Exploring massive galaxy evolution with the UKIDSS Ultra-deep Survey
Ross McLure, Michele Cirasuolo, Jim Dunlop (Edinburgh), Omar Almaini, Sebastien Foucaud (Nottingham),
OutlineOutline Understanding galaxy formationUnderstanding galaxy formation Why we need deep NIR surveysWhy we need deep NIR surveys UKIDSS & the Ultra Deep UKIDSS & the Ultra Deep
SurveySurvey UDS science results (Edinburgh)UDS science results (Edinburgh) The future: UDSThe future: UDSzz + + spspUDSUDS
The motivation for UDS:
Understanding galaxy formation
ΛCDM cosmological model in excellent agreement with widerange of observations:
e.g. CMB, galaxy clustering, SN, element abundances, Cepheid distance scale, stellar ages, baryon fraction in clusters, etc…
Understanding galaxy formation
Cosmology
Understanding galaxy formation
still don’t understand galaxy formation
Cosmology
Semi-analytic Galaxy Formation Semi-analytic Galaxy Formation ModelsModels
+Messy physics
(gas cooling, star-formation,AGN, dust, feedback etc…)
N-body merger trees
=
Understanding galaxy formation
SAMs have been very successful in some regards
traditionally SAMs predicted very few old/red/massive galaxiesat high-redshift (i.e. z>1)
HOWEVER
Semi-analytic Galaxy Formation Semi-analytic Galaxy Formation ModelsModels
+Messy physics
(gas cooling, star-formation,AGN, dust, feedback etc…)
N-body merger trees
=
Understanding galaxy formation
Over the last 5 years, near-infrared surveys have discovered substantial populations of evolved galaxies at z>1 which are missed
by optical surveys, and not accounted for by SAMs (e.g. EROs, DRGs etc)
What are they?What are they?
~50% old, passive systems~50% old, passive systems ~50% dusty starburst~50% dusty starburst Strongly clustered Strongly clustered High space densityHigh space density
Many old, massive galaxiesMany old, massive galaxies
already in place at z~1-1.5already in place at z~1-1.5
e.g. Daddi et al. 2002; Roche, Almaini et al. (2002), Cimatti et a. (2003); Roche, Dunlop & Almaini (2003), Somerville et al. (2003)
EROs (Extremely Red Objects)EROs (Extremely Red Objects)
– 6 arcmin6 arcmin2 2 – VLT ISAAC imaging (JHK)VLT ISAAC imaging (JHK)– K~23.5 (Vega)K~23.5 (Vega)
Find population consistentFind population consistent
with very red z>2 galaxies.with very red z>2 galaxies.
““Distant Red Galaxies (DRGs)”Distant Red Galaxies (DRGs)”
J - K > 2.3J - K > 2.3
Labbe et al. 2002, Franx et al. 2003,
Rudnick et al. 2003, Van Dokkum et al. 2005, Wuyts et al. 2007
Pushing IR surveys to z>2Pushing IR surveys to z>2FIRES - a glimpse of what UDS will achieveFIRES - a glimpse of what UDS will achieve
100 hrs on VLT in 0.5” seeing
Understanding galaxy formationVarious high-z populations (EROs, DRGs, BzKs etc) all justsub-sets of substantial population of massive galaxies at high-z
Better to study evolution of entire galaxypopulation down to a given K-band limit
K<23.5(AB) sample in GOODS-S, Caputi et al. (2006)
This study, and others, demonstrated that ~80% of most massive galaxies are in place at z=1, but that only ~10% are in place at z=3
Epoch of massive galaxy formation is 1<z<3
Example: how many >1011 solar mass galaxies are in place at high redshift?
