DATE2026.01.28 #Press Releases
Observing Dark Energy Using Black Holes as Detectors
-A New Astronomical Method for Measuring Cosmic Birefringence-
Summary
Fumihiro Naokawa, a graduate student at the Graduate School of Science, the University of Tokyo, has investigated new ways to overcome a major challenge in observing a phenomenon known as cosmic birefringence—namely, systematic errors originating from the telescope itself.
As a result, he has developed a novel method that uses specific classes of astrophysical objects, such as radio galaxies powered by supermassive black holes, to test the phenomenon through an approach fundamentally different from conventional techniques. This new method opens up the possibility of probing the true nature of dark energy.
This research provides a way to simultaneously resolve multiple issues associated with measurements of cosmic birefringence based on observations of the cosmic microwave background (CMB). The proposed method could be realized in the near future by observing black holes across the Universe using large-scale international radio astronomy facilities.
If the theoretically predicted signal is detected, it would not only confirm the existence of cosmic birefringence but also constitute evidence for dark energy. Conversely, if no such signal is observed, the results would place constraints on theoretical models of cosmic birefringence and dark energy.
Figure：Conceptual illustration of the rotation induced by cosmic birefringence on the light from the cosmic microwave background (CMB) and astrophysical sources (Credit: Naokawa, higgstan.com)
Links
Journals
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Journal name Physical Review LettersTitle of paper Universal profile for cosmic birefringence tomography using radio galaxies