Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2011-06-14
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
26 pages, 13 figures. Accepted for publication in Astronomy and Astrophysics
Scientific paper
Using stellar-dynamical calculations it is shown for the first time that counter-orbiting material emerges naturally in tidal interactions of disc galaxies. Model particles on both pro- and retrograde orbits can be formed as tidal debris in single encounters with disc galaxies of 1-to-1 and 4-to-1 mass ratios. A total of 74 model calculations are performed for a range of different initial parameters. Interactions include fly-by and merger cases. The fraction of counter-orbiting material produced varies over a wide range (from a few up to 50 percent). All fly-by models show a similar two-phase behaviour, with retrograde material forming first. Properties of the prograde and retrograde populations are extracted to make an observational discrimination possible. During such encounters the tidal debris occupies a certain region in phase space. In this material, tidal-dwarf galaxies may form. The modelling therefore can explain why galaxies may have dwarf galaxies orbiting counter to the bulk of their dwarf galaxies. An example is the Sculptor dwarf of the Milky Way, which orbits counter to the bulk of the disc of satellites. The modelling thus supports the scenario of the MW satellites being ancient tidal-dwarf galaxies formed from gaseous material stripped from another galaxy during an encounter with the young MW. A possible candidate for this galaxy is identified as the Magellanic Cloud progenitor galaxy. Its angular motion fits the angular motion of the MW disc of satellites objects. This scenario is in agreement with Lynden-Bell's original suggestion for the origin of the dSph satellites and the near-unbound orbit of the LMC.
de Boer Klaas. S.
Kroupa Pavel
Pawlowski Marcel S.
No associations
LandOfFree
Making Counter-Orbiting Tidal Debris: The Origin of the Milky Way Disc of Satellites does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Making Counter-Orbiting Tidal Debris: The Origin of the Milky Way Disc of Satellites, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Making Counter-Orbiting Tidal Debris: The Origin of the Milky Way Disc of Satellites will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-114459