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Rotational and turbulent motion can deepen a gravity well in a galaxy or galaxy cluster. In an analysis of the mass components of a large body, this would appear to be one of the components. Does it have a name to distinguish it from the other components (e.g. Stellar Mass, Gas Mass, Dark Mass)?

I've seen the term Dynamical Mass, but that appears to be primarily related to the mass derived from a Virial Analysis.

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    $\begingroup$ How can rotational and turbulent motion can deepen a gravity well? Kinetic energy does contribute to the stress-energy tensor, but this isn't likely to be significant outside extreme situations like black holes. $\endgroup$
    – John Rennie
    Commented Nov 4, 2015 at 12:51
  • $\begingroup$ I'm sure I'm not phrasing this well, so pardon my clumsiness. $m\frac{v^2}{r} = \sum_i F_{I}$. If you assume there is no rotation in a galaxy cluster, the left size will be zero and you're left with a pure hydrostatic equilibrium equation. If you discover rotation and turbulence in the same galaxy cluster, then the mass on the left side of the equation will be non-zero. Does that difference have a name? Would it be something like a 'non-Thermal Pressure Gradient Force'? $\endgroup$
    – user32023
    Commented Nov 4, 2015 at 14:23

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Rotational and turbulent motion cannot "deepen" the gravity well in a galaxy of galaxy cluster. The contribution of kinetic energy to the stress-energy tensor is negligible compared to the rest-mass energy in non-relativistic systems.

Assuming you mean something like, 'how does rotational and turbulent motion contribute to the equilibrium configuration of a dynamical system?' --- then the answer is that they do contribute support against collapse. People are usually pretty sloppy in the terminology, but I think, the rotational motion would go towards "rotational support" (via centrifugal terms) and the turbulent motion would generally be grouped into "thermal support"*.

*For gas-motion scale turbulence this is a good, appropriate terminology. But for stellar motion (radial and epicyclic motion, etc) it is more based on analogy to thermal terms in the equilibrium equations.

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  • $\begingroup$ Modified the question to reflect your suggestion. BTW, just got through reading a piece by Molnar et al (2013) where they used the phrase "non-thermal pressure support" to describe everything that wasn't provided by the Ideal Gas Law. Apparently there's a significant amount even in relaxed clusters. $\endgroup$
    – user32023
    Commented Nov 4, 2015 at 22:27

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