Multi-wavelength Observations of Galaxies at z>~2

1. Multi-wavelength Observations of Galaxies at z>~2 Mauro Giavalisco (UMass) + The GOODS Team + The COSMOS Team

2. Colorselection at z~2: BzK galaxies BzK selection: 1.4<z<2.5 • BzK selection more general than UV selection (LBG). It is reddening independent and it includes: • Obscured star forming galaxies (larger range of obscuration) • Larger range of stellar masses • Passively evolving galaxies • Well suited for 24mm MIPS studies: • Selected range 1.4 < z < 2.5 places strong mid-IR features in 24mm band • Color selection includes objects with red UV continuum, e.g., from extinction • K-band selection suitable for relatively massive galaxies (Daddi et al. 2005)

3. GOODS BzK GOODS-S: 1080 galaxies, K<22.0 175 redshift (17%) GOODS-N: 273 galaxies, K<20.5 57 redshifts (21%)

4. Spectra of sBzK galaxies 27 COSMOS BzK <z>=1.87 Daddi et al., in prep.

5. Spectra of pBzKs VLT/FORS2 spectra of pBzKs in the UDF from GMASS w/ 30h integration VLT/VIMOS spectra of pBzKs from Kong et al w/ 2.5h integration

6. Surface brightness profile Analysis: • 2-D modeling using a single Sérsic function using GALFIT Software (Peng et al. 2002) Exponential disks: n = 1 R1/4 spheroids : n = 4 Ravindranath et al. 2007

7. Bulge-dominated BzKs pBzK, Bulge-like (n>2.5): sBzK, Bulge-like (n>2.5):

8. Disk-dominated BzKs pBzK, Disk-like (n< 2.5): sBzKDisk-like (n< 2.5):

9. Profile shapes of BzK Galaxies • About 40% of the pBzKs have bulge-like profiles with the fraction increasing to 60% when only the secure pBzKs are considered. • Star-forming BzKs mostly (80%) have low n (< 2.5) suggesting disk-like, irregulars, or mergers.

10. Size distributions • Passive BzKs have peak at re ≤ 0.25 arcsec (~ 2.1 kpc) with broad distribution that extends to compact sizes. • Star-forming BzKs are fairly symmetrically distributed about the peak at re ~ 3.5 kpc.

11. COSMOS BzK galaxies Bz from SUBARU K from CFHTdown to KVega = 21.3 ~3000 ~4x104 VLT/VIMOS K<20 Vega 64174 galaxies 7460 sBzK ~1/sq.arcmin 1548 pBzK ~0.2/sq.arcmin K<21.3 Vega 151974 galaxies 42105 sBzK 2923 pBzK McCracken et al. in prep.

12. Multi-wavelength measures of SFR On average, multi-wavelength SFR tracers agree reasonably well with expectations from low-z correlations, templates & analogs. MIPS: <f(24mm)>=125 mJy, <z>=1.9, and CE01 templates: <LIR> = 1.7e12 Lo, <SFR> ~ 300 Mo/yr UV continuum + reddening: <SFR> ~ 220 Mo/yr Radio: stacked VLA data <f(20cm)> = 17 mJy <LIR> = 2e12 Lo, <SFR> ~ 340 Mo/yr Sub-mm: stacked <f(850mm)> = 1.0 mJy (5s) <LIR> = 1.0e12 Lo, <SFR> ~ 170 Mo/yr X-ray: stacked 8.5s soft-band detection, no significant hard-band. Far below expected AGN level. <SFR> = 100 - 500 Mo/yr (Persic 2004, Ranalli 2003 conversions)

13. UV vs. IR SFRs: BzK-selected galaxies at z ~ 2 B-band samples ~1500A UV continuum at z~2; B-z measures UV continuum slope. f(24mm) / f(B) correlates strongly with B-z color, as expected if UV continuum slope results from dust reddening. Log scatter is a factor of ~3 (including effects of the broad BzK z-range). Brighter/more luminous mid-IR sources (LIR > 1012 Lo) tend to exceed expected IRX-b, while less luminous sources match or fall below it (possibly including “passive” BzKs.

