NASA’s SOFIA Discovers Cool Dust Around Active Black Holes

Scientists have recently found that the dust that surrounds active and hungry black holes is much more compact than previously thought. The research was conducted by a team from the University of Texas San Antonio with the help of data from NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA).

According to Phys.org, some supermassive black holes are at present consuming significant amounts of materials and emitting huge amounts of energy -- such black holes are known as active galactic nuclei. Earlier studies have indicated that all active galactic nuclei have a similar structure essentially -- a donut-shaped dust structure called torus that surrounds the supermassive black hole.

Now with the help of SOFIA’s Faint Object infraRed CAmera Telescope (FORCAST), the research team studied the infrared emissions around 11 supermassive black holes in active galactic nuclei. These were located at distances of 100 million light-years and more.

The researchers determined the opacity, size and distribution of dust in each torus and found that the tori are 30 percent smaller than predicted. Moreover, the peak infrared emission is at even longer infrared wavelengths than calculated previously. The findings imply that the dust obscuring the central black hole is more compact than scientists had thought before.

The research also suggests that active galactic nuclei emanate most of their energy at wavelengths that cannot be observed from the ground on Earth because the water vapor present in the planet’s atmosphere absorbs the energy.

“Using SOFIA, we were able to obtain the most spatially detailed observations possible at these wavelengths,” lead author of the paper published in the Monthly Notices of the Royal Astronomical Society, Lindsay Fuller, said. “This allowed us to make new discoveries on the characterization of active galactic nuclei dust tori.”

SOFIA is a Boeing 747SP jetliner that carries a 100-inch diameter telescope. It flies above 99 percent of the Earth's water vapor.