$\Lambda$CDM halo substructure properties revealed with high resolution and large volume cosmological simulations

Ángeles Moliné , Miguel A. Sánchez-Conde , Alejandra Aguirre-Santaella , Tomoaki Ishiyama , Francisco Prada , Sofía A. Cora , Darren Croton , Eric Jullo (1) , R. Benton Metcalf , Taira Oogi , José Ruedas

1 LAM - Laboratoire d'Astrophysique de Marseille

We investigate the structural properties, distribution and abundance of LCDM dark matter subhaloes using the Phi-4096 and Uchuu suite of N-body cosmological simulations. Thanks to the combination of their large volume, high mass resolution and superb statistics, we are able to quantify -- for the first time consistently over more than seven decades in ratio of subhalo-to-host-halo mass -- dependencies of subhalo properties with mass, maximum circular velocity, Vmax, host halo mass and distance to host halo centre. We also dissect the evolution of these dependencies over cosmic time. We provide accurate fits for the subhalo mass and velocity functions, both exhibiting decreasing power-law slopes in the expected range of values and with no significant dependence on redshift. We also find subhalo abundance to depend weakly on host halo mass. We explore the distribution of subhaloes within their hosts and its evolution over cosmic time for subhaloes located as deep as ~0.1 per cent of the host virial radius. Subhalo structural properties are codified via a concentration parameter, cV, that does not depend on any specific, pre-defined density profile and relies only on Vmax. We derive the cV-Vmax relation in the range 7-1500 km/s and find an important dependence on distance of the subhalo to the host halo centre, as already described in Moliné et al. (2017). Interestingly, we also find subhaloes of the same mass to be significantly more concentrated into more massive hosts. Finally, we investigate the redshift evolution of cV, and provide accurate fits that take into account all mentioned dependencies. Our results offer an unprecedented detailed characterization of the subhalo population, consistent over a wide range of subhalo and host halo masses, as well as cosmic times. Our work enables precision work in any future research involving dark matter halo substructure.

Mots clés: halo: mass; dark matter: halo; redshift; velocity; structure; slope; statistics; mass resolution; density; many-body problem; resolution; cosmological model; galaxy: halo; numerical methods

Domaines: Astrophysique [astro-ph]; Physique des Hautes Energies - Phénoménologie [hep-ph]

Ángeles Moliné, Miguel A. Sánchez-Conde, Alejandra Aguirre-Santaella, Tomoaki Ishiyama, Francisco Prada, et al.. $\Lambda$CDM halo substructure properties revealed with high resolution and large volume cosmological simulations. Monthly Notices of the Royal Astronomical Society, 2023, 518 (1), pp.157-173. ⟨10.1093/mnras/stac2930⟩. ⟨hal-03394445⟩