14. Radio vs. 8 μm All “monochromatic” luminosity transformed into bolometric IR luminosity (8-1000 mm) using the Chary and Elbaz (2001) and Dale and Helou (2002) templates); Bolometric IR luminosity transformed into SFR using Kennicutt 1998 (the two used interchangeably) • Radio and mid-IR indicators agree at low to medium luminosity, L(8mm)<~2x1011 LO • For L(8mm)>2x1011 LO, LIR(mid-IR) in excess over LIR(radio), as well as other estimators, compared to local templates: mid-IR excess Daddi et al. 2007

15. 70 mm (warm dust emission) and 850 mm (cold dust emission) luminosity vs. midIR luminosity exhibit similar trends

16. UV vs. mid-IR derived SFR SFRUV,obscured = SFRUV,corr - SFRUV,uncorr Does the UV under-estimate the true SFR or is it the mid-IR over-estimating it compared to the local templates?

17. UV vs. Radio UV and radio-derived SFR agrees relatively well. This shows that for high luminosity mid-IR over-estimates LIR, and thus SFR, at high IR luminosity. Why? UV,corr reliable estimator of SFR in most cases

18. Recipe for SFR • If SFRUV,corr/SFR(8mm)<~3 • SFR = SFR(8mm) + SFRUV,uncorr • If (SFR(8mm)+SFRUV,uncorr)/SFRUV,corr<~3 • SFR = SFR(8mm) • If (SFR(8mm)+SFRUV,uncorr)/SFRUV,corr>~3 • SFR = SFRUV,corr • L(UV) corrected for obscuration using UV slope and Calzetti law provides reliable SFR estimates • The typical z~2 URLIG is transparent to UV radiation (not true for local ULRIG)

19. Tight SFR-Stellar Mass Correlation • Millennium sims predictions different: less SF and shallower slope • Significant population of ULIRG • Very different from local ones: • UV bright and transparent • Large duty cycle: 40% or ~0.5Gyr • Unlikely produced by mergers Green points from radio measures

20. Massive Galaxies at z~2 Sims make star-forming massive galaxies too soon Passive galaxies OK Duty cycle estimated from fraction of SF ULRIG in mass- and volume-limited sample: 0.4, corresponding to ~0.5 Gyr

21. The mid-IR Excess (MIRX) mid-IR excess observed in most galaxies with L(8mm)>2x1011 LO mid-IR excess responsible for galaxies with SFR(8mm)~1000 MO/yr (true SFR rarely exceeds a few MO/yr) For typical z~2 galaxies, local SED templates work Daddi et al. 2007b

22. Properties of mid-IR Excess Galaxies

23. The SED of midr-IR Exess Galaxies

24. The mid-IR galaxies Fraction of mid-IR galaxies increases with mass,

25. The origin of the mid-IR Excess: Hard Spectrum X-Ray Sources 2-8 keV 0.5-2 keV Excess Normal 0.5-2 keV 2-8 keV Normal Excess

26. The origin of the mid-IR Excess: Hard Spectrum X-Ray Sources Spectral shape implies very large column density, up to NH~1025. In turn, this implies very large luministy, up to L~1045 erg/s

27. Compton thick AGN • X-ray spectral index implies column density of about 1024-1025. • In turn, this implies X-ray luminosity up to ~1044 erg/s. AGN bolometric luminosity~SF bolometric luminosity • All this energy is released into the IGM. • Very energetic feedback consistent with that required to stop SF • Very large population of Compton thick AGN buried inside mid-IR BzK. • Contribution to X-ray background is modest: 10-15% • BH growth significantly larger than that of SMGs • Stellar and BH growth consistent with Magorrian relationship

28. Conclusions • BzK selection more general, representative of the mix at z~2 • Both active and passive galaxies included, with a larger spread of UV colors, obcuration • Larger morphological variety: bulges and disks are included • BzK galaxies at z~2 include significant faction of ULIRG, which are very different from local ones • UV bright and UV transparent; morphology not compact, often disk-like • Duty cycle of ULIRG phase is large, 40% or 0.5 Gyr, unlikely merger induced • Today these must be looked among very massive and old galaxies • Widesprerad presence of Compton-thick AGN in z~2 galaxies. • Fraction increases w/mass • Large deposition of energy into the IGM, LAGN~LSF. Feedback energy can eventually stop SF • More BH growth than in SMG; coeval growth of stellar and BH mass growth, consistent with today’s “Magorrian” relation • Modest contribution to XBL 10-15% at most

