Fast ionized X-ray absorbers in AGNs

Autor: Demos Kazanas, Ioannis Contopoulos, K. Fukumura, Ehud Behar, Francesco Tombesi, Chris Shrader
Rok vydání: 2016
Předmět:
Zdroj: Astronomische Nachrichten. 337:454-458
ISSN: 0004-6337
DOI: 10.1002/asna.201612329
Popis: We investigate the physics of the X-ray ionized absorbers often identified as warm absorbers (WAs) and ultra-fast outflows (UFOs) in Seyfert AGNs from spectroscopic studies in the context of magnetically-driven accretion-disk wind scenario. Launched and accelerated by the action of a global magnetic field anchored to an underlying accretion disk around a black hole, outflowing plasma is irradiated and ionized by an AGN radiation field characterized by its spectral energy density (SED). By numerically solving the Grad-Shafranov equation in the magnetohydrodynamic (MHD) framework, the physical property of the magnetized disk-wind is determined by a wind parameter set, which is then incorporated into radiative transfer calculations with xstar photoionization code under heating-cooling equilibrium state to compute the absorber's properties such as column density NH, line-of-sight (LoS) velocity v, ionization parameter ς, among others. Assuming that the wind density scales as n ∝ r–1, we calculate theoretical absorption measure distribution (AMD) for various ions seen in AGNs as well as line spectra especially for the Fe Kα absorption feature by focusing on a bright quasar PG 1211+143 as a case study and show the model's plausibility. In this note we demonstrate that the proposed MHD-driven disk-wind scenario is not only consistent with the observed X-ray data, but also help better constrain the underlying nature of the AGN environment in a close proximity to a central engine. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Databáze: OpenAIRE
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