Cosmic Radiation: The Dawn Of New Physics Or Statistical Slip-Up?

Geraint Lewis (yes…)

Recent observations suggest that there is something not quite right with our view of our universe – that something is skewing our view of the oldest radiation arriving at our telescopes.

What’s causing this skewing? Is it new fundamental physics, or something as bizarre as a collision with another universe?

While these are extremely exciting, a study published today in the Journal of Cosmology and Astroparticle Physics suggests the solution is much more mundane – it’s the way the data was originally analysed that produced apparently significant anomalies.

&c &c &c

Original article:

Planck CMB anomalies: astrophysical and cosmological secondary effects and the curse of masking

Large-scale anomalies have been reported in CMB data with both WMAP and Planck data. These could be due to foreground residuals and or systematic effects, though their confirmation with Planck data suggests they are not due to a problem in the WMAP or Planck pipelines. If these anomalies are in fact primordial, then understanding their origin is fundamental to either validate the standard model of cosmology or to explore new physics. We investigate three other possible issues: 1) the trade-off between minimising systematics due to foreground contamination (with a conservative mask) and minimising systematics due to masking, 2) astrophysical secondary effects (the kinetic Doppler quadrupole and kinetic Sunyaev-Zel’dovich effect), and 3) secondary cosmological signals (the integrated Sachs-Wolfe effect). We address the masking issue by considering new procedures that use both WMAP and Planck to produce higher quality full-sky maps using the sparsity methodology (LGMCA maps). We show the impact of masking is dominant over that of residual foregrounds, and the LGMCA full-sky maps can be used without further processing to study anomalies. We consider four official Planck PR1 and two LGMCA CMB maps. Analysis of the observed CMB maps shows that only the low quadrupole and quadrupole-octopole alignment seem significant, but that the planar octopole, Axis of Evil, mirror parity and cold spot are not significant in nearly all maps considered. After subtraction of astrophysical and cosmological secondary effects, only the low quadrupole may still be considered anomalous, meaning the significance of only one anomaly is affected by secondary effect subtraction out of six anomalies considered.

Pigeon poo

Skeptic Pete said:

Pigeon poo

A really really big pigeon

Skeptic Pete said:

Pigeon poo

foreground residuals

>suggests the solution is much more mundane

That was one of TDO’s useful roles in SSSF – reassuring us “there’s nothing to see here” when some new-fangled weirdy idea was being floated.

OCDC said:

Cosmic Radiation: The Dawn Of New Physics Or Statistical Slip-Up?

Geraint Lewis (yes…)

I prefer not to get my science news from an astrologer.

sibeen said:

OCDC said:

Cosmic Radiation: The Dawn Of New Physics Or Statistical Slip-Up?

Geraint Lewis (yes…)

I prefer not to get my science news from an astrologer.

But he’s Our Astrologer!

> Analysis of the observed CMB maps shows that only the low quadrupole and quadrupole-octopole alignment seem significant, but that the planar octopole, Axis of Evil, mirror parity and cold spot are not significant in nearly all maps considered. After subtraction of astrophysical and cosmological secondary effects, only the low quadrupole may still be considered anomalous, meaning the significance of only one anomaly is affected by secondary effect subtraction out of six anomalies considered.

Good. I had long since discounted any special significance of the “cold spot” and “quadrupole-octopole alignment”. Both could easily be just statistical outliers. The “low quadrupole” may or may not have a cosmological significance, because different cosmological models predict different strengths of the quadrupole.