China News Agency, Beijing, May 21 (Reporter Sun Zifa) The international academic journal Nature recently published an astronomy research paper describing a massive rotating galaxy disk formed 1.5 billion years after the Big Bang, because of its distance Longer than the time predicted by traditional galaxy formation models, it will exacerbate a long-standing debate about when and how disk galaxies (such as the Milky Way) formed.
The Wolfe disk galaxy under the ALMA telescope (red on the right), VLA (green on the left) and the Hubble telescope (blue in the two images). (Copyright ALMA (ESO NAOJ NRAO), M. Neeleman; NRAO AUI NSF, S. Dagnello; NASA ESA Hubble) Photo courtesy of natural science research
Astronomers said that according to current cosmological understanding, galaxies are considered to be formed by layered mergers. The dark matter "halo" is formed first, attracting the surrounding gas and fusing into a larger structure, forming stars from it, and then contributing to the birth of the galaxy. The traditional view of galaxy formation believes that the falling gas is heated and the resulting spherical structure cools down in the central area, which can only support the formation of a disk.
The radiograph of Wolfe Disk under the ALMA telescope, at this time the age of the universe is only one-tenth of what it is today. (Copyright ALMA (ESO NAOJ NRAO), M. Neeleman; NRAO AUI NSF, S. Dagnello) Image courtesy of scientific research
In the latest paper, Marcel Neeleman of the Max Planck Institute for Astronomy in Germany and colleagues report that an early disk galaxy supports another hypothesis, the so-called cold accretion model. They proved that in a galaxy formed about 12.5 billion years ago, there was a cooler dusty rotating disk. This suggests that the falling gas may be cold, allowing disk galaxies to condense quickly. It is estimated that the mass of the galaxy is 72 billion times that of the sun, and the rotation speed of the disk galaxy is about 272 km / s.
Artistic rendering of the Wolfe disk galaxy. (Copyright NRAO AUI NSF, S. Dagnello) Photo courtesy of natural science research
Marcel Neilman and J. Xavier Prochaska (University of California, Santa Cruz) are co-corresponding authors of the paper. Alfred Tiley of the University of Western Australia in Australia published a "News and Opinions" article on the results of the paper, pointing out that this study shows that the formation time of a large gas disk may be earlier than other recent observations. 100 million years, but he emphasized that this research is only based on a galaxy. In the future, similar observations on more galaxies are needed to determine whether the cold accretion model is a common way of forming galaxies. (Finish)