The awakening of black holes | Max-Planck-Gesellschaft https://www.mpg.de/16804183/the-awakening-of-black-holes
Using the SRG/eROSITA all-sky survey data, scientists at the Max Planck Institute for Extraterrestrial Physics have found two previously quiescent galaxies that now show quasi-periodic eruptions. The nuclei of these galaxies light up in X-rays every few hours, reaching peak luminosities comparable to that of an entire galaxy. The origin of this pulsating behaviour is unclear. A possible cause is a stellar object orbiting the central black hole. As these galaxies are relatively close and small, this discovery could help scientists to better understand how black holes are activated in low-mass galaxies.
galaxies Nature, published 29 April 2021 eROSITA website