Far-infrared observations of dust in Lyα emitters at <i>z</i> ≈ 2 – 6

Abstract The bright Lyα line is regularly used to identify high-redshift star-forming galaxies known as Lyα emitters (LAEs). However, Lyα is affected by resonant scattering and dust absorption making interpretation of its brightness challenging without additional observations. We use SCUBA-2, PACS and SPIRE data to investigate the far-infrared emission, Lyα escape fraction (fesc(Lyα)) and infrared excess (IRX = LIR/LUV) in ~4000 LAEs at z ≈ 2.2 – 6 from SC4K. Five LAEs, all hosting AGN, are individually detected with fluxes S850 = 3.7 – 5.5 mJy at 850 $\rm \mu$m. Stacking is used to probe the average emission from all individually-undetected LAEs, though the stacks are undetected at all wavelengths (e.g. S850 &amp;lt; 0.09 mJy; 3σ). We group the sample into bins of redshift, stellar mass, Lyα luminosity and AGN status. Most subsets are undetected but LAEs containing AGN and that have high stellar masses (M* = 1010 − 12 M⊙; including and excluding AGN) are detected at most wavelengths, suggesting that stellar mass and AGN heating may be enhancing the dust visibility. Individually detected LAEs and detected stacks have fesc(Lyα) = 1–7%, while all undetected stacks ≳ 10%. All LAEs together average over &amp;gt;21% and display significant scatter, suggesting a clumpy ISM dust distribution. Non-zero fesc(Lyα) in massive and AGN-hosting LAEs suggests ionizing photons may escape even from dusty galaxies, challenging the idea that dusty galaxies are poor leakers. Examination of the IRX-βUV relation shows LAEs have higher IRX than typical star-forming galaxies at similar redshifts. However, our detections tend to favour more massive, AGN-hosting systems and deeper observations are therefore needed.