Issue |
A&A
Volume 690, October 2024
|
|
---|---|---|
Article Number | A214 | |
Number of page(s) | 8 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361/202450985 | |
Published online | 09 October 2024 |
The energy shear of protohaloes
1
Departamento de Física Fundamental and IUFFyM, Universidad de Salamanca,
Plaza de la Merced s/n,
37008
Salamanca,
Spain
2
Dipartimento di Fisica e Astronomia, Alma Mater Studiorum Università di Bologna,
via Gobetti 93/2,
40129
Bologna,
Italy
3
INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna,
Via Piero Gobetti 93/3,
40129
Bologna,
Italy
4
INFN-Sezione di Bologna,
Viale Berti Pichat 6/2,
40127
Bologna,
Italy
5
Center for Particle Cosmology, University of Pennsylvania,
209 S. 33rd St.,
Philadelphia,
PA
19104,
USA
6
The Abdus Salam International Centre for Theoretical Physics,
Strada Costiera 11,
34151
Trieste,
Italy
★ Corresponding author; mmusso@usal.es; shethrk@upenn.edu
Received:
4
June
2024
Accepted:
10
August
2024
As it collapses to form a halo, the shape of a protohalo patch is deformed by the initial shear field. This deformation is often modeled using the ‘deformation’ tensor, constructed from second derivatives of the gravitational potential, whose trace gives the initial overdensity. However, especially for lower mass protohaloes, this matrix is not always positive definite: one of its eigenvalues has a different sign from the others. We argue that the evolution of a patch is better described by the ‘energy shear’ tensor, which is actually positive definite and plays a direct role in the evolution, and test our analytical result against N-body simulations. We discuss the implications of this positive-definiteness for analytical models of halo abundances, assembly and of the cosmic web.
Key words: cosmology: theory / dark matter / large-scale structure of Universe
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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