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

Abstract

By means of direct N-body simulations and simplified numerical models, we study the formation and characteristics of the tidal tails around Palomar 5, along its orbit in the Milky Way potential. Unlike previous findings, we are able to reproduce the substructures observed in the stellar streams of this cluster, without including any lumpiness in the dark matter halo. We show that overdensities similar to those observed in Palomar 5 can be reproduced by the epicyclic motion of stars along its tails, i.e. a simple local accumulation of orbits of stars that escaped from the cluster with very similar positions and velocities. This process is able to form stellar clumps at distances of several kiloparsecs from the cluster, so it is not a phenomenon confined to the inner part of Palomar 5's tails, as previously suggested. Our models can reproduce the density contrast between the clumps and the surrounding tails found in the observed streams, without including any lumpiness in the dark halo, suggesting new upper limits on its granularity.

6 pages, 7 figures. A&A Letters, accepted. Top panel of Fig. A1 replaced, minor typos corrected. High resolution version available at http://mygepi.obspm.fr/~paola/Pal5/

References in corpus (5)

• A 22 Degree Tidal Tail for Palomar 5
• On the structure of tidal tails
• The orbits of 48 globular clusters in a Milky-Way-Like Barred Galaxy
• Formation and evolution of clumpy tidal tails around globular clusters
• The Tidal Tails of 47 Tucanae

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• New Determination of Fundamental Properties of Palomar 5 Using Deep DESI Imaging Data
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