Astronomers have long been fascinated by the mysterious “little red dots” discovered by NASA’s James Webb Space Telescope. Less than six months after starting science operations, the telescope revealed numerous small, red objects in the sky that scientists are struggling to understand.
Researchers recently compiled a large sample of these objects, known as “Little Red Dots” (LRDs), which existed during the first 1.5 billion years after the Big Bang. To date, nearly all LRDs contain signs of growing supermassive black holes.
Led by Colby College’s Dale Kocevski, the team used publicly available Webb data to identify these red sources in various surveys and discovered that they emerge in large numbers around 600 million years after the Big Bang before declining rapidly.
The LRDs showed signs of gas rapidly orbiting at high speeds – a sign of an accretion disk around a supermassive black hole. This suggests that many LRDs are actually accreting black holes, also known as active galactic nuclei (AGN).
Contrary to initial fears, the team’s research supports existing theories, and much of the light coming from these objects is thought to be from accreting black holes rather than stars.
The discovery has sparked further questions about LRDs, such as why they are not seen at lower redshifts. One possible explanation is that star formation within a galaxy expands outward from the nucleus, reducing the amount of gas deposited near the accreting black hole and causing it to lose its LRD status.
Astronomers will continue to study these enigmatic objects using multiple approaches, including examining mid-infrared properties and searching for more accreting black holes.
Source: https://science.nasa.gov/missions/webb/newfound-galaxy-class-may-indicate-early-black-hole-growth-webb-finds