A team of researchers, led by Caltech, has made significant discoveries about an obscure class of galaxies known as Compact Symmetric Objects (CSOs). These active galaxies host supermassive black holes at their cores, from which two jets travel at high speeds in opposite directions. Contrary to previous beliefs that CSOs are young galaxies whose jets evolve over millions of years, the team's findings suggest that CSOs lead relatively short lives.
Greg Taylor, a Distinguished Professor of Physics and Astronomy at The University of New Mexico, highlighted the unusual distribution of CSOs, stating, "One of the big problems with the CSOs is that there are just too many of them." The team, including Anthony (Tony) Readhead, Robinson Professor of Astronomy, Emeritus at Caltech, discovered that CSOs are not young but constitute a distinct species with a lifespan of thousands of years.
The research involved reviewing past observations of over 3,000 CSO candidates and identifying 64 confirmed CSOs, shedding light on their unique characteristics. Evan Sheldahl, a UNM Ph.D. student, who played a key role in the research, expressed optimism about expanding the sample of CSOs to further understand their behavior.
The team's analysis revealed that CSO jets expel for 5,000 years or less before ceasing. Vikram Ravi, assistant professor of astronomy at Caltech, explained, "The CSO jets are very energetic jets but they seem to shut off." The scientists attribute the short-lived jets to tidal disruption events (TDEs), where a single star is devoured by a supermassive black hole, channeling energy into the jets.
Readhead's initial hypothesis in the 1990s, suggesting that TDEs fuel CSOs, gained traction after years of observation and research. By 2020, the team's investigations confirmed CSOs as a distinct family with unique characteristics, differentiating them from larger galaxies with longer-lasting jets.
The team's findings provide new insights into the interaction between massive stars and supermassive black holes, offering a novel approach to studying these celestial phenomena. Readhead emphasized the significance of studying CSOs on shorter timescales, providing a new laboratory for exploring supermassive black holes.
The research, published in three papers in The Astrophysical Journal, was funded by organizations like NSF, NASA, Caltech, and the Max Planck Institute for Radio Astronomy in Bonn, Germany. The discoveries about CSOs open up a new avenue for understanding the complexities of galaxies and supermassive black holes in the universe.