Probing the Disk Kinematics of M31 with DESI

M31’s stellar rotation curve and disk line-of-sight dispersion is presented using kinematic data from a novel DESI M31 survey in combination with similar datasets. After removing the foreground, the disk region is isolated and the velocity field deprojected. A flat ring model is fit to the velocity field of M31 out to 30 kpc using a maximum-likelihood routine. The stellar rotation curve is found to flatten to ∼220 km/s, and a disk line-of-sight velocity dispersion of ∼60 km/s is derived. The results extend M31’s rotation curve to 30 kpc and support the picture in which M31 has thicker disk than the Milky Way.