Spiral features in the early Universe
The early assembly of galaxies is thought to have produced disturbed and asymmetric objects. Morphological features seen in nearby galaxies, such as stellar disks, bulges, and spiral arms, require time to form and would be disturbed by the frequent galaxy mergers that occurred at early times. Tsukui and Iguchi identified a distant galaxy containing a disk of gas with a spiral morphology. The galaxy also has a compact central mass concentration due to a combination of a supermassive black hole and a possible stellar bulge. These features must have formed within 1.4 billion years after the Big Bang.
Science, abe9680, this issue p. 1201
Spiral galaxies have distinct internal structures, including a stellar bulge, a disk, and spiral arms. It is unknown when in cosmic history these structures formed. In this study, we analyzed observations of BRI 1335–0417, an intensely star-forming galaxy in the distant Universe, at a redshift of 4.41. The [C ii] gas kinematics shows a steep velocity rise near the galaxy center and has a two-armed spiral morphology, which extends from about 2 to 5 kiloparsecs in radius. We interpret these features as due to a central compact structure such as a bulge, a rotating gas disk, and either spiral arms or tidal tails. These features had formed within 1.4 billion years after the Big Bang, long before the peak of cosmic star formation.