.. _physics-coolingInfallTorque:

Cooling Infall Torque
=====================

Class providing models of the fraction of angular momentum lost by gas as it falls from the hot halo onto the galaxy. Torques from the dark matter halo, the existing galaxy, and gas dynamical effects can cause infalling gas to lose angular momentum before it joins the disk, thereby producing a more compact disc than would result from purely angular-momentum-conserving infall. The returned fraction of angular momentum loss directly modulates the specific angular momentum assigned to the cooling gas.

**Default implementation:** ``coolingInfallTorqueFixed``

Methods
-------

``fractionAngularMomentumLoss`` → ``double precision``
   Return the fraction of specific angular momentum lost by infalling gas as it travels from the infall radius to the galaxy disk, where torques from the halo, galaxy, or gas dynamics reduce the angular momentum of the accreting gas.

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

.. _physics-coolingInfallTorqueFixed:

``coolingInfallTorqueFixed``
----------------------------

A cooling infall torque class in which a fixed fraction of specific angular momentum is lost from gas as it cools and falls onto the galaxy. The fraction of angular momentum lost during infall is specified by the ``[fractionLossAngularMomentum]`` parameter.

**(Default implementation)**

**Parameters**

* ``[fractionLossAngularMomentum]`` (real; default ``0.3d0``) — Specifies the fraction of angular momentum that is lost from cooling/infalling gas.