Astronomers have discovered a cosmic "dragon" — the most distant and massive spiral galaxy known to date.

Recently, Naked Science reported on the observation of A2744-GDSp-z4 — an unusual spiral galaxy with two arms. This relatively small and massive object formed just one and a half billion years after the Big Bang and astonished astronomers: it was believed that such structures hardly ever formed in the early Universe.

Now, an international research team led by Mengyuan Xiao from the University of Geneva (Switzerland) has announced the discovery of another ancient inhabitant of space — the giant spiral galaxy Zhulong.

In a study presented on the Cornell University preprint server, it is stated that the distinctly defined arms of the cosmic "dragon" stretch from the bulge (a spheroidal concentration of stars at the center of the galaxy) almost to the edges of the disk, extending over 62 thousand light-years (a scale comparable to that of the Milky Way's disk).

It was traditionally believed that such massive and "organized" spiral galaxies appeared a couple to a few billion years after the birth of the Universe; however, the discoveries of A2744-GDSp-z4 and Zhulong demonstrate that the evolution of certain galaxies (the rare and "fortunate" ones) may have occurred at an accelerated pace. Both discoveries resulted from imaging distant regions of the sky in the near-infrared range using the James Webb Space Telescope.

A surprise for astronomers was the mass of Zhulong, comparable to that of our Galaxy. However, the Milky Way took on its shape over 13 billion years of evolution, while the cosmic "dragon" "matured" in just one billion years. Moreover, stars within it formed much faster than in star-forming galaxies of later epochs.

By analyzing the energy distribution of stars across wavelengths in the images (using photometric analysis), the researchers concluded that the bulge at the center of Zhulong represents a "core" with minimal star formation, while its main population predominantly consists of aging stars. At the same time, new stars continued to be born in the outer regions of the cosmic "dragon," forming a characteristic disk.

This finding prompts a reevaluation of our understanding of the speed and efficiency of forming large structures in the early Universe. Further observations and detailed spectral analysis will help answer questions about how exactly this remarkable galaxy acquired its spiral "framework" and "classic" bulge. Specifically, the distribution of gas and stars, as well as the rotation speed of Zhulong, can be determined using the ALMA radio telescope.

Modern models of galaxy formation are hierarchical, suggesting that galaxies with the simplest structures appear first, and only after a lengthy evolution, often involving collisions and mergers with other galaxies, can spiral structures like the Milky Way emerge. However, new observations of the "dragon" clearly demonstrate that galaxy formation occurs differently, and the early Universe evolved in ways that differ from what the standard cosmological model suggests.