Researchers create the largest ever three-dimensional map of the distant universe

Scientists have created the largest ever three-dimensional map of the distant universe in light of the brightest objects in the cosmos. The researchers used the light of 14,000 quasars, supermassive black holes at the center of galaxies billions of light years, with the third Sloan Digital Sky Survey (SDSS-III) to construct the 3-D map.

The map is a first important result baryon Oscillation Spectroscopic Survey (head), SDSS-III, the largest study, which is the principal investigator, David Schlegel, and the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab). A great new map was presented at the April meeting of the American Physical Society in Anaheim, California, which is Anze Slosar at Brookhaven National Laboratory.

"Quasars are the brightest objects in the universe, which we use as convenient backlights to illuminate the intervening hydrogen gas that fills the universe between us and them," Slosar said.

"We can see their shadows, and the details in their shadows, specifically, the absorption features in their spectra known as the Lyman-alpha forest, allowing us to see how the gas is clumped along our line of sight.

"The amazing thing is that this allows us to see the universe so very far away, where measuring positions of individual galaxies in large numbers is impractical," Slosar stated.

BOSS is the first attempt to use the baryon acoustic oscillation (BAO) as a precision tool for measuring dark energy. Baryon oscillation refers to how groups regularly throughout the universe, a physical manifestation of the expanding universe. So far, the 3-D maps showing the swing is based on the distribution of visible galaxies. BOSS is the first survey of intergalactic hydrogen map, with distant quasars whose light is produced by a supermassive black hole at the center of active galaxies.

"BOSS is the first attempt to use the Lyman-alpha forest to measure dark energy," principal investigator Schlegel said.

"Because the Sloan Telescope has such a wide field of view, and because these quasars are so faint, there was no one who wasn't nervous about whether we could really bring it off," he stated.

Using the 14 000 quasars and compiled by the Sloan telescope at Apache Point Observatory in New Mexico during the first year the Boss relevant period of five years, if a new map that is really possible to establish changes in the density of intergalactic hydrogen gas at distances of cosmology and dark energy to measure the impact of those trips. Slosar, leading to the Lyman-alpha cosmology boss of the group, says that although similar measures have been made to individual galaxies or young galaxies in the past

"These have given only one-dimensional information about fluctuations in density along the line of sight. Before now there has never been enough density of quasars for a 3-D view," Slosar said.

The wide-field Sloan Telescope covers a wide expanse of sky at moderate magnification. To measure both galaxies and quasars, a thousand targets for each BOSS exposure are selected in advance from existing surveys.

At the telescope's focal plane, "plug plates" are precision-machine-drilled with tiny holes at positions of known galaxies and quasars.

These holes are plugged with optical fibres that channel the light from each chosen galaxy or quasar to a spectrograph, which isolates the spectrum of each individual object.

Schlegel credits Berkeley Lab's Nicholas Ross for doing much of the "incredibly hard work" involved in this targeting.

"Our exploratory paper includes less than a tenth of the 160,000 quasars that BOSS will study, but already that's enough to establish a proof of the concept," Slosar said.

"This is a potentially revolutionary technique for mapping the very distant universe. We're paving the way for future BAO experiments like BigBOSS to follow suit," Slosar stated.

BigBOSS is a proposed survey that will find precise locations for 20 million galaxies and quasars and go beyond BOSS to encompass 10 times the volume of the finished BOSS map.

"By the time BOSS ends, we will be able to measure how fast the universe was expanding 11 billion years ago with an accuracy of a couple of percent," Patrick McDonald of Berkeley Lab and Brookhaven, who pioneered techniques for measuring the universe with the Lyman-alpha forest, said.

"Considering that no one has ever measured the cosmic expansion rate so far back in time, that's a pretty astonishing prospect," he stated.