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On the nature of Hα emitters at z∼2 from the HiZELS survey: physical properties, Lyα escape fraction, and main sequence

I. Oteo, D. Sobral, R. J. Ivison, I. Smail, P. Best, J. Cepa, A. M. Pérez-García

We present a detailed multi-wavelength study (from rest-frame UV to far-IR) of narrow-band (NB) selected, star-forming (SF) Hα emitters (HAEs) at z2.23 taken from the High Redshift(Z) Emission Line Survey (HiZELS). We find that HAEs have similar SED-derived properties and colors to sBzK galaxies and probe a well-defined portion of the SF population at z2 . This is not true for Lyα emitters (LAEs), which are strongly biased towards blue, less massive galaxies (missing a significant percentage of the SF population). Combining our Hα observations with matched, existing Lyα data we determine that the Lyα escape fraction (fesc ) is low (only 4.5\% of HAEs show Lyα emission) and decreases with increasing dust attenuation, UV continuum slope, stellar mass, and star formation rate (SFR). This suggests that Lyα preferentially escapes from blue galaxies with low dust attenuation. However, a small population of red and massive LAEs is also present in agreement with previous works. This indicates that dust and Lyα are not mutually exclusive. Using different and completely independent measures of the total SFR we show that the Hα emission is an excellent tracer of star formation at z2 with deviations typically lower than 0.3 dex for individual galaxies. We find that the slope and zero-point of the HAE main-sequence (MS) at z2 strongly depend on the dust correction method used to recover SFR, although they are consistent with previous works when similar assumptions are made.

galaxies: evolution - galaxies: high-redshift - galaxies: star formation

Monthly Notices of the Royal Astronomical Society
Volume 452, Issue 2, Page 2018
2015 September

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia