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G. R. Tremblay, A. C. Quillen (University of Rochester), D. J. E. Floyd (Space Telescope Science Institute), J. Noel-Storr (University of Arizona), S. A. Baum, D. J. Axon, C. P. O'Dea (Rochester Institute of Technology), M. Chiaberge (Istituto di Radioastronomia), F. D. Macchetto, W. B. Sparks (Space Telescope Science Institute), G. K. Miley (Leiden Observatory), A. Capetti (Osservatorio Astronomico di Torino), J. P. Madrid (Space Telescope Science Institute), E. Perlman (University of Maryland)
Among radio galaxies containing nuclear dust disks, the bipolar jet axis is generally expected to be perpendicular to the disk major axis. However, the FR I radio source 3C 449, possessing a nearly parallel jet/disk orientation on the sky, is an extreme example of a system that does not conform to this expectation. We examine the 600 pc dusty disk in this galaxy with images from the Hubble Space Telescope. We find that a colormap of the disk exhibits a twist in its isocolor contours (isochromes). We model the colormap by integrating galactic starlight through an absorptive disk, and find that the anomalous twist in the isochromes can be reproduced in the model with a vertically thin, warped disk. The model predicts that the disk is nearly perpendicular to the jet axis within 100 pc of the nucleus. We discuss physical mechanisms capable of causing such a warp. We show that a torque on the disk arising from a possible binary black hole in the AGN or radiation pressure from the AGN causes precession on a timescale that is too long to generate such a warp. However, we estimate that the pressure in the X-ray emitting interstellar medium is large enough to perturb the disk. The warped disk in 3C 449 may be a new manifestation of feedback from an active galactic nucleus.
The author(s) of this abstract have provided an email address for comments about the abstract: grant@pas.rochester.edu
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.