Vol. 574
In section 3. Cosmology

Witnessing a merging bullet being stripped in the galaxy cluster RXCJ2359.3-6042

Galaxy cluster mergers are precious events. They enlighten cluster formation physics, and provide an opportunity to constrain the nature of dark matter. The Bullet cluster is the most famous example, but more cases to study would be welcome. The authors have discovered another bullet, crossing the Abell 4067 cluster at redshift z=0.0992. The small intruder is compact and goes right through the central region of Abell 4067 without being disrupted. It is possible to follow its gas trail as the bullet is stripped of its outer layers. There is an indication of a shock heated region of the large cluster with a higher temperature. The infalling bullet must have induced a mild shock, as shown by the wide angle. It is therefore a much less energetic collision than the Bullet cluster.