A Lecture and a Show

Dr. Nick Devereux’s talk about black holes accompanied by planetarium visuals

On Nov. 7, 2019, Embry-Riddle’s own Dr. Nick Devereux presented his show Supermassive Black Holes in the Local Universe which gave evidence of the suspected existence of black holes existing at the center of galaxies, even at the center of the Milky Way Galaxy. He also mentioned the recently famous galaxy M87, the subject of the first image ever obtained with the Event Horizon Telescope.

Devereux began with talking about how monumental it was to be able to discuss such a topic that was only speculation years ago. He then proceeded to mention that the known knowledge of the universe “is intimately linked to technological advances in telescope design and associated instrumentation.” Modern large telescopes like the Keck Observatory and the European Southern Observatory are able to track individual stars orbiting the supermassive black hole at the center of the galaxy. 

With these telescopes images had been taken of space and had captured a white band produced by a billion different stars which define the disk of the Milky Way. Within the band is the galactic center which is masked behind layers of interstellar dust. When the center was viewed, infrared technology was used and produced that the distance was about 30,000 lightyears away. 

The individual stars that were observed at the center were monitored closely to find their speed and the size of their orbit around the black hole, astronomers were able to estimate the mass of the black hole to be several million solar masses only with the use of the acceleration due to gravity, the radius of the orbit and the stellar velocity.

“Accretion is a process that describes how matter falls into a black hole. The black holes paradoxically also eject matter in a form of a pair of jets,” described Devereux. The famous M87 Galaxy had been observed with a jet that points in the direction of Earth which caused some issues with visibility compared to if the jet was angled. 

The image that made M87 famous was taken with a number of telescopes all over the world, which combined would make a single telescope with the same diameter of the Earth. The image captured hot gas that swirled around the event horizon of the black hole. The diameter of the event horizon allowed astronomers to determine the black hole mass. Inside the event horizon, the escape velocity exceeds the speed of light, which explains why we are unable to see light at the center of a black hole.

Since the prediction of black holes existing at the center of the galaxies, technology to observe them have come a long way and it is still improving.