Probing the circumnuclear absorbing medium of the buried AGN in NGC 1068 through NuSTAR observations

Abstract

We present the results of the latest NuSTAR monitoring campaign of the Compton-thick Seyfert 2 galaxy NGC 1068, composed of four $\sim$50 ks observations performed between July 2017 and February 2018 to search for flux and spectral variability on timescales from 1 to 6 months. We detect one unveiling and one eclipsing event with timescales less than 27 and 91 days, respectively, ascribed to Compton-thick material with $N_H=(1.8\pm 0.8)\times 10^{24}$ cm${}^{-2}$ and $N_H\ge (2.4\pm 0.5)\times 10^{24}$ cm${}^{-2}$ moving across our line of sight. This gas is likely located in the innermost part of the torus or even further inward, thus providing further evidence of the clumpy structure of the circumnuclear matter in this source. Taking advantage of simultaneous Swift-XRT observations, we also detected a new flaring ULX, at a distance $d\sim$30" (i.e. $\sim$2 kpc) from the nuclear region of NGC 1068, with a peak X-ray intrinsic luminosity of $(3.0\pm 0.4)\times 10^{40}$ erg s${}^{-1}$ in the 2-10 keV band.

14 pages, 12 figures, 7 tables. MNRAS in press

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• Compton-Thick AGN in the NuSTAR era VIII: A joint NuSTAR-XMM-Newton monitoring of the changing-look Compton-thick AGN NGC 1358
• Dynamical evidence of the sub-parsec counter-rotating disc for a close binary of supermassive black holes in the nucleus of NGC 1068
• The X-ray emission of the Seyfert 2 galaxy MCG-01-24-12
• X-ray spectral and timing analysis of the Compton Thick Seyfert 2 galaxy NGC 1068
• Multi-epoch hard X-ray view of Compton-thick AGN Circinus Galaxy
• Probing the Extent of Fe K$\alpha$ Emission in Nearby Active Galactic Nuclei using Multi-Order Analysis of Chandra High Energy Transmission Grating Data