Massive Cluster Galaxies Move in Unexpected Ways

MS0440+02 galaxy cluster. The central galaxy is a multi-component BCG formed by six bright elliptical spheroids, all at the same redshift. This is a color composite GMOS South image (g, r, i) of the clusters. The size of the image is 2.6 x 2.6 arcmin2 (N up, E left). Credit: R. Carrasco (Gemini Observatory/AURA) and Tomás Verdugo (UNAM).

Astronomers using data from both of the Gemini Multi-Object Spectrographs (GMOS - North and South) measured the motions of stars within a sample of 32 massive elliptical cluster galaxies and found the stellar motions inconsistent with these galaxies’ solitary cousins. For more see the Web Feature.