the irac/mips survey in egs

The IRAC/MIPS Survey in EGS

Jia-Sheng Huang /Giovanni Fazioand the EGS Consortium

Harvard-Smithsonian Center for AstrophysicsCambridge, MA 02138, USA

Extended Groth Strip Extended Groth Strip (EGS)(EGS)

Spitzer observation of Spitzer observation of EGSEGS

IRAC(3.6, 4.5, 5.8, 8.0um): Jan. 2004 IRAC(3.6, 4.5, 5.8, 8.0um): Jan. 2004 (1.5h/p) , July 2004 (1.5h/p), total (1.5h/p) , July 2004 (1.5h/p), total ~120h for all IRAC observation (3h/p). ~120h for all IRAC observation (3h/p).

MIPS(24, 70, and 160um): Jan. 2004 MIPS(24, 70, and 160um): Jan. 2004 Spitzer safed, only 1/3 data were taken; Spitzer safed, only 1/3 data were taken; June 2004, full depth data; total ~50-60h June 2004, full depth data; total ~50-60h for MIPS observation.for MIPS observation.

Mosaic image: 3.6, 4.5, 5.8, 8.0, 24, 70umMosaic image: 3.6, 4.5, 5.8, 8.0, 24, 70um Catalogs: 8um, 24um, 70um-selected Catalogs: 8um, 24um, 70um-selected

samples.samples.

Extended Groth Strip Extended Groth Strip (EGS)(EGS)

IRAC 3.6 µm IRAC 8.0 µm

5’x5’ 3h

Q1700 deep fieldQ1700 deep field

IRAC 3.6 µm IRAC 8.0 µm

5’x5’ 8h

NOISE NOISE AS A FUNCTION OF TIMEAS A FUNCTION OF TIME

(Q1700 FIELD)(Q1700 FIELD)

Noise in Channels Noise in Channels 1 and 2 deviates 1 and 2 deviates from root time at from root time at ~ 3000 sec (onset ~ 3000 sec (onset of source of source confusion noise).confusion noise).

Noise in Channel Noise in Channel 3 and 4 is still 3 and 4 is still decreasing as root decreasing as root time at 20,000 time at 20,000 sec.sec.

EGSEGS

Number Counts at 3.6 Number Counts at 3.6 micronmicron

Mid-IR Properties of Mid-IR Properties of Normal Galaxies at z<1.5Normal Galaxies at z<1.5 DEEP redshift sample (>10k DEEP redshift sample (>10k

galaxies with z)galaxies with z) B, R, I photometryB, R, I photometry High resolution 2d-spectrum (Keck High resolution 2d-spectrum (Keck

DEMOS)DEMOS) z<1.4z<1.4

Galaxies: Blue vs RedGalaxies: Blue vs Red

MIR Spectroscopy with MIR Spectroscopy with IRAC IRAC

Really?Really?

UV-IR SED for Blue UV-IR SED for Blue Galaxies Galaxies

0.8<z<1.2

0<z<0.5

IR Color Evolution??IR Color Evolution??

8um Selected Sample8um Selected Sample

8um selected sample8um selected sample

DEEP2+BM/BX+LBGDEEP2+BM/BX+LBG

8 micron Number Counts 8 micron Number Counts for each redshift bin for each redshift bin

SEDs of the MIPS 24 SEDs of the MIPS 24 micron Galaxiesmicron Galaxies

Morphologies of the Morphologies of the 24um Source by J. Lotz 24um Source by J. Lotz

et alet al Using GINI-M50 Merger Using GINI-M50 Merger

Classification to classify all 24um Classification to classify all 24um sources at z<1.2sources at z<1.2

50% Late type Spiral, 25% Early 50% Late type Spiral, 25% Early Type Spiral, 5% E/S0, 15% MergersType Spiral, 5% E/S0, 15% Mergers

13 ULIRGS, half of them are 13 ULIRGS, half of them are mergers.mergers.

IR properties of Galaxy IR properties of Galaxy Pairs in EGSPairs in EGS

SCUBA Sources in EGSSCUBA Sources in EGS

SMG SEDSMG SED

SCUBA sources detected SCUBA sources detected in the 24um bandin the 24um band

SCUBA sources detected SCUBA sources detected in the 70um bandin the 70um band

Radio Sources in EGSRadio Sources in EGS

VLA 6 cm covering the whole stripVLA 6 cm covering the whole strip 48 sources detected at f>0.5 mJy. 34 48 sources detected at f>0.5 mJy. 34

are single souces, the rest are either are single souces, the rest are either double or confused.double or confused.

