Substructures in Pal 5’s tidal tails (A. Mastrobuono-Battisti et al.)

Vol. 546
In section 1. Letters

Clumpy streams in a smooth dark halo: the case of Palomar 5

Globular clusters produce long tidal tails, when interacting with the disk and bulge of our Milky Way. The substructures found in the tails have been interpreted as dark matter clumps, since the standard CDM theory predicts a large number ofd small-size objects in the Milky Way halo. For the first time, the authors are able to use numerical simulations to show that the tidal tails around Palomar 5 reveal substructures, even without a clumpy dark matter halo. The substructures are not due to an episodic mass loss, but are related to the local accumulation of orbits of stars that escaped from the globular cluster wand that have very similar positions and velocities.