Multi-wavelength Observations of Galaxies at z>~2 Mauro - - PowerPoint PPT Presentation

Multi-wavelength Observations of Galaxies at z>~2

Mauro Giavalisco (UMass)

+ The GOODS Team + The COSMOS Team

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 24µm MIPS studies:

• Selected range 1.4 < z < 2.5 places

strong mid-IR features in 24µm 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<z<2.5

GOODS: Great Observatories Origins Deep Survey

GOODS BzK

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

GOODS: Great Observatories Origins Deep Survey

Spectra of sBzK galaxies

27 COSMOS BzK <z>=1.87

Daddi et al., in prep.

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

GOODS: Great Observatories Origins Deep Survey

urface brightness prole 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

GOODS: Great Observatories Origins Deep Survey

Bulge-dominated BzKs

pBzK, Bulge-like (n>2.5):

sBzK, Bulge-like (n>2.5):

GOODS: Great Observatories Origins Deep Survey

Disk-dominated BzKs

pBzK, Disk-like (n< 2.5): sBzKDisk-like (n< 2.5):

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.

GOODS: Great Observatories Origins Deep Survey

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.

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COSMOS BzK galaxies

Bz from SUBARU K from CFHTdown to KVega = 21.3

McCracken et al. in prep.

~4x104 ~300

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

VLT/VIMOS

GOODS: Great Observatories Origins Deep Survey

Multi-wavelength measures of SFR

MIPS: <f(24µm)>=125 µJy, <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 µJy <LIR> = 2e12 Lo, <SFR> ~ 340 Mo/yr Sub-mm: stacked <f(850µm)> = 1.0 mJy (5) <LIR> = 1.0e12 Lo, <SFR> ~ 170 Mo/yr X-ray: stacked 8.5 soft-band detection, no significant hard-band. Far below expected AGN level. <SFR> = 100 - 500 Mo/yr (Persic 2004, Ranalli 2003 conversions) On average, multi-wavelength SFR tracers agree reasonably well with expectations from low-z correlations, templates & analogs.

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(24µm) / 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-, while less luminous sources match or fall below it (possibly including “passive” BzKs.

GOODS: Great Observatories Origins Deep Survey

Radio vs. 8 m

• Radio and mid-IR indicators agree at low

to medium luminosity, L(8µm)<~2x1011 LO

• For L(8µm)>2x1011 LO, LIR(mid-IR) in

excess over LIR(radio), as well as other estimators, compared to local templates: mid-IR excess All “monochromatic” luminosity transformed into bolometric IR luminosity (8-1000 µm) 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

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

GOODS: Great Observatories Origins Deep Survey

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?

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 LIR, and thus SFR, at high IR

• luminosity. Why?

UV,corr reliable estimator of SFR in most cases

GOODS: Great Observatories Origins Deep Survey

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)

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

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

GOODS: Great Observatories Origins Deep Survey

The mid-IR Excess (MIRX)

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

GOODS: Great Observatories Origins Deep Survey

Properties of mid-IR Excess Galaxies

GOODS: Great Observatories Origins Deep Survey

The SED of midr-IR Exess Galaxies

GOODS: Great Observatories Origins Deep Survey

The mid-IR galaxies

Fraction of mid-IR galaxies increases with mass,

GOODS: Great Observatories Origins Deep Survey

The origin of the mid-IR Excess: Hard Spectrum X-Ray Sources

0.5-2 keV 0.5-2 keV 2-8 keV 2-8 keV Normal Normal Excess Excess

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 NH~1025. In turn, this implies very large luministy, up to L~1045 erg/s

GOODS: Great Observatories Origins Deep Survey

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

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,

• bcuration

– 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

GOODS: Great Observatories Origins Deep Survey

Large Millimeter Telescope (LMT) U Mass – INAOE Mexico

Projected start of scientific observations at 3 mm ~Aug 2008

GOODS: Great Observatories Origins Deep Survey

LMT: a new powerful facility for (sub)-mm observations

• A 50-m aperture will greatly improve
• bservations at these critical wavelengths

– Higher mapping speeds big bolometer arrays – Higher flux sensitivity bigger telescopes – Less source confusion bigger telescopes – Source Redshifts new technologies

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

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

GOODS: Great Observatories Origins Deep Survey

AzTEC – Source Detection

• 1. improved accuracy in source-counts
• 2. greater dynamic range in source-counts

GOODS: Great Observatories Origins Deep Survey

Lyman-break galaxies ULIRGS Massive ellipticals ultra-massive, rare, starburst galaxies

LMT + AzTEC

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

GOODS: Great Observatories Origins Deep Survey

Redshift Search Receiver

Spectroscopic Redshift Survey

• 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

Red - no line

Yellow -one CO line Green - two CO lines

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

GOODS: Great Observatories Origins Deep Survey

Redshift Receiver System on the FCRAO and Haystack Telescope

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

• nly some 1000 objects

Photo-z can be obtained in

minutes using SPEED if

• ther data available (e.g.

VLA, Spitzer)

Photo-z good to 10%

Yun & Carilli (2002), Hughes et al. (2002)

GOODS: Great Observatories Origins Deep Survey

GOODS IRAC

• bservations have

identified a dozen candidates for even

• lder (~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

GOODS: Great Observatories Origins Deep Survey

z ~ 5 z ~ 6

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 3.6µm:

• H. Yan et al. 2005, 2006

GOODS: Great Observatories Origins Deep Survey

z~3 spectroscopy

Popesso et al., Vanzella et al. in prep. 2006

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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

GOODS: Great Observatories Origins Deep Survey

z~4 spectroscopy

Popesso et al, in prep.

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.

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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.

GOODS: Great Observatories Origins Deep Survey

Stellar populations of LBGs at z~5-6

(Yan et al. 2005; also Eyles et al. 2005)