14
June
2017
|
06:25 PM
America/New_York

SOFIA enables new discoveries on the characterization of active galactic nuclei dust tori

Universities Space Research Association staff scientist Enrique Lopez-Rodriguez, at the SOFIA Science Center, together with researchers at the University of Texas, San Antonio found that the dust surrounding active, ravenous black holes is much more compact than previously thought. Using observations from NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), the team determined the characteristics and properties of the torus-shaped dust structures at the far-infrared wavelengths.               

Image courtesy: NASA/SOFIA/Lynette Cook                                                                                         

Black holes and their behavior have been for a long time, an enigma for scientists. Found in abundance in the universe, these gravity-pulling, star-devouring  black holes have always been known to exist in distant galaxies. And a supermassive black hole--the largest type of black hole--on the order of hundreds of thousands to billions of solar masses, is found in the center of almost all currently known massive galaxies.  

Many of these black holes are relatively quiet and inactive, like the one at the center of our Milky Way galaxy. However, some supermassive black holes are currently consuming significant amounts of material that are being drawn into them, resulting in the emission of huge amounts of energy. These active black holes are called active galactic nuclei.

Previous studies have suggested that all active galactic nuclei have essentially the same structure. Models indicate that active galactic nuclei have a donut-shaped dust structure, known as a torus, surrounding the supermassive black hole. Using the instrument called the Faint Object infraRed CAmera for the SOFIA Telescope, FORCAST, the team observed the infrared emissions around 11 supermassive black holes in active galactic nuclei located at distances of 100 million light years and more, and determined the size, opacity, and distribution of dust in each torus.

In a paper published in the Monthly Notices of the Royal Astronomical Society, the team reports that the tori are 30 per cent smaller than predicted and that the peak infrared emission is at even longer infrared wavelengths than previously estimated. The implication is that the dust obscuring the central black hole is more compact that previously thought.

They also indicate that active galactic nuclei radiate most of their energy at wavelengths that are not observable from the ground because the energy is absorbed by water vapor in Earth’s atmosphere. SOFIA flies above 99 per cent of the Earth’s water vapor, enabling the research group to characterize the properties of the torus-shaped dust structures at far-infrared wavelengths.

“Using SOFIA, we were able to obtain the most spatially detailed observations possible at these wavelengths, allowing us to make new discoveries on the characterization of active galactic nuclei dust tori,” said Lindsay Fuller, graduate student at the University of Texas San Antonio and lead author of the published paper.

Enrique Lopez-Rodriguez, principal investigator of this project and Universities Space Research Association staff scientist at the SOFIA Science Center said, “Next, our goal will be to use SOFIA to observe a larger sample of active galactic nuclei, and at longer wavelengths. That will allow us to put tighter constraints on the physical structure of the dusty environment surrounding the active galactic nuclei.”

SOFIA is a Boeing 747SP jetliner modified to carry a 100-inch diameter telescope. It is a joint project of NASA and the German Aerospace Center, DLR. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science and mission operations in cooperation with the Universities Space Research Association headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart. The aircraft is based at NASA’s Armstrong Flight Research Center's Hangar 703, in Palmdale, California.

Article adapted from the Zee News media and Deccan Chronicle, with inputs from NASA

Image Courtesy: NASA