New Results from the Recent HST Surveys: COSMOS, GOODS, UDF

Plan of the talk:

Density-Morphology relation

Discovery of a post-starburst galaxy at z ~7

Photometric redshift estimates

Evolution of LF of galaxies to z~2

Narrow-band searches for high-z galaxies with Subaru

AIMS (COSMOS)

• evolution of galaxy morphology, SFR, merging, LF, correlation function as a function of LSS and redshift

• Assembly of galaxies, clusters and dark matter up to 1014 Msun scales

• Reconstruction of dark matter distribution up to z >1

AIMS (UDF)

• Search for galaxies out to re-ionization epoch

• Extend study of star formation rate in galaxies to z ~ 6

• Study rest-frame optical properties of galaxies to high redshifts

• Estimate the luminosity function of galaxies at z ~ 6

AIMS (GOODS)

• Study of the mass assembly rate and star formation in galaxies

• Explore rest-frame morphologies of galaxies and their evolution with redshift

• Provide multi-waveband data to address fundamental questions regarding the formation and evolution of galaxies

COSMOS: Morphology-Density RelationCOSMOS: Morphology-Density Relation

Bahram Mobasher

Capak, Mobasher, Ellis, Scoville, Sheth, Abraham, ApJL 2005

Motivation:

Role of environment in shaping Hubble sequence 0<z<1

Ingredients:

ACS morphologies (+ proxies from photo-z/spectra)

Photometric redshifts (for slices)

Density estimates ( gals. Mpc-2 , lensing ….)

Stellar masses (requires deeper K-band)

Progress/issues:

Auto/visual morphologies & photo-z tested in 3 x 3 inner field

Robustness of 2-D as a tracer of 3-D density is an issue

Morphology-Density Relation: Progress & IssuesMorphology-Density Relation: Progress & Issues

Evolution of the T-Evolution of the T- relation 0 < z < 1 relation 0 < z < 1

Environmental density plays key role in governing morphological mix: - Continued growth in high but delay for lower regions - Slower conversion of spirals to S0s with only Es at z > 1?

Smith et al 2004 (astro-ph/0403455)

fE/S0 fE/S0

Evolution of the T-Evolution of the T- relation ACS clusters relation ACS clusters

Holland et al 2004 (astro-ph/0408165)

Explores the high end in more detail via GTO cluster sample (N=7, E:S0) Illustrates the advantage of combining COSMOS with cluster datasets?

fE/S0

COSMOS

Morphological Catalog (Abraham, Sheth + RSE)Morphological Catalog (Abraham, Sheth + RSE)

Morph-cat (RGA):

-based on earlier MDS, HDF precepts to I(AB)=24

- Asymm, Conc, Gini-C,

- N ~ ?

Reality check (RSE/KS):

- visual catalog I(AB)=22.5 in inner 33 g+I zone

- typed according to precepts used in MDS, HDF, GOODS

- N~700

Extension to full area:

N(tot) ~ ?

COSMOS T=5 Sc(d)m IAB<22.5

COSMOS T=1 E/S0 IAB<22.5

What limit for automated morphologies?What limit for automated morphologies?

Robustness of “classic” parameters (A-C test):

I(AB)=22.5 (COSMOS) is broadly equivalent to I(AB)=24 (HDF)

But how reliable is a projected 2-D density?But how reliable is a projected 2-D density?

Measured in a photo-z slice

True spatial density

/

Fidelity of using will depend on photo-z z, error and <z> itself (Benson VIRGO simulations)

Results

• Density-morphology relation was already in place at z~1

• We see a steady increase in the fraction of elliptical galaxies with decreasing redshift from z=1.2 to present

• The strength of this trend depends on the local density

Merging Photo-z & Morph-cats in the inner regionMerging Photo-z & Morph-cats in the inner region

V-I

Photo-z

Independent demonstration of robustness of photo-z’s

Search for the highest redshift galaxies

B. Mobasher, M. Dickinson,

H. C. Ferguson, M. Giavalisco,

T. Wiklind, R. S. Ellis, M. Fall

N. Grogin, L. Moustakas, N. Panagia

D. Stark, M. Sossy, M. Stiavelli E. Bergeron, S. Casertano, A.

Koekemoer, M. Livio, C. Scaralata

Mobasher et al (2005) submitted

Hubble Ultra-Deep Field

A sub-area of the GOODS-S (CDF-S)

CS Area: 3’ x 3’

mAB (z850LP) = 28.4 mag

(10for extended source over 0.2 arcsec2 aperture)

NICMOS Area: 2.5’ x 2.5’

mAB(F160W) = 25.1 mag.

