SIMBAD references

2006MNRAS.370..891J - Mon. Not. R. Astron. Soc., 370, 891-901 (2006/August-1)

Measurement of non-axisymmetry in centres of advanced mergers of galaxies.


Abstract (from CDS):

We measure the non-axisymmetry in the luminosity distribution in the inner few kpc of the remnants of advanced mergers of galaxies with a view to understand the relaxation in the central regions. For this, we analyse the images from the Two-Micron All-Sky Survey (2MASS) archival data for a selected sample of 12 merging galaxies, which show signs of interaction but have a single nucleus. The central regions are fitted by elliptical isophotes whose centres are allowed to vary to get the best fit. The centres of isophotes show a striking sloshing pattern with a spatial variation of up to 20-30 per cent within the central 1 kpc. This indicates mass asymmetry and a dynamically unrelaxed behaviour in the central region. Next, we Fourier-analyse the galaxy images while keeping the centre constant and measure the deviation from axisymmetry in terms of the fractional Fourier amplitudes (A1, A2, etc.) as a function of radius. All the mergers show a high value of lopsidedness (up to A1 ∼ 0.2) in the central 5 kpc. The m = 2 asymmetry is even stronger, with values of A2 up to ∼0.3, and in three cases these are shown to represent bars. The corresponding values denoting non-axisymmetry in inner regions of a control sample of eight non-merger galaxies are found to be several times smaller.

Surprisingly, this central asymmetry is seen even in mergers where the outer regions have relaxed into a smooth elliptical-like r1/4 profile or a spiral-like exponential profile. Thus, the central asymmetry is long lived, estimated to be ∼1Gyr, and hence lasts for over 100 local dynamical time-scales. These central asymmetries are expected to play a key role in the future dynamical evolution of the central region of a merger, and can help in feeding of a central active galactic nucleus.

Abstract Copyright: 2006 The Authors. Journal compilation © 2006 RAS

Journal keyword(s): galaxies: evolution - galaxies: kinematics and dynamics - galaxies: interactions - galaxies: photometry - galaxies: structure

Simbad objects: 23

goto Full paper

goto View the references in ADS

To bookmark this query, right click on this link: simbad:2006MNRAS.370..891J and select 'bookmark this link' or equivalent in the popup menu