We present statistical properties of diffuse Ly \alpha halos ( LAHs ) around high- z star-forming galaxies with large Subaru samples of Ly \alpha emitters ( LAEs ) at z = 2.2 .
We make subsamples defined by the physical quantities of LAEs ’ central Ly \alpha luminosities , UV magnitudes , Ly \alpha equivalent widths , and UV slopes , and investigate LAHs ’ radial surface brightness ( SB ) profiles and scale lengths r _ { n } as a function of these physical quantities .
We find that there exist prominent LAHs around LAEs with faint Ly \alpha luminosities , bright UV luminosities , and small Ly \alpha equivalent widths in cumulative radial Ly \alpha SB profiles .
We confirm this trend with the anti-correlation between r _ { n } and Ly \alpha luminosities ( equivalent widths ) based on the Spearman ’ s rank correlation coefficient that is \rho = -0.9 ( -0.7 ) corresponding to the 96 \% ( 93 \% ) confidence level , although the correlation between r _ { n } and UV magnitudes is not clearly found in the rank correlation coefficient .
Our results suggest that LAEs with properties similar to typical Lyman-break galaxies ( with faint Ly \alpha luminosities and small equivalent widths ) possess more prominent LAHs .
We investigate scenarios for the major physical origins of LAHs with our results , and find that the cold stream scenario is not preferred , due to the relatively small equivalent widths up to 77 Å in LAHs that include LAEs ’ central components .
There remain two possible scenarios of Ly \alpha scattering in circum-galactic medium and satellite galaxies that can not be tested with our observational data .