Accretion energy, efficiency and angular-momentum transport
Matter moving inward in a gravitational field can release binding energy if energy is dissipated.
Key knowledge
Matter moving inward in a gravitational field can release binding energy if energy is dissipated. For matter initially nearly at rest far from a Newtonian object of mass M and material radius R, available gravitational power scales as GMṀ/R. A radiated accretion luminosity is often parameterized L_acc=ηṀc² using an explicitly defined inflow rate and radiative efficiency. In a rotating disk, stress transports angular momentum so material can move inward; inflow and radiation need not have a universal efficiency.
Values and equations
L_grav∼GMṀ/R; L_acc=ηṀc²
- L_grav,L_acc
- available Newtonian gravitational power scale and radiated accretion luminosity W
- M
- central object mass kg
- Ṁ
- specified supplied rest-mass flow rate kg s⁻¹
- R
- material radius in the weak-field estimate m
- η
- defined radiative efficiency 1
- G
- gravitational constant m³ kg⁻¹ s⁻²
- c
- vacuum light speed m s⁻¹
Conditions and scope
- The Newtonian estimate assumes GM/(Rc²) much smaller than one and specifies initial/final energy and boundary conditions. A circular-orbit disk, a material boundary layer and a black-hole inner boundary have different budgets.
- η is radiative output divided by supplied rest-mass-energy rate, not automatically the black-hole growth rate. Outflows, heat advection, magnetic stresses and relativistic spacetime alter the relation; no fixed η or full GR/MHD solution is supplied.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Cole Miller — University of Maryland ASTR3502 sources
- Lecture15, PDF pages12–13 and17–20: specific gravitational energy, luminosity and outward angular-momentum transferCole Miller — University of Maryland ASTR350Reference guide · PDF
- Lecture20 key points, item5: definition of radiative efficiencyCole Miller — University of Maryland ASTR350Reference guide · PDF
Evidence and review
Read the actual accretion/rotating-disk/stress body and explicit efficiency definition. GM/R is the available Newtonian gravitational energy per unit supplied mass; multiplying by the specified mass inflow rate gives the gravitational power scale GMṀ/R. These are not an exact thin-disk luminosity or a universal relativistic radiative efficiency. Excluded source every-stellar-BH-single-birth channel, universal growth-time conclusion and treating angular momentum as destroyed rather than transported.
2026-10-10 · Independent AI editorial review: All44 exact root-authored compact records, equations/variable units/conditions and140 origin edges accepted after independently reading final6/18 with bounded primary bodies and matching prior38/122 scientific fingerprints unchanged. Exact claim/edge review is distinct from combined inventory scope and separate CLE26 approval; no entire cited books or old-corpus experimental revalidation is asserted. Receipt: cosmos-completion-independent-content-and-inventory-review.1.
Entry details
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- uni-cosmos-accretion-energy-budget
- Revision
- core.1.accretion-energy-precision-20261012.1
- Structured reference record
- University core expansion