clustering of bzk-selected galaxies in the cosmos field
DESCRIPTION
Clustering of BzK-selected galaxies in the COSMOS field. Xu KONG ([email protected]) collaborators ： A. Renzini, E. Daddi, N. Arimoto, A. Cimatti ， COSMOS team. 2006-03-27 @ Venice . - PowerPoint PPT PresentationTRANSCRIPT
Clustering of BzK-selected galaxies in the COSMOS field
Xu KONG([email protected])
collaborators ： A. Renzini, E. Daddi, N. Arimoto, A. Cimatti ， COSMOS team
2006-03-27 @ Venice
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 posterKong et al. 2006, ApJ, 638, 72
– COSMOS : 2 deg2 NIR survey (BzKs/EROs)
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
RA: 149.415- 150.825
DEC: 1.500 – 2.910
3. Photometric Catalog
NIR : Ks band
33670 gal.
BzKs & EROs
K-band number counts
4.1 Selection of BzKsDaddi et al. (2004, ApJ, 617,746)
K20 Survey： VLT Large Program– 50. arcmin2
– ~ 500 spectra– SFGs BzK> -0.2
BzK=(z-K)AB-(B-z)AB
BzK >-0.2 : sBzKs
BzK<-0.2 & z-K>2.5 : pBzKs
sBzKs pBzKs
4.1 Selection of BzKs
BzK=(z-K)AB-(B-z)AB
BzK >-0.2 : sBzKs BzK<-0.2 & z-K>2.5 : pBzKs
sBzKs pBzKs
CWW templatesBC03 templates
4.2 Selection of EROsR-K>5 (Vega)
R-K>3.35 (AB)
ip-K>2.45
(AB)
4.3 High-z Galaxies in COSMOSsBzKs: 1287star-forming galaxies @ z>1.4
pBzKs:195old galaxies @ z>1.4
EROs: 5090 z~1 galaxies (OGs/DGs)
Stars in COSMOS
Stars in K20
low~z galaxies
4.3 High-z Galaxies in COSMOSsBzKs: 1287star-forming galaxies @ z>1.4
pBzKs:195old galaxies @ z>1.4
EROs: 5090 z~1 galaxies (OGs/DGs)
Stars in COSMOS
Stars in K20
low~z galaxies
4.4 number counts of high-zn.c. of sBzKs:same slope; steep
n.c. of EROs:break
Field galaxies,sBzKs, EROs : similar
pBzKs: different why ?? B-band shallow?
5.1 Clustering of galaxies
EROs: 0.77/arcmin^2sBzKs:0.195/arcmin^2
5.2 Clustering of galaxiesClustering 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
Landy & Szalay (1993) (DD-2DR+RR)/RR＝ A
Angular 2-point correlation function
BzKs are strong clustering!
5.3 Clustering of galaxiesClustering 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
6.1 Photometric Redshift
BzK selection is a quite powerful way to separate galaxies at 1.4<z<2.5
EROs
sBzKs
6.1 Photometric Redshift
6.2 E(B-V) SFR Mass• sBzKs : z~1.8 (Daddi. et al.)
• K <19.2
– B-zUV SlopeE(B-V) • sBzKs are dusty galaxies,
E(B-V) ~ 0.42
– B band 1600ASFR• sBzKs have high SFRs, SF
R ~ 430 M/yr
– SED fitting M*
• Most BzKs are massive galaxies, M ~ 1.5E11 M
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
sBzKs
EROs
6.3 Morphology
sBzKs: irregular
EROs : E/S0
Conclusion• BzKs (K<19.2)
– High redshift 1.4<z<2.5– high internal reddening E(B-V)~0.45– strong star formation SFR~400 M/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!
B>27.5