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“Formation and evolution of galaxies from UV/optical-NIR surveys”

“Formation and evolution of galaxies from UV/optical-NIR surveys”. Lucia Pozzetti INAF Osservatorio Astronomico di Bologna. Outline. Why a survey in UV/optical or near-IR ? Statistical and theoretical instruments (LF, MF, SFH, SMH)

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“Formation and evolution of galaxies from UV/optical-NIR surveys”

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  1. “Formation and evolution of galaxies from UV/optical-NIR surveys” Lucia Pozzetti INAF Osservatorio Astronomico di Bologna

  2. Outline • Why a survey in UV/optical or near-IR ? • Statistical and theoretical instruments (LF, MF, SFH, SMH) • How derive intrinsic properties (L, M, SF) from observations • Models of galaxy evolution (Stellar Pop. Synthesis models) • Models of galaxy formation: Monolithic & Hierarchical • Local Universe (SDSS & 2dF, 2MASS) • Intermediate and High-z universe (VVDS, Deep2, K20, GMASS) • Star e Mass Formation History

  3. Photometric and redshift surveys: a key tool for cosmology Follow the evolution of Galaxies from the local to high-z universe to understand their nature: • how they formed • how they evolve • What are the main physical mecanisms at play and the associated timescales ? compare with models of galaxy formation and evolution 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

  4. SurveyUV/optical vs.near-IR Advantages of a UV/optical-selected sample (1500-9000 Å): • 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): • Less affected by dust extinction • 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

  5. Luminosity & Mass Functions Number of sources per units luminosity/mass and volume 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 Theoretical base: Press-Schechter for halo formation Statistical analysis in survey: Vmax, STY, c-method

  6. 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) LD + SFH (Madau, Pozzetti, Dickinson 1998) Star Formation History (Madau, et al. 1996) Stellar Mass Density (Dickinson et al. 2003)

  7. Photometric Redshifts The idea, due to Baum (1957), consists in determine theredshiftfrom multi-band photometry valuating the shift using different template of SED (χ2SED fitting technique) Allows to extend galaxy studies beyond the spectroscopic limits (R~25, K~19-20) (Bolzonella et al ‘00) redshift (Bolzonella, Miralles & Pello’ ‘00) z-photo

  8. Mass z_spec Mstar HyperZMass Estimate of the stellar Mass content from fitting of multi-band photometry with models of galaxy evolution

  9. Optical/UV SF indicators 1. UV continuum, λ = 2800Å Photospheric emission of O, B stars have a maximum in UV (Young stars t ~108yr) BUT Dust extinction ? 2. Ricombination line Hα,λ = 6563Å Idrogen ricombination of ionizing flux from Young stars t < 10 Myr, and massive M > 10Msun BUT escape fraction ? Dust extinction ? 3. Oxygen forbidden line [OII], λ = 3727Å Radiative diseccitation of HII region BUT it depends on Ionization state and gas metallicity. Calibrated on Ha. Also affected by dust extinction. + radio continuum (1.4 GHz) + FIR bolometric luminosity

  10. Models • Models of galaxy evolution (Stellar Pop. Synthesis models) • Models of galaxy formation: Monolithic & Hierarchical

  11. Models of stellar population synthesis ( 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)

  12. Properties Predictions Colors vs. time spectra vs. time (Bruzual & Charlot 2003)

  13. z=0 filter V z=0.5 Flux predictions • Observed flux and magnitudes

  14. Cosmological scenario 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 +

  15. Monolithic vs. Hierarchical 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 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

  16. cartoon MM Primordial gas z-form(mass)>3 z-form(stars)>3 Primordial gas HM z-form(stars)>3 z-form(mass)~1-2 redshift time

  17. High-redshift predictions • Decreasing of massive/old/red/ellipticals at z>1 and increasing of irregulars and mergers • SFH peaks at intermediate redshift (<20% stars at z>3) • Rapid evolution of the MF: steepening and less massive MONOLITHIC vs. HIERARCHICAL • Old passive ellipticals exist at z>1 and primordial elliptical (high SFR) at z>2-3 • SFH increases with redshift (50% stars formed at z>3) • Mild/negligible evolution of the MF z>1 SFR z=0 N Massa redshift

  18. Second Part: surveys • Local Universe (SDSS & 2dF & 2MASS) • Intermediate and High-z universe (VVDS, Deep2, K20, GMASS) • Star e Mass Formation History

  19. 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. Local Surveys: SDDS & 2DFGRS + 2MASS 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 telescopes The 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.

