PACS-Herschel FIR detections of Lyman-alpha emitters at 2.0<z<3.5

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In this work we analyze the physical properties of a sample of 56 spectroscopically selected star-forming (SF) Lyα emitting galaxies at 2.03.5 using both a spectral energy distribution (SED) fitting procedure from rest-frame UV to mid-IR and direct 160μm observations taken with the Photodetector Array Camera & Spectrometer (PACS) instrument onboard Herschel Space Observatory. We define LAEs as those Lyα emitting galaxies whose rest-frame Lyα equivalent widths (Lyα EWrest-frame) are above 20Å, the typical threshold in narrow-band searches. Lyα emitting galaxies with Lyα EWrest-frame are called non-LAEs. As a result of an individual SED fitting for each object, we find that the studied sample of LAEs contains galaxies with ages mostly below 100Myr and a wide variety of dust attenuations, SFRs, and stellar masses. The heterogeneity in the physical properties is also seen in the morphology, ranging from bulge-like galaxies to highly clumpy systems. In this way, we find that LAEs at 2.03.5 are very diverse, and do not have a bimodal nature, as suggested in previous works. Furthermore, the main difference between LAEs and non-LAEs is their dust attenuation, because LAEs are not as dusty as non-LAEs. On the FIR side, four galaxies of the sample (two LAEs and two non-LAEs) have PACS-FIR counterparts. Their total IR luminosity place all of them in the ULIRG regime and are all dusty objects, with A₁₂₀₀4mag. This is an indication from direct FIR measurements that dust and Lyα emission are not mutually exclusive. This population of red and dusty LAEs is not seen at z 0.3, suggesting an evolution with redshift of the IR nature of galaxies selected via their Lyα emission.