Non-linear models

class camb.nonlinear.NonLinearModel

Abstract base class for non-linear correction models

Variables:Min_kh_nonlinear – (float64) minimum k/h at which to apply non-linear corrections

class camb.nonlinear.Halofit

Bases: camb.nonlinear.NonLinearModel

Various specific approximate non-linear correction models based on HaloFit.

Variables:

• halofit_version – (integer/string, one of: original, bird, peacock, takahashi, mead, halomodel, casarini, mead2015)
• HMCode_A_baryon – (float64) HMCode parameter A_baryon
• HMCode_eta_baryon – (float64) HMCode parameter eta_baryon

set_params(halofit_version='mead', HMCode_A_baryon=3.13, HMCode_eta_baryon=0.603)

Set the halofit model for non-linear corrections.

Parameters:

• halofit_version –

  One of

  • original: astro-ph/0207664
  • bird: arXiv:1109.4416
  • peacock: Peacock fit
  • takahashi: arXiv:1208.2701
  • mead: HMCode arXiv:1602.02154
  • halomodel: basic halomodel
  • casarini: PKequal arXiv:0810.0190, arXiv:1601.07230
  • mead2015: original 2015 version of HMCode arXiv:1505.07833
• HMCode_A_baryon – HMCode parameter A_baryon. Default 3.13.
• HMCode_eta_baryon – HMCode parameter eta_baryon. Default 0.603.

class camb.nonlinear.SecondOrderPK

Bases: camb.nonlinear.NonLinearModel

Third-order Newtonian perturbation theory results for the non-linear correction. Only intended for use at very high redshift (z>10) where corrections are perturbative, it will not give sensible results at low redshift.

See Appendix F of astro-ph/0702600 for equations and references.

Not intended for production use, it’s mainly to serve as an example alternative non-linear model implementation.