Abstract
Jets are observed to stir up multiphase turbulence in the interstellar medium
as well as far beyond the host galaxy. Here we present detailed simulations of this process.
We evolve the hydrodynamics equations with optically thin cooling for a 3D Kelvin
Helmholtz setup with one initial cold cloud. The cloud is quickly disrupted, but the fragments
remain cold and are spread throughout our simulation box. A scale free isotropic
Kolmogorov power spectrum is built up first on the large scales, and reaches almost down
to the grid scale after the simulation time of ten million years.
We find a pronounced peak in the temperature distribution at 14,000K. The luminosity of
the gas in this peak is correlated with the energy. We interpret this as a realisation of the
shock ionisation scenario. The interplay between shock heating and radiative cooling establishes
the equilibrium temperature. This is close to the observed emission in some Narrow
Line Regions. We also confirm the shift of the phase equilibrium, i.e. a lower (higher) level
of turbulence produces a higher (lower) abundance of cold gas. The effect could plausibly
lead to a high level of cold gas condensation in the cocoons of extragalactic jets, explaining
the so called Alignment Effect.
as well as far beyond the host galaxy. Here we present detailed simulations of this process.
We evolve the hydrodynamics equations with optically thin cooling for a 3D Kelvin
Helmholtz setup with one initial cold cloud. The cloud is quickly disrupted, but the fragments
remain cold and are spread throughout our simulation box. A scale free isotropic
Kolmogorov power spectrum is built up first on the large scales, and reaches almost down
to the grid scale after the simulation time of ten million years.
We find a pronounced peak in the temperature distribution at 14,000K. The luminosity of
the gas in this peak is correlated with the energy. We interpret this as a realisation of the
shock ionisation scenario. The interplay between shock heating and radiative cooling establishes
the equilibrium temperature. This is close to the observed emission in some Narrow
Line Regions. We also confirm the shift of the phase equilibrium, i.e. a lower (higher) level
of turbulence produces a higher (lower) abundance of cold gas. The effect could plausibly
lead to a high level of cold gas condensation in the cocoons of extragalactic jets, explaining
the so called Alignment Effect.
| Original language | English |
|---|---|
| Title of host publication | The central kiloparsec: Active Galactic Nuclei and their hosts |
| Publisher | Memorie della Societa Astronomica Italiana |
| Pages | 1162-1165 |
| Number of pages | 4 |
| Volume | 79 |
| Publication status | Published - 6 Jun 2008 |
Keywords
- Galaxies: active, Galaxies: jets, Hydrodynamics: turbulence, Hydrodynamics: simulations