Abstract
The flow of baryons to and from a galaxy, which is fundamental for galaxy formation and evolution, can be studied with galaxy-metal absorption system pairs. Our search for galaxies around CIV absorption systems at $z\sim5.7$ showed an excess of photometric Lyman-$\alpha$ emitter (LAE) candidates in the fields J1030+0524 and J1137+3549. Here we present spectroscopic follow-up of 33 LAEs in both fields. In the first field, three out of the five LAEs within 10$h^{{-}1}$ projected comoving Mpc from the CIV system are within $\pm500$ km s$^{{-}1}$ from the absorption at $z_{\text{CIV}}=5.7242\pm0.0001$. The closest candidate (LAE 103027+052419) is robustly confirmed at $212.8^{+14}_{-0.4}h^{-1}$ physical kpc from the CIV system. In the second field, the LAE sample is selected at a lower redshift ($\Delta z\sim0.04$) than the CIV absorption system as a result of the filter transmission and, thus, do not trace its environment. The observed properties of LAE 103027+052419 indicate that it is near the high-mass end of the LAE distribution, probably having a large HI column density and large-scale outflows. Therefore, our results suggest that the CIV system is likely produced by a star-forming galaxy which has been injecting metals into the intergalactic medium since $z>6$. Thus, the CIV system is either produced by LAE 103027+052419, implying that outflows can enrich larger volumes at $z>6$ than at $z\sim3.5$, or an undetected dwarf galaxy. In either case, CIV systems like this one trace the ionized intergalactic medium at the end of cosmic hydrogen reionization and may trace the sources of the ionizing flux density.
Highlights
The detection of metal absorption systems depends on the ionization balance of the absorbing gas, we can learn about the galaxies that reionized the Universe through the Statistical studies of C iv absorption systems across cosmic time (e.g. Ryan-Weber et al 2009; Becker, Rauch & Sargent 2009; Simcoe et al 2011; D’Odorico et al 2013) suggest that some physical properties of the absorbing ‘clouds’, for example the size and the number density, are changing towards higher redshift
Following our findings of an excess of Lyman-α emitter (LAE) candidates in the projected environment of z ∼ 5.7 C iv absorption systems resported in Paper I, this work presents the results from the spectroscopic campaign using the deimos spectrograph on the Keck-II telescope for LAEs in the fields J1030+0524 and J1137+3549
We find that LAEs at z ∼ 5.7 are not recovered by the i -dropout criteria since most of them have (i − z ) < 1.3
Summary
The detection of metal absorption systems depends on the ionization balance of the absorbing gas, we can learn about the galaxies that reionized the Universe through the. It has been observed that C iv absorption systems with column densities NC iv> 1014 at z = 2–3 are related to the circumgalactic medium (CGM) of LBGs (Adelberger et al 2005; Steidel et al 2010) In these galaxies the red-shifted Lyα emission line and the blue-shifted interstellar absorption with respect to the systemic redshift determined by nebular emission lines (e.g. Hα, Hβ and O iii), is evidence for enriched gas moving at high velocities (hundreds of km s−1).
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