Guess Where The Oldest Galaxies In The Universe Are

Federico Mansilla
Agosto 18, 2018

In the study, which was a joint venture between Durham University and the Harvard Smithsonian Center for Astrophysics, scientists identified two distinct populations of relic satellite galaxies tracking a course around the Milky Way. The first set is over 13 billion years old - among the oldest in the universe.

This is a key component of the widely accepted Lambda-cold-dark-matter model, and the team behind the latest research says its results support the model.

As Phys.org writes, hydrogen atoms congealed to make clouds, then become "halos" of dark matter. This period is sometimes called the Cosmic Dark Ages because there were no stars or other objects producing light or other frequencies in the electromagnetic spectrum.

Galaxies that named Segue-1, Bootes I, Tucana II and Ursa Major I are in fact some of the first galaxies ever formed. Hydrogen is the simplest of the known elements and continues to be the most prevalent element in the current-day universe. Eventually, they cooled enough to form stars and those stars became the first galaxies. It would take nearly 100 million years longer for the universe to cool enough that the atoms could clump together to form stars that populated the very first galaxies. One is very faint, composed of nebulae created during the cosmic dark ages. Consist of galaxies that formed hundreds of millions of years later.

Dr Alis Deason, a Royal Society University Research Fellow at the ICC, said: 'This is a wonderful example of how observations of the tiniest dwarf galaxies residing in our own Milky Way can be used to learn about the early universe'.

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Remarkably, the team found that a model of galaxy formation that they had developed previously agreed perfectly with the data, allowing them to infer the formation times of the satellite galaxies.

The intense ultraviolet radiation emitted by the first galaxies destroyed the remaining hydrogen atoms by ionizing them (knocking out their electrons), making it hard for this gas to cool and form new stars.

This distribution of older and younger galaxies are in line with the Lambda-cold-dark-matter model. Thus, galaxy formation resumed. The image has been generated from simulations from the Auriga project carried out by researchers at the Institute for Computational Cosmology, Durham University, UK, the Heidelberg Institute for Theoretical Studies, Germany, and the Max Planck Institute for Astrophysics, Germany.' Credit: Institute for Computational Cosmology, Durham University, UK/ Heidelberg Institute for Theoretical Studies, Germany / Max Planck Institute for Astrophysics, Germany.

'A decade ago, the faintest galaxies in the vicinity of the Milky Way would have gone under the radar.

"With the increasing sensitivity of present and future galaxy censuses", he continued, "a whole new trove of the tiniest galaxies has come into the light, allowing us to test theoretical models in new regimes".

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