Abstract
We present a sample of $1000$ emission line galaxies at $z=0.4-4.7$ from
the $\sim0.7$deg$^2$ High-$z$ Emission Line Survey (HiZELS) in the Boötes
field identified with a suite of six narrow-band filters at $0.4-2.1$
$\mu$m. These galaxies have been selected on their Ly$\alpha$ (73), OII
(285), H$\beta$/OIII (387) or H$\alpha$ (362) emission-line, and have been
classified with multi-wavelength photometry, multiple narrow-band (e.g.
OII-H$\alpha$) detections and spectroscopy. In this paper, we present the
observations, selection and catalogs of emitters, the general properties of the
sample and the first results. We derive luminosity functions (LFs) for
Ly$\alpha$, OII, H$\beta$/OIII and H$\alpha$ and confirm a strong
luminosity evolution from $z\sim0.4$ to $5$, in good agreement with
previous results obtained in other fields like COSMOS and UDS. We explore the
properties of dual line-emitters, most notably OII-H$\alpha$ at $z=1.47$. The
observed OII/H$\alpha$ ratio increases from 0.40$\pm0.01$ at $z=0.1$ to
0.52$\pm0.05$ at $z=1.47$, which we attribute to either decreasing dust
attenuation with redshift, or due to fiber-measurements in the local Universe
which only measure the central kpc regions. At the bright end, we find that
both the H$\alpha$ and Ly$\alpha$ LFs at $z\approx2.2$ deviate significantly
from a Schechter form, becoming a power-law. We show that this is fully driven
by an increasing X-ray/AGN fraction with line-luminosity, reaching $\approx
100$ % at line-luminosities $\gtrsim3\times10^44$ erg s$^-1$.
Description
[1702.04721] Bo\"otes-HiZELS: an optical to near-infrared survey of emission-line galaxies at $\bf z=0.4-4.7$
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