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Michi Shinozaki

Publications and source records attributed to Michi Shinozaki.

2 recordsLinked to original sources
arXiv2026

The Characteristic Mass and Energy Conversion Efficiency in the Cusp-Core Transition of Dark Matter Haloes: Implications for Scaling Relations and Supernova feedbacks

Galaxies in the nearby Universe, particularly dwarf systems, exhibit inner mass profiles of dark matter haloes that systematically depart from canonical cold dark matter expectations, signalling an interplay between baryonic feedback and the collisionless halo. We update an analytical cusp-core transition model by incorporating the effect of supernova-driven mass loss. Adapting this model to SPARC galaxies, we measure the energy conversion efficiency epsilon, defined as the fraction of supernova feedback energy that is used to change the central dark-matter potential. We find epsilon ~ 0.01 for nearby SPARC galaxies. Building on these measurements, we compare the dynamical energy required for a cusp-core transformation with the feedback energy available over burst cycles and identify a cusp-core transition forbidden region on the halo-stellar mass plane where transformation cannot occur. Galaxies with halo masses from 10^8 to 10^11 M_sun lie outside the forbidden region, whereas ultra-faint dwarf galaxies < 10^8 M_sun, galaxy groups and clusters > 10^11 M_sun fall within it, consistent with their high central densities and the inefficiency of core formation at very low and very high masses. This approach also explains the observed diversity of inner density profiles in low-mass systems, showing that both the star formation rate and the energy conversion efficiency govern them, with the latter emerging as a key parameter setting the strength of the cusp-core transition. Beyond the cusp-core problem, our observationally inferred energy conversion efficiency provides a model independent benchmark that strongly constrains galaxy formation models.

astro-ph.GA↗
arXiv2026

Cusp-to-Core Transition of Dark Matter Halos across Galaxy Mass Scales

We investigate the diversity of dark matter (DM) density profiles in a large sample of late-type galaxies from the SPARC database, with the goal of testing whether a cusp-to-core transition occurs across galaxy mass scales. We perform Bayesian fits to high-quality rotation curves using flexible halo models that allow for variations in the inner slopes of DM density profiles. We quantify the central dark matter structure using the surface density within the inner region of the halo, defined as $Σ_{\rm DM}(<0.01r_{V_{\rm max}})$, and compare the SPARC galaxies with Milky Way dwarf satellites as well as galaxy groups and clusters. Our results reveal significant diversity in the inner density slopes of SPARC galaxies, ranging from steep cusps to shallow cores, and show that many of them lie below the cuspy profiles predicted by the cold dark matter model, consistent with core-like structures. In contrast, both lower-mass dwarf galaxies and higher-mass galaxy clusters tend to follow the cuspy DM halos. These findings suggest that baryonic feedback may induce a cusp-to-core transition in Milky Way-mass galaxies, as predicted by hydrodynamical simulations. However, observational limitations and modeling uncertainties still prevent a definitive conclusion. This study provides new empirical insights into the halo mass-dependent nature of DM inner structures and the role of baryonic processes in shaping them.

astro-ph.GA↗