M-sigma Relation

M-sigma Relation

The M–sigma (or M–σ) relation is an empirical correlation between the stellar velocity dispersion σ of a galaxy bulge and the mass M of the supermassive black hole at the galaxy's center.

The M–σ relation was first presented in 1999 during a conference at the Institut d'astrophysique de Paris in France. The proposed form of the relation, which was called the "Faber-Jackson law for black holes", was

frac{M}{10^8M_odot} approx 3.1left(frac{sigma}{200~{rm km}~{rm s}^{-1}}right)^4.

Publication of the relation in a refereed journal, by two groups, took place the following year. One recent study, based on a complete sample of published black hole masses in nearby galaxies, gives

frac{M}{10^8M_odot} approx 1.9left(frac{sigma}{200~{rm km}~{rm s}^{-1}}right)^{5.1}.

Earlier work had demonstrated a possible relationship between galaxy luminosity and black hole mass, but that relationship had a large scatter. The much smaller scatter of the M–σ relation is generally interpreted to imply some source of mechanical feedback between the growth of supermassive black holes and the growth of galaxy bulges, although the source of this feedback is still uncertain.

Discovery of the M–σ relation was taken by many astronomers to imply that supermassive black holes are fundamental components of galaxies. Prior to about 2000, the main concern had been the simple detection of black holes, while afterward the interest changed to understanding the role of supermassive black holes as a critical component of galaxies. This led to the main uses of the relation to estimate black hole masses in galaxies that are too distant for direct mass measurements to be made, and to assay the overall black hole content of the Universe.

Read more about M-sigma Relation:  Origin, Importance, See Also

Famous quotes containing the word relation:

    In relation to God, we are like a thief who has burgled the house of a kindly householder and been allowed to keep some of the gold. From the point of view of the lawful owner this gold is a gift; From the point of view of the burglar it is a theft. He must go and give it back. It is the same with our existence. We have stolen a little of God’s being to make it ours. God has made us a gift of it. But we have stolen it. We must return it.
    Simone Weil (1909–1943)