Holes in the universe accentuate cosmic measurements

According to new research, regions of the universe containing very few or no galaxies, called voids, can help measure cosmic expansion with much greater accuracy than previously.

The study examined the shape of the gaps found in the data of the SDSS (Sloan Digital Sky Survey) collaboration. The voids come in various forms, but as they have no privileged direction of alignment, we can on average use a fairly large sample as "standard spheres", objects that should appear perfectly symmetrical in the no distortion.

However, the observed shapes of these spheres are distorted by Doppler shifts in the red shifts of nearby galaxies caused by the local velocity field, as well as by the nature and amounts of dark matter and dark energy that constitute 95% of the Universe. This distortion can be theoretically modeled and the new work shows that it can now be accurately measured.

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

The new measure of void-based distortion used the Baryon Oscillation Spectroscopic Survey (BOSS) of SDSS galaxies, designed to measure dark energy and curvature of space.

To measure a key aspect of cosmic expansion, the new method far surpasses the standard baryonic acoustic oscillation (BAO) technique for which BOSS was designed. The new findings are consistent with the simplest model of a flat universe with a dark cosmological constant energy and tighten the constraints on alternative theories.

Seshadri Nadathur, a researcher at the University's Institute of Cosmology and Gravitation (ICG), said: "This measure significantly improves BOSS's previous best results – accuracy equates to getting data from a hypothetical four-point survey. times. " As big as BOSS, absolutely free. This really helps to identify the properties of dark energy. "

"These results also mean that expected scientific results from facilities such as the Euclid satellite mission from the European Space Agency and the dark energy spectroscopic instrument – in which the astronomical community has invested a lot of resources – may be even better than previously thought. "

Other writers include Ph.D. from Portsmouth. Paul Carter, student, researchers Hans Winther and Julian Bautista, and former Portsmouth professor, Will Percival, who recently assumed a new role in Canada.