Euclid’s view of a cosmic swarm

Source: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi

The Euclid ERO image of the Perseus Cluster of galaxies contains over 1000 individual galaxies which are all orbiting each other, much like a swarm of bees. This ERO image showcases the sharpness of detail achievable with Euclid, where structures within each individual galaxy can clearly be resolved. There are approximately 100’000 additional galaxies in this image which are all further away, or “behind” the Perseus Cluster. This image is very close to the type of observation that Euclid will perform during its main science operations. By measuring the slight distortions in the shapes of these distant galaxies we can determine the amount and distribution of dark matter and shed light on the nature of the mysterious dark energy.