COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

Obscured AGN in the Obscured AGN in the COSMOS fieldCOSMOS field

Andrea Comastri (INAF – Bologna) on Andrea Comastri (INAF – Bologna) on behalf of the XMM-COSMOS teambehalf of the XMM-COSMOS team

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

High redshift obscured quasarsHigh redshift obscured quasars

- Unbiased tracers of SMBH/Host Galaxy “Co-evolution”

- Obscured (hard) X—ray emission SMBH is present and the host galaxy is visible morphology of obscured AGN

- ACF - Interactions

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

Looking for obscured quasars: Looking for obscured quasars: a combined a combined XrayXray, , opticaloptical, , near infrarednear infrared selection selection

Selection of high-z obscured QSO:from X-ray + photo-z catalog

•optical-to-near-infrared color (R-K>4)

•X-ray-to-optical color (X/O>10)

•photometric redshift (zphot>1)

(adapted from Brusa et al. 2005)

Shallow X-ray flux + large area pick-up the most extreme sources

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

Luminosity vs. column densityLuminosity vs. column density

Spectral analysis of thebrightest X-ray sources

~50% are indeed QSO2!

adapted from Brusa et al. 2005

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

X-ray emitting EROs at z~1.4 Average X-ray spectrum

NH= 3. 10^22

L(X)= 10^44

The K-brightest objects will be observed withthe low resolution IR(JHK) AMICI spectrograph at TNG

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

Morphological test on primary/secondary identificationsMorphological test on primary/secondary identifications

Most of the counterparts (~80%) of hard sources (undetected in the soft band)are extended (obscured nucleus both in X-ray and optical bands) and “reddish” ( ~60% with R-K>4; to be compared with 25% for the total number of primary IDs) with 0.8 <zphot< 1.8 ( ~ 70%)

Excellent consistency between X-ray spectra and optical (ACS + color) data

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

Angular Correlation Function in COSMOSAngular Correlation Function in COSMOS

The large connected area should allow the determination of the angular correlation function

w(θ) = (θ/θ0)-γ

up to a large scale

Complementary to Chandra data from which w(θ) is well measured for 5 < θ < 100 arcsec: γ ~ 1; θ0 ~ 10 arcsec

Giacconi et al. 2001CDFS – 120 ksec

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

Chandra (Yang et al. 2003) stronger signal in the hard bandΘ (h) ~ 40+-11Θ (s) ~ 4+-2 115 hard sources 298 soft sources

XMM 2dF Shallow Survey (1+1 deg2) Basilakos et al. 2004/2005 Θ (h) ~ 22+-10Θ (s) ~ 10+-2 171 hard sources432 soft sources

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

Angular Correlation Function in COSMOS:Angular Correlation Function in COSMOS:The Soft SampleThe Soft Sample

Preliminary results on 12 XMM pointings : area ~ 1.3 sq. deg.

Applying the Landy-Szalay and the Hamilton estimators (see Kerscher et al. 2000 for a comparison of the most widely used estimators) we find that :

Soft sample (0.5 – 2.0 keV):

About 650 sources –Signal for 20 < θ < 1250 arcsec(0.15 < d < 10 Mpc at z ~ 1)

γ ~ 0.45Θ0 ~ 1.5 – 2.0 arcsec ( but based on significant extrapolation …)

Cut due tointegralconstraint

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

Angular Correlation Function in COSMOS:Angular Correlation Function in COSMOS:The Hard SampleThe Hard Sample

About 310 sources Signal for 40 < θ < 1250 arcsec(0.3 < d < 10 Mpc at z ~ 1)

γ ~ 0.55Θ0 ~ 4 - 5 arcsec

Hard

Soft

Comparison betweenHard and soft ACFs

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

Angular Correlation Function in COSMOS:Angular Correlation Function in COSMOS:Preliminary conclusionsPreliminary conclusions

Both soft and hard selected samples show significant correlation from 25 – 40 arcsec up to about 20 arcmin (limit due to the integral constraint)

The slopes are somewhat flatter (γ ~ 0.5) than “canonical” values

Θ0 values ( ~ 1.5 arcsec (Soft) and ~ 4.5 arcsec (hard) ) are uncertain,but appear to be smaller than in CDFS

The hard correlation function is somewhat higher than the soft one, but not yet statistically significant (due to different redshift distribution?)

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

X-ray enhancement due to interactions?X-ray enhancement due to interactions?

Are these objects in interaction? How many do we have in the X-ray sample?

Examples of ACS images around X-ray sources : 2” radius

COSMOS Kyoto meeting May 2005COSMOS Kyoto meeting May 2005

X-ray enhancement due to interactions?X-ray enhancement due to interactions?

Preliminary analysis (Vignali et al., in progress) on a sub-sample of XMM sources with an optical identification (~ 125/600 = 21 %) shows that the number of additional ACS sources within 2” is higher than in a comparison sample with the same magnitude distribution as the sample of optical IDs (51 vs 42)

The excess of close pairs around X-ray sources is therefore 9 +- 7, not statistically significant, yet (to be completed on the total sample)

In any case, this analysis suggests that possible effects relating X-ray enhancement to on-going interactions, if present, are effective for a small fraction (< 10% ?) of the X-ray sources.