In an article on SpaceFlight Now, researchers at the University of California, Santa Cruz (which operates the Lick Obeservatory just outside San Jose, CA) have used NASA’s most powerful supercomputer to run the largest simulation to date of the formation and evolution of the dark matter halo that envelopes the Milky Way galaxy. Their results show substructures within the halo in unprecedented detail, providing a valuable tool for understanding the evolutionary history of our galaxy.
Every galaxy is surrounded by a halo of mysterious dark matter that can only be detected indirectly by observing its gravitational effects. The invisible halo is much larger and more spherical than the luminous galaxy at its center. Recent computer simulations have shown that the halo is surprisingly clumpy, with relatively dense concentrations of dark matter in gravitationally bound ‘subhalos’ within the halo. The new study, which has been accepted for publication in the Astrophysical Journal, shows much more extensive substructure than any previous study.
Dark Matter comprises an estimated 4/5ths of the total mass of the universe. In a previous post (Dark Matter Observed) I linked to a page showing an animation of a model of a collision between two galactic clusters, showing how the dark matter ‘sailed ahead’ of the luminous matter.