  20. Galaxy bimodality:luminous/massive objects are red/ellipticals/old SDDS Kauffman et al. 03 Brinchmann et al. 2004 Baldry et al. 2004 Specific SFR relation vs. Mass: SFR/M decrease with Mass MF and LF by color types:red galaxies dominate the luminouse/massive part of LF/MF (Baldry et al. 04, Bell et al. 03)

  21. Luminosity function in the optical (Norberg et al. 2002) yield the mean current star-formation rate 2dFGRS Ellipticals are more luminous Disks dominate the intermediate/low-luminosity end of LF The luminosity functions with different spectral types in the field (Folkes et al. 1999 and Madgwick et al. 2001)

  22. 2MASS + 2dFGRS : Near-infrared LF (J,Ks) (Cole et al. 2001) yielding the stellar mass function of galaxies 2MASS 2MASS + SDSS : MF also divided by color types (Bell et al. ’03)

  23. FDF ESO+FORS (UBgRIz) +SOFI(J,Ks)~5.6sq.arcmin I<26.8, 5557 zph 40 arcmin2 HDF-N (150 HST orbits WPC2 (U,B,V,I<28) + HDF-S UDF (412 orbits HST+ACS) Deep surveys from UV to NIR GOODSThe Great Observatories Origins Deep Survey 320 square arcminutes (HDFN+CDFS) : HST + SIRTF + ESO-spectra GMASS VLT+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 K20VLT FORS1 & FORS2 (PI Cimatti) Ks<20 52 arcmin^2 (CDFS+Q0055) U-Ks multi-band 92% redshift completeness GDDS (PI. Abraham)Gemini : K<20.6 I<24.5 1<z<2 MUNICS:(PI. Bender) 5000 gal (600 zsp) K<19.5, 0.4 deg2 COMBO 17(PI. Wolf) 796 gal. HAB<26.5, 1<zph<6

  24. VVDS: (PI Le Fevre) purely magnitude selected DEEP: 17.5<IAB<24, 1.2 deg² WIDE: 17.5<IAB<22.5, 10deg² Ultra-Deep: 22.5<IAB<24.75, 600 arcmin² multi-band photometry:GALEX SPITZER Intermediate z surveys 3000 Mpc Current volume sampled: 3x106 Mpc3 9600 redshifts 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 + …

  25. Excess in number counts at faint mag. from U to K • BUT No high-z galaxies at faint magnitudes (incompleteness ??) Evidence of Evolution in first surveys • Bluening of colors at faint magnitudes (Pozzetti et al. ’96)

  26. High-z selection criteria: LBGs 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 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

  27. LBG from HDF and other deep UV surveys Results:(ref.: Steidel, Madau, Adelberger, Giavalisco, Pettini,Bouwer,Mannucci) • SFR ~ 10-20 Msun/yr  SFH at high-z • Morphologies: compact o irr./multiple • Dimension: small rhl~0.2-0.3 arcsec (1-4 kpc) • LF: steep + bright and costant with z (decrease at z>6 ?) • Clustering: high-z spikes, high bias • Spectra: optical  local starbursts IR  dust-extinction • Sub-mm: low emission  low extinction • Masses: σ~70 km/s  Mdyn ~1010 Msun photometry Mstar ~ 1010 Msun clustering  Mhalo~1011 – 1012 Msun • “building blocks” of galaxy in HM !?

  28. STAR FORMATION HISTORY ..... z ---> 6 (Hopkins 2004) (Somerville et al 2001)

  29. 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

  30. EROs LBGs (Smith et al. ‘02) Results: (Daddi, Cimatti, Roche, Smith,...) • Morphologies: compact, disk or irr. • Counts: <= Local Ellipticals • Clustering: highA,ro • 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 (Daddi et al. ‘01) (Cimatti et al. ‘02)

  31. high-z selection criteria: BzK 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) (Daddi et al. ‘04)

  32. Old massive galaxies up to z=2 K20: Cimatti et al. 2004 GDDS: McCarthy et al. 2004 Saracco et al. 2005 Daddi et al. 2005 GMASS: Cimatti et al. ‘07

  33. Evolution of the luminosity function to z=1.2 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 Ilbert, et al., A&A, 2005, A&A, 439, 863 Ilbert et al., 2004 Zucca et al., 2006

  34. excess  deficit  K20: Luminosity Function in the near-IR • 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 

  35. Stellar Mass Function • Stellar Mass Function up to z~2 • (Fontana, Pozzetti, al. 04) : • Slow decrease (~50%) of mass density up to z~2 deficit Most of old hierarchical merging models do not match the above results BUT Hydrodinamical simulations match !!

  36. Iand K sel. Samples: Massfunction 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) Fontana et al. 06 Some HM better in the massive tail but overpredict low-mass end Pozzetti et al. 07

  37. Mass 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 Number density and SMH 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

  38. Mcross Bundy et al. 2006 Assembly of stellar mass per galaxy type: MF • 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 • Mcross evolves with redshift Transformation with cosmic time from active to passive galaxies From [OII]  Evolution mainly driven by SFR and no merging Vergani et al. arXiv:0705.3018

  39. MFs by morphological types: ELL., SPIRALand IRR.. 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

  40. Assembly of stellar mass per galaxy type: SMH 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” Arnouts et al., 2007,

  41. STAR FORMATION HISTORY&STELLAR MASS HISTORY ...SMH up to z --> 4 ...SFH up to z --> 6 Fontana et al. 06 (Hopkins 2004) (Somerville et al 2001)

  42. Local GMASS: Superdense quiescente galaxies • 13 ETG at 1.4<z<2. (z~1.6) massive (1010-1011 Msun) • 500 h stacked spectra + photometry: consistent with old (1 Gyrs stellar population M05) • Spheroidal and compact morphology • 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) Cimatti et al. 07 (submitted)

  43. Merging from pair fraction De Ravel et al., in prep • 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

  44. 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 = 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 Summary

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