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Clustering of BzK-selected galaxies in the COSMOS field

Clustering of BzK-selected galaxies in the COSMOS field. Xu KONG (xkong@ustc.edu.cn) collaborators ： A. Renzini, E. Daddi, N. Arimoto, A. Cimatti ， COSMOS team. 2006-03-27 @ Venice.

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Clustering of BzK-selected galaxies in the COSMOS field

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  1. Clustering of BzK-selected galaxies in the COSMOS field Xu KONG (xkong@ustc.edu.cn) collaborators： A. Renzini, E. Daddi, N. Arimoto, A. Cimatti，COSMOS team 2006-03-27 @ Venice

  2. 1. Introduction • NIR/Spect. Surveys (good points: k-corrections, dust extinction, instantaneous SFH, stellar mass …) • HDF (2x5.3 arcmin2) UDF (5.76 arcmin2)SDF ( 4.0arcmin2) • K20 (52.0 arcmin2) SXDF (114.0 arcmin2) GOODS (320.0arcmin2) • GDDS GEMS MUNICS • VVDS DEEP2 GMASS • We are working on … • EIS-Deep3a: 900 arcmin2 NIR survey (Deep3a-F,Daddi-F) Prof. Arimoto, Renzini, Daddi talks, Masato poster Kong et al. 2006, ApJ, 638, 72 • COSMOS : 2 deg2 NIR survey (BzKs/EROs)

  3. 2. COSMOS • Fields : RA (J2000) = 10:00:28.6 DEC (J2000) = +02:12:21.0 • Catalog : 2 January 2006 • P. Capak, B. Mobasher, N.Z. Scoville (PI) • released_20060103_photz.cat • i_auto < 25 mag (AB system) : 438278 objects • B_mask=0 : 363670 objects • Sampling: 39960 objects • Area: RA (149.415-150.825); DEC (1.500-2.910) • K_tot<19.2; err_K<0.25; B_mask=0

  4. RA: 149.415- 150.825 DEC: 1.500 – 2.910

  5. 3. Photometric Catalog NIR : Ks band 33670 gal. BzKs & EROs K-band number counts

  6. 4.1 Selection of BzKs Daddi et al. (2004, ApJ, 617,746) K20 Survey：VLT Large Program • 50. arcmin2 • ~ 500 spectra • SFGs BzK> -0.2 sBzKs pBzKs BzK=(z-K)AB-(B-z)AB BzK >-0.2 : sBzKs BzK<-0.2 & z-K>2.5 : pBzKs

  7. 4.1 Selection of BzKs pBzKs sBzKs BC03 templates CWW templates BzK=(z-K)AB-(B-z)AB BzK >-0.2 : sBzKs BzK<-0.2 & z-K>2.5 : pBzKs

  8. 4.2 Selection of EROs R-K>5 (Vega) R-K>3.35 (AB) ip-K>2.45 (AB)

  9. 4.3 High-z Galaxies in COSMOS sBzKs: 1287 star-forming galaxies @ z>1.4 pBzKs:195 old galaxies @ z>1.4 EROs: 5090 z~1 galaxies (OGs/DGs) Stars in COSMOS Stars in K20 low~z galaxies

  10. 4.3 High-z Galaxies in COSMOS sBzKs: 1287 star-forming galaxies @ z>1.4 pBzKs:195 old galaxies @ z>1.4 EROs: 5090 z~1 galaxies (OGs/DGs) Stars in COSMOS Stars in K20 low~z galaxies

  11. 4.4 number counts of high-z n.c. of sBzKs:same slope; steep n.c. of EROs:break Field galaxies,sBzKs, EROs : similar pBzKs: different why ?? B-band shallow?

  12. 5.1 Clustering of galaxies sBzKs:0.195/arcmin^2 EROs: 0.77/arcmin^2

  13. 5.2 Clustering of galaxies • Clustering of field galaxies • Amplitudes ~ published values • Clustering of EROs • A ~ published values • K fainter, A decrease • Clustering of BzKs • A is large • K fainter, A decrease Angular 2-point correlation function Landy & Szalay (1993) w(q)= (DD-2DR+RR)/RR＝Aq-d d=0.8

  14. 5.3 Clustering of galaxies Clustering of field galaxies Amplitudes ~ published values • Clustering of EROs • A ~ published values • K fainter, A decrease • Clustering of BzKs • A is large • K fainter, A decrease BzKs are strong clustering!

  15. 6.1 Photometric Redshift sBzKs EROs BzK selection is a quite powerful way to separategalaxies at 1.4<z<2.5

  16. 6.1 Photometric Redshift

  17. 6.2 E(B-V) SFR Mass • sBzKs : z~1.8 (Daddi. et al.) • K <19.2 • B-zUV SlopeE(B-V) • sBzKs are dusty galaxies, E(B-V) ~ 0.42 • B band 1600ASFR • sBzKs have high SFRs, SFR ~ 430 M/yr • SED fitting M* • Most BzKs are massive galaxies, M ~ 1.5E11 M

  18. 6.3 SFRD/MD at redshift~2 • For K<19.2 mag. • SFRD at z~2 : 0.037 M/yr • Mass densities : logρ*=7.1 M Mpc-3

  19. sBzKs 6.3 Morphology EROs sBzKs: irregular EROs : E/S0

  20. Conclusion • BzKs (K<19.2) • High redshift 1.4<z<2.5 • high internal reddening E(B-V)~0.45 • strong star formation SFR~400M/yr • Massive galaxies. >80％ M>1.0E11M • Strong 2-D clustering A(BzKs)≥A(EROs) BzKs are likely to be possible precursors of z～1 EROs and z=0 elliptical galaxies. • We will do on COSMOS … • High-z cluster candidates • Morphology of BzKs & EROs • Hubble sequence at z~2 THANKs!

  21. B>27.5

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