Equations in Quint module in quintessence equations file for CAMB
Posted: January 30 2020
Hi all,
I am trying to modify the equation file for quintessence for CAMB provided at https://camb.info/equations_quint.f90.
In subroutine EvolveBackground, the energy density of the scalar field is defined as
which is consistent with the standard definition [math] (eq. 6.5 in Theory of cosmological perturbations ) upto a overall factor of [math] where prime denotes the derivative with respect to the conformal time.
But later in the file in function Quint_GetOmegaFromInitial, it is given that
which is supposed to produce the value of [math], which should be [math] multiplied by an overall factor.
But considering the definition this doesn't seem to be consistent with the definition since
is equivalent to [math] which cannot be same as the definition of $\rho_{\phi}$ or $\Omega_{\phi}$ irrespective of any overall factor.
I am not sure if it is an error in the code, or if I am missing something.
Best
Joseph
I am trying to modify the equation file for quintessence for CAMB provided at https://camb.info/equations_quint.f90.
In subroutine EvolveBackground, the energy density of the scalar field is defined as
Code: Select all
tmp=a2*(0.5d0*phidot**2 + a2*Vofphi(phi,0))
But later in the file in function Quint_GetOmegaFromInitial, it is given that
Code: Select all
Quint_GetOmegaFromInitial=(0.5d0*y(2)**2 + Vofphi(y(1),0))/(3*adot**2)
But considering the definition
Code: Select all
y(2)=phidot*astart**2
Code: Select all
tmp=a2*(0.5d0*phidot**2 + a2*Vofphi(phi,0))
Code: Select all
(0.5d0*y(2)**2 + Vofphi(y(1),0))
I am not sure if it is an error in the code, or if I am missing something.
Best
Joseph