Detecting The Event Horizon of A Black Hole Using Radio Technology

Discovering and viewing the event horizon of a black hole has always been a goal of scientists since their speculation. They have intrigued the minds of many, as no one knows exactly what happens at the event horizon, or even if they truly exist as black holes could very much be taken as a mistake for something else. Many attempts in the past have been made to discover and view the event horizons of nearby black holes, and technology is still being used today in newer ways to extend this search and possibly reach the actual goal by finally finding the event horizons and viewing them. Newer methods have been proposed, but have yet to be tested.

Firstly, the black hole itself is difficult to view, as it is “not visible to the outside world” and “no signal can reach the region of space-time outside” a certain “Schwarzchild radius,” and the boundary in between this radius becomes known as the event horizon (Dolan, 2001). In a sense, discovering the black hole or its event horizon become synonymous where detecting the event horizon to the black hole leads to the proving and discovery of the black hole itself. Instead, x-ray and UV vision is used to detect and see black holes generally (Dolan, 2001). Another article discusses how the Hubble Space Telescope was able to collect data from a decade ago and how that data is being synthesized to “observe what seems to be the last gasp emitted by gaseous material spiraling Cygnus X-1, a suspected black hole 6,000 light-years from Earth” (Cowen, 2001). Blobs of hot gas supposedly spiraling and/or orbiting a black hole, radiate pulses of ultraviolet light, growing fainter rapidly and then just simply disappearing, lead to the expectation that these gases are about to enter the event horizon. Furthermore, the light emitted from these gasses “grows dimmer because the black hole’s gravity shifts the light to longer and longer wavelengths,” where radiation actually stops by the time the gas enters the black hole (Cowen, 2001).

Before using technology to find the event horizon, mathematical algorithms were created to find these event horizons, where they would make sense in theory. Once these algorithms were created, they would then be used in conjunction with radio technology, to detect and locate the black hole and its respective event horizon. In specific, Jonathan Thornburg uses “3 + 1 ADM formalism” to conduct calculations that help find the “apparent horizons in numerically-computed spacetimes” (Thornburg, 2001).

A new method of spacing out telescopes a great distance apart, and using the images collected by each of the three telescopes in a unifying manner has allowed scientists to attain a resolution much greater than the one provided by the Hubble Space Telescope. The new technique is called Very Long Baseline Interferometry and it exploits the phenomenon of interference, where multiple light waves are superimposed to amplify a signal (Wanjek, 2008). The technique of VLBI has been used to detect a massive radio source at the center of the Milky Way Galaxy, Sagittarius A. Very Long Baseline Interferometry allowed for three telescopes to achieve Sagittarius A’s first size measurement (Schwarzschild, 2008).

The James Clerk Maxwell Radio Telescope, served as one of three radio telescopes to form an array as part of Very Long Baseline Interferometry to achieve the first size measurement of Sagittarius A, a nearby black hole (Schwarzchild, 2008).

Works Cited

Cowen, R. “Peering At Black Holes: An Eventful Look.” Science News 159.3 (2001): 38.

Dolan, Joseph F. “How To Find A Stellar Black Hole.” Science 292.5519 (2001): 1079-1080.

Schwarzschild, Bertram. “Radio Interferometry Measures The Black Hole At The Milky Way’s Center.” Physics Today 61.11 (2008): 14-18.

Thornburg, Jonathan. “Event And Apparent Horizon Finders For 3+1 Numerical Relativity.” Living Reviews In Relativity 10.4 (2007): 1-68.

Wanjek, Christopher. “Radio Dishes Tune In To Event Horizon.” Mercury 37.4 (2008): 9.