Galaxy groups and clusters

Galaxy groups and clusters are fantastic laboratories in/with which study a broad range of exciting astrophysics and cosmology. The number, mass, and internal structure of groups and clusters are sensitive to the physics of the mysterious dark matter and dark energy that dominate the mass-energy content of the universe. They are also a key venue for the evolution of galaxies, including probing the physics responsible for quenching star formation as galaxies and groups of galaxies travel along filaments towards larger structures including massive clusters. The cores of groups and clusters can also be dense enough to act as powerful cosmic magnifying glasses via the phenomenon of strong gravitational lensing.

Our team

Academics: Dr Sean McGeeProfessor Graham Smith
Fellows: Dr Matteo Bianconi, Dr Dan Ryczanowski

Groups and clusters at Birmingham

We are interested in galaxy groups and clusters as special locations within the large scale structure of the universe that shape the evolution of galaxies, and boost the sensitivity of our telescopes via gravitational lensing, especially in the context of multi-messenger astronomy. For example, together with Dr Andrew Robertson we showed that around half of the gravitational lensing in the universe is "done" by groups and clusters of galaxies. This shapes our contributions to the Strong Lensing Science Collaboration, including building infrastructure for the routine detection of gravitationally lensed transients with the Vera Rubin Observatory, and designing multi-messenger gravitational lensing discovery strategies.

We also have a long-standing interest in strong and weak gravitational lensing as probes of the largescale structure of the universe, and in particular the mass and structure of galaxy clusters. The Birmingham-led Local Cluster Substructure Survey (LoCuSS) played an important role in the emergence of multi-wavelength gravitational lensing (2005-2020). We built a unique dataset on local galaxy clusters that enabled a wide range of "firsts" in galaxy cluster astrophysics and cosmology, many of which were led by early career researchers. A curated list of LoCuSS publications is available.

LoCuSS built on, and benefitted hugely from, a rich legacy of X-ray observations of galaxy groups and clusters by Birmingham astronomers, many of which were led by Professor Trevor Ponman. This programme grew from the Birmingham Astrophysics and Space Research Group's roles in the construction of the ROSAT and XMM-Newton X-ray satellites, which helped to launch Extragalactic Astronomy in Birmingham.