2017MNRAS.468.1123S

We conducted a deep narrow-band imaging survey with the Subaru Prime Focus Camera on the Subaru Telescope and constructed a sample of Lyα emitters (LAEs) at z = 2.53 in the UDS-CANDELS field, where a sample of Hα emitters (HAEs) at the same redshift is already obtained from our previous narrow-band observation at near-infrared. The deep narrow-band and multibroad-band data allow us to find LAEs of stellar masses and star formation rates (SFRs) down to >=10⁸ M_☉ and >=0.2 M_☉ yr^–1, respectively. We show that the LAEs are located along the same mass-SFR sequence traced by normal star-forming galaxies such as HAEs, but towards a significantly lower mass regime. Likewise, LAEs seem to share the same mass-size relation with typical star-forming galaxies, except for the massive LAEs that tend to show significantly compact sizes. We identify a vigorous mass growth in the central part of LAEs: the stellar mass density in the central region of LAEs increases as their total galaxy mass grows. On the other hand, we see no Lyα line in emission for most of the HAEs. Rather, we find that the Lyα feature is either absent or in absorption (Lyα absorbers, LAAs), and its absorption strength may increase with reddening of the UV continuum slope. We demonstrate that a deep Lyα narrow-band imaging like this study is able to search for not only LAEs but also LAAs in a certain redshift slice. This work suggests that LAEs trace normal star-forming galaxies in the low-mass regime, while they remain as a unique population because the majority of HAEs are not LAEs.