Chandra telescope discovers mysterious X-ray objects that could reveal secrets of the universe

Using NASA's Chandra X-ray Observatory, scientists have discovered a new class of astronomical objects that behave in a way that is unusual for anything previously observed. These mysterious sources emit faint X-rays but also powerful ultraviolet radiation. Astrophysicists believe that these findings could help solve at least two long-standing mysteries of the universe.

A new class of “hypersoft” X-ray sources

The researchers found 84 such “hypersoft X-ray sources” in six different galaxies using publicly available data from the Chandra archive. They include the spiral galaxies M31 (Andromeda) and M101 (The Pinwheel), as well as four elliptical galaxies. These sources were seen as objects that emit brightly in the low-energy X-ray range but disappear in higher-energy images. This means that they emit significantly more low-energy X-rays than high-energy ones.

Because low-energy X-rays are located next to energetic ultraviolet radiation in the electromagnetic spectrum, researchers concluded that these sources also generate large amounts of powerful ultraviolet radiation.

Potential candidates and cosmic mysteries

The exact nature of these hypersoft X-ray sources remains unknown. However, the team of researchers believes that they are most likely associated with a black hole, neutron star or white dwarf that is dragging material from a companion star. This material heats up, producing X-rays, before falling onto the white dwarf, neutron star or black hole. Although such binary systems are known, they have never before exhibited such bright ultraviolet radiation and weak X-rays.

The discovery suggests that there may be large populations of energetic ultraviolet binary systems that have remained undetected until now. “These hidden X-ray sources are actually some of the most energetic objects in galaxies, and they could solve two cosmic mysteries at once,” said Mustafa Muhibulla, lead author of the study from the University of Alabama.

Scientists believe that some systems with white dwarfs that drag in material from companion stars may eventually explode as Type Ia supernovae. These explosions are crucial for measuring the expansion of the universe, as they helped reveal that the expansion is accelerating. Astronomers have been searching for stars that are turning into Type Ia supernovae for years, but so far without success. “If we could find a way to detect these Type Ia supernovae before they happen, that would be very important,” said study co-author Jimmy Irwin. “Now we study them after the explosion, and it’s hard for astronomers to understand what’s really going on.”

Another mystery that these hypersoft X-ray sources could solve is what exactly is stripping electrons from the gas between stars in some galaxies. This process affects the rate of star formation and determines the life cycles of galaxies. While hot, massive stars play a role, they cannot fully explain the phenomenon. The intense ultraviolet radiation from hypersoft X-ray sources could play a key role here.

These sources have been previously undetected because of their weak X-rays, which are difficult to detect, and their strong ultraviolet radiation, which is easily absorbed by the gas between stars, creating an impenetrable barrier. “By combing through the Chandra archive, we were able to eliminate what had previously been a blind spot for telescopes,” said study co-author Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics. “That’s how we found what appears to be a new class of cosmic objects with extraordinary qualities.”

Source: NASA