Variations of Hubble’s Parameter Across Galaxy Clusters

Over the years, there has been a dispute over the exact value of Hubble’s constant and the factors that cause variance. Through our research, we intend to answer the question, “To what extent does cluster density impact the calculated Hubble parameter and lead to variations in the value?” We hypothesized that higher galaxy cluster densities (i.e., the estimated number of galaxies within a cluster) would correspond to smaller values of Hubble’s constant due to local gravitational interactions between galaxies. We selected approximately twenty galaxies each from sixteen galaxy clusters of varying distances. Using the NASA/IPAC Extragalactic Database (NED), SIMBAD, and the A catalog of rich clusters of galaxies, we compiled data on recessional velocities, distances, and densities. We then used Hubble’s law to derive each galaxy’s Hubble constant, which allowed us to calculate its range for each cluster and average the Hubble parameters to get the overall constant for each cluster. We used linear regression models to visualize the relationship between each galaxy’s distance from Earth and its recessional velocity, with the slope of the line of best fit providing us with an estimate for Hubble’s constant. We concluded that the correlations between densities and H range, densities and H average, distance and H range, and Hubble parameter and cluster density are all weak to moderately correlated, with p-values of 0.4841, 0.3916, 0.0778, and 0.03, respectively.