Collisionless phase-space transport
Research context
research method · conditional · As of 2026-10-10
A collisionless distribution follows Hamiltonian trajectories in a mean gravitational potential.
Key knowledge
A collisionless distribution follows Hamiltonian trajectories in a mean gravitational potential. Phase-space density is conserved along these trajectories; this approximation does not suppress collective instability or apply when two-body relaxation dominates.
Values and equations
∂f/∂t + v·grad_x f - grad_x Φ·grad_v f = 0
- f
- Declared phase-space density
- v
- Velocity m s^-1
- Φ
- Potential per unit mass m^2 s^-2
- x
- Position m
- t
- Time s
Conditions and scope
- Specify whether f is number- or mass-weighted and integrate consistently.
- Galaxy equilibrium inference additionally requires approximate stationarity and a tracer-selection model.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Collisionless phase-space transport and N-body modeling: Section 12.4.2.2: collisionless equation, characteristics and mean gravitational potential (selected source body inspected).
2026-10-10 · Bounded source check of the recorded statement and conditions. This does not certify a unique physical model, reproduce the cited study or replace independent branch review.
Entry details
Permanent link to this entry ↗- Record identity
- research-earth-collisionless-transport
- Revision
- research.1
- Structured reference record
- Postgraduate & research reference