Lopsidedness and Sloshing in Centres of Advanced Mergers of Galaxies

TL;DR

This study analyzes the central regions of advanced galaxy mergers, revealing persistent asymmetries and sloshing patterns that influence their evolution and active galactic nuclei fueling.

Contribution

It provides the first detailed measurement of central lopsidedness and sloshing in galaxy mergers using 2MASS data, highlighting their long-lived nature.

Findings

High central asymmetry with up to 30% variation within 1 kpc

Fourier lopsidedness amplitude up to 0.2 within 5 kpc

Asymmetries last for several billion years, affecting galaxy evolution

Abstract

We measure the non-axisymmetry in the luminosity distribution in the central few kpc of a sample of advanced mergers of galaxies, by analyzing their 2MASS images. All mergers show a high central asymmetry: the centres of isophotes show a striking sloshing pattern with a spatial variation of upto 30 % within the central 1 kpc; and the Fourier amplitude for lopsidedness (m=1) shows high values upto 0.2 within the central 5 kpc. The central asymmetry is estimated to be long-lived, lasting for ~ a few Gyr or ~ 100 local dynamical timescales. This will significantly affect the dynamical evolution of this region, by helping fuel the central active galactic nucleus, and also by causing the secular growth of the bulge driven by lopsidedness.