The properties of cosmic velocity fields
- Autor(en)
- Oliver Hahn, Raul E. Angulo, Tom Abel
- Abstrakt
Understanding the velocity field is very important for modern cosmology: it gives insights to structure formation in general, and also its properties are crucial ingredients in modelling redshift-space distortions and in interpreting measurements of the kinetic Sunyaev-Zeldovich effect. Unfortunately, characterizing the velocity field in cosmological N-body simulations is inherently complicated by two facts. (i) The velocity field becomes manifestly multivalued after shell crossing and has discontinuities at caustics. This is due to the collisionless nature of dark matter. (ii) N-body simulations sample the velocity field only at a set of discrete locations, with poor resolution in low-density regions. In this paper, we discuss how the associated problems can be circumvented by using a phase-space interpolation technique. This method provides extremely accurate estimates of the cosmic velocity fields and its derivatives, which can be properly defined without the need of the arbitrary `coarse-graining' procedure commonly used. We explore in detail the configuration-space properties of the cosmic velocity field on very large scales and in the highly non-linear regime. In particular, we characterize the divergence and curl of the velocity field, present their one-point statistics, analyse the Fourier-space properties, and provide fitting formulae for the velocity divergence bias relative to the non-linear matter power spectrum. We furthermore contrast some of the interesting differences in the velocity fields of warm and cold dark matter models. We anticipate that the high-precision measurements carried out here will help to understand in detail the dynamics of dark matter and the structures it forms.
- Organisation(en)
- Institut für Astrophysik, Institut für Mathematik
- Externe Organisation(en)
- Department of Physics, ETH Zurich, CH-8093 Zürich, Switzerland oliver.hahn@oca.eu, Centro de Estudios de Fisica del Cosmos de Aragón, San Juan, 1 Planta-2, E-44001 Teruel, Spain, Stanford University
- Journal
- Monthly Notices of the Royal Astronomical Society
- Band
- 454
- Seiten
- 3920-3937
- Anzahl der Seiten
- 18
- ISSN
- 0035-8711
- DOI
- https://doi.org/10.1093/mnras/stv2179
- Publikationsdatum
- 12-2015
- Peer-reviewed
- Ja
- ÖFOS 2012
- 103044 Kosmologie
- Schlagwörter
- ASJC Scopus Sachgebiete
- Astronomy and Astrophysics, Space and Planetary Science
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/0172dbd4-bfc6-446a-94a0-28e527f9c3ad