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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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may have some connections with the central eng<strong>in</strong>es. We next discuss correlations<br />

between the nuclear fluxes across many different wave-b<strong>and</strong>s, <strong>and</strong> then correlations<br />

between properties of the host galaxies <strong>and</strong> central eng<strong>in</strong>es.<br />

5.3.1 Are the Broad L<strong>in</strong>es physical?<br />

In Chapter 3 (§3.3.2) we showed that fits to the very central spectra improved with<br />

the <strong>in</strong>clusion of a broad component which we attributed to either a physical broad<br />

l<strong>in</strong>e region or an artifact of fitt<strong>in</strong>g to an asymmetrical l<strong>in</strong>e shape (§3.5.3). It is likely<br />

that both of these factors do <strong>in</strong>deed play a role.<br />

Whittle (1985) found relationships between narrow-l<strong>in</strong>e widths <strong>and</strong> shapes (of<br />

[O III]) <strong>and</strong> the radio properties of the galaxies. If modifications to the velocity pro-<br />

file of the narrow l<strong>in</strong>es <strong>in</strong> the nuclear regions can occur (e.g. from jet <strong>in</strong>teractions <strong>and</strong><br />

outflows) then this may <strong>in</strong>deed modify the l<strong>in</strong>e profiles so that a broad component<br />

would improve the fit. Deeper observations of the sample nuclei are necessary before<br />

we can perform multi-Gaussian fits, such as those described <strong>in</strong> §3.5.4, which would<br />

enable us to better disentangle light from broad emission l<strong>in</strong>e regions to modifica-<br />

tions of the narrow l<strong>in</strong>e shapes, though the results <strong>in</strong> that section suggest models<br />

with a comb<strong>in</strong>ation of asymmetric profiles <strong>and</strong> a broad component provide the best<br />

representation of the central spectra.<br />

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