| Abstract: Mass and angular momentum are fundamental drivers of galaxy formation and evolution. Global scaling relations between specific angular momentum (j) and mass (M) are well established for stars, gas, and baryons, each component exhibiting distinct trends. However, global relations average over entire galaxies, obscuring how angular momentum is distributed internally and how structural differences between components shape these relationships. In this talk, I will present new insights from the MHONGOOSE survey, an ultra-deep MeerKAT HI survey targeting 30 nearby galaxies spanning a broad range of masses. MHONGOOSE’s high spatial resolution and exceptional column-density sensitivity enable us to trace neutral hydrogen to large radii and faint surface densities. By deriving rotation curves with 3D tilted-ring modeling and measuring stellar surface-density profiles, we construct spatially resolved specific angular momentum–mass profiles for stars, gas, and baryons. Our results reveal systematic differences between components. Stars, characterized by steep exponential surface-density profiles, predominantly occupy low-angular-momentum regions in galaxy centers. In contrast, the extended HI gas distributions, often broader and more Gaussian-like, carry a significant portion of angular momentum at intermediate and large radii. These internal differences naturally explain the contrasting global j-M slopes observed for stars (~0.55) versus gas (~1). We further highlight individual galaxies that, despite aligning closely with global scaling relations, show significant internal deviations. These cases demonstrate the power of resolved angular momentum mapping as a sensitive diagnostic of recent gas accretion, interactions, and feedback-driven disturbances. |
