Some of the universe's earliest galaxies circle the Milky Way

Astronomers identify some of the oldest galaxies in the universe

Astronomers identify some of the oldest galaxies in the universe

The discovery sheds fresh light on the evolution of the universe, according to researchers from the Institute for Computational Cosmology at Durham University and the Harvard-Smithsonian Centre for Astrophysics.

Based on that knowledge, the team identified two populations of satellite galaxies circling the Milky Way. The first set is over 13 billion years old - among the oldest in the universe.

The image below shows the distribution of satellite galaxies orbiting a computer-simulated galaxy, as predicted by the Lambda-cold-dark-matter cosmological model.

Galaxy creation stalled for roughly a billion years as the ionized hydrogen atoms cooled back down to the point where they could settle into larger dark matter haloes, and be used up in the creation of further stars and galaxies. Consist of galaxies that formed during "cosmic dark ages". and 2. In the "old" set are Segue-1, Bootes I, Tucana II, and Ursa Major I. The team found a similar distribution among observable dwarf galaxies in orbit of M31 (Andromeda).

These were tiny particles of hydrogen which are the simplest element in the periodic table. 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. Eventually, they cooled enough to form stars and those stars became the first galaxies. One is very faint, composed of nebulae created during the cosmic dark ages. The other is slightly brighter, made of galaxies formed hundreds of millions of years later.

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. But then, galaxy formation stopped for about a billion years.

The intense ultraviolet radiation from those early galaxies ionized the remaining hydrogen atoms, making it harder for them to cool and form stars.

Galaxy formation resumed - culminating in the formation of spectacular bright galaxies like our own Milky Way.

Researchers hope the star, known as J0815+4729, which is in line with the Lynx constellation, will help them learn more about the Big Bang, the popular theory about the galaxy's evolution. 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. Ten years ago, the faintest of the galaxies near the Milky Way would have gone undetected.

"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".