29. Large Millimeter Telescope (LMT)U Mass – INAOE Mexico Projected start of scientific observations at 3 mm ~Aug 2008

30. LMT: a new powerful facility for (sub)-mm observations • A 50-m aperture will greatly improve observations at these critical wavelengths • Higher mapping speeds big bolometer arrays • Higher flux sensitivity bigger telescopes • Less source confusion bigger telescopes • Source Redshifts new technologies

31. The LMT Submm Galaxy Program • First-generation LMT instruments chosen to address avariety of science topics • AzTEC – large FOV imaging for source detection • Redshift Search Receiver and 1mm Receiver – spectroscopic redshifts • SPEED – quickly measure SED • LMT + first generation instruments will provide a new view of faint sources and of the Far-IR background • Detect fainter sources with high angular resolution (~6 arcsec beam at 1 mm) • Improved measures of luminosity function • Study environments and link to large scale structure • Explore cosmic evolution of the population • LMT project scientist: Min Yun • AzTEC PI: Grant Wilson

32. The Deep Survey: 25 sq. arcmin to confusion limit (0.01mJy) 750 hrs, 1000 sources AzTEC/LMT Surveys for SMGs and SZE Clusters Large Area Survey: 30 sq. degrees 600 hrs, 100,000 sources 0.5 deg LMT/AzTEC simulation including high-redshift starburst galaxies, Galactic cirrus, Sunyaev-Zel’dovich clusters, Cosmic Microwave Background

33. AzTEC – Source Detection improved accuracy in source-counts greater dynamic range in source-counts

34. LMT + AzTEC Lyman-break galaxies ULIRGS Massive ellipticals ultra-massive, rare, starburst galaxies

35. S-COSMOS Cycle 2 sensitivity goals achieved !! S-COSMOS IRAC-deep sensitivities (5) S-COSMOS MIPS sensitivities (5) Galaxy SED templates + sensitivities vs. z (0.5, 1, 2, 3) LMT + AzTEC

36. Spectroscopic Redshift Survey Red - no line Yellow -one CO line Green - two CO lines Redshift Search Receiver • 36.5 GHz Bandwidth (74-110.5 GHz) • 90 km/s resolution • At least one CO line except for 0.4<z<1 and 2+ lines for z>2.8

37. Spectroscopy with Redshift Receiver System For dusty systems at high redshift, molecular lines may be ONLY way to measure z!

38. Redshift Receiver System on the FCRAO and Haystack Telescope

39. SPITZER CFRS14a (z=2.06) LMT+SPEED (5s) in 1 minute VLA (24hrs) Photometric redshifts with SPEED Yun & Carilli (2002), Hughes et al. (2002) • CO redshifts practical for only some 1000 objects • Photo-z can be obtained in minutes using SPEED if other data available (e.g. VLA, Spitzer) • Photo-z good to 10%

40. Unexpected “Big Babies” at z ~ 5-6 ? GOODS IRAC observations have identified a dozen candidates for even older (~700 Myr), more massive (up to ~10x the Milky Way!) galaxies at z~5-6. Spectroscopy has been impossible so far - but if correct, these would be unexpected in current galaxy formation models. Mobasher et al. 2005; Wiklind et al. 2007

41. GOODS/IRAC “weighs” and age dates galaxies at z~5-6. The red starlight seen by IRAC implies ages ~100-500 Myr, and masses up to that of the Milky Way. Substantial star formation took place during the reionization era at z ~ 7-9. IRAC 3.6m: z ~ 5 z ~ 6 H. Yan et al. 2005, 2006

42. z~3 spectroscopy Popesso et al., Vanzella et al. in prep. 2006

43. z~4 spectroscopy Variety of spectral “types” Very similar to the z~3 galaxies Emission of Lya observed together with weak interstellar absorption lines Stronger absorption lines are present when Lya is obsered in absorption Effect of geometry of ISM? Vanzella et al., Popesso et al., in prep. 2006

44. z~4 spectroscopy Popesso et al, in prep.

45. z~5 spectroscopy At z~5 and 6 selection effects make “emission” galaxies easier to confirm spectroscopically Vanzella et al. in prep.

46. Composite spectrum ofi-band dropouts The spectral properties of “observed” LBGs at z~6 are very similar to some LBGs observed at z~3. At z~6 it is very hard to obtain spectra of those LBGs with no Lya. Selection effect! Vanzella et al., Giavalisco et al 2006, in prep.

47. Stellar populations of LBGs at z~5-6(Yan et al. 2005; also Eyles et al. 2005)