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Main Authors: Giffin, Pierce, Liu, Andrew, Boucsein, Jeremias, Cruz, Akaxia, Prabhu, Anirudh, Profumo, Stefano, Roberts, M. Grant
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2511.15810
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author Giffin, Pierce
Liu, Andrew
Boucsein, Jeremias
Cruz, Akaxia
Prabhu, Anirudh
Profumo, Stefano
Roberts, M. Grant
author_facet Giffin, Pierce
Liu, Andrew
Boucsein, Jeremias
Cruz, Akaxia
Prabhu, Anirudh
Profumo, Stefano
Roberts, M. Grant
contents Long-range interactions in the dark sector can give rise to collective plasma phenomena that are capable of modifying the evolution of dark matter halos. We present the first study of gravitational collapse in a secluded dark $U(1)_D$ model using a magnetohydrodynamic description of the dark matter. We show that dark magnetic fields generate an anisotropic pressure that alters the Jeans scale and suppresses small-scale power in a direction-dependent manner. For a range of primordial magnetic spectral indices, this effect produces distinctive modifications to the linear matter power spectrum. We find that current observations cannot yet constrain viable dark magnetic fields, as CMB tensor modes mostly provide more stringent constraints. Nevertheless, forthcoming high-resolution probes of the matter power spectrum (CMB-HD lensing, HERA, and EDGES) will be able to test these predictions and are sensitive to dark charge-to-mass ratios in the range $10^{-20}\,\text{GeV}^{-1}\lesssim q_χ/m_χ\lesssim 10^{-14}\,\text{GeV}^{-1}$.
format Preprint
id arxiv_https___arxiv_org_abs_2511_15810
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Structure Formation with Dark Magnetohydrodynamics
Giffin, Pierce
Liu, Andrew
Boucsein, Jeremias
Cruz, Akaxia
Prabhu, Anirudh
Profumo, Stefano
Roberts, M. Grant
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
Long-range interactions in the dark sector can give rise to collective plasma phenomena that are capable of modifying the evolution of dark matter halos. We present the first study of gravitational collapse in a secluded dark $U(1)_D$ model using a magnetohydrodynamic description of the dark matter. We show that dark magnetic fields generate an anisotropic pressure that alters the Jeans scale and suppresses small-scale power in a direction-dependent manner. For a range of primordial magnetic spectral indices, this effect produces distinctive modifications to the linear matter power spectrum. We find that current observations cannot yet constrain viable dark magnetic fields, as CMB tensor modes mostly provide more stringent constraints. Nevertheless, forthcoming high-resolution probes of the matter power spectrum (CMB-HD lensing, HERA, and EDGES) will be able to test these predictions and are sensitive to dark charge-to-mass ratios in the range $10^{-20}\,\text{GeV}^{-1}\lesssim q_χ/m_χ\lesssim 10^{-14}\,\text{GeV}^{-1}$.
title Structure Formation with Dark Magnetohydrodynamics
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2511.15810