Document Type

Article

Publication Date

11-2014

Department

Physics and Astronomy

Abstract

We present a catalogue and images of visually detected features, such as asymmetries, extensions, warps, shells, tidal tails, polar rings, and obvious signs of mergers or interactions, in the faint outer regions (at and outside of R25) of nearby galaxies. This catalogue can be used in future quantitative studies that examine galaxy evolution due to internal and external factors. We are able to reliably detect outer region features down to a brightness level of 0.03 MJy sr−1 pixel−1 at 3.6 μm in the Spitzer Survey of Stellar Structure in Galaxies (S4G). We also tabulate companion galaxies. We find asymmetries in the outer isophotes in 22 ± 1 per cent of the sample. The asymmetry fraction does not correlate with galaxy classification as an interacting galaxy or merger remnant, or with the presence of companions. We also compare the detected features to similar features in galaxies taken from cosmological zoom re-simulations. The simulated images have a higher fraction (33 per cent) of outer disc asymmetries, which may be due to selection effects and an uncertain star formation threshold in the models. The asymmetries may have either an internal (e.g. lopsidedness due to dark halo asymmetry) or external origin.

Comments

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society Copyright: 2014. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

https://doi.org/10.1093/mnras/stu1642

Original Publication Information

Laine, Seppo, et al. "Spitzer/Infrared Array Camera Near-Infrared Features in the Outer Parts of S4G Galaxies." 2014. Monthly Notices of the Royal Astronomical Society 444(4): 3015-3039.

DOI

10.1093/mnras/stu1642

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