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High Redshift Starbursts. Mauro Giavalisco Space 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. The Quest for the Early Galaxies. Giavalisco 2002 ARA&A Ellis 1997 ARA&A.

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High redshift starbursts

High Redshift Starbursts

Mauro Giavalisco

Space 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

The quest for the early galaxies
The Quest for the Early Galaxies

Giavalisco 2002 ARA&A

Ellis 1997 ARA&A

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:

  • 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

  • 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.

Lilly et al. 1995

Abraham et al. 1996

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

Steidel, Giavalisco, Dickinson, Pettini & Adelberger 1996

Efficient star formation at z 2 5
Efficient star formation at z>2.5

Steidel, Adelberger, Giavalisco, Dickinson & Pettini 1999

Galaxy morphology at z 3
Galaxy morphology at z~3

  • Smaller

  • Regulars,

  • Irregulars,

  • Merging,

  • Spheroids?

  • Disks?

  • No Hubble Seq.

  • No l-dependence

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 2003

Papovich, Dickinson, Giavalisco, Conselice & Ferguson 2004

Uv star formation rates
UV-star formation rates

Some rates are relatively

low, ~ today’s spirals;

others are prodigiously


Metallicity ~1/10 to ~ solar

Still an open issue

The birth of the goods
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
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


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


Optical spectroscopy, HDF-N

Near-IR spectroscopy, HDF-S

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

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

JCMT + SCUBA sub-mm maps of HDF-N

A Synopsis of GOODS


B = 27.5

V = 27.9

i = 27.0

z = 26.7


B = 27.9

V = 28.2

I = 27.6

∆m ~ 0.3-0.6

AB mag; S/N=10

Diffuse source, 0.5” diameter

Add ~ 0.9 mag for stellar sources

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

Unattenuated Spectrum

Spectrum Attenuated

by IGM

B435 V606 z850

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


Lbg color selection
LBG color selection

B-dropouts, z~4

V-dropouts, z~5

Galaxies at z 6 6 8 of the cosmic age

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

S123 #5144: m(z) = 25.3

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

Dickinson et al. 2003

Observed redshift distribution
Observed redshift distribution




Curves from full

numerical simulations

Giavalisco et al. 2004, 2005



Spectra from

Bunker et al. 2003;

Stanway et al. 2003;

Vanzella et al. 2004

and the GOODS Team

Lbg luminosity function
LBG luminosity function

Apparently, very little evolution in the UV luminosity function

The history of the cosmic star formation activity
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.

a=-1.6 assumed

Giavalisco et al. 2004

Giavalisco et al. 2005, in prep.

Still uncertainty on measures
Still uncertainty on measures

  • 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

Bouwens et al. 2004

Sfr from x ray emission
SFR from X-ray emission

Lehmert et al 2005

See also Giavalisco 2002, ARA&A

Star formation rates
Star formation rates

z~4 B-band dropouts

Dust obscuration correction:

Calzetti starburst obscuration


B&C synthetic SED

Similar to what observed at


Sirtf imaging
SIRTF Imaging













5-σ limiting flux μJy

5-σ limiting AB mag

Stellar mass star formation

PAH + continuum (24 mm)

Far IR



+ near-IR

+ nebular lines


Stellar mass & star formation

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(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
Rest-optical & -IR at z~6

  • SST IRAC detections of z~6 galaxies

    => stellar population & dust fitting possible

ch1, 3.6mm


ch2, 4.5mm


Dickinson et al in prep

Luminosity Density versus

Color and Redshift

Papovich et al. 2003

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.

increase of ~33%

Implications for Galaxy Evolution

Dickinson, Papovich, Ferguson, & Budavari 2003

Implications for Galaxy Evolution

Dickinson, Papovich, Ferguson, & Budavari 2003

Stellar mass is

building up

We still need to

know how this

growth depends

on the total mass

Total mass of individual

galaxies seems to evolve

less rapidly:

bottles form first, wine

is added later

GOODS; Papovich et al. 2004

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
LBG morphology: light profiles

We measured the light

profiles and parametrized

them with the Sersic index

Ravindranath et al. 2005

Morphology of lbg
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 are


Ravindranath et al. 2005

z=0 disks

z=0 spheroids

Morphology of lbg the gini and m 20 coefficients
Morphology of LBG: the GINI and M20 coefficients



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)

Lotz, Madau, Giavalisco, Conselice & Ferguson 2005

Local galaxies at high redshift
Local galaxies at high redshift

Statistics calibrated using

local galaxies

Lotz et al. 2005

Lbg morphology
LBG morphology

Lotz et al. 2005

Lbg morphology1
LBG morphology

Lotz et al. 2005

Lbg morphology2
LBG morphology

Lotz et al. 2005

Infrequent morphological k correction
Infrequent “morphological k-correction”

