How much black matters is in the cosmos?

Answer 1

Dark Matter
Nearly 50 years ago, Fritz Zwicky realized that clusters of galaxies consisted predominantly of matter in some nonluminous form. The search for dark matter has dominated cosmology for half a century. Precise measurements were obtained over 20 years ago, when dark matter was first mapped in galaxy halos. Only recently has the existence of dark matter over much larger scales than even galaxy clusters been confirmed.
There is at most an amount of dark matter in the disk equal to the amount of luminous matter. A more conservative estimate might place the amount of dark matter at about 25 percent of the amount of luminous matter. In fact, this additional component of matter need be nothing very exotic.

What could the dark matter be? The dark matter in the disk most likely consists of very dim stars, such as white and even black dwarfs. White dwarfs are the destiny of stars like the sun, attained when the nuclear fuel supply is exhausted. A typical white dwarf has a mass of about 0.6 the mass of the sun but a size smaller than that of the earth. It formed as the hot core of a planetary nebula, the final luminous phase of stellar evolution when the envelope of a red giant is ejected as the core burns the last remnants of nuclear fuel. A white dwarf fades slowly to oblivion as it cools down to become a black dwarf.

A useful measure of mass is obtained by taking the ratio of the mass of all stars to the to the luminosity emitted by all stars, in a volume of a few hundred parsecs around the sun. If the typical star near the sun was equal in mass to the sun, the ratio of total mass to total light would be unity, larger than unity if the typical star was less massive, and smaller than unity for more massive stars. Since the resulting ratio is found to be 2 for nearby stars, in solar units of solar mass (M) to solar luminosity (L): M/L we conclude that the average star near the sun is slightly less massive than the sun. In the solar vicinity, there is little necessity for any dark matter other than the dark dwarfs. The first real surprise emerges in the outermost parts of galaxies, known as galaxy halos. Here, there is negligible luminosity, yet there are occasional orbiting gas clouds, both atomic and ionized, which allow one to measure rotation velocities and distances. The rotation velocity is found not to decrease with increasing distance from the galactic center. This constancy of velocity implies that the galaxy's cumulative mass must continue to increase with the radial distance from the center of the galaxy, even though the cumulative amount of light levels off.

Just how much additional mass is in the halo? This rise appears to stop at about 50 kiloparsecs, where the halo seems to be truncated. We infer that the mass--to--luminosity ratio of the galaxy, including its disk halo, is about five times larger than estimated for the luminous inner region, or equal to about 50. This is the first solid, incontrovertible evidence for dark matter. The rotation velocities throughout many spiral galaxies have been measured, and all reveal dominance by dark matter.

Moving further afield, the mass-to-light ratio can also be evaluated by studying galaxy pairs, groups, and clusters. In each case, one measures velocities and length scales, from which one determines of the total mass required to provide the necessary self-gravity to stop the system from flying apart. The inferred ratio of mass to luminosity is about 100M/L for galaxy pairs, which typically have separations of about 100 kiloparsecs. The mass-to-luminosity ratio increases to 300 for groups and clusters of galaxies over a length scale of about 1 megaparsec. Over this scale, 95 percent of the measured mass is dark.

Answer 2

Including black jacks? Approx 15 tonnes.

Answer 3

If i heard you right I would say endless.

Answer 4

that question has been asked again--i think u shud remove one of these