The AIDA-TNG project: abundance, radial distribution, and clustering properties of halos in alternative dark matter models

TL;DR

This study uses dark matter–only runs from the aida-TNG project to quantify how warm dark matter (WDM) and self-interacting dark matter (SIDM) alter halo abundance, radial subhalo distributions, and clustering, employing the halo occupation distribution (HOD) framework to extract $M_1$ and $\alpha$ across mass and redshift. By separating centrals and satellites and fitting generalized NFW profiles for subhalos, the authors show WDM induces cuspier satellite distributions while SIDM yields shallower cores; these changes propagate into the one-halo term of the two-point correlation function, enabling discrimination between DM models, especially at high redshift. The results highlight the complementarity of halo counts, radial profiles, and clustering in constraining DM physics, and they emphasize the need for high-resolution, full-physics simulations to account for baryonic effects when comparing with observations. The work demonstrates that small-scale clustering is a sensitive probe of the dark sector and sets the stage for baryon-inclusive studies that can be contrasted with galaxy clustering data.

Abstract

Warm and self-interactive dark matter cosmologies have been proposed as non-baryonic solutions to the tensions between the $Λ$ Cold Dark Matter model and observations at the kpc scale. In this paper, we use the dark matter-only runs of the \textsc{aida-tng} project, a set of cosmological simulations of different sizes and resolutions, to analyze the macroscopic impact of alternative dark matter models on the abundance, the radial distribution and the clustering properties of halos. We adopt the halo occupation distribution formalism to characterize the evolution of its parameters $M_1$ and $α$ with the mass and redshift selection of our sample. By dividing the halo population into central and satellites, we are able to study their spatial density profile, finding that a Navarro-Frenk-White model is not accurate enough to describe the radial distribution of subhalos, and that a generalized Navarro-Frenk-White model is required instead. Warm dark matter models, in particular, present a cuspier distribution of satellites, whereas self-interacting dark matter exhibits a shallower density profile. Moreover, we find that the small-scale clustering of dark matter halos provides a powerful tool to discriminate between alternative dark matter scenarios, in preparation for a more detailed study that fully incorporates baryonic effects, and for a comparison with observational data from galaxy clustering.

Figures (8)

• Figure 1: From top to bottom: spatial distribution of dark matter halos in the box 50/B, for CDM, WDM3 and WDM1 cosmologies. The colorbar shows the corresponding redshift in the range $0<z<2$.
• Figure 2: From left to right: different contributions to the two-point correlation function, from $z=0$ to $z=2$. The blue circles represent the measurement for the box 50/A, for CDM cosmology, considering halos with $M>10^8$ M$_\odot \, h^{-1}$. The corresponding errors are obtained with the jackknife method. The one-halo term is given by the purple, dotted line and it is the sum of $\xi_{cs}$ (solid orange line) and $\xi_{ss}$ (solid yellow line). The linear two-halo term (cyan dashed line) is then corrected for integral constraint, nonlinearities and halo exclusion (red dashed line). Finally, the solid, black line represents the total, best-fit model.
• Figure 3: From left to right: average number of dark matter pairs (top panels), halo occupation function (middle panels) and residuals (bottom panels) with respect to the CDM reference level (blue, solid line), in the box 50/A, in the range $0<z<2$, for CDM (blue circles), WDM3 (black triangles), WDM5 (crimson diamonds), SIDM1 (gold pentagons) and vSIDM (green triangles). The corresponding errors are computed with the standard deviation of the measurements, for each mass bin. The gray dashed, horizontal line represents the expected ratio for a Poissonian distribution. The gray solid, horizontal line signs the central halo, that always exists for $M_{200c}>M_\mathrm{min}$.
• Figure 4: Posterior distributions of the halo occupation function, $\langle N_h \rangle$, for different dark matter cosmologies (left panel), mass selections (middle panel) and redshifts (right panel). Different dark matter models are tested in the box 50/B, with a mass selection of $M_\mathrm{min}>10^9$ M$_\odot \,h^{-1}$. The other two panels consider the CDM cosmology in the box 50/A.
• Figure 5: From left to right: radial distribution of dark matter subhalos, at $z=0$, for various mass bins and dark matter models. The triangles represent bins with a group mass of $\log[{M_{200c}}/({\mathrm{M}_\odot h^{-1}})]=10.7$ (green), $11.6$ (gray), $12.6$ (gold), and $13.1$ (red), respectively. The solid, colored lines reflect the gNFW best-fit model. The corresponding errors are computed with the standard deviation of the measurements, for each mass bin.