Out of 34, 28 are detected in the Out of 34, 28 are detected in the IRAC Bands, the remaining 6 have IRAC Bands, the remaining 6 have no IRAC counterparts.no IRAC counterparts.

X-ray Sources in EGSX-ray Sources in EGS

ConclusionConclusion IRAC colors can characterize galaxy spectra IRAC colors can characterize galaxy spectra

type (blue/red) at z<1.5type (blue/red) at z<1.5 IRAC colors is a good redshift indicator.IRAC colors is a good redshift indicator. The 8 micron and 24 micron selected samples The 8 micron and 24 micron selected samples

in EGS have significant number of galaxies at in EGS have significant number of galaxies at z>2z>2

The MIR band SEDs show that radio and The MIR band SEDs show that radio and SCUBA galaxies are either starburst or AGN SCUBA galaxies are either starburst or AGN at z>1at z>1

The Chandra sources have a much wider IRAC The Chandra sources have a much wider IRAC color distribution than those just with power-color distribution than those just with power-law SEDs.law SEDs.

LBG SEDLBG SED

LBG Luminosity FunctionLBG Luminosity Function

QSO SEDsQSO SEDs

We are still working on We are still working on 3.6/4.5 Catalogs3.6/4.5 Catalogs

Want to see more Want to see more exciting stuff?exciting stuff?

Join Our Panel Join Our Panel Discussion!!!Discussion!!!

K-Band Selected Sample in EGS

Photometric Redshift Photometric Redshift AccuracyAccuracy

GALAXY MASS FUNCTIONS ( 0.2 < z < 1.4)

(Preliminary Results; K. Bundy et al. (Caltech))

Sample is limited to K < 22.8 (AB) and R < 21.4 (AB)

Number of galaxies in three redshift bins is: 459, 444, 659.

Poisson errors smaller than plot symbol.

Drop off at low mass due to incompletemess.

Incompletemess at high mass end will improve with increased sample volume.

0.2 < z < 0.51

0.51 < z < 0.8

0.8 < z < 1.4

Log M

Log

dN

/dM

GALAXY MASS FUNCTIONS ( 0.2 < z < 1.4)GALAXY MASS FUNCTIONS ( 0.2 < z < 1.4)(Preliminary Results)(Preliminary Results)

First mass functions based on rest frame K-band First mass functions based on rest frame K-band luminositiesluminosities Have higher accuracy.Have higher accuracy. Dust effects mitigated.Dust effects mitigated.

Mass functions agree with previous results based Mass functions agree with previous results based on K-band observations.on K-band observations.

Little evolution exists in the shape of the mass Little evolution exists in the shape of the mass function over these redshifts.function over these redshifts.

Semi-analytic models are in broad agreement with Semi-analytic models are in broad agreement with these observations.these observations.

Z=2Z=2

SCUBA Sources in the SCUBA Sources in the Lockman Hole AreaLockman Hole Area

IRAC Imaging of Distant Red Galaxies (z > 2)

in HDFS

• FOV = 5 arcmin2

• Deep imaging • UBVI (HST/WFPC2)• Js, H, Ks (VLT/ISAAC); Ks < 22.5 • 3.6, 4.5, 5.8, 8.0 micron (Spitzer/IRAC)

• Deepest Ks band image used to resolve galaxies; confusion not issue

HDFS: WFPC2 I + ISAAC Js,Ks

Typical Properties DRG (JsKs > 2.3) Galaxies

Redshift z = 2.6 ± 0.5Number density 0.0014 ± 0.0004 h3/Mpc3 (40% of LBGs)

