NRAO’s Karl J. Jansky Very Large Array and two of NASA’s space telescopes — Chandra X-ray Observatory and Hubble — have captured a stunning new image of MACS J0717.5+3745, a very distant and massive cluster of galaxies.

MACS J0717.5+3745 (MACS J0717 for short), also known as ClG J0717+3745, is a large galaxy cluster located in the constellation Auriga. It is approximately 5.4 billion light-years away from Earth.

According to astronomers, MACS J0717 is one of the most complex galaxy clusters known. Rather than being a single cluster, it is actually the result of four galaxy clusters colliding.

This new image of MACS J0717 contains data from three different telescopes: Hubble (showing the galaxies and stars), Chandra (diffuse emission in blue), and the Jansky Very Large Array (diffuse emission in pink). Together, these datasets produce a unique new view of MACS J0717.

The Hubble data reveal galaxies both within the cluster and far behind it.

X-rays from Chandra reveal the massive amounts of hot gas — heated to millions of degrees — that pervade the cluster.

The Jansky Very Large Array data trace the radio emission within MACS J0717, enormous shock waves – similar to sonic booms – that were triggered by the merger.

An international team of astronomers led by Dt. Reinout van Weeren from the Harvard-Smithsonian Center for Astrophysics has noted a sharp change in density on the southern edge of the cluster. This change in density is most likely caused by a collision between this cluster and a less massive structure.

In Jansky Very Large Array images of MACS J0717, seven gravitationally-lensed sources are observed, all point sources or sources that are barely larger than points. This makes MACS J0717 the cluster with the highest number of known lensed radio sources.

“All of the lensed radio sources are galaxies located between 7.8 and 10.4 billion light years away from Earth,” Dr. van Weeren and co-authors said.

“The brightness of the galaxies at radio wavelengths shows that they contain stars forming at high rates. Without the amplification by lensing, some of these radio sources would be too faint to detect with typical radio observations.”

Research on MACS J0717 was published in the February 1 issue of the Astrophysical Journal (arXiv.org preprint).

_____

R. J. van Weeren et al. 2016. The discovery of lensed radio and X-ray sources behind the Frontier Fields cluster MACS J0717.5+3745 with the JVLA and Chandra. ApJ 817, 98; doi: 10.3847/0004-637X/817/2/98