The James Webb space telescope was designed to look back in time and study galaxies that existed shortly after the ‘’Big Bang.’’ In so doing, scientists hoped to gain a better understanding of how the universe has evolved from the earliest cosmological epoch to the present. When Webb first trained its advanced optics and instruments on the early universe, it discovered a new class of astrophysical objects: bright red sources that were dubbed “Little Red Dots.”
Initially, astronomers hypothesized that they could be massive star-forming regions, but this was inconsistent with established cosmological models. In essence, those models predicted that massive galaxies could not have formed less than a billion years after “Big Bang.” This led to the theory that they might be quasars, the bright central regions of galaxies powered by supermassive black holes (SMBHs). This also challenged established models, as it was theorized that SMBHs wouldn’t have had enough time to form either. The study was led by Fabio Pacucci, a Staff Astrophysicist with the Harvard and Smithsonian Center of Astrophysics and the Black Hole Initiative at Harvard University. He was joined by Andrea Ferrara, a professor of cosmology at the Scuola Normale Superiore in Pisa, Italy and Dale D. Kocevski, an associate professor of physics and astronomy at Colby College. The paper detailing their findings, “The Little Red Dots Are Direct Collapse Black Holes,’’ is being reviewed for publication in the journal Nature.
Their research is based on radiation-hydrodynamic (RHD) simulations developed to model the emission properties of Direct Collapse Black Holes (DCBHs), a class of black holes that form directly from clouds of cold gas. This differs from conventional models that predict how black holes form from the collapse of massive stars. These massive stars, a theoretical class known as Population lll, were the first stars in the universe, forming from hydrogen and helium with little to no traces of heavier elements (like metals). They were massive, extremely hot and bright, and very short-lived compared to more modern generations of stars, remaining in their main sequence phase for about 2-5 million years. Over time, these black holes would then merge with other black holes (via galactic mergers and other mechanisms) to form massive black holes (MBHs). However this process could occur only over billions of years, not the few hundred million years between the ‘’Big Bang’’ and the emergence of these galaxies
