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

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Presentation on theme: "Multi-wavelength Observations of Galaxies at z>~2 Mauro Giavalisco (UMass) + The GOODS Team + The COSMOS Team."— Presentation transcript:

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

2 GOODS: Great Observatories Origins Deep Survey Color selection at z~2: BzK galaxies BzK selection more general than UV selection (LBG). It is reddening independent and it includes: 1)Obscured star forming galaxies (larger range of obscuration) 2)Larger range of stellar masses 3)Passively evolving galaxies Well suited for 24 m MIPS studies: Selected range 1.4 < z < 2.5 places strong mid-IR features in 24 m 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) BzK selection: 1.4

3 GOODS: Great Observatories Origins Deep Survey GOODS BzK GOODS-S: 1080 galaxies, K< redshift (17%) GOODS-N: 273 galaxies, K< redshifts (21%)

4 GOODS: Great Observatories Origins Deep Survey Spectra of sBzK galaxies 27 COSMOS BzK =1.87 Daddi et al., in prep.

5 GOODS: Great Observatories Origins Deep Survey Spectra of pBzKs VLT/VIMOS spectra of pBzKs from Kong et al w/ 2.5h integration VLT/FORS2 spectra of pBzKs in the UDF from GMASS w/ 30h integration

6 GOODS: Great Observatories Origins Deep Survey Surface brightness profile Analysis: -2-D modeling using a single Sérsic function using GALFIT Software (Peng et al. 2002) Exponential disks: n = 1 R 1/4 spheroids : n = 4 Ravindranath et al. 2007

7 GOODS: Great Observatories Origins Deep Survey Bulge-dominated BzKs pBzK, Bulge-like (n>2.5): sBzK, Bulge-like (n>2.5):

8 GOODS: Great Observatories Origins Deep Survey Disk-dominated BzKs pBzK, Disk-like (n< 2.5): sBzKDisk-like (n< 2.5):

9 GOODS: Great Observatories Origins Deep Survey 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 GOODS: Great Observatories Origins Deep Survey Size distributions Passive BzKs have peak at r e 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 r e ~ 3.5 kpc.

11 GOODS: Great Observatories Origins Deep Survey COSMOS BzK galaxies Bz from SUBARU K from CFHTdown to K Vega = 21.3 McCracken et al. in prep. ~4x10 4 ~300 0 K<20 Vega galaxies 7460 sBzK ~1/sq.arcmin 1548 pBzK ~0.2/sq.arcmin K<21.3 Vega galaxies sBzK 2923 pBzK VLT/VIMOS

12 GOODS: Great Observatories Origins Deep Survey Multi-wavelength measures of SFR MIPS: =125 Jy, =1.9, and CE01 templates: = 1.7e12 L o, ~ 300 M o /yr UV continuum + reddening: ~ 220 M o /yr Radio: stacked VLA data = 17 Jy = 2e12 L o, ~ 340 M o /yr Sub-mm: stacked = 1.0 mJy (5 ) = 1.0e12 L o, ~ 170 M o /yr X-ray: stacked 8.5 soft-band detection, no significant hard-band. Far below expected AGN level. = M o /yr (Persic 2004, Ranalli 2003 conversions) On average, multi-wavelength SFR tracers agree reasonably well with expectations from low-z correlations, templates & analogs.

13 GOODS: Great Observatories Origins Deep Survey 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(24 m) / 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 (L IR > L o ) tend to exceed expected IRX-, while less luminous sources match or fall below it (possibly including passive BzKs.

14 GOODS: Great Observatories Origins Deep Survey Radio vs. 8 μm Radio and mid-IR indicators agree at low to medium luminosity, L(8 m)<~2x10 11 L O For L(8 m)>2x10 11 L O, L IR (mid-IR) in excess over L IR (radio), as well as other estimators, compared to local templates: mid-IR excess All monochromatic luminosity transformed into bolometric IR luminosity ( m) 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) Daddi et al. 2007

15 GOODS: Great Observatories Origins Deep Survey 70 m (warm dust emission) and 850 m (cold dust emission) luminosity vs. midIR luminosity exhibit similar trends

16 GOODS: Great Observatories Origins Deep Survey UV vs. mid-IR derived SFR SFR UV,obscured = SFR UV,corr - SFR UV,uncorr Does the UV under-estimate the true SFR or is it the mid-IR over- estimating it compared to the local templates?

