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 arcmin 2 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 arcmin 2 ) 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 arcmin 2 ) 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 R AB >27.8 and (R-I) AB >1.5 Spectroscopic limit: I AB <26.3 Selected to match z~3 LBGs

5. LBGs at z>5 BDF1:10 z=5.774 8191.8Ǻ 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 Number Redshift 9 sources

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

10. GOODS/CDFS Lyman break colour selection (HST/ACS) –V-band dropouts V-I>1.7 –I AB <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 JK s –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. 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) MM z phot

13. Sources are young: How Young? t dyn ≈ r/v =  √(r 3 /GM) ≈ few x 10 Myr SF has been proceeding for ~ one- 10 t dyn Starbursts: local examples recent large-scale SF events have comparable durations t star-formation ≈ few x 10 Myr

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

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

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

17. Properties of z>4.6 LBGs Scannapieco et al. (2003), Songaila (2001) ρ SF ~0.06 M  yr -1 Mpc -3 Ώ b h 2 =0.023 closure density dM SF /dt ≈ dM winds /dt Z/Z  ≈0.2 N cycle ≈ 10 f * = 0.5 f * = 0.1 f * = 0.01 Contribute significant metals to the IGM?

18. Summary Redshifts of well over 50 LBGs in ESO programs – more to come – more IRAC data to come t UV,optical < 100 Myrs and A V <0.3 (strong Ly  emitters) M SED  few x 10 9 M  (  10x < M z  3 LBGS ) Star-formation rates = ~10 to ~100-200 M  yr -1 z formation < 6-7 for majority, some earlier N cycles ≈10 Likely drive vigorous winds (early enrichment?)

19. Worries and Questions t UV,optical <10 8 yrs, M SED  few x10 9 M , and r e ≈1 kpc Duty cycle/temporal variations Cosmic variance (1+z) 4 Are all important? Missing sources? First Galaxies?