The galaxy shows off an unusual ring in x-rays

The galaxy shows off an unusual ring in x-rays

X-ray overview of the Chandra telescope (violet) combined with optical data of the Hubble Space Telescope (red, green and blue)

Scientists took advantage of NASA's Chandra X-ray Observatory and found a ring from black holes or neutron stars in a galaxy that is 300 million light years away from us. No, you should not equip hobbits and wander around Middle-earth. But this space formation is important for researchers who are trying to understand what happens during large-scale collisions of galaxies.

This image shows the galaxy AM 0644-741 (AM 0644). For the display, a review of the Chandra X-ray data (purple) and the optical information of the Hubble Space Telescope (red, green, and blue) were combined. Chandra shows incredibly bright sources of X-rays, activated by a stellar-mass black hole or a ring-shaped neutron star.

Where did this ring come from in AM 0644? Astronomers believe that it was formed when one galaxy was attracted by the second force of gravity. The first created ripples in the second gas (AM 0644), located at the bottom right. Then a ripple produced an expanding gas ring in AM 0644, which caused the birth of new stars. Perhaps the first galaxy is in the lower left corner.

The galaxy shows off an unusual ring in x-rays

X-ray wavelength image

The most massive stars will not live long (millions of years). As soon as they run out of nuclear fuel, they explode as supernovae, leaving behind black holes with masses 5-20 times larger than solar or neutron stars (almost equal to solar mass). Some black holes or neutron stars have close satellites or an approximate siphon gas from a stellar partner. This gas flows to the object, forming a rotating disk, heated by friction. The superheated gas then creates a huge amount of X-ray radiation that Chandra sees.

The ring of a black hole or neutron stars intrigues by itself, but in the history of AM 0644 there is more. All X-ray sources found in the ring are bright enough to be classified as ultra-bright X-ray sources (ULX). This is a category of objects that create hundreds or thousands of times more X-rays than most of the “normal” binary systems. Earlier it was believed that such objects include the presence of black holes of average mass, but this was refuted when neutron stars were detected in galaxies M82 and M51.

The galaxy shows off an unusual ring in x-rays

Optical Image

Identification of individual ULX in the galaxy is not yet possible. They can be a mixture of black holes and neutron stars, or they are all just black holes or neutron stars. It is also important to understand that not all X-ray sources in the image belong to the ring in AM 0644. One of them is a fast-growing black hole living at a distance of 9.1 billion light years from us. There is also a supermassive black hole located in the galactic center. Ring galaxies attract the attention of researchers, as they will allow a better understanding of the formation of binary stars and the origin of ULX.

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