BBKS¶
- class hmf.density_field.transfer_models.BBKS(cosmo, **model_parameters)[source]¶
BBKS (1986) transfer function.
- Parameters:
cosmo (
astropy.cosmology.FLRWinstance) – The cosmology used in the calculation**model_parameters (unpack-dict) – Parameters specific to this model. In this case, available parameters are the following: a, b, c, d, e. To see their default values, check the
_defaultsclass attribute.
Notes
The fit is given as
\[T(k) = \frac{\ln(1+aq)}{aq} \left(1 + bq + (cq)^2 + (dq)^3 + (eq)^4\right)^{-1/4},\]where
\[q = \frac{k}{\Gamma}\]and \(\Gamma = \Omega_{m,0} h\). Note that here k is in units of h/Mpc, which accounts for the extra h in the equations in BBKS.
These equations are taken from BBKS 1986, Eq. G3.
Further modifications can be made in the presence of baryons. With
use_sugiyama_baryons, the form of the Sugiyama (1995) preprint (astro-ph/9412025, Eq. 3.9; also quoted by Liddle et al. 1996, Eq. 6) is used:\[\Gamma \rightarrow \Gamma \exp\left(-\Omega_{b,0}(1 + 1/\Omega_{m,0})\right).\]With
use_liddle_baryons(the default), the published form of Sugiyama (1995, ApJS 100, 281), as quoted by Meiksin, White & Peacock (1999, Eq. 4) and Liddle & Lyth (2000, Eq. 5.14), is used:\[\Gamma \rightarrow \Gamma \exp\left(-\Omega_{b,0}(1 + \sqrt{2h}/\Omega_{m,0})\right).\]The two agree exactly at \(h = 0.5\). If both are set,
use_sugiyama_baryonstakes precedence.Attributes
- references: ClassVar[tuple[str, ...]] = ('Bardeen, J. M., Bond, J. R., Kaiser, N., Szalay, A. S., 1986. ApJ 304, 15. https://ui.adsabs.harvard.edu/abs/1986ApJ...304...15B',)¶
References to cite when this model is used, each a formatted citation string. Subclasses inherit their parent’s references unless they set their own.
Methods