.. _physics-hotHaloRamPressureForce:

Hot Halo Ram Pressure Force
===========================

Class providing models of the ram pressure force (in :math:`(\mathrm{km\,s}^{-1})^2 \mathrm{M}_\odot \mathrm{Mpc}^{-3}`) exerted on a satellite galaxy by the hot gas atmosphere of its host halo. Ram pressure is generated by the motion of the satellite through the ambient hot gas and can strip cold gas and hot gas from the satellite. The force depends on the satellite orbital velocity relative to the hot gas and the local hot gas density at the satellite position, and is balanced against the restoring gravitational force of the satellite to determine the stripping radius.

**Default implementation:** ``hotHaloRamPressureForceFont2008``

Methods
-------

``force`` → ``double precision``
   Return the ram pressure force acting on ``node`` (in units of (km/s)\ :math:`^2\mathrm{M}_\odot`/Mpc\ :math:`^3`).

   * ``type(treeNode), intent(inout) :: node``

.. _physics-hotHaloRamPressureForceFont2008:

``hotHaloRamPressureForceFont2008``
-----------------------------------

A hot halo ram pressure force class which follows the model of :cite:t:`font_colours_2008`. Specifically, the ram pressure force is

.. math::

   \mathcal{F}_\mathrm{ram, hot, host} = \rho_\mathrm{hot, host}(r_\mathrm{peri}) v^2(r_\mathrm{peri}),

where :math:`\rho_\mathrm{hot, host}(r)` is the hot halo density profile of the node's host halo, :math:`v(r)` is the orbital velocity of the node in that host, and :math:`r_\mathrm{peri}` is the pericentric radius of the node's orbit.

**(Default implementation)**

**Parameters**

* ``[formFactor]`` (default ``2.0d0``) — The form factor appearing in the gravitational binding force (per unit area) in the ram pressure stripping model of :cite:author:`font_colours_2008` (:cite:year:`font_colours_2008`; their eqn. 4).
* ``[solverFailureIsFatal]`` (default ``.true.``) — If true, failure to bracket the ram pressure radius is fatal.

.. _physics-hotHaloRamPressureForceOrbitalPosition:

``hotHaloRamPressureForceOrbitalPosition``
------------------------------------------

A hot halo ram pressure force class which computes the force based on the current orbital position within the host halo. Specifically, the ram pressure force is

.. math::

   \mathcal{F}_\mathrm{ram, hot, host} = \rho_\mathrm{hot, host}(r) v^2(r),

where :math:`\rho_\mathrm{hot, host}(r)` is the hot halo density profile of the node's host halo, :math:`v(r)` is the orbital velocity of the node in that host, and :math:`r` is the instantaneous radius of the node's orbit.

.. _physics-hotHaloRamPressureForceRelativePosition:

``hotHaloRamPressureForceRelativePosition``
-------------------------------------------

A hot halo ram pressure force class which computes the force based on the current position relative to the host halo. Specifically, the ram pressure force is

.. math::

   \mathcal{F}_\mathrm{ram, hot, host} = \rho_\mathrm{hot, host}(r) v^2(r),

where :math:`\rho_\mathrm{hot, host}(r)` is the hot halo density profile of the nodes host halo, :math:`v(r)` is the orbital velocity of the node in that host, and :math:`r` is the instantaneous distance to the host halo.

.. _physics-hotHaloRamPressureForceZero:

``hotHaloRamPressureForceZero``
-------------------------------

A hot halo ram pressure force class which assumes a zero ram pressure force due to the hot halo.