Astronomers find 84 hidden X-ray sources
Archival images from Chandra point to a possible new class of extremely faint but highly energetic objects.
Astronomers have found 84 remarkable sources in archival data from NASA’s Chandra X-ray telescope, located in six nearby galaxies. The study has been peer-reviewed and published in Nature Astronomy, but the nature of the objects has not yet been established.
The sources stand out because they emit mainly very low-energy X-rays. This radiation lies close to the extreme ultraviolet, a region that is difficult to study because of interstellar gas and the limitations of telescopes. As a result, objects that are energetically powerful can remain unnoticed for years in existing surveys.
The researchers call the sources ‘hypersoft X-ray sources’. They were found in six galaxies, including the Andromeda Galaxy and the Pinwheel Galaxy, as well as four elliptical galaxies. The 84 signals are not new celestial bodies that have now appeared in the sky; what is new is the recognition of a pattern in existing observations.
According to the study, the brightest sources emit approximately 10 to the power of 38 erg per second in the X-ray range examined. Models indicate that the total luminosity could be higher, because much of the energy lies outside the measured X-ray range, in ultraviolet light. These are model-based deductions, not direct measurements of the full spectrum.
The authors believe that different types of binary stars could be behind the signals. Possibilities include white dwarfs accreting matter from a companion, systems following a nova outburst and binaries containing a black hole. Here, the term ‘class’ mainly describes a shared observational pattern; it does not yet prove that all 84 sources are the same physical type of object.
The discovery could be relevant to two broader questions. Hypersoft sources may contribute to the ionisation of gas in galaxies. Some systems may also provide clues about white dwarfs that eventually become involved in type Ia supernovae. These are interesting connections, but the study does not show that these sources will cause such supernovae.
The research is peer-reviewed, but the interpretation remains provisional. New X-ray and ultraviolet observations will have to determine which objects are actually in the catalogue and whether the proposed explanations are correct. For now, the scientific significance lies mainly in a new observational category and a newly visible blind spot.
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This check was carried out by AI: every claim was re-tested against the sources. Even an approved article can contain errors — stay critical.
The numbers, telescope, publication status and main hypotheses were checked against Nature Astronomy and the Chandra team. The text avoids breakthrough language and does not present models as established explanations.
- confirmed The researchers found 84 hypersoft X-ray sources in six galaxies. — Mentioned in the Nature publication and the Chandra explanation. source
- confirmed The study was published in Nature Astronomy after peer review. — The publication includes peer-review information and a publication date. source
- confirmed The sources emit mainly radiation below 0.3 keV. — Stated in the study’s abstract. source
- confirmed White dwarfs, post-nova systems and black holes are among the proposed explanations. — Physical interpretations proposed by the authors. source
Editor's note
The publication is peer-reviewed. The 84 objects are observations from Chandra archival data; their precise nature and the proposed implications for galaxy ionisation and supernovae remain open questions for research.Sources
- Hypersoft X-ray sources as a low-energy class of luminous cosmic emitter — Nature Astronomy
- A Hidden Population of Cosmic Beacons: Discovering Hypersoft X-ray Sources with Chandra — Chandra X-ray Center
- Chandra uncovers hypersoft X-ray sources — Phys.org
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