Measuring Rotation Curves of Spiral Galaxies with DESI Year 1

We analyze the rotation curves of spiral galaxies to quantify their dark matter component and better understand the impact it has on spiral galaxy dynamics. Previous observations show that the stellar mass alone cannot account for the gravitational effects seen in rotation curves, indicating the presence of large dark matter halos surrounding these galaxies. We calculate rotational velocities from spectra observed during the first year of the Dark Energy Spectroscopic Instrument (DESI) Peculiar Velocity Survey, and model the rotation curves of those spiral galaxies that pass visual inspection. Parameterizing the rotation curves allows us to estimate the total mass of the galaxies within R26 (the radius of the 26 mag/arcsec2 isophote). We find a strong correlation between this total mass and the galaxy's luminosity, which is to be expected from the Tully-Fisher relation and confirms the validity of our total mass calculations. Additionally, the relationship between total mass and stellar mass, as well as the ratios of gas to stellar mass and dark matter to stellar mass, provide insights into the distribution of dark matter within spiral galaxies, allowing us to better constrain the properties of dark matter.