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Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

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detection of the broad component is flux limited. The broad components have a mean<br />

velocity dispersion of 1349 ±345km s −1 <strong>and</strong>, assum<strong>in</strong>g an orig<strong>in</strong> <strong>in</strong> Hα are redshifted<br />

by an average of 486 ± 443km s −1 (Chapter 3). The broad components could be<br />

a consequence of non-Gaussian l<strong>in</strong>e profiles with w<strong>in</strong>gs or from physical broad l<strong>in</strong>e<br />

regions (Chapter 5).<br />

What can be said about the masses of the black holes <strong>in</strong> these radio galaxies<br />

based on the gas k<strong>in</strong>ematics? In Chapter 4, we compared the observed profiles<br />

to model profiles from th<strong>in</strong> gas disks <strong>in</strong> gravitational potentials <strong>in</strong>clud<strong>in</strong>g no black<br />

hole, <strong>and</strong> 1 × 10 8 M⊙ <strong>and</strong> 9 × 10 8 M⊙ black holes.<br />

In 6 of 19 galaxies for which we produced th<strong>in</strong> disk models we could not identify<br />

any of the observed k<strong>in</strong>ematics with the models. For 3 of the rema<strong>in</strong><strong>in</strong>g 13 galaxies<br />

we observed a signature compatible with a black hole <strong>in</strong> the range 1×10 8 M⊙ < M• <<br />

9 ×10 8 M⊙, for 5 we observe k<strong>in</strong>ematic signatures compatible with M• ∼ > 9 ×108 M⊙.<br />

NGC 4261 has a profile compatible with a ∼ 1×10 8 M⊙ black hole, though this result<br />

is highly unreliable due to observational problems. These masses are compatible with<br />

the predictions of the M• − σc relationship of Merritt & Ferrarese (2001), however<br />

we do not consider them to be reliable mass determ<strong>in</strong>ations as we f<strong>in</strong>d unsettled<br />

motions <strong>in</strong> the gas play a very significant role <strong>in</strong> the observed k<strong>in</strong>ematics. The three<br />

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