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Andrea Grazian INAF - Osservatorio Astronomico di Roma

Evidence of a Fast Evolution of the UV Luminosity Function of LBGs beyond z=6 from a wide and deep HAWK-I Survey. Andrea Grazian INAF - Osservatorio Astronomico di Roma.

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Andrea Grazian INAF - Osservatorio Astronomico di Roma

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  1. Evidence of a Fast Evolution of the UV LuminosityFunction of LBGs beyond z=6 from a wide and deep HAWK-I Survey Andrea Grazian INAF - Osservatorio Astronomico di Roma M. Castellano, A. Fontana, K. Boutsia, R. Bouwens, S. Cristiani, M. Dickinson, F. Fiore, E. Giallongo, M. Giavalisco, A. Koekemoer, R, Maiolino, A. Moorwood, N. Menci, M. Nonino, L. Pentericci, A. Renzini, P. Rosati, S. Salimbeni, P. Santini, E. Vanzella

  2. Goals: • “exploration” of the Universe: observing galaxies, AGNs and structures up to the earliest phases of the Universe; • to reconstruct the history of fundamental physical quantites: Star Formation Rate, Stellar Mass, dust content, morphology, metallicity etc. • To Understand the physics involved. Develop and constrain theoretical models. Pb#1: How can we derive “physical quantities” from a handful of photons? Pb#2: We have to select complete galaxy samples by physical properties and not (only) by photometric criteria.

  3. Motivation of our ESO HAWK-I Large Program: • z=7 is fashionable; availability of HAWK-I. • COMPLEMENTARY to deep pencil beam surveys with WFC3 • Beat the cosmic variance: wide area survey. • Possibility to spectroscopically confirm our z=7 relatively bright candidates ESO LP 181.A.0717 (P.I. A. Fontana)

  4. HAWK-I is a newly-installed wide-field imager at the Nasmyth A focus of the 8 meter UT4 telescope (ESO, Paranal). It is provided with four 2048x2048 pixels detectors for a total field of view of 7.5'x7.5'. The pixel scale is 0.106". It has 10 observing filters: 4 broad band filters (Y, J, H & K) and 6 narrow band filters (Bracket gamma, CH4, H2, 1.061 μm, 1.187 μm & 2.090 μm).

  5. BDF4 GOODS-S NTTDF Deep IR Survey with Hawk-I & WFC3 Hawk-I Science Verification + ESO LP (HAWK-I+FORS2): (PI A. Fontana) WFC3 Early Science Release + Illingworth’s UDF data

  6. ACS - Z Hawk-I - Y Hawk-I is a powerful survey machine, even in WFC3 era. Yband WFC3- 1.5hr Hawk-I 15hr WFC3 4.7 sq. arcmin Hawk-I 56.3 sq. arcmin

  7. Hawk-I Y 15hr WFC3-J 22hr

  8. Z band z=6.8 Y band z=7 Lyman Break Galaxies at z=7 UV continuum Lyα

  9. An unexpected , large population of contaminants Y V B R I Z To clean the sample: “aggressive” requirement of non-detection in the UBVRI bands (ALL <2σ; 4 bands <1σ)

  10. z∼7 candidates in Hawk-I GOODS-S observations Castellano et al. 2009 arxiv:0909.2853

  11. Stacking of z∼7 candidates in Hawk-I GOODS-S Castellano et al. 2009 arxiv:0909.2853

  12. z∼7 candidates in Hawk-I BDF4 and NTTDF field Y Y

  13. Hawk-I candidates are consistent with WFC3 observations done so far. I Z Y105 J125 UDF B+V+I Z Y J+H+K Hawk-I

  14. “Counting” is not enough... need to evaluate systematics For each set of LF param (α,L*,φ) Extract expected galaxies in your field (LUV, z) Repeat N times Compute Magnitudes (AV, Lyα) Place them at random position in the image Perform multicolor extraction Retain the fraction selected with your favoured criterion For GOODS-S, about 104 simulations for 106 galaxies..

  15. Clear evidence of a fast evolution of the LF from z=6 to z=7 Castellano et al. 2009 arxiv:0909.2853 Hawk-I: bright &rare ERS: intermediate HUDF: faint & numerous

  16. Candidates @ z ≈ 7 in the WFC3 Bunker +09 arxiv:0909.2255 Oesch+ 09 arxiv:0909.1806 Yan+ 09 arxiv:0910.0077 McLure+ 09 arxiv 0909.2437

  17. Bouwens+09, arxiv:0909.1803 The SFRD(z): impact of the uncertainties of WFC3 data. Yan+09, arxiv:0910.0077

  18. Summary & Conclusions • Galaxies at z=7 and 8 are reliably detected with new generation IR imagers - Hawk-I and WFC3 are complementary at Y=25-27 - beyond WFC3 wins. • Data interpretation is complex -requires careful evaluation of instrumental and selection effects. • 60 hours of FORS2 already awarded for spectroscopy!! • Clear evidence for a fast evolution from z=6 to z=7 . beyond is controversial Castellano et al. 2009 (A&A in press) arXiv:0909.2853

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