1. Variability: who cares? or…. Photometric redshift for XMM-COSMOS sources M.Salvato, G. Hasinger, O. Ilbert, G. Zamorani, M.Brusa + COSMOS collaboration Salvato et al. 2009,ApJ, accepted

2. In order to better understand the role (if any) of the AGN phase in Galaxy evolution, a complete CENSUS of AGN is crucial. get them all : Due to the interplay between host and Active Nucleous, No criterion can exist that can identify all AGN using a single waveband (i.e. see talks at this conference). get the right redshift: most of the sources are faint and we must rely on photometric redshifts.

3. even for Xray selected AGN usually, for z<1, the accuracy is not better than 0.06 (after removing 20% of outliers...) …or, in other words, something linke this…

4. Our results: I + AB <22.5 I + AB >22.5

5. Our results: I + AB <22.5 I + AB >22.5

6. Our results: I + AB <22.5 I + AB >22.5.

7. HOW? Correction for variability New templates Tons of photometric points WHAT IS MORE IMPORTANT ?

8. SDSS SUBARU BB IB 1 IB 2 About 2/5 of the XMM sample has clearly detected long term variability

9. Sources vary in a unpredictable way ? Additional ~1000 non X-ray detected galaxies are varying and there are currently under investigation currently under investigation

10. Templates } QSO2+S0 } TQSO1+I22491 Sy1.8 Sy2 MRK231 QSO S0 I22491 M82 Sp Sb

11. Relevance of templates and variability correction Both factors are crucial to reducing the number of outliers.

12. Among other results: Correct stellar/galaxy separation Correct relation between hardness ratio and SED and variability Correct relation between Xray luminosity and SED

13. QSO selection at high z via Lyman break Siana et al. 2008

15. Normal gals type II type I

16. Thank you! Ilbert et al Salvato et al..

17. SUMMARY Variability effects your work more than you think…