Astronomers have mapped out half the universe in X-ray light, using a space telescope called eROSITA. The new map, which contains almost a million X-ray sources, is the basis of dozens of new scientific papers, with many more to come.
eROSITA is a soft X-ray imaging telescope positioned at Lagrange Point 2, making it a neighbor of the James Webb Space Telescope. The goal was to perform a scan of the entire sky at X-ray wavelengths, to detect new galaxies, clusters, supermassive black holes and other objects, as well as study gigantic structures and help to measure dark energy, the mysterious force that’s accelerating the expansion of the universe.
This first official data release is known as the eROSITA All-Sky Survey Catalogue (eRASS1), which is built from data gathered by the telescope between December 12, 2019 and June 11, 2020. In that time, eROSITA was able to capture 170 million individual X-ray photons, and by measuring the energy and arrival time of each one, a detailed map of the cosmos can be built.
In this case, the map covers half of the night sky – the western hemisphere – and contains over 900,000 X-ray sources. That includes about 710,000 supermassive black holes that are chowing down on matter at the center of galaxies, 180,000 X-ray-emitting stars in the Milky Way, and 12,000 galaxy clusters, as well as a few less common objects like pulsars, supernova remnants, binary stars, and other X-ray sources.
“These are mind-blowing numbers for X-ray astronomy,” said Andrea Merloni, eROSITA principal investigator. “We’ve detected more sources in six months than the big flagship missions XMM-Newton and Chandra have done in nearly 25 years of operation.”
This first big public release of the data is accompanied by almost 50 newly published papers based on eRASS1. That includes the discovery of over 1,000 galaxy superclusters, as well as a 42 million light-year-long filament of gas connecting two clusters, how X-ray emissions from stars may affect their planets’ habitability, and studies of X-rays from supernova remnants, stars, and other objects.
And of course, this is just the beginning. eROSITA made three further scans of the sky between June 2020 and February 2022, when the joint German-Russian project was put on hold due to the Russian invasion of Ukraine. The data from those later scans will be released in the near future.
The full list of scientific publications based on the data can be found on the eROSITA website.
Source: Max Planck Institute
