PACS-Herschel FIR detections of Lyman-alpha emitters at 2.0<z<3.5
In this work we analyze the physical properties of a sample of 56
spectroscopically selected star-forming (SF) Ly$\alpha$ emitting
galaxies at 2.0$\lesssim$z$\lesssim$3.5 using both a spectral energy
distribution (SED) fitting procedure from rest-frame UV to mid-IR and
direct 160$\mu$m observations taken with the Photodetector Array Camera
& Spectrometer (PACS) instrument onboard \emph{Herschel Space
Observatory}. We define LAEs as those Ly$\alpha$ emitting galaxies whose
rest-frame Ly$\alpha$ equivalent widths (Ly$\alpha$ EW$$)
are above 20\AA, the typical threshold in narrow-band searches.
Ly$\alpha$ emitting galaxies with Ly$\alpha$ EW$_{rest-frame}$ are
called non-LAEs. As a result of an individual SED fitting for each
object, we find that the studied sample of LAEs contains galaxies with
ages mostly below 100Myr and a wide variety of dust attenuations, SFRs,
and stellar masses. The heterogeneity in the physical properties is also
seen in the morphology, ranging from bulge-like galaxies to highly
clumpy systems. In this way, we find that LAEs at
2.0$\lesssim$z$\lesssim$3.5 are very diverse, and do not have a bimodal
nature, as suggested in previous works. Furthermore, the main difference
between LAEs and non-LAEs is their dust attenuation, because LAEs are
not as dusty as non-LAEs. On the FIR side, four galaxies of the sample
(two LAEs and two non-LAEs) have PACS-FIR counterparts. Their total IR
luminosity place all of them in the ULIRG regime and are all dusty
objects, with A${1200}$$\gtrsim$4mag. This is an indication from direct
FIR measurements that dust and Ly$\alpha$ emission are not mutually
exclusive. This population of red and dusty LAEs is not seen at
z$\sim$0.3, suggesting an evolution with redshift of the IR nature of
galaxies selected via their Ly$\alpha$ emission.