Astronomers in Pasadena, California recently discovered a whopping 18 tidal disruption events (TDEs) that had previously gone undetected. TDEs occur when the tidal forces of a supermassive black hole overwhelm a star’s gravity and tear it apart. The immense amounts of energy these events give off can be detected, and they are thought to occur once every 10,000 to 100,000 years in any given galaxy.
These TDEs were found in dusty galaxies, where dust can obscure many wavelengths of radiation, making them harder to detect. However, long infrared wavelengths are much less susceptible to scattering and absorption, allowing the researchers to find these hidden events.
Previously, most TDEs were detected in the optical and X-ray bands, but these methods can still miss some events, particularly in dust-rich galaxies. Dust and gas in a black hole’s accretion disk also don’t help with detection, making it challenging for astronomers to find these elusive events.
The discovery of these TDEs in the infrared has significant implications for the actual TDE population, which was previously hard to estimate based on those that had only been detected in the optical and X-ray bands. The researchers suggest that the “missing energy” of TDEs, which was thought to be a discrepancy in observed energy output, may have simply been obscured by dust and gas, rather than actually missing.
The closest known TDE to Earth was also included in the 18 newly discovered events. This TDE resides in a particularly dusty star-forming galaxy, which would have made it almost impossible to detect without infrared observations. This challenges the previous assumption that TDEs were most likely to occur in galaxies where star formation has ceased or nearly ceased, as they may be hidden by dust in star-forming galaxies.
These findings represent a potential breakthrough in TDE research, with future surveys, such as the Legacy Survey of Space and Time (LSST) at the Vera Rubin Observatory, expected to find hundreds, even thousands, of TDEs every year. The researchers believe that their work will provide new insights into TDE demographics in the local Universe and allows them to probe the properties of a previously overlooked class of TDEs.