Scientists using data from NASA’s Neil Gehrels Swift Observatory have discovered a pair of monster black holes that are disrupting a cloud of gas in the center of a galaxy. This event, known as AT 2021hdr, is recurring every few months and is believed to be caused by the black holes interacting with the gas cloud as they orbit each other. The oscillating pattern in the light from the system led researchers to publish a paper in Astronomy and Astrophysics, detailing their findings.
The dual black holes are located in the galaxy 2MASX J21240027+3409114, one billion light-years away in the constellation Cygnus. They are relatively close together, at a distance of 16 billion miles apart, with a combined mass of 40 million times that of the Sun. It is estimated that the black holes complete an orbit every 130 days and will eventually collide and merge in approximately 70,000 years.
AT 2021hdr was first observed in March 2021 by the ZTF at the Palomar Observatory in California and was identified as an intriguing source by ALeRCE, a team that utilizes artificial intelligence tools to flag significant events in the night sky. Subsequent observations by ZTF revealed outbursts from AT 2021hdr every 60 to 90 days, prompting further investigation into the nature of the source.
Researchers have been observing AT 2021hdr using the Swift observatory since November 2022, which has helped them determine that the binary produces oscillations in ultraviolet and X-ray light that correspond to those seen in the visible range by ZTF. By considering various models, including normal galactic activity and tidal disruption events, the team settled on the explanation of a gas cloud being tidally disrupted by the black holes, causing the observed fluctuations in light.
Ongoing observations of AT 2021hdr will help scientists better understand the system and improve their models. Additionally, the researchers are interested in studying the galaxy containing the black holes, which is currently undergoing a merger with another nearby galaxy. The discoveries made through these observations highlight the ongoing scientific contributions of the Swift observatory as it approaches its 20th anniversary.
The study of AT 2021hdr showcases the importance of combining data from different observatories and utilizing advanced technology such as AI to uncover new phenomena in the universe. This research sheds light on the complex interactions between black holes and their surrounding environment, providing valuable insights into the dynamics of galaxies and the evolution of cosmic structures. Through continued observations and analysis, scientists hope to further unravel the mysteries of these monstrous black holes and the fascinating events occurring in their vicinity.