هموگش ِ لیزر-آیروین hamugeš-e Layzer-Irvine
*Fr.: équation de Layzer-Irvine*
The ordinary Newtonian energy conservation equation when expressed in expanding
cosmological coordinates. More specifically, it is
the relation between the → *kinetic energy*
per unit mass associated with the motion of
matter relative to the general → *expansion of the Universe*
and the → *gravitational potential energy*
per unit mass associated with the departure from
a homogeneous mass distribution. In other words, it deals with how the energy of the
→ *Universe* is
partitioned between kinetic and potential energy.
Also known as → *cosmic energy equation*.
In its original form, the Layzer-Irvine equation accounts for the
evolution of the energy of a system of → *non-relativistic*
particles, interacting only through gravity, until → *virial equilibrium*
is reached. But it has recently been generalized
to account for interaction between → *dark matter*
and a homogeneous → *dark energy* component. Thus,
it describes the dynamics of local
dark matter perturbations in an otherwise homogeneous
and → *isotropic Universe*
(P. P. Avelino and C. F. V. Gomes, 2013, arXiv:1305.6064). W. M. Irvine, 1961, Ph.D. thesis, Harvard University;
D. Layzer, 1963, Astrophys. J. 138, 174; → *equation*. |