(10for extended source)

GOODS-South

HUDF is fully

covered By Spitzer

HUDF+GOODS-S

ACS: B435V606 i775 z850LP

NICMOS: J110 H160

ISAAC: Ks

Spitzer: IRAC (3.6-8.0 micron)

MIPS: 24 micron

Radio 1.4 GHz (ATCA, VLA)

X-ray (Chandra)

Ground-based UBVRIJHK images

Photometric Redshifts -10% accurate

High-z selection

Sources with (J – H)AB > 1.3 and no detection in optical-ACS bands were

selected.

Two sources were identified. One close to an X-ray source (likely an

AGN) while the other is not associated with any X-ray (or radio)

source- UDF033238.7-274839

Spectral Energy Distributions

Simultaneously optimizing model parameters consisting of redshift (z),

extinction (E(B-V)), starburst age (tsb) and metallicity (Z)

Population synthesis models:

STARBURST99 (Vazquez & Leitherer 2005)

Bruzual & Charlot 2003

Associated with an X-ray source

Model Parameters

Parameter range:

Redshift 0 < z < 12

Extinction 0 < E(B-V) < 1

Starburst age 0.1 < tsb < 5 Gyrs

Metallicity 0.004, 0.008, 0.02, 0.04

Calzetti extinction law

Salpeter IMF 0.1 < M < 100 Msun

Star formation laws

Continuous SF mode

Instantaneous SF- single SF burst follwed by a decrease for tsb yrs

Exponentially decreasing SFR with e-folding time scale

0,100,200,300,400 Myrs

Best SED Fits

STARBURST99

Instantaneous star formation burst

z=7.2; EB-V =0.05; tsb=600 Myrs Z=0.004

Bruzual & Charlot

Exponentially decreasing SFR with 0

z=7.0; E B-V =0.15; tsb=400 Myrs Z=0.008

Degeneracies

It is possible that different combinations of parameters could

Produce equally acceptable fits.

low metallicity SED and high age or extinction could mimic an SED with

higher metallicity and lower age/extinction

Every single combination of

age (0.1-5 Gyrs)

Metallicity (0.2-2.5 solar)

Extinction (0 < E(B-V) < 1)

Redshift (0 < z < 12)

e-folding SFR (0-500)

is considered

It is possible that the observed SED is caused by:

• Contribution from old stellar population at z ~ 2-4

• heavily obscured starburst at lower redshifts

• Complicated degeneracy between redshift, extinction, metallicity, age

• An old population SED was simulated by fixing the age to 1-2 Gyr and fitting the rest of the parameters- no acceptable fit to the observed SED (at the > 5 level) was found at any redshift.

• To fit the observed SED with a heavily reddened object, one needs E(B-V) > 0.5 and a MUCH reduced likelihood.

Spectroscopic Campaign

Keck vs. Gemini

Gemini vs. VLT

VLT vs. Keck

Keck NIR SpectrumR. S. Ellis & D. Stark

ResultsHigh stellar mass of 8 x 1010 Msun

Galaxy formed the bulk of its stars very rapidly, entering a significant

quiescent phaseFormed today’s of Milky way mass when the Universe was 200-400 Myr

old (z=12-20)Evidence for monolitic formation

of galaxies ?Its SED is different from LBGs

JWST target ?

GOODS

Photometric redshift measurement

Evolution of rest-frame galaxy LF to z ~ 2

Narrow-band survey and nature of LAEs at z = 5.7- their Spitzer

properties

GOODS Phot-z MeasurementMobasher et al 2004, 2005

• six templates used• Luminosity function used as prior• Cosmic opacity from Madau et al.• Extinction allowed as a free parameter,

estimating E(B-V) for each galaxy• Interpolates the spectral types• Easily extended to other bands (ie IRAC,

GALEX etc)

Input: Galaxy magnitudes, magnitude errors, templates, filter response

functions

Output: z(phot), spectral types, redshift probability distribution,

conventional and prior-based redshifts, extinction

COSMOS phot-z’s: UBVRizK bands, E, Sa, Sb, Sc, Im, Starburst templates

Luminosity functions are calculated using* 1/Vmax method* Maximum likelihood method

