Ly$\alpha$ Emission from [OIII] Emitters Near Reionization: The role of environment in galaxy Ly$\alpha$ detection

Abstract

Using galaxy Ly$\alpha$ emission to probe reionization relies on establishing baseline expectations for its detectability in the absence of attenuation by neutral gas in the IGM. Towards this end, the growing numbers of $z\sim 5$--6 star-forming galaxies spectroscopically selected by JWST provide an ideal sample for determining how Ly$\alpha$ emission depends on galaxy properties and environment after reionization has largely completed. In this study, we use Keck LRIS to measure the Ly$\alpha$ emission of 46 JWST-selected [OIII]-emitting galaxies over $5.3\lesssim z\lesssim 6.2$ in the foreground of the ultra-luminous quasar J0100+2802. Overall, we find that the fraction of galaxies detected in Ly$\alpha$ emission is consistent with previous works; however, the fraction also varies with environment. Most notably, we find an apparent deficit of Ly$\alpha$ in the largest group in our sample, at $z\simeq 6.19$, which falls within the redshift range of the quasar's highly ionized proximity zone. We speculate that the Ly$\alpha$ emission from this group may be partly scattered by a foreground neutral island. In contrast, we detect a high rate of Ly$\alpha$ emission in two groups at $z\simeq 5.73$ and $z\simeq 5.78$. These groups may be part of a structure that is extended along the line of sight, enhancing the transmission of Ly$\alpha$ emission. While our sample size is limited, our results suggest that environment may play a significant role in the detectability of galaxy Ly$\alpha$ emission even as late as $z\sim 6$.

15 pages, 12 figures, Accepted for publication in MNRAS

References in corpus (19)

• Array Programming with NumPy
• A luminous quasar at a redshift of z = 7.085
• Model-independent evidence in favor of an end to reionization by z~6
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• Pōniuā'ena: A Luminous $z=7.5$ Quasar Hosting a 1.5 Billion Solar Mass Black Hole
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium
• New observations of z~7 galaxies: evidence for a patchy reionization
• Inferences on the Timeline of Reionization at z~8 From the KMOS Lens-Amplified Spectroscopic Survey
• A Significantly Neutral Intergalactic Medium Around the Luminous z=7 Quasar J0252-0503
• The Ly-alpha Properties of Faint Galaxies at z2-3 with Systemic Redshifts and Velocity Dispersions from Keck-MOSFIRE
• Star formation and the interstellar medium in z>6 UV-luminous Lyman-break galaxies
• The VIMOS Ultra-Deep Survey (VUDS): fast increase of the fraction of strong Lyman alpha emitters from z=2 to z=6
• IGM damping wing constraints on reionisation from covariance reconstruction of two $z\gtrsim 7$ QSOs
• SpectRes: A Fast Spectral Resampling Tool in Python
• A VLT/FORS2 view at $z\sim 6$: Lyman-$\alpha$ emitter fraction and galaxy physical properties at the edge of the epoch of cosmic reionization
• Damping Wing-Like Features in the Stacked Ly$\alpha$ Forest: Potential Neutral Hydrogen Islands at $z<6$
• A massive, neutral gas reservoir permeating a galaxy proto-cluster after the reionization era
• A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE): JWST Supports Earlier Reionization around [OIII] Emitters