NASA has released an absolutely beautiful photo taken by the NASA/ESA Hubble Space Telescope of PLCK G004.5-19.5, a massive cluster of galaxies in the constellation Sagittarius.
This Hubble image shows the galaxy cluster PLCK G004.5-19.5. Image credit: NASA / ESA / Hubble / RELICS / D. Coe et al.
PLCK G004.5-19.5 was discovered by ESA’s 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 the dominant object in this image, and above it a thin, curved gravitational lens arc is visible.
This is caused by the gravitational forces of the cluster bending the 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 PLCK G004.5-19.5 — 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 for even longer than that, making this image an extremely old window into the far reaches of the Universe.
This image of PLCK G004.5-19.5 was taken by Hubble’s Advanced Camera for Surveys (ACS) and Wide-Field Camera 3 (WFC3) instruments as part of an extensive observing program called Reionization Lensing Cluster Survey (RELICS).
RELICS imaged 41 massive galaxy clusters over the course of 390 Hubble orbits and 100 Spitzer Space Telescope observing hours, aiming to find the brightest distant galaxies.
Studying these galaxies in more detail with both current telescopes and the future NASA/ESA/CSA James Webb Space Telescope will hopefully tell us more about our cosmic origins.
