Largest 3D map of the universe created detailing 1.2 million galaxies to measure dark energy

The largest ever 3D map of the universe has been developed thanks to the collaborative efforts of hundreds of scientists. The map which captures 1.2 million galaxies is aimed at aiding scientists to better understand and measure dark energy – a mysterious source of power which is believed to be the driving force behind the increasing rapid expansion of the universe.

Numerous teams of scientists from the Sloan Digital Sky Survey III (SDSS-III) project collaborated in efforts to make the map. "We have spent a decade collecting measurements of 1.2 million galaxies over one quarter of the sky to map out the structure of the Universe over a volume of 650 cubic billion light years," said Jeremy Tinker of New York University, a co-lead of the scientific team that led this effort.

"Using this map we will now be able to make the most accurate possible measurements of dark energy, and the part it plays in the expansion of the universe," said Dr Florian Beutler at the University of Portsmouth's Institute of Cosmology and Gravitation.

"We see a dramatic connection between the sound wave imprints seen in the cosmic microwave background 400,000 years after the Big Bang to the clustering of galaxies 7-12 billion years later," said Rita Tojeiro at the University of St Andrews.

How was the map created?

The project relied on the Baryon Oscillation Spectroscopic Survey (BOSS) program, which analysed "pressure waves" to measure the expansion rate of the universe. The BOSS program was original developed at a time when dark energy had already been attributed as the force behind the expansion of the universe. The program functioned by analysing the size of the baryonic acoustic oscillations (BAO), which are the periodic fluctuations that occur in matter that help cosmologists better comprehend the nature of dark energy. BOSS was specifically designed to measure the BAO feature through the evolution of the universe – seven billion years ago to near the present day.

What is dark energy?

According to Nasa, there are various theories about dark energy. One explains it as a still unexplored form of property in space, while another hypothesis refers to it as a kind of "dynamic energy field" that is ever present and fills all of space.

The new map also uncovers the characteristic signature of the movement of the galaxies, which shows how areas of the universe containing more matter are invariably drawing galaxies closer because of the attractive nature of the gravitational force.

A set of papers on the new map has been presented to the Monthly Notices of the Royal Astronomical Society.