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The Properties of LBGs at z>5

The Properties of LBGs at z>5. Matt Lehnert (MPE) Malcolm Bremer (Bristol) Aprajita Verma (MPE) Natascha F ö rster Schreiber (MPE) and Laura Douglas (Bristol). Programs to Study z>5 LBGs. Deep Imaging and Spectroscopy of 4 fields of about 160 arcmin 2 with FORS2 on VLT

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The Properties of LBGs at z>5

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  1. The Properties of LBGs at z>5 Matt Lehnert (MPE) Malcolm Bremer (Bristol) Aprajita Verma (MPE) Natascha Förster Schreiber (MPE) and Laura Douglas (Bristol)

  2. Programs to Study z>5 LBGs Deep Imaging and Spectroscopy of 4 fields of about 160 arcmin2 with FORS2 on VLT ESO Large Program of Deep Imaging and Spectroscopy of 10 EDisCS fields Deep Spectroscopy of CDFS with GMOS on Gemini-South Pilot program to use GOODS-South IRAC data

  3. The VLT survey: LP + GO • 10 widely separated fields with deep VRIZJK data and HST I band + IRAC (~400 arcmin2) • Originally observed as part of the EDisCS cluster survey. Clusters usually low mass, lensing not a problem. • 4 Contiguous fields with deep RIZ+IRAC (~160 arcmin2) • Spectroscopy with the VLT, 1 to 5 masks each, depending on the richness  work is still on-going

  4. LBGs at z>5 • Example of six targets with measured redshifts. • All are R-band drop outs RAB>27.8 and (R-I)AB>1.5 Spectroscopic limit: IAB<26.3 Selected to match z~3 LBGs

  5. LBGs at z>5 8191.8Ǻ BDF1:10 z=5.774 8083.0Ǻ BDF2:19 z=5.645 7315.5Ǻ BDF1:18 z=5.017 8351.4Ǻ BDF1:19 z=5.870 7362.0Ǻ BDF1:26 z=5.056

  6. Example: One spectroscopically-completed field “Priority 1+2” targets

  7. Example: One spectroscopically-completed field Spectroscopically confirmed targets

  8. Redshifts in this one field Spike in the redshift distribution at z~5.1 9 sources Number Redshift

  9. Distribution of sources in this one field X-Y projection of z=5.1 3-D distribution of objects X-Y projection of all

  10. GOODS/CDFS • Lyman break colour selection (HST/ACS) • V-band dropouts V-I>1.7 • IAB<26.3 (comparable to our spectroscopic limit) • 3 non-detection in F435W (B) • 10 band multi-wavelength photometry • selection HST/ACS BVIz • VLT/ISAAC deep NIR JKs • Spitzer/IRAC deep MIR 3.6 4.5 5.8 8m 4.6<z<5.9 109 galaxies, stars & QSOs Or, an exercise in determining uncertainties and error analysis …

  11. Typical SED & SED modelling

  12. M zphot Properties of z>4.6 LBGs Multi-variate fit to SED ─ average probability distribution of most robust photometry ─ 21 sources • Bruzual & Charlot (2003) • Salpeter IMF • SMC-type extinction • Z=0.2 Z • 3 SFH: • Instantaneous burst • e-(t/) with =300Myr • Constant SF (to maximize ages)

  13. Properties of z>4.6 LBGs Contribution to the star-formation history determined using full SED Nagamine et al. (2006)

  14. Properties of z>4.6 LBGs Evolution of the stellar mass density Duty cycle ~10? >0.5% of stellar mass in place at z~5 Rudnick et al. (2006)

  15. log SFR (M yr-1 kpc-2) Winds Redshift Properties of z>4.6 LBGs Intensity of UV selected starbursts over a range of epochs Papovich et al. (2001), Heckman et al. (2005)

  16. Properties of z>4.6 LBGs Contribute significant metals to the IGM? f* = 0.5 ρSF~0.06 M yr-1 Mpc-3 Ώbh2=0.023 closure density dMSF/dt ≈ dMwinds/dt Z/Z≈0.2 Ncycle ≈ 10 f* = 0.1 f* = 0.01 Scannapieco et al. (2003), Songaila (2001)

  17. Summary Redshifts of well over 50 LBGs in ESO programs – more to come – more IRAC data to come tUV,optical < 100 Myrs and AV<0.3 (strong Ly emitters) MSED  few x 109M (10x < Mz3 LBGS) Star-formation rates = ~10 to ~100-200 M yr-1 zformation < 6-7 for majority, some earlier Ncycles ≈10 Likely drive vigorous winds (early enrichment?)

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