What does the TE CMB spectrum reveal?

[Rene Kail]

Does the polarization spectrum TE measured by the Planck and WMAP satellites show evidence for superhorizon fluctuations at low multipoles and are these evidence for pre-bigbang inflation?

 

[Hyperfine]

Does the polarization spectrum TE measured by the Planck and WMAP satellites show evidence for superhorizon fluctuations at low multipoles and are these evidence for pre-bigbang inflation?

According to Will Kinney, yes. Kinney is a professor of Physics at SUNY Buffalo.

In chapter 6 of his recent book (see below) he presents a figure of the TE cross-correlation power spectrum showing an anti-correlation at low multipole moments assigned as superhorizon modes. Unfortunately, no reference to the literature is given.

The actual power spectrum is from the Planck collaboration. I checked that, although I fail to recall from which of their many papers.

Will Kinney, An Infinity of Worlds: Cosmic Inflation and the Beginning of the Universe, The MIT Press, 2022.

 

[Hyperfine]

To elaborate the comments made in Post #2. The TE cross-correlation power spectrum (courtesy of NASA/LAMBDA Archive Team) from the Planck mission is illustrated below:

It is the negative going peak in the power spectrum near $\ell=100$ that Kinney attributes to evidence consistent with superhorizon modes and thus with inflation.

By far the most powerful general test of inflation is the presence of superhorizon perturbations. This is a prediction that is, at least in the case of an expanding universe, unique to inflation ... , and does not depend on any particular model for inflation. No purely causal theory in an expanding universe can produce superhorizon perturbations.