Suppressing CMB Quadrupole with a Bounce from Contracting Phase to Inflation

Abstract

Recent released WMAP data show a low value of quadrupole in the CMB temperature fluctuations, which confirms the early observations by COBE. In this paper, a scenario, in which a contracting phase is followed by an inflationary phase, is constructed. We calculate the perturbation spectrum and show that this scenario can provide a reasonable explanation for lower CMB anisotropies on large angular scales.

Figures (2)

• Figure 1: The power spectrum ${\cal P}_g$as a function of ${k\over {\cal H}_0}$. The x-axe is ${k\over {\cal H}_0}$, and the y-axe is $P_g /\left({{\cal H}_0\over 2\pi}\right)^2$.
• Figure 2: CMB anisotropy and two-point temperature correlation function for the scale invariant spectrum and the spectrum with a cutoff. Left: From left top to bottom, the lines stand for scale invariant spectrum, spectrum with a cutoff with ${\cal H}_0=2.1,3.1$ and $4.1\times 10^{-4}$ Mpc$^{-1}$. Other parameters are fixed at $h=0.73$, $\Omega_b h^2=0.023$, $\Omega_{cdm} h^2= 0.117$ and $\tau=0.2$. Right: From right top to bottom,the lines stand for scale invariant spectrum, spectrum with a cutoff with ${\cal H}_0=2.1,3.1$ and $4.1\times 10^{-4}$ Mpc$^{-1}$ and the WMAP released data.