BoRG-58: The Most Distant Galaxy Cluster

The composite image at left, taken in visible and near-infrared light, reveals the location of five galaxies clustered together just 600 million years after the Universe's birth in the Big Bang. The circles pinpoint the galaxies.

The sharp-eyed Wide Field Camera 3 aboard the NASA/ESA Hubble Space Telescope spied the galaxies in a random sky survey. The developing cluster is the most distant ever observed.

The average distance between them is comparable to that of the galaxies in the Local Group, consisting of two large spiral galaxies, the Milky Way and the Andromeda Galaxy, and a few dozen small dwarf galaxies.

The close-up images at right, taken in near-infrared light, show the galaxies. Simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical similar to the Virgo cluster's Messier 87.

Galaxy clusters are the largest structures in the Universe, comprising hundreds to thousands of galaxies bound together by gravity. The developing cluster presumably will grow into a massive galactic city, similar in size to the nearby Virgo Cluster, a collection of more than 2000 galaxies.

Photo credit: NASA, ESA, M. Trenti (University of Cambridge, UK and University of Colorado, Boulder, USA), L. Bradley (STScI), and the BoRG team

Note: For more information, see Hubble Pinpoints Furthest Protocluster of Galaxies Ever Seen.

Messier 87

This image shows the eruption of a galactic "super-volcano" in the massive galaxy M87, as witnessed by NASA's Chandra X-ray Observatory and NSF's Very Large Array (VLA). At a distance of about 50 million light years, M87 is relatively close to Earth and lies at the center of the Virgo cluster, which contains thousands of galaxies.

The cluster surrounding M87 is filled with hot gas glowing in X-ray light (shown in blue) that is detected by Chandra. As this gas cools, it can fall toward the galaxy's center where it should continue to cool even faster and form new stars.

However, radio observations with the VLA (red-orange) suggest that in M87 jets of very energetic particles produced by the black hole interrupt this process. These jets lift up the relatively cool gas near the center of the galaxy and produce shock waves in the galaxy's atmosphere because of their supersonic speed.

The interaction of this cosmic "eruption" with the galaxy's environment is very similar to that of the Eyjafjallajokull volcano in Iceland that occurred in 2010. With Eyjafjallajokull, pockets of hot gas blasted through the surface of the lava, generating shock waves that can be seen passing through the grey smoke of the volcano. This hot gas then rises up in the atmosphere, dragging the dark ash with it. This process can be seen in a movie of the Eyjafjallajokull volcano where the shock waves propagating in the smoke are followed by the rise of dark ash clouds into the atmosphere.


Video: Omar Ragnarsson

In the analogy with Eyjafjallajokull, the energetic particles produced in the vicinity of the black hole rise through the X-ray emitting atmosphere of the cluster, lifting up the coolest gas near the center of M87 in their wake. This is similar to the hot volcanic gases that drag up the clouds of dark ash. And just like the volcano here on Earth, shock waves can be seen when the black hole pumps energetic particles into the cluster gas. The energetic particles, coolest gas and shock waves are shown in a labeled version.

Photo credit: X-ray (NASA/CXC/KIPAC/N. Werner, E. Million et al); Radio (NRAO/AUI/NSF/F. Owen)