Fermi LAT detection of renewed GeV gamma-ray flaring activity from OQ 334 (B2 1420+32)

ATel #13382; S. Ciprini (1. INFN Tor Vergata, Rome; 2. ASI Space Science Data Center, Rome), C. C. Cheung (U. S. Naval Research Laboratory, Washington), on behalf of the Fermi Large Area Telescope Collaboration
on 1 Jan 2020; 20:15 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@ssdc.asi.it)

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The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray emission from a source positionally consistent with the flat spectrum radio quasar OQ 334 (also known as B2 1420+32, GB2 1420+326 and 4FGL J1422.3+3223, The Fermi-LAT Collaboration 2019, arXiv:1902.10045), with radio coordinates (J2000) R.A.: 215.626579deg, Dec.: 32.386233deg (Petrov & Taylor 2011, AJ, 142, 89). This blazar has a redshift z=0.6819 (Hewett & Wild 2010, MNRAS, 405, 2302).

OQ 334 (B2 1420+32) was in a renewed high-brightness state in GeV gamma rays during December 2019, and its activity increased substantially starting on December 28, 2019. In particular, preliminary analysis indicates that on 2018 December 30 and 31, OQ 334 was in a high state with a daily averaged gamma-ray flux (E>100 MeV) of (0.9+/-0.1) X 10^-6 photons cm^-2 s^-1 and (1.7+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only) respectively, about 110 and 210 times greater than its eight-year average flux reported in the fourth Fermi-LAT source catalog (4FGL). The corresponding single power-law photon spectral indexes (E>100 MeV) are 1.9+/-0.1 and 2.1+/-0.1 respectively (statistical uncertainty only).

The peak 6-hour integrated gamma-ray flux (E>100 MeV) of (2.0+/-0.3) X 10^-6 photons cm^-2 s^-1 was reached by OQ 334 on 2019 December 31 in two intervals (06:00-12:00 UT and 18:00-23:59 UT).

This is the third announcement by the Fermi LAT Collaboration of an increasing gamma-ray flux trend for this blazar, after ATel#12277 and ATel#12942. The source is in the "LAT Monitored Sources" table at FSSC, and consequently preliminary estimations of the daily and weekly gamma-ray fluxes observed by Fermi LAT are publicly available. OQ 334 was announced to be in high flux states also in the optical band and X-rays in several occasions during the second half of 2019 (for example ATel#12379, ATel#12866, ATel#12886, ATel#12887, ATel#12914, ATel#12941, ATel#13028, ATel#13353).

Because Fermi 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. For this source the Fermi LAT contact persons are S. Ciprini (stefano.ciprini@ssdc.asi.it) and C. C Cheung (Teddy.Cheung@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.