Star Formation in Nearby Disk Galaxies
I have been working on star formation activities (i.e. star formation rate, efficiency and Kennicutt-Schmidt law) in nearby galaxies using millimeter wavelength observations, paying special attention to galactic structures (the nuclei, bar, arm and inter-arms). I found that star formation activities are different depending on galactic structures at a barred galaxy, NGC 4303. To establish the universality of these difference in star formation activity as a function of galactic structures, I am verifying them in 10 nearby spiral galaxies. The results have been summarized in my Ph.D. thesis.
Galaxy Formation and Evolution Traced by Lyman-alpha Emitters
I am also working on Lyman-alpha halos (LAHs) around Lyman-alpha emitters (LAEs). Based on large number of LAEs found by the Subaru telescope, LAHs have been detected at z = 2.2, 3.1, 5.7 and 6.6. I have measured scale lengths of LAHs assuming exponential profile. I have obtained scale lengths to be 5-10 kpc at 2.2 < z < 5.7, and found no evolution of scale lengths. However, I have found a possible increase of scale lengths from z = 5.7 to 6.6. This scale length change at z > 6 would be a signature of increasing fraction of neutral hydrogen scattering Lyman-alpha photons, due to cosmic reionization.
I am also working on Lyman-alpha halos (LAHs) around Lyman-alpha emitters (LAEs). Based on large number of LAEs found by the Subaru telescope, LAHs have been detected at z = 2.2, 3.1, 5.7 and 6.6. I have measured scale lengths of LAHs assuming exponential profile. I have obtained scale lengths to be 5-10 kpc at 2.2 < z < 5.7, and found no evolution of scale lengths. However, I have found a possible increase of scale lengths from z = 5.7 to 6.6. This scale length change at z > 6 would be a signature of increasing fraction of neutral hydrogen scattering Lyman-alpha photons, due to cosmic reionization.