CMB with Quintessence: Analytic Approach and CMBFAST

Abstract

A particular kind of quintessence is considered, with equation of motion $p_Q/{\rho }_Q=-1$, corresponding to a cosmological term with time-dependence $\Lambda (t)=\Lambda (t_0)(R(t_0)/R(t){)}^P$ which we examine initially for $0\le P<3$. Energy conservation is imposed, as is consistency with big-bang nucleosynthesis, and the range of allowed $P$ is thereby much restricted to $0\le P<0.2$. The position of the first Doppler peak is computed analytically and the result combined with analysis of high-Z supernovae to find how values of ${\Omega }_m$ and ${\Omega }_{\Lambda }$ depend on $P$. Some comparison is made to the CMBFAST public code.

Comments: 13 pp LaTeX and 7 postscript figures