Physical properties of Lyman-alpha emitters at $z\sim 0.3$ 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
analogues. At $z \sim 0.3$, 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
study, we examine the UV and IR emission, dust attenuation, SFR and
morphology of a sample of 23 GALEX-discovered star-forming (SF) LAEs at
$z \sim 0.3$ 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 $z\sim 0.3$ 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 $z \sim 0.3$ 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 $z \sim 0.3$. Furthermore, the comparison
of our results with those obtained at higher redshifts indicates that
either the Ly$\alpha$ technique picks up different kind of galaxies at
different redshifts or that the physical properties of LAEs are evolving
with redshift.