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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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l<strong>in</strong>e flux of the Hα l<strong>in</strong>e <strong>and</strong> columns (6) <strong>and</strong> (7) show its ratio aga<strong>in</strong>st the fluxes of<br />

the [N II]6585 <strong>and</strong> [S II]total (the total flux of the two [S II] l<strong>in</strong>es) respectively. Column<br />

(8) gives the reduced χ 2 (R 2 ) value of the result<strong>in</strong>g fit.<br />

We repeated the fit for the central row of the galaxy NGC 4335 vary<strong>in</strong>g the set of<br />

free parameters <strong>in</strong> order to estimate the reliability of the fits that we had used. We<br />

found that the fit was stable to with<strong>in</strong> one formal error on all quoted parameters when<br />

the velocities, velocity dispersions <strong>and</strong> fluxes of all parameters were fit <strong>in</strong>dependently.<br />

The signal to noise falls off rapidly outside of the very nuclear regions so it is not<br />

possible to consistently run fits with a large number of free parameters. The results<br />

for the nucleus of NGC 4335 satisfy us that we are justified <strong>in</strong> fix<strong>in</strong>g the parameters<br />

<strong>in</strong> the manner that we have chosen, without add<strong>in</strong>g any obvious biases to our results.<br />

3.3.2 Fits with an additional free component<br />

In many cases, as the very central pixels are reached the fit beg<strong>in</strong>s to do a poorer<br />

job of match<strong>in</strong>g the observed profile. In an attempt to improve the fit to the narrow<br />

centers of the l<strong>in</strong>es we tested a fit for the central spectrum of each galaxy <strong>in</strong>clud<strong>in</strong>g<br />

an additional fit component with <strong>in</strong>dependent velocity, velocity dispersion <strong>and</strong> flux,<br />

along with the orig<strong>in</strong>al set of five Gaussians. The fits to the central spectra are<br />

shown <strong>in</strong> Panel (d) of Figures 3.2 to 3.22 (see key <strong>in</strong> Figure 3.1), (i) exclud<strong>in</strong>g <strong>and</strong><br />

65

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