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

Color selection at z~2: BzK galaxies GOODS: Great Observatories Origins Deep Survey BzK selection: 1.4<z<2.5 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 µ m MIPS studies: • Selected range 1.4 < z < 2.5 places strong mid-IR features in 24 µ 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)

GOODS BzK GOODS: Great Observatories Origins Deep Survey GOODS-S: 1080 galaxies, K<22.0 175 redshift (17%) GOODS-N: 273 galaxies, K<20.5 57 redshifts (21%)

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

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

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

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

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

Profile shapes of BzK Galaxies GOODS: Great Observatories Origins Deep Survey • 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.

Size distributions GOODS: Great Observatories Origins Deep Survey • 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.

COSMOS BzK galaxies GOODS: Great Observatories Origins Deep Survey Bz from SUBARU ~300 K from CFHTdown ~4x10 4 to K Vega = 21.3 0 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.

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

UV vs. IR SFRs: BzK- selected galaxies at z ~ 2 GOODS: Great Observatories Origins Deep Survey B-band samples ~1500A UV continuum at z~2; B-z measures UV continuum slope. f(24 µ 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 > 10 12 L o ) tend to exceed expected IRX- � , while less luminous sources match or fall below it (possibly including “passive” BzKs.

Radio vs. 8 � m GOODS: Great Observatories Origins Deep Survey All “monochromatic” luminosity transformed into bolometric IR luminosity (8-1000 µ 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) •Radio and mid-IR indicators agree at low to medium luminosity, L(8 µ m)<~2x10 11 L O •For L(8 µ 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 Daddi et al. 2007

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

UV vs. mid-IR derived SFR GOODS: Great Observatories Origins Deep Survey 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?

UV vs. Radio GOODS: Great Observatories Origins Deep Survey 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

Recipe for SFR GOODS: Great Observatories Origins Deep Survey • 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)

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

Massive Galaxies at z~2 GOODS: Great Observatories Origins Deep Survey 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

The mid-IR Excess (MIRX) GOODS: Great Observatories Origins Deep Survey mid-IR excess observed in most galaxies with L(8 µ m)>2x10 11 L O mid-IR excess responsible for galaxies with SFR(8 µ 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

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

The origin of the mid-IR Excess: Hard Spectrum X-Ray Sources GOODS: Great Observatories Origins Deep Survey 2-8 keV 0.5-2 keV Normal Excess 0.5-2 keV 2-8 keV Normal Excess

The origin of the mid-IR Excess: Hard Spectrum X-Ray GOODS: Great Observatories Origins Deep Survey Sources Spectral shape implies very large column density, up to N H ~10 25 . In turn, this implies very large luministy, up to L~10 45 erg/s

Compton thick AGN GOODS: Great Observatories Origins Deep Survey • X-ray spectral index implies column density of about 10 24 -10 25 . • 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

Conclusions GOODS: Great Observatories Origins Deep Survey • 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 today’s “Magorrian” relation • Modest contribution to XBL 10-15% at most

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

LMT: a new powerful facility for (sub)-mm observations GOODS: Great Observatories Origins Deep Survey • 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