Scientists reveal what the sky looks like in X-ray vision: ScienceAlert

Scientists reveal what the sky looks like in X-ray vision: ScienceAlert

There’s an old saying in science fiction about someone suddenly getting x-ray vision and looking through solid objects. It turns out that’s physically impossible with our Mark I eyeballs. However, astronomers have found a way to overcome this challenge that allows us to study the universe through X-ray vision.

It’s called X-ray astronomy and it’s been around for 60 years. It reveals some of the most active and violent events and objects in the universe. This includes things like bright quasars, supernova explosions, streams of hot intergalactic gas, and hot young stars.

Recently, astronomers in the eROSITA consortium at the Max Planck Institute for Extraterrestrial Physics announced the latest set of X-ray data from the eROSITA survey. It covers half the X-ray sky and reveals information about 900,000 different X-ray sources.

That’s more than anything ever discovered in the decades of X-ray astronomy, including discoveries made with Chandra and other orbiting observatories.

Circular view of Earth's sky in X-rays.
This image shows half of the sky in X-rays, projected onto a circle with the center of the Milky Way on the left and the galactic plane running horizontally. Photons are color-coded according to their energy (red for 0.3-0.6 keV, green for 0.6-1 keV, blue for 1-2.3 keV). (MPE, J. Sanders/eROSITA Consortium)

About Erosita

eROSITA is a soft X-ray imaging telescope on board the Spectrum-RG satellite. The first sky survey, called eRASS1, was conducted over a 7-month period starting on December 12, 2019.

At its most sensitive setting, the telescope detected 170 million X-ray photons. This allowed the cameras to measure their energies and arrival times.

The astronomy team, led by principal investigator Andrea Merloni, has compiled the data catalog for the first time. They also published more than 50 new scientific papers based on their findings.

After completing this first survey, the instrument conducted three more scans of the entire sky between June 2020 and February 2022. This huge trove of X-ray data will be released soon. The video below explains more about the mission.

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eROSITA cabinet for X-ray sources

X-ray astronomy focuses on hot, energetic objects and events in the universe. These could be galactic centers (where supermassive black holes lurk), supernova explosions, newborn stars, and other places where matter is heated to high temperatures.

This initial eRASS1 dataset identifies approximately 710,000 supermassive black holes, 180,000 X-ray-emitting stars in the Milky Way, and 12,000 galaxy clusters. It also covers a small number of other exotic sources such as X-ray emitting binary stars, supernova remnants, pulsars, and other objects.

“These are amazing numbers for X-ray astronomy,” says Andrea Merloni, eROSITA’s principal investigator and first author of the eROSITA catalog paper. “We have discovered more sources in 6 months than the two large mainline missions XMM-Newton and Chandra have in their nearly 25 years of work.”

The first release of eROSITA data is a rich, “layered” view of the sky at many X-ray energies. Each energy level tells astronomers something about the objects and events that emit X-rays. For each set of images and data, the consortium provides more information.

There are lists of source categories, sky locations, energies, and exact arrival times of photons to the instrument.

“We have put a lot of effort into producing high-quality data and software,” added Miriam Ramos Ceja, who leads the eROSITA operations team. “We hope this will expand the base of scientists around the world working with high-energy data and help push the boundaries of X-ray astronomy.”

Cutouts show details in X-ray views of Earth's sky
An eROSITA X-ray image showing the newly discovered filament between two galaxy clusters. The distribution of galaxies (white lines, top left), as seen from the Two Micron All Sky Survey, follows a filament structure. In the slow simulation, which was designed to reproduce key features of the local universe, this single system was also reproduced with both clusters and a stringy backbone. (Dietl et al. 2024)

Focus on specific objects from x-rays

The scientific goals of eROSITA are to use X-rays as a means of detecting the hot intergalactic medium containing 50 to 100,000 clusters and clusters of galaxies. It also looks at the hot gas in the filaments between them. These filaments glow in X-rays.

The instrument is also tasked with detecting accreting black holes hidden in galaxies. Finally, he studied the physics of galactic X-ray sources (which include pre-main sequence stars, supernova remnants, and X-ray binaries).

At least one of the papers released with the new survey data uses X-ray data to constrain cosmological models that use clusters of galaxies. In one of the published images, we see strands of newly discovered material.

It extends between one part of the galactic cluster Abell 3667 and the neighboring cluster Abell 3651. This may help astronomers determine the amount of matter present in the so-called “warm and hot galactic medium.” It gives insight into the formation of large-scale structures (such as galaxy clusters) in the universe.

The nearby Virgo galaxy cluster is also visible in the eRASS1 survey and provides a way to study large-scale filamentary structures. In particular, astronomers want to understand the physical effects that occur on the outskirts of these massive galaxy clusters.

Using the new survey data, as well as other images of the entire sky, a scientific team discovered the structure of the cluster’s suburbs. This included high-energy emissions around galaxies and clusters within the cluster. They also studied a so-called “X-ray spillover” 320 kiloparsec long near the galaxy M49.

A clip showing the details of the Virgo Cluster in X-rays
This X-ray image shows the full extent of the Virgo cluster in X-rays as seen by eROSITA. The bright white spot in the center is the central galaxy M87. The hazy white glow around M87 is very hot intergalactic gas. It extends in some directions more than others, and is not circular. This is evidence that the Virgo group is still in the process of being formed. (McColl al. 2024)

eROSITA’s past and future work

eROSITA has enabled a huge leap forward in X-ray astronomy since its launch in June 2019. It began operations in October of that year, providing a high-resolution X-ray view of the universe. As he scanned the sky, I glimpsed changes in a distant quasar SMSS called J114447.77-430859.3.

These changes give some evidence of black hole growth at the core of the quasar. Changes in brightness variations were observed in the core of the quasar, indicating that the black hole is swallowing some of the material moving away in its event horizon. Other materials escape in the form of strong winds.

The instrument also detected a newly formed black hole in the early universe, and tracked the presence of hot gas throughout our Milky Way Galaxy. The device was first turned on on October 22, 2019. It is currently in safe mode and technicians are assessing its health and condition.

This article was originally published by Universe Today. Read the original article.

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