A Merger Origin for X-Structures in S0 Galaxies

Chris Mihos; Ian Walker; Lars Hernquist; Claudia Mendes de Oliviera; Mike Bolte

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A Merger Origin for X-Structures in S0 Galaxies

Chris Mihos·Ian Walker·Lars Hernquist·Claudia Mendes de Oliviera·Mike Bolte

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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.

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Chris Mihos, Ian Walker, Lars Hernquist, Claudia Mendes de Oliviera, Mike Bolte. 1995-04-26. A Merger Origin for X-Structures in S0 Galaxies. https://arxiv.org/abs/astro-ph/9504094

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