Physical properties of Lyman-alpha emitters at $z\sim 0.3$ from UV-to-FIR measurements

TL;DR

This study investigates the physical properties of low-redshift Ly$ extalpha$ emitters (LAEs) at $z\,sim\,0.3$ using UV-to-FIR data, revealing they are less dusty, smaller, and have higher SFRs compared to non-LAEs, with implications for galaxy evolution.

Contribution

It provides a comprehensive multi-wavelength analysis of $z\, extasciitilde\,0.3$ LAEs, highlighting differences in dust, size, and morphology compared to non-LAEs, and discusses potential evolutionary trends.

Findings

LAEs are less dusty and have higher SFRs than non-LAEs.

LAEs tend to be smaller and have irregular or merging morphologies.

The properties of LAEs may evolve with redshift or depend on selection techniques.

Abstract

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.