Free Access
Volume 565, May 2014
Article Number A25
Number of page(s) 31
Section Extragalactic astronomy
Published online 28 April 2014

Online material

Appendix A: Far-infrared galaxy morphologies

In this section we present the Spitzer/IRAC “true” colour images of the HCGs in our sample, overlaid with the Herschel/SPIRE 250 μm cold dust contours in green, as well as with the atomic gas contours (in red; where available). We convolved the Herschel/PACS and SPIRE bands to the beam of SPIRE 500 μm and compared them to each other to eliminate background sources and mapping artefacts. Therefore, all dust contours observed in these maps are correlated with the groups.

When examining these maps one can notice extended dust features (i.e. in HCG4, HCG22, and HCG47) and tidal dust bridges (such as the one connecting HCG95C and HCG95A, observed in all bands from the UV to the sub-mm). On the other hand, cases such as HCG22a and HCG68b where their stellar disk extends more than their dust could imply the truncation of the outer dust layers due to tidal stripping. Finally, there are extreme cases, such as HCG92 where all the gas and almost all the dust are located in a large dusty filament outside the main bodies of the galaxies.

thumbnail Fig. A.1

True colour images, created using the 3.6, 4.5 and 8.0 μm Spitzer/IRAC mosaics of all the groups in our sample. The green and red (when available) contour maps are the 250 μm Herschel/SPIRE and the VLA/HI moment-0 maps of the same groups. The six contours correspond to 3, 5, 7, 9, and 20σ. In the bottom right corner of each panel we present the size of the SPIRE 250 μm and VLA band beams, respectively. The RA and Dec scales of the axes are in J2000.0 coordinates.

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© ESO, 2014

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