Properties of Subhalos in the Interacting Dark Matter Scenario

Abstract

One possible and natural derivation from the collisionless cold dark matter (CDM) standard cosmological framework is the assumption of the existence of interactions between dark matter (DM) and photons or neutrinos. Such possible interacting dark matter (IDM) model would imply a suppression of small-scale structures due to a large collisional damping effect, even though the weakly interacting massive particle (WIMP) can still be the DM candidate. Because of this, IDM models can help alleviate alleged tensions between standard CDM predictions and observations at small mass scales. In this work, we investigate the properties of DM halo substructure or subhalos formed in a high-resolution cosmological N-body simulation specifically run within these alternative models. We also run its CDM counterpart, which allowed us to compare subhalo properties in both cosmologies. We show that, in the lower mass range covered by our simulation runs, both subhalo concentrations and abundances are systematically lower in IDM compared to the CDM scenario. Yet, as in CDM, we find that median IDM subhalo concentration values increase towards the innermost regions of their hosts for same mass subhalos. Also similarly to CDM, we find IDM subhalos to be more concentrated than field halos of the same mass. Our work has a direct application on studies aimed at the indirect detection of DM where subhalos are expected to boost the DM signal of their host halos significantly. From our results, we conclude that the role of halo substructure in DM searches will be less important in interacting scenarios than in CDM but far from being negligible.

Constraints on dark matter-neutrino scattering from the Milky-Way satellites and subhalo modeling for dark acoustic oscillations

“…Some details of precision of the simulations in refs. [17,25] are also lower than in the simulations in the case JCAP11(2023)037 of ETHOS models [70]. Thus, since the simulations in refs.…”

“…We should note that there are also some results of N-body simulations for the DM-photon interaction scenarios [17,25]. In ref.…”

“…In ref. [25], the authors compute the number of subhalos as a function of subhalo mass in the large mass bin of (0.3-1.4) × 10 12 M /h. Some details of precision of the simulations in refs.…”

“…Interactions of DM beyond gravity with the Standard Model (SM) (i.e., photons [16][17][18][19][20][21][22][23][24][25], neutrinos [23,[26][27][28][29][30][31][32][33][34][35][36] or baryons [19,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53]) or dark radiation [54][55][56][57][58][59][60][61][62][63][64][65]…”

Impact of substructure on local dark matter searches

“…We have focused in this work on the sub-halo distribution for standard Cold Dark Matter. Our approach could equally well be applied to other DM candidates, such as Warm Dark Matter [116] and Self-interacting Dark Matter [117,118], as well as DM with more exotic clustering properties [36,37]. We have also focused on direct searches for WIMP DM, though our framework may also be applied to axion searches, where axions are expected to form bound 'mini-clusters' [119], potentially giving an enhancement to the local density.…”