Luminosity functions of Lyman-alpha emitters at z = 6.5, and z = 5.7: Evidence against reionization at z = 6

Jul, 2004
Published in:
  • Astrophys.J.Lett. 617 (2004) L5-L8
e-Print:

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Abstract: (arXiv)
Lyman-alpha emission from galaxies should be suppressed completely or partially at redshifts beyond reionization. Without knowing the instrinsic properties of galaxies at z = 6.5, this attenuation is hard to infer in any one source, but can be infered from a comparison of luminosity functions of lyman-alpha emitters at redshifts just before and after reionization. We combine published surveys of widely varying depths and areas to construct luminosity functions at z=6.5 and 5.7, where the characteristic luminosity L_star and density phi_star are well constrained while the faint-end slope of the luminosity function is essentially unconstrained. Excellent consistency is seen in all but one published result. We then calculate the likelihood of obtaining the z=6.5 observations given the z=5.7 luminosity function with (A) no evolution and (B) an attenuation of a factor of three. Hypothesis (A) gives an acceptable likelihood while (B) does not. This indicates that the z=6.5 lyman-alpha lines are not strongly suppressed by a neutral intergalactic medium and that reionization was largely complete at z = 6.5.
  • galaxies: evolution
  • galaxies: formation
  • galaxies: high-redshift
  • galaxies: luminosity function, mass function
  • intergalactic medium
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