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What is EVLA? Giant steps to the SKA-high

By building on the existing infrastructure, replace 1970’s electronics => multiply 10 to 100-fold the VLA’s observational capabilities. What is EVLA? Giant steps to the SKA-high. VLA + IRAM studies of galaxy formation. VLA Radio continuum = star formation

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What is EVLA? Giant steps to the SKA-high

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  1. By building on the existing infrastructure, replace 1970’s electronics => multiply 10 to 100-fold the VLA’s observational capabilities What is EVLA? Giant steps to the SKA-high

  2. VLA + IRAM studies of galaxy formation • VLA • Radio continuum = star formation • Low order CO = total gas mass, dynamics • Dense molecular gas tracers • Resolution down to 0.1” • Bure/30m • Dust = star formation • High order CO = gas excitation, ISM physics • Atomic FS Lines = gas cooling • Resolution down to 0.3”

  3. Star formation rate density vs. redshift z ~ 1 to 3: ‘epoch of galaxy assembly’ ~50% of stellar mass forms z>6: First light + cosmic reionization

  4. Star formation as function of galaxy stellar mass ‘active star formation’ specific SFR = SFR/M* 109 tH-1 ‘red and dead’ ‘Downsizing’ 1011 Eg. Zheng, Noeske, Damen… • Massive galaxies form most of their stars at high z • (see also: stellar pop. synthesis at low z; evolved galaxies at z ~1 to 2)

  5. UV correction factor ~ 5x Galaxy formation: optical limitations • Dust obscuration: rest frame UV needs substantial dust-correction, missing earliest, most intense epochs of star formation • Only stars and star formation: not (cold) gas => missing the other half of the problem = ‘fuel for galaxy formation’

  6. Obscuration-free SFR during epoch of galaxy assembly VLA observations of Cosmos • Full 2 deg2 at 1.4GHz • 1.5” resolution • rms ~ 10 uJy/beam • 4000 sources (10xHUDF) Mostly SF gal at z < 1 AGN, or extreme starburst at z>1: SFR > 1000 Mo yr-1

  7. Cosmos: 30,000 normal star forming galaxies (‘sBzK’) during epoch of galaxy assembly (zphot = 1.3 to 2.6) • Common ~ few x10-4 Mpc-3 (5arcmin-2) • M* ~ 1010 to 1011 Mo • HST sizes ~ 1” ~ 7kpc • ‘clump-cluster’/’chain’ galaxies (Elmegreen et al. 2007) • Hα IFU imaging => clumps = star forming regions in smoothly rotating, turbulent disk (Genzel et al. 2008) HST 2”

  8. VLA radio stacking: 30,000 sBzK in Cosmos <S1.4> = 8.8 +/- 0.1 uJy • <SFR> = 96 Mo yr-1 [FIR ~ 3e11 Lo] • VLA size ~ 1” ~ HST • [Who needs the SKA?!] Pannella +

  9. Stacking in bins of 3000 1010 Mo 3x1011 Mo • SFR ~ independent of blue magnitude • SFR increases with B-z => dust extinction increases with SFR (or M*) • SFR increases with stellar mass

  10. Dawn of Downsizing: SFR/M* vs. M* 1.4GHz SSFR • SSFR constant with M*, unlike z<1=> ‘pre-downsizing’ • z>1.5 sBzK well above the ‘red and dead’ galaxy line • UV dust correction = f(SFR, M*) [factor 5 at 2e10 Mo ~ LBG] z=2.1 z=1.5 5x tH-1 (z=1.8) z=0.3 UV SSFR

  11. 1.4 GHz uJy source counts (Bondi et al. 07) EVLA ~ sBzK • Flattening below 1mJy = star forming galaxies at intermediate z • Expect large population of z ~ 1 to 3 normal star forming galaxies (eg. sBzK ~ 5 arcmin-2) in EVLA deep field rms ~ 1 uJy

  12. CO observations of sBzK galaxies with Bure: Massive gas reservoirs Daddi + 2009 • 6 of 6 sBzK detected in CO • Gas mass ~ 1011 Mo • Gas masses ≥ stellar masses => early evolutionary phase

  13. VLA+Bure => Milky Way conditions: excitation, FIR/L’CO HyLIRG 1.5 Daddi + Dannerbauer + 1 First studies of normal galaxies during the dominant epoch of star formation in the Universe • Mgas ≥ M* => early evolutionary phase • MW conditions => Gas depletion timescales > few x108 yrs • SSFR => Active star formation over wide range in M*

  14. GN20 proto-cluster at z=4.05: A unique laboratory for studying massive galaxy formation within 2Gyr of Big Bang • SMG group GN20, GN20.2a,b: LFIR ~ 1013 Lo => SFR > 1000 Mo yr-1 • 15 LBGs at z ~ 4.06+/-0.02, within 1’ = 6x over-density • Detected CO1-0, 2-1, 4-3, 5-4, 6-5, (7-6) GN20.2b CO1-0 VLA CO 6-5 Bure GN20.2a GN20

  15. HST, CO2-1,FIR • GN20: Merger or cold mode accretion? • Highly obscured in optical • Big: 10kpc CO ring/disk • Resolved clumps ~ 1kpc (TB ~ 15K) • Rotation: Δv = 900 km/s CO2-1 0.45” CO2-1 0.15” 10kpc CO6-5

  16. Gas density history of the Universe EVLA+Noema CO deep fields Bell + H2 mass function z=0 SF law z=4 • Unbiased survey for cold gas: EVLA survey of 1.4e5 Mpc3 • 1000hrs, 50 arcmin2, νobs = 30 to 38GHz, down to 0.15” res. • z = 2 to 2.8 in CO 1-0 [CO 2-1 z=5 to 6.7] • Expect ~ 300 galaxies with M(H2) > 2e1010 Mo

  17. Correlator + Receiver Availability Timescale Today VLA Correlator WIDAR Correlator

  18. EVLA Status • Early science: Q1,2 2010 • complete18-50GHz (still can use old Rx <20GHz) • WIDAR with up to 2GHz • Resident shared risk proposal deadline: Tomorrow! • 8GHz available 2011 • Full receiver complement completed 2012.

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