A Lyman Alpha Galaxy at Redshift z=6.944 in the COSMOS Field

Abstract

Lyman-alpha emitting galaxies can be used to study cosmological reionization, because a neutral intergalactic medium scatters Lyman-alpha photons into diffuse halos whose surface brightness falls below typical survey detection limits. Here we present the Lyman-alpha emitting galaxy LAE J095950.99+021219.1, identified at redshift z=6.944 in the COSMOS field using narrowband imaging and followup spectroscopy with the IMACS instrument on the Magellan I Baade telescope. With a single object spectroscopically confirmed so far, our survey remains consistent with a wide range of IGM neutral fraction at redshift seven, but further observations are planned and will help clarify the situation. Meantime, the object we present here is only the third Lyman-alpha selected galaxy to be spectroscopically confirmed at redshift seven, and is 2--3 times fainter than the previously confirmed redshift seven Lyman alpha galaxies.

15 pages including 3 figures. Accepted for publication in The Astrophysical Journal Letters

References in corpus (1)

• A Luminosity Function of Lyman Alpha Emitting Galaxies at Redshift 4.5

Cited by in corpus (22)

• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Ly$\alpha$ emission from Green Peas: the role of circumgalactic gas density, covering, and kinematics
• Rapid Decline of Lyman-alpha Emission Toward the Reionization Era
• First Results from the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) Survey: Cosmological Reionization at z ~ 7
• Observational Searches for Galaxies at z > 6
• Onset of Cosmic Reionization: Evidence of An Ionized Bubble Merely 680 Myrs after the Big Bang
• Physical Properties of Spectroscopically-Confirmed Galaxies at z >= 6. I. Basic Characteristics of the Rest-Frame UV Continuum and Lyman-alpha emission
• The Magellan M2FS Spectroscopic Survey of High-$z$ Galaxies: Lyα Emitters at $z\approx 6.6$ and the Evolution of Lyα Luminosity Function over $z\approx 5.7-6.6$
• First Spectroscopic Confirmations of z ~ 7.0 Lya Emitting Galaxies in the LAGER Survey
• Search for [CII] emission in z=6.5-11 star-forming galaxies
• Connecting Faint End Slopes of the Lyman-$\alpha$ emitter and Lyman-break Galaxy Luminosity Functions
• Physical Properties of Spectroscopically-Confirmed Galaxies at $z\ge 6$. III. Stellar Populations from SED Modeling with Secure Ly$\alpha$ Emission and Redshifts
• Discovery of a z = 7.452 High Equivalent Width Lyman-α Emitter from the Hubble Space Telescope Faint Infrared Grism Survey
• Spectroscopic Confirmation of a z=6.740 Galaxy behind the Bullet Cluster
• Empirical Constraints on the Star Formation & Redshift Dependence of the Lyman Alpha `Effective' Escape Fraction
• A Magellan M2FS Spectroscopic Survey of Galaxies at 5.5<z<6.8: Program Overview and a Sample of the Brightest Lyman-alpha Emitters
• Constraining the Lyman Alpha Escape Fraction with Far-Infrared Observations of Lyman Alpha Emitters
• On-sky characterisation of the VISTA NB118 narrow-band filters at 1.19 micron
• The Magellan M2FS Spectroscopic Survey of High-Redshift Galaxies: A Sample of 260 Ly$\alpha$ Emitters at Redshift $z\approx 5.7$
• A Lyman Break Galaxy in the Epoch of Reionization from HST Grism Spectroscopy
• Deep LBT/LUCI Spectroscopy of a Lyman-alpha Emitter Candidate at z ~ 7.7
• Unlocking Sensitivity for Visibility-based Estimators of the 21 cm Reionization Power Spectrum