Spectacular insights into the early life of galaxies | Science| In-depth reporting on science and technology | DW | 22.05.2015
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Science

Spectacular insights into the early life of galaxies

Astronomers at the Very Large Telescope have taken the best 3D-pictures of the early universe ever. They discovered objects emitting so little light that the Hubble Telescope could not find them.

MUSE übertrifft Hubble beim Hubble Deep Field South

In the small boxes one can see the objects, newly discovered with the MUSE Instrument.

Astronomers, who want to look deep into the universe and back in time must focus their telescopes on the same place in the sky for as long as possible. This is how researchers take so-called deep-field pictures.

Babyfoto des Universums Planck-Satellit

The Young universe: Microwave Radiation - seen here in a visualisation - emerged 380.000 years after the Big Bang.

The most wellknown of them come from the Hubble Space Telecope. In 1995 astronomers first focused on a region of the skies in the Northern Hemisphere to research galaxies that are extremely far away and in early stages of their development.

Three years later, the astronomers selected a region of the skies in the Southern Hemisphere where they repeated the observation procedure for ten days.

The resulting pictures are considered a milestone in cosmology. Researchers found a lot of valuable information in them, helping them to check previous theories and models like the question whether the universe really looks the same everywhere. And indeed: The pictures showed many galaxies of similar shapes and colors.

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The universe as wee see it

Theoretically, everything that we see today developed out of a hot, homogenous gas. That includes stars and galaxies like our Milky Way. Soon after the Big Bang, dark matter triggered the compression of that gas into matter as we know it today. Wherever that mysterious dark matter was, the matter we find today was concentrating.

Over billions of years the structures got bigger and bigger. The first stars and galaxies and eventually also the large spiral galaxies like the Milky Way emerged. How these structures developed and will develop in the future is a central question of astronomy. To answer that question, astronomers need the most detailed pictures possible of galaxies in different stages of their development.

Celestial Secrets

So far research has shown that the Milky Way has grown by cannibalizing other galaxies - grabbing stars, pulling them away and even swallowing some. Astronomers have seen many such incidents where galaxies get intermingled and eventually merge.

Even our Milky Way and the neighboring Andromeda galaxy are on a collision course. Both are racing toward at each other with a speed of 400.000 kilometers per hour. Their gravity will eventually bind them together and make one huge elliptic galaxy out of them.

The early stages in the development of galaxies is largely unknown. Very young galaxies are so far away from us that even deep-field pictures taken by the Hubble Space Telescope are unable to deliver that information.

Andromeda Galaxie,

This is, how the Crash between Milky Way and the Andromeda Galaxy could look like in four Million years.

A new window into the universe

Last year scientists started using the new Very Large Telescope (VLT) in Chile, including the Multi Unit Spectroscopic Explorer MUSE. It combines observations of the skies with spectroscopy. For each pixel in a picture it provides a spectrum, disclosing the intensity of different colors of light at that point. This enables the scientists to study different views of a given object at different wavelengths.

Now the astronomers used MUSE to observe the same area in the southern skies that Hubble observed in 1998. Hubble had ten days for its observation, Muse only took 27 hours. Nonetheless, Muse discovered more than 20 new objects, which Hubble was unable to see. The researchers are thrilled.

"After only a few hours we looked at the data and already identified several new galaxies," project head Roland Bacon from the French Centre de Recherche Astrophysique de Lyon said. "This was very encouraging. It is like finding fish in the deep sea: Every new catch triggers lots of excitement about what kind of species we may have found."

The three-dimensional picture of the early universe shows: With MUSE, astronomers can research the makeup and distance of far away galaxies and even movements within these galaxies very precisely. This will help scientists to understand what was happening when these galaxies were born.

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