Increased X-ray activity of FSRQ OQ 334/B2 1420+32 and detection of hard spectrum by Swift-XRT

ATel #13353; Raj Prince (RRI), Rukaiya Khatoon (Tezpur Univ.), and Nayantara Gupta (RRI)
on 17 Dec 2019; 06:25 UT
Credential Certification: Aditi Agarwal (aditiagarwal.phy@gmail.com)

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The gamma-ray flaring activity for the FSRQ, OQ 334/B2 1420+32, has been reported in an Atel #12942 with daily averaged flux of (8.9+/-1.1) X 10^-7 ph cm^-2 s^-1, observed by Fermi-LAT on 13 July, 2019. The Fermi quick look light curve shows that the source is still flaring “https://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/OQ334_604800_1yr.png” in gamma-ray. Referring to the current flaring activity in gamma-ray, we conducted Swift XRT and UVOT observation on 13 December, 2019 for total exposure of ~ 2.2 ks (Swift obs id: 00010520013). The preliminary analysis result using Fermi-LAT observation from 13 November to 15 December, 2019, indicates that the source has brightened in the gamma-rays to a daily averaged flux of (2.03+/-0.11)x10^-7 ph cm^-2 s^-1 (errors are statistical only) and the corresponding power-law photon index is 2.43+/-0.08. The current flux in the gamma-ray band is ~ 4 times lower than the one observed in July 2019, and the spectrum was harder with photon index 1.83+/-0.08 (Atel #12942). We report the preliminary analysis results of Swift-XRT and UVOT observations here. Swift-XRT data were collected in Photon Counting mode for total exposure of ~ 2.2 ks. Our quick look analysis shows that the observed X-ray spectrum (0.3 – 10 keV) can be fitted by an absorbed power-law model with a fixed galactic column density in the direction of the source (n_H = 1.10 x 10^20 cm^-2; Kalberla et al. 2015, A&A, 440, 775). The preliminary unabsorbed flux in 0.3-10 keV is (8.3+/- 1.7) x 10^-12 erg cm^-2 s^-1 with a photon index of 1.35+/-0.22. The Swift-XRT analysis result using the observation of July 12, 2019 (Swift obs id: 00010520010) shows the observed flux is (5.8+/-0.8) x 10^-12 erg cm^-2 s^-2 with photon index 2.59 +/- 0.28. It is noted that the current Swift-XRT observation shows, that the flux in the X-ray band has been increased by ~ 1.5 times than the flux observed in July 2019 and the spectrum becomes much harder from 2.59 +/-0.28 to 1.35 +/-0.22. Since the Fermi-LAT publicly available light curve shows that the source is still in the high state in gamma-ray, we would like to monitor the X-ray observation over time. The simultaneous UV/optical observations were also performed in all the available six filters, viz. B, V, U, UVW1, UVM2, and UVW2, of Swift-UVOT. The preliminary observed magnitude in the AB systems for respective filters are 16.61+/-0.06, 16.15+/-0.08, 17.07+/-0.06, 17.24+/-0.05, 17.40+/-0.06, and 17.58+/-0.05. This magnitude is not corrected for Galactic extinction. The AB systems U band magnitude during the July 12, 2019 observation is 14.86+/-0.02, which is much brighter than the current U band magnitude. In consideration of the ongoing activity in gamma-ray and X-ray, we encourage further multi-wavelength observations of this object. We would like to thank the Swift team for the rapid and efficient scheduling of the ToO observation.