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 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 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 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.
Rana et al. (Thu,) studied this question.