Astronomers discover 72 ancient galaxies in Hubble Ultra Deep Field

Spectroscopic instrument allowed scientists deepest ever view into the early universe.
By Laurel Kornfeld | Dec 01, 2017
A team of astronomers using the Multi Unit Spectroscopic Explorer (MUSE), an instrument attached to the Very Large Telescope in Chile, discovered 72 ancient galaxies in the region of the sky known as the Hubble Ultra Deep Field (HUDF).

The region was famously photographed in the highest-ever resolution to date by the Hubble Space Telescope in 2004 and revealed almost 10,000 galaxies in a part of the sky thought to be empty.

Many of those galaxies are 13 billion light years away, meaning they date back to just one billion years after the Big Bang.

Now, scientists observing that same region with MUSE, a spectroscopic instrument capable of detecting galaxies 100 times fainter than any previous study, found 72 more galaxies dating back to the universe's earliest years.

Just one-tenth the size of the full Moon, the Hubble Ultra Deep Field is located in the direction of the constellation Fornax.

"MUSE can do something that Hubble can't," explained Roland Bacon of the Lyon Astrophysical Research Center in France and principal investigator of the project.

"It splits up the light from every point in the image into its component colors to create a spectrum. This allows us to measure the distance, colors, and other properties of all the galaxies we can see--including some that are invisible to Hubble itself."

As a spectroscopic instrument, MUSE measures light emitted, absorbed, or scattered in space, allowing scientists to pin down the rate at which stars and galaxies are moving as along with their composition.

The instrument's adaptive optics were recently upgraded, enhancing its abilities to look back into the ancient universe.

Unexpectedly, these 72 galaxies shine only in Lyman-alpha light, a type of ultraviolet light associated with the most distant objects.

"MUSE has the unique ability to extract information about some of the earliest galaxies in the universe--even in a part of the sky that is already very well-studied," said team member Jarle Brinchmann of Leiden University in the Netherlands and of the Institute of Astrophysics and Space Sciences at CAUP in Portugal.

Brinchmann is lead author of one of ten articles on the finding published in a special issue of the journal Astronomy and Astrophysics.

Spectroscopy enables scientists to learn about the internal motion and chemical content of many galaxies at once, he emphasized.

Through MUSE, scientists also discovered hydrogen halos in old galaxies. Further study of these halos will help them better understand the process by which materials entered and left galaxies in the early universe.

Additionally, the team of over 50 astronomers successfully measured the distances and characteristics of 1,600 extremely faint galaxies in the region.



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