“Formation and evolution of galaxies

from UV/optical-NIR surveys”

Lucia PozzettiINAFOsservatorio Astronomico di Bologna

o Why a survey in UV/optical or near-IR ?o Statistical and theoretical instruments (LF, MF, SFH, SMH)

o How derive intrinsic properties (L, M, SF) from observations

o Models of galaxy evolution (Stellar Pop. Synthesis models)

o Models of galaxy formation: Monolithic & Hierarchical

o Local Universe (SDSS & 2dF, 2MASS) o Intermediate and High-z universe (VVDS, Deep2, K20,

GMASS)

o Star e Mass Formation History

Outline

Main steps of a survey:1. Band of selection + multi-band photometry2. Spectroscopy --> redshift is derived from the spectrum (from absorption or emission lines) distance is derived from the redshift and physical properties like Luminosity, Mass, SFR can be determined once the distance is known

Follow the evolution of Follow the evolution of Galaxies from the local to high-z universe to understand their nature:

o how they formedo how they evolveo What are the main physical mecanisms at play and the What are the main physical mecanisms at play and the

associated timescales ?associated timescales ?

compare with models of galaxy formation

and evolution

Photometric and redshift surveys: Photometric and redshift surveys: a key tool for cosmologya key tool for cosmology

Survey UV/optical vs. near-IR

Advantages of a UV/optical-selected sample (1500-9000 Å):

o Sensitive to the Star Formation / young stellar populations To search star forming objects at low and high-z (LBGs) To probe the optical/UV luminosity function and star

formation history

Telescopes: VLT, Keck, CFHT ... + HST + GALEX

Bands: FUV, NUV, U, B, G,V, R, I, z

Advantages of a near-IR-selected sample (1-5 m):o Less affected by dust extinctiono More sensitive to the stellar mass / old stellar populations To search massive old high-z (z>1) ellipticals (EROs, BzK) To probe the near-IR luminosity function and stellar mass function up to z~2

Telescopes: NTT, VLT, KecK ...+ HST + SPITZER

Bands: J, H, Ks, 3.6, 4.5, 5.4 micron

Galaxies follow a Schechter function:

Parameters depends on galaxy type:

Ellipticals are more luminous and massive

Disks dominate the intermediate/low-luminosity/massive end of LF/MF

Luminosity & Mass Functions

Theoretical base: Press-Schechter for halo formation

Statistical analysis in survey: Vmax, STY, c-method

<--- Luminosity / Mass

Number of sources per units luminosity/mass and volume

Number densities, star formation and mass assembly histories

Given the LFs / MFs / SFFs at different redshifts it is possible to reconstruct: 1- the number density evolution (gal/Mpc3 vs. z)2- the luminosity density evolution (erg/s/Hz/Mpc3 vs. z)3- the star formation history (Msun/yr/Mpc3 vs. z) (Madau/Lilly PLOT)4- the stellar mass assembly history (Msun/Mpc3 vs. z)

Stellar Mass Density (Dickinson et al. 2003)

Star Formation History (Madau, et al. 1996)

LD + SFH (Madau, Pozzetti, Dickinson 1998)

Photometric Redshifts

The idea, due to Baum (1957), consists in determine the redshift from multi-band photometry valuating the shift using different template of SED

( χ2 SED fitting technique)

Allows to extend galaxy studies beyond the spectroscopic limits (R~25, K~19-20)

redshift

z-photo

(Bolzonella et al ‘00)

(Bolzonella, Miralles & Pello’ ‘00)

Estimate of the stellar Mass content from fitting of multi-band photometry with models of galaxy evolution

Mass

Mstar

z_spec

HyperZMass

2. Ricombination line Hα, λ = 6563ÅIdrogen ricombination of ionizing flux from Young stars t < 10 Myr, and massive M > 10Msun

1. UV continuum, λ = 2800Å

Photospheric emission of O, B stars have a maximum in UV (Young stars t ~108yr)

3. Oxygen forbidden line [OII], λ = 3727Å Radiative diseccitation of HII region

+ radio continuum (1.4 GHz) + FIR bolometric luminosity

Optical/UV SF indicators

BUT escape fraction ?Dust extinction ?

BUT it depends on Ionization state and gas metallicity. Calibrated on Ha. Alsoaffected by dust extinction.

BUT Dust extinction ?

o Models of galaxy evolution (Stellar Pop. Synthesis models)

o Models of galaxy formation: Monolithic & Hierarchical

Models

( Tinsley 1978, Faber ’72, Bruzual ‘83, Arimoto & Yoshii ’86, Bruzual & Charlot ‘93, ‘03, ‘07, Maraston ‘05, Pegase, Jimenez ’04, Grasil, stardust )

Predict how Spectral Energy Distribution (SED) evolves with time:

Stellar tracks (m,t,Z) : MS Post-AGB (+ TP-AGB)Stellar spectra (observed + synthetic) + IMF(m)+ SFR(t)( + Z(t) chimical evolution )( + dust extinction & riemission in FIR)

SSP: Simple Stellar Population (coeval ages,Z) CSP: Composite Stellar Population (SFH)

Models of stellar population synthesis

Properties Predictions

spectra vs. time

(Bruzual & Charlot 2003)

Colors vs. time

Flux predictions

z=0

z=0.5

filter V

Observed flux and magnitudes

stellar population synthesis models

galaxy formation models

Monolithic (PLE) , Hierarchical

Number Counts N(m) Redshift distributions N(m,z) Color distributions N(m,c) LF, SFH, MF, SMH, EBL

Cosmological scenario

+

Monolithic vs. Hierarchical

White & Rees ’78, Cole etal. ’91

Kauffmann & White ’93

Galaxies (also ellipticals) form trough merging of smaller disk at intermediate redshift:

Similar masseselliptical

Different masses spiral

cosmological contest of CDM

Eggen,Lynden-Bell, Sandage ’62

Larson ’74

Galaxies (ellipticals and spirals) form at high redshift and evolve passively (no merging) with SFH with time scaling increasing from ell. to spiral

NO cosmological contest

MM

HM

redshifttime

z-form(mass)>3z-form(stars)>3

z-form(mass)~1-2 z-form(stars)>3

Primordial gas

Primordial gas

cartoon

o Decreasing of massive/old/red/ellipticals at z>1 and increasing of irregulars and mergers

o SFH peaks at intermediate redshift (<20% stars at z>3)

o Rapid evolution of the MF: steepening and less massive

o Old passive ellipticals exist at z>1 and primordial elliptical (high SFR) at z>2-3

o SFH increases with redshift (50% stars formed at z>3)

o Mild/negligible evolution of the MF

High-redshift predictionsMONOLITHIC vs. HIERARCHICAL

SFR

redshift Massa

N z=0

z>1

o Local Universe (SDSS & 2dF & 2MASS) o Intermediate and High-z universe (VVDS, Deep2, K20,

GMASS)

o Star e Mass Formation History

Second Part: surveys

Local Surveys: SDDS & 2DFGRS + 2MASS

Sloan Digital Sky Survey (SDSS) dedicated 2.5-m. tel. at Apache Point Obs. mapping a quarter of the sky.In 5 years, > 8,000 deg^2 in 5 bands (u’,g’,r’,i’,z’), detecting ~ 200 million obj., and spectra (r' < 18.15) of > 675,000 galaxies, 90,000 qso, and 185,000 stars.

The 2dF Galaxy Redshift Survey (2dFGRS) is a major spectroscopic survey the 2dF facility at the Anglo-Australian Obs.spectra for ~246000 obj., mainly galaxies, bJ<19.45. 22000 redshift measured area ~1500 square degrees

Two Micron All Sky Survey (2MASS) used two highly-automated 1.3-m telescopesThe first all-sky (~95%) photometric census (J,H,Ks bands) of galaxies brighter than Ks=13.5 mag(1,000,000 galaxies with J<15.0, H<14.3, Ks<13.5)The sky coverage have > 200 square degrees contiguos.

