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. In order to better understand the role (if any) of the
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M.Salvato, G. Hasinger, O. Ilbert, G. Zamorani, M.Brusa
Salvato et al. 2009,ApJ, accepted
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.
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…
WHAT IS MORE IMPORTANT ?
About 2/5 of the
XMM sample has
long term variability
Sources vary in a unpredictable way
Additional ~1000 non X-ray detected
galaxies are varying and there are
currently under investigation
Relevance of templates and variability correction
Both factors are crucial to reducing the number of outliers.
QSO selection at high z via Lyman break
Siana et al. 2008
Normal gals type II type I
Ilbert et al Salvato et al.
Variability effects your work more than you think…