Analytic and numerical study of dark matter halos in the Horndeski theory
Abstract
The models of modified gravity that can explain the late-time accelerated expansion of the Universe must pass the local tests of gravity, introducing a screening mechanism so that any additional fifth force in gravity is suppressed at stellar scales. Dark matter halos, in contrast, by their extendedness in scale, may exhibit a transition of screening to small scales, providing a probe of modified gravity and the origin of the late-time acceleration. We perform comprehensive studies of dark matter halos with Vainshtein screening in the Horndeski theory. Given that dark matter is cold and a dark matter halo is spherically symmetric, we analytically clarify the conditions for the halo profile under which the Vainshtein screening works effectively. We find that the Vainshtein screening is less effective even within the Vainshtein radius as the profile approaches a core-like structure around the center of a halo, which motivates us to postulate that some features owing to the fifth force can survive during the dynamical evolution of a halo. We numerically examine our postulate by a N-body simulation for an isolated halo with the assumption of Newtonian two-body interactions with the spherical external fifth force. We make use of three proxies of the mass through hydrostatic dynamics, the Jeans equation, and gravitational lensing, all of which must be identical in the case of Newtonian gravity as a weak-field approximation to General Relativity. We find that these proxies can be biased relative to each other at a (quasi) equilibrium, quantitatively indicating that the fiducial model of gravity is not Newtonian. Our result affirmatively suggests that multiple mass proxies from observations are capable of testing gravity on halo scales.
Related
- Linear perturbation theory and structure formation in a Horndeski theory of gravity without dark matter
- Testing the Isothermal Jeans Model for Self-interacting Dark Matter Halos in the Collapse Phase
- Core-collapse universality for inelastic self-interacting dark matter halos
- Dynamics of self-gravitating halos with decaying dark matter
- Radial stress in rotating ACKN/KSZ continuations of Einstein-cluster dark matter halos
BibTeX
@misc{onoda2026analytic,
title = {{Analytic and numerical study of dark matter halos in the Horndeski theory}},
author = {Kohei Onoda and Shun Arai and Daisuke Yamauchi and Shuichiro Yokoyama and Shogo Masaki and Kenji Hasegawa},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.22819},
eprint = {2610.22819},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.22819},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Analytic and numerical study of dark matter halos in the Horndeski theory
AU - Kohei Onoda
AU - Shun Arai
AU - Daisuke Yamauchi
AU - Shuichiro Yokoyama
AU - Shogo Masaki
AU - Kenji Hasegawa
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.22819
UR - https://arxiv.org/abs/2610.22819
AB - The models of modified gravity that can explain the late-time accelerated expansion of the Universe must pass the local tests of gravity, introducing a screening mechanism so that any additional fifth force in gravity is suppressed at stellar scales. Dark matter halos, in contrast, by their extendedness in scale, may exhibit a transition of screening to small scales, providing a probe of modified gravity and the origin of the late-time acceleration. We perform comprehensive studies of dark matter halos with Vainshtein screening in the Horndeski theory. Given that dark matter is cold and a dark matter halo is spherically symmetric, we analytically clarify the conditions for the halo profile under which the Vainshtein screening works effectively. We find that the Vainshtein screening is less effective even within the Vainshtein radius as the profile approaches a core-like structure around the center of a halo, which motivates us to postulate that some features owing to the fifth force can survive during the dynamical evolution of a halo. We numerically examine our postulate by a N-body simulation for an isolated halo with the assumption of Newtonian two-body interactions with the spherical external fifth force. We make use of three proxies of the mass through hydrostatic dynamics, the Jeans equation, and gravitational lensing, all of which must be identical in the case of Newtonian gravity as a weak-field approximation to General Relativity. We find that these proxies can be biased relative to each other at a (quasi) equilibrium, quantitatively indicating that the fiducial model of gravity is not Newtonian. Our result affirmatively suggests that multiple mass proxies from observations are capable of testing gravity on halo scales.
ER -