Yung-Chau Su(NTU/ASIAA); Li-Hwai Lin(ASIAA);Hsi-An Pan(MPIA);Bau-Ching Hsieh(ASIAA)
In this study, we compare the CO(J=1-0) and Ha kinematics in nearby galaxies. We investigate 17 rotation-dominated, late-type galaxies selected from the ALMaQUEST survey, which is the combination of ALMA CO(J=1-0) Observations for 46 galaxies selected from the MaNGA IFS sample. We use 3-D Barolo, a 3D tilted ring model, to derive the CO and Ha rotation curves. Our result shows that 65%(11/17) of galaxies among the ALMaQUEST subsample present lower Ha rotation compared to the CO rotation, while the remaining galaxies show consistent CO-Ha rotations. To compare with previous research, we also analyze 17 rotation-dominated, star-forming galaxies from the EDGE-CALIFA survey. By combining these data, Our preliminary result suggests that the existence of non-negligible radial pressure support to ionized gas could explain the systematic velocity discrepancy between CO and Ha rotation. On the other hand, there is tentative evidence suggesting that extraplanar diffuse ionized gas, which has lower rotation velocity, also plays a role in the CO-Ha velocity discrepancy.