A composite image of the giant elliptical galaxy NGC 4649 located about 51 million light years from Earth. It contains one of the biggest black holes in the local Universe: its mass is about 3.4 billion times that of the Sun.
The elliptical galaxy NGC 1399 in the Fornax galaxy cluster. (via Chandra)
High-resolution, very deep colour image of a field in the South of the Centaurus A galaxy halo. (via ESO)
This composite image shows the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell 520, formed from a violent collision of massive galaxy clusters that is located about 2.4 billion light years from Earth. (via Chandra)