1. New clues on the evolution of clustering from the K20 and FIRES surveys
Emanuele Daddi
ESO
K20 survey
PI: A Cimatti (Arcetri)
Collaborators:
T. Broadhurst (HUJ) S. Cristiani (ESO)
S. D’Odorico (ESO) E. Daddi (ESO)
Fontana (Roma) E. Giallongo (Roma)
R. Gilmozzi (ESO) N. Menci (Roma)
M. Mignoli (Bologna) F. Poli (Roma)
L. Pozzetti (Bologna) P. Saracco (Milano)
J. Vernet (Arcetri) G. Zamorani (Bologna)
FIRES survey
PI: M. Franx (Leiden)
Collaborators:
I. Labbe (Leiden) A. Moorwood (ESO)
H.W. Rix (MPIA) H. Rottgering (Leiden)
G. Rudnick (MPA) P. van Dokkum(Yale)
N. Forster-Schreiber (Leiden)
P. van der Werf (Leiden)

2. Spectroscopic study of a large sample of
The K20 survey
Spectroscopic study of a large sample of
K-selected galaxies
ESO “large program” 17 VLT nights
546 objects with Ks<20 from two fields (CDFS and ) (unique selection criterium)
Total surveyed area: 52 arcmin
Optical & NIR spectroscopy (FORS1, FORS2,ISAAC)
474 objects with spectroscopic redshift
1/3 galaxies at z>1 2

3. K20 redshift distribution
Cimatti et al 2002c
147 galaxies 0.75<z<1.3

4. A mass-limited sample M/L ratios from R-K colors model tracks
(resembling Cole et al 2001)

5. Projected correlations
(Davis & Peebles 1981)
10 Mpc cutting scale
gamma=1.8
MonteCarlo simulations
to determine
errors and assess reliability

6. Clustering evolution to z~1
Agrees with some estimate
Based on photometric
Redshifts for K-selected
Samples of comparable depths
(e.g. Firth et al. 2002)

7. Unveiling the nature of EROs
Cimatti et al 2002a
45 EROs to K<19.2
1/3 dusty-SF galaxies
1/3 old stellar populations
1/3 unidentified/unclassified

8. EROs clustering with two flavours
Old EROs are strongly clustered
Dusty-SF EROs are poorly clustered
Daddi et al 2002

9. Early- and Late-type Galaxies

10. Clustering evolution for early-type galaxies
Daddi et al 2001
New measurements:
Firth et al 2002
Roche et al 2002
Miyazaki et al 2002
EROs

11. Some models predictions
Moustakas & Somerville 2002

12. Faint Infra Red Extragalactic Survey
About 200 ISAAC hours
Service Mode (excellent seeing)
Js-H-Ks bands
2 fields
Hubble Deep Field South
(clustering discussed here)
MS1054 Field (see Poster by
Forster-Schreiber et al.)
Franx et al 2000, the Messenger
Rudnick et al 2001
Labbe et al 2002, submitted

13. Hubble Deep Field South IJK mosaic
For each Js,H,Ks:
About 35 hours
Integration time
Seeing 0.45” on final
Coadded images
5sigma limits (Vega):
Ks=24.0
H=24.8
Js=25.9
Labbe et al 2002

14. Photometric redshifts
Rudnick et al 2001, 2002
(in preparation)
WFPC2 images
F300, F450, F606, F814 +
FIRES JHK images
Δz = 0.08

15. Sky and redshift distributions
Broadly agree with
Kashikawa et al 2003
Subaru Deep Field
435 galaxies at K<24
40% at z>2

16. The clustering of K<24 galaxies

17. Clustering of K-selected galaxies at 2<z<4
J-K color segregation

18. Comparing to LBGs and SCUBA galaxies
Existence of a population
with r >8 at 2<z<4
Larger clustering with
respect to optically
selected Galaxies
Color segregation of
clustering o

19. SEDs of J-K>1.7 galaxies at 2<z<4
Evidence for breaks,
old populations
Consistent with
Shapley et al 2001

20. Redshift confirmations
There are so far 6 confirmed z>2 galaxies
selected with the reddest J-K>2.3 colors in
FIRES (van Dokkum et al, in preparation)
Photometric redshifts generally work fine
SED modeling suggest old stellar pops

21. Fitting in a CDM scenario
Mo & White 2002
Large occupation
numbers required
a population with
Large number density
And large clustering
At z=3 is not predicted
In models (e.g. GIF)

22. Formation of ellipticals ? Some speculations
If left evolve without merging, produce r >10 at z=0
No population exist with so large clustering and number density
They have to merge, reducing number density and clustering
at short scales
(likely, because of large grouping/occupation numbers)
Forming ellipticals at z>2, already relatively old,
in multiple mergings ?
Indeed, K20 has shown that the current formation paradigm
(spheroidal formation in nearly equal sized merging spirals)
has serious drawbacks:
fails number density of red galaxies at z>1 (EROs)
underpredict the abundance of z>1 luminous galaxies o