Physicists offer explanation for diverse galaxy rotations

This concept is played out on a cosmological scale by

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galaxies. Two galaxies that appear at first glance to be very similar and effectively identical can have inner regions rotating at very different rates - the galactic analog of twins with different lifestyles.

A team of physicists, led by Hai-Bo Yu of the University of California, Riverside, has found a simple and viable explanation for this diversity.

Every galaxy sits within a dark matter halo that forms the gravitational scaffolding holding it together. The distribution of dark matter in this halo can be inferred from the motion of stars and gas particles in the galaxy.

Yu and colleagues report in Physical Review Letters that diverse galactic-rotation curves, a graph of rotation speeds at different distances from the center, can be naturally explained if dark matter particles are assumed to strongly collide with one another in the inner halo, close to the galaxy's center - a process called dark matter self-interaction.

Read more at: https://phys.org/news/2017-09-physicists-explanation-diverse-galaxy-rotations.html#jCp