Connecting Faint End Slopes of the Lyman-$\alpha$ emitter and Lyman-break Galaxy Luminosity Functions

Abstract

We predict Lyman-$\alpha$ (Ly$\alpha$) luminosity functions (LFs) of Ly$\alpha$-selected galaxies (Ly$\alpha$ emitters, or LAEs) at $z=3-6$ using the phenomenological model of Dijkstra & Wyithe (2012). This model combines observed UV-LFs of Lyman-break galaxies (LBGs, or drop out galaxies), with constraints on their distribution of Ly$\alpha$ line strengths as a function of UV-luminosity and redshift. Our analysis shows that while Ly$\alpha$ LFs of LAEs are generally not Schechter functions, these provide a good description over the luminosity range of ${\log }_{10}(L_{\alpha }/\mathrm{erg}{\mathrm{s}}^{-1})=41-44$. Motivated by this result, we predict Schechter function parameters at $z=3-6$. Our analysis further shows that (i) the faint end slope of the Ly$\alpha$ LF is steeper than that of the UV-LF of Lyman-break galaxies, (with a median ${\alpha }_{Ly\alpha }<-2.0$ at $z\gtrsim 4$), and (ii) a turn-over in the Ly$\alpha$ LF of LAEs at Ly$\alpha$ luminosities $10^{40}$ erg s${}^{-1}<L_{\alpha }\lesssim 10^{41}$ erg s${}^{-1}$ may signal a flattening of UV-LF of Lyman-break galaxies at $-12>M_{\mathrm{UV}}>-14$. We discuss the implications of these results - which can be tested directly with upcoming surveys - for the Epoch of Reionization.

8 pages, 6 figures, submitted to MNRAS (after revision following referee's report)

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Cited by in corpus (13)

• Identification of the brightest Lyα emitters at z=6.6: implications for the evolution of the luminosity function in the re-ionisation era
• Measuring the properties of reionised bubbles with resolved Lyman alpha spectra
• The Evolution of the Lyman-Alpha Luminosity Function During Reionization
• Confirmation of a Steep Luminosity Function for Lyman-alpha Emitters at z = 5.7: A Major Component of Reionization
• J-PLUS: Unveiling the brightest-end of the Lyα luminosity function at 2.0<z<3.3 over 1000 deg^2
• First HETDEX Spectroscopic Determinations of Ly$\alpha$ and UV Luminosity Functions at $z=2-3$: Bridging a Gap Between Faint AGN and Bright Galaxies
• Lyman continuum leakage in faint star-forming galaxies at redshift z=3-3.5 probed by gamma-ray bursts
• The spin-temperature dependence of the 21cm -- LAE cross-correlation
• The THESAN project: Lyman-alpha emitter luminosity function calibration
• Can galaxy evolution mimic cosmic reionization?
• SIMPLE: Simple Intensity Map Producer for Line Emission
• Galaxy populations in protoclusters at cosmic noon
• ODIN: Using multiplicity of Lyman-Alpha Emitters to assess star formation activity in dark matter halos