Astronomers have discovered a galaxy dating back to an earlier epoch in the history of the Universe, which is surprisingly shaped like the Milky Way - a spiral structure with a straight band of stars and gas passing through its center - but much more massive, providing new insights into galaxy formation. This was reported by Reuters, writes UNN.
Details
This distant galaxy, named J0107a, was observed as it existed 11.1 billion years ago, when the Universe was about one-fifth of its current age. Researchers used data from the ALMA radio telescope in Chile and NASA's James Webb Space Telescope.
They determined that the mass of the galaxy, including stars and gas, exceeded the mass of the Milky Way by more than 10 times, and star formation occurred at a rate approximately 300 times higher than the modern rate. However, J0107a was more compact than the Milky Way.
"This is a monster among galaxies, with a high level of star formation and a large amount of gas - much more than in modern galaxies," said astronomer Shuo Huang of the National Astronomical Observatory of Japan.
"This discovery," added co-author Toshiki Saito of Shizuoka University in Japan, "raises an important question: how could such a massive galaxy form in such an early Universe?"
While some galaxies with similar star formation rates exist today, almost all of them are the result of merging or colliding galaxies. However, J0107a shows no signs of such processes.
J0107a and the Milky Way have common features.
They are equally huge and have a similar barred structure. But the Milky Way had enough time to form its structure, while J0107a did not
In the first billions of years after the Big Bang (13.8 billion years ago), galaxies were more turbulent and contained more gas, which contributed to extreme bursts of star formation. Organized structures, such as barred spirals, which are common now, were rare then.
Compared to other 'monsters' among galaxies in the early Universe, whose shapes are usually distorted or irregular, J0107a looks surprisingly similar to modern spiral galaxies
"This may require a revision of the theories of galactic structure formation," he added.
The James Webb Telescope, which looks at great distances into the past of the Universe, has already shown that spiral galaxies originated earlier than previously thought. J0107a is now one of the oldest known examples of a barred spiral galaxy.
The bar in J0107a is about 50,000 light-years long, Huang said. (One light-year is approximately 9.5 trillion km).
"The Webb Telescope is intensively studying the morphology of massive galaxies in the early Universe. But their dynamics are still poorly understood," Saito noted.