The geometry of the obscurer

in high-redshift X-ray AGN

AGN club / Oct 2013

Johannes Buchner

in collaboration with A. Georgakakis, K. Nandra, L. Hsu, C. Rangel, M. Brightman, A. Merloni and M. Salvato

Motivation

Accretion density peaks at $z = 0.5 - 3$
X-ray luminosity usually used as proxy for Eddington accretion rate
LF, evolution of $N_H$ , AGN-Host studies, ...
Common to do with simple models, hardness ratios
What model is justified by the data?

Sample

CDF-S 4Ms: 569 detections, 334 used (galaxy contamination)
for photo-z: Coverage by Space and Ground-based telescopes (Li-Ting Hsu, in prep)

AGN X-ray spectra

Model selection on AGN X-ray spectra

Spectral analysis

photometric redshift distribution + X-ray data + model

$\Rightarrow$ model parameter probability distributions + $\log Z$

Example - Source 179 z=0.605, 2485 counts

powerlaw

$\log Z = -64.3, N_H=20$

Example - Source 179 z=0.605, 2485 counts

wabs

$\log Z = -12.7, N_H=22.28\pm 0.04$

Example - Source 179 z=0.605, 2485 counts

torus+scattering

$\log Z = -4.7, N_H=22.45\pm 0.05$

Example - Source 179 z=0.605, 2485 counts

torus+pexmon+scattering

$\log Z = 0.0, N_H=22.44\pm 0.05$

Example - Source 179 z=0.605, 2485 counts

wabs+pexmon+scattering

$\log Z = -0.3, N_H=22.49\pm 0.05$

Example - Source 179 z=0.605, 2485 counts

torus+pexmon+scattering

Preferred geometry

red: torus - small blob (wabs)

Conclusions: AGN Model

Obscuring torus is not a sphere, not a disk, something in between
Thomson scattering of intrinsic radiation
Additional compton scattering into LOS from dense region

Have now probability distributions for CDF-S, AEGIS, COSMOS

Upcoming: relations between $N_H$ and $f_{scat}$ , $R$
Upcoming: Luminosity function