Study Finds Evidence Dark Energy May Be Dynamic, Not Constant

This article was prepared from the source material provided, which includes a University of Portsmouth press release and a study published in Nature Astronomy.

Dark energy may not be the unchanging cosmological constant that Albert Einstein envisioned. A collaboration of astronomers, including researchers from the University of Portsmouth's Institute of Cosmology and Gravitation, has found evidence suggesting dark energy has a dynamic nature, according to a study published in the journal Nature Astronomy.

The finding rests on high-precision measurements of Baryonic Acoustic Oscillations — periodic fluctuations of matter composed of protons and neutrons — taken at multiple cosmic epochs in 2016. That data was collected by a team that included Gong-Bo Zhao of the ICG and the National Astronomical Observatories of China, who is the lead author of the new study. Combined with a new method Zhao developed, the astronomers reported evidence of dynamical dark energy at what the University of Portsmouth described as an undeniable degree of statistical certainty.

If confirmed, the result would mean dark energy is not a constant vacuum energy, represented by a constant Equation of State of -1, but some form of dynamical field. Dark energy is thought to be the mysterious force accelerating the expansion of the Universe and is estimated to make up 68 to 75 percent of the cosmos, while dark matter accounts for about 25 percent. Both are invisible, but their effects are observed through their interaction with gravity.

"Since its discovery at the end of last century, dark energy has been a riddle wrapped in an enigma," ICG director Bob Nichol said in a University of Portsmouth press release. "We are all desperate to gain some greater insight into its characteristics and origin. Such work helps us make progress in solving this 21st Century mystery."

Zhao said in the same release: "We are excited to see that current observations are able to probe the dynamics of dark energy at this level, and we hope that future observations will confirm what we see today."

The team is depending on future astronomical surveys to confirm the findings. One is the Dark Energy Spectroscopic Instrument survey, slated to begin work on a 3D cosmic map in 2018. The long-awaited James Webb Space Telescope could also help make observations that shed light on dark energy's mysteries.