アブストラクト：
We report a tentative detection of the Lyα sources around galaxies at ~20-300 physical kpc (pkpc) at z=5.7 and 6.6 based on the intensity mapping analysis of the cross correlation between Lyα emitters (LAEs) position and Lyα surface brightness. We use ultra-deep narrowband images that are taken with Subaru HSC, and derive the cross-correlation function with the large samples of LAEs obtained by the HSC SILVERRUSH program. These cross-correlation signals reside at the extremely large scale up to ~300 pkpc that is about an order of magnitude larger than diffuse Lyα haloes (LAHs) around high-z star-forming galaxies. So far, we find no sources of systematics that are large enough to mimic the cross-correlation signals.