Simulations of galaxy cluster mergers with velocity-dependent, rare and frequent self-interactions
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| Format: | Preprint |
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2023
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| _version_ | 1866913412570677248 |
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| author | Sabarish, V. M. Brüggen, Marcus Schmidt-Hoberg, Kai Fischer, Moritz S. Kahlhoefer, Felix |
| author_facet | Sabarish, V. M. Brüggen, Marcus Schmidt-Hoberg, Kai Fischer, Moritz S. Kahlhoefer, Felix |
| contents | Self-interacting dark matter (SIDM) has been proposed to solve small-scale problems in $Λ$CDM cosmology. In previous work, constraints on the self-interaction cross-section of dark matter have been derived assuming that the self-interaction cross-section is independent of velocity. However, a velocity-dependent cross-section is more natural in most theories of SIDM. Using idealized $N$-body simulations without baryons, we study merging clusters with velocity-dependent SIDM. In addition to the usual rare scattering in the isotropic limit, we also simulate these systems with anisotropic, small-angle (frequent) scatterings. We find that the collision-less brightest cluster galaxy (BCG) has an offset from the DM peak that grows at later stages. Finally, we also extend the existing upper bounds on the velocity-independent, isotropic self-interaction cross-section to the parameter space of rare and frequent velocity-dependent self-interactions by studying the central densities of dark matter-only isolated haloes. For these upper-bound parameters, the DM-BCG offsets just after the first pericentre in the dark matter-only simulations are found to be $\leq$ 10 kpc. On the other hand, because of BCG oscillations, we speculate that the distribution of BCG offsets in a relaxed cluster is a statistically viable probe. Therefore, this motivates further studies of BCG off-centring in hydrodynamic cosmological simulations. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2310_07769 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Simulations of galaxy cluster mergers with velocity-dependent, rare and frequent self-interactions Sabarish, V. M. Brüggen, Marcus Schmidt-Hoberg, Kai Fischer, Moritz S. Kahlhoefer, Felix Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies High Energy Physics - Phenomenology Self-interacting dark matter (SIDM) has been proposed to solve small-scale problems in $Λ$CDM cosmology. In previous work, constraints on the self-interaction cross-section of dark matter have been derived assuming that the self-interaction cross-section is independent of velocity. However, a velocity-dependent cross-section is more natural in most theories of SIDM. Using idealized $N$-body simulations without baryons, we study merging clusters with velocity-dependent SIDM. In addition to the usual rare scattering in the isotropic limit, we also simulate these systems with anisotropic, small-angle (frequent) scatterings. We find that the collision-less brightest cluster galaxy (BCG) has an offset from the DM peak that grows at later stages. Finally, we also extend the existing upper bounds on the velocity-independent, isotropic self-interaction cross-section to the parameter space of rare and frequent velocity-dependent self-interactions by studying the central densities of dark matter-only isolated haloes. For these upper-bound parameters, the DM-BCG offsets just after the first pericentre in the dark matter-only simulations are found to be $\leq$ 10 kpc. On the other hand, because of BCG oscillations, we speculate that the distribution of BCG offsets in a relaxed cluster is a statistically viable probe. Therefore, this motivates further studies of BCG off-centring in hydrodynamic cosmological simulations. |
| title | Simulations of galaxy cluster mergers with velocity-dependent, rare and frequent self-interactions |
| topic | Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2310.07769 |