Double-nucleus elliptical MCG-01-12-005 in an X-ray emitting cluster of galaxies
Journal
Date Issued
2015
Author(s)
Description
We thank the Asiago and Loiano Observatories Time Allocation Committes for the allocated telescope times; Roberto Gualandi (Loiano) and Paolo Ochner (Asiago) for making the observations in service mode. We thank the anonymous referee for useful suggestions.
Abstract
The scenario of galaxy formation is believed to follow a structure that builds up from the bottom, with large galaxies being formed by several merging episodes of smaller ones. In this scenario a number of galaxies can be expected to be seen in the merging phase, with their external regions already mixed, while their nuclei, with stronger self-gravitation, are still recognizable as such. During a photometric monitoring of active galactic nuclei (AGNs) in the field of a long-exposure INTEGRAL pointing, we serendipitously found an elliptical galaxy in the center of the X-ray cluster (EXO 0422-086) with two nuclei. We performed surface photometry on our images and those of the SDSS archive and obtained slit spectra of both nuclei. Aperture photometry of the two stellar-like nuclei showed very similar colors in the SDSS image and in our Johnson BVRI images, which is typical of an elliptical galaxy nucleus. The spectra of the nuclei showed the typical absorption lines of an elliptical galaxy without appreciable emission lines. The redshifts derived from each nucleus were equal and fully consistent with the literature value (0.0397). We can therefore exclude the possibility that one of the nuclei is a foreground star or a background AGN and consider this elliptical galaxy as a bona fide example of a galaxy merger.
Volume
576
Start page
A124
Issn Identifier
0004-6361
Ads BibCode
2015A&A...576A.124N
Rights
open.access
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