Ram Pressure Stripping

Class providing models of ram pressure stripping-induced rates of mass loss—the removal of cold interstellar gas from satellite galaxies as they move through the hot intracluster or intragroup medium of their host halo. The ram pressure \(P_\mathrm{ram} = \rho_\mathrm{ICM} v^2\) exerted by the ambient gas on the disc component strips cold gas at a rate (in \(\mathrm{M}_\odot\) Gyr\(^{-1}\)) that depends on the satellite velocity, the host gas density at the satellite’s position, and the restoring pressure from the disc’s self-gravity. This process quenches star formation in satellite galaxies on short timescales.

Default implementation: ramPressureStrippingSimpleCylindrical

Methods

rateMassLoss → double precision

Returns the rate of mass loss (in \(\mathrm{M}_\odot\) Gyr\(^{-1}\)) due to ram pressure stripping of the given component.

  • class(nodeComponent), intent(inout) :: component

ramPressureStrippingSimpleCylindrical

A ram pressure stripping class which applies to systems with cylindrical symmetry (e.g. disks), and computes the mass loss rate to be:

\[\dot{M}_\mathrm{gas, disk} = \hbox{min}\left({\beta \mathcal{F}_\mathrm{hot, host} \over 2 \pi \mathrm{G} \Sigma_\mathrm{gas}(r_\mathrm{half}) \Sigma_\mathrm{total}(r_\mathrm{half})}, R_\mathrm{maximum}\right) {M_\mathrm{gas, disk} \over \tau_\mathrm{dyn, disk}},\]

where \(\mathcal{F}_\mathrm{hot, host}\) is the ram pressure force due to the hot halo of the node’s host (computed using the selected hot halo ram pressure force method; see hotHaloRamPressureForce), \(\Sigma_\mathrm{gas}(r)\) is the gas surface density in the disk, \(\Sigma_\mathrm{total}(r)\) is the total surface density in the disk, \(r_\mathrm{half}\) is the disk half-mass radius, \(M_\mathrm{gas, disk}\) is the total gas mass in the disk, \(\tau_\mathrm{dyn, disk} = r_\mathrm{disk}/v_\mathrm{disk}\) is the dynamical time in the disk, \(\beta=\)[beta] scales the rate of mass loss, and \(R_\mathrm{maximum}=\)[rateFractionalMaximum] controls the maximum allowed rate of mass loss.

(Default implementation)

Parameters

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

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

ramPressureStrippingSimpleSpherical

A simple model of ram pressure stripping in spherically-symmetric systems (e.g. spheroids). The mass loss rate is given by:

\[\dot{M}_\mathrm{gas} = -\hbox{max}(\alpha,R_\mathrm{maximum}) M_\mathrm{gas}/\tau_\mathrm{spheroid},\]

where \(R_\mathrm{maximum}=\)[ramPressureStrippingMassLossRateSpheroidSimpleFractionalRateMax]

\[\alpha = \beta \mathcal{F}_\mathrm{hot,host}/F_\mathrm{gravity},\]

and,

\[F_\mathrm{gravity} = {4\over 3} \rho_\mathrm{gas}(r_{1/2}) {\mathrm{G} M_\mathrm{total}(r_{1/2})\over r_{1/2}}\]

is the gravitational restoring force in the spheroid at the half-mass radius, \(r_\mathrm{1/2}\) (Takeda et al., 1984), \(\beta=\)[beta] scales the rate of mass loss, and \(R_\mathrm{maximum}=\)[rateFractionalMaximum] controls the maximum allowed rate of mass loss.

Parameters

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

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