Evidence for orgin of CMB primary anisotropies

[zonde]

I wanted to ask if there are any tests that CMB primary anisotropies are ancient?
Or to put it differently can we exclude possibility that they are forming somewhere not far from Solar system say on some spherical horizon?

Just thought that black body spectrum is what you would expect from quantization of energy that is not associated with matter. So it's quite general effect of quantization and not something specific to Big-Bag model.

 

[marcus]

I'm not sure what you mean by "primary", or what you have in mind as a recent origin.

One "primary" anisotropy must surely be the dipole. Are you familiar with the standard explanation of that?

The size and direction of the dipole are roughly what one would expect from a knowledge of the speed and direction of the solar system as it orbits Galactic center, and an assumption that Milkyway galaxy is falling towards the concentration of mass ("great attractor") in the direction of Hydra-Centaurus in the southern hemisphere.

I wouldn't call it an iron-clad logical deduction, but it is a fairly plausible story explaining the dipole. It all fits together. And that would involve causes which are neither "not far from Solar system" nor directly related to the early universe. Our orbital speed and direction is determined on a galactic timescale and distance scale---it changes on a timescale on the order of a hundred million years. Independent measurements of it were made around 100 years ago, long before the CMB dipole was observed.

The other anisotropies are very very slight. On the order of a thousandth of a percent, as I recall. Some are consistent with other astrophysical observation (the integrated Sachs-Wolfe effect). There's a pretty tight case that we are looking at ancient light emitted about 380,000 years into expansion by matter that was then 41 million lightyears away and is now about 45 billion lightyears from us. We know what the speed of sound was in that hot medium, and the ripples are about the right size to go with that speed of sound. A lot of details fit together nicely.

 

[Chalnoth]

I wanted to ask if there are any tests that CMB primary anisotropies are ancient?
Or to put it differently can we exclude possibility that they are forming somewhere not far from Solar system say on some spherical horizon?

Because we see galaxy clusters in front of the CMB. The effect is known as the effect[/url].

 

[LithiumHelios]

Or you can see or own galaxy in most near radio images...

See:

http://arxiv.org/abs/1001.4555
http://arxiv.org/abs/1001.4538

http://lambda.gsfc.nasa.gov/product...ear/foreground/wmap_7yr_foreground_images.cfm

http://lambda.gsfc.nasa.gov/product...sic_results/wmap_7yr_basic_results_images.cfm

However also see: http://arxiv.org/abs/0909.2495 for a fairly neat paper suggesting that certain systematic effects may crop up if we fail to correctly account for these sorts of corrections to the primary anisotropies. May be more along the lines of what you were thinking?

Also there should be weak-lensing effects associated with the presence of matter/LSS/clusters/galaxies etc that should be detectable in the near future. Keep an eye out for the Planck release soon on the SZ catalogue!

"Just thought that black body spectrum is what you would expect from quantization of energy that is not associated with matter." - Also not quite sure what your trying to get at with this statement? For a quick background, the primordial plasma was, before recombination, a distribution of free protons, photons and electrons coupled through Thomson scattering etc such that the mean free path of the photons was extremely small. As Universe expands the temperature cools until the free electrons are able to combine with free protons (i.e. photons no longer dissociate the atoms that form; thermalied distribution ->blackbody) and the number density of free electrons drops significantly -> Photons now have mean free paths ~ size of observable universe and travel relatively unperturbed to us, the observers. The observed CMB Temperature anisotropies are generated by the gravitational redshift (in which density perturbations [initially seeded by quantum fluctuations during inflation] at the last scattering surface generate a varying potential along the surface) of photons that are emitted after recombination.

As mentioned above the CMB photons can be re-scattered to different energies (see SZ effects) causing a drop in the number of observed CMB (i.e. microwave) photons. Can also have other secondary effects that generate changes to the observed level of anisotropy (i.e. Rees-Sciama effects/ISW etc). So that's the quick idea of things...

You would also need some mechanism generating radio/microwave photons in a highly isotropic pattern around the solar system in sufficient quantities to reproduce the observed CMB...

 

[Chronos]

Well, LithiumHelios, you saved me a lot of work. Outstanding post.

 

[zonde]

Thanks for replies
I think I will find the answers in references that LithiumHelios provided.