Search

Relativistic Fe K emission lines from accretion discs and from disc winds encode key information about black holes, and their accretion and feedback mechanisms. We show that these two processes can in principle produce indistinguishable line profiles, such that they cannot be disentangled spectrally. We argue that it is likely that in many cases both processes contribute to the net line profile, and their relative contributions cannot be constrained purely by Fe K spectroscopy. In almost all studies of Fe K emission to date, a single process (either disc reflection or wind Compton scattering) is assumed to dominate the total line profile. We demonstrate that fitting a single process emission model (pure reflection or pure wind) to a hybrid line profile results in large systematic biases in the estimates of key parameters, such as mass outflow rate and spin. We discuss various strategies to mitigate this effect, such as including high-energy data covering the Compton hump, and the implications for future X-ray missions. [ABSTRACT FROM AUTHOR]

We report on deep XMM–Newton and NuSTAR observations of the high redshift, z  = 2.94, extremely red quasar (ERQ), SDSS J165202.60+172852.4, with known galactic ionized outflows detected via spatially resolved [O  iii ] emission lines. X-ray observations allow us to directly probe the accretion disc luminosity and the geometry and scale of the circumnuclear obscuration. We fit the spectra from the XMM–Newton /EPIC and NuSTAR detectors with a physically motivated torus model and constrain the source to exhibit a near Compton-thick column density of N H = (1.02 |$^{+0.76}_{-0.41}$|⁠) × 1024 cm−2, a near edge-on geometry with the line-of-sight inclination angle of θi  = 85°, and a scattering fraction of f sc ∼ 3  per cent. The absorption-corrected, intrinsic 2–10 keV X-ray luminosity of L 2–10= (1.4 |$^{+1}_{-1}$|⁠) × 1045 erg s−1 reveals a powerful quasar that is not intrinsically X-ray weak, consistent with observed trends in other ERQs. We also estimate the physical properties of the obscuration, although highly uncertain: the warm ionized scattering density of n e ∼ 7.5 × (102–103) cm−3 and the obscuration mass of |$M_{\rm obsc} \sim 1.7\times (10^4\!-\!10^6)\,{\rm M}_{\odot}$|⁠. As previously suggested with shallower X-ray observations, optical and infrared selection of ERQ has proved effective in finding obscured quasars with powerful outflow signatures. Our observations provide an in-depth view into the X-ray properties of ERQs and support the conclusions of severely photon-limited studies of obscured quasar populations at high redshifts. [ABSTRACT FROM AUTHOR]

We present the results obtained from a detailed X-ray timing and spectral analysis of the Seyfert 2 galaxy NGC 6300 by using observations from the Suzaku observatory, the Chandra X-ray Observatory and the Nuclear Spectroscopic Telescope Array (NuSTAR) mission between 2007 and 2016. We calculate the variance and the rms fractional variability of the source in different energy bands and we find variabilities in various energy bands. Spectral properties of the source are studied by using various phenomenological and physical models. The properties of the Compton clouds, reflection, Fe Kα line emission and soft X-ray excess are studied in detail. Several physical parameters of the source are extracted and investigated to establish the presence/absence of any correlation between them. We also investigate the nature of the circumnuclear 'torus' and we find that the torus is not uniform, but clumpy. The observed changes in the line-of-sight column density can be explained in terms of transiting clouds. The iron line-emitting region is found to be different in the different epochs of observations. We also observe that the torus and the nucleus independently evolve over the years. [ABSTRACT FROM AUTHOR]

We present the results of the latest NuSTAR monitoring campaign of the Compton-thick Seyfert 2 galaxy NGC 1068, composed of four ∼50 ks observations performed between 2017 July and 2018 February to search for flux and spectral variability on time-scales from 1 to 6 months. We detect one unveiling and one eclipsing event with time-scales less than 27 and 91 d, respectively, ascribed to Compton-thick material with N H = (1.8 ± 0.8) × 1024 and ≥ (2.4 ± 0.5) × 1024 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  ∼ 30 arcsec (i.e. ∼2 kpc) from the nuclear region of NGC 1068, with a peak X-ray intrinsic luminosity of (3.0 ± 0.4) × 1040 erg s−1 in the 2–10 keV band. [ABSTRACT FROM AUTHOR]