The March 2015 Superstorm Revisited: Phase Space Density Profiles and Fast ULF Wave Diffusive Transport

2019 ◽  
Vol 124 (2) ◽  
pp. 1143-1156 ◽  
Author(s):  
L. G. Ozeke ◽  
I. R. Mann ◽  
S. G. Claudepierre ◽  
M. Henderson ◽  
S. K. Morley ◽  
...  
Keyword(s):  
Phase Space ◽  
Phase Space Density ◽  
Diffusive Transport ◽  
Density Profiles ◽  
Space Density ◽  
Ulf Wave

scholarly journals On the apparent power law in CDM halo pseudo-phase space density profiles

2017 ◽  
Vol 470 (1) ◽  
pp. 500-511 ◽  
Author(s):  
Ethan O. Nadler ◽  
S. Peng Oh ◽  
Suoqing Ji
Keyword(s):  
Phase Space ◽  
Power Law ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Phase Space Density ◽  
Fluid Approximation ◽  
Density Profiles ◽  
Space Density ◽  
Scale Free ◽  
Hydrodynamic Calculations

Abstract We investigate the apparent power-law scaling of the pseudo-phase space density (PPSD) in cold dark matter (CDM) haloes. We study fluid collapse, using the close analogy between the gas entropy and the PPSD in the fluid approximation. Our hydrodynamic calculations allow for a precise evaluation of logarithmic derivatives. For scale-free initial conditions, entropy is a power law in Lagrangian (mass) coordinates, but not in Eulerian (radial) coordinates. The deviation from a radial power law arises from incomplete hydrostatic equilibrium (HSE), linked to bulk inflow and mass accretion, and the convergence to the asymptotic central power-law slope is very slow. For more realistic collapse, entropy is not a power law with either radius or mass due to deviations from HSE and scale-dependent initial conditions. Instead, it is a slowly rolling power law that appears approximately linear on a log–log plot. Our fluid calculations recover PPSD power-law slopes and residual amplitudes similar to N-body simulations, indicating that deviations from a power law are not numerical artefacts. In addition, we find that realistic collapse is not self-similar; scalelengths such as the shock radius and the turnaround radius are not power-law functions of time. We therefore argue that the apparent power-law PPSD cannot be used to make detailed dynamical inferences or extrapolate halo profiles inwards, and that it does not indicate any hidden integrals of motion. We also suggest that the apparent agreement between the PPSD and the asymptotic Bertschinger slope is purely coincidental.

Magnetopause Shadowing Characteristics in Phase Space Density Measurements

2021 ◽  
Author(s):  
Frances Staples ◽  
Jonathan Rae ◽  
Adam Kellerman ◽  
Kyle Murphy ◽  
Jasmine Sandhu ◽  
...  
Keyword(s):  
Phase Space ◽  
Radiation Belt ◽  
Interplanetary Space ◽  
Phase Space Density ◽  
Electron Dynamics ◽  
Rapid Loss ◽  
Space Density ◽  
Ulf Wave ◽  
The Earth ◽  
Flux Increase

<p>Loss mechanisms act independently or in unison to drive rapid loss of electrons in the radiation belts. Electrons may be lost by precipitation into the Earth’s atmosphere, or through the magnetopause into interplanetary space. Whilst this magnetopause shadowing is well understood to produce dropouts in electron flux, it is less clear if shadowing continues to remove particles in tandem with electron acceleration processes, limiting the overall flux increase. </p><p>We investigate the contribution of shadowing to overall radiation belt fluxes throughout a geomagnetic storm in early September 2017. We use new, multi-spacecraft phase space density calculations to decipher electron dynamics during each storm phase and identify features of magnetopause shadowing during both the net-loss and the net-acceleration storm phases. We also highlight two distinct types of shadowing; ‘Indirect’, where electrons are lost through ULF wave driven radial transport towards the magnetopause boundary, and ‘direct’, where electrons are lost as their orbit intersects the magnetopause. </p>

scholarly journals The density and pseudo-phase-space density profiles of cold dark matter haloes

2011 ◽  
Vol 415 (4) ◽  
pp. 3895-3902 ◽  
Author(s):  
Aaron D. Ludlow ◽  
Julio F. Navarro ◽  
Simon D. M. White ◽  
Michael Boylan-Kolchin ◽  
Volker Springel ◽  
...  
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Cold Dark Matter ◽  
Phase Space Density ◽  
Density Profiles ◽  
Space Density

scholarly journals DISTRIBUTION FUNCTION IN THE CENTER OF THE DARK MATTER HALO

2009 ◽  
Vol 18 (03) ◽  
pp. 477-484
Author(s):  
DING MA ◽  
PING HE
Keyword(s):  
Dark Matter ◽  
Distribution Function ◽  
Phase Space ◽  
Velocity Dispersion ◽  
Anisotropy Parameter ◽  
Dark Matter Halo ◽  
Phase Space Density ◽  
Dark Matter Halos ◽  
Density Profiles ◽  
Space Density

N-body simulations of dark matter halos show that the density profiles of the halos behave as ρ(r) ∝ r-α(r), where the density logarithmic slope α ≃ 1–1.5 in the center and α ≃ 3–4 in the outer parts of the halos. However, some observations are not in agreement with simulations in the very central region of the halos. The simulations also show that the velocity dispersion anisotropy parameter β ≈ 0 in the inner part of the halo and the so-called pseudo–phase-space density ρ/σ3 behaves as a power law in radius r. With these results in mind, we study the distribution function and the pseudo–phase-space density ρ/σ3 of the center of dark matter halos and find that they are closely related.

scholarly journals Phase-space density profiles in scale-free cosmologies

2008 ◽  
Vol 391 (2) ◽  
pp. 559-564 ◽  
Author(s):  
Steffen R. Knollmann ◽  
Alexander Knebe ◽  
Yehuda Hoffman
Keyword(s):  
Phase Space ◽  
Phase Space Density ◽  
Density Profiles ◽  
Space Density ◽  
Scale Free

On the Pseudo Phase-space Density of Dark Matter Haloes and the Universality of Density Profiles

2015 ◽  
Vol 24 (3) ◽  
Author(s):  
A. Del Popolo
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Radial Dependence ◽  
Phase Space Density ◽  
Density Profiles ◽  
Space Density

AbstractWe examine the radial dependence of the pseudo phase-space density,

scholarly journals CLASH-VLT: The mass, velocity-anisotropy, and pseudo-phase-space density profiles of thez= 0.44 galaxy cluster MACS J1206.2-0847

2013 ◽  
Vol 558 ◽  
pp. A1 ◽  
Author(s):  
A. Biviano ◽  
P. Rosati ◽  
I. Balestra ◽  
A. Mercurio ◽  
M. Girardi ◽  
...  
Keyword(s):  
Phase Space ◽  
Mass Velocity ◽  
Galaxy Cluster ◽  
Phase Space Density ◽  
Density Profiles ◽  
Space Density ◽  
Velocity Anisotropy
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