Bright and Faint Ends of Ly$\alpha$ Luminosity Functions at $\text{z}=2$ Determined by the Subaru Survey: Implications for AGN, Magnification Bias, and ISM HI Evolution

Abstract

We present the Lya luminosity functions (LFs) derived by our deep Subaru narrowband survey that identifies a total of 3,137 Lya emitters (LAEs) at $z=2.2$ in five independent blank fields. The sample of these LAEs is the largest, to date, and covers a very wide Lya luminosity range of $\log L_{Ly\alpha }=41.7-44.4$ erg s${}^{-1}$. We determine the Lya LF at $z=2.2$ with unprecedented accuracies, and obtain the best-fit Schechter parameters of $L_{Ly\alpha }^{\ast }=5.29_{-1.13}^{+1.67}\times 10^{42}$ erg s${}^{-1}$, ${\varphi }_{Ly\alpha }^{\ast }=6.32_{-2.31}^{+3.08}\times 10^{-4}$ Mpc${}^{-3}$, and $\alpha =-1.75_{-0.09}^{+0.10}$ showing a steep faint-end slope. We identify a significant hump at the LF bright end ($\log L_{Ly\alpha }>43.4$ erg s${}^{-1}$). Because all of the LAEs in the bright-end hump have (a) bright counterpart(s) either in the X-ray, UV, or radio data, this bright-end hump is not made by gravitational lensing magnification bias but AGNs. These AGNs allow us to derive the AGN UV LF at $z\sim 2$ down to the faint magnitude limit of $M_{UV}\simeq -22.5$, and to constrain the faint-end slope of AGN UV LF, ${\alpha }_{AGN}=-1.2\pm 0.1$, that is flatter than those at $z>4$. Based on the Lya and UV LFs from our and previous studies, we find the increase of Lya escape fraction $f_{esc}^{Ly\alpha }$ from $z\sim 0$ to $6$ by two orders of magnitude. This large $f_{esc}^{Ly\alpha }$ increase can be explained neither by the evolution of stellar population nor outflow alone, but the evolution of neutral hydrogen HI density in inter-stellar medium that enhances dust attenuation for Lya by resonance scattering. Our uniform expanding shell models suggest that the typical HI column density decreases from $N_{HI}\sim 7\times 10^{19}$ ($z\sim 0$) to $\sim 1\times 10^{18}$ cm${}^{-2}$ ($z\sim 6$) to explain the large $f_{esc}^{Ly\alpha }$ increase.

18 pages, 10 figures, 5 tables, Accepted for publication in The Astrophysical Journal

References in corpus (36)

• The Cosmic Evolution Survey (COSMOS) -- Overview
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• 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
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• Subaru Deep Survey V. A Census of Lyman Break Galaxies at z=4 and 5 in the Subaru Deep Fields: Photometric Properties
• The Chandra COSMOS Survey, I: Overview and Point Source Catalog
• The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field
• Ly-alpha Emission-Line Galaxies at z = 3.1 in the Extended Chandra Deep Field South
• Faint AGNs at z>4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe
• The VLA-COSMOS Survey: II. Source Catalog of the Large Project
• The Subaru/XMM-Newton Deep Survey (SXDS) - II. Optical Imaging and Photometric Catalogs
• A galaxy at a redshift z = 6.96
• Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium
• The Multiwavelength Survey by Yale-Chile (MUSYC): Deep Medium-Band optical imaging and high quality 32-band photometric redshifts in the ECDF-S
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• Radio imaging of the Subaru/XMM-Newton Deep Field - I. The 100-microJy catalogue, optical identifications, and the nature of the faint radio source population
• Spectroscopic detections of CIII]1909 at z~6-7: A new probe of early star forming galaxies and cosmic reionisation
• The Subaru/XMM-Newton Deep Survey (SXDS): III. X-Ray Data
• The Ly-alpha Properties of Faint Galaxies at z2-3 with Systemic Redshifts and Velocity Dispersions from Keck-MOSFIRE
• Identification of the brightest Lyα emitters at z=6.6: implications for the evolution of the luminosity function in the re-ionisation era
• Deep U band and R imaging of GOODS-South: Observations,data reduction and first results
• Accelerated Evolution of Ly$\alpha$ Luminosity Function at $\text{z}\gtrsim 7$ Revealed by the Subaru Ultra-Deep Survey for Ly$\alpha$ Emitters at $\text{z}=7.3$
• The Evolution of the UV Luminosity Function from z ~ 0.75 to z ~ 2.5 using HST ERS WFC3/UVIS Observations
• The VIMOS Ultra-Deep Survey (VUDS): fast increase of the fraction of strong Lyman alpha emitters from z=2 to z=6
• A Luminosity Function of Lyman Alpha Emitting Galaxies at Redshift 4.5
• Lyman Alpha Emitters at Redshift 5.7 in the COSMOS Field
• The CALYMHA survey: Ly$\alpha$ escape fraction and its dependence on galaxy properties at $z=2.23$
• Lyman alpha emitting galaxies at 0.2 < z < 0.35 from GALEX spectroscopy
• Correcting the z~8 Galaxy Luminosity Function for Gravitational Lensing Magnification Bias
• Escape fraction of ionizing photons from galaxies at z=0--6
• Physical properties of z~4 LBGs: differences between galaxies with and without Ly-alpha emission
• A Spectroscopic Survey of Faint Quasars in the SDSS Deep Stripe: I. Preliminary Results from the Co-added Catalog
• The Lyman Alpha Reference Sample: III. Properties of the Neutral ISM from GBT and VLA Observations
• Connecting Faint End Slopes of the Lyman-$\alpha$ emitter and Lyman-break Galaxy Luminosity Functions
• HST Emission Line Galaxies at z ~ 2: The Ly-alpha Escape Fraction
• First Infrared-based implications for the dust attenuation and star formation of typical Ly$\alpha$ emitters

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