1. 1 VVDS: Towards a complete census of star formation at 1.4<z<~6 Olivier Le Fèvre Laboratoire d’Astrophysique de Marseille With the VIMOS VLT Deep Survey team Magnitude selected spectroscopic redshift survey – Ultra-deep VVDS sample Ly  flux limited spectroscopic redshift survey Improved galaxy census

2. 2 Understanding galaxy evolution at z>1.4 requires a complete census Star formation, mass assembly history, are derived from galaxy counts Are we making a reasonably complete census of star- forming galaxies ? –Color pre-selection vs. flux selection Hard job: only 3-4% of AB~25 galaxies are at z>1.4 SFH, Mass assembly,… LF/LD, clustering, merger rate Spectroscopic samples Sample selection Photom etry Astronomy Astro-Physics

3. 3 Making a complete census COLOR SELECTIONMulti-color imaging Object detection + catalog Color-color selectionSpectroscopy / RedshiftSpectro incompletnessImaging incompletness Counts / LF / LD / SFH FLUX SELECTIONSingle band imaging Object detection + catalog Spectroscopy / RedshiftSpectro incompletness Counts / LF / LD / SFH Hypotheses f(m,z) Simulations g(m,size, SB, color) Seeing LBG, BzK DRG, SMG, EROs, NB,… I, K, 3.6µm,… Em. line g(m,size,SB,color): uncertain for faint high-z objects

4. 4 VVDS: magnitude limited samples SampleSelectionredshift# galaxies Spectro-z # galaxies z>1.4 WideI AB ≤22.50<z<1.535000- DeepI AB ≤240<z<512000970 Ultra-DeepI AB ≤24.750<z<5863409 Ly  Flux2<z<6.5204 A total of ~1580 galaxies with 1.4<z<6.6 and spectroscopic redshifts Check http://cencosnew.oamp.fr/ for public datahttp://cencosnew.oamp.fr/ VLT-VIMOS

5. 5 New Ultra-Deep sample Magnitude selected I AB ≤24.75 863 galaxies targeted with VLT-VIMOS 262 re-observed from failed I AB ≤24 18h integrations in blue + 18h integrations in red, 3600-9350A coverage 86% complete

6. 6 High S/N Combined spectra Lyman-break

7. 7 « Bean counting » Producing accurate redshift distributions N(z,m) Completness of redshift measurements –Minimized with re-observed samples Two independant observations Reobserved objects with longer integration times –Tested with photometric redshifts

8. 8 VVDS I AB ≤24 2005 80% complete Redshift distribution I AB ≤24 Uncorrected for incompletness

9. 9 Redshift distribution I AB ≤24 VVDS I AB ≤24, corrected 2009 96% complete Corrected for incompletness Corrected for incompletness using high success rate in re-observed sample with 3700-9300A wavelength coverage and 4.5x exposure time Failed on first attempt I AB ≤24 sample, now re-observed with secure z

10. 10 Redshift distribution I AB ≤24.75 VVDS-Udeep I AB ≤24.75 863 objects New ultra-deep sample z_median=1.4 86% complete Well into redshift desert because of the 3600-9350A coverage

11. 11 Aposteriori comparison spectroscopic vs. Photometric redshifts LBG Spectacular agreement: High quality photometry trained on High quality spectroscopic redshifts Ilbert et al., in prep.

12. 12 Galaxy number density at z~3 Use N(z) Corrected I AB ≤24 Uncorrected I AB ≤24.75 ~2x more galaxies in magnitude limited survey than in LBG, for all mag I AB  22 Confirms Le Fèvre et al. 2005 Work in progress CENSUS IS DIFFICULT AT z~3 WORRISOME FOR z>3

13. 13 Use VVDS to check color-color selection: ugr (LBG z~3) Confirmed spectro-z 2.7≤z≤3.5 Confirmed spectro-z z 3.5 60% contamination15% not selected LBG Exquisite photometry From CFHTLS Main source of uncertainty from color selection: the depth of photometry Black: z<2.7 Green: stars VVDS spectro: Not-LBG

14. 14 Census of LAE: The VVDS Ly  emitters sample Search for serendipitous emission in the slits of the VVDS Deep and Ultra-Deep observations Use the large wavelength coverage to isolate Ly  systems Use the exact knowledge of the sky background to estimate the flux limit F( ) A complete flux limited LAE survey

15. 15 What are we looking for? Slits: 1”x5-20” VVDS main target Photometrically invisible Lya emitter Target spectrum Serendipitous Lya @ 1216Å 1200 slits, covering 3.3 arcmin 2, 3500-9500Å, exp. times 65000s 8000 slits, covering 22.2 arcmin 2, 5500-9500Å, exp. times 16000s

16. 16 The LAE sample Flux limit: ~2x10 -18 erg.cm- 2.s -1 86 Lya from UDeep blue 25 Lya from UDeep red 27 Lya from Deep 66 spectroscopy main targets 204 emitters The largest LAE sample with spectroscopy confirmed z

17. 17 Combined spectra Ly  emitters Combined spectra Ly  line profile Asymetric, as expected

18. 18 6 Ly  emitters at 6<z<6.6

19. 19 Redshift and Luminosity distribution UDeep blue UDeep red Deep First exploration at faint luminosities 10 41 erg/s

20. 20 LAE Luminosity function No apparent evolution from z=2 to z=6.6 But evolution when including dust and IGM corrections we reach log(lum)=41erg/s: we can constrain  Black: literature z=3-6  =1.75

21. 21 Star formation density from LAE No correction for dust No correction for IGM absorption Constant SFD from z=2 to z=6 Ly  contributes to 20% of the SFD at z=2.5, 30% at z=5, >50% at z=6 Cassata et al., submitted If Lya emission is coming from Star Formation…

22. 22 Summary Galaxy studies at z>1 require complete magnitude-selected deep spectroscopic surveys Star-forming galaxy census at z>1 is not complete yet UV-continuum selection spectroscopic survey counts ~2x more galaxies at z~3 as compared to color-selection (LBG) Color-color selection has build-in inaccuracy Faint Ly  emitters with log(Ly  )<42 are numerous, LF slope  =1.7 at z~2-6 Ly  SFRD is 30% of the total SFRD at z~3, becoming dominant at z~6 New deep redshifts surveys are required to make progress