The Role of Shock Heating in AGN Feedback PDF
Preview The Role of Shock Heating in AGN Feedback
The Role of Shock Heating in AGN Feedback S. W. Randall - CfA P. Nulsen, W. Forman, S. Giacintucci, M. Sun, C. Jones, E. Churazov, L. David, R. Kraft, M. Donahue, E. Blanton, A. Simionescu, & N. Werner S. W. Randall CXC Clusters, Boston 2011 Peterson+ 2001 Early XMM-Newton and Chandra observations showed that there is not as much gas cooling to low temperatures as predicted in “cool core” clusters Gas must be heated, most likely through feedback with the central AGN (McNamara & Nulsen 2007) S. W. Randall CXC Clusters, Boston 2011 The AGN Feedback Cycle Jets inflate Flows onto Drives AGN cavities, Gas cools AGN outburst driving shocks Slows mass Cavities and Cavities rise flow, and Slows cooling shocks heat buoyantly heating ICM S. W. Randall CXC Clusters, Boston 2011 Centaurus A X-ray false color image Kraft+ 08, Croston+ 09 S. W. Randall CXC Clusters, Boston 2011 S. W. Randall CXC Clusters, Boston 2011 Why Do We Care About Feedback? Solution to the “cooling flow problem” Affects the structure and evolution of clusters and groups Buoyant bubbles redistribute gas and metals Need to understand to use clusters as cosmological probes Regulates black hole growth rate Regulates star formation rate => galaxy evolution theory S. W. Randall CXC Clusters, Boston 2011 Does It Work? Cavities are easy to detect, and are seen in many systems (clusters, groups, and galaxies) Generally, the total energy of the cavities (estimated from PV work) is sufficient to offset cooling (Birzan+04, Dunn & Fabian 04, Rafferty+06) However, the details of how and where the cavities release their energy to heat the ICM are poorly understood S. W. Randall CXC Clusters, Boston 2011 Outer Bubble Inner Bubble Inner Bubble Blanton+09,10,11 David+09 Forman+07 Finoguenov+08 S. W. Randall CXC Clusters, Boston 2011 What About Shocks? Expect a total shock energy similar to cavities, especially soon after the outburst Basic shock physics is well understood Shocks will naturally heat the ICM isotropically, and more strongly near the AGN, as required for feedback S. W. Randall CXC Clusters, Boston 2011 M87 (Virgo Cluster) Forman+07 Broad energy band Hard band only S. W. Randall CXC Clusters, Boston 2011
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