The evolution of rest-frame UV properties, Lya EWs and the SFR-Stellar mass relation at z~2-6 for SC4K LAEs

Abstract

We explore deep rest-frame UV to FIR data in the COSMOS field to measure the individual spectral energy distributions (SED) of the ~4000 SC4K (Sobral et al. 2018) Lyman-alpha (Lya) emitters (LAEs) at z~2-6. We find typical stellar masses of 10${}^{9.3\pm 0.6}$ M${}_{\odot }$ and star formation rates (SFR) of SFR${}_{SED}=4.4_{-2.4}^{+10.5}$ M${}_{\odot }$/yr and SFR${}_{Lya}=5.9_{-2.6}^{+6.3}$ M${}_{\odot }$/yr, combined with very blue UV slopes of beta=-2.1${}_{-0.4}^{+0.5}$, but with significant variations within the population. M${}_{UV}$ and beta are correlated in a similar way to UV-selected sources, but LAEs are consistently bluer. This suggests that LAEs are the youngest and/or most dust-poor subset of the UV-selected population. We also study the Lya rest-frame equivalent width (EW${}_0$) and find 45 "extreme" LAEs with EW${}_0>240$ A (3 $\sigma$), implying a low number density of $(7\pm 1)\times 10^{-7}$ Mpc${}^{-3}$. Overall, we measure little to no evolution of the Lya EW${}_0$ and scale length parameter ($w_0$) which are consistently high (EW${}_0=140_{-70}^{+280}$ A, $w_0=129_{-11}^{+11}$ A) from z~6 to z~2 and below. However, $w_0$ is anti-correlated with M${}_{UV}$ and stellar mass. Our results imply that sources selected as LAEs have a high Lya escape fraction (f${}_{esc,Lya}$) irrespective of cosmic time, but f${}_{esc,Lya}$ is still higher for UV-fainter and lower mass LAEs. The least massive LAEs ($<10^{9.5}$ M${}_{\odot }$) are typically located above the star formation "Main Sequence" (MS), but the offset from the MS decreases towards z~6 and towards $10^{10}$ M${}_{\odot }$. Our results imply a lack of evolution in the properties of LAEs across time and reveals the increasing overlap in properties of LAEs and UV-continuum selected galaxies as typical star-forming galaxies at high redshift effectively become LAEs.

Accepted for publication in MNRAS. 23 pages, 11 figures, 3 tables + appendices. The full SC4K catalogue of LAEs with PSF photometry, stellar masses, SFRs and other properties for individual LAEs, is available at https://goo.gl/q9yfKo

References in corpus (37)

• The Cosmic Evolution Survey (COSMOS) -- Overview
• Star Formation in AEGIS Field Galaxies since z=1.1 : The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-Forming Galaxies
• A simple model to interpret the ultraviolet, optical and infrared emission from galaxies
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• COSMOS Photometric Redshifts with 30-bands for 2-deg2
• Constraining the Low-Mass Slope of the Star Formation Sequence at 0.5<z<2.5
• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• UltraVISTA: a new ultra-deep near-infrared survey in COSMOS
• An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
• 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
• An ALMA survey of Sub-millimeter Galaxies in the Extended Chandra Deep Field South: Physical properties derived from ultraviolet-to-radio modelling
• Distant Radio Galaxies and their Environments
• The Cosmic Evolution Survey (COSMOS): Subaru Observations of the HST COSMOS Field
• The VIMOS Ultra-Deep Survey: ~10,000 galaxies with spectroscopic redshifts to study galaxy assembly at early epochs 2<z<~6
• Ly-alpha Emission-Line Galaxies at z = 3.1 in the Extended Chandra Deep Field South
• The Relation Between SFR and Stellar Mass for Galaxies at 3.5 $\le z\le$ 6.5 in CANDELS
• The VLA-COSMOS Survey: II. Source Catalog of the Large Project
• Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium
• A Population of Faint Extended Line Emitters and the Host Galaxies of Optically Thick QSO Absorption Systems
• The MUSE 3D view of the Hubble Deep Field South
• The Visible and Infrared Survey Telescope for Astronomy (VISTA): Design, Technical Overview and Performance
• Star Formation at $4<z<6$ From the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH)
• The Constant Average Relationship between Dust-obscured Star Formation and Stellar Mass from $z=0$ to $z=2.5$
• Identification of the brightest Lyα emitters at z=6.6: implications for the evolution of the luminosity function in the re-ionisation era
• Diffuse Lyman-alpha Halos around Galaxies at z=2.2-6.6: Implications for Galaxy Formation and Cosmic Reionization
• Mid-IR Luminosities and UV/Optical Star Formation Rates at z<1.4
• The VLA-COSMOS Survey: III. Further Catalog Analysis and the Radio Source Counts
• The VIMOS Ultra-Deep Survey (VUDS): fast increase of the fraction of strong Lyman alpha emitters from z=2 to z=6
• The CALYMHA survey: Lya luminosity function and global escape fraction of Lya photons at z=2.23
• The MUSE Hubble Ultra Deep Field Survey VI: The Faint-End of the Lya Luminosity Function at 2.91 < z < 6.64 and Implications for Reionisation
• Dissecting the IRX - $\beta$ dust attenuation relation: exploring the physical origin of observed variations in galaxies
• Spectroscopic properties of luminous Lyman-α emitters at $z\approx 6-7$ and comparison to the Lyman-break population
• The MUSE Hubble Ultra Deep Field Survey X. Ly$\alpha$ Equivalent Widths at $2.9<z<6.6$
• A Comprehensive Study of Ly$\alpha$ Emission in the High-redshift Galaxy Population
• The Stellar Mass, Star Formation Rate and Dark Matter Halo Properties of LAEs at $z\sim 2$
• A Faint Flux-Limited Lyman Alpha Emitter Sample at $z\sim 0.3$
• Similarities and uniqueness of Ly$\alpha$ emitters among star-forming galaxies at z=2.5

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