Astronomy and Astrophysics – Astrophysics – High Energy Astrophysical Phenomena
Scientific paper
2009-10-15
Astronomy and Astrophysics
Astrophysics
High Energy Astrophysical Phenomena
Accepted to ApJ, 34 pages, 8 figures, 1 table
Scientific paper
We present the 2D ionization structure of self-similar MHD winds off accretion disks around irradiated by a central X-ray source. Based on earlier observational clues and theoretical arguments, we focus our attention on a subset of these winds, namely those with radial density dependence n(r)~1/r. We employ the photoionization code XSTAR to compute the ionic abundances of a large number of ions of different elements and then compile their line-of-sight (LOS) absorption columns. Particular attention is paid to the absorption measure distribution (AMD), namely their Hydrogen-equivalent column per logarithmic ionization parameter \xi interval, d N_H/(d \log \xi), which provides a measure of the winds' radial density profiles. For n(r)~1/r the AMD is found to be independent of \xi, in good agreement with its behavior inferred from the X-ray spectra of several AGNs. For the specific wind structure and X-ray spectrum we also compute detailed absorption line profiles for a number of ions to obtain their LOS velocities, v~100-300 km/sec (at \log \xi~2-3) for Fe XVII and v~1,000-4,000 km/sec (at \log \xi~4-5) for Fe XXV, in good agreement with the observation. Our models describe the X-ray absorption properties of these winds with only two parameters, namely the mass-accretion rate \dot{m} and LOS angle \theta. The probability of obscuration of the X-ray ionizing source in these winds decreases with increasing \dot{m} and increases steeply with \theta. As such, we concur with previous authors that these wind configurations, viewed globally, incorporate all the requisite properties of the parsec scale "torii" invoked in AGN unification schemes. We indicate that a combination of the AMD and absorption line profile observations can uniquely determine these model parameters and their bearing on AGN population demographics.
Behar Ehud
Contopoulos Ioannis
Fukumura Keigo
Kazanas Demosthenes
No associations
LandOfFree
MHD Accretion-Disk Winds as X-ray Absorbers in AGNs does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with MHD Accretion-Disk Winds as X-ray Absorbers in AGNs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and MHD Accretion-Disk Winds as X-ray Absorbers in AGNs will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-123102