A Spectroscopic Survey of Ly$\alpha$ Emitters at $z\approx 3.1$ over $\sim$1.2 Deg${}^2$

Abstract

We present a spectroscopic survey of Ly$\alpha$ emitters (LAEs) at $z\approx 3.1$ in the Subaru MM-Newton Deep Survey Field. This field has deep imaging data in a series of broad and narrow bands, including two adjacent narrow bands NB497 and NB503 that have allowed us to efficiently select LAE candidates at $z\approx 3.1$. Using spectroscopic observations on MMT Hectospec and Magellan M2FS, we obtained a sample of 166 LAEs at $z\approx 3.1$ over an effective area of $\sim$1.2 deg${}^2$, including 16 previously known LAEs. This is so far the largest (spectroscopically confirmed) sample of LAEs at this redshift. We make use of the secure redshifts and multi-band data to measure spectral properties such as Ly$\alpha$ luminosity and rest-frame UV slope. We derive a robust Ly$\alpha$ luminosity function (LF) that spans a luminosity range from $\sim 10^{42.0}$ to $>10^{43.5}$ erg s${}^{-1}$. Significant overdense and underdense regions are detected in our sample, but the area coverage is wide enough to largely suppress the effect from such cosmic variance. Our Ly$\alpha$ LF is generally consistent with those from previous studies at $z\sim 3.1$. At the brightest end of the LF, there is a tentative detection of a density excess that is not well described by the Schechter function. The comparison with the LFs at other redshifts suggests that the Ly$\alpha$ LF does not show significant evolution at $2<z<5$. Finally, we build the composite spectra of the LAEs and detect the NVI and CIV doublet emission lines at significance of $\sim 4\sigma$, suggesting very hard radiation fields in (some of) these LAEs.

17 pages, 16 figures, accepted for publication in ApJ

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• MUSE Analysis of Gas around Galaxies (MAGG) -- III: The gas and galaxy environment of z = 3-4.5 quasars
• The Magellan M2FS Spectroscopic Survey of High-Redshift Galaxies: A Sample of 260 Ly$\alpha$ Emitters at Redshift $z\approx 5.7$
• Median Surface Brightness Profiles of Lyman-$\alpha$ Haloes in the MUSE Extremely Deep Field
• Probing the faint end Luminosity Function of Lyman Alpha Emitters at 3<z<7 behind 17 MUSE lensing clusters
• Spatially-resolved Spectroscopic Analysis of Ly$\alpha$ Haloes: Radial Evolution of the Ly$\alpha$ Line Profile out to 60 kpc
• Lyman Alpha line properties at $z\simeq 3.78$ and their environmental dependence: a case study around a massive proto-cluster