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Cosmic Rays or Turbulence can Suppress Cooling Flows (Where Thermal Heating or Momentum Injection Fail)

Su, Kung-Yi and Hopkins, Philip F. and Hayward, Christopher C. and Faucher-Giguère, Claude-André and Kereš, Dušan and Ma, Xiangcheng and Orr, Matthew E. and Chan, T. K. and Robles, Victor H. (2018) Cosmic Rays or Turbulence can Suppress Cooling Flows (Where Thermal Heating or Momentum Injection Fail). . (Unpublished)

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The quenching `maintenance' and `cooling flow' problems are important from the Milky Way through massive cluster elliptical galaxies. Previous work has shown that some source of energy beyond that from stars and pure magnetohydrodynamic processes is required, perhaps from AGN, but even the qualitative form of this energetic input remains uncertain. Different scenarios include thermal `heating,' direct wind or momentum injection, cosmic ray heating or pressure support, or turbulent `stirring' of the intra-cluster medium (ICM). We investigate these in 1012−1014M⊙ halos using high-resolution non-cosmological simulations with the FIRE-2 (Feedback In Realistic Environments) stellar feedback model, including simplified toy energy-injection models, where we arbitrarily vary the strength, injection scale, and physical form of the energy. We explore which scenarios can quench without violating observational constraints on energetics or ICM gas. We show that turbulent stirring in the central ∼100kpc, or cosmic-ray injection, can both maintain a stable low-SFR halo for >Gyr timescales with modest energy input, by providing a non-thermal pressure which stably lowers the core density and cooling rates. In both cases, associated thermal-heating processes are negligible. Turbulent stirring preserves cool-core features while mixing condensed core gas into the hotter halo and is by far the most energy efficient model. Pure thermal heating or nuclear isotropic momentum injection require vastly larger energy, are less efficient in lower-mass halos, easily over-heat cores, and require fine-tuning to avoid driving unphysical temperature gradients or gas expulsion from the halo center.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Hopkins, Philip F.0000-0003-3729-1684
Hayward, Christopher C.0000-0003-4073-3236
Kereš, Dušan0000-0002-1666-7067
Ma, Xiangcheng0000-0001-8091-2349
Orr, Matthew E.0000-0003-1053-3081
Chan, T. K.0000-0003-2544-054X
Additional Information:We thank Eliot Quataert for conversations and collaboration. Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. The Flatiron Institute is supported by the Simons Foundation. CAFG was supported by NSF through grants AST-1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grant 17-ATP17-0067, by CXO through grant TM7-18007, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. DK was supported by NSF grant AST-1715101 and the Cottrell Scholar Award from the Research Corporation for Science Advancement. TKC was supported by NSF grant AST-1412153. V.H.R. acknowledges support from UC-MEXUS and CONACyT through the postdoctoral fellowship. Numerical calculations were run on the Caltech compute cluster “Wheeler,” allocations from XSEDE TG-AST130039 and PRAC NSF.1713353 supported by the NSF, and NASA HEC SMD-16-7592.
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
Simons FoundationUNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
University of California Institute for Mexico and the United States (UC MEXUS)UNSPECIFIED
Consejo Nacional de Ciencia y Tecnología (CONACYT)UNSPECIFIED
Subject Keywords:methods: numerical — MHD — galaxy:evolution — ISM: structure — ISM: jets and outflows
Record Number:CaltechAUTHORS:20190206-105651728
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92733
Deposited By: George Porter
Deposited On:07 Feb 2019 15:52
Last Modified:03 Oct 2019 20:47

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