High Redshift Starbursts

High Redshift Starbursts

Mauro GiavaliscoSpace Telescope Science Institute

and the GOODS team

STScI/ESO/ST-ECF/JPL/SSC/Gemini/Boston U./U. Ariz./U. Fla./U. Hawai/UCLA/UCSC/IAP/Saclay/Yale/AUI

GOODS: Great Observatories Origins Deep Survey

The Quest for the Early Galaxies

During the mid-90’s, with improved instrumentation, the commissioning of the 8-m class telescopes, and the repair of HST, a number of influential deep galaxy surveys (CFRS, LBGS, HDF) uncovered two important pieces of evidence:

1. Normal, luminous galaxies (the bright end of the Hubble sequence) were essentially in place by z~1 Massive (M*) galaxies formed prior to z~1

2. The universe was well populated with star-forming galaxies at z~3 At z~1 these must be old and/or massive or both. Are these the progenitors of the

bright galaxies?

Earlier suggestions that the bulk of galaxies formation occurred at z<1 and that “essentially no galaxies are to be expected at redshifts z>1” (1993, actual quote) were dismissed.

Giavalisco 2002 ARA&AEllis 1997 ARA&A


Abraham et al. 1996

Lilly et al. 1995


Star-forming galaxies at z~3 (Lyman Break Galaxiess)

Steidel, Giavalisco, Dickinson, Pettini & Adelberger 1996


Efficient star formation at z>2.5

Steidel, Adelberger, Giavalisco, Dickinson & Pettini 1999


Galaxy morphology at z~3

Giavalisco et al. 1994; Giavalisco et al. 1996;Steidel, Giavalisco, Dickinson & Adelberger 1996;Lowenthal et al. 1997; Dickinson 1998; Giavalisco 1998;Papovich, Giavalisco, Dickinson, Conselice & Ferguson 2003Papovich, Dickinson, Giavalisco, Conselice & Ferguson 2004

•Smaller•Regulars,•Irregulars,•Merging,•Spheroids?•Disks?•No Hubble Seq.•No -dependence


UV-star formation rates

Some rates are relatively low, ~ today’s spirals;

others are prodigiously high

Metallicity ~1/10 to ~ solar

Still an open issue


The birth of the GOODS

• No Hubble Sequence apparently observed at z>2. When and how did it form?

• What kind of galaxies are LBGs– Bursting dwarfs? Massive? – What did they evolve into? How much stellar mass did

they contribute?– Up to which redshift are there LBGs? When did SF on

galactic scale start?

• Are there other (non LBG selectable, I.e. non star-forming or very obscured) galaxies at z>2?

• How does star formation occur and evolve?


The GOODS Treasury/Legacy Mission

Aim: to establish deep reference fields with public data sets from X-ray through radio wavelengths for the study of galaxy and AGN evolution of the broadest accessible range of redshift and cosmic time.

GOODS unites the deepest survey data from NASA’s Great Observatories (HST, Chandra, SIRTF), ESA’s XMM-Newton, and the great ground-based observatories.

Primary science goals:• The star formation and mass assembly history of galaxies• The growth distribution of dark matter structures • Supernovae at high redshifts and the cosmic expansion• Census of energetic output from star formation and supermassive black holes• Measurements or limits on the discrete source component of the EBL

Raw data public upon acquisition; reduced data released as soon as possible


A Synopsis of GOODS

GOODS Space• HST Treasury (PI: M. Giavalisco)

– B, V, i, z (3, 2.5, 2.5, 5 orbits)– 400 orbits

– Δθ = 0.05 arcsec, or ~0.3 kpc at 0.5<z<5– 0.1 sq.degree– 45 days cadence for Type Ie Sne at z~1

• SIRTF Legacy (PI: M. Dickinson)– 3.6, 4.5, 5.8, 8, 24 μm– 576 hr– 0.1 sq.degree

• Chandra (archival):– 0.5 to 8 KeV– Δθ < 1 arcsec on axis

• XMM-Newton (archival)

GOODS Ground• ESO, institutional partner (PI C. Cesarsky),

CDF-S– Full spectroscopic coverage in CDF-S

– Ancillary optical and near-IR imaging

• Keck, access through GOODS’ CoIs– Deep spectroscopic coverage

• Subaru, access through GOODS’ CoI– Large-area BVRI imaging

• NOAO support to Legacy & Treasury– Very deep U-band imaging

• Gemini– Optical spectroscopy, HDF-N

– Near-IR spectroscopy, HDF-S

• ATCA, ultra deep (5-10 Jy) 3-20 cm imaging, of CDF-S

• VLA, ultra deep HDF-N (+Merlin, WSRT)

