SIMBAD references

2017MNRAS.472..772M - Mon. Not. R. Astron. Soc., 472, 772-787 (2017/November-3)

Spectroscopic properties of luminous Ly α emitters at z ~= 6-7 and comparison to the Lyman-break population.


Abstract (from CDS):

We present spectroscopic follow-up of candidate luminous Ly α emitters (LAEs) at z = 5.7-6.6 in the SA22 field with VLT/X-SHOOTER. We confirm two new luminous LAEs at z = 5.676 (SR6) and z = 6.532 (VR7), and also present HST follow-up of both sources. These sources have luminosities L_Ly α_ ≃ 3 x 1043 erg s–1, very high rest-frame equivalent widths of EW0 >= 200 Å and narrow Ly α lines (200-340 km s–1). VR7 is the most UV-luminous LAE at z > 6.5, with M1500 = -22.5, even brighter in the UV than CR7. Besides Ly α, we do not detect any other rest-frame UV lines in the spectra of SR6 and VR7, and argue that rest-frame UV lines are easier to observe in bright galaxies with low Ly α equivalent widths. We confirm that Ly α line widths increase with Ly α luminosity at z = 5.7, while there are indications that Ly α lines of faint LAEs become broader at z = 6.6, potentially due to reionization. We find a large spread of up to 3 dex in UV luminosity for >L* LAEs, but find that the Ly α luminosity of the brightest LAEs is strongly related to UV luminosity at z = 6.6. Under basic assumptions, we find that several LAEs at z ≃ 6-7 have Ly α escape fractions >= 100 per cent, indicating bursty star formation histories, alternative Ly α production mechanisms, or dust attenuating Ly α emission differently than UV emission. Finally, we present a method to compute ξion, the production efficiency of ionizing photons, and find that LAEs at z ≃ 6-7 have high values of log10ion/Hz erg–1) ≃ 25.51 ± 0.09 that may alleviate the need for high Lyman-Continuum escape fractions required for reionization.

Abstract Copyright: © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): galaxies: evolution - galaxies: high-redshift - dark ages, reionization, first stars - cosmology: observations

VizieR on-line data: <Available at CDS (J/MNRAS/472/772): tableb1.dat tableb2.dat>

Nomenclature: Figs 1-3, Table 1: [MSD2017] SR6 N=1, [MSD2017] VR7 N=1. Table B1: [MSD2017] COSMOS-NB816-NNNNNN N=192 among (Nos 136-463732), [MSD2017] SA22-NB816-NNNNNN N=142 among (Nos 9442-569714), [MSD2017] UDS-NB816-NNNNNN N=151 among (Nos 31-148211). Table B2: [MSD2017] COSMOS-NB921-NNNNNN N=14 among (Nos 5032-130525), [MSD2017] UDS-NB921-NNNNNN N=97 among (Nos 1122-275877).

Simbad objects: 48

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