New test of dark energy and expansion from cosmic structures

Date:
June 3, 2020
Source:
University of Portsmouth
Summary:
A new paper has shown how large structures in the distribution of
galaxies in the Universe provide the most precise tests of dark
energy and cosmic expansion yet.



FULL STORY ========================================================================== [Starry night sky (stock | Credit: (c) clearviewstock / stock.adobe.com]
Starry night sky (stock image).

Credit: (c) clearviewstock / stock.adobe.com [Starry night sky (stock |
Credit: (c) clearviewstock / stock.adobe.com] Starry night sky (stock
image).

Credit: (c) clearviewstock / stock.adobe.com Close A new paper has shown
how large structures in the distribution of galaxies in the Universe
provide the most precise tests of dark energy and cosmic expansion yet.


==========================================================================
The study uses a new method based on a combination of cosmic voids --
large expanding bubbles of space containing very few galaxies -- and
the faint imprint of sound waves in the very early Universe, known as
baryon acoustic oscillations (BAO), that can be seen in the distribution
of galaxies. This provides a precise ruler to measure the direct effects
of dark energy driving the accelerated expansion of the Universe.

This new method gives much more precise results than the technique
based on the observation of exploding massive stars, or supernovae,
which has long been the standard method for measuring the direct effects
of dark energy.

The research was led by the University of Portsmouth, and is published
in Physical Review Letters.

The study makes use of data from over a million galaxies and quasars
gathered over more than a decade of operations by the Sloan Digital
Sky Survey.

The results confirm the model of a cosmological constant dark energy
and spatially flat Universe to unprecedented accuracy, and strongly
disfavour recent suggestions of positive spatial curvature inferred
from measurements of the cosmic microwave background (CMB) by the Planck satellite.

Lead author Dr Seshadri Nadathur, research fellow at the University's
Institute of Cosmology and Gravitation (ICG), said: "This result shows
the power of galaxy surveys to pin down the amount of dark energy and
how it evolved over the last billion years. We're making really precise measurements now and the data is going to get even better with new surveys coming online very soon." Dr Florian Beutler, a senior research fellow
at the ICG, who was also involved in the work, said that the study also reported a new precise measurement of the Hubble constant, the value of
which has recently been the subject of intense debate among astronomers.

He said: "We see tentative evidence that data from relatively nearby voids
and BAO favour the high Hubble rate seen from other low-redshift methods,
but including data from more distant quasar absorption lines brings it
in better agreement with the value inferred from Planck CMB data."

========================================================================== Story Source: Materials provided by University_of_Portsmouth. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Seshadri Nadathur, Will J. Percival, Florian Beutler, Hans
A. Winther.

Testing Low-Redshift Cosmic Acceleration with Large-Scale Structure.

Physical Review Letters, 2020; 124 (22) DOI: 10.1103/
PhysRevLett.124.221301 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200603120551.htm https://www.sciencedaily.com/releases/2020/06/200603120551.htm

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