Jeans Model for the Shapes of Self-interacting Dark Matter Halos

Fuente: arXiv
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Auteurs principaux: Bautista, Yilber Fabian, Robertson, Andrew, Sagunski, Laura, Smith-Orlik, Adam, Tulin, Sean
Format: Preprint
Publié: 2025
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author Bautista, Yilber Fabian
Robertson, Andrew
Sagunski, Laura
Smith-Orlik, Adam
Tulin, Sean
author_facet Bautista, Yilber Fabian
Robertson, Andrew
Sagunski, Laura
Smith-Orlik, Adam
Tulin, Sean
contents The Jeans model is a semi-analytical approach to modeling self-interacting dark matter (SIDM) that works remarkably well to reproduce the spherically-averaged halo profiles from observations and simulations of relaxed galaxies and galaxy clusters. However, SIDM halos are not spherically symmetric in general since they respond to nonspherical baryon distributions and retain nonsphericity from their initial collapse. In this work, we generalize the Jeans model to describe SIDM density profiles and halo shapes beyond spherical symmetry. Observational tests via halo shapes are especially important for testing SIDM in massive galaxies, $M_{\rm 200} \sim 10^{12} - 10^{13} \; \Msun$, where SIDM and collisionless dark matter halos can have indistinguishable spherically-averaged profiles but distinct halo shapes. We validate our model by comparing to cosmological simulations with baryons for both SIDM with $\sigmam = 1 \cmg$ and collisionless cold dark matter. Our approach differs from previous work in this direction, taking into account the fact that multiple scatterings are required to impact the shape of the halo, as well as being computationally inexpensive to implement. The nonspherical Jeans model can be used in conjunction with halo shape observations (e.g., from gravitational lensing or X-ray data) to directly constrain dark matter self-interactions.
format Preprint
id arxiv_https___arxiv_org_abs_2511_10765
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Jeans Model for the Shapes of Self-interacting Dark Matter Halos
Bautista, Yilber Fabian
Robertson, Andrew
Sagunski, Laura
Smith-Orlik, Adam
Tulin, Sean
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
The Jeans model is a semi-analytical approach to modeling self-interacting dark matter (SIDM) that works remarkably well to reproduce the spherically-averaged halo profiles from observations and simulations of relaxed galaxies and galaxy clusters. However, SIDM halos are not spherically symmetric in general since they respond to nonspherical baryon distributions and retain nonsphericity from their initial collapse. In this work, we generalize the Jeans model to describe SIDM density profiles and halo shapes beyond spherical symmetry. Observational tests via halo shapes are especially important for testing SIDM in massive galaxies, $M_{\rm 200} \sim 10^{12} - 10^{13} \; \Msun$, where SIDM and collisionless dark matter halos can have indistinguishable spherically-averaged profiles but distinct halo shapes. We validate our model by comparing to cosmological simulations with baryons for both SIDM with $\sigmam = 1 \cmg$ and collisionless cold dark matter. Our approach differs from previous work in this direction, taking into account the fact that multiple scatterings are required to impact the shape of the halo, as well as being computationally inexpensive to implement. The nonspherical Jeans model can be used in conjunction with halo shape observations (e.g., from gravitational lensing or X-ray data) to directly constrain dark matter self-interactions.
title Jeans Model for the Shapes of Self-interacting Dark Matter Halos
topic Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2511.10765