Dark Matter Halo Mass Loss Rates

Class providing models of the rate of mass loss from dark matter (sub)halos due to tidal stripping and other processes. Returns the rate of change of halo mass (in \(\mathrm{M}_\odot\) Gyr\(^{-1}\)) for a given node. This class is used in combination with tidal stripping models to track the evolution of subhalo masses as they orbit within a host halo.

Default implementation: darkMatterHaloMassLossRateZero

Methods

rate → double precision

Returns the rate of mass loss (in \(\mathrm{M}_\odot\)/Gyr) from node.

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

darkMatterHaloMassLossRateVanDenBosch

A dark matter halo mass loss rate class which uses the algorithm of van den Bosch et al. (2005) to compute the rate of mass loss. Specifically:

\[\dot{M}_\mathrm{node,bound} = -{M_\mathrm{node,bound}\over \tau} \left({M_\mathrm{node,bound} / M_\mathrm{node,parent}}\right)^\zeta,\]

where \(M_\mathrm{node,parent}\) is the mass of the parent node in which the halo lives and

\[\tau = \tau_0 \left({\Delta_\mathrm{vir}(t) \over \Delta(t_0)}\right)^{-1/2} a^{3/2},\]

where \(\Delta_\mathrm{vir}(t)\) is the virial overdensity of halos at time \(t\) and \(a\) is the expansion factor. The fitting parameters, \(\tau_0\) and \(\zeta\) have values of 0.13 Gyr and 0.36 respectively as determined by van den Bosch et al. (2005). Note that van den Bosch et al. (2005) write this expression in a slightly different form since their \(\Delta_\mathrm{vir}\) is defined relative to the critical density rather than the mean density as it is in Galacticus. In both cases, the timescale \(\tau\) simply scales as \(\langle \rho_\mathrm{vir} \rangle ^{-1/2}\) where \(\langle \rho_\mathrm{vir} \rangle\) is the mean virial overdensity of halos.

Parameters

  • [timescaleNormalization] (default 0.13d0) — The mass loss timescale normalization (in Gyr) for the van den Bosch et al. (2005) dark matter halo mass loss rate algorithm.

  • [zeta] (default 0.36d0) — The mass loss scaling with halo mass for the van den Bosch et al. (2005) dark matter halo mass loss rate algorithm.

darkMatterHaloMassLossRateZero

A dark matter halo mass loss rate class which assumes a zero rate of mass loss from dark matter halos.

(Default implementation)