Astronomers have made an intriguing claim suggesting that the presence of a sun-like star orbiting a small black hole might actually indicate the existence of a boson star—an exotic celestial object composed entirely of dark matter.
The Gaia survey, led by the European Space Agency, provided detailed maps of over a billion stars in the Milky Way galaxy. While the majority of these stars exhibited expected behavior, some surprising anomalies were discovered. Notably, one star was observed orbiting a dark companion.
The star itself appeared fairly typical, with a mass of 0.93 times that of our sun and a chemical composition similar to our own. However, its companion emitted no detectable radiation. The prevailing hypothesis among astronomers was that the companion was a black hole, which could plausibly account for the observed phenomena.
However, a team of astronomers recently published a paper on the arXiv preprint server, highlighting the highly unusual nature of this particular configuration. Black holes typically originate from the deaths of extremely massive stars, making it improbable for a star like our sun to form as part of a binary pair with such a massive star. The authors argue that this scenario requires a significant level of fine-tuning, prompting them to suggest alternative possibilities.
One of the most exotic propositions put forward is that the dark companion is not a black hole, but rather a boson star. Boson stars are hypothetical objects associated with a particular form of dark matter. Dark matter comprises more than 80% of the total mass in every galaxy and is composed of an as-yet-undiscovered particle that eludes current scientific understanding. In some theories, these particles are bosons, similar to photons and gluons, which are particles that typically mediate fundamental forces. However, dark matter bosons would possess distinct characteristics, essentially permeating the universe and constituting its predominant mass.
Due to their nature, boson particles of dark matter could accumulate and condense, forming dense and compact objects. These objects would emit no observable radiation and would appear to external observers to behave similarly to black holes.
While the discovery of a boson star through this observation remains highly unlikely, the idea is worth considering for two key reasons. Firstly, the star is unequivocally orbiting a small, dense, and compact object, providing an ideal environment for testing our understanding of gravity as described by Einstein’s general theory of relativity. Any inconsistencies between theoretical predictions and observational data would be a groundbreaking discovery.
Secondly, this situation serves as a case study for exploring the nature of boson stars. Researchers can investigate the properties of these hypothetical and exotic objects, utilizing this scenario as a means to test theoretical ideas. Although it is improbable that these tests will provide evidence in favor of boson stars’ existence, every bit of knowledge gained about dark matter— even if it involves a gradual process of ruling out intriguing concepts—contributes to our overall understanding.