paper

Genesis of morpho-kinematic lopsidedness in minor merger of galaxies

arXiv:2105.05270 · doi:10.1093/mnras/stac461

Abstract

An lopsided asymmetry is common in disc galaxies. Here, we investigate the excitation of an lopsidedness in host galaxies during minor mergers while choosing a set of 1:10 merger models (with varying orbital configurations, morphology of the host galaxy) from the GalMer galaxy merger library. We show that a minor merger triggers a prominent lopsidedness in stars of the host galaxy. The strength of the lopsidedness undergoes a transient amplification phase after each pericenter passage of the satellite, in concordance with past findings of exciting an lopsidedness by tidal encounters. However, once the merger happens, and the post-merger remnant readjusts itself, the lopsidedness disappears in short time-scale ( 500-850 Myr). Furthermore, a delayed merger can drive a prolonged (2 Gyr) lopsidedness in the host galaxy. We demonstrate that the lopsidedness rotates with a well-defined pattern speed which is much slower than the bar pattern speed, and is retrograde with respect to the bar. This gives rise to a dynamical scenario where the Inner Lindblad resonance of the lopsidedness falls in between the corotation and the Outer Lindblad resonance of the bar mode. A kinematic lopsidedness also arises in the host galaxy; the resulting temporal variation closely follows that of the density lopsidedness. The minor merger also triggers a transient off-centred stellar disc-dark matter halo configuration due to the tidal encounter with the satellite.

arXiv comment19 pages, 1 table, 16 figures (including appendices), accepted for publication in MNRAS

References in corpus (72)

Cited by in corpus (5)