Spiral morphology in an intensely star-forming disk galaxy over 12 billion years ago
Characteristics of the spiral at the beginning of the Universe
It is believed that the early assembly of galaxies produced disturbed and asymmetrical objects. Morphological features seen in nearby galaxies, such as stellar disks, bulges, and spiral arms, take time to form and would be disrupted by the frequent galaxy mergers that occurred in early times. Tsukui and Iguchi identified a distant galaxy containing a gas disk 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 characteristics 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, disk, and spiral arms. It is not known 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] the gas kinematics show a sharp increase in speed near the center of the galaxy 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 compact central structure such as a bulge, a rotating gas disk, and either spiral arms or tidal tails. These features formed 1.4 billion years after the Big Bang, well before the peak of cosmic star formation.