Ages 1 2 GyrAv 1 2.5 mag

SFR 15 150 Msolar/yr Stellar Masses 1011 Msolar

*SED modeling: Bruzual Charlot 03 models, Salpeter IMF, Calzetti 2000 dust law

Lyman break GalaxiesJsKs galaxies

single burstconstant SF + Av=1.5

Lyman break GalaxiesJsKs galaxies

single burstconstant SF + Av=1.5

LGBs

Js - Ks > 2.3

Single Burst SF

70% constant SF + dust 30% single burst

IRAC Imaging of JsKs > 2.3 Galaxies in HDFS

• Galaxies are massive (1011) and evolved (high M/LK) May dominate stellar mass density at z ~ 23

• Have high surface density (~ 3 arcmin2 to K = 22.5).

• Space densities about one-half LGBs.

• IRAC distinguishes between dusty star forming galaxies (70%) and maximally old ``dead’’ galaxies (30%).

Z=3Z=3

Lyman-Break Galaxies Lyman-Break Galaxies (LBGs)(LBGs)z ~ 3z ~ 3

Redshift ~3 galaxies selected by UV-Redshift ~3 galaxies selected by UV-dropout technique (Steidel et al.)dropout technique (Steidel et al.)

Optical observations sample the rest-frame Optical observations sample the rest-frame UV: are these really massive galaxies or UV: are these really massive galaxies or just extreme star-formers?just extreme star-formers?

IRAC bands sample the rest-frame near-IR: IRAC bands sample the rest-frame near-IR: less affected by extinction, dominated by less affected by extinction, dominated by old, lower-mass stars old, lower-mass stars galaxy stellar mass galaxy stellar mass

LBGs in Q1700 FieldLBGs in Q1700 FieldP. Barmby et al. 2004P. Barmby et al. 2004

Field around z=2.7 Field around z=2.7 QSO, chosen for high QSO, chosen for high ecliptic latitude.ecliptic latitude.

Deep optical imaging Deep optical imaging allowed selection of allowed selection of few hundred LBGs.few hundred LBGs.

Portion of field has Portion of field has deep K-band data. deep K-band data.

~20 LBG candidates ~20 LBG candidates have spectra.have spectra.

3.6

4.5

5.8

8.0

LBGs: IRAC DetectionsLBGs: IRAC Detections

Most LBGs detected at 3.6, 4.5 Most LBGs detected at 3.6, 4.5 mm

About half detected at 5.8, 8.0 About half detected at 5.8, 8.0 m: m: SEDs are fairly flat, sensitivity is SEDs are fairly flat, sensitivity is lower at longer wavelengthslower at longer wavelengths

LBGs: SED Model LBGs: SED Model FittingFitting

Solar-metallicity, Solar-metallicity, Salpeter IMF models Salpeter IMF models from B&C 2003from B&C 2003

range of ages, star range of ages, star formation timescale, formation timescale, E(B-V), mass E(B-V), mass normalizationnormalization

massive stellar systems massive stellar systems with recent star with recent star formation:formation: MM**=1.5-4 x 10=1.5-4 x 1010 10 MMsunsun)) SFR = 7-33SFR = 7-33 MMsunsun/yr/yr Age: 100-300 MyrAge: 100-300 Myr

G R K 3.6 4.5 5.8 8.0

Galaxies at z =3Galaxies at z =3LGB Galaxies in EGSLGB Galaxies in EGS

J. Huang et al.J. Huang et al.

Among 334 LBGs in the EGS area, 193 Among 334 LBGs in the EGS area, 193 with spectroscopic redshifts (Steidel et with spectroscopic redshifts (Steidel et al 2003).al 2003).

244 are in the Spitzer EGS field.244 are in the Spitzer EGS field. ~200 are detected in the 3.6/4.5um ~200 are detected in the 3.6/4.5um

band.band. ~50 are detected in the 5.8/8.0um band.~50 are detected in the 5.8/8.0um band. 6 are detected in the 24um band.6 are detected in the 24um band.

