S22B0016
S22B0016
Gaseous processes play essential roles in regulating the formation of galaxies and groups/clusters especially in their early phases. However, we do not know well how the neutral gas is distributed in and around individual galaxies and along the large scale structures. Two new adjacent/overlapping narrow-band (NB) filters on HSC (NB391 and NB395) will provide us with a unique opportunity to map the 3D structures of Lyα emitters at z=2.23 in COSMOS where we already conducted a panoramic NB Hα imaging survey with WFCAM on UKIRT (HiZELS) and mapped 2D structures including a rich protocluster confirmed by follow-up spectroscopy. A map of the Lyα/Hα line ratios of galaxies in the structures to be obtained by the proposed NB imaging will trace the associated HI gas that depletes Lyα line from star forming galaxies by resonant scattering with respect to Hα. We will investigate the environmental dependence of the HI gas association to galaxies and groups/clusters and discuss if the cold-mode gas accretion in hot media can efficiently accumulate cold gas towards the intersections of filamentary structures (protoclustes) or if the enhanced star forming activities in protoclusters may ionize the surrounding gas which then becomes transparent for Lyα photons.
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