Is the low-l microwave background cosmic?

TL;DR

It is shown that the quadrupole plane and the three octopole planes are far more aligned than previously thought (99.9% C.L.) with the direction of the cosmological dipole and with the equinoxes.

Abstract

The large-angle (low-l) correlations of the Cosmic Microwave Background exhibit several statistically significant anomalies compared to the standard inflationary big-bang model, however no connection has hitherto been drawn between them. Here we show that the quadrupole and octopole are far more correlated (99.97% C.L.) than previously thought. The quadrupole plane and the three octopole planes are remarkably aligned. Three of these planes are orthogonal to the ecliptic at a level inconsistent with gaussian random statistically isotropic skies at 99.8% C.L., and the normals to these planes are aligned at 99.9% C.L. with the direction of the cosmological dipole and with the equinoxes. The remaining octopole plane is orthogonal to the supergalactic plane at >99.9% C.L. In a combined quadrupole-octopole map, the ecliptic plane narrowly threads between a hot spot and a cold spot over approximately 1/3 of the sky, and separates the three strongest extrema (in the south ecliptic hemisphere) from the three weakest extrema (in the north ecliptic hemisphere).

Figures (3)

• Figure 1: The normal vectors for $\ell=2$ (dark grey), and $\ell=3$ (black), as well as $\pm$ the dipole direction (light grey), and the equinoxes (open circles) plotted in sinusoidal projection. The Galactic center is the coordinate origin. Galactic longitude is positive on the left. Grid lines are separated by $30^\circ$. The long-dashed line is the ecliptic; the short-dashed line is the supergalactic plane. The clustering of the $\ell=3$ normal vectors is indicative of the "planarity of the octopole" angelica. (The clustering is clearer to the eye in the south hemisphere because of the projection.) Their closeness to the $\ell=2$ normal is indicative of the quadrupole-octopole correlation. Note how three normals are close to the dipole, the ecliptic and the equinoxes, while the fourth is on the supergalactic plane.
• Figure 2: Cosmic quadrupole plus octopole, $T^{\rm DS}_{2+3}$ (from Tegmark map). Coordinates are as in Fig. 1, background color is $0\mu$K. The ecliptic (dashed line) avoids all extrema.
• Figure 3: Left to right: Cosmic (Doppler-subtracted) quadrupole, octopole, and $T^{\rm DS}_{2+3}+T_4$ from the Tegmark map. The coordinate system and color scale are as in Fig. 2. The ecliptic (dashed line) is noticeably less correlated with these maps than with the quadrupole-octopole map of Fig. 2.