WFPC2 (HDF) and

NIC3 J and H images

Internal color dispersion

consistent with relatively

young and homogeneous

stellar population

Dickinson 1998

Papovich, Giavalisco, Dickinson,

Conselice & Ferguson 2004

Papovich, Dickinson, Giavalisco

Conselice & Ferguson 2004

The evolution of galaxy size
The Evolution of galaxy size

  • First measures at these redshifts

    • Testing key tenets of the theory

  • Galaxies appear to grow hierarchically


Standard ruler


Ferguson et al. 2003

Galaxy clustering at high redshift
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
Clustering of star-forming galaxies at z~3

r0=3.3+/- 0.3 Mpc h-1

g = -1.8 +/- 0.15

Steidel et al. 2003

Adelberger et al. 1998

Giavalisco et al. 1998

Strong clustering massive halos
Strong clustering, massive halos


r0 =3.6 Mpc h-1

Porciani & Giavalisco 2002

Adelberger et al. 2004

local galaxies

m*>2.5E10 MO

m*>1.0E11 MO







Somerville 2004

Clustering segregation mass drives l uv sfr
Clustering segregationmass drives LUV (SFR)

GOODS Ground

Lee et al. 2005

Adelberger et al. (1998, 2004)

Giavalisco et al. (1998)

Giavalisco & Dickinson (2001)

Clustering segregation at z 4 and 5
Clustering segregation at z~4 and 5

Clustering segregation is detected

In the GOODS ACS sample at z~4

Consistent with other measures, e.g.

Ouchi et al. 2004

Lee et al. 2005

Halo sub structure at z 4
Halo sub-structure at z~4

We are observing

the structure within

the halo.

Break observed at

~10 arcsec

Note: 10 arcsec

at z~4 is about

~350 kpc.

See also Hamana

et al. 2004

Lee et al. 2005

The halo occupation distribution at z 4
The Halo Occupation Distribution at z~4

Consistent with Hamana et al. 2004

and Bullock et al. 2001





Lee et al. 2005

The halo occupation distribution at z 0
The Halo Occupation Distribution at z~0

a = 0.89 +/- 0.05

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

Mmin = 6.10 x 1012 MO

From SDSS data

Zehavi et al. 2004

Halos and galaxies at z 3 5
Halos and Galaxies at z~3-5

Halo substructure:

we observe an excess of faint

galaxies around bright ones.

massive halos contain more

than one LBG

“Bright Centers”: z_850<24.0

“Faint centers”: 24.0< z_850 <24.7

“Satellites”: z_850 >25.0

Lee et al. 2005

Halos and galaxies at z 3 51
Halos and Galaxies at z~3-5

Clustering scaling in good agreement

with hierarchical theory

Implied halo mass in the range

5x1010 – 1012 MO

1-σ scatter between mass and SFR

smaller that 100%

Giavalisco & Dickinson 2001

Porciani & Giavalisco 2002

Lee et al. 2004, in prep.

Eros or uv faint galaxies at z 2 3
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 quantified

and 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 about

50% of the volume density of LBGs

(highly uncertaint). However; they

possibly contribute about up to 100%

of the LBG stellar mass density, because

they have higher M/L ratios

Van Dokkum et al. 2004


Ks< 22, R-Ks>3.35

Moustakas et al. 2004


  • ACS resolution is crucial to

  • understand 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 eros1

Uses HUDF plus GOODS-SST data

SED fitting disfavour very dust

obscured, star-forming galaxies

SED better reproduced by a

two-component composite


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)

Yan et al. 2004

Lbgs at z 5 and 6
LBGs at z~5 and 6

Evidence of large stellar mass

at z~5, 6

Yan et al. 2005

Lbgs at z 5 and 61
LBGs at z~5 and 6

Evidence of large stellar mass

at z~5, 6

Yan et al. 2005

An evolved massive galaxy at z 7
An evolved, massive galaxy at z~7?


Mobasher et al. 2005, submitted to Nature

Nir selected galaxies
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


Daddi et al. 2004

Different populations
Different populations?

Near-IR selection

picks up the high-end

of the distribution of

masses (total and stellar)

Adelberger et al. 2004

Galaxies at z 1 0
Galaxies at z~1-0

Cosmic variance

Today’s stellar mass density

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 dominated

stellar mass density; the opposite

at z~0: morphology transformation

Bundy, Ellis & Conselice 2005

Ravindranath et al. 2003

  • Sersic indices n<2

  • Rest-frame MB <-19.5

  • Photometric redshifts

Disk galaxy evolution from goods ravindranath et al 2003
Disk galaxy evolution from GOODSRavindranath et al. 2003

Number-densities are

relatively constant to z~1

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

The evolutionary link
The evolutionary link?

The expected evolution of clustering

(correlation length) suggests what the

high redshift galaxies might evolve into

at later epochs.

Giavalisco, 2002 ARA&A

Adelberger et al. 2004


  • 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