Methods of Detection

X-Ray This method of detection uses the accretion disk and how it has twinjets of streaming high-powered particles that are perpendicular to this disk. This makes the black holes x-ray emitters. To find these they use x-ray telescopes. They find a strong source of x-rays and they trace it back to the origin. When they do this sometimes they find a tiny source with a large mass which means a black hole.
	Redshifted Objects This is very similar to the Doppler effect. When a car is coming towards you and honking its horn you hear it at a higher pitch than normal, when an object is moving towards you, the light rays from it seem to have a higher frequency thus turning red light into yellow light and infrared objects into visible objects. That is called blueshifting. It is the same with redshifting but opposite because if the object is moving away from you, yellow light becomes red light and a x-ray source could become visible. They use this knowledge to find black holes by calculating the redshift of one side of the object and the blueshift of the other. From this they can get an idea of how fast the object is rotating and then get an idea of the mass. If the equation is right and the object is small enough and moving fast enough then they have found a black hole.
Quasars These are located in the oldest part of the universe. They are unbelievably bright objects that look just like stars and are about 10 million solar masses. Quasars fluctuate irregularly and their diameter changes very quickly. They are so big that in order for the diameter to change so much matter would have to be going faster than the speed of light, which is impossible. The only possible conclusion is that they must be small so they can't be stars. They must be black holes that have accretion disks that put out tremendous amounts of energy.
	Wobbling Star This is detected when a star in a binary system (two stars orbiting around each other) has no partner but is still orbiting something. The star appears to wobble. You can not say that the star is orbiting a black hole just by this evidence alone because it could be orbiting a white dwarf, a neutron star, or a black hole. How do scientists determine which one it is? They look at how closely the star is orbiting and if it is orbiting very tightly then it is very likely it is a black hole.
Galactic Turning Point These have to do with the super massive black holes. When astronomers saw a galaxy that was shooting out particles at very high speeds very similar to the jets that come form accretion disks they took a closer look at the core of the galaxy and they found that stars were revolving very fast around the cores. By calculating their speed they judged that the core had to be the mass of a couple of million suns but it was not there. Obviously a black hole. In another galaxy astronomers looked at the cores of galaxies that weren't emitting energy. They found the same thing: big mass and small space at the cores. In some cases later on they found that some of these cores were quasars. Thus black holes.
	Gravitational Waves This is the final method of detection. Many scientists are working on gravitational wave theories because they would absolutely prove the existence of black holes. Gravitational waves are covered in the Related Topics section, but in brief they are waves that propagate at the speed of light and warp spacetime as they move. Only massive objects such as binary star or black hole systems have enough energy to create gravitational waves, therefore the existence of these waves would prove the existence of black holes.
Note: The pictures are just showing the evolution of the telescope, they are not referring to the articles. Just that all methods of detection use some sort of telescope.

Recent Research

	Black hole is the ultimate Niagara Falls 1992- A black hole called GRS 1915+105 spews out the same amount of water that is in Lake Superior every half-hour. GRS 1915+105 is 40,000 light-years away and is a 25mile wide shear that has compressed 10 times the mass the sun. From this black hole scientists found that x-rays come form the inner part of the gas disk which is up to 400miles wide. This gas disk can get up to 30million degrees Fahrenheit. This plus the rotating gravity of the black hole or the magnetic fields causes the black hole to puff in and out until it finally gives way and the black hole explodes into a flare that sends out a shot of the infrared light.
Space-time distortion in space by black holes 1997- On November 6,1997 NASA's Rossi X-ray Timing Explorer reported that it had observed a black hole that is frame dragging, which means it is dragging space and time around itself. In simpler terms the black hole is distorting hot X-ray emitting gas that is close by it. In doing this X-rays are peaking at periods that match the frame-dragging predictions of general relativity. This observation is very important to science because Einstein's theory has never been proven before. Scientist have to study this siting very carefully to determine weather it is really a black hole. Joseph Lense and Hans Thirring first predicted that the frame-dragging effect really existed in 1918 and thus far it has not been proven. Italian astronomers reported the possible detection of frame dragging around another type of very dense objects that spin quite rapidly shortly after this initial incident was reported.
	New discovery in space: Mid-Sized black hole 2000- NASA's Chandra X-ray space observatory has found a new type of black hole. It is located in galaxy M82 that is 10billion light years away. It is called the "missing link" because it is right in the middle of the two sizes of black holes that have been found before. This black hole is no less than 500 times the mass of our sun. It is not a classic one because it is not in the center of the universe. The black hole has an immense disk of glowing gas around it that is only found in supermassive black holes. Scientists have now found three other Mid-sized black holes. Their sizes range from 117to 8500 times the sun's mass. The black hole in galaxy M82 is still growing and very rapidly to. What causes this is that the black hole feeds of the interstellar gas that is constantly being ejected by the many new stars that are forming in this galaxy. It is predicted that the back hole will find its way to the center of the universe and eventually become a supermassive black hole.
There is definitely a black hole in the Milky Way 2001- Scientists have predicted for a long time that there is a large black hole in the center of our Milky Way because there is in many other galaxies. Scientists have found that there is a mass of about 2.5million suns near by tracking a jet of gas that arcs near to the center of the galaxy. Many years ago a radio source was spotted by Sagittarius A, that is 1000 times brighter than the sun. At that time they were not sure whether that meant there was a black hole or not. They have now confirmed that this is a black hole by tracking very closely the motion of the stars. This mass is localized to within a region of space only about 100 times larger than our solar system.