The name of this galaxy cluster is PLCK G004.5-19.5. You may not think the name is very creative, but it did remind me of a paper: Strong Lensing Analysis of PLCK G004.5-19.5, a Planck-Discovered Cluster Hosting a Radio Relic at z=0.52. Thanks Hubble it was very useful.
Heh, I remember the paper because of a happy coincidence. About a week ago I happened to be doing some housekeeping on this computer and that was one of the files – and I didn’t delete it.
ESA — This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster PLCK G004.5-19.5. It was discovered by the ESA Planck satellite through the Sunyaev-Zel’dovich effect — the distortion of the cosmic microwave background radiation in the direction of the galaxy cluster by high-energy electrons in the intracluster gas. The large galaxy at the center is the brightest galaxy in the cluster, and above it a thin, curved gravitational lens arc is visible. This arc is caused by the gravitational forces of the cluster bending the path of light from stars and galaxies behind it, in a similar way to how a glass lens bends light.
Several stars are visible in front of the cluster — recognizable by their diffraction spikes — but aside from these, all other visible objects are distant galaxies. Their light has become redshifted by the expansion of space, making them appear redder than they actually are. By measuring the amount of redshift, we know that it took more than 5 billion years for the light from this galaxy cluster to reach us. The light of the galaxies in the background had to travel even longer than that, making this image an extremely old window into the far reaches of the universe.
This image was taken by Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) as part of an observing program called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA James Webb Space Telescope to study.
Credit: ESA/Hubble & NASA, RELICS; Acknowledgement: D. Coe et al.
Text: European Space Agency