From Cluster Core to Splashback: Linking Dynamical Structure to Multidimensional Galaxy Evolution in the Coma Cluster
We investigate galaxy evolution across the full dynamical structure of the Coma cluster using the GalWCat19 spectroscopic cluster catalog combined with SDSS-based value-added galaxy properties. We measure a splashback radius of $R_{sp} = 2.94 \pm 0.16~h^{-1}\, Mpc$. Using specific star formation rate (sSFR), color offset from the red sequence ($Δ(g-r)_{RS}$), and bulge-to-total ratio ($B/T$) as independent diagnostics, we find a coherent environmental transition from quiescent, red, bulge-dominated galaxies in the cluster core to increasingly star-forming, blue, disk-dominated populations at larger radii. We further introduce a three-dimensional framework in the joint $(\log sSFR, Δ(g-r)_{RS}, B/T)$ space and develop a peak-based classification scheme that extends beyond traditional one-dimensional galaxy classifications. This framework identifies two dominant populations: red, quiescent, bulge-dominated galaxies, which account for $51\%$ of the joint-analysis sample, and blue, star-forming, disk-dominated galaxies, which account for $29\%$. The remaining $\sim20\%$ of galaxies occupy transitional or mixed states that connect these two principal populations. The relative fractions of these populations change strongly near the splashback radius, where the red, quiescent, bulge-dominated population declines rapidly and the blue, star-forming, disk-dominated population becomes increasingly dominant. These results show that the splashback boundary is not only a dynamical boundary, but also a critical evolutionary transition zone. Overall, our findings suggest that galaxy evolution in Coma is not a purely binary transformation, but instead proceeds through continuous multidimensional pathways in which star formation quenching, color evolution, and morphological transformation occur on different timescales while remaining closely linked to the cluster dynamical structure.