The central region of the cluster can be seen glowing brightly, with its diffuse outer regions extending outwards from the middle of the frame. Perseus’ density rises quickly as one approaches the cluster’s cool centre; this is reflected in its X-ray brightness, which changes rapidly with radius (as illustrated by the colouring of this image).
The overlaid blue and red arrows show the motion of the gas in the region (relative to the cluster itself), with blue arrows representing gas moving towards us, and red representing gas moving away. The length of the ‘tail’ on the arrows represents the size of the velocity: the longer the arrow tail, the faster the gas is moving.
This image is part of a new study of Perseus that spotted the first signs of this gas splashing and sloshing around – a behaviour that, while predicted, had never been seen before.