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The angular momentum distribution (AMD), defined as the mass per unit specific angular momentum, encapsulates the full internal distribution of angular momentum in galaxies and dark matter haloes, going beyond what the total specific angular momentum alone can capture. Although dark matter haloes exhibit characteristic AMD profiles, how baryons acquire and redistribute their angular momentum during galaxy formation remains an open question. In this talk, I will present our recent observational study of the AMDs of baryonic components in nearby disc galaxies, using 3.6$\mu$m photometry and HI data from 105 disc galaxies in the SPARC survey. Our results reveal a diverse range of AMD profiles: While 66 galaxies exhibit a low-j deficit relative to the dark matter AMD, consistent with previous studies, the remaining 39 galaxies show baryonic AMDs that either closely follow the dark matter AMD or exhibit a low-j excess. This diversity correlates with galaxy properties and points to potentially different roles of feedback, gas accretion, and angular momentum redistribution across galaxy populations. Building on these observational findings, I will discuss our ongoing efforts to investigate the physical origins of this diversity using the COLIBRE cosmological simulations. Through this approach, we aim to establish a physical framework for interpreting the diversity of AMD profiles observed in disc galaxies.

Host: Dandan Xu