An international team of astronomers has discovered the formation of spheroids in distant galaxies that resulted from a star explosion in the early Universe using the Atacama Large Millimeter/submillimeter Array(ALMA) telescope, according to an article published Thursday in the academic journal Nature.
The discovery was made under the leadership of the Purple Mountain Observatory (PMO) at the Chinese Academy of Sciences, with significant participation from CEA Paris-Saclay and the University of Tokyo.
In the early Universe, there was a special type of galaxy called a star galaxy. These galaxies were capable of producing new stars and causing rapid and extreme supernova explosions – eventually leading to the formation of supermassive black holes in their cores. The nuclei of most galaxies contain a dense central region composed of many stars called spheroids. However, it was previously unclear how these spheroids form.
In the PMO-led study, scientists used a statistical analysis of the surface brightness distribution of dust emission in the submillimeter range. The data for the analysis were obtained using the ALMA telescope, which observed more than 100 luminous galaxies that have flared up since the cosmic noon epoch, which was approximately 8 to 12 billion years ago and was a period when many galaxies were actively forming stars.
“The analysis showed that most of these high star formation galaxies were inherently spherical rather than disk-shaped,” said Tang Qinghua, an associate research scientist at PMO and corresponding author of the study.
Further numerical modeling showed that the main mechanism for the formation of these spheroids was the simultaneous action of cold gas accretion and galaxy interaction. It was believed that this process was quite common in the early Universe, the period when most spheroids formed.
According to Tan, the study provides the first robust observational evidence that spheroids could have formed directly as a result of intense star formation in the cores of bright galaxies in the early Universe – which could have significantly affected the morphology and evolution of galaxies, eventually forming the elliptical galaxies we observe in the modern Universe.
“In the future, with the use of more advanced observational equipment with higher resolution and sensitivity, scientists may be able to obtain a more complete picture of the galaxy formation process in the early Universe, thereby deepening our understanding of how the entire Universe evolved over time,” Tan said.
