Black holes as a source of dark energy: Sky atlas provides new evidence
A year ago, a radical hypothesis on the origin of dark energy caused a stir. Now the proponents are presenting new evidence for it.
Image of galaxies in the early universe: At that time, the rate of star formation was at its highest and a particularly large number of black holes were also formed at this time.
(Image: NASA, ESA, CSA, Maria Polletta (INAF), Hervé Dole (Paris), Brenda Frye (UofA), Jordan C. J. D'Silva (UWA), Anton M. Koekemoer (STScI), Jake Summers (ASU), Rogier Windhorst (ASU))
A research group from the USA has found "tantalizing evidence" that black holes actually convert matter into dark energy. The team led by astronomer Kevin Croker from Arizona State University writes this and refers to measurement data from the Dark Energy Spectroscopic Instrument (DESI). These would have shown that the rate of formation of black holes would match the increase in dark energy in the universe. "This makes it more plausible that black holes are the source of dark energy," adds co-author Duncan Farrah. Although it is not known exactly how this happens –, the discovery is proof that it does happen, Croker claims.
With the theory that black holes are behind the mysterious dark energy, several of the authors involved in the recently published study attracted attention a year and a half ago. At first glance, the theory seemed sound, but on closer inspection it became entangled in contradictions and was not really convincingly substantiated. Nevertheless, even critics recognized that the hypothesis could not simply be dismissed and called for further research. This is exactly what Croker's team has now done with the Dark Energy Spectroscopic Instrument. Its measurement data would provide further evidence that the postulated correlation actually exists.
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Based on measurements of tens of millions of distant galaxies, the team analyzed how many black holes were created at different stages of the universe's development. Together with the indications, also from DESI, that the density of dark energy has changed over time, this provides evidence that the two phenomena fit together. While a possible connection between the growth of black holes and dark energy had previously been analyzed, the new work links the mysterious form of energy with its formation from dying stars. The work was published in the Journal of Cosmology and Astroparticle Physics. According to the team, it shows that the question is no longer purely theoretical, but can now also be approached experimentally.
Fascinating measurement data
The DESI has been collecting spectra of tens of millions of galaxies since 2021, covering around a third of the night sky. From the spectra, researchers can not only deduce the chemical composition of the emitting objects, but also their relative distance and proper motion – depending on how far they are shifted into the red. The aim is to create the most comprehensive map of the expanding universe. Thanks to robot-controlled glass fibers, the instrument can simultaneously capture the spectra of 5,000 galaxies and measure up to 150,000 objects on a good night. So far, the first exciting theories are based solely on the data collected in the first year after commissioning.
(mho)
