Exploring massive galaxy evolution with the UKIDSS Ultra-deep Survey Ross McLure, Michele Cirasuolo,...

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…


Cosmology


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

=


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

=


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



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






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


Comparison with theoretical models

Bower 2006

De Lucia 2007

Monaco 2007

Menci 2006

Nagamine 2006


next data-release will push one magnitude deeper






>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:


UDS has been observed by SCUBA at 850μm and AzTEC at 1.1mm as part of SHADES Survey


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






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


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


43

B-drops at z~4

V-drops at z~5

i-drops at z~6

Adapted from Bouwens et al. (2007)


44

Small area of HST fields means there is virtually no informationbrighter than M*


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



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)


How do we compare with previous studies?


Excellent agreement with Bouwens et al. (2007)

Surprising given: greatly differing areas, data & techniques


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


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


+


+

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)



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



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


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.


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



• 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

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Exploring massive galaxy evolution with the UKIDSS Ultra-deep Survey Ross McLure, Michele Cirasuolo,...

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