Herschel-PACS far-infrared detections of Lyman-α emitters at 2.0 ≲ z ≲ 3.5

Oteo, I.; Bongiovanni, A.; Pérez-García, A. M.; Cepa, J.; Ederoclite, A.; Sánchez-Portal, M.; Pintos-Castro, I.; Pérez-Martínez, R.; Berta, S.; Magnelli, B.; Popesso, P.; Pozzi, F.; Poglitsch, A.; Lutz, D.; Genzel, R.; Tacconi, L.; Förster Schreiber, N.; Sturm, E.; Elbaz, D.; Aussel, H.; Daddi, E.; Andreani, P.; Cimatti, A.; Maiolino, R.; Altieri, B.; Valtchanov, I.
Bibliographical reference

Astronomy and Astrophysics, Volume 541, id.A65

Advertised on:
5
2012
Number of authors
26
IAC number of authors
6
Citations
25
Refereed citations
24
Description
In this work we analyse the physical properties of a sample of 56 spectroscopically selected star-forming (SF) Lyα emitting galaxies at 2.0 ≲ z ≲ 3.5 using both a spectral energy distribution (SED) fitting procedure from rest-frame UV to mid-IR and direct 160 μm FIR observations taken with the Photodetector Array Camera and Spectrometer (PACS) instrument onboard the Herschel Space Observatory. We define LAEs as those Lyα-emitting galaxies whose rest-frame Lyα equivalent widths (Lyα EWrest - frame) are above 20 Å, the typical threshold in narrow-band searches. Lyα-emitting galaxies with Lyα EWrest - frame < 20 Å are called non-LAEs. As a result of an individual SED fit for each object, we find that the studied sample of LAEs contains galaxies with ages mostly below 100 Myr and a wide variety of dust attenuations, SFRs, and stellar masses. The heterogeneity of 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 ≲ z ≲ 3.5 are very diverse, and do not have a bimodal nature, as suggested in previous studies. 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 detections. Their total IR luminosities place all of them in the ULIRG regime, and all are dusty objects, with A1200 ≳ 4 mag. This is an indication from direct FIR measurements that dust and Lyα emission are not mutually exclusive. This population of red and dusty LAEs is not seen at z ~ 0.3, which suggests an evolution with redshift of the IR nature of galaxies selected via their Lyα emission. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix A is available in electronic form at http://www.aanda.org
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Evolution of Galaxies

Galaxy evolution is a crucial topic in modern extragalactic astrophysics, linking cosmology to the Local Universe. Their study requires collecting statistically significant samples of galaxies of different luminosities at different distances. It implies the ability to observe faint objects using different techniques, and at different wavelengths

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