A Wide Area Survey for High-Redshift Massive Galaxies Number Counts and Clustering of BzKs and EROs X.Kong, M.Onodera, C.Ikuta (NAOJ), K.Ohta (Kyoto), N.Tamura (Durham), A.Renzini, E.Daddi, L. Da Costa (ESO), A.Cimatti (Arcetri), T.Broadhurst (Tel Aviv), L.F.Olsen (Cote d Azur) N. ARIMOTO (NAOJ) Kong et al. (2006), Astro-ph/ , ApJ in press Formation of Giant Ellipticals Massive ellipticals are the products of recent hierarchical merging of disk galaxies taking place largely at z Mo at z>2 are extremely rare. Massive Galaxies in the Redshift Desert (z>1.3) Glazebrook et al. (2004)Cimatti et al. (2004) Previous Spectroscopic Surveys 1)K20 (Cimatti et al. 2002) 52 arcmin 2 2)HDFN (Ferguson et al. 2000) 5.3 arcmin 2 3)GOODS (Giavalisco et al. 2004) 160 arcmin 2 4)HST/ACS UDF (Yan et al 2004) 12 arcmin 2 5)GDDS (McCarthy et al 2004) 121 arcmin 2 2 (Steidel et al 2004) 100 arcmin 2 Massive galaxies are quite rare and likely highly clustered at all redshifts, hence small areas such as those explored so far are subject to large cosmic variance. EIS Deep 3a Survey We have undertaken a fairly deep, wide-field imaging with the Subaru/Suprime-Cam of two fields of 900 arcmin 2 each for part of which near-IR data are available from ESO NTT observations. 7. EIS3a-F (Subaru/NTT, Ks=20.8) 320 arcmin 2 8. Daddi-F (Subaru/NTT, Ks=19.0) 600 arcmin 2 The prime aim of this survey is to understand how and when the present-day massive galaxies formed. To this end, the imaging observations have been optimized for the use of optical/near-infrared multi-colour selection criteria to identify both star forming and passive galaxies (BzK selection). Kong et al. (2006) astro- ph/ Subaru/Sup-Cam Observation Daddi Field RA=14:49:29, DEC=09:00:00 (J2000.0) Subaru/Suprime-Cam BIz : 2003/03/02-04 WHT R : 1998/03/19-21 NTT/SOFI K : 1999/03/ BRIz (940 arcmin 2 ) 3 in 2 (AB) B(AB)=26.59 R(AB)=25.64 I(AB)=25.62 z (AB)=25.31 K (600 arcmin 2 ) 3 in 2 (AB) Ks(AB)=20.91 940arcmin 2 600arcmin 2 Subaru/Sup-Cam Observation ESO Imaging Survey (EIS Deep 3a) Field RA=11:24:50, DEC=-21:42:00 (J2000.0) Subaru/Suprime-Cam BRIz : 2003/03/02-04 NTT/SOFI JK : 2002/03/ BRIz (940 arcmin 2 ) 3 in 2 (AB) B(AB)=27.46 R(AB)=26.87 I(AB)=26.56 z (AB)=26.07 JK (320 arcmin 2 ) 3 in 2 (AB) J(AB)=23.40, Ks(AB)=22.70 940arcmin 2 320arcmin 2 K-band Galaxy Number Counts Differential K-band Galaxy Counts BzK-Selected Galaxies (K20) BzK=(z-K)-(B-z)>-0.2 (Daddi et al 2004, ApJ 617, 746) (z-K)>2.5 Why BzK-selection if efficient for culling star-forming and passive galaxies at 1.41.4: (pBzKs) stars BzKs BzK(ERO) BzK BzK BzK ERO ERO 387 sBzK121 pBzK 108 sBzK48 pBzK 513 ERO 337 EROs Star/Galaxy Separation (z-K) AB -0.3(B-z) AB 5 level). The correlation between E(B-V) and stellar mass Is likely to be intrinsic, with more massive galaxies being also more absorbed (>7 level). Given the previous two correlations, not surprisingly we also find a correlation between SFR and stellar masses (>4 level). The upper edge in the SFR vs M * appear to be intrinsic, showing a limit on the maximum SFR that can be present in a galaxy of a given mass. Brinchmann et al (2004) z 2 were 10 times larger than today. Downsizing Effects? At z=0 the vast majority of massive galaxies (M * >10 11 Mo) are passively evolving red galaxies, while at z 2 actively star forming (sBzKs) and passive (pBzKs) galaxies exist in similar numbers, and most massive galaxies tend to be the most actively star forming galaxies. This can be seen as yet another manifestation of the downsizing effect, with massive galaxies completing their star formation at an earlier epoch compared to less massive galaxies, which instead have more prolonged star formation. Contribution of sBzKs to SFRD 25% AGN Contamination SFRD=0.06 Mo/yr/Mpc 3 for sBzKs in Deep3a-F (K Vega