Conclusion:
The need for deep infrared surveys
Optical surveys sample rest-frame UV at high-z
Deep near-IR surveys vital for a complete census at z>1
1. Biased against high-z galaxies obscured by dust 2. Bias against high-z galaxies with old stellar
populations 3. Provide poor estimate of stellar mass
OutlineOutline Understanding galaxy formationUnderstanding galaxy formation Why we need deep NIR surveysWhy we need deep NIR surveys UKIDSS & the Ultra Deep UKIDSS & the Ultra Deep
SurveySurvey UDS science results (Edinburgh)UDS science results (Edinburgh) The future: UDSThe future: UDSzz + + spspUDSUDS
UKIDSS : UKIRT Infrared Deep Sky Survey
UKIRT (Mauna Kea, Hawaii)
Wide-field Camera (WFCAM)
UKIDSS design (5 surveys)UKIDSS design (5 surveys)
Ultra Deep Survey UDS JHK K=23.0 0.77 deg2 ExGal
Deep Extragalactic Survey DXS JK K=21.0 35 deg2 ExGal
Galactic Plane Survey GPS JHK K=19.0 1800 deg2 Gal
Galactic Clusters Survey GCS ZYJHK K=18.7 1600 deg2 Gal
Large Area Survey LAS YJHK K=18.4 4000 deg2 ExGal
UKIRT Infrared Deep Sky Survey
WFCAM Focal Plane configuration
• Four 2048x2048 pixel Rockwell detectors• 0.4” pixels give 0.2 square degree in single shot• Four exposures give filled 0.8 square degrees
0.88
deg
.
UDS is one WFCAM tile at RA = 02 18 00, Dec = -05 00 00 (equatorial, 8hrs away from COSMOS field)
The UKIDSS Ultra-Deep SurveyThe UKIDSS Ultra-Deep Survey Depths achieved so far:
(AB, 5σ, 2" apertures))
0.8
8 d
eg
.
EDREDR:: K=22.6, J=22.6 K=22.6, J=22.6 (~12 hours)(~12 hours)
Year 1:Year 1: K=23.5, J=23.6 K=23.5, J=23.6 (~85 hours)(~85 hours)
Already deepest IR survey over this area… Already deepest IR survey over this area…
Year 3:Year 3: K=24.2, H=24.0, J=24.3 K=24.2, H=24.0, J=24.3 (~250 hours)(~250 hours)
Year 2:Year 2: K=23.7, H=23.5, J=23.8 K=23.7, H=23.5, J=23.8
(~120 hours)(~120 hours)
The UKIDSS Ultra-Deep SurveyThe UKIDSS Ultra-Deep Survey Depths achieved so far:
(AB, 5σ, 2" apertures))
0.8
8 d
eg
.
EDREDR:: K=22.6, J=22.6 K=22.6, J=22.6 (~12 hours)(~12 hours)
Year 1:Year 1: K=23.5, J=23.6 K=23.5, J=23.6 (~85 hours)(~85 hours)
Year 3:Year 3: K=24.2, H=24.0, J=24.3 K=24.2, H=24.0, J=24.3 (~250 hours)(~250 hours)
Year 2:Year 2: K=23.7, H=23.5, J=23.8 K=23.7, H=23.5, J=23.8
(~120 hours)(~120 hours)
Year 3 data becomes ESO public in JulyYear 3 data becomes ESO public in July
x20
x400
Unique depth+area in NIR plus strong + multi-wavelength coverage
The UKIDSS Ultra-Deep SurveyThe UKIDSS Ultra-Deep Survey
The Subaru/XMM Deep The Subaru/XMM Deep FieldField
RA = 02 18 00, Dec = -05 00 00
Optical Subaru: B=28.2, V=27.6, R=27.5, i’=27.2, z’=26.3
Optical CFHT:ugriz
X-ray:XMM-Newton 100ks + 6x50ks
Radio:VLA 12 μJy rms 1.4Ghz
Spitzer: Spitzer SWIRE 3.6-160μm(NEW: Legacy survey)
Submm:SHADES 8mJy (850μm)
GALEX:FUV+NUV
The UKIDSS Ultra-Deep SurveyThe UKIDSS Ultra-Deep Survey
FUV+NUV+ugri+BVRi’z’+JHK+IRAC1+IRAC2
σ = 0.03
~1% of outliers
Importance of multiwavelength data : photometric redshifts
• Photometric redshifts are based on template fitting
• Currently using 16 broad-band filters:
• Currently ~3000 spectroscopic redshifts available
Photometric redshifts by Michele Cirasoulo (Edinburgh)
currently impossible to get spectra for > 100,000 objects
(many more coming from FORS2/VIMOS +FMOS)
When are galaxies assembled?When are galaxies assembled?
- detailed luminosity functions from 1<z<6- detailed luminosity functions from 1<z<6
High-z galaxy mass functionHigh-z galaxy mass function
- Model SEDs (- Model SEDs (GALEX+CFHT+SUBARU+UKIRT+SPITZERGALEX+CFHT+SUBARU+UKIRT+SPITZER))
How do galaxy properties evolve with time?How do galaxy properties evolve with time?
