Proof of dark matter existence and other results from a collision of galaxy clusters
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Maxim Markevitch(Harvard-Smithsonian CfA Cambridge, USA/Space Research Inst., Moscow, Russia)
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US/Central
Salle 101 (LAL)
Salle 101
LAL
Bât. 200 - Orsay
Description
Collisions of galaxy clusters are unique experiments that nature stages for us
to study the properties of normal and dark matter that are inaccessible by other
means. I will review recent results obtained using the merging cluster 1E0657-56.
A combination of a long Chandra X-ray observation with accurate weak and strong
gravitational lensing maps has provided the first direct, model-independent proof of
the dark matter existence (as opposed to the modified gravity paradigm), and a direct
constraint on self-interaction cross-section of the dark matter particles. This cluster
also exhibits a rare example of a shock front in the intergalactic gas. Its X-ray
observations can be used for interesting physical tests, such as determining the
electron-ion equilibration timescale in magnetized astrophysical plasmas.