(Proposal ID) S16A-110

(PI) Matsuda, Yuichi

(Proposal Title)
Lyalpha intensity mapping around the bright QSO at z=2.84

(Abstract)
We propose deep HSC Lyalpha imaging of one of the bright QSOs, SDSS J155152.46+
191104.0 at z=2.842 with a custom narrow-band filter, NB468. Recently, Croft 
et al.(2015) discovered large-scale (r ~ 15 comoving Mpc/h) clustering of 
Lyalpha emission intensity around SDSS/BOSS QSOs at 2<z<3.5.  This discovery 
gave us an interesting implication for our understanding of galaxy formation 
and evolution.  If the dominant sources of the diffuse Lyalpha emission are 
star-forming galaxies, the inferred total mean star formation rate density 
(SFRD) is a factor of ~ 30 above previous estimates from individually detected 
Lyalpha emitters, although it is consistent with the total SFRD derived from 
dust-corrected, continuum UV surveys. This proposal aims to confirm this 
important discovery and test if the dominant sources of the large-scale 
diffuse Lyalpha emission are star-forming galaxies or the QSOs themselves. 
We will be able to detect the large-scale Lyalpha emission at the 10-sigma 
level with reasonable amount of observing time (2 dark-grey nights), if the 
previous Lyalpha intensity measurement is correct.