-hour interval (06:00-12:00 UT).
On June 26, 2024 the daily flux level was (0.9+/-0.1) x 10^-6 photons cm^-2 s^-1 (photon index 2.2+/-0.2), and on June 28 the daily flux level is (1.8+/-0.2) x 10^-6 photons cm^-2 s^-1 (photon index 2.2+/-0.1). This is the fourth time that the Fermi LAT Collaboration has reported enhanced gamma-ray activity from this blazar, after ATel#13382, ATel#12942, ATel#12277.
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 encourage multiwavelength observations. The gamma-ray flux light curve for OQ 334 can be found in the FSSC light curve repository (LCR). For this source the Fermi-LAT contact persons are Stefano Ciprini (stefano.ciprini[at]roma2.infn.it) and C. C. Cheung (teddy.cheung[at]nrl.navy.mil).
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.