We present a new photometric search for high- z galaxies hosting Population III ( PopIII ) stars based on deep intermediate-band imaging observations obtained in the Subaru Deep Field ( SDF ) , by using Suprime-Cam on the Subaru Telescope .
By combining our new data with the existing broad-band and narrow-band data , we searched for galaxies which emit strongly both in Ly \alpha and in He ii \lambda 1640 ( “ dual emitters ” ) that are promising candidates for PopIII-hosting galaxies , at 3.93 \lesssim z \lesssim 4.01 and 4.57 \lesssim z \lesssim 4.65 .
Although we found 10 “ dual emitters ” , most of them turn out to be [ O ii ] - [ O iii ] dual emitters or H \beta - ( H \alpha + [ N ii ] ) dual emitters at z < 1 , as inferred from their broad-band colors and from the ratio of the equivalent widths .
No convincing candidate of Ly \alpha -He ii dual emitter of SFR _ { PopIII } \gtrsim 2 M _ { \odot } yr ^ { -1 } was found by our photometric search in 4.03 \times 10 ^ { 5 } Mpc ^ { 3 } in the SDF .
This result disfavors low feedback models for PopIII star clusters , and implies an upper-limit of the PopIII SFR density of SFRD _ { PopIII } < 5 \times 10 ^ { -6 } M _ { \odot } yr ^ { -1 } Mpc ^ { -3 } .
This new selection method to search for PopIII-hosting galaxies should be useful in future narrow-band surveys to achieve the first observational detection of PopIII-hosting galaxies at high redshifts .