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The bright end of the z ~ 7 UV Luminosity Function from a wide and deep HAWK-I survey
Astronomy & Astrophysics (2010)
  • M. Castellano
  • A. Fontana
  • D. Paris
  • A. Grazian
  • L. Pentericci
  • K. Boutsia
  • P. Santini
  • V. Testa
  • M. Dickinson
  • Mauro Giavalisco, University of Massachusetts - Amherst
  • R. Bouwens
  • J.-G. Cuby
  • F. Mannucci
  • B. Clément
  • S. Cristiani
  • F. Fiore
  • S. Gallozzi
  • E. Giallongo
  • R. Maiolino
  • N. Menci
  • A. Moorwood
  • N. Nonino
  • A. Renzini
  • P. Rosati
  • S. Salimbeni
  • E. Vanzella
(Abridged) We present here the second half of an ESO Large Programme, which exploits the unique combination of area and sensitivity provided in the near-IR by the camera Hawk-I at the VLT. We have obtained - 30 observing hours with Hawk-I in the Y-band of two high galactic latitude fields. We combined the Y-band data with deep J and K Hawk-I observations, and with FORS1/FORS2 U, B, V, R, I, and Z observations to select z-drop galaxies having Z - Y > 1, no optical detection and flat Y - J and Y - K colour terms. We detect 8 high-quality candidates in the magnitude range Y = 25.5 - 26.5 that we add to the z-drop candidates selected in two Hawk-I pointings over the GOODS-South field. We use this full sample of 15 objects found in -161 arcmin^2 of our survey to constrain the average physical properties and the evolution of the number density of z ~ 7 LBGs. A stacking analysis yields a best-fit SED with photometric redshift z= 6.85 +0.20 -0.15 and an E(B-V)=0.05 +0.15 -0.05. We compute a binned estimate of the z ~ 7 LF and explore the effects of photometric scatter and model uncertainties on the statistical constraints. After accounting for the expected incompleteness through MonteCarlo simulations, we strengthen our previous finding that a Schechter luminosity function constant from z=6 to z=7 is ruled out at a >99% confidence level, even including the effects of cosmic variance. For galaxies brighter than M_1500= -19.0, we derive a luminosity density rho_UV = 1.5^{+2.1}{-0.8} x 10^25 erg/s/Hz/Mpc^3, implying a decrease by a factor 3.5 from z=6 to z=6.8. We find that, under standard assumptions, the emission rate of ionizing photons coming from UV bright galaxies is lower by at least a factor of two than the value required for reionization. Finally, we exploit deep Hawk-I J and K band observations to derive an upper limit on the number density of M1500<~ -22.0 LBGs at z-8 (Y-dropouts).
  • Galaxies: distances and redshift,
  • Galaxies: evolution,
  • Galaxies: high redshift,
  • Galaxies: luminosity function
Publication Date
Publisher Statement
This paper was harvested from and ArXiv identifier is arXiv:1007.5396
Citation Information
M. Castellano, A. Fontana, D. Paris, A. Grazian, et al.. "The bright end of the z ~ 7 UV Luminosity Function from a wide and deep HAWK-I survey" Astronomy & Astrophysics (2010)
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