A Derivation of (Half) the Dark Matter Distribution Function

Steen Harle Hansen; Martin Sparre

doi:10.1088/0004-637X/756/1/100

A Derivation of (Half) the Dark Matter Distribution Function

Steen Harle Hansen, Martin Sparre

DARK

3 Citationer (Scopus)

Abstract

All dark matter structures appear to follow a set of universalities, such as phase-space density or velocity anisotropy profiles; however, the origin of these universalities remains a mystery. Any equilibrated dark matter structure can be fully described by two functions, namely the radial and tangential velocity distribution functions (VDFs), and once these two are understood we will understand all the observed universalities. Here, we demonstrate that if we know the radial VDF then we can derive and understand the tangential VDF. This is based on simple dynamical arguments about properties of collisionless systems. We use a range of controlled numerical simulations to demonstrate the accuracy of this result. We therefore boil the question of the dark matter structural properties down to understanding the radial VDF.

Originalsprog	Engelsk
Tidsskrift	Astrophysical Journal
Vol/bind	756
Udgave nummer	1
Sider (fra-til)	100
ISSN	0004-637X
DOI	https://doi.org/10.1088/0004-637X/756/1/100
Status	Udgivet - 1 sep. 2012

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10.1088/0004-637X/756/1/100

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AU - Sparre, Martin

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N2 - All dark matter structures appear to follow a set of universalities, such as phase-space density or velocity anisotropy profiles; however, the origin of these universalities remains a mystery. Any equilibrated dark matter structure can be fully described by two functions, namely the radial and tangential velocity distribution functions (VDFs), and once these two are understood we will understand all the observed universalities. Here, we demonstrate that if we know the radial VDF then we can derive and understand the tangential VDF. This is based on simple dynamical arguments about properties of collisionless systems. We use a range of controlled numerical simulations to demonstrate the accuracy of this result. We therefore boil the question of the dark matter structural properties down to understanding the radial VDF.

AB - All dark matter structures appear to follow a set of universalities, such as phase-space density or velocity anisotropy profiles; however, the origin of these universalities remains a mystery. Any equilibrated dark matter structure can be fully described by two functions, namely the radial and tangential velocity distribution functions (VDFs), and once these two are understood we will understand all the observed universalities. Here, we demonstrate that if we know the radial VDF then we can derive and understand the tangential VDF. This is based on simple dynamical arguments about properties of collisionless systems. We use a range of controlled numerical simulations to demonstrate the accuracy of this result. We therefore boil the question of the dark matter structural properties down to understanding the radial VDF.

U2 - 10.1088/0004-637X/756/1/100

DO - 10.1088/0004-637X/756/1/100

M3 - Journal article

SN - 0004-637X

VL - 756

SP - 100

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

ER -

A Derivation of (Half) the Dark Matter Distribution Function

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