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."
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:

Are black holes made of dark energy?
Two University of Hawaii at Manoa researchers have identified and corrected a subtle error that was made when applying Einstein's equations to model the growth of the universe.
Lab-based dark energy experiment narrows search options for elusive force
An experiment to test a popular theory of dark energy has found no evidence of new forces, placing strong constraints on related theories.
A survey machine and a data trove: Dark Energy Survey's rich legacy
On the night of Jan. 9, 2019, the V. M.
String theory: Is dark energy even allowed?
In string theory, a paradigm shift could be imminent. In June, a team of string theorists from Harvard and Caltech published a conjecture which sounded revolutionary: String theory is said to be fundamentally incompatible with our current understanding of 'dark energy'.
The dark secrets of social media dark patterns
MSU researchers used the GamerGate controversy to uncover how one angry social media user inspired thousands to join its movement, amplify its messages, cyberbully innocent users and ultimately get thousands more to participate ... without the users even knowing it.
Dark energy survey publicly releases first three years of data
At a special session held during the American Astronomical Society meeting in Washington, D.C., scientists on the Dark Energy Survey (DES) announced today the public release of their first three years of data.
Star mergers: A new test of gravity, dark energy theories
Observations and measurements of a neutron star merger have largely ruled out some theories relating to gravity and dark energy, and challenged a large class of theories.
Doing without dark energy
Three mathematicians have a different explanation for the accelerating expansion of the universe that does without theories of 'dark energy.' Einstein's original equations for General Relativity actually predict cosmic acceleration due to an 'instability,' they argue in paper published recently in Proceedings of the Royal Society A.
How blood-sucking insects find dark-coated cattle in the dark
Last year, biologist Susanne Åkesson at Lund University in Sweden, together with researchers in Hungary, received the Ig Nobel Prize in Physics.
Dark matter and dark energy: Do they really exist?
Researchers have hypothesized that the universe contains a 'dark matter.' They have also posited the existence of a 'dark energy.' These two hypotheses account for the movement of stars in galaxies and for the accelerating expansion of the universe.
More Dark Energy News and Dark Energy Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab