Formation and evolution of galaxies from UV/optical-NIR surveys Lucia Pozzetti INAF Osservatorio 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 photometry 2. 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 formed o how they evolve o What are the main physical mecanisms at play and the associated timescales ? compare with models of galaxy formation and evolution Photometric and redshift surveys: a key tool for cosmology

Survey UV/optical vs. near-IR Advantages of a UV/optical-selected sample ( 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 extinction o 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/Mpc 3 vs. z) 2- the luminosity density evolution (erg/s/Hz/Mpc 3 vs. z) 3- the star formation history (Msun/yr/Mpc 3 vs. z) (Madau/Lilly PLOT) 4- the stellar mass assembly history (Msun/Mpc 3 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 ( χ 2 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 MassMass Mstar z_spec HyperZMass

2. Ricombination line H α, λ = 6563Å Idrogen ricombination of ionizing flux from Young stars t 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. Also affected 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

Codici di sintesi di popolazione o GISSEL (Bruzual & Charlot , Jimenez 2004) UV near-IR varie Z + emissione nebulare (Charlot & Longhetti 01) o STARDUST (Devriendt, Guiderdoni & Sadat 99) Far-UV Radio Z(t), polvere assorbimento e riemissione o GRASIL (Silva & Granato 98) Far-UV Far-IR polvere assorbimento e riemissione o PEGASE (Fioc & Rocca-Volmerange 98) UV near-IR polvere assorbimento e riemissione o M05 (Maraston 05) TP-AGB

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 masses elliptical 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 redshift time z-form(mass)>3 z-form(stars)>3 z-form(mass)~1-2 z-form(stars)>3 Primordial gas cartoon

Hierarchical models DM + GRAVITY BARIONS Amplitude growing : linear regime δρ / ρ 1 non linear regime simulations N-body dissipationless for accretion and mergers of small units Dissipative condensation in halo center dynamical friction, ram-pressure stripping, mergers Similar masses ellittiche (Barnes 88) different masses spirali (Toth & Ostriker 92) merger tree (SN,wind +AGNs) Primordial fluctuations Formation of DM halo Halo Merging Barions formation disk formation Cooling / Star-formation / feedback stellar evolution dynamical process Merging of disks massive gal. formation +bursts, dust + AGN

MODELLI GERARCHICI o SAM: simulazioni N-body per DM + merging-tree per merging galassie + modelli analitici per cooling-dinamica-sfr Codici : Durham Frenk, Cole, Baugh Munich White, Kauffmann Paris Guiderdoni, Devrient Santa-Cruz Primack, Somerville Roma Menci o Modelli idrodinamici: simulazioni N-body per DM + simulazioni idrodinamiche per i barioni, gas Codici : Nagamine, Ostriker, Hernquist, Springel o Modelli antigerarchici (coevolution AGN+gal.): Codici : Granato, Menci

o Decreasing of massive/old/red/ellipticals at z>1 and increasing of irregulars and mergers o SFH peaks at intermediate redshift ( 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 predictions MONOLITHIC vs. HIERARCHICAL SFRSFR 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' 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 ~ obj., mainly galaxies, b J < redshift measured area ~1500 square degrees Two Micron All Sky Survey (2MASS) used two highly-automated 1.3-m telescopes The first all-sky (~95%) photometric census (J,H,Ks bands) of galaxies brighter than K s =13.5 mag (1,000,000 galaxies with J<15.0, H<14.3, K s <13.5) The sky coverage have > 200 square degrees contiguos.

SDDS Baldry et al 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 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.arcmin I<26.8, 5557 zph 40 arcmin2 MUNICS: (PI. Bender) 5000 gal (600 zsp) K<19.5, 0.4 deg 2 GOODS The Great Observatories Origins Deep Survey 320 square arcminutes (HDFN+CDFS) : HST + SIRTF + ESO-spectra GMASS VLT+FORS2 LP (145h) (PI Cimatti) 50 arcmin 2 in the GOODS-South/HUDF m(4.5 μ m) 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: (PI Le Fevre) purely magnitude selected DEEP: 17.5<I AB <24, 1.2 deg² WIDE: 17.5<I AB <22.5, 10deg² Ultra-Deep: 22.5<I AB <24.75, 600 arcmin² multi-band photometry:GALEX SPITZER DEEP2: Keck+DEIMOS (PI Davis) <zphs<1.4 color-color selected, 4583 with zspec R<24.1, 1.5 deg2 COSMOS (PI Scoville) ~2 deg 2 HST (640 orbits) + zCOSMOS (PI. S.Lilly: 40k redshift) + sCosmos + … Current volume sampled: 3x10 6 Mpc 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= 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) oSFR ~ Msun/yr SFH at high-z oMorphologies: compact o irr./multiple oDimension: small r hl ~ arcsec (1-4 kpc) oLF: steep + bright and costant with z (decrease at z>6 ?) oClustering: high-z spikes, high bias oSpectra: optical local starbursts IR dust-extinction oSub-mm: low emission low extinction oMasses: σ ~70 km/s M dyn ~10 10 Msun photometry M star ~ Msun clustering M halo ~10 11 – 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 o absorbed AGN

Results: (Daddi, Cimatti, Roche, Smith,...) oMorphologies: compact, disk or irr. oCounts: <= Local Ellipticals oClustering: highA,r o oSpectra: EROs K20: First spectroscopic sample of EROs: (Cimatti et al. 02, Daddi et al. 02) : 31% old z~1 age>~3 Gyrs, zform>2 33% dusty starbursts 20% of 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~ 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 GDDS: McCarthy et al Saracco et al Daddi et al GMASS: Cimatti et al. 07

Redshift distribution (Cimatti, Mignoli et al. 02, Cimatti, Pozzetti et al. 02): Substantial population at high-z (32% at z>1) Underpredicted by hierarchical models deficit excess SURVEY K20

Ilbert, et al., A&A, 2005, A&A, 439, 863 TOTAL: ~1.5-2 magnitudes of evolution at z~1.5-2 Type1=Ell.=Luminous Type3,4=Spiral and Irr.=faint Similar 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 z=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~1-1.5 Luminous 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 results BUT 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. M I -M K ~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 SMH Mass dependent evolution of the number/mass density (mass downsizing) Negligible evolution of massive galaxies (>10 11 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=1.3 M cross evolves with redshift Transformation with cosmic time from active to passive galaxies Vergani et al. arXiv: Assembly of stellar mass per galaxy type: MF Bundy et al M cross 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 (>10 10 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: SMH Arnouts et al., 2007, VVDS + Spitzer-SWIRE: complete 3.6 m 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 ( Msun) o 500 h stacked spectra + photometry: consistent with old (1 Gyrs stellar population M05) Cimatti et al. 07 (submitted) o Spheroidal and compact morphology o 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

Summary 1- 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 = 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= redshift> 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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