A new method to measure the mass of galaxy clusters
  The mass measurement of galaxy clusters is an important tool for the
determination of cosmological parameters describing the matter and energy
content of the Universe. However, the standard methods rely on various
assumptions about the shape or the level of equilibrium of the cluster. We
present a novel method of measuring cluster masses. It is complementary to most
of the other methods, since it only uses kinematical information from outside
the virialized cluster. Our method identifies objects, as galaxy sheets or
filaments, in the cluster outer region, and infers the cluster mass by modeling
how the massive cluster perturbs the motion of the structures from the Hubble
flow. At the same time, this technique allows to constrain the
three-dimensional orientation of the detected structures with a good accuracy.
We use a cosmological numerical simulation to test the method. We then apply
the method to the Coma cluster, where we find two galaxy sheets, and measure
the mass of Coma to be Mvir=(9.2\pm2.4)10^{14} Msol, in good agreement with
previous measurements obtained with the standard methods.
