Nav: Home

Holes in the Universe sharpen cosmic measurements

July 10, 2019

Regions of the Universe containing very few or no galaxies - known as voids - can help measure cosmic expansion with much greater precision than before, according to new research.

The study looked at the shapes of voids found in data from the Sloan Digital Sky Survey (SDSS) collaboration. Voids come in a variety shapes, but because they have no preferred direction of alignment, a large enough sample of them can on average be used as "standard spheres" - objects which should appear perfectly symmetric in the absence of any distortions.

However, the observed shapes of these spheres are distorted by Doppler shifts in the redshifts of nearby galaxies caused by the local velocity field, and by the nature and amounts of dark matter and dark energy that make up 95% of the Universe. This distortion can be theoretically modelled, and the new work shows it can now be precisely measured.

The research was led by the University of Portsmouth, a world leader in cosmology, and is published this week in Physical Review D.

The new measurement of the distortion around voids used the Baryon Oscillation Spectroscopic Survey (BOSS) of galaxies from SDSS, that was designed to measure dark energy and the curvature of space.

For measuring a key aspect of the cosmic expansion, the new method greatly outperforms the standard baryon acoustic oscillation (BAO) technique that BOSS was designed for. The new results agree with the simplest model of a flat Universe with a cosmological constant dark energy, and tighten the constraints on alternative theories.

Lead author, Dr Seshadri Nadathur, research fellow at the University's Institute of Cosmology and Gravitation (ICG), said: "This measurement tremendously upgrades the previous best results from BOSS - the precision is equivalent to getting data from a hypothetical survey four times as large as BOSS, completely for free. It really helps pin down the properties of dark energy."

"These results also mean that the expected science results from facilities such as the European Space Agency's Euclid satellite mission and the Dark Energy Spectroscopic Instrument - in which the astronomy community have invested a lot of resources - can be even better than previously thought."
-end-
The other authors include Portsmouth's PhD student Paul Carter, research fellows Dr Hans Winther and Dr Julian Bautista, and former Portsmouth Professor Will Percival, who has recently taken up a new role in Canada.

CAPTION: The change in the average shape of voids caused by Doppler distortions and the effects of dark energy and curvature.

University of Portsmouth

Related Dark Energy Articles:

Origin of Milky Way's hypothetical dark matter signal may not be so dark
A mysterious gamma-ray glow at the center of the Milky Way is most likely caused by pulsars.
Explaining the accelerating expansion of the universe without dark energy
Enigmatic dark energy, thought to make up 68 percent of the universe, may not exist at all, according to a Hungarian-American team.
Wave energy researchers dive deep to advance clean energy source
One of the biggest untapped clean energy sources on the planet -- wave energy -- could one day power millions of homes across the US.
Dark energy measured with record-breaking map of 1.2 million galaxies
A team of hundreds of physicists and astronomers, including those from Berkeley Lab, have announced results from the largest-ever, three-dimensional map of distant galaxies.
Astronomers map a record-breaking 1.2 million galaxies to study the secrets of dark energy
Astronomers announced this week the sharpest results yet on the properties of dark energy.
Accelerating research into dark energy
A quick method for making accurate, virtual universes to help understand the effects of dark matter and dark energy has been developed by UCL and CEFCA scientists.
MIT Energy Initiative welcomes Exelon as member for clean energy research
MIT Energy Initiative announces that national energy provider Exelon joins MITEI as a member to focus research support through MITEI's Low-Carbon Energy Centers.
ASU professor honored for work on energy and social aspects of energy policy
Martin 'Mike' Pasqualetti, an Arizona State University professor and an expert on energy and social components of energy development, will be awarded 2015 Alexander and Ilse Melamid Memorial Medal by the American Geographical Society.
DESI, an ambitious probe of dark energy, achieves its next major milestone
The US Department of Energy has announced approval of Critical Decision 2 (CD-2), authorizing the scientific scope, schedule, and funding profile of DESI, the Dark Energy Spectroscopic Instrument, an exceptional apparatus designed to improve our understanding of the role of dark energy in the expansion history of the universe.
Searching for ingredients of dark matter and dark energy
Two new reports advance efforts to identify components of dark matter and energy, which together comprise about 95 percent of the universe yet leave much to scientists' imaginations.

Related Dark Energy Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...