150 likes | 403 Views
The Space Density of Compton Thick AGN. Erin Bonning (Yale) On behalf of Ezequiel Treister (ESO). Meg Urry (Yale) Shanil Virani (Yale). Compton Thick AGN. Defined as obscured sources with N H >10 24 cm -2 . Very hard to find (even in X-rays).
E N D
The Space Density of Compton Thick AGN Erin Bonning (Yale) On behalf of Ezequiel Treister (ESO) Meg Urry (Yale) Shanil Virani (Yale)
Compton Thick AGN • Defined as obscured sources with NH>1024 cm-2. • Very hard to find (even in X-rays). • Observed locally and needed to explain the X-ray background. • Number density highly uncertain. • High energy (E>10 keV) observations are required to find them.
INTEGRAL Survey • 2 Msec (expected 3 Msec by summer 2008) Deepest extragalactic INTEGRAL survey • XMM-LSS field • Flux limit: ~4x10-12 ergs cm-2 s-1 (20-40 keV) • Area: ~1,000 deg2 • 10 Sources, ~2 Compton thick AGN
MCG-02-08-014 INTEGRAL Mosaic (2.2 Ms) Significance Image, 20-50 keV
Exposure Map Maximum depth: 2.2 Ms (inner contour)
INTEGRAL Flux Limit vs. Exposure Time Flim t–1/2
Space Density of CT AGN X-ray background does not constrain density of CT AGN
Treister & Urry, 2005 Gilli et al. 2007 CT AGN and the XRB XRB Intensity HEAO-1 Original HEAO-1 +10% HEAO-1 +40%
Treister & Urry, 2005 Gilli et al. 2007 Most likely solution CT AGN Space Density CT AGN and the XRB XRB Intensity HEAO-1 Original HEAO-1 +10% HEAO-1 +40%
INTEGRAL AGN logN-logS Beckmann et al. 2006
Summary • INTEGRAL (& Swift) give important constraints on Compton Thick AGN (at z=0) • X-ray “background” synthesis OK • (but XRBG spectrum somewhat uncertain) • Reflection component normalization ~ 1 • (agrees with spectra) • Deeper surveys probe evolution to z~1
INTEGRAL Mosaic (2.2 Ms) Significance Image, 20-50 keV