Multi-band images of the very isolated spiral galaxy NGC 5523 show a number of unusual features consistent with NGC 5523 having experienced a significant merger: (1) Near-infrared (NIR) images from the Spitzer Space Telescope (SST) and the WIYN 3.5-m telescope reveal a nucleated bulge-like structure embedded in a spiral disk. (2) The bulge is offset by ~1.8 kpc from a brightness minimum at the center of the optically bright inner disk. (3) A tidal stream, possibly associated with an ongoing satellite interaction, extends from the nucleated bulge along the disk. We interpret these properties as the results of one or more non-disruptive mergers between NGC 5523 and companion galaxies or satellites, raising the possibility that some galaxies become isolated because they have merged with former companions.
@article{arxiv.1611.05968,
title = {NGC 5523: An Isolated Product of Soft Galaxy Mergers?},
author = {Leah M. Fulmer and John S. Gallagher and Ralf Kotulla},
journal= {arXiv preprint arXiv:1611.05968},
year = {2017}
}