SDDS

Baldry et al. 2004

Kauffman et al. 03

Galaxy bimodality: luminous/massive objects are red/ellipticals/old

MF and LF by color types: red galaxies dominate the luminouse/massive part of LF/MF (Baldry et al. 04, Bell et al. 03)

Specific SFR relation vs. Mass:SFR/M decrease with Mass

Brinchmann et al. 2004

2dFGRS

Luminosity function in the optical (Norberg et al. 2002) yield the mean current star-formation rate

The luminosity functions with different spectral types in the field (Folkes et al. 1999 and Madgwick et al. 2001)

Ellipticals are more luminous Disks dominate the intermediate/low-luminosity end of LF

2MASS

2MASS + 2dFGRS : Near-infrared LF (J,Ks) (Cole et al. 2001) yielding the stellar mass function of galaxies

2MASS + SDSS :MF also divided by color types (Bell et al. ’03)

HDF-N (150 HST orbits WPC2 (U,B,V,I<28) + HDF-S

Deep surveys from UV to NIR

K20 VLT FORS1 & FORS2 (PI Cimatti) Ks<20 52 arcmin^2 (CDFS+Q0055) U-Ks multi-band 92% redshift completeness

UDF (412 orbits HST+ACS)

FDF ESO+FORS (UBgRIz) + SOFI(J,Ks) ~5.6sq.arcminI<26.8, 5557 zph 40 arcmin2

MUNICS: (PI. Bender) 5000 gal (600 zsp) K<19.5, 0.4 deg2

GOODS The Great Observatories Origins Deep Survey

320 square arcminutes (HDFN+CDFS) : HST + SIRTF + ESO-spectra

GMASSVLT+FORS2 LP (145h) (PI Cimatti)50 arcmin2 in the GOODS-South/HUDF m(4.5μm) < 23 (AB) + z(phot) > 1.4 Ultradeep spectroscopy to B=27, I=26, 11h-30h

COMBO 17 (PI. Wolf) 796 gal. HAB<26.5, 1<zph<6

GDDS (PI. Abraham) Gemini : K<20.6 I<24.5 1<z<2

Intermediate z surveys

3000 Mpc

VVDS:VVDS: (PI Le Fevre) (PI Le Fevre) purely purely magnitude selectedmagnitude selectedDEEP:DEEP: 17.5<I 17.5<IABAB<24, 1.2 deg²<24, 1.2 deg²WIDE:WIDE: 17.5<I 17.5<IABAB<22.5, 10deg²<22.5, 10deg²Ultra-Deep:Ultra-Deep: 22.5<I 22.5<IABAB<24.75, 600 <24.75, 600 arcmin²arcmin²multi-band photometry:GALEXmulti-band photometry:GALEX SPITZERSPITZER

DEEP2:Keck+DEIMOS (PI Davis) 19000 0.4<zphs<1.4 color-color selected, 4583 with zspec R<24.1, 1.5 deg2

COSMOS (PI Scoville) ~2 deg2

HST (640 orbits) + zCOSMOS (PI. S.Lilly: 40k redshift) + sCosmos + …

Current volume sampled: 3x106 Mpc3

9600 redshifts

Evidence of Evolution in first surveys

-Excess in number counts at faint mag. from U to K

-BUT No high-z galaxies at faint magnitudes (incompleteness ??)

