SIMBAD references

2014MNRAS.439.1403M - Mon. Not. R. Astron. Soc., 439, 1403-1458 (2014/April-1)

First X-ray-based statistical tests for clumpy-torus models: eclipse events from 230 years of monitoring of Seyfert AGN.


Abstract (from CDS):

We present an analysis of multitime-scale variability in line-of-sight X-ray-absorbing gas as a function of optical classification in a large sample of Seyfert active galactic nuclei (AGN) to derive the first X-ray statistical constraints for clumpy-torus models. We systematically search for discrete absorption events in the vast archive of Rossi X-ray Timing Explorer monitoring of dozens of nearby type I and Compton-thin type II AGN. We are sensitive to discrete absorption events due to clouds of full-covering, neutral or mildly ionized gas with columns ≳ 1022–25/cm2 transiting the line of sight. We detect 12 eclipse events in 8 objects, roughly tripling the number previously published from this archive. Peak column densities span ∼ 4-26x1022/cm2, i.e. there are no full-covering Compton-thick events in our sample. Event durations span hours to months. The column density profile for an eclipsing cloud in NGC 3783 is doubly spiked, possibly indicating a cloud that is being tidally sheared. We infer the clouds' distances from the black hole to span ∼ 0.3-140x104Rg. In seven objects, the clouds' distances are commensurate with the outer portions of broad line regions (BLR), or outside the BLR by factors up to ∼ 10 (the inner regions of infrared-emitting dusty tori). We discuss implications for cloud distributions in the context of clumpy-torus models. Eight monitored type II AGN show X-ray absorption that is consistent with being constant over time-scales from 0.6 to 8.4 yr. This can either be explained by a homogeneous medium, or by X-ray-absorbing clouds that each have NH ≪ 1022/cm2. The probability of observing a source undergoing an absorption event, independent of constant absorption due to non-clumpy material, is 0.006^+0.160_-0.003 for type Is and 0.110^+0.461_-0.071 for type IIs.

Abstract Copyright: © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2014)

Journal keyword(s): galaxies: active - galaxies: Seyfert - X-rays: galaxies

Simbad objects: 58

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