A newly discovered black hole has left astronomers perplexed, prompting the question: How can we make sense of this? This peculiar phenomenon, known as the Infinity Galaxy, challenges our understanding of supermassive black holes and their formation. Located in the COSMOS field, this galaxy appears to be sandwiched between two cores, with two compact, reddish bulges separated by a distance of approximately 33,000 light-years. Each bulge contains a staggering 100 billion suns' worth of stars, surrounded by a bright ring or shell of stars. The Keck telescope's spectroscopy revealed strong emission lines from highly ionized atoms, indicating an intense energy source has stripped electrons from these atoms. This spectrum resembles a narrow-line active galactic nucleus, a sign of an actively feeding supermassive black hole. The radio and X-ray data further strengthened this case, as a normal cluster of stars cannot easily explain the observed bright, compact radio emission and strong X-ray output at the same location. The central region of the galaxy is complex and stretched, with tendrils of emission, matching the radio source very well. The researchers, led by Pieter van Dokkum of Yale University and Gabriel Brammer of the University of Copenhagen, have brought in three key kinds of detective evidence: spectroscopy from the Keck telescope, radio observations from the Very Large Array, and X-ray observations from the Chandra X-ray Observatory. The F150W filter, one of Webb's infrared views, shows bright hydrogen emission and nearby nitrogen and sulfur lines, indicating the presence of glowing gas. The team built a "continuum-subtracted" map to isolate the glow from the gas, revealing extended ionized gas spread across the region between the two bulges. The equivalent width of the emission lines reached hundreds to a couple of thousand angstroms in rest-frame equivalent width, suggesting a high concentration of glowing gas with few stars. The authors propose that a nearly head-on collision between two disk galaxies could explain the ringed pattern, forming what astronomers call a collisional ring galaxy. However, other explanations, such as a third faint galaxy hosting the black hole or a black hole stripped from a smaller galaxy, are also considered. The team calls it a "candidate direct-collapse black hole" and wants more detailed spectroscopy and simulations to test whether the gas can collapse into a seed black hole instead of mostly forming stars. The full study was published in The Astrophysical Journal Letters.
