On December 18, 2024, NASA researchers announced the discovery of a black hole in galaxy NGC 5084 that appears to be misaligned with its host galaxy. This finding challenges conventional understanding, as most supermassive black holes spin in concert with their galaxies.
NGC 5084, identified centuries ago by William Herschel, revealed its unusual black hole properties through a novel technique called SAUNAS (Selective Amplification of Ultra Noisy Astronomical Signal). This method allowed researchers to detect low-brightness X-ray emissions previously masked by other radiation sources.
Upon analyzing archival data from the Chandra X-ray Observatory, the team observed four large X-ray plumes extending from the galaxy's center. Two of these plumes align with the galactic plane, while the other two extend above and below it. The presence of four plumes is uncommon, suggesting significant disturbances in the galaxy's history.
Further investigations using the Hubble Space Telescope and the Atacama Large Millimeter Array (ALMA) revealed a dusty inner disk rotating at a 90-degree angle to the rest of NGC 5084. Radio observations from the NRAO's Expanded Very Large Array corroborated these findings.
Lead author Alejandro Serrano Borlaff described the discovery as akin to examining a crime scene with multiple types of light, which unveiled the complex history of NGC 5084. Coauthor Pamela Marcum noted the exceptional nature of detecting two pairs of X-ray plumes, providing unique insights into the galaxy's evolution.
The unusual structure of the plumes and the tilted dusty disk suggest that NGC 5084 may have experienced a disturbance, possibly from a collision with another galaxy. The SAUNAS technique has proven effective in revitalizing old data, indicating the potential for further discoveries in well-studied galaxies.