Coherent Self-Interactions of Dark Matter in the Bullet Cluster

Fuente: arXiv
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Main Authors: Bogorad, Zachary, Graham, Peter W., Ramani, Harikrishnan
Format: Preprint
Published: 2023
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author Bogorad, Zachary
Graham, Peter W.
Ramani, Harikrishnan
author_facet Bogorad, Zachary
Graham, Peter W.
Ramani, Harikrishnan
contents Many models of dark matter include self-interactions beyond gravity. A variety of astrophysical observations have previously been used to place limits on the strength of such self-interactions. However, previous works have generally focused either on short-range interactions resulting in individual dark matter particles scattering from one another, or on effectively infinite-range interactions which sum over entire dark matter halos. In this work, we focus on the intermediate regime: forces with range much larger than dark matter particles' inter-particle spacing, but still shorter than the length scales of known halos. We show that gradients in the dark matter density of such halos would still lead to observable effects. We focus primarily on effects in the Bullet Cluster, where finite-range forces would lead either to a modification of the collision velocity of the cluster or to a separation of the dark matter and the galaxies of each cluster after the collision. We also consider constraints from the binding of ultrafaint dwarf galaxy halos, and from gravitational lensing of the Abell 370 cluster. Taken together, these observations allow us to set the strongest constraints on dark matter self-interactions over many orders of magnitude in range below $\sim10$ kpc, surpassing existing limits by orders of magnitude throughout.
format Preprint
id arxiv_https___arxiv_org_abs_2311_07648
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Coherent Self-Interactions of Dark Matter in the Bullet Cluster
Bogorad, Zachary
Graham, Peter W.
Ramani, Harikrishnan
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
Many models of dark matter include self-interactions beyond gravity. A variety of astrophysical observations have previously been used to place limits on the strength of such self-interactions. However, previous works have generally focused either on short-range interactions resulting in individual dark matter particles scattering from one another, or on effectively infinite-range interactions which sum over entire dark matter halos. In this work, we focus on the intermediate regime: forces with range much larger than dark matter particles' inter-particle spacing, but still shorter than the length scales of known halos. We show that gradients in the dark matter density of such halos would still lead to observable effects. We focus primarily on effects in the Bullet Cluster, where finite-range forces would lead either to a modification of the collision velocity of the cluster or to a separation of the dark matter and the galaxies of each cluster after the collision. We also consider constraints from the binding of ultrafaint dwarf galaxy halos, and from gravitational lensing of the Abell 370 cluster. Taken together, these observations allow us to set the strongest constraints on dark matter self-interactions over many orders of magnitude in range below $\sim10$ kpc, surpassing existing limits by orders of magnitude throughout.
title Coherent Self-Interactions of Dark Matter in the Bullet Cluster
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2311.07648