The best estimates indicate that he mass of the unseen member in the binary system Cygnus X-1 is approximately 9 solar masses, which is significantly greater than that of a white dwarf or neutron star (Wald 112). Other proof that the second object was a black hole and not a neutron star was the regularity of "pulses- or emissions of light. Neutron stars proceed at regular intervals while the unknown object in Cygnus X-1 was completely random. A more recent discovery in the effects of a binary system with a black hole are gravitational waves. As the stars in a binary system get closer to one another, they give off gravitational waves. These waves are ripples of space-time itself (unlike light rays, which travel through space-time). They propagate at the speed of light and are not altered by the matter through which they pass. They affect the objects they pass through by alternately compressing and rarifying them (Richstone 2).
Another place that astrophysicists are looking for black holes are in the center of galaxies. In September of 2001 the Chandra X-ray Observatory, a sophisticated orbiting telescope, detected an X-ray flare from the center of our galaxy (Stenger 1). The intense burst, which indicates the fatal plunge of matter into oblivion, allowed astronomers to estimate the size of the black hole in the center of the Milky Way at no larger than the distance between the sun and Earth. Chandra researchers calculated that the mass at the center of the galaxy, about 2.6 million times that of the sun, fit into a space no larger than 93 million miles across. According to the known laws of physics only a black hole could be that dense. Astronomers theorize that most galactic cores have black holes. One way to study a black hole is for scientists to look for gas swirling around its edges in the accretion disk. Another way to detect the possibility of a black hole is through the microlensing detection technique.