-Bluening of colors at faint magnitudes

(Pozzetti et al. ’96)

High-z selection criteria: LBGs

color selection criteria:

U-dropout: 2<z<3.5

B-dropout: 3.5<z<4.5

V-dropout: 4.5<z<5.5

I-dropout: z~6

+ BM e BX : z=1.4-2.5

The IGM opacity (due to Lyman alpha forest and Lyman limit system) at high-z has been used to identified star forming galaxies at z>2 through colors which reveal the Lyman break

UV surveys

LBG from HDF and other deep UV surveys

Results: (ref.: Steidel, Madau, Adelberger, Giavalisco,

Pettini,Bouwer,Mannucci)

o SFR ~ 10-20 Msun/yr SFH at high-z

o Morphologies: compact o irr./multiple

o Dimension: small rhl~0.2-0.3 arcsec (1-4 kpc)

o LF: steep + bright and costant with z (decrease at z>6 ?)

o Clustering: high-z spikes, high bias

o Spectra: optical local starbursts

IR dust-extinction

o Sub-mm: low emission low extinction

o Masses: σ~70 km/s Mdyn ~1010 Msun

photometry Mstar ~ 1010 Msun

clustering Mhalo~1011 – 1012 Msun

“building blocks” of galaxy in HM !?

STAR FORMATION HISTORY

..... z ---> 6

(Hopkins 2004) (Somerville et al 2001)

EROs (Extremely Red Objects)Objects selected in NEAR-IR surveys with extremely red colors: R-K>5 o I-K>4 (Hu & Ridgway 1994)

Ellipticals at 1<z<2

BUT also

dusty SB at z>1 oabsorbed AGN

Results: (Daddi, Cimatti, Roche, Smith,...)

o Morphologies: compact, disk or irr.o Counts: <= Local Ellipticals o Clustering: highA,ro

o Spectra:

EROs

K20: First spectroscopic sample of EROs:(Cimatti et al. 02, Daddi et al. 02) :

31% old ellipticals @ z~1 age>~3 Gyrs, zform>2 33% dusty starbursts 20% of SFD @ z~1

(Smith et al. ‘02)

(Daddi et al. ‘01)

(Cimatti et al. ‘02)

EROs

LBGs

high-z selection criteria: BzK

(Daddi et al. ‘04)

New color selection criteria for SF and passive galaxies at 1.4<z<2.5

old galaxies up to z~1.9 (Cimatti et al. ’04)

Massive dusty starbursts at z~1.4-2.5 elliptical progenitors (Daddi et al. ’04)

From SINFONI: disk could become unstable (Genzel et al. 06)

Old massive galaxies up to z=2

K20: Cimatti et al. 2004GDDS: McCarthy et al. 2004Saracco et al. 2005Daddi et al. 2005

GMASS: Cimatti et al. ‘07

Ilbert, et al., A&A, 2005, A&A, 439, 863

TOTAL:~1.5-2 magnitudes of evolution at z~1.5-2

Type1=Ell.=LuminousType3,4=Spiral and Irr.=faintSimilar contribution to z=0 local LF

Type1=Ell.=ETG: evolution consistent with passive evolution and decrease <40%

Type4=Irr.: strong increase with redshift

Evolution of the luminosity function to Evolution of the luminosity function to z=1.2z=1.2

Zucca et al., 2006

Ilbert et al., 2004

Near-IR Luminosity Function up to z~2 (Pozzetti, et al. 03) :Passive luminosity evolution up to z~1-1.5Luminous red ellipticals fully in place up to z~1-1.5 Hierarchical deficiency of red/luminous galaxies at z~1 and excess of low-L

mild evolution deficit

excess

K20: Luminosity Function in the near-IR

Stellar Mass Function up to z~2(Fontana, Pozzetti, al. 04) : Slow decrease (~50%) of mass density up to z~2

Most of old hierarchical merging models do not match the above resultsBUT Hydrodinamical simulations match !!

deficit

Stellar Mass Function

I and K sel. Samples: Mass function

compatible results from the two samples in the common z range

Mild evolution up to z<0.9

Stronger evolution at z>0.9 in particular for intermediate/low mass galaxies

MF remain relatively flat up to z=2.5

Massive tail is present up to z~1 and decrease by a factor ~3 at z~2. (population of red gal. MI-MK~0.8)

