Cold Mode Accretion Infall Rates

Class providing models of the cold-mode infall rate (in \(\mathrm{M}_\odot\) Gyr\(^{-1}\)) at which gas streams along cold filaments directly into the galaxy, bypassing the hot atmosphere. Cold-mode accretion is thought to dominate at high redshift and in lower-mass halos where the virial temperature is too low to maintain a stable hot atmosphere. The cold-mode infall rate supplements the hot-mode cooling rate to give the total gas supply available for star formation.

Default implementation: coldModeInfallRateDynamicalTime

Methods

infallRate → double precision

Returns the cold mode infall rate for node (in units of \(\mathrm{M}_\odot\) Gyr\(^{-1}\)).

  • type(treeNode), intent(inout) :: node

coldModeInfallRateDynamicalTime

A cold mode infall rate class in which the infall rate from the cold mode is given by

\[\dot{M}_\mathrm{infall, cold mode} = f_\mathrm{infall, cold mode}{M_\mathrm{cold mode} \over \tau_\mathrm{dyn}},\]

where \(f_\mathrm{infall, cold mode}=\)[dynamicalRateFraction].

(Default implementation)

Parameters

  • [efficiency] (default 0.01d0) — The efficiency of star formation for the dynamical time method.

  • [exponentVelocity] (default -1.50d0) — The velocity exponent for star formation for the dynamical time method.

  • [timescaleMinimum] (default 1.0d-3) — The minimum allowed timescale for star formation (in Gyr) in the dynamical time prescription, preventing unphysically short formation timescales in high-density or high-velocity systems.

  • [dynamicalRateFraction] (default 2.0d0) — The fraction of the inverse dynamical time to use as the rate for infall of the cold mode component.