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

GOODS: Great Observatories Origins Deep Survey The Quest for the Early Galaxies During the mid-90s, 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 (1993, actual quote) were dismissed. Giavalisco 2002 ARA&A Ellis 1997 ARA&A

GOODS: Great Observatories Origins Deep Survey Abraham et al Lilly et al. 1995

GOODS: Great Observatories Origins Deep Survey Star-forming galaxies at z~3 (Lyman Break Galaxiess) Steidel, Giavalisco, Dickinson, Pettini & Adelberger 1996

GOODS: Great Observatories Origins Deep Survey Efficient star formation at z>2.5 Steidel, Adelberger, Giavalisco, Dickinson & Pettini 1999

GOODS: Great Observatories Origins Deep Survey 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 2003 Papovich, Dickinson, Giavalisco, Conselice & Ferguson 2004 Smaller Regulars, Irregulars, Merging, Spheroids? Disks? No Hubble Seq. No -dependence

GOODS: Great Observatories Origins Deep Survey UV-star formation rates Some rates are relatively low, ~ todays spirals; others are prodigiously high Metallicity ~1/10 to ~ solar Still an open issue

GOODS: Great Observatories Origins Deep Survey 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?

GOODS: Great Observatories Origins Deep Survey 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 NASAs Great Observatories (HST, Chandra, SIRTF), ESAs 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

GOODS: Great Observatories Origins Deep Survey 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 μ m –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: Great Observatories Origins Deep Survey

GOODS: Great Observatories Origins Deep Survey GOODS/ACS B = 27.5 V = 27.9 i = 27.0 z = 26.7 m ~ AB mag; S/N=10 Diffuse source, 0.5 diameter Add ~ 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: Great Observatories Origins Deep Survey 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 B 435 V 606 z 850 Unattenuated Spectrum Spectrum Attenuated by IGM B 435 V 606 i 775 z 850 z~4

GOODS: Great Observatories Origins Deep Survey LBG color selection B-dropouts, z~4 V-dropouts, z~5

GOODS: Great Observatories Origins Deep Survey 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

GOODS: Great Observatories Origins Deep Survey Observed redshift distribution V Z=5.78 Z=5.83 Z=6.24? Spectra from Bunker et al. 2003; Stanway et al. 2003; Vanzella et al and the GOODS Team Curves from full numerical simulations Giavalisco et al. 2004, 2005 #24

GOODS: Great Observatories Origins Deep Survey LBG luminosity function Apparently, very little evolution in the UV luminosity function

GOODS: Great Observatories Origins Deep Survey 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 Giavalisco et al. 2005, in prep. =-1.6 assumed

GOODS: Great Observatories Origins Deep Survey Still uncertainty on measures Bouwens et al 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

GOODS: Great Observatories Origins Deep Survey SFR from X-ray emission Lehmert et al 2005 See also Giavalisco 2002, ARA&A

GOODS: Great Observatories Origins Deep Survey Star formation rates Dust obscuration correction: Calzetti starburst obscuration law B&C synthetic SED Similar to what observed at z~3 z~4 B-band dropouts

GOODS: Great Observatories Origins Deep Survey SIRTF Imaging GOODS sensitivity σ limiting flux μ Jy 5- σ limiting AB mag

GOODS: Great Observatories Origins Deep Survey 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

GOODS: Great Observatories Origins Deep Survey Rest-optical & -IR at z~6 SST IRAC detections of z~6 galaxies => stellar population & dust fitting possible Dickinson et al in prep ch1, 3.6 m rest =5300A ch2, 4.5 m rest =6600A

GOODS: Great Observatories Origins Deep Survey 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

GOODS: Great Observatories Origins Deep Survey Implications for Galaxy Evolution Dickinson, Papovich, Ferguson, & Budavari 2003

GOODS: Great Observatories Origins Deep Survey Implications for Galaxy Evolution Dickinson, Papovich, Ferguson, & Budavari 2003 GOODS; Papovich et al 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: Great Observatories Origins Deep Survey 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)

GOODS: Great Observatories Origins Deep Survey Morphology of Lyman Break Galaxies at z~4 Bulges (n > 3.0) Central compact component / point sources? (n = 5.0)

GOODS: Great Observatories Origins Deep Survey LBG morphology: light profiles Ravindranath et al We measured the light profiles and parametrized them with the Sersic index

GOODS: Great Observatories Origins Deep Survey 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 observed. Ravindranath et al z=0 disks z=0 spheroids

GOODS: Great Observatories Origins Deep Survey Morphology of LBG: the GINI and M 20 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

GOODS: Great Observatories Origins Deep Survey Local galaxies at high redshift Statistics calibrated using local galaxies Lotz et al. 2005

GOODS: Great Observatories Origins Deep Survey LBG morphology Lotz et al. 2005

GOODS: Great Observatories Origins Deep Survey LBG morphology Lotz et al. 2005

GOODS: Great Observatories Origins Deep Survey LBG morphology Lotz et al. 2005

GOODS: Great Observatories Origins Deep Survey Infrequent morphological k-correction Dickinson 1998 Papovich, Giavalisco, Dickinson, Conselice & Ferguson 2004 Papovich, Dickinson, Giavalisco Conselice & Ferguson 2004 WFPC2 (HDF) and NIC3 J and H images Internal color dispersion consistent with relatively young and homogeneous stellar population