- Formation of the red sequence- Formation of the red sequence
- Morphologies, prevalence of AGN, - Morphologies, prevalence of AGN, starformation ratestarformation rate
Large-scale structureLarge-scale structure
- provides probe of dark matter halos- provides probe of dark matter halos
- evolution of clustering & bias- evolution of clustering & bias
Key goals of the Ultra-Deep SurveyKey goals of the Ultra-Deep Survey
Science results from the UDS
1. Galaxy colour bimodality out to z~2
2. K-band luminosity function out to z~4
3. Obscured galaxy formation (sub-mm)
4. Massive galaxies at 4.5<z<6.5
Baldry et al. 2004
Early type
Late type
Well studied in the local Universe
Visvanathan & Sandage 1977; Bower et al. 1992;
Starteva et al. 2001; Baldry et al. 2004
The evolution of colour bimodalityThe evolution of colour bimodalityCirasuolo et al. 2007
Bell et al. 2004 Combo-17 R < 24
Well studied in the local Universe
Visvanathan & Sandage 1977; Bower et al. 1992;
Starteva et al. 2001; Baldry et al. 2004
Extended up to z ≈ 1
Bell et al. 2004; Willmer et al. 2005;
Franzetti et al. 2006
The evolution of colour bimodalityThe evolution of colour bimodalityCirasuolo et al. 2007
The evolution of colour bimodalityThe evolution of colour bimodality
Primary selection in K-band ⇒
No bias against red objects
Red objects present at any redshift
Strength of bimodality
decreases with redshift
Star formation
Reddening
Cirasuolo et al. 2007
Science results from the UDS
1. Galaxy colour bimodality out to z~2
2. K-band luminosity function out to z~4
3. Obscured galaxy formation (sub-mm)
4. Massive galaxies at 4.5<z<6.5
Evolution of the near-IR galaxy LFEvolution of the near-IR galaxy LF>50,000 galaxies with KAB ≤ 23
Local K-band LF
Schechter function with
Luminosity evolution
+
Density evolution
Cirasuolo et al. 2008, arXiv:0804.3471
Comparison with some results in literature
Caputi et al. 2006
Saracco et al. 2006
Pozzetti et al. 2003
Evolution of the near-IR galaxy LFEvolution of the near-IR galaxy LFCirasuolo et al. 2008, arXiv:0804.3471
Comparison with theoretical models
Bower 2006
De Lucia 2007
Monaco 2007
Menci 2006
Nagamine 2006
Evolution of the near-IR galaxy LFEvolution of the near-IR galaxy LFCirasuolo et al. 2008, arXiv:0804.3471
Comparison with theoretical models
Bower 2006
De Lucia 2007
Monaco 2007
Menci 2006
Nagamine 2006
Evolution of the near-IR galaxy LFEvolution of the near-IR galaxy LFCirasuolo et al. 2008, arXiv:0804.3471
next data-release will push one magnitude deeper
Science results from the UDS
1. Galaxy colour bimodality out to z~2
2. K-band luminosity function out to z~4
3. Obscured galaxy formation (sub-mm)
4. Massive galaxies at 4.5<z<6.5
>60% of cosmic star formation history is obscured>60% of cosmic star formation history is obscured
Hughes et al. (1998) Nature, 394, 241
Obscured galaxy formation
Galaxy spectrum at progressively higher redshifts
A clear view from z = 1 to z = 8 (reionization?)Sub-mm astronomy:Sub-mm astronomy:
Obscured galaxy formation
UDS has been observed by SCUBA at 850μm and AzTEC at 1.1mm as part of SHADES Survey
Obscured galaxy formation
Sometimes identification can be trickySometimes identification can be tricky
e.g. SMA follow-up of SXDF850.6e.g. SMA follow-up of SXDF850.6 Iono et al. (2008)Iono et al. (2008)
VLA 1.4 GHz Optical - Subaru
SMA
Finally …….unambiguous K-band ID
SMA on optical SMA on K-band
Demonstrates:
1. power of sub-mm interferometry
2. importance of near-IR data identification & study of host galaxy
S850 > 6 mJy
S850 < 6 mJy
Anti-hierarchical growth?Anti-hierarchical growth?Cirasuolo et al. 2008, in prep
Currently analysing SCUBA+AzTEC sourcesin UDS+LOCKMAN to confirm result
Science results from the UDS
1. Galaxy colour bimodality out to z~2
2. K-band luminosity function out to z~4
3. Obscured galaxy formation (sub-mm)
4. Massive galaxies at 4.5<z<6.5
40
Massive galaxies at 4.5<z<6.5
