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Nao Sakai

Publications and source records attributed to Nao Sakai.

2 recordsLinked to original sources

The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) Survey Design, Reductions, and Detections

We describe the survey design, calibration, commissioning, and emission-line detection algorithms for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). The goal of HETDEX is to measure the redshifts of over a million Ly$α$ emitting galaxies between 1.88<z<3.52, in a 540 deg^2 area encompassing a co-moving volume of 10.9 Gpc^3. No pre-selection of targets is involved; instead the HETDEX measurements are accomplished via a spectroscopic survey using a suite of wide-field integral field units distributed over the focal plane of the telescope. This survey measures the Hubble expansion parameter and angular diameter distance, with a final expected accuracy of better than 1%. We detail the project's observational strategy, reduction pipeline, source detection, and catalog generation, and present initial results for science verification in the COSMOS, Extended Groth Strip, and GOODS-N fields. We demonstrate that our data reach the required specifications in throughput, astrometric accuracy, flux limit, and object detection, with the end products being a catalog of emission-line sources, their object classifications, and flux-calibrated spectra.

astro-ph.IM

First HETDEX Spectroscopic Determinations of Ly$α$ and UV Luminosity Functions at $z=2-3$: Bridging a Gap Between Faint AGN and Bright Galaxies

We present Ly$α$ and ultraviolet-continuum (UV) luminosity functions (LFs) of galaxies and active galactic nuclei (AGN) at $z=2.0-3.5$ determined by the un-targetted optical spectroscopic survey of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). We combine deep Subaru imaging with HETDEX spectra resulting in $11.4$ deg$^2$ of fiber-spectra sky coverage, obtaining $18320$ galaxies spectroscopically identified with Ly$α$ emission, $2126$ of which host type 1 AGN showing broad (FWHM$~>1000$ km s$^{-1}$) Ly$α$ emission lines. We derive the Ly$α$ (UV) LF over 2 orders of magnitude covering bright galaxies and AGN in $\log L_\mathrm{Lyα}/\mathrm{[erg~s^{-1}]}=43.3-45.5$ ($-27 -21$) type 1 AGN increases from $z\sim2$ to $z\sim0$ as opposed to the evolution of bright ($M_\mathrm{UV}<-21$) type 1 AGN, suggesting the AGN downsizing in the rest-frame UV luminosity.

astro-ph.GA