As the Universe evolves, gravity brings together hundreds, sometimes thousands of galaxies together to form galaxy clusters. The galaxies within these clusters usually account for about 1% of the total mass. They are encompassed by a hot low density gas (a million to 10 million Kelvin) known as the intra-cluster medium (ICM) which contains about 9% of the cluster mass. The other, approximately 90% of the mass is in the surrounding dark matter halo.

Observations at different frequencies

Observations at different frequencies help us to form a comprehensive picture of the structure and evolution of galaxy clusters. Optical telescopes, for example, can detect individual galaxies allowing us to determine the dynamics of the galaxies and infer the distribution of dark matter. X-rays observatories are used to measure thermal emission from the ICM. Radio telescopes offer a completely different view.  They detect non-thermal emission, which reveals the cluster’s magnetic field and the sites of extreme particle acceleration in the ICM.

ASTRON interests

Our group at ASTRON is interested in studying the particle acceleration processes and magnetic fields within the tenuous ICM. We wish to understand the formation of radio halos which are characterised by cluster-wide radio emission and are thought to be caused by turbulence throughout the cluster. We also aim to understand the conditions that lead to the formation of radio relics. These objects are characterised by their peripheral location and are thought to be generated by large shock waves. Finally, we are studying other unusual structures showing intense particle acceleration in the ICM and the interaction between the ICM and discrete radio sources such as tailed radio galaxies.

 

The images above show the galaxy cluster Abell 2034 in the optical, X-ray and radio. These show that the cluster contains 328 individual galaxies (including two massive brightest cluster galaxies) a disturbed ICM and several distinct sites of particle acceleration.

Research staff

Tim Shimwell

Latest tweets

Congratulations to our colleague Harish Vedantham who has been awarded a @NWONieuws #Vidi grant for his project e-MAPS! 🥳 With e-MAPS Harish will use @LOFAR to answer the question: what determines the magnetic field of an exoplanet?💫 https://bit.ly/3rekOpA

Congratulations @AstroJoeC on winning the Louise Webster prize with the discovery of Apep, a unique binary star system with the hottest stars in the Universe.

What does the start of construction of @SKAO mean for the Netherlands? Michiel van Haarlem: "we are due to take on work in the following areas: software for the calibration of data and the creation of deep sky images, " read the full interview here: https://bit.ly/3qC6yXA

Another impressive result for LOFAR! An international team of astronomers from @UniLeiden & @mediainaf discovered a galaxy that seems to be wagging it's tail, a tail of 2,5 million light years long! https://bit.ly/2QBTL9W 💫

searchtwitter-squarelinkedin-squarebarsyoutube-playinstagramfacebook-officialenvelopecrosschevron-right