(Proposal ID) S15A-031

(PI) Shimakawa, Rhythm

(Proposal Title)
 Search for Lyalpha blobs and identification of their energy sources

(Abstract)
Giant Lyalpha nebulae called as Lyalpha blobs (LABs) are known to be 
preferentially found in over-dense regions at z~2--3.  It indicates that LABs 
are hosted by massive halos (>10^{12} M_sun) which have large potential wells 
and high gas densities.  Their morphologies (spatial extent and roundness) may 
be related to the surrounding environment because of different conditions of 
inter-galactic medium. The dominant energy source of LABs have many 
possibilities including photoionization by UV sources, cooling radiation from 
inflowing gas, and shock heating by galactic winds.  And it is yet to be 
identified. We here propose deep narrow-band (NB) imaging of Lyalpha emission 
lines at the redshift interval of z=2.50--2.57.  The target field is unique 
since it contains an extremely dense protocluster ever known and its 
surrounding regions, which provides us a unique opportunity to investigate 
the effect of environment on the properties of LABs. We have already 
identified 40 spectroscopically confirmed members and their global kinematics. 
Moreover, we have been accumulating invaluable data-set for this protocluster 
such as spatially resolved Halpha maps (AO+NB imaging) and HST images 
(WFC3, ACS). With all these information put together, we will identify the 
origin of the LABs.