The majority of galaxies have a supermassive black hole at their core. And, like our own Milky Way version, most of these black holes are relatively quiet. However, a minority of supermassive black holes are incredibly active, consuming dust, gas, and other matter at an extraordinary rate and emitting large amounts of energy. Scientists call these black holes active galactic nuclei.
Generally, these active galactic nuclei all look the same, with a donut-shaped ring of dust, or a torus, surrounding the black hole. Now, scientists have determined that the tori around active supermassive black holes are actually much smaller than originally theorized. The study will be published in Monthly Notices of the Royal Astronomical Society.
The team used the SOFIA telescope (a Boeing 747SP modified to carry a 100-inch diameter telescope) to examine the infrared emissions of 11 different active galactic nuclei over 100 million light years away. They discovered that the peak infrared emissions are at even longer wavelengths and that the tori are more compact, to the tune of 30%, than scientists originally thought.
While this is certainly an interesting observation, it has larger implications for future detection and observation of black holes. By pinpointing these longer wavelengths that tori absorb and reemit energy at, scientists are able to determine the best way to observe them. Water vapor actually obscures these longer wavelengths within the Earth's atmosphere, so future work on active galactic nuclei should be mostly conducted through SOFIA or other telescopes that operate above our planet's water vapor. The team's next step is to determine whether all of these emissions indeed originate from tori, or whether there's something else within the structure of active galactic nuclei that is responsible for part of these signals.