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Understanding Properties of High-Redshift Lyman Break Galaxies

This study focuses on the properties of Lyman Break Galaxies (LBGs) at redshifts exceeding 5 through deep imaging and spectroscopy in multiple fields using advanced observational programs. The research investigates the distribution, redshifts, and evolutionary aspects of LBGs, providing valuable insights into star formation history and metal contribution to the intergalactic medium.

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Understanding Properties of High-Redshift Lyman Break Galaxies

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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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