Variability: who cares? or…. Photometric redshift for XMM-COSMOS sources M.Salvato, G. Hasinger,...
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Transcript of Variability: who cares? or…. Photometric redshift for XMM-COSMOS sources M.Salvato, G. Hasinger,...
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 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…
Our results:
I+AB<22.5
I+AB>22.5
Our results:
I+AB<22.5
I+AB>22.5
Our results:
I+AB<22.5
I+AB>22.5
.
HOW?
• Correction for variability• New templates• Tons of photometric points
WHAT IS MORE IMPORTANT ?
SDSS
SUBARU
BB IB1IB2
About 2/5 of the XMM sample hasclearly detectedlong term variability
Sources vary in a unpredictable way
?
Additional ~1000 non X-ray detected
Additional ~1000 non X-ray detected
galaxies are varying and there are
galaxies are varying and there are
currently under investigation
currently under investigation
Templates
}QSO2+S0
}TQSO1+I22491
Sy1.8Sy2
MRK231
QSO
S0
I22491
M82
Sp
Sb
Relevance of templates and variability correction
Both factors are crucial to reducing the number of outliers.
Among other results:
• Correct stellar/galaxy separation
• Correct relation between hardness ratio and SED and variability
• Correct relation between Xray luminosity and SED
QSO selection at high z via Lyman break
Siana et al. 2008
Normal gals type II type I
Thank you!
Ilbert et al Salvato et al.
.
SUMMARY
Variability effects your work more than you think…
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