.. _physics-nuclearStarClusterGrowthRates:

Nuclear Star Cluster Growth Rates
=================================

Class providing models of the rate (in :math:`\mathrm{M}_\odot \, \mathrm{Gyr}^{-1}`) of gas inflow onto the nuclear star cluster at the center of a galaxy---mass transported inward from the surrounding disk or spheroid by dynamical instabilities, torques, or stellar migration. This inflow feeds both star formation and, potentially, black hole accretion in the nuclear region. Implementations depend on galaxy structural properties such as disk mass, scale radius, and velocity dispersion, and are expected to be particularly important during periods of elevated star formation activity or following mergers.

**Default implementation:** ``nuclearStarClusterGrowthRatesAntonini2015``

Methods
-------

``rate`` → ``double precision``
   Returns the rate (in units of :math:`\mathrm{M}_\odot` Gyr\ :math:`^{-1}`) of gas inflow onto the nuclear star cluster component of ``node``.

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

.. _physics-nuclearStarClusterGrowthRatesAntonini2015:

``nuclearStarClusterGrowthRatesAntonini2015``
---------------------------------------------

A gas inflow rate implementing the model of :cite:p:`antonini_coevolution_2015` for galactic :term:`NSC`.

.. math::

   \dot{M}_\mathrm{gas}^\mathrm{NSC} = A_\mathrm{res}\dot{M}_\star^\mathrm{spheroid},

where :math:`A_\mathrm{res}=`\ ``[efficiency]`` is a free parameter, and :math:`\dot{M}_\star^\mathrm{spheroid}` is the star formation rate of the spheroid component.

**(Default implementation)**

**Parameters**

* ``[efficiency]`` (default ``1.0d-2``) — Parameter controlling the rate of the gas inflow onto the nuclear star cluster.