Getting in shape with minimal energy. A variational principle for protohaloes

Abstract

In analytical models of structure formation, protohalos are routinely assumed to be peaks of the smoothed initial density field, with the smoothing filter being spherically symmetric. This works reasonably well for identifying a protohalo's center of mass, but not its shape. To provide a more realistic description of protohalo boundaries, one must go beyond the spherical picture. We suggest that this can be done by looking for regions of fixed volume, but arbitrary shape, that minimize the enclosed energy. Such regions are surrounded by surfaces over which (a slightly modified version of) the gravitational potential is constant. We show that these equipotential surfaces provide an excellent description of protohalo shapes, orientations and associated torques.

arXiv comment5 pages, 6 figures

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Cited by in corpus (5)

• Accurate halo mass functions from the simplest excursion set theory
• The energy shear of protohaloes
• The AIDA-TNG project: 3D halo shapes
• A universal and physically motivated threshold for Hessian-based cosmic web identification: V-Web case
• The role of energy shear in the collapse of protohaloes