culling k-band luminous, massive star forming galaxies at z>2
DESCRIPTION
Culling K-band Luminous, Massive Star Forming Galaxies at z>2. N. ARIMOTO (NAOJ). X.Kong, M.Onodera, C.Ikuta (NAOJ),K.Ohta (Kyoto), N.Tamura (Durham),A.Renzini, E.Daddi (ESO), A.Cimatti (Arcetri), T.Broadhurst (Tel ’ Aviv). Formation of Giant Ellipticals. - PowerPoint PPT PresentationTRANSCRIPT
Culling K-band Luminous, Massive Star Forming Galaxies
at z>2
X.Kong, M.Onodera, C.Ikuta (NAOJ),K.Ohta (Kyoto),
N.Tamura (Durham),A.Renzini, E.Daddi (ESO), A.Cimatti (Arcetri), T.Broadhurst (Tel’Aviv)
N. ARIMOTO (NAOJ)
Formation of Giant Ellipticals
Massive elliptical galaxies are the products ofrecent hierarchical merging of pre-existingdisk galaxies taking place largely at z<1.5 with moderate SFRs (eg, Cole et al. 2000).
Mass Function Evolution (Baugh et al. 2002)
Fully assembled massive galaxies with Ms>1011Mo at z>2 are extremely rare.
Near IR wide field imaging is crucial.
Previous NIR Image Surveys
1. Hubble Deep Field North & South 2x5.3 arcmin2
2. K20 (NTT) 52 arcmin2
3. Subaru Deep Field (Ks=22.6) 4 arcmin2
4. Subaru XMM Deep Field (Ks=22.1) 114 arcmin2
5. Goods (HDF-N & CDF-S) 160 arcmin2
6. Hubble Ultra Deep Field (NICMOS) 5.8 arcmin2
7. EIS3a-F (Subaru/VLT, Ks=20.8) 900 arcmin2
8. Daddi-F (Subaru/VLT, Ks=19.0) 900 arcmin2
Subaru/Sup-Cam Observation
ESO Imaging Survey (EIS Deep 3a) FieldRA=11:24:50, DEC=-21:42:00 (J2000.0)
Subaru/Suprime-Cam BRIz’: 2003/03/02-04NTT/SOFI JK : 2002/03/28-31 BRIz’ (900 arcmin^2) 3σ in 2”(AB) B(AB)=27.46 R(AB)=26.87 I(AB)=26.56 z’(AB)=26.07
JK (500, 380 arcmin^2) 3σ in 2”(AB) J(AB)=23.40, Ks(AB)=22.70
Subaru/Sup-Cam Observation
Daddi FieldRA=14:49:29, DEC=09:00:00 (J2000.0)
Subaru/Suprime-Cam BIz’: 2003/03/02-04WHT R : 1998/03/19-21NTT/SOFI K : 1999/03/27-30 BRIz’ (900 arcmin^2) 3σ in 2”(AB) B(AB)=26.59 R(AB)=25.64 I(AB)=25.62 z’(AB)=25.31
K (715 arcmin^2) 3σ in 2”(AB) Ks(AB)=20.91
K-band Galaxy Number Counts
K-selected High-z Galaxies
780 EROs in Deep3a-F380 EROs in Daddi-F240 DRGs in Deep3a-F
1. Extremely Red Objects (EROs) McCarthey et al (1992) R-K>5.0, I-K>4.0, z>1.0, Old Passive & Dusty Star-Forming Galaxies
2. Distant Red Galaxies (DRGs) Frank et al. (2003) J-K>2.3, z>2
New Galaxy Population (BzKs)
Daddi et al. (2005): BzK=(z-K)AB-(B-z)AB>-0.2
BK20=BEIS zK20=zEIS-0.16
High-z galaxies in our fields
Star-forming galaxies at z>1.4
(BzKs) Old galaxies at z>1.4: PEGs
stars
BzKs
425 BzK in Deep 3a145 BzK in Daddi-F
B R I z’ J K
BzK(ERO) BzK BzK BzK
ERO ERO ERO ERO
Z=1.5564
VLT Observation of ~ 300 BzK galaxies
CIV
z=1.7495
z=2.3894
CIV
Ly α
z=2.8453Ly α
CIV
Photometric vs Spectroscopic Redshift
VLT(ESO)
Photometric Redshift
BzKs
EROs
Photometric Redshift
DRGs
Internal reddening
•B-z (the slope of UV spectrum) color E(B-V) of SFGs.
•BzKs are dusty galaxies
•ERO: OGs & DGs have different internal reddening.
Kong, Charlot, Brinchman, Fall (2004)
BzK ERO
Stellar Mass
Stellar mass : based on multi-color photometry
EROs and BzKs are similar (on average)
30% BzKs & EROs : M>1.0E11M @ Deep3a-F Klim=20.2 mag
55% BzKs & EROs : M>1.0E11M @ Daddi-F Klim=18.8 mag
BzKs EROs
Star Formation Rate
NIR spectra (Subaru)• Dad1901
SFR(Ha)=60 M/yr
SFR(UV)=70 M/yr
• Dad2326SFR(Ha)=250 M/yr
SFR(UV)=180M/yr
• BzKs have high SFRs
• EROs : OGs/DGs diff.
UV Flux: 1500A<λ<2800A
burst age reddening
stellar mass SFR
Culling K-band Luminous, Massive Star Forming Galaxies at z>2
Sky positions of BzKs & EROs
Angular two-point correlation function: Landy & Szalay (1993)
w(q)= (DD-2DR+RR)/RR = Aq-d (d=0.8)
BzKs EROs
Clustering Properties
Field Galaxies Field Galaxies
EROs EROs
BzKs BzKs
A New Population of near-IRbright, z ~ 2 Galaxies
K>20 HST/ACS F435W, F850LP & K-band (VLT+ISAAC)
A sample of 9 galaxies at 1.7<z<2.23 with bright K-band magnitudes 18.7<K<20 has recently been discovered (Daddi et al. 2003, astro-ph/0308456).
Summary• BzKs
– High internal reddening : E(B-V) ~ 0.5– strong star formation : SFR ~ 200 M/yr– Massive galaxies : >30 % (K=20)
M>1.0E11M – Strong 2-D clustering
• EROs (R-K>5) : DGs & OGs– OGs: passive galaxies– DGs: some of them are BzKs– OGs have low SFRs– Strong clustering and massive
• LBGsE(B-V)≤0.3, SFR< 70 M/yr, clustering
Summary
BzK selection is a quite powerful way to separatestar forming galaxies at 1.4<z<2.5.
BzKs are different from LBGs (low extinction, low SFR).Some BzKs are dusty EROs (high extinction, low SFR),but most of BzKs are not EROs.
K-band luminous, massive, high-SFRs galaxies at z>2are likely to be possible precursors of z ~ 1 passivelyevolving EROs and z=0 elliptical galaxies.
Submm galaxies are sub-populations of BzKs with extremely high SFRs and metallicities.
Conclusions
We have discovered a new population of reddened, vigorous star-forming massive galaxies at z>2.Their masses, likely extremely high star formation rates, HST/ACS morphologies, clustering properties,all suggest that they may be the long-sought-forprogenitors of nearby massive ellipticals, close totheir epoch of formation.What Next?1) Confirming the High SFRs, High metallicity2) Contribution to the z>2 SFR Density3) Understand the link between BzK and Submm Gals4) CO follow-up5) Co-evolution of BzK and Massive BHs ………6) COSMOS, NEP. SXDS, etc to see cosmic variance