17 GOODS: Great Observatories Origins Deep Survey UV vs. Radio UV and radio-derived SFR agrees relatively well. This shows that for high luminosity mid-IR over- estimates L IR, and thus SFR, at high IR luminosity. Why? UV,corr reliable estimator of SFR in most cases

18 GOODS: Great Observatories Origins Deep Survey Recipe for SFR If SFR UV,corr /SFR(8mm)<~3 –SFR = SFR(8mm) + SFR UV,uncorr If (SFR(8mm)+SFR UV,uncorr )/SFR UV,corr <~3 –SFR = SFR(8mm) If (SFR(8mm)+SFR UV,uncorr )/SFR UV,corr >~3 –SFR = SFR UV,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 GOODS: Great Observatories Origins Deep Survey 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 GOODS: Great Observatories Origins Deep Survey 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 GOODS: Great Observatories Origins Deep Survey The mid-IR Excess (MIRX) mid-IR excess observed in most galaxies with L(8 m)>2x10 11 L O mid-IR excess responsible for galaxies with SFR(8 m)~1000 M O /yr (true SFR rarely exceeds a few M O /yr) For typical z~2 galaxies, local SED templates work Daddi et al. 2007b

22 GOODS: Great Observatories Origins Deep Survey Properties of mid-IR Excess Galaxies

23 GOODS: Great Observatories Origins Deep Survey The SED of midr-IR Exess Galaxies

24 GOODS: Great Observatories Origins Deep Survey The mid-IR galaxies Fraction of mid-IR galaxies increases with mass,

25 GOODS: Great Observatories Origins Deep Survey The origin of the mid-IR Excess: Hard Spectrum X-Ray Sources keV 2-8 keV Normal Excess

26 GOODS: Great Observatories Origins Deep Survey The origin of the mid-IR Excess: Hard Spectrum X-Ray Sources Spectral shape implies very large column density, up to N H ~ In turn, this implies very large luministy, up to L~10 45 erg/s

27 GOODS: Great Observatories Origins Deep Survey Compton thick AGN X-ray spectral index implies column density of about In turn, this implies X-ray luminosity up to ~10 44 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 GOODS: Great Observatories Origins Deep Survey 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, L AGN ~L SF. Feedback energy can eventually stop SF More BH growth than in SMG; coeval growth of stellar and BH mass growth, consistent with todays Magorrian relation Modest contribution to XBL 10-15% at most

29 GOODS: Great Observatories Origins Deep Survey Large Millimeter Telescope (LMT) U Mass – INAOE Mexico Projected start of scientific observations at 3 mm ~Aug 2008

30 GOODS: Great Observatories Origins Deep Survey LMT: a new powerful facility for (sub)-mm observations A 50-m aperture will greatly improve observations at these critical wavelengths –Higher mapping speedsbig bolometer arrays –Higher flux sensitivitybigger telescopes –Less source confusionbigger telescopes –Source Redshiftsnew technologies

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

33 GOODS: Great Observatories Origins Deep Survey AzTEC – Source Detection 1. improved accuracy in source-counts 2. greater dynamic range in source-counts

34 GOODS: Great Observatories Origins Deep Survey Lyman-break galaxies ULIRGS Massive ellipticals ultra-massive, rare, starburst galaxies LMT + AzTEC

35 GOODS: Great Observatories Origins Deep Survey S-COSMOS IRAC-deep sensitivities (5 ) S-COSMOS MIPS sensitivities (5 ) Galaxy SED templates + sensitivities vs. z (0.5, 1, 2, 3) S-COSMOS Cycle 2 sensitivity goals achieved !! LMT + AzTEC

36 GOODS: Great Observatories Origins Deep Survey Redshift Search Receiver Spectroscopic Redshift Survey 36.5 GHz Bandwidth ( GHz) 90 km/s resolution At least one CO line except for Red - no line Yellow -one CO line Green - two CO lines

37 GOODS: Great Observatories Origins Deep Survey For dusty systems at high redshift, molecular lines may be ONLY way to measure z! Spectroscopy with Redshift Receiver System

38 GOODS: Great Observatories Origins Deep Survey Redshift Receiver System on the FCRAO and Haystack Telescope

39 GOODS: Great Observatories Origins Deep Survey Photometric redshifts with SPEED LMT+SPEED (5 ) in 1 minute CFRS14a (z=2.06) VLA (24hrs) SPITZER 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% Yun & Carilli (2002), Hughes et al. (2002)

40 GOODS: Great Observatories Origins Deep Survey 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. Unexpected Big Babies at z ~ 5-6 ? Mobasher et al. 2005; Wiklind et al. 2007

41 GOODS: Great Observatories Origins Deep Survey z ~ 5z ~ 6 GOODS/IRAC weighs and age dates galaxies at z~5- 6. The red starlight seen by IRAC implies ages ~ 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: H. Yan et al. 2005, 2006

42 GOODS: Great Observatories Origins Deep Survey z~3 spectroscopy Popesso et al., Vanzella et al. in prep. 2006

43 GOODS: Great Observatories Origins Deep Survey 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 GOODS: Great Observatories Origins Deep Survey z~4 spectroscopy Popesso et al, in prep.

45 GOODS: Great Observatories Origins Deep Survey z~5 spectroscopy At z~5 and 6 selection effects make emission galaxies easier to confirm spectroscopically Vanzella et al. in prep.

46 GOODS: Great Observatories Origins Deep Survey Composite spectrum of i-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 GOODS: Great Observatories Origins Deep Survey Stellar populations of LBGs at z~5-6 (Yan et al. 2005; also Eyles et al. 2005)


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