Uplift, Feedback, and Buoyancy: Radio Lobe Dynamics in NGC 4472

Gendron-Marsolais, M.; Kraft, R. P.; Bogdan, A.; Hlavacek-Larrondo, J.; Forman, W. R.; Jones, C.; Su, Y.; Nulsen, P.; Randall, S. W.; Roediger, E.

Abstract

© 2017. The American Astronomical Society. All rights reserved. We present results from deep (380 ks) Chandra observations of the active galactic nucleus (AGN) outburst in the massive early-type galaxy NGC 4472. We detect cavities in the gas coincident with the radio lobes and estimate the eastern and western lobe enthalpy to be (1.1 ± 0.5) × 10 56 erg and (3 ± 1) × 10 56 erg and the average power required to inflate the lobes to be (1.8 ± 0.9) × 10 41 erg s -1 and (6 ± 3) × 10 41 erg s -1 , respectively. We also detect enhanced X-ray rims around the radio lobes with sharp surface brightness discontinuities between the shells and the ambient gas. The temperature of the gas in the shells is less than that of the ambient medium, suggesting that they are not AGN-driven shocks but rather gas uplifted from the core by the buoyant rise of the radio bubbles. We estimate the energy required to lift the gas to be up to (1.1 ± 0.3) × 10 56 erg and (3 ± 1) × 10 56 erg for the eastern and western rims, respectively, constituting a significant fraction of the total outburst energy. A more conservative estimate suggests that the gas in the rim was uplifted at a smaller distance, requiring only 20%-25% of this energy. In either case, if a significant fraction of this uplift energy is thermalized via hydrodynamic instabilities or thermal conduction, our results suggest that it could be an important source of heating in cool core clusters and groups. We also find evidence for a central abundance drop in NGC 4472. The iron abundance profile shows that the region along the cavity system has a lower metallicity than the surrounding undisturbed gas, similar to the central region. This also shows that bubbles have lifted low-metallicity gas from the center.

Citation

Gendron-Marsolais, M., Kraft, R. P., Bogdan, A., Hlavacek-Larrondo, J., Forman, W. R., Jones, C., Su, Y., Nulsen, P., Randall, S. W., & Roediger, E. (2017). Uplift, Feedback, and Buoyancy: Radio Lobe Dynamics in NGC 4472. The Astrophysical journal, 848(1), 26. https://doi.org/10.3847/1538-4357/aa8a6f

• Journal Article Type: Article
• Acceptance Date: Sep 1, 2017
• Online Publication Date: Oct 9, 2017
• Publication Date: Oct 6, 2017
• Deposit Date: Apr 10, 2018
• Publicly Available Date: Apr 11, 2018
• Journal: The Astrophysical Journal
• Print ISSN: 0004-637X
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 848
• Issue: 1
• Pages: 26
• DOI: https://doi.org/10.3847/1538-4357/aa8a6f
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Public URL: https://hull-repository.worktribe.com/output/773616
• Publisher URL: http://iopscience.iop.org/article/10.3847/1538-4357/aa8a6f/meta
• Related Public URLs: https://arxiv.org/abs/1710.04235
• Additional Information: Journal title: The Astrophysical Journal; Article type: paper; Article title: Uplift, Feedback, and Buoyancy: Radio Lobe Dynamics in NGC 4472; Copyright information: © 2017. The American Astronomical Society. All rights reserved.; Date received: 2017-04-18; Date accepted: 2017-09-01; Online publication date: 2017-10-06
• Contract Date: Apr 10, 2018