Traditionally (ideally): each galaxy has one redshift-> one absolute magnitude-> one galaxy added to magnitude bin in LF

Using phot-z's:Phot-z's have relatively large errorsEach galaxy is represented by a redshift distribution

Evolution of rest-frame LFs

T.Dahlen, B.Mobasher,R.Somerville, L.Moustakas, M.Dickinson, H.C. Ferguson, M.Giavalisco ApJ 2005

Combine 1100 arcmin2 optical (UBVRI)- (RAB < 24.5) and 130

arcmin2 near-IR (JHK)-

(KAB < 23.2) surveys

Advantages…

• Deep and wide area near-IR data allow study of rest-frame optical LF to z~2

• Near-IR data allow us to probe deeper in the rest-frame optical LFs in the range z~1-2

• Allows study of rest-frame J-band LF (mass function) to z=1

• Allow measurement of SFR to z~2.2, using rest-frame 2800A measurements- compare to GALEX

LF Results• The shape of the LFs vary significantly

between different spectral types.

• Early-type galaxy show a near gaussian LF

• Starburst LFs have steep faint-end slopes

Dimming of 0.6 mag in M*J

between z=0.1 and 1

Results- evolution of rest-frame LFs

• Evolution of rest-frame U, B & R-band LFs are considered in six equal comoving volumes to z~2

• M* brightens by 2.1 (U), 0.8 (B) and 0.7 (R) mag between z~0.1 and z~2. There is a strong decline in * with redshift in U-band

• Rest-frame J-band LF shows a dimming between z~0.4 and 0.9 mean stellar mass was lower in the past

• There is strong evolution with redshift in the relative contribution from different spec. types to the luminosity density

SFR from rest-frame 2800A Mobasher et al 2005

Structure and Evolution of Starburst Galaxies

Mobasher et al (2004)Aims:How different is the morphology of starburst and normal

galaxies ?How significant is the effect of galaxy interactions on SFR ?Sample selection:Sample of SB galaxies is selected based on their spectral

types (from SED fitting). A Control sample of normal (E,Sp) galaxies was also selected in the same way.

Rest-frame B-band morphologies were determined, using BViz band ACS images and photometric redshifts

Concentration

• Most z<=1 optically selected starbursts have concentration indices which are significantly smaller than most early types

• C>0.3 : 12 % SB, 18% Late, 73% E/Sa

• Komogorov-Smirnov ( K-S) test

- SB vs Early type : 7e-7 (> 99.9%)- SB vs Late-type : 0.53

• Large C & galfit Sersic n=3-4 correlate

AGN fraction : CDF-S X-ray catalog : 2% of SB host AGN vs >25% of Early types

Asymmetry in rest frame B

• 55 % of z<=1 optically selected starbursts have high AB (>0.3) compared to lower fractions in late (20% ) and early (12%).

• K-S test on AB

- SB vs Early type : 1e-10 - SB vs Late-type : 3e-4

AB

Large AB : highly asymmetric distribution of massive SF (no m=2 symmetry)

- Externally triggered : tidal interactions, mergers

Narrow-band search for high-z galaxies

• A survey in NB816 over the GOODS-ACS area

• NB816 < 25

• I – NB816 > 0.7

• Not detected in B and V-bands

• 29 sources identified over the GOODS area

Rest-frame Properties of LAEsMobasher, Taniguchi, Ajiki 2005• 75% of narrow-band selected LAEs have

spect. Confirmation at z =5.7 (Rhoads et al 2003)

• No Spect. Data is yet available for our sample (BIG ASSUMPTION!)

• 18 (>60%) of the LAEs detected by IRAC

Sersic n dist. in rest-frame UV

rest-optical & -IR at z=5.8

• SST IRAC detections of z~6 galaxies=> stellar population & dust fitting possible

Dickinson et al in prep

ch1, 3.6mrest=5300A

ch2, 4.5mrest=6600A

SFR vs. Mass

Nature of LAEs

• Dominated by disk systems• Varied morphological types• SFR ~ 20 – 40 M(sun)/yr (estimated from

Ha line)• How is the LAEs SEDs compared to that of

the LBGs ?• ACS (iz) ISAAC (JHK) IRAC data

available