Physical Properties of Lyα Emitters at z ~ 0.3 from UV-to-FIR Measurements
The analysis of the physical properties of low-redshift Lyα
emitters (LAEs) can provide clues in the study of their high-redshift
analogs. At z ~ 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 ~ 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 ~ 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 Lyα emission in their spectrum (non-LAEs).
These results suggest that at z ~ 0.3, Lyα 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 ~ 0.3. Furthermore, the comparison of our results with
those obtained at higher redshifts indicates either that the Lyα
technique picks up different kind of galaxies at different redshifts or
that the physical properties of LAEs are evolving with redshift.