Spitzer/Infrared Array Camera near-infrared features in the outer parts of S4G galaxies

Seppo Laine, Johan H. Knapen, Juan Carlos Muñoz-Mateos, Taehyun Kim, Sébastien Comerón, Marie Martig, Benne W. Holwerda, E. Athanassoula, Albert Bosma, Peter H. Johansson, Santiago Erroz-Ferrer, Dimitri A. Gadotti, Armando Gil De Paz, Joannah Hinz, Jarkko Laine, Eija Laurikainen, Karín Menéndez-Delmestre, Trisha Mizusawa, Michael W. Regan, Heikki SaloKartik Sheth, Mark Seibert, Ronald J. Buta, Mauricio Cisternas, Bruce G. Elmegreen, Debra M. Elmegreen, Luis C. Ho, Barry F. Madore, Dennis Zaritsky

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)3015-3039
Number of pages25
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Mar 19 2014


  • Atlases - catalogues - galaxies
  • Galaxies
  • Interactions - galaxies
  • Peculiar - galaxies
  • structure - infrared

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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