When a star wanders too close to a black hole, an object with gravity so intense that not even light can escape, tidal forces shred it like dough caught in a mixer's beaters. This event, known as a tidal disruption event (TDE), unleashes a powerful flare of radiation. Such a flare, cataloged as AT2018cqh, erupted in a dwarf galaxy — a small stellar system with relatively low mass. Its brightness climbed for 550 days, then settled into a persistent X-ray glow. Analysis of spectra (the decomposition of light into wavelengths, revealing the composition and motion of matter) and photometry — precise measurements of an object's brightness over time — showed that the flare's source was an intermediate-mass black hole: its mass is tens of thousands of times that of the Sun. Such objects are extremely rare and fill an evolutionary gap between stellar-mass black holes (formed from collapsing massive stars) and the supermassive black holes that reside in the centers of galaxies. The most surprising finding: these intermediate-mass 'seeds' may have served as the embryos from which the giants shining today in galactic cores grew. The AT2018cqh flare not only exposed a hidden black hole but also confirmed that the method of detecting tidal disruption events is effective for hunting the missing link in the black hole hierarchy.
Intermediate-mass black holes could have been the 'seeds' from which supermassive black holes at the centers of galaxies grew.
In the movie Interstellar, the heroes dive into a wormhole, but if their ship had gotten too close to a black hole, it would have met the same fate: tidal forces would have stretched and torn it into cosmic spaghetti.