GOODS: Great Observatories Origins Deep Survey The Evolution of galaxy size Standard ruler R~H(z) -2/3 R~H(z) -1 First measures at these redshifts Testing key tenets of the theory Galaxies appear to grow hierarchically Ferguson et al. 2003

GOODS: Great Observatories Origins Deep Survey 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

GOODS: Great Observatories Origins Deep Survey Clustering of star- forming galaxies at z~3 Giavalisco et al Steidel et al Adelberger et al r 0 =3.3+/- 0.3 Mpc h -1 = /- 0.15

GOODS: Great Observatories Origins Deep Survey Strong clustering, massive halos Porciani & Giavalisco 2002 Adelberger et al =1.55 r 0 =3.6 Mpc h -1

GOODS: Great Observatories Origins Deep Survey local galaxies m*>2.5E10 M O m*>1.0E11 M O EROs sub-mm K20 SDSS QSOs LBGs Somerville 2004

GOODS: Great Observatories Origins Deep Survey Clustering segregation mass drives L UV (SFR) Adelberger et al. (1998, 2004) Giavalisco et al. (1998) Giavalisco & Dickinson (2001) GOODS Ground Lee et al. 2005

GOODS: Great Observatories Origins Deep Survey Clustering segregation at z~4 and 5 Lee et al Clustering segregation is detected In the GOODS ACS sample at z~4 Consistent with other measures, e.g. Ouchi et al. 2004

GOODS: Great Observatories Origins Deep Survey Halo sub-structure at z~4 Lee et al 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

GOODS: Great Observatories Origins Deep Survey The Halo Occupation Distribution at z~4 =(M/M 1 ) M>M min Lee et al Consistent with Hamana et al and Bullock et al

GOODS: Great Observatories Origins Deep Survey The Halo Occupation Distribution at z~0 From SDSS data Zehavi et al = / M 1 = (4.74 +/- 0.50) x M O M min = 6.10 x M O

GOODS: Great Observatories Origins Deep Survey Halos and Galaxies at z~3-5 Lee et al 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

GOODS: Great Observatories Origins Deep Survey Halos and Galaxies at z~3-5 Clustering scaling in good agreement with hierarchical theory Implied halo mass in the range 5x10 10 – M O 1- σ scatter between mass and SFR smaller that 100% Giavalisco & Dickinson 2001 Porciani & Giavalisco 2002 Lee et al. 2004, in prep.

GOODS: Great Observatories Origins Deep Survey EROs, or UV-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

GOODS: Great Observatories Origins Deep Survey EROs Ks 3.35 Moustakas et al. 2004

GOODS: Great Observatories Origins Deep Survey EROs ACS resolution is crucial to understand the nature of EROs Broad-band SED or statistical morphology cannot discriminate Evidence of massive galaxies at z~ Moustakas et al. 2004

GOODS: Great Observatories Origins Deep Survey HUDF/GOODS EROs Yan et al. 2004

GOODS: Great Observatories Origins Deep Survey HUDF/GOODS EROs Yan et al Uses HUDF plus GOODS-SST data SED fitting disfavour very dust obscured, 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: – M O Evidence that similar objects exist at z~7 (Mobasher et al. 2005)

GOODS: Great Observatories Origins Deep Survey LBGs at z~5 and 6 Yan et al Evidence of large stellar mass at z~5, 6

GOODS: Great Observatories Origins Deep Survey LBGs at z~5 and 6 Yan et al Evidence of large stellar mass at z~5, 6

GOODS: Great Observatories Origins Deep Survey An evolved, massive galaxy at z~7? Mobasher et al. 2005, submitted to Nature HUDF + GOODS-SST

GOODS: Great Observatories Origins Deep Survey NIR-selected galaxies NIR selected galaxies with K<20 VLT FORS spectra SED fits show M star >10 11 M O Claims that NIR selection yields more massive galaxies than UV selection Daddi et al. 2004

GOODS: Great Observatories Origins Deep Survey Different populations? Adelberger et al Near-IR selection picks up the high-end of the distribution of masses (total and stellar)

GOODS: Great Observatories Origins Deep Survey Galaxies at z~1-0 Evolution of the integrated mass density, M>10 11 M O 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 Cosmic variance Todays stellar mass density

Ravindranath et al –Sersic indices n<2 –Rest-frame M B <-19.5 –Photometric redshifts

GOODS: Great Observatories Origins Deep Survey Disk galaxy evolution from GOODS Ravindranath et al Tendency for smaller sizes at z~1 (30% smaller) Number-densities are relatively constant to z~1

GOODS: Great Observatories Origins Deep Survey The evolutionary link? Giavalisco, 2002 ARA&A The expected evolution of clustering (correlation length) suggests what the high redshift galaxies might evolve into at later epochs. Adelberger et al. 2004

GOODS: Great Observatories Origins Deep Survey 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; M min ~10 9 M O –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: 5x10 10 – M O