Pozzetti et al. 07

Some HM better in the massive tail but overpredict low-mass end

Fontana et al. 06

Number density and SMHMass dependent evolution of the number/mass density (“mass downsizing”)

Negligible evolution of massive galaxies (>1011 Msun) (<30%) up to z=0.8

faster at higher-z (a factor of 3 at z=2)

Continuos evolution for intermediate/low-mass galaxies

Most massive galaxies seem in place up to z=1, formed their mass at z>1, less massive gal. have assembled their mass later and continuosly

Blue/ACTIVE gal. dominate at low-masses Small increase of intermediate-mass red/PASSIVE gal. with cosmic time. Massive tail present up to z=1.3Mcross evolves with redshift

Transformation with cosmic time from active to passive galaxies

Vergani et al. arXiv:0705.3018

Assembly of stellar mass per galaxy type: MFAssembly of stellar mass per galaxy type: MF

Bundy et al. 2006

Mcross

From [OII] Evolution mainly driven by SFR and no merging

Evolution by morphological types

Decrease of ELLIPTICALs at z>0.8. Small increase ofmassive SPIRAL (>1010 Msun) with z

Strong increase of IRREGULARs with z>0.5

MFs by morphological types: ELL., SPIRAL and IRR..

Assembly of stellar mass per galaxy type: Assembly of stellar mass per galaxy type: SMHSMH

Arnouts et al., 2007,

VVDS + Spitzer-SWIRE: complete 3.6m sample

the bright (massive) red galaxies are quickly assembling to z~1 build-up of the “red sequence”

STAR FORMATION HISTORY&

STELLAR MASS HISTORY...SFH up to z --> 6

(Hopkins 2004) (Somerville et al 2001)

...SMH up to z --> 4

Fontana et al. 06

GMASS: Superdense quiescente galaxies

o 13 ETG at 1.4<z<2. (z~1.6) massive (1010-1011 Msun)o 500 h stacked spectra + photometry: consistent with old (1 Gyrs stellar population M05)

Cimatti et al. 07 (submitted)

o Spheroidal and compact morphologyo Compact and superdense size ( Re~ 1 kpc) ~3 times smaller than z=0

Remnants of SMG (z>2) they evolve in z=0 ETG by dry-merging (3 major merging in 9 Gyrs, see Nipoti et al. 03) or envelope stars accretion (see Naab et al. 07)

Local

Controversial results (Bell et al. 06, van Dokkum 05, Lin et al. 04, see Renzini ‘07 for a review)

VVDS : pair fraction (1+z)m m~4.2- Most conservative: 8% of galaxies in pairs at z~0.8- L* galaxies experienced 0.5 to 1 major merger since z~1- low-z point is important: 2DFGRS, SDSS

De Ravel et al., in prep

Merging from pair fraction

Summary1- Local Universe, redshift <0.2:- Color-magnitude bimodality: ellipticals are old/massive/without SFR spiral are young/low-mass/high SFR

- Star formation increase from high to low mass galaxies

2- redshift = 0.2-1.5- Galaxies have similar properties and densities of local galaxies- Mass and type dependence evolution (downsizing)- Most massive galaxies seem in place up to z=1, formed stars and mass at z>1-2- Less massive/star forming galaxies have assembled mass continuosly and later- Passive evolution below z=0.7-1

3- redshift>1.5-2.- Population of low-mass SF objects (LBGs) “building blocks” of galaxy in HM !?

- Still old ETG massive galaxies but lower densities and superdense compact size evolve into old local ellipticals through dry-merging or envelope accretion- lower mass ETG continue to assembly down to lower redshift (downsizing)- New population of massive SF objects (SF BzK) gas-rich disks can become unstable or major mergers with gas-rich systems with major starburst triggered:- SMG phase characterized by short-lived 0.1 Gyrs) - the concomitant AGN provide enough feedback to quench sf in massive systems

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