CMB anisotropies and the ISW effect

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In summary, two papers published on arxiv today, one from India and the other from Spain, USA, and Italy, propose a solution to the CMB anisotropies observed by WMAP and Planck through the Integrated Sachs-Wolfe effect. Prior to these papers, possible explanations for the observed anisotropies included gigantic voids, topological defects, and quantum entanglement with a parallel universe. These explanations involved complex and unconventional physics.
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Two papers on arxiv today, http://arxiv.org/abs/1312.0025 and http://arxiv.org/abs/1312.0275, propose to resolve a large part of the CMB anisotropies suggested by WMAP and Planck based on the Integrated Sachs-Wolfe effect. The authorship appears independent, the former group is from India, and the latter from Spain, USA and Italy.
 
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Do you know what was thought to be the cause of the anisotropies prior to these papers?
 
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Possible explanations for the dipole modulation addressed by 1312.0275 have included gigantic voids, a topological defect remaining from a phase transition in the early universe, and quantum entanglement with a parallel universe before separation occurred during inflation. They invoked some rather ... exotic ... physics.
 
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What is CMB anisotropies and the ISW effect?

CMB anisotropies refer to the small fluctuations in temperature and polarization observed in the cosmic microwave background (CMB) radiation. These fluctuations provide important clues about the structure and evolution of the universe. The Integrated Sachs-Wolfe (ISW) effect is a phenomenon where CMB photons gain or lose energy as they pass through large-scale structures in the universe, such as clusters of galaxies.

What causes CMB anisotropies?

The CMB anisotropies are a result of density fluctuations in the early universe, which were amplified by inflation and later gravitational collapse. These fluctuations left imprints in the CMB radiation, which we can observe today.

How do we detect the ISW effect?

The ISW effect can be detected by comparing the temperature of the CMB radiation in different directions. If there is a large-scale structure along the line of sight, the CMB photons will gain or lose energy as they pass through it, leading to a temperature difference. This temperature difference can be measured using sensitive telescopes and is a signature of the ISW effect.

What can we learn from studying CMB anisotropies and the ISW effect?

Studying CMB anisotropies and the ISW effect allows us to probe the early universe and understand the formation and evolution of large-scale structures. It also helps us to test and refine our theories of cosmology, including inflation and dark energy.

Are there any ongoing or future experiments dedicated to studying CMB anisotropies and the ISW effect?

Yes, there are several ongoing and future experiments dedicated to studying CMB anisotropies and the ISW effect, such as the Planck satellite, the Atacama Cosmology Telescope, and the Simons Observatory. These experiments use advanced technology and techniques to map the CMB radiation with high precision and study the ISW effect in detail.

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