Selecting galaxies at high redshift Two basic techniques: 1. Lyman-break selection (LBGs)2. Narrow-band selection of Lyman alpha emitters (LAEs)
B V R i z
J H K 3.6μm 4.5μm
41
Massive galaxies at 4.5<z<6.5
Selecting galaxies at high redshift Two basic techniques: 1. Lyman-break selection (LBGs)2. Narrow-band selection of Lyman alpha emitters (LAEs)
B V R i z
J H K 3.6μm 4.5μm
z=5.5 BC model
42
The depth and spatial resolution of theHST ACS imaging in the Ultra Deep Fieldand wider GOODS N+S fields has been crucial
Has allowed high-redshift luminosity functionbe traced as faint as ~0.1 L*
However:
Very small areas (HUDF ~13 arcmin2]
Potential for large cosmic variance, particularly at bright-end of LF
Massive galaxies at 4.5<z<6.5
43
B-drops at z~4
V-drops at z~5
i-drops at z~6
Adapted from Bouwens et al. (2007)
Massive galaxies at 4.5<z<6.5
44
Small area of HST fields means there is virtually no informationbrighter than M*
Massive galaxies at 4.5<z<6.5
McLure et al. 2008, arXiv:0805:1335
Strategy:
•Selected z<26 (AB) catalog from SXDS data (z=6.5 limit)
•Rejected anything formally detected in B-band image (4.5<z<6.5)
•Photometric redshift fitting for all candidates (~6000 objects)
•Used redshift probability function P(z) to construct V/Vmax LF estimate
More inclusive than strict “drop-out” selectionMaximizes available redshift information
Massive galaxies at 4.5<z<6.5
Massive galaxies at 4.5<z<6.5
2. Wide area allows accurate clustering analysis: ro=8 Mpc , halo masses ~ 5x1011M
1. Clear evolution in UV LF from z=5 to z=6 : can’t be evolution in Φ★ alone
Seb Foucaud (Nottingham)
Massive galaxies at 4.5<z<6.5
How do we compare with previous studies?
Massive galaxies at 4.5<z<6.5
Excellent agreement with Bouwens et al. (2007)
Surprising given: greatly differing areas, data & techniques
Massive galaxies at 4.5<z<6.5
ML fits to the combined ground+HST data-sets
M* brightens by ~0.7 magnitudes from z=6 to z=5
No significant evolution of normalization or faint-end slope
Massive galaxies at 4.5<z<6.5
B V R i z
J H K 3.6μm 4.5μm
Stacking analysis: 5<z<6 LBG sample
stacked data for ~750 5<z<6 LBGs
• zphot = 5.43
• Av = 0.0• Age = 400 Myr
• Mass = 1010.0 M
SWIRE data only
Massive galaxies at 4.5<z<6.5
+
Massive galaxies at 4.5<z<6.5
+
BowerDe LuciaCombination of LF and typical M/L allows rough
estimate of stellar mass function/density:
Stellar mass in place by z~5 is ~1x107M Mpc-3
Stellar mass in place by z~6 is ~4x106M Mpc-3
(c.f. Yan et al. 2006; Stark et al. 2007)
OutlineOutline Understanding galaxy formationUnderstanding galaxy formation Why we need deep NIR surveysWhy we need deep NIR surveys UKIDSS & the Ultra Deep UKIDSS & the Ultra Deep
SurveySurvey UDS science results (Edinburgh)UDS science results (Edinburgh) The future: UDSThe future: UDSzz + + spspUDSUDS
Spitzer Legacy Programme: spUDS Spitzer Legacy Programme: spUDS 124 hours IRAC124 hours IRAC168 hours MIPS168 hours MIPS
Spitzer Legacy Programme: Spitzer Legacy Programme: spspUDS UDS 124 hours IRAC124 hours IRAC168 hours MIPS168 hours MIPS
Full field mosaic with IRAC 3.6,4.5,5.8,8.0 microns5σ limit of 24.2(AB) at 3.6 microns(7 times deeper than current SWIRE coverage)
Full field mosaic with MIPS 24 microns5σ limit of 18.8(AB) (4 times deeper than current SWIRE coverage)
Science drivers:1. Reliable determination of galaxy masses at high-z2. Separation of galaxy populations into passive/starforming
Observations completed end of Feb 2008
Spitzer Legacy Programme: spUDS Spitzer Legacy Programme: spUDS 124 hours IRAC124 hours IRAC168 hours MIPS168 hours MIPS
Spitzer Legacy Programme: spUDS Spitzer Legacy Programme: spUDS 124 hours IRAC124 hours IRAC168 hours MIPS168 hours MIPS
IRAC+MIPS world data release in ~6 months
ESO Large Programme: UDSz ESO Large Programme: UDSz 93 hours VIMOS93 hours VIMOS
142 hours FORS2142 hours FORS2
When are galaxies assembled?When are galaxies assembled?