• JCMT + SCUBA sub-mm maps of HDF-N


GOODS/ACS

B = 27.5

V = 27.9

i = 27.0

z = 26.7

∆m ~ 0.3-0.6

AB mag; S/N=10Diffuse source, 0.5” diameterAdd ~ 0.9 mag for stellar sources

HDF/WFPC2

B = 27.9

V = 28.2

I = 27.6

In ~2-3 months we will release a new stack of ~15 orbits in the z band, as well as ~50% and ~30% more exp. time in the i and V bands, in both fields, plus source catalogs (GOODS++)


GOODS galaxies at High Redshift

•Theory predicts that dark matter structures form at z~20-30

•It does not clearly predict galaxies, because we do not fully understand star formation

•Empirical information on galaxy evolution needed to the highest redshifts

•GOODS yielded the deepest and largest quality samples of LBGs at z~4 to ~6

B435 V606 z850

Unattenuated Spectrum Spectrum

Attenuated by IGM

B435 V606 i775 z850

z~4


LBG color selection

B-dropouts, z~4 V-dropouts, z~5


Galaxies at z~6 (~6.8% of the cosmic age)

S123 #5144: m(z) = 25.3

ACS/grism, Keck/LRIS & VLT/FORS2 observations confirm z=5.83

Dickinson et al. 2003


Observed redshift distribution

V

Z=5.78

Z=5.83

Z=6.24?

Spectra fromBunker et al. 2003;Stanway et al. 2003;Vanzella et al. 2004and the GOODS Team

Curves from fullnumerical simulationsGiavalisco et al. 2004, 2005

#24


LBG luminosity function

Apparently, very little evolution in the UV luminosity function


The history of the cosmic star formation activity:

We find that at z~6 the cosmic star formation activity was nearly as vigorous as it was at its peak, between z~2 and z~3.

NOTE: soon, nearly all GOODS will have three times the original exposure time in z band, and ~50% more in i band (thanks to the Sne program). Measure at z~6 will significantly improve.

Giavalisco et al. 2004Giavalisco et al. 2005, in prep.

=-1.6 assumed


Still uncertainty on measures

Bouwens et al. 2004

•LF still not well constrained •Clean z~6 color selection still missing•Cosmic variance still not understood

•Will use SST data to refine z~6 sample•Will triple exp time in GOODS

See also Bunker et al. 2004


SFR from X-ray emission

Lehmert et al 2005See also Giavalisco 2002, ARA&A


Star formation rates

Dust obscuration correction:

Calzetti starburst obscurationlaw

B&C synthetic SED

Similar to what observed at z~3

z~4 B-band dropouts


SIRTF Imaging

GOODS sensitivity

0.1126.3

0.2125.6

1.3523.6

1.6623.4

20.020.7

5-σ limiting flux μJy5-σ limiting AB mag


Stellar mass & star formation

PAH + continuum (24 m)

UV

Far IR(GTO)

Optical+ near-IR+ nebular lines

Mass: Rest-frame near-IR (e.g., rest-frame K-band at z~3), provides best photometric measure of total stellar content Reduces range of M/L() for different stellar populations Minimizes effects of dust obscuration

Star formation: Use many independent indicators for to calibrate star formation (obscured & open) in “ordinary” starbursts (e.g. LBGs) at z > 2.• mid- to far-IR (SIRTF/MIPS); rest-frame UV (e.g, U-band); radio (VLA, ATCA); sub-mm (SCUBA, SEST); nebular lines (spectroscopy)

Stellar mass fitting

Measuring star formation


Rest-optical & -IR at z~6

• 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


Luminosity Density versus Color and Redshift

increase of ~33%

U- and B- dropouts have similar UV-Optical color-magnitude "trends”.

Rest-frame UV luminosity density roughly comparable at z ~ 3 and 4.

Increase of ~33% in the rest-frame B-band luminosity density from z ~ 4 to 3.

UV-Optical color reddens from z ~ 4 to 3, which implies an increase in the stellar-mass/light ratio.

Suggests that the stellar mass is increasing by > 33% growth in B-band luminosity density.

