A Merger Origin for X Structures in S0 Galaxies
Abstract
Using numerical simulation, we study the response of a disk galaxy to a merger involving a low-mass satellite companion. During a prograde satellite accretion, the disk galaxy forms a strong bar in response to the perturbation of the companion. After the accretion event is over, the bar buckles vertically due to a bending instability, sending disk material well out of the disk plane. The material forms into an X-shaped feature when seen edge-on, morphologically similar to X structures observed in several S0/Sa galaxies. The mechanism described here unites previously suggested accretion and bar instability hypotheses for forming X structures into a self-consistent scenario for merger-induced formation and evolution of S0 galaxies. To complement these models, we also present observations of the peculiar S0 galaxy Hickson 87a. The thick disk, isophotal warping, and strong X structure described in the merger model are all evident in Hickson 87a, suggesting this galaxy may be an excellent example of such merger-induced galaxy evolution.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1995
- DOI:
- 10.1086/309576
- Bibcode:
- 1995ApJ...447L..87M
- Keywords:
-
- GALAXIES: EVOLUTION;
- GALAXIES: INTERACTIONS;
- GALAXIES: PECULIAR;
- GALAXIES: STRUCTURE