- detailed luminosity functions from 1<z<4- detailed luminosity functions from 1<z<4
- high-z mass function - high-z mass function
Large-scale structure Large-scale structure
- - evolution evolution of clustering & biasof clustering & bias
- halo occupation; how many galaxies per dark matter - halo occupation; how many galaxies per dark matter halo?halo?
How do galaxy properties evolve with time?How do galaxy properties evolve with time?
- Formation of the red sequence- Formation of the red sequence
- Influence of environment- Influence of environment
Legacy valueLegacy value
Key goals of UDSzKey goals of UDSz
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
photo-z
8000
6000
4000
2000
0
cou
nt
ESO Large Programme: UDSzESO Large Programme: UDSz
• • K-selected sample to KK-selected sample to KABAB<23 over 0.6 sq degrees<23 over 0.6 sq degrees• Pre-selected with z• Pre-selected with zphotphot>1 (plus control sample)>1 (plus control sample)• Sampling 1/6 galaxies (~4000) • Sampling 1/6 galaxies (~4000)
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
photo-z
8000
6000
4000
2000
0
cou
nt
ESO Large Programme: UDSzESO Large Programme: UDSz
• • K-selected sample to KK-selected sample to KABAB<23 over 0.6 sq degrees<23 over 0.6 sq degrees• Pre-selected with z• Pre-selected with zphotphot>1 (plus control sample)>1 (plus control sample)• Sampling 1/6 galaxies (~4000) • Sampling 1/6 galaxies (~4000)
All galaxies observed in red +blue:All galaxies observed in red +blue:
VIMOS LR-Blue VIMOS LR-Blue VIMOS LR-RedVIMOS LR-Red FORS2 300IFORS2 300I
8 VIMOSPOINTINGS
20 FORS2 POINTINGS
Summary
•The UDS is already the deepest, wide-area NIR survey undertaken
• Excellent multi-wavelength coverage ideal for galaxy evolution studies
• All the Subaru optical and UKIRT-IR data is publicly available
• Large Spitzer legacy programme completed - public in 6 months time
• Large ESO spectroscopic programme on-going
Latest news …Latest news …
An extremely faint quasar at z=6.01
2D GMOS spectrum (courtesy of Chris Willott)Object original identified in McLure et al. (2006)from SXDS plus UDS EDR data
Classified as massive LBG at zphot=5.9+/-0.2
Faintest known quasar at z~6, MUV~ -22 (4 magnitudes fainter than SDSS quasars)
“Seyfert galaxy” at z=6
LAE at z=6.05 from FORS2LAE at z=6.05 from FORS2
In the near future…In the near future…
20 22 24 26 28
z > 1
z < 1
I
5000
4000
3000
2000
1000
0
cou
nt
The size evolution of massive galaxiesMcLure et al. (2007, in prep]
Recent studies ( e.g. Trujillo et al. 2006, Longhetti et al. 2007, Zirm et al. 2007) have concluded that massive galaxies at 1.5<z<2.5 are factor ~4 smaller than their local counterparts.
Appears to rule out simple passive evolutionary history
The size evolution of massive galaxiesMcLure et al. (2007, in prep]
Appears to rule out simple passive evolutionary history
Power of the UKIDSS UDS is that we can now study size evolution of massive galaxies using completesamples of ~5000, M>1011M objects
Recent studies ( e.g. Trujillo et al. 2006, Longhetti et al. 2007, Zirm et al. 2007) have concluded that massive galaxies at 1.5<z<2.5 are factor ~4 smaller than their local counterparts.
The size evolution of massive galaxiesMcLure et al. (2007, in prep]
Complete sample of 5000 M>1011M
galaxies in interval 0.0<z<2.5
Confirm massive galaxies at z~2are smaller than locally, but by less than factor of two
Suggests factor of 1.5-2.0 growth isneeded since z~1.5
Fully consistent with on average one major merger in last 9 Gyrs
Why Deep IR surveys ?Why Deep IR surveys ?