Papovich et al. 2003


Implications for Galaxy Evolution

Dickinson, Papovich, Ferguson, & Budavari 2003


Implications for Galaxy Evolution

Dickinson, Papovich, Ferguson, & Budavari 2003

GOODS; Papovich et al. 2004

Stellar mass is building up

We still need to know how this growth depends on the total mass

Total mass of individualgalaxies seems to evolveless rapidly:bottles form first, wine is added later


Morphology of Lyman Break Galaxies at z~4

Sersic profile fits and Sersic indices:

[Ravindranath et al. 2005]

Irregulars: (n < 0.5)

Disks: (0.5 > n > 1.0)


Morphology of Lyman Break Galaxies at z~4

Bulges (n > 3.0)

Central compact component / point sources? (n = 5.0)


LBG morphology: light profiles

Ravindranath et al. 2005

We measured the light profiles and parametrized them with the Sersic index


Morphology of LBG

Theory predicts that when they form undisturbed, galaxies are disks.Images show a distribution of morphology. Both spheroid-like and disk-like morphology areobserved.

Ravindranath et al. 2005z=0 disksz=0 spheroids


Morphology of LBG: the GINI and M20 coefficients

Lotz, Madau, Giavalisco, Conselice & Ferguson 2005

Both spheroids and disk, as well as “transitional morphologies, observed.Major mergers estimated at 15-25%, both at z~4 and z~1.4 (in agreement with kinematics of close pairs with DEIMOS-DEEP –Lin et al. 2005)

mergers spheroids


Local galaxies at high redshift

Statistics calibrated using local galaxies

Lotz et al. 2005


LBG morphology

Lotz et al. 2005


Infrequent “morphological k-correction”

Dickinson 1998

Papovich, Giavalisco, Dickinson, Conselice & Ferguson 2004

Papovich, Dickinson, GiavaliscoConselice & Ferguson 2004

WFPC2 (HDF) and NIC3 J and H images

Internal color dispersion consistent with relatively young and homogeneous stellar population


The Evolution of galaxy size

Standard ruler

R~H(z)-2/3

R~H(z)-1

First measures at these redshiftsTesting key tenets of the theory

Galaxies appear to grow hierarchically

Ferguson et al. 2003


Galaxy Clustering at High Redshift

• Galaxies at high redshifts have “strong” spatial clustering, I.e. they are more clustered than the z~0 halos “de-evolved back” at their redshift.– High-redshift galaxies are biased, I.e. they occupy only the most

massive portion of the mass spectrum (today, the bias of the mix is b~1).

• Important: – evolution of clustering with redshift contains information on how

the mass spectrum gets populated with galaxies as the cosmic time goes on.

– Clustering of star-forming galaxies contains information on relationship between mass and star formation activity


Clustering of star-forming galaxies at z~3

Giavalisco et al. 1998Steidel et al. 2003Adelberger et al. 1998

r0=3.3+/- 0.3 Mpc h-1

= -1.8 +/- 0.15


Strong clustering, massive halos

Porciani & Giavalisco 2002 Adelberger et al. 2004

=1.55r0 =3.6 Mpc h-1


local galaxiesm*>2.5E10 MO

m*>1.0E11 MO

EROs

sub-mm

K20

SDSS QSOs

LBGs

Somerville 2004


Clustering segregationmass drives LUV (SFR)

Adelberger et al. (1998, 2004)Giavalisco et al. (1998)Giavalisco & Dickinson (2001)

GOODS Ground

Lee et al. 2005


Clustering segregation at z~4 and 5

Lee et al. 2005

Clustering segregation is detected In the GOODS ACS sample at z~4

Consistent with other measures, e.g.Ouchi et al. 2004


Halo sub-structure at z~4

Lee et al. 2005

We are observingthe structure withinthe halo.

Break observed at ~10 arcsec

Note: 10 arcsec at z~4 is about ~350 kpc.

See also Hamana et al. 2004


The Halo Occupation Distribution at z~4

<Ng>=(M/M1)

M>Mmin

Lee et al. 2005

Consistent with Hamana et al. 2004and Bullock et al. 2001

2-1-


The Halo Occupation Distribution at z~0

From SDSS dataZehavi et al. 2004

= 0.89 +/- 0.05M1 = (4.74 +/- 0.50) x 1013 MO

Mmin = 6.10 x 1012 MO


Halos and Galaxies at z~3-5

Lee et al. 2005

Halo substructure:we observe an excess of faintgalaxies around bright ones.massive halos contain morethan one LBG

“Bright Centers”: z_850<24.0“Faint centers”: 24.0< z_850 <24.7“Satellites”: z_850 >25.0


Halos and Galaxies at z~3-5

Clustering scaling in good agreement with hierarchical theory

Implied halo mass in the range5x1010 – 1012 MO

1-σ scatter between mass and SFRsmaller that 100%

Giavalisco & Dickinson 2001Porciani & Giavalisco 2002Lee et al. 2004, in prep.


