# nbodykit.cosmology.power.transfers¶

Classes

 CLASS(cosmo, redshift) The linear matter transfer function using the CLASS Boltzmann code. EisensteinHu(cosmo, redshift) The linear matter transfer function using the Eisenstein & Hu (1998) fitting formula with BAO wiggles. NoWiggleEisensteinHu(cosmo, redshift) Linear power spectrum using the Eisenstein & Hu (1998) fitting formula without BAO wiggles.
class nbodykit.cosmology.power.transfers.CLASS(cosmo, redshift)[source]

The linear matter transfer function using the CLASS Boltzmann code.

Parameters
• cosmo (Cosmology) – the cosmology instance

• redshift (float) – the redshift of the power spectrum

Methods

 Return the CLASS linear transfer function at redshift.
__call__(k)[source]

Return the CLASS linear transfer function at redshift. This computes the transfer function from the CLASS linear power spectrum using:

$T(k) = \left [ P_L(k) / k^n_s \right]^{1/2}.$

We normalize the transfer function $$T(k)$$ to unity as $$k \rightarrow 0$$ at $$z=0$$.

Parameters

k (float, array_like) – the wavenumbers in units of $$h \mathrm{Mpc}^{-1}$$

Returns

Tk – the transfer function evaluated at k, normalized to unity on large scales

Return type

float, array_like

class nbodykit.cosmology.power.transfers.EisensteinHu(cosmo, redshift)[source]

The linear matter transfer function using the Eisenstein & Hu (1998) fitting formula with BAO wiggles.

Parameters
• cosmo (Cosmology) – the cosmology instance

• redshift (float) – the redshift of the power spectrum

References

Eisenstein & Hu, “Baryonic Features in the Matter Transfer Function”, 1998

Methods

 Return the Eisenstein-Hu transfer function with BAO wiggles.
__call__(k)[source]

Return the Eisenstein-Hu transfer function with BAO wiggles.

This is normalized to unity as $$k \rightarrow 0$$ at $$z=0$$. The redshift scaling is provided by the Cosmology.scale_independent_growth_factor() function.

Parameters

k (float, array_like) – the wavenumbers in units of $$h \mathrm{Mpc}^{-1}$$

Returns

Tk – the transfer function evaluated at k, normalized to unity on large scales

Return type

float, array_like

class nbodykit.cosmology.power.transfers.NoWiggleEisensteinHu(cosmo, redshift)[source]

Linear power spectrum using the Eisenstein & Hu (1998) fitting formula without BAO wiggles.

Parameters
• cosmo (Cosmology) – the cosmology instance

• redshift (float) – the redshift of the power spectrum

References

Eisenstein & Hu, “Baryonic Features in the Matter Transfer Function”, 1998

Methods

 Return the Eisenstein-Hu transfer function without BAO wiggles.
__call__(k)[source]

Return the Eisenstein-Hu transfer function without BAO wiggles.

This is normalized to unity as $$k \rightarrow 0$$ at $$z=0$$. The redshift scaling is provided by the scale_independent_growth_factor() function.

Parameters

k (float, array_like) – the wavenumbers in units of $$h \mathrm{Mpc}^{-1}$$

Returns

Tk – the transfer function evaluated at k, normalized to unity on large scales

Return type

float, array_like