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

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

6 High S/N Combined spectra Lyman-break

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 VVDS I AB ≤ % complete Redshift distribution I AB ≤24 Uncorrected for incompletness

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

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

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 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 Work in progress CENSUS IS DIFFICULT AT z~3 WORRISOME FOR z>3

13 Use VVDS to check color-color selection: ugr (LBG z~3) Confirmed spectro-z 2.7≤z≤3.5 Confirmed spectro-z z % 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 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 What are we looking for? Slits: 1”x5-20” VVDS main target Photometrically invisible Lya emitter Target spectrum Serendipitous 1216Å 1200 slits, covering 3.3 arcmin 2, Å, exp. times 65000s 8000 slits, covering 22.2 arcmin 2, Å, exp. times 16000s

16 The LAE sample Flux limit: ~2x erg.cm- 2.s 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 Combined spectra Ly  emitters Combined spectra Ly  line profile Asymetric, as expected

18 6 Ly  emitters at 6<z<6.6

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

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 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 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