EROs, orUV-faint galaxies at z~2-3

Galaxies selected from near-IR photometry [(J-K)>2.3]

A fraction would NOT be selected by LBG criteria (UV selection)

However, overlap with LBG not quantifiedand likely significant (see Adelberger et al. 2004).

They appear in general more evolved, I.e.more massive (larger clustering), with larger stellar mass, more metal rich, and more dust obscured) than LBGs. Occurrence of AGN also seems higher.

At z~3 these galaxies have about50% of the volume density of LBGs (highly uncertaint). However; they possibly contribute about up to 100% of the LBG stellar mass density, becausethey have higher M/L ratios Van Dokkum et al. 2004


EROs

Ks< 22, R-Ks>3.35

Moustakas et al. 2004


EROs

•ACS resolution is crucial tounderstand the nature of EROs•Broad-band SED or statistical morphology cannot discriminate•Evidence of massive galaxies at z~1.2-1.5

Moustakas et al. 2004


HUDF/GOODS EROs

Yan et al. 2004


HUDF/GOODS EROs

Yan et al. 2004

Uses HUDF plus GOODS-SST data

SED fitting disfavour very dustobscured, star-forming galaxies

SED better reproduced by a two-component composite populations: an old, evolved one, plus a low-intensity star-forming one.Stellar mass relatively large:1010 – 1011 MO

Evidence that similar objects exist at z~7 (Mobasher et al. 2005)


LBGs at z~5 and 6

Yan et al. 2005

Evidence of large stellar mass at z~5, 6


LBGs at z~5 and 6

Yan et al. 2005

Evidence of large stellar massat z~5, 6


An evolved, massive galaxy at z~7?

Mobasher et al. 2005, submitted to Nature

HUDF + GOODS-SST


NIR-selected galaxies

NIR selected galaxies with K<20 VLT FORS spectra

SED fits show Mstar >1011 MO

Claims that NIR selection yields more massive galaxies than UV selection

Daddi et al. 2004


Different populations?

Adelberger et al. 2004

Near-IR selectionpicks up the high-endof the distribution of masses (total and stellar)


Galaxies at z~1-0

Evolution of the integrated mass density, M>1011 MO

GOODS data

Little evolution in the stellar mass density from z~1 to today

Note that at z~1 spirals dominatedstellar mass density; the oppositeat z~0: morphology transformation

Bundy, Ellis & Conselice 2005

Cosmic variance

Today’s stellar mass density

Ravindranath et al. 2003

–Sersic indices n<2–Rest-frame MB <-19.5–Photometric redshifts


Disk galaxy evolution from GOODSRavindranath et al. 2003

Tendency for smaller sizes at z~1 (30% smaller)

Number-densities are

relatively constant to z~1


The evolutionary link?

Giavalisco, 2002 ARA&A

The expected evolution of clustering (correlation length) suggests what thehigh redshift galaxies might evolve into at later epochs.

Adelberger et al. 2004


Summary

• GOODS exploring fundamental issues of cosmic origins• Large-scale star formation in place at less than ~7% of the cosmic time:

– SF galaxies observed to at least up z~7– Massive galaxy started very early in the cosmic evolution

• Cosmic star formation (as traced by UV light) varies mildly at 3<z<6– Universe is ~ as prolific a star former at z~6 as it is at z~3, after triplicating age– Unclear proportion of obscured and evolved galaxies– Obscured SF might contribute up to 100% of stellar mass density and star formation (2x)

• SF galaxies seem already diversified at z~4. “Evolved” galaxies up to z~7?– Morphology mix includes spheroids, disks; 14-25% mergers at z~1.4-5

• Direct evidence of growth of stellar mass from z~4 to z~1.• Galaxies get smaller at z>1; size evolution consistent with hierarchical growth• Massive galaxies in place at z~1; some galaxies are massive at z~2-3• Spatial clustering key to study relationship of star formation and dark matter:

– Evidence of halo sub-structure at z~4. Transition at r~1 Mpc; Mmin~109 MO

– Spatial clustering depends on UV luminosity, decreases for fainter galaxies– More massive halos host more star formation; scaling consistent with CDM spectrum– Implies relatively large total masses: 5x1010 – 1012 MO

High Redshift Starbursts

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