Hundreds of scientists worked together to map out one-quarter of the sky -- and they weren't just plotting landmarks of a road trip. They're creating a 3-D map of the universe!
Through painstaking, complex measurements that reached into the earliest chapters of the universe, they charted a 3-D model of 650 billion cubic light years of space that included 1.2 million galaxies.
It was created with an important goal -- to measure dark energy.
When scientists recently discovered that the expansion of the universe was accelerating, dark energy was suggested as the "anti-gravity" force responsible for it, perhaps even as the "cosmological constant" that Einstein envisioned.
The map is based on data collected over the course of a decade by scientists from several institutions affiliated with the Sloan Digital Sky Survey III's Baryon Oscillation Spectroscopic Survey (BOSS), a project that draws on the lasting impact of acoustic waves that undulated through the early universe.
The measurements for the map were made by determining the size of baryonic acoustic oscillations, or pressure waves that permeated that universe circa 400,000 years post-Big Bang. These waves left an imprint on the matter distribution of the universe and contributed to galaxies being separated by a characteristic distance, which scientists call the BAO scale. Using observations of the cosmic microwave background, scientists can detect what that primordial scale was, giving them a point of reference.
The scientists also had to account for the movements of the galaxies away from us in their measurements, and for the fact that the further away a galaxy is, the faster away from us it will move, which meant that scientists had to develop a model for galaxy distribution that took into account “the so-called redshift space distortion,” as Dr. Shun Saito from the Max Planck Institute for Astrophysics explained.
As scientists carefully took these variables into account and compared their data, they were not just measuring three-dimensional distances between objects we can see, but the amount of dark matter and dark energy that also fills the universe – two features that remain mysterious but appear to dictate much about how the universe is shaped and will continue to expand – as this research further confirms.
When the overall picture was constructed, they found their results to be consistent with standard cosmology, or the set of theories that essentially date our universe to 13 billion years ago when the Big Bang set matter into a rapid inflation, before cooling to temperatures able to sustain the formation of atoms.
The findings also indicate that if dark energy is the driving force of universal expansion, it is evolving very slowly.
"BOSS has marked an important cosmological milestone, combining precise clustering measurements of an enormous volume with extensive observations of the primary cosmic microwave background to produce a firm platform for the search for extensions to the standard cosmological model,” astronomer Jeremy Tinker of New York University told Phys.org.
Source: The Christian Science Monitor
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