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Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

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hole masses for these galaxies. The scale of the r<strong>and</strong>om motions <strong>in</strong> these galaxies is<br />

so great that we have no reason to believe that the gas <strong>in</strong> the center is only affected<br />

by the smooth gravitational potential of the stars <strong>and</strong> central black hole. More likely<br />

is that these profiles are <strong>in</strong>dicat<strong>in</strong>g the presence of a supermassive black hole on these<br />

mass scales, but that the actual mass may vary considerably from any attempt to<br />

best fit the nuclear slope.<br />

The three rema<strong>in</strong><strong>in</strong>g galaxies are of some <strong>in</strong>terest: <strong>in</strong> NGC 4335 <strong>and</strong> NGC 5141 the<br />

gas is the more settled <strong>in</strong>to a smooth rotation curve than is the case for the majority<br />

of the galaxies (other than the very nearby M84 <strong>and</strong> M87), however <strong>in</strong> both of these<br />

cases we f<strong>in</strong>d that no black hole is necessary to expla<strong>in</strong> the observed k<strong>in</strong>ematics.<br />

In NGC 2329 the central slope of the rotation curve is very shallow compared even<br />

to the ‘no black hole’ model. This suggests that either the gas <strong>in</strong> this galaxy is <strong>in</strong> a<br />

different plane to the one that we were expect<strong>in</strong>g or that there is significant <strong>in</strong>flow<br />

through the disk which is not supported by rotation <strong>in</strong> the gravitational potential.<br />

If this is the case, then this type of motion could also be <strong>in</strong>fluential <strong>in</strong> other nuclei,<br />

particularly as we know that <strong>in</strong> these radio galaxies, the central eng<strong>in</strong>e is be<strong>in</strong>g actively<br />

fueled <strong>and</strong> generat<strong>in</strong>g jets. Possibly NGC 4335 <strong>and</strong> NGC 5141 also h<strong>in</strong>t at this; their<br />

slopes are also slightly too shallow (but with<strong>in</strong> the errors <strong>in</strong> all of the parameters<br />

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