Signatures of self-interacting dark matter on cluster density profile and subhalo distributions

Abstract

Non-gravitational interactions between dark matter particles with strong scattering, but relatively small annihilation and dissipation, has been proposed to match various observables on cluster and group scales. In this paper, we present the results from large cosmological simulations which include the effects of different self-interaction scenarios. In particular we explore a model with the differential cross section that can depend on both the relative velocity of the interacting particles and the angle of scattering. We focus on how quantities, such as the stacked density profiles, subhalo counts and the splashback radius change as a function of different forms of self-interaction. We find that self-interactions not only affect the central region of the cluster, the effect well known from previous studies, but also significantly alter the distribution of subhalos and the density of particles out to the splashback radius. Our results suggest that current weak lensing data can already put constraints on the self-interaction cross-section that are only slightly weaker than the Bullet Cluster constraints (σ/m 2 cm 2 /g), and future lensing surveys should be able to tighten them even further making halo profiles on cluster scales a competitive probe for DM physics.

N-body simulations of dark matter with frequent self-interactions

“…Correa 2021;Sagunski et al 2021) and have been investigated in several -body studies (e.g. Colin et al 2002;Vogelsberger et al 2012;Banerjee et al 2020). In fact such a velocity dependence is very natural from the particle physics perspective, in particular for frequent DM scatterings induced by lightmediator exchange, see e.g.…”

Cluster–galaxy weak lensing

“…The splashback radius is a genuine prediction of the standard CDM picture of structure formation. We can possibly learn something about the nature of dark matter and cosmology (Adhikari et al 2018;Banerjee et al 2020). Moreover, this steepening feature may be used to make the connection to the dynamical relaxation state of halos.…”

Reconciling galaxy cluster shapes, measured by theorists versus observers

“…As extreme peaks in the density field, clusters of galaxies are ideal laboratories to study dark matter (e.g. Harvey et al 2017b,a;Schwinn et al 2017Schwinn et al , 2018Banerjee et al 2020;Kahlhoefer et al 2014;Robertson et al 2019;Harvey et al 2019) and constrain cosmology (e.g. Kratochvil et al 2010;Marian et al 2011;Cardone et al 2013).…”