New clues on the evolution of clustering from the K20 and FIRES surveys

Emanuele Daddi ESO

K20 surveyPI: A Cimatti (Arcetri)Collaborators: T. Broadhurst (HUJ) S. Cristiani (ESO)S. D’Odorico (ESO) E. Daddi (ESO)A. 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 surveyPI: 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)

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 0055-26) (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

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K20 redshift distribution

Cimatti et al 2002c

147 galaxies 0.75<z<1.3

A mass-limited sample

M/L ratios from R-K colorsmodel tracks(resembling Cole et al 2001)

Projected correlations

(Davis & Peebles 1981)

10 Mpc cutting scalegamma=1.8

MonteCarlo simulations to determineerrors and assess reliability

Clustering evolution to z~1

Agrees with some estimateBased on photometric Redshifts for K-selectedSamples of comparable depths(e.g. Firth et al. 2002)

Unveiling the nature of EROs

45 EROs to K<19.2

1/3 dusty-SF galaxies

1/3 old stellar populations

1/3 unidentified/unclassified

Cimatti et al 2002a

EROs clustering with two flavours

Old EROs are strongly clustered

Dusty-SF EROs are poorly clustered

Daddi et al 2002

Early- and Late-type Galaxies

Clustering evolution for early-type galaxies

Daddi et al 2001

New measurements:Firth et al 2002Roche et al 2002Miyazaki et al 2002

EROs

Some models

predictions

Moustakas & Somerville 2002

FaintInfraRed Extragalactic Survey

Franx et al 2000, the MessengerRudnick et al 2001Labbe et al 2002, submitted

About 200 ISAAC hours Service Mode (excellent seeing) Js-H-Ks bands

2 fieldsHubble Deep Field South(clustering discussed here)MS1054 Field (see Poster by Forster-Schreiber et al.)

Hubble Deep Field South IJK mosaic

For each Js,H,Ks:About 35 hours Integration timeSeeing 0.45” on final Coadded images

5sigma limits (Vega):

Ks=24.0H=24.8Js=25.9

Labbe et al 2002

Photometric redshifts

Rudnick et al 2001, 2002(in preparation)

WFPC2 imagesF300, F450, F606, F814+FIRES JHK images

Δz = 0.08

Sky and redshift distributions

Broadly agree withKashikawa et al 2003Subaru Deep Field

435 galaxies at K<2440% at z>2

The clustering of K<24 galaxies

Clustering of K-selected galaxies at

2<z<4

J-K color segregation

Comparing to LBGs and SCUBA galaxies

•Existence of a populationwith r >8 at 2<z<4

•Larger clustering with respect to optically selected Galaxies

•Color segregation of clustering

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SEDs of J-K>1.7 galaxies at 2<z<4Evidence for breaks,old populations

Consistent withShapley et al 2001

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 fineSED modeling suggest old stellar pops

Fitting in a CDM scenario

Mo & White 2002

Large occupation numbers required

a population withLarge number densityAnd large clusteringAt z=3 is not predictedIn models (e.g. GIF)

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 clusteringat 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

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