Statistical properties of diffuse Lyα haloes around star-forming galaxies at<i>z</i>∼ 2

Abstract

We present statistical properties of diffuse Ly haloes (LAHs) around high-z star-forming galaxies with large Subaru samples of Ly emitters (LAEs) at z = 2.2. We make subsamples defined by the physical quantities of LAEs' central Ly luminosities, ultraviolet (UV) magnitudes, Ly 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 luminosities, bright UV luminosities, and small Ly equivalent widths in cumulative radial Ly SB profiles. We confirm this trend with the anticorrelation between r n and Ly luminosities (equivalent widths) based on the Spearman's rank correlation coefficient that is = -0.9 (-0.7) corresponding to the 96 per cent (93 per cent) 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 luminosities and small equivalent widths) possess more prominent LAHs. We investigate scenarios for the major physical origins of LAHs with our results. Because we find relatively small Ly equivalent widths up to 77 in LAHs that include LAEs' central components, these results suggest that the cold stream scenario is not preferred. There remain two possible scenarios of Ly scattering in circumgalactic medium and satellite galaxies that cannot be tested with our observational data.