1110.1722 (E. Curtis-Lake et al.)

A remarkably high fraction of strong Ly_alpha emitters amongst luminous redshift 6.0    [PDF]

E. Curtis-Lake, R. J. McLure, H. J. Pearce, J. S. Dunlop, M. Cirasuolo, D. P. Stark, O. Almaini, E. J. Bradshaw, R. Chuter, S. Foucaud, W. G. Hartley

We present spectroscopic confirmation of ten highly luminous (L >= 2L*) Lyman alpha emitters in the redshift range 6.01= 6 Lyman break galaxies (LBGs) selected from an area of 0.25 square degrees within the UKIDSS Ultra-deep Survey (UDS). Overall, our high rate of spectroscopic confirmation (>= 71%) and low rate of contamination provides a strong vindication of the photometric redshift analysis used to define the original sample. By considering star-formation rate estimates based on the Ly_alpha and UV continuum luminosity we conclude that our sample is consistent with a Ly_alpha escape fraction of ~25%. Moreover, after careful consideration of the potential uncertainties and biases, we find that 40%-50% of our sample of L >= 2L* galaxies at 6.0= 25 Angs), a fraction which is a factor of ~2 higher than previously reported for L <= L* galaxies at z~6. Our results suggest that, as the epoch of reionization is approached, it is plausible that the Ly_alpha emitter fraction amongst luminous (L >=2 L*) LBGs shows a similarly sharp increase to that observed in their lower-luminosity (L <= L*) counterparts.

View original: http://arxiv.org/abs/1110.1722