Development of multiple tidal tails around globular clusters and dwarf satellite galaxies

TL;DR

This study uses N-body simulations to show that globular clusters and dwarf galaxies develop multiple tidal tails through repeated orbital passages, with tail features serving as indicators of orbital history.

Contribution

It reveals that multiple tidal tails form around satellites due to repeated apocentre passages, providing a new way to trace orbital periods from observed tidal features.

Findings

Multiple tidal tails form at each apogalacticon passage.

Tidal tail pairs have similar energy and angular momentum distributions.

Density profiles of tidal tails are consistent across formation episodes.

Abstract

The formation and evolution of tidal tails like those observed around some globular clusters and dwarf satellite galaxies is examined with an N-body simulation. In particular, we analyse in detail the evolving tidal features of a one-component satellite that is moving on a highly eccentric orbit in the external field of a host galaxy potential like our own. The results show that every time the satellite approaches apogalacticon, a fresh pair of tidal tails becomes notably prominent, and that eventually, the satellite possesses multiple tidal tails via repeating apocentre passages. Accordingly, the number of observed tidal arms can be used as a tracer of the number of orbital periods that such a system has completed around the centre of its host galaxy. By identifying the arm particles included in each of the first three consecutively formed pairs of tidal tails, we find that each pair of tidal tails is practically identical to one another regarding the energy and angular-momentum distributions. In addition, we demonstrate that the density profiles of these three pairs of tidal tails at their first apogalacticons after formation agree well with one another. It therefore follows that the multiplicity in tidal features originates from the repeated episode of tidal-arm formation in the course of the precessing motion of a satellite.