Physical Properties of Lyα Emitters at z ~ 0.3 from UV-to-FIR Measurements

The analysis of the physical properties of low-redshift Ly alpha emitters (LAEs) can provide clues in the study of their high-redshift analogs. At z similar to 0.3, LAEs are bright enough to be detected over almost the entire electromagnetic spectrum and it is possible to carry out a more precise and complete study than at higher redshifts. In this work, we examine the UV and IR emission, dust attenuation, star formation rate (SFR), and morphology of a sample of 23 GALEX-discovered star-forming LAEs at z similar to 0.3 with direct UV (GALEX), optical (ACS), and FIR (PACS and MIPS) data. Using the same UV and IR limiting luminosities, we find that LAEs at z similar to 0.3 tend to be less dusty, have slightly higher total SFRs, have bluer UV continuum slopes, and are much smaller than other galaxies that do not exhibit Ly alpha emission in their spectrum (non-LAEs). These results suggest that at z similar to 0.3, Ly alpha photons tend to escape from small galaxies with low dust attenuation. Regarding their morphology, LAEs belong to Irr/merger classes, unlike non-LAEs. Size and morphology represent the most noticeable difference between LAEs and non-LAEs at z similar to 0.3. Furthermore, the comparison of our results with those obtained at higher redshifts indicates either that the Ly alpha technique picks up different kind of galaxies at different redshifts or that the physical properties of LAEs are evolving with redshift.