For cluster of galaxies we can observe velocity distributions and so we can deduce mass from multiwavelength observations. I suppose total mass of the cluster could be deduced by observing velocities of galaxies and applying virial theorem. Is it be done using general relativity or just with classical mechanics ?

An other way could be whith looking at gravitational lensing it causes on far galaxies.

Are these two methods giving same results ?

  • $\begingroup$ Classical mechanics is all that is needed. And yes. I'll let someone else provide the details. $\endgroup$
    – ProfRob
    Nov 14, 2018 at 14:18


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