Black Hole Winds

Class providing models of the mechanical power in winds driven by active galactic nuclei (AGN) that couples to the surrounding galaxy. AGN-driven winds can heat or expel gas from the host galaxy, suppressing star formation. The wind power typically scales with the black hole accretion rate and radiative efficiency.

Default implementation: blackHoleWindCiotti2009

Methods

power → double precision

Computes the power in the wind that couples to the surrounding galaxy.

• class(nodeComponentBlackHole), intent(inout) :: blackHole

blackHoleWindCiotti2009

A black hole winds class based (loosely) on the model of Ciotti et al. (2009). The wind power is given by:

\[L_\mathrm{w} = \epsilon_\mathrm{w} \epsilon_\mathrm{r} f_\mathrm{w} \dot{M}_\bullet \mathrm{c}^2,\]

where \(\dot{M}_\bullet\) is the black hole accretion rate, \(\epsilon_\mathrm{w}=\)[efficiencyWind] is an overall efficiency parameter, \(\epsilon_\mathrm{r}\) is the radiative efficiency of the accretion flow if [efficiencyWindScalesWithEfficiencyRadiative]=true, and \(1\) otherwise, and \(f_\mathrm{w}\) represents the fraction of the wind power that is coupled to the surrounding galaxy.

The model for \(f_\mathrm{w}\) is inspired by Ciotti et al. (2009) who state: If the pressure corresponding to the momentum flow within the jet or wind is much greater than the pressure in the ambient gas, very little mass, momentum and kinetic energy is taken from it and deposited in that ambient gas. But when the [ratio of ISM to wind pressure] approaches unity, the “working surface” has been reached and the jet or wind discharges its content.

The energy density (pressure) in the wind at some radius \(r\) in the galaxy is simply \(\epsilon_\mathrm{w} \epsilon_\mathrm{r} \dot{M} \mathrm{c}^2 / 4 \pi r^2 v_\mathrm{w}\) (i.e. the energy input into a shell over time \(\delta t\), \(\epsilon_\mathrm{w} \epsilon_\mathrm{r} \dot{M} \mathrm{c}^2 \delta t\), divided by the volume of the shell occupied by the wind in time \(\delta t\), \(4 \pi r^2 v_\mathrm{w} \delta t\)) where \(v_\mathrm{w}\) is the wind velocity (assumed fixed at \(10^4\) km/s). The corresponding ISM pressure is just \((3/2) \mathrm{k}T \rho(r)/m_\mathrm{H}\) where \(T\) is the ISM temperature (assumed fixed at \(10^4\) K) and \(\rho\) is the ISM density. We approximate that the spheroid ISM density as \(3 M/4/\pi/r^3\), where \(M\) is the total gas mass in the spheroid, such that we find a ratio of ISM to wind pressures of:

\[\frac{P_\mathrm{ISM}}{P_\mathrm{w}} = (3/2) \mathrm{k}T \rho(r)/m_\mathrm{H} \left/ \frac{\epsilon_\mathrm{w} \epsilon_\mathrm{r} \dot{M} \mathrm{c}^2}{4 \pi r^2 v_\mathrm{w}} \right. .\]

We then smoothly interpolate \(f_\mathrm{w}\) across the transition as:

\[\begin{split}f_\mathrm{w} = \left\{ \begin{array}{ll} 0 & \hbox{if } x \le 0 \\ 3 x^2 - 2 x^3 & \hbox{if } 0 < x < 1 \\ 1 & \hbox{if } x \ge 1, \end{array} \right.\end{split}\]

where \(x=P_\mathrm{ISM}/P_\mathrm{w}-1/2\).

(Default implementation)

Parameters

• [efficiencyWind] (default 2.4d-3) — The efficiency of the black hole accretion-driven wind: \(L_\mathrm{wind} = \epsilon_\mathrm{wind} \dot{M}_\bullet \clight^2\).

• [efficiencyWindScalesWithEfficiencyRadiative] (default .false.) — Specifies whether the black hole wind efficiency should scale with the radiative efficiency of the accretion disk.

blackHoleWindSimple

Models AGN accretion-driven winds in which a fixed fraction of the accreted rest-mass energy is injected as a mechanical wind into the host galaxy. The wind power is proportional to the black hole accretion rate, with the coupling efficiency set by the [efficiencyWind] parameter.

