Zhen-Ya Zheng, Steven L. Finkelstein, Keely Finkelstein, Vithal Tilvi, James E. Rhoads, Sangeeta Malhotra, Jun-Xian Wang, Neal Miller, Pascale Hibon, Lifang Xia
We present a spectroscopically confirmed Lyman alpha emitter sample at z ~
4.5 in the Extended Chandra Deep Field South region. Starting with spectra of
68 candidate Ly-\alpha\ emitters, we identified 46 z ~ 4.5 Ly-\alpha emitters
based on single-line detections with no continuum emission blueward of the
line, and 5 Lyman break galaxies. The Ly-\alpha\ confirmation rate is ~ 70% for
candidates selected in our two narrowband filters, and the remaining candidates
including 5 Lyman Break Galaxies and one strange multi emission line object. We
did not find any significant CIV emission line or HeII emission line in the
optical spectra even with the coadded optical spectra. A majority of the LAEs
show asymmetric Ly-\alpha\ line profile, and the coadded Ly-\alpha\ line has
wavelength-based asymmetry of a_\lambda\ = 1.49$^{+0.26}_{-0.13}$ and
flux-based asymmetry of a_f = 1.45$^{+0.06}_{-0.07}$. Deep X-ray, radio and the
optical spectral data are also used to constrain the AGN contribution in our
sample, only one detection (not targeted in spectroscopic observation) was
found at z=4.5 in both X-ray and radio, while the other objects show
non-detection even with a stacking method. Finally, the Ly-\alpha\ luminosity
function for our z ~ 4.5 sample is consistent with others published in the
literature for the redshift range of 3 < z < 6, while the Ly-\alpha\ luminosity
functions in our two separate narrowband filters show a ~ 2\sigma\ difference.
This difference is comparable to the differences among z = 5.7 and z = 6.5
Ly-\alpha\ luminosity functions reported by Ouchi et al. (2010), which are
thought to be an implication of cosmic re-ionization.
View original:
http://arxiv.org/abs/1111.3386
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