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Energy evolution in the progenitor of galaxy shells: a semi-analytical model

Beibei Guo, Xufen Wu, Hongsheng Zhao, Lulu Fan

Research output: Contribution to journalArticlepeer-review

Abstract

The stellar shells surrounding an elliptical galaxy, as remnants of a dwarf galaxy disrupted during merging, reveal the distribution of energy and angular momentum of the progenitor dwarf galaxy. We develop a semi-analytical model to describe the changes in energy ΔEi and angular momentum ΔLzi for particles during the first infall. We show that these changes, induced by the self-gravity of the progenitor, are important in broadening the initial energy distribution of the Plummer or Hernquist progenitor model. Consequently, these changes are crucial in shaping the shells. In the freefall stage following the disintegration of the progenitor potential, particles are no longer bound by self-gravity but move within the gravitational potential of the target galaxy. We investigate the relationship between the radial period and the energy of particles undergoing radial motion. We show that an accurate model of the energy range of the dwarf galaxy at disruption is essential to predict the number of observable shells.
Original languageEnglish
Article number11
Number of pages12
JournalThe Astrophysical Journal
Volume975
Issue number1
Early online date22 Oct 2024
DOIs
Publication statusPublished - 1 Nov 2024

Keywords

  • Galaxy mass distributions
  • Stellar streams
  • Astronomical simulations
  • Interacting galaxies
  • Galaxy mergers
  • Galaxy dynamics
  • N-body simulations

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