Tracing the dark matter sheet in phase space

By Tom Abel, Oliver Hahn, Ralf Kaehler. 2011

151 citations recorded by the source corpus.

The primordial velocity dispersion of dark matter is small compared to the velocities attained during structure formation. The initial density distribution is close to uniform and it occupies an initial sheet in phase-space that is single valued in velocity space. Because of gravitational forces, this three dimensional manifold evolves in phase-space without ever tearing, conserving phase-space volume and preserving the connectivity of nearby points. N{body simulations already follow the motion of this sheet in phase-space. This fact can be used to extract full ne-grained phase-space structure information from existing cosmological N{body simulations. Particles are considered as the vertices of an unstructured three dimensional mesh moving in six dimensional phase-space. On this mesh, mass density and momentum are uniquely dened. We show how to obtain the space density of the uid, detect caustics, and count the number of streams as well as their individual contributions to any point in conguration-spac e. We calculate the bulk velocity, local velocity dispersions, and densities from the sheet { all without averaging over control volumes. This gives a wealth of new information about dark matter uid ow which had previously been thought of as inaccessible to N{body simulations. We outline how this mapping may be used to create new accurate collisionless uid simulation codes that may be able to overcome the sparse sampling and unphysical two-body eects that

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/6eb8980e83e723fca761a7e5787e8f9dbae8c43c

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Citations in the corpus

The warm dark matter halo mass function below the cut-off scale (2013, methodology): “Some of the measures introduced in Abel et al. (2012) or methods inspecting the shape of the Lagrangian patch of the identified structures (such as that proposed by e.g. Lovell et al. 2012) may help in automating such a procedure.”
Galactic Searches for Dark Matter (2012, background): “These features are not seen in the individual velocity components, which are well-described by gaussians of different widths; the triaxiality of the VDF is clearly indicated in Vogelsberger et al. (2009) and Abel et al. (2011).”
FIRE-2 simulations: physics versus numerics in galaxy formation (2017, background): “Particle-based codes in galaxy formation have proved a surprising historical exception. c© 0000 RAS, MNRAS 000, 000–000 ticle distribution and their phase-space distribution; for discussion see Abel et al. 2012).”
NEXUS: Tracing the cosmic web connection (2012, methodology): “In a sequence of studies that follows up on this idea (Abel et al. 2011; Shandarin et al. 2012; Neyrinck 2012), the full phase space structure of the mass distribution is used for an impressively accurate dynamical characterization of morphological structure of the Cosmic Web.”
Evolution of the cosmic web (2014, methodology): “In particular, the analysis of the DM phase-space sheet illustrated in Shandarin et al. (2012, see also Abel et al. 2012; Falck et al. 2012) gives a very natural way of characterizing large-scale structures.”
Tracing the cosmic web (2017, methodology): “…dynamical evolution of the cosmic web has been the uncovering of the intimate link between the emerging anisotropic structures and the multistream migration flows involved in the buildup of cosmic structure (Shandarin 2011; Shandarin et al. 2012; Falck et al. 2012; Neyrinck 2012; Abel et al. 2012).”