FIR Measurements of Lyα Emitters at z <~ 1.0: Dust Attenuation from PACS-Herschel
One remaining open question regarding the physical properties of
Lyα emitters (LAEs) is their dust content and evolution with
redshift. The variety of results is large and with those reported by now
it is difficult to establish clear relations between dust, other
fundamental parameters of galaxies (star formation rate, metallicity, or
age), and redshift. In this Letter, we report Herschel PACS-100 μm,
PACS-160 μm, and Spitzer MIPS-24 μm detections of a sample of
spectroscopically GALEX selected LAEs at z ~ 0.3 and ~ 1.0. Five out of
ten and one out of two LAEs are detected in, at least, one PACS band at
z ~ 0.3 and ~ 1.0, respectively. These measurements have a great
importance given that they allow us to quantify, for the first time, the
dust content in LAEs from direct FIR observations. MIPS-24 μm
detections allow us to determine the IR properties of the
PACS-undetected LAEs. We obtain that mid-IR/FIR-detected star-forming
(SF) LAEs at z ~ 0.3 have dust content within 0.75 <~ A <SUB>1200
Å</SUB> <~ 2.0, with a median value of A <SUB>1200
Å</SUB> ~ 1.1. This range broadens up to 0.75 <~ A <SUB>1200
Å</SUB> <~ 2.5 when considering the LAEs at z ~ 1.0. Only one
SF LAE is undetected both in MIPS-24 μm and PACS, with A <SUB>1200
Å</SUB> <~ 0.75. These results seem to be larger than those
reported for high-redshift LAEs and, therefore, although an evolutionary
trend is not clearly seen, it could point out that low-redshift LAEs are
dustier than high-redshift ones. However, the diverse methods used could
introduce a systematic offset in the results.