Evidence of a relation between black

Evidence of a relation between black - extreme...

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Evidence of a relation between black-hole mass and bulge properties (sometimes known as the Magorrian relation ) has focussed attention on the co-evolution of nuclei and bulges. Correlations exist with bulge absolute magnitude (often expressed as stellar mass, in the half-percent rule) and velocity dispersion: M = 1.48 ± 0.24 x 10 8 (σ/200 km/s) 4.65 ± 0.48 following papers by Ferrarese and Merritt and Gebhardt et al. (both 2000). A relation of this kind likely means that the bulge initially regulates the formation of a massive black hole, which grows until its dynamical influence reshapes stellar orbits in its vicinity. It is not ruled out that the black holes came first, but the tightness of the correlation (± 50% or so) is suspiciously good for this. The return of STIS promises to give us more points testing this relation in different and more
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Unformatted text preview: extreme environments, after a frustrating hiatus while it was out of service. Recognition of the dichotomy in galaxy color has led to another fascinating aspect to AGN hosts. Fro the SDSS and GALEX surveys, it is clear that the fraction of AGN peaks in the "green valley" between the major sequences of star-forming and passive galaxies. There are too few objects in the valley for there to be many starbursts superiposed on red galaxies, so most of the population there must be involved in a one-time transfer from blue to red sequences. What happens then to make feeding the AGN more efficient? There is also evidence that disk galaxies tend to host less massive black holes, seen in AGN acreting at a higher Eddington ratio than more massive ones in elliptical galaxies. This could also be connected to the major transformations in the green valley....
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This note was uploaded on 11/10/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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