Fully Compressive Tides in Galaxy Mergers

Research output: Contribution to journalArticle


The disruptive effect of galactic tides is a textbook example of gravitational dynamics. However, depending on the shape of the potential, tides can also become fully compressive. When that is the case, they might trigger or strengthen the formation of galactic substructures (star clusters and tidal dwarf galaxies), instead of destroying them. We perform N-body simulations of interacting galaxies to quantify this effect. We demonstrate that tidal compression occurs repeatedly during a galaxy merger, independently of the specific choice of parameterization. With a model tailored to the Antennae galaxies, we show that the distribution of compressive tides matches the locations and timescales of observed substructures. After extending our study to a broad range of parameters, we conclude that neither the importance of the compressive tides (≈15% of the stellar mass) nor their duration (~107 yr) is strongly affected by changes in the progenitors' configurations and orbits. Moreover, we show that individual clumps of matter can enter compressive regions several times in the course of a simulation. We speculate that this may spawn multiple star formation episodes in some star clusters, through, e.g., enhanced gas retention.


External organisations
  • University of Strasbourg
  • University of Vienna
  • Technical University of Munich
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology


  • galaxies: evolution, galaxies: interactions, galaxies: starburst, galaxies: star clusters, stars: formation, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Astrophysics of Galaxies
Original languageEnglish
Pages (from-to)67-82
Number of pages16
Issue number1
Publication statusPublished - 2009 Nov 1
Publication categoryResearch
Externally publishedYes