Viewing the Adolescent Universe in 3-D

Using a novel technique to create a high-resolution map, scientists can now view the adolescent Universe in 3-D, new research describes.

Based on extremely faint light from galaxies located 10.8 billion light-years away, the map shows a web of hydrogen gas that varies from low to high density at a time when the Universe was made of a fraction of the dark matter we see today. It's these distant galaxies that backlight hydrogen gas to provide a clearer picture of a younger Universe.

Scientists hope that this new technique can guide future mapping projects, like the Dark Energy Spectroscopic Instrument (DESI), scheduled to start in 2018.

"DESI was designed without the possibility of extracting such information from the most distant, faint galaxies," researcher David Schlegel said in a statement. "Now that we know this is possible, DESI promises to be even more powerful."

The first big 3-D map of the Universe was created using data from the Sloan Digital Sky Survey (SDSS), which began in 1998. As technology has advanced over the years, scientists have now stretched our ability to map the Universe to about six billion light-years. However, Schlegel notes that the map is still incomplete in some areas.

Previous mapping techniques relied on what is called Lyman-alpha tomography, comparable to computer tomography (CT) scans used in the medicine field. As light from distant background galaxies travel through the Universe towards Earth, the absorption signatures from hydrogen gas are imprinted, creating a 3-D map of the cosmic web. But, if researchers were to apply this technique to galaxies known as quasars, which are few and far between, it would create data holes in the map.

So this newly developed technique, which uses the faint light of numerous distant galaxies instead of that of sparse quasars, promises to fill in these gaps.

This innovation will allow scientists operating DESI to extend current maps to about 10 billion light-years away.

The findings are to be published in an upcoming issue of Astrophysical Journal Letters.