Better Distances from 21-cm Measurements of Galaxies

The Undergraduate ALFALFA Team's (UAT) main goal was to measure the dark matter present in galaxies within the Pisces Perseus Supercluster. To do that we needed to fix any inconsistencies present within UAT's initial galaxy measurements. Our project involved measuring emissions from neutral hydrogen (HI) in galaxies in the PPS using the Green Bank Radio Telescope, which detects radio emissions from space. These measurements allowed us to calculate the galaxies' recessional velocity (how fast they move away from us), rotation velocity, and mass. We then used these measurements to contribute to an improved measurement of the Baryonic Tully-Fisher Relations (BTFR), which is a relationship between the mass of regular (baryonic) matter in galaxies and how fast they are rotating. This allows us to use the rotation rates we measure to estimate the distances to galaxies. Based on our investigation, we potentially might have improved how these galaxies are portrayed on the BTFR plot as we can now determine how far the galaxies are from the PPS, and thus its gravitational tug on the individual galaxies. We hope to eventually contribute to the first-ever measurement of the total dark-matter mass in a galaxy supercluster.