Better tracer of the mass in stars
Less affected by dust extinctionLV
LK
Massive galaxies at z>5
Strategy:
McLure et al., 2006, MNRAS, 372, 357
Exploit large area advantage over previous surveys (0.6 square degrees)Search confined to brightest LBGs at z>5, with z’<25(AB)
Specific aims:
Calculate number density of massive LBGs at z>5, with low cosmic varianceConstrain high-mass end of galaxy mass function at 5<z<6Compare with ΛCDM halo mass function Compare with latest galaxy mass function predictions
• z’<25 (AB), which corresponds to >10σ detections
• Non-detections in B and V-bands (2σ)
• R-z > 3 (ensures redshift z>5)
Selection criteria:
z=5.5, BC model
Massive galaxies at z>5
Massive galaxies at z>5
• Over 0.6 square degree area, 74 objects met initial selection criteria
• SED fitting of remaining candidates
• 65 objects excluded due to plausible low-redshift solutions
(e.g. heavily reddened EROs at z~1, galactic M dwarf stars)
• Final sample consists of only 9 objects
Completeness corrected surface density = 0.005 +/- 0.002 arcmin-2
c.f. HST deep fields surface density = 0.004 +/- 0.004 arcmin-2 (Bouwens et al. 2006)based on single object at z<25ext
• zphot = 5.41
• Av = 0.6• Age = 500 Myr
• Mass = 1.6 x1011.0 M
Example SED fits
• zphot = 5.26
• Av = 0.0• Age = 114 Myr
• Mass = 4 x 1010.0 M
STACKING ANALYSIS
B RV
z`
i`
J 3.6K
Average stack of all 9 LBG candidates, increases depth by ~ 1 magnitudeConfirm non-detections in B and V-bands to limits of B=30.3, V=29.5 (1σ)
STACKING ANALYSIS
Average stack of LBG candidates has mass =1010.7 M
Median stack of LBG candidates has mass = 1011.0 M
SBM03#3 (Bunker et al. 2003)
• Effective volume = 3.3x106 Mpc3
• Number density of objects with M>10^11M : logΦMpc-3)= -5.2
• Halo:stellar mass ratio = 15
• Low redshift data from Caputi et al. (2006) study in GOODS (blue points)
• Approx ~ 1% of high-mass galaxies in place by z~5
Massive galaxies at z>5Comparison with halo mass function:
number density of massive galaxies in UDS fully consistent with available dark matter halos in concordance cosmology
• Thick solid line shows z=0 galaxy mass function from Cole et al. (2001)
• Dotted and stepped curves show predicted z=5.3 galaxy mass functions from Granato et al. (2004) and Bower et al. (2006) models.
• UDS number density is in good agreement with model predictions
Massive galaxies at z>5Comparison with galaxy mass function:
Good agreement with model predictions maintained even if LBG selection technique is missing ~50% of stellar mass (e.g. Stark et al. 2006)
MF at z=0 (Cole 2001)
Durham model (Bower 2006)
Trieste model (Granato 2004)
10 – 15 % of local massive galaxies in place before z~3
The assembling of 80% of massive galaxies occurs in the range 1 < z < 3
Local space density
MCDM > 5 1012 M
MCDM > 2 x 1012 M
∗M* > 1011 M
The most massive galaxiesThe most massive galaxies
GOODS (Caputi et al. 2006)
Cirasuolo et al. 2008, in prep
• Combination of UDS EDR+SXDS data places constraints on the high-mass end of
galaxy mass function in the redshift interval 5<z<6.
• Number density of M>10^11M galaxies is found to be : logΦMpc-3)= -5.2
• Number density is in good agreement with the latest predictions for both the halo and galaxy mass functions at z>5
Massive galaxies at z>5Conclusions:
Next stage of this study is to exploit the deeper UDS DR1 data-set to study the UV-selected luminosity
function at z>4.5
The Universe at z>5The Universe at z>5
Bouwens et al. 2006
UV selected galaxy luminosity function at high-redshift
Faint end of high-z LF well determined from deep HST fields Bouwens et al. (2007)
B-drops at z~4
V-drops at z~5i-drops at z~6
Iye et al. 2006
Vast majority are faint (z-band > 26) and therefore not massive systems M < 1010M
Vast majority are faint (z-band > 26) and therefore not massive systems M < 1010M