The Magellan M2FS Spectroscopic Survey of High-$z$ Galaxies: Lyα Emitters at $z\approx 6.6$ and the Evolution of Lyα Luminosity Function over $z\approx 5.7-6.6$

Abstract

We present a sample of Lyα emitters (LAEs) at $z\approx 6.6$ from our spectroscopic survey of high-redshift galaxies using the multi-object spectrograph M2FS on the Magellan Clay telescope. The sample consists of 36 LAEs selected by the narrow-band (NB921) technique over nearly 2 deg${}^2$ in the sky. These galaxies generally have high Lyα luminosities spanning a range of $\sim 3\times 10^{42}-7\times 10^{43}$ erg s${}^{-1}$, and include some of the most Lyα-luminous galaxies known at this redshift. They show a positive correlation between the Lyα line width and Lyα luminosity, similar to the relation previously found in $z\approx 5.7$ LAEs. Based on the spectroscopic sample, we calculate a sophisticated sample completeness correction and derive the Lyα luminosity function (LF) at $z\approx 6.6$. We detect a density bump at the bright end of the Lyα LF that is significantly above the best-fit Schechter function, suggesting that very luminous galaxies tend to reside in overdense regions that have formed large ionized bubbles around them. By comparing with the $z\approx 5.7$ Lyα LF, we confirm that there is a rapid LF evolution at the faint end, but a lack of evolution at the bright end. The fraction of the neutral hydrogen in the intergalactic medium at $z\approx 6.6$ estimated from such a rapid evolution is about $\sim 0.3\pm 0.1$, supporting a rapid and rather late process of cosmic reionization.

Accepted for publication in ApJ

References in corpus (23)

• Observational constraints on Cosmic Reionization
• The Subaru/XMM-Newton Deep Survey (SXDS). IV. Evolution of Lya Emitters from z=3.1 to 5.7 in the 1 deg^2 Field: Luminosity Functions and AGN
• New Determinations of the UV Luminosity Functions from z~9 to z~2 show a remarkable consistency with halo growth and a constant star formation efficiency
• The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field
• A galaxy at a redshift z = 6.96
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• New observations of z~7 galaxies: evidence for a patchy reionization
• Identification of the brightest Lyα emitters at z=6.6: implications for the evolution of the luminosity function in the re-ionisation era
• The mean free path of ionizing photons at 5 < z < 6: evidence for rapid evolution near reionization
• Luminosity Functions of Lyman Alpha Emitting Galaxies and Cosmic Reionization of Hydrogen
• The MUSE Hubble Ultra Deep Field Survey X. Ly$\alpha$ Equivalent Widths at $2.9<z<6.6$
• The X-SHOOTER Lyman-$\alpha$ survey at z=2 (XLS-z2) I: What makes a galaxy a Lyman-$\alpha$ emitter?
• The Diversity of Diffuse Ly$\alpha$ Nebulae around Star-Forming Galaxies at High Redshift
• The Predicament of Absorption-Dominated Reionization: Increased Demands on Ionizing Sources
• A High Space Density of Luminous Lyman Alpha Emitters at z~6.5
• Crucial Factors for Lyα Transmission in the Reionizing Intergalactic Medium: Infall Motion, HII Bubble Size, and Self-shielded Systems
• Lyman-Alpha Emitter Galaxies at z ~ 2.8 in the Extended Chandra Deep Field-South: I. Tracing the Large-Scale Structure via Lyman-Alpha Imaging
• The Ultraluminous Lyman Alpha Luminosity Function at z=6.6
• The Evolution of the Ultraluminous Ly-alpha Luminosity Function over z=5.7-6.6
• A Magellan M2FS Spectroscopic Survey of Galaxies at 5.5<z<6.8: Program Overview and a Sample of the Brightest Lyman-alpha Emitters
• The Magellan M2FS Spectroscopic Survey of High-Redshift Galaxies: A Sample of 260 Ly$\alpha$ Emitters at Redshift $z\approx 5.7$
• Luminous Lyman-alpha Emitters with Very Blue UV-continuum Slopes at Redshift 5.7 <= z <= 6.6
• Diffuse Lyman-alpha Halos around ~300 Spectroscopically Confirmed Lyman-alpha Emitters at z ~ 5.7

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