The Warped Nuclear Disk of Radio Galaxy 3C 449

• Published in: The Astrophysical journal 2006-05, Vol.643 (1), p.101-111
• Main Authors: Tremblay, Grant R, Quillen, Alice C, Floyd, David J. E, Noel-Storr, Jacob, Baum, Stefi A, Axon, David, O’Dea, Christopher P, Chiaberge, Marco, Macchetto, F. Duccio, Sparks, William B, Miley, George K, Capetti, Alessandro, Madrid, Juan P, Perlman, Eric
• Format: Article
• Language: English
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/502643

Among radio galaxies containing nuclear dust disks, the bipolar jet axis is generally observed to be perpendicular to the disk major axis. The FR I radio source 3C 449 is an outlier to this statistical majority, as it possesses a nearly parallel jet/disk orientation on the sky. We examine the 600 pc dusty disk in this galaxy with images from the Hubble Space Telescope. We find that a 1.6 km/0.7 km color map of the disk exhibits a twist in its isocolor contours (isochromes). We model the color map 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 precessional models or a torque on the disk arising from a possible binary black hole in the AGN causes precession on a timescale that is too long to account for the predicted disk morphology. However, we estimate that the pressure in the X-ray-emitting interstellar medium is large enough to perturb the disk, and we argue that jet-driven anisotropy in the excited ISM may be the cause of the warp. In this way, the warped disk in 3C 449 may be a new manifestation of feedback from an active galactic nucleus.