R 3.6 4.5 5.8 8.0 24

LBG Colors in IRAC LBG Colors in IRAC bandsbands

z = 6

z = 4

z = 2

z = 3

SbcEM82

LBG Stellar Mass LBG Stellar Mass FunctionFunction

AGN SEDAGN SED

LBG StackingLBG Stacking

LGB with z

LGB total

LBGs: SummaryLBGs: Summary Easily detectable in deep IRAC observations. Easily detectable in deep IRAC observations. SEDs SEDs massive (M massive (M**>1.5-4 x 10>1.5-4 x 1010 10 MMsunsun),), star-star-

forming (10-150forming (10-150 MMsunsun/yr) galaxies./yr) galaxies. We probably see dust extinction in most We probably see dust extinction in most

LBGs.LBGs. The 8um/24um bright LBGs may beThe 8um/24um bright LBGs may be dusty, massive and be able to bridge LBGs dusty, massive and be able to bridge LBGs

and SCUBA sources.and SCUBA sources. The stellar mass function for LBG and The stellar mass function for LBG and

number of massive LBG are much higher then number of massive LBG are much higher then the SAM predicts. the SAM predicts.

Search for Diffuse Matter Search for Diffuse Matter in Halos of Edge-On in Halos of Edge-On

GalaxiesGalaxies Image of perfectly edge-Image of perfectly edge-

on galaxy NGC 891 at on galaxy NGC 891 at 3.6 microns.3.6 microns.

Evidence for extended Evidence for extended luminosity perpendicular luminosity perpendicular to the disk out to ~ 7 to the disk out to ~ 7 kpc, plus low contrast kpc, plus low contrast filaments.filaments.

Evidence for a thick disk Evidence for a thick disk of low mass stars.of low mass stars.

Similar results for NGC Similar results for NGC 59075907

NGC 891

Matt Ashby et al. (CfA)

Spitzer/IRAC Observationsof NGC 5907 from 3 - 10 m

N

• Observed a full 20x20 arcmin field with 10 x 100s HDR dithered exposures plus 3 flanking fields

10 kpc

• Every exposure at different dither

GALFIT ModelingGALFIT Modeling

IR emission modeled using GALFIT (Peng etal 2002) as IR emission modeled using GALFIT (Peng etal 2002) as discrete componentsdiscrete components

IRAC 3.6 um

Model: disk+bulge+sky+halo

Halo ResidualHalo Residual

Removing disk+bulge Removing disk+bulge components leaves components leaves substantial residual substantial residual

Surface brightness 21-24 Surface brightness 21-24 mag/arcsecmag/arcsec22

Axis ratio ~ 0.24Axis ratio ~ 0.24 Scale length ~ 130 arcsec; Scale length ~ 130 arcsec;

implies 2 kpc scale heightimplies 2 kpc scale height mm[3.6][3.6] = 16.1 = 16.1 Colors suggest excess is Colors suggest excess is

composed of very red stars.composed of very red stars. No evidence for a halo to a No evidence for a halo to a

surface brightness of 25.5 surface brightness of 25.5 mag/arcsecmag/arcsec22..

Image - (disk + bulge + sky)

IRAC 3.6 umN

SummarySummary For the first time IRAC’s wide-field surveys have For the first time IRAC’s wide-field surveys have

permitted the determination of the rest frame permitted the determination of the rest frame optical/near-IR luminosity functions and mass optical/near-IR luminosity functions and mass functions for galaxies at high z.functions for galaxies at high z.

• DRGs have been detected that are massive (10DRGs have been detected that are massive (1011 11 M Msunsun)) and and

evolved (high M/Levolved (high M/LKK) and may dominate stellar mass density at ) and may dominate stellar mass density at

z ~ 2z ~ 23.3. IRAC has detected a thick disk of very red IRAC has detected a thick disk of very red

objects around two edge-on galaxies.objects around two edge-on galaxies. Lots more to come!Lots more to come!

the irac/mips survey in egs

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