Statistical mechanics of collisionless orbits. III. comparison with N-body simulations

Liliya L. R. Williams; R. Wojtak; Jens Hjorth

doi:10.1088/0004-637X/725/1/282

Statistical mechanics of collisionless orbits. III. comparison with N-body simulations

Liliya L. R. Williams, R. Wojtak, Jens Hjorth

16 Citationer (Scopus)

Abstract

We compare the DARKexp differential energy distribution, N(ε) αexp(φ₀ - ε) - 1, obtained from statistical mechanical considerations, to the results of N-body simulations of dark matter halos. We first demonstrate that if DARKexp halos had anisotropic velocity distributions similar to those of N-body simulated halos, their density and energy distributions could not be distinguished from those of isotropic DARKexp halos. We next carry out the comparison in two ways, using (1) the actual energy distribution extracted from simulations and (2) N-body fitting formula for the density distribution as well as N(E) computed from the density using the isotropic Eddington formula. Both of the methods independently agree that DARKexp N(E) with φ₀ ≈ 4-5 is an excellent match to N-body N(E). Our results suggest (but do not prove) that statistical mechanical principles of maximum entropy can be used to explain the equilibrated final product of N-body simulations.

Originalsprog	Engelsk
Tidsskrift	Astrophysical Journal
Vol/bind	725
Udgave nummer	1
Sider (fra-til)	282-287
Antal sider	5
ISSN	0004-637X
DOI	https://doi.org/10.1088/0004-637X/725/1/282
Status	Udgivet - 10 dec. 2010

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10.1088/0004-637X/725/1/282

Citationsformater

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title = "Statistical mechanics of collisionless orbits. III. comparison with N-body simulations",

abstract = "We compare the DARKexp differential energy distribution, N(ε) αexp(φ0 - ε) - 1, obtained from statistical mechanical considerations, to the results of N-body simulations of dark matter halos. We first demonstrate that if DARKexp halos had anisotropic velocity distributions similar to those of N-body simulated halos, their density and energy distributions could not be distinguished from those of isotropic DARKexp halos. We next carry out the comparison in two ways, using (1) the actual energy distribution extracted from simulations and (2) N-body fitting formula for the density distribution as well as N(E) computed from the density using the isotropic Eddington formula. Both of the methods independently agree that DARKexp N(E) with φ0 ≈ 4-5 is an excellent match to N-body N(E). Our results suggest (but do not prove) that statistical mechanical principles of maximum entropy can be used to explain the equilibrated final product of N-body simulations.",

author = "Williams, {Liliya L. R.} and R. Wojtak and Jens Hjorth",

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T1 - Statistical mechanics of collisionless orbits. III. comparison with N-body simulations

AU - Williams, Liliya L. R.

AU - Wojtak, R.

AU - Hjorth, Jens

PY - 2010/12/10

Y1 - 2010/12/10

N2 - We compare the DARKexp differential energy distribution, N(ε) αexp(φ0 - ε) - 1, obtained from statistical mechanical considerations, to the results of N-body simulations of dark matter halos. We first demonstrate that if DARKexp halos had anisotropic velocity distributions similar to those of N-body simulated halos, their density and energy distributions could not be distinguished from those of isotropic DARKexp halos. We next carry out the comparison in two ways, using (1) the actual energy distribution extracted from simulations and (2) N-body fitting formula for the density distribution as well as N(E) computed from the density using the isotropic Eddington formula. Both of the methods independently agree that DARKexp N(E) with φ0 ≈ 4-5 is an excellent match to N-body N(E). Our results suggest (but do not prove) that statistical mechanical principles of maximum entropy can be used to explain the equilibrated final product of N-body simulations.

AB - We compare the DARKexp differential energy distribution, N(ε) αexp(φ0 - ε) - 1, obtained from statistical mechanical considerations, to the results of N-body simulations of dark matter halos. We first demonstrate that if DARKexp halos had anisotropic velocity distributions similar to those of N-body simulated halos, their density and energy distributions could not be distinguished from those of isotropic DARKexp halos. We next carry out the comparison in two ways, using (1) the actual energy distribution extracted from simulations and (2) N-body fitting formula for the density distribution as well as N(E) computed from the density using the isotropic Eddington formula. Both of the methods independently agree that DARKexp N(E) with φ0 ≈ 4-5 is an excellent match to N-body N(E). Our results suggest (but do not prove) that statistical mechanical principles of maximum entropy can be used to explain the equilibrated final product of N-body simulations.

U2 - 10.1088/0004-637X/725/1/282

DO - 10.1088/0004-637X/725/1/282

M3 - Journal article

SN - 0004-637X

VL - 725

SP - 282

EP - 287

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

ER -

Statistical mechanics of collisionless orbits. III. comparison with N-body simulations

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