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

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

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


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) × 1056 erg and (3 ± 1) × 1056 erg and the average power required to inflate the lobes to be (1.8 ± 0.9) × 1041 erg s-1 and (6 ± 3) × 1041 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) × 1056 erg and (3 ± 1) × 1056 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.

Original languageEnglish
Article number26
JournalAstrophysical Journal
Issue number1
StatePublished - Oct 10 2017

Bibliographical note

Funding Information:
M.L.G.M. is supported by NASA grants GO1-12160X and NAS8-03060, as well as by NSERC through the Postgraduate Scholarships-Doctoral Program (PGS D) and Université de Montréal physics department. M.L.G.M. thanks H. Intema for useful discussions on radio data. J.H.L. is supported by NSERC through the discovery grant and Canada Research Chair programs, as well as FRQNT.

Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.


  • X-rays: galaxies
  • galaxies: clusters: individual (NGC 4472)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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