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We present results of sub-arcsec ALMA observations of CO(2-1) and CO(5-4)toward a massive main sequence galaxy at z = 1.45 in the SXDS/UDS field, aimingat examining the internal distribution and properties of molecular gas in thegalaxy. Our target galaxy consists of the bulge and disk, and has a UV clump inthe HST images. The CO emission lines are clearly detected and theCO(5-4)/CO(2-1) flux ratio (R_52) is ~1, similar to that of the Milky Way.Assuming a metallicity dependent CO-toH_2 conversion factor and aCO(2-1)/CO(1-0) flux ratio of 2 (the Milky Way value), the molecular gas massand the gas mass fraction (f_gas = molecular gas mass / (molecular gas mass +stellar mass)) are estimated to be ~1.5x10^11 M_Sun and ~0.55, respectively. Wefind that R_52 peak coincides with the position of the UV clump and its valueis approximately two times higher than the galactic average. This resultimplies high gas density and/or high temperature in the UV clump, whichqualitatively agrees with a numerical simulation of a clumpy galaxy. TheCO(2-1) distribution is well represented by a rotating disk model and itshalf-light radius is ~2.3 kpc. Compared to the stellar distribution, themolecular gas is more concentrated in the central region of the galaxy. We alsofind that f_gas decreases from ~0.6 at the galactic center to ~0.2 at3xhalf-light radius, indicating that the molecular gas is distributed in morecentral region of the galaxy than stars and seems to associate with the bulgerather than the stellar disk.

Internal structure of molecular gas in a main sequence galaxy with a UV clump at z = 1.45