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The size-luminosity relation at z=7 in CANDELS and its implication on reionization
Astronomy & Astrophysics (2012)
  • A. Grazian
  • M. Castellano
  • A. Fontana
  • L. Pentericci
  • J. S. Dunlop
  • R. J. McLure
  • A. M. Koekemoer
  • M. E. Dickinson
  • S. M. Faber
  • H. C. Ferguson
  • A. Galametz
  • Mauro Giavalisco, University of Massachusetts - Amherst
  • N. A. Grogin
  • N. P. Hathi
  • D. D. Kocevski
  • K. Lai
  • J. A. Newman
  • E. Vanzella
The exploration of the relation between galaxy sizes and other physical parameters has given important clues to understand the galaxy formation processes. We use the CANDELS Deep+Wide surveys in the GOODS-South, UDS and EGS fields, complemented by data from the HUDF09 program, to address the relation between size and luminosity at z\sim7. We select 153 z-band drop-out galaxies in six different fields characterized by a wide combination of depth and areal coverage, ideally suited to sample without biases the observed size-magnitude plane. Detailed simulations allow us to derive the completeness as a function of sizes and magnitudes and to quantify measurements errors/biases. We find that the half light radius distribution function of z\sim7 galaxies fainter than J=26.6 is peaked at <0.1 arcsec (or equivalently 0.5 kpc proper), while at brighter magnitudes high-z galaxies are typically larger than \sim0.15 arcsec. We also find a well defined size-luminosity relation, Rh\simL^1/2. We compute the Luminosity Function in the HUDF and P12HUDF fields, finding large spatial variation on the number density of faint galaxies. Adopting the size distribution and the size-luminosity relation found for faint galaxies at z=7, we derive a mean slope of -1.7+/-0.1 for the luminosity function of LBGs at this redshift. Using this LF, we find that the amount of ionizing photons cannot keep the Universe re-ionized if the IGM is clumpy (C_HII>3) and the Lyman continuum escape fraction of high-z LBGs is relatively low (f_esc<0.3). With future CANDELS data, we can put severe limits to the role of galaxies in the reionization of the Universe.
  • Galaxies:distances and redshift,
  • Galaxies: evolution,
  • Galaxies: high redshift,
  • Galaxies: structure
Publication Date
Publisher Statement
This paper was harvested from and ArXiv identifier is arXiv:1208.0506
Citation Information
A. Grazian, M. Castellano, A. Fontana, L. Pentericci, et al.. "The size-luminosity relation at z=7 in CANDELS and its implication on reionization" Astronomy & Astrophysics (2012)
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