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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).
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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