Far-infrared emission from Shakhbazian Compact Galaxy Groups

Abstract

Using the IRAS archives, we searched for far-infrared (FIR) counterparts of Shakh bazian Compact Groups of Galaxies (SCGGs). Reliable IRAS detections are identified at the positions of 24 out of 367 SCGGs; another 10 IRAS sources, located within ~2 arcmin of SCGGs, are possibly associated with the corresponding galaxy groups. Some of these sources are not very reliable. Previous work has shown that the fraction of E and S0 galaxies in a representative sample of SCGGs is 77%, while E and S0 galaxies comprise about 51% of galaxies in Hickson Compact Groups (HCGs). The higher fraction of early Hubble types, combined with their greater distances, explains the low IRAS detection rate of SCGGs (7-8%) compared to HCGs (64%). The FIR colors and morphological types of galaxies in the groups suggest that active star formation or Seyfert galaxies may be the main source of the FIR emission in the SCGGs detected by IRAS, perhaps originating as the result of tidal interactions in the dense environments of these groups.

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