What does the Bullet Cluster tell us about Self-Interacting Dark Matter?

By Andrew Robertson, Richard J. Massey, V. Eke. 2016

199 citations recorded by the source corpus.

We perform numerical simulations of the merging galaxy cluster 1E 0657−56 (the Bullet Cluster), including the effects of elastic dark matter scattering. In a similar manner to the stripping of gas by ram pressure, dark matter self-interactions would transfer momentum between the two galaxy-cluster dark matter haloes, causing them to lag behind the collisionless galaxies. The absence of an observed separation between the dark matter and stellar components in the Bullet Cluster has been used to place upper limits on the cross-section for dark matter scattering. We emphasize the importance of analysing simulations in an observationally motivated manner, finding that the way in which the positions of the various components are measured can have a larger impact on derived constraints on dark matter's self-interaction cross-section than reasonable changes to the initial conditions for the merger. In particular, we find that the methods used in previous studies to place some of the tightest constraints on this cross-section do not reflect what is done observationally, and overstate the Bullet Cluster's ability to constrain the particle properties of dark matter. We introduce the first simulations of the Bullet Cluster including both self-interacting dark matter and gas. We find that as the gas is stripped it introduces radially dependent asymmetries into the stellar and dark matter distributions. As the techniques used to determine the positions of the dark matter and galaxies are sensitive to different radial scales, these asymmetries can lead to erroneously measured offsets between dark matter and galaxies even when they are spatially coincident.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/730acc3b271fdeee1c5f8e374d5e0c625f5d1894

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Citations in the corpus

Massive Primordial Black Holes as Dark Matter and their detection with Gravitational Waves (2017, methodology): “The bullet cluster is used to constrain models of PDM by setting stringent limits on the interaction cross-sections of DM particles, σ/M < 1 cm2/g [76], which can be evaded by PBH with Schwarzschild-Born cross-sections and M ∼ 50 M , by many orders of magnitude.”
Gravitational probes of dark matter physics (2017, background): “However, recent works shows that the separation between dark matter and galaxies is expected to be small in SIDM during the merger, in some cases much smaller than the observed separations, even for large (σ/m ∼ 10 cm(2)/g) cross sections [227, 228, 232, 230, 231].”