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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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NGC 383: This S0 galaxy has a nuclear dust disk. The STIS slits were aligned<br />

parallel to the galaxy major axis, 6 ◦ from the dust disk axis. The weighted mean<br />

observation - model residuals are plotted <strong>in</strong> Figure 4.3 <strong>and</strong> gives a m<strong>in</strong>imum at an<br />

offset of 120 km s −1 , equivalent to a galaxy recessional velocity of 5010 km s −1 . The<br />

model velocity profiles for these observations are shown <strong>in</strong> Figure 4.25. In the ob-<br />

served velocity profile a central velocity gradient is observed which seems as if it may<br />

correspond to gas rotat<strong>in</strong>g <strong>in</strong> the potential generated by a M• > 9 × 10 8 M⊙ black<br />

hole, though the situation is very unclear, a second plot is shown which represents<br />

more closely the profile <strong>in</strong> the very central few spectra, but provides a less good fit<br />

<strong>in</strong> the outer parts.<br />

NGC 541: This cD S0 galaxy has a nuclear dust disk. The STIS slits were aligned<br />

to a mean of the position angles of the central isophotes measured from the WFPC2<br />

images, which vary considerably. The dust disk is almost round so no dust axis can<br />

be def<strong>in</strong>ed. The weighted mean observation - model residuals are plotted <strong>in</strong> Figure<br />

4.4 <strong>and</strong> gives a m<strong>in</strong>imum at an offset of 70 km s −1 , equivalent to a galaxy recessional<br />

velocity of 5428 km s −1 . The model velocity profiles for these observations are shown<br />

<strong>in</strong> Figure 4.26. It is not clear that the modeled velocity profiles match any of the<br />

observed k<strong>in</strong>ematics <strong>in</strong> the nuclear region.<br />

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