Scientists have found four enormous cavities, or bubbles, at the center of a galaxy cluster using NASA’s Chandra X-ray Observatory. This unusual set of features may have been caused by eruptions from two supermassive black holes closely orbiting each other.

Galaxy clusters are the largest structures in the universe held together by gravity. They are a mixture of hundreds or even thousands of individual galaxies, enormous amounts of hot gas, and unseen dark matter. The hot gas that pervades clusters contains much more mass than the galaxies themselves, and glows brightly in X-ray light that Chandra detects. An enormous galaxy is usually found at the center of a cluster.

A new Chandra study of the galaxy cluster known as RBS 797, located about 3.9 billion light-years from Earth, uncovered two separate pairs of cavities extending away from the center of the cluster.

Did black holes form immediately after the Big Bang? How did supermassive black holes form? What is dark matter? In an alternative model for how the Universe came to be, as compared to the ‘textbook’ history of the Universe, a team of astronomers propose that both of these cosmic mysteries could be explained by so-called ‘primordial black holes’. In the graphic, the focus is on comparing the timing of the appearance of the first black holes and stars, and is not meant to imply there are no black holes considered in the standard model. Credit: ESA.

The European Southern Observatory’s Very Large Telescope Interferometer (ESO

Created in 1962, the European Southern Observatory (ESO), is a 16-nation intergovernmental research organization for ground-based astronomy. Its formal name is the European Organisation for Astronomical Research in the Southern Hemisphere.

In this work we propose a novel campaign for constraining relativistically compact MACHO dark matter, such as primordial black holes (PBHs), using the moon as a detector. PBHs of about $10^{19} \textrm{ g}$ to $10^{22} \textrm{ g}$ may be sufficiently abundant to have collided with the moon in the history of the solar system. We show that the crater profiles of a PBH collision differ from traditional impactors and may be detectable in high resolution lunar surface scans now available. Any candidates may serve as sites for in situ measurements to identify high pressure phases of matter which may have formed near the PBH during the encounter. While we primarily consider PBH dark matter, the discussion generalises to the entire family of MACHO candidates with relativistic compactness.