I am trying to adapt CAMB to some more exotic model of neutrinos. The particles in my model start different from radiation behaviour (p [tex]\neq[/tex] 1/3*[tex]\rho[/tex]).
I guess this information should be replaced in the (modules.f90) subroutine Nu_background(am,rhonu,pnu)
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if (am <= am_minp) then
rhonu=1._dl + const2*am**2
pnu=(2-rhonu)/3._dl
return
else if (am >= am_maxp) then
rhonu = 3/(2*const)*(zeta3*am + (15*zeta5)/2/am)
pnu = 900._dl/120._dl/const*(zeta5-63._dl/4*Zeta7/am**2)/am
return
end if
d=log(am/am_min)/dlnam+1._dl
i=int(d)
d=d-i
! Cubic spline interpolation.
rhonu=r1(i)+d*(dr1(i)+d*(3._dl*(r1(i+1)-r1(i))-2._dl*dr1(i) &
-dr1(i+1)+d*(dr1(i)+dr1(i+1)+2._dl*(r1(i)-r1(i+1)))))
pnu=p1(i)+d*(dp1(i)+d*(3._dl*(p1(i+1)-p1(i))-2._dl*dp1(i) &
-dp1(i+1)+d*(dp1(i)+dp1(i+1)+2._dl*(p1(i)-p1(i+1)))))
rhonu=exp(rhonu)
pnu=exp(pnu)
+ I tried to erase the first two posiblities and go direct to the cubic spline
interpolation but the output is ill. Why is not possible to assume directly the third case (which I understand corresponds to nonrelativistic neutrinos)?
+ I find that the key point is to understand the physical (or any) meaning of the parameters
am_minp=1.1*am_min=1.1*0.01=0.011
am_maxp=0.9*am_max=0.9*600 =540
I read that they are the smallest and greatest values of a*m_nu to integrate the distribution function rather than using series, but this does not completely help. How will this parameters change the outputs? Or what are the rules to evaluate them?
In other words, my goal here, is to set [tex]\rho[/tex] in the background as something which evolves different from purely relativistic particles.
I want to thank your attention and advice.
Ivan R.