Featured Image: A Collection of Galaxy Clusters

grid of 20 images of galaxy clusters with contours indicating mass, distance from the brightest cluster galaxy, and magnification

Composite-color images of 20 of the galaxy clusters from the study. The contour lines show levels of mass density (white), magnification (cyan), and distance from the brightest galaxy in the cluster (green). Click for the high-resolution version. [Fox et al. 2022]

The points of light in the images above and to the right are not stars but rather galaxies in distant galaxy clusters — the largest gravitationally bound structures in the universe. These clusters are so massive that they can act as gravitational lenses, bending the light from background objects into arcs and circles. Comparisons of observations and cosmological models reveal that we see far more galaxies distorted into arcs than predicted, suggesting that we don’t yet fully understand the connections between the properties of a galaxy cluster, its ability to lens distant objects, and cosmology. In a new article, a team led by Carter Fox (University of Michigan) studied dozens of galaxy clusters to understand the connection between the properties of a cluster and its lensing strength. Fox and collaborators identified properties that correlate with the cluster’s lensing strength, like the amount of mass concentrated near the cluster’s brightest galaxy. The team’s results should guide the search for galaxy clusters with strong lensing properties, helping astronomers study galaxies in the early universe and constrain cosmological models. To learn more about how astronomers study gravitational lensing, check out the full article below.


“The Strongest Cluster Lenses: An Analysis of the Relation between Strong Gravitational Lensing Strength and the Physical Properties of Galaxy Clusters,” Carter Fox et al 2022 ApJ 928 87. doi:10.3847/1538-4357/ac5024