The Effect of a Spiral Density Wave on the Galaxy’s Rotation Curve, as Applied to the Andromeda Galaxy (M31)

The rotational velocity curve, which is the circular profile of stars and gas in a spiral galaxy as function their distance from galactic center, plays an important role kinematic dynamic investigation galaxies. There are observations approximately flat rotation curves (RC) at large distances that have introduced mass discrepancy between theoretically derived RC observed one. In this paper, we derive expression using nonlinear density wave solution for surface (SMD) within disk. We show proposed able to support curve with no deficiency. aim paper confirm crucial importance distribution on profile. Although model limited by fluid description disk, it provides improved outer part disk due inclusion distribution. has not been averaged exponential approximation, but rather follows pattern given analytical equation. M31 chosen closest well mapped galaxy, similar many aspects our host order apply accounts effects RC. obtained result can strong influence large-scale gravity dynamics, well.