Methods

• calculationReset — Reset memoized calculations.

Parameters

• [efficiencyWind] (default 2.2157d-3) — The coupling efficiency of the black hole accretion-driven wind, defined as the fraction of the accreted rest-mass energy that is deposited as kinetic or thermal energy into the surrounding gas via AGN-driven outflows.

• [redshiftReionization] (default 9.97d0) — The redshift of reionization below which baryonic accretion onto halos is suppressed due to the ionizing background heating the intergalactic medium and preventing gas from accreting onto low-mass halos.

• [opticalDepthReionization] — The optical depth to electron scattering below which baryonic accretion is suppressed.

• [velocitySuppressionReionization] (default 35.0d0) — The velocity scale below which baryonic accretion is suppressed.

• [accretionNegativeAllowed] (default .true.) — Specifies whether negative accretion (mass loss) is allowed in the simple halo accretion model.

• [accretionNewGrowthOnly] (default .false.) — Specifies whether accretion from the IGM is allowed only when a halo is growing past its previous greatest mass.

• [acceptedStateCount] (default 100) — The number of states to use in acceptance rate statistics.

• [timeStepRelative] (default 0.1d0) — The maximum allowed relative change in time for a single step in the evolution of a node.

• [timeStepAbsolute] (default 1.0d0) — The maximum allowed absolute change in time (in Gyr) for a single step in the evolution of a node.

• [timeStepMinimum] (default 1.0d-6) — The smallest timestep to use in profiling ODE solver steps.

• [timeStepMaximum] (default 1.0d+1) — The largest timestep to use in profiling ODE solver steps.

• [timeStepPointsPerDecade] (default 3) — The number of bins per decade of timestep to use when profiling ODE solver steps.

• [wavelength] (default 1.0d4) — The wavelength of the photon packet (in AA).

• [wavelengthMinimum] (default 0.5d4) — The minimum wavelength of the photon packet (in AA).

• [wavelengthMaximum] (default 2.0d4) — The maximum wavelength of the photon packet (in AA).

• [luminosity] (default 1.0d0) — The luminosity of the photon packet (in \(L_\odot\)).

• [massRatioMajorMerger] (default 0.25d0) — The mass ratio above which mergers are considered to be “major”.

• [destinationGasMinorMerger] (default var_str('spheroid')) — The component to which satellite galaxy gas moves to as a result of a minor merger.

• [destinationStarsMinorMerger] (default var_str('spheroid')) — The component to which satellite galaxy stars move to as a result of a minor merger.

• [degreesOfFreedom] (default 3.0d0) — Number of degrees of freedom to assume when computing the energy density of cooling gas in the “simple” cooling time class.

• [timeScale] (default 1.0d0) — The timescale (in Gyr) for cooling in the simple cooling rate model.

• [reionizationRedshift] (default 9.97d0) — The redshift of reionization in the simple IGM state model.

• [reionizationTemperature] (default 1.0d4) — The post-reionization temperature (in units of Kelvin) in the simple IGM state model.

• [preReionizationTemperature] (default 10.0d0) — The pre-reionization temperature (in units of Kelvin) in the simple IGM state model.

• [useFormationHalo] (default .false.) — Specifies whether or not the “formation halo” should be used when solving for the radii of galaxies.

• [solveForInactiveProperties] (default .true.) — If true, galactic structure is solved for during evaluation of inactive property integrals. Otherwise, structure is not solved for during this phase—this should only be used if the inactive property integrands do not depend on galactic structure.

• [rateFractionalMaximum] (default 10.0d0) — The maximum fractional mass loss rate per dynamical time in the simple model of mass loss due to tidal stripping.

• [beta] (default 1.0d0) — The scaling factor which multiplies the tidal mass loss rate.

• [OmegaMatter] (default 0.3153d0) — The density of matter in the Universe in units of the critical density.

• [OmegaBaryon] (default 0.04930d0) — The density of baryons in the Universe in units of the critical density.

• [OmegaDarkEnergy] (default 0.6847d0) — The density of dark energy in the Universe in units of the critical density.

• [temperatureCMB] (default 2.72548d0) — The present day temperature of the CMB in units of Kelvin.

• [HubbleConstant] (default 67.36d0) — The present day value of the Hubble parameter in units of km/s/Mpc.