Diagram 8
Astronomers have a new place to search for wandering black holes.
At the center of each spiral galaxy is a supermassive black hole. Diagram 8 (right) shows two spiral galaxies seen from Earth in a particular orientation. The two orbital planes of the galaxies are parallel so that the galaxies face each other. Gravity attracts the less massive black hole of the smaller galaxy toward the more massive black hole of the other galaxy.
Now presume that another galaxy or galaxy cluster is beyond the space between the two galaxies of Diagram 8. The background galaxies or clusters are shown in blue and yellow. In other words, the space between the two galaxies is illuminated by another galaxy or cluster in the background.
This scenario offers an excellent opportunity for astronomers to watch a supermassive black hole in motion. Astronomers know that the less massive black hole will be in motion toward the other black hole. They know they can use the optical data analysis technique used to spot extra-solar planets to track the movement of the black hole!
That optical technique is simple. Astronomers fix a telescope on a distant star and record the amount of light received. They analyze the received light on a computer. Whenever they detect slight decreases in light that are systematically moving across the star, they theorize that it's a planet. If the systematic decreases in light are consistent with a planet trajectory, a new planet is announced.
So too in the case of wandering supermassive black holes. When the light from a background light source (a galaxy) decreases, astronomers will know that the supermassive black hole is moving. It blocks light from the background light source.
Alternatively, astronomers may observe a supermassive black hole causing gravitational lensing. The light from the background light source will bend around the supermassive black hole as it moves through space. Some of the light will fall into the black hole.
Either way, astronomers have a new hunting ground. They should search their astronomical data collections for two galaxies oriented as in Diagram 8 that have a background light source like a galaxy or cluster. Then they should fix their telescopes on that position.
This is a revolutionary opportunity to study the movement of supermassive black holes!
At the center of each spiral galaxy is a supermassive black hole. Diagram 8 (right) shows two spiral galaxies seen from Earth in a particular orientation. The two orbital planes of the galaxies are parallel so that the galaxies face each other. Gravity attracts the less massive black hole of the smaller galaxy toward the more massive black hole of the other galaxy.
Now presume that another galaxy or galaxy cluster is beyond the space between the two galaxies of Diagram 8. The background galaxies or clusters are shown in blue and yellow. In other words, the space between the two galaxies is illuminated by another galaxy or cluster in the background.
This scenario offers an excellent opportunity for astronomers to watch a supermassive black hole in motion. Astronomers know that the less massive black hole will be in motion toward the other black hole. They know they can use the optical data analysis technique used to spot extra-solar planets to track the movement of the black hole!
That optical technique is simple. Astronomers fix a telescope on a distant star and record the amount of light received. They analyze the received light on a computer. Whenever they detect slight decreases in light that are systematically moving across the star, they theorize that it's a planet. If the systematic decreases in light are consistent with a planet trajectory, a new planet is announced.
So too in the case of wandering supermassive black holes. When the light from a background light source (a galaxy) decreases, astronomers will know that the supermassive black hole is moving. It blocks light from the background light source.
Alternatively, astronomers may observe a supermassive black hole causing gravitational lensing. The light from the background light source will bend around the supermassive black hole as it moves through space. Some of the light will fall into the black hole.
Either way, astronomers have a new hunting ground. They should search their astronomical data collections for two galaxies oriented as in Diagram 8 that have a background light source like a galaxy or cluster. Then they should fix their telescopes on that position.
This is a revolutionary opportunity to study the movement of supermassive black holes!
Copyright, 2011.
Wade Hobbs, Jr.
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