Portrait of the young galaxy throws the theory of galaxy formation on its head

Scientists have challenged our current understanding of how galaxies formed by revealing photos of a young galaxy in the early life of the universe that look surprisingly mature.

The galaxy, called ALESS 073.1, apparently has all the features expected of a much more mature galaxy and has led the team of scientists to question how fast it has grown.

The new research is in today Science.

Galaxies come in different shapes, sizes and colors, and consist of different components, such as rotating disks, spiral arms and “bumps”.

A major goal of contemporary astronomy is to understand why different galaxies look like today and when their different components are formed.

The team, led by scientists from Cardiff University, used the Atacama Large Millimeter / submillimeter Array (ALMA) telescope as a ‘time machine’ to look at the distant past, revealing how ALESS 073.1 only 1.2 billion years after the big bang.

Because the light emitted from the galaxy took billions of years to reach our telescopes on Earth, the team was able to investigate what the galaxy looked like during its infancy and determine how it was initially formed.

The result was one of the sharpest, direct images of an original galaxy ever produced, enabling the team to conduct a detailed study of its internal structure.

“We discovered that a massive hump, a regular rotating disk and possibly spiral arms were already in place in this galaxy when the universe was only 10% of its current age,” says lead author of the study, Dr. Federico Lelli, who undertook the work at Cardiff University’s School of Physics and Astronomy.

“In other words, this galaxy looks like a full-grown adult, but it should only be a small child.”

Co-author of the study Dr. Timothy Davis, of the School of Physics and Astronomy, said: “This spectacular discovery challenges our current understanding of how galaxies form because we believed that these traits originated only in” adult “galaxies, not in young people. . “

One important feature of a galaxy is the presence of a so-called bulge – a solid group of stars that is usually located in the center of the galaxy.

It was believed that massive bulges were slowly formed by the fusion of smaller galaxies or by specific processes that took place within the galaxy itself; however, the kinematic properties of ALESS 073.1 have revealed that the formation of massive bulges can occur extremely rapidly – it has been shown that about half of the stars in the galaxy are in a mound.

Similarly, it is known that some adult galaxies, such as our own Milky Way, have spiral arms extending from their central parts, giving them a distinctive spiral shape.

Similar features were also unexpectedly spotted in ALESS 073.1, much to the surprise of the team, as early galaxies are usually chaotic and turbulent rather than having regular, well-organized structures such as spiral arms.

“A galaxy like ALESS 073.1 only resists our understanding of the formation of galaxies,” concluded Dr. Lelli.