Astronomers have known for a while that the expansion of the Universe is speeding up, but the physics of this expansion is still a mystery. Now, a team of scientists at the University of Hawai’i at Mānoa has come up with a new prediction – the dark energy liable for this accelerating growth comes from an extended sea of compact objects spread throughout the voids between galaxies.
The conclusion is detailed in a new study that has been published in The Astrophysical Journal.
Mimicking Black Holes
In the mid-1960s, researchers first proposed that stellar collapse should not make true black holes, but should rather form Generic Objects of Dark Energy (GEODEs). Dissimilar to black holes, GEODEs do not breach Einstein‘s equations with singularities.
Rather, a spinning layer surrounds a nucleus of dark energy. Regarded from the outside, GEODEs and black holes seem to be mostly the same, even with the ‘sounds’ of their crashes are calculated by gravitational wave observatories. Because GEODEs are similar to black holes, it was presumed they moved through space in the same manner as black holes.
“This becomes a problem if you want to explain the accelerating expansion of the universe,” said UH Mānoa Department of Physics and Astronomy research fellow Kevin Croker, lead author of the study. “Even though we proved last year that GEODEs, in principle, could provide the necessary dark energy, you need lots of old and massive GEODEs. If they moved like black holes, staying close to visible matter, galaxies like our own Milky Way would have been disrupted.”
Mutually Repulsing Each Other
Croker partnered with UH Mānoa Department of Physics and Astronomy graduate student Jack Runburg, as well as Duncan Farrah, a faculty member at the UH Institute for Astronomy and the Physics and Astronomy department, to examine the way GEODEs move through space.
The scientists found that the spinning sheet around each GEODE decides the way they move relative to each other. If their outer layer twists slowly, GEODEs gather more rapidly than black holes. This is due to the fact that GEODEs accumulate mass from the expansion of the Universe itself. For GEODEs with layers that twist close to the speed of light, though, the mass accumulation becomes led by a different impact, and the GEODEs start to reject each other.
“The dependence on spin was really quite unexpected,” said Farrah. “If confirmed by observation, it would be an entirely new class of phenomenon.”
The team managed to solve Einstein’s equations by presuming that many of the ancient stars, which took shape when the Universe was less than two percent of its current age, formed GEODEs when they died.
As these old GEODEs pulled in other stars and lots of interstellar gas, they start to spin at high velocities. Once spinning sufficiently quick, the GEODEs’ mutual repulsion made most of them distance into zones that would ultimately become the empty voids between today’s galaxies.
GEODEs are the Key to Solving the Dark Energy Problem
This research supports the theory that GEODEs can address the dark energy mystery while remaining in accord with various observations across extended distances. GEODEs stay away from today’s galaxies, so they do not interrupt frail pairs of stars located within the Milky Way. The number of ancient GEODEs needed to solve the dark energy enigma is even with the number of old stars.
GEODEs do not mess with the calculated distribution of galaxies in space due to the fact that they divide away from luminous matter before it creates present-day galaxies. Finally, GEODEs do not directly impact the delicate ripples in the afterglow of Big Bang because they are born from dead stars hundred of millions of years after the discharge of this cosmic background radiation.
“It was thought that, without a direct detection of something different than a Kerr [Black Hole] signature from LIGO-Virgo [gravitational wave observatories], you’d never be able to tell that GEODEs existed,” said Farrah. Croker added, “but now that we have a clearer understanding of how Einstein’s equations link big and small, we’ve been able to make contact with data from many communities, and a coherent picture is beginning to form.”