Title:
Cosmic Rays or Turbulence Can Suppress Cooling Flows
Cosmic Rays or Turbulence Can Suppress Cooling Flows
Speaker:
蘇恭毅 (Kung-Yi Su), PhD, CCA Flatiron Institute
蘇恭毅 (Kung-Yi Su), PhD, CCA Flatiron Institute
Time:
11/09 (Sat.) 7 pm PDT, 8 pm MDT, 9 pm CDT, 10 pm EDT
11/10 (Sun.) 11 am Taiwan
11/09 (Sat.) 7 pm PDT, 8 pm MDT, 9 pm CDT, 10 pm EDT
11/10 (Sun.) 11 am Taiwan
Keywords:
Astronomy, Galaxy, AGN feedback, Cooling flows, Cosmic rays, Turbulence
Astronomy, Galaxy, AGN feedback, Cooling flows, Cosmic rays, Turbulence
Abstract:
The quenching "maintenance" and related "cooling flow" problems are important in galaxies from Milky Way mass through clusters. We investigate this in halos (1e12-1e14 solar mass), using non-cosmological high-resolution hydrodynamic simulations with the FIRE2 (Feedback In Realistic Environments) stellar feedback model. We first focus the various proposed "non-AGN" solution mechanisms, including Type Ia supernovae (SNe), AGB winds, cosmic rays (CR) from SNe, magnetic fields, conduction, or morphological quenching, and show that they do not substantially reduce cooling flows nor maintain "quenched". This all supports the idea that additional physics, e.g., AGN feedback, must be important in massive galaxies, but even the qualitative form of this energetic input remains uncertain. We, therefore, tested different scenarios including thermal heating, momentum injection, cosmic ray injection, or turbulent stirring of the intra-cluster medium (ICM). We explore which scenarios can quench without violating observational constraints on energetics or ICM gas. We show that turbulent stirring or CR injection, can both maintain a 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. Turbulent stirring also mixes condensed core gas into the hot halo. Pure thermal heating or nuclear isotropic momentum injection require larger energy and require fine-tuning to avoid overheating/gas expulsion.
The quenching "maintenance" and related "cooling flow" problems are important in galaxies from Milky Way mass through clusters. We investigate this in halos (1e12-1e14 solar mass), using non-cosmological high-resolution hydrodynamic simulations with the FIRE2 (Feedback In Realistic Environments) stellar feedback model. We first focus the various proposed "non-AGN" solution mechanisms, including Type Ia supernovae (SNe), AGB winds, cosmic rays (CR) from SNe, magnetic fields, conduction, or morphological quenching, and show that they do not substantially reduce cooling flows nor maintain "quenched". This all supports the idea that additional physics, e.g., AGN feedback, must be important in massive galaxies, but even the qualitative form of this energetic input remains uncertain. We, therefore, tested different scenarios including thermal heating, momentum injection, cosmic ray injection, or turbulent stirring of the intra-cluster medium (ICM). We explore which scenarios can quench without violating observational constraints on energetics or ICM gas. We show that turbulent stirring or CR injection, can both maintain a 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. Turbulent stirring also mixes condensed core gas into the hot halo. Pure thermal heating or nuclear isotropic momentum injection require larger energy and require fine-tuning to avoid overheating/gas expulsion.
No comments:
Post a Comment