Transcript Observational Data

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
Massive elliptical galaxies are the products of
recent hierarchical merging of pre-existing
disk galaxies taking place largely at z<1.5
with moderate SFRs (eg, Cole et al. 2000).
Near IR wide field imaging is crucial.
Fully assembled massive galaxies
with Evolution
Mass Function
(Baugh
et al. 2002)
Ms>1011Mo at z>2 are extremely
rare.
Previous NIR Image Surveys
1.
2.
3.
4.
5.
6.
Hubble Deep Field North & South 2x5.3 arcmin2
K20 (NTT)
52 arcmin2
Subaru Deep Field (Ks=22.6)
4 arcmin2
Subaru XMM Deep Field (Ks=22.1) 114 arcmin2
Goods (HDF-N & CDF-S)
160 arcmin2
Hubble Ultra Deep Field (NICMOS)
5.8 arcmin2
7. EIS3a-F (Subaru/VLT, Ks=20.8)
8. Daddi-F (Subaru/VLT, Ks=19.0)
900 arcmin2
900 arcmin2
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 : 2002/03/28-31
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 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 : 1999/03/27-30
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
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
780 EROs in Deep3a-F
380 EROs in Daddi-F
240 DRGs in Deep3a-F
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
BzKs
stars
425 BzK in Deep 3a
145 BzK in Daddi-F
B
R
I z’
J
K
BzK(ERO)
ERO
BzK
ERO
BzK
ERO
BzK
ERO
Z=1.5564
ＣＩＶ
VLT Observation of ～300 BzK galaxies
z=1.7495
Ｌｙα
z=2.3894
ＣＩＶ
Ｌｙα
z=2.8453
ＣＩＶ
Photometric vs Spectroscopic Redshift
VLT(ESO)
Photometric Redshift
BzKs
EROs
Photometric Redshift
DRGs
Internal reddening
BzK
ERO
•B-z (the slope of UV spectrum) color E(B-V) of SFGs.
•BzKs are dusty galaxies
Kong, Charlot, Brinchman, Fall (2004)
•ERO: OGs & DGs have different internal reddening.
Stellar Mass
BzKs
Stellar mass
EROs
: 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
Star Formation Rate
UV Flux: 1500A<λ<2800A
NIR spectra (Subaru)
• Dad1901
SFR(Ha)=60 M/yr
SFR(UV)=70 M/yr
• Dad2326
SFR(Ha)=250 M/yr
SFR(UV)=180M/yr
• BzKs have high SFRs
• EROs : OGs/DGs diff.
burst age
reddening
stellar mass
SFR
Culling K-band Luminous, Massive Star Forming Galaxies at z>2
Sky positions of BzKs & EROs
BzKs
EROs
Angular two-point correlation function:
w(q)= (DD-2DR+RR)/RR＝Aq-d
Landy & Szalay (1993)
(d=0.8)
Clustering Properties
Field Galaxies
Field Galaxies
EROs
EROs
BzKs
BzKs
A New Population of near-IR
bright, 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).
• BzKs
–
–
–
–
Summary
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
• LBGs
E(B-V)≤0.3, SFR< 70 M/yr, clustering
Summary
BzK selection is a quite powerful way to separate
star 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>2
are likely to be possible precursors of z～1 passively
evolving 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-for
progenitors of nearby massive ellipticals, close to
their epoch of formation.
What Next?
1) Confirming the High SFRs, High metallicity
2) Contribution to the z>2 SFR Density
3) Understand the link between BzK and Submm Gals
4) CO follow-up
5) Co-evolution of BzK and Massive BHs ………
6) COSMOS, NEP. SXDS, etc to see cosmic variance