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Résumé |
Galaxy clusters are immensely fruitful
laboratories for cosmology. In
the past three decades, great progress has
been made in understanding
their composition, dynamics, and role in
the cosmic web. Cluster
interiors, i.e., their relaxed parts, are
well understood by now, as
they have been exhaustively studied.
However, we have not taken full
advantage of their outer portions, which
are arguably equally rich in
terms of their potential to help us
understand the cosmos.
In the past two years, we have developed
the understanding that a very
important scale for cosmology is the
turnaround scale, which is the
scale around a cluster after which
galaxies join the Hubble flow. We
have now developed analytical descriptions
of the outer portion of
cluster density profiles on the turnaround
scale as well as mass
scaling relations connecting overdensity
masses (such as M200) at the
interior of clusters with the turnaround
mass. Being equipped with a
density profile sensitive to the
turnaround scale and a scaling
relation for determining the mass enclosed
therein we can build a
novel test for our cosmology. |
