Details

Autor(en) / Beteiligte

• Melnyk, O.
• Mitronova, S.
• Karachentseva, V.

Titel

Colours of isolated galaxies selected from the Two-Micron All-Sky Survey

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2014-02, Vol.438 (1), p.548-556

Ort / Verlag

London: Oxford University Press

Erscheinungsjahr

2014

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The properties of isolated galaxies are driven mainly by intrinsic evolution and not by the external influence of their environments. Therefore, the sample of isolated galaxies can be considered as a reference sample to study different environmental effects. We have made detailed comparisons between the near-infrared (Two-Micron All-Sky Survey, 2MASS) and optical (Sloan Digital Sky Survey, SDSS) colours of the 2MASS Isolated Galaxies (2MIG) sample selected from the 2MASS Extended Source Catalogue and with other objects from the wide range of denser environments (field, groups/clusters, triplets and pairs). We have found that early-type galaxies show similar (J − H)rest and (g − r)rest colours in practically all types of environments, except for the massive early-type galaxies located in compact pairs with high velocity difference (dV ∼ 180 km s−1), which are significantly redder and brighter than isolated galaxies. We assume that these pairs are located in the centres of more populated groups and clusters. In general, galaxies in groups and pairs of spiral and late morphological types have redder near-infrared colours (J − H)rest than 2MIG isolated galaxies. The (g − r)rest colours of galaxies in groups and pairs with high velocity difference are also significantly redder than the corresponding colours of 2MIG isolated galaxies. In contrast, the members of most compact pairs (dV ∼ 50 km s−1, R ∼ 30 kpc) show the same (g − r)rest colour and even tend to be bluer than 2MIG isolated galaxies. In summary, our results show that the colours of galaxies depend very much on external factors.