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[astro-ph/0607160] Ellipticity in Cosmic Microwave Background as a Tracer of Large-Scale Universe
 
Authors:V.G.Gurzadyan, C.L.Bianco, A.L.Kashin, H.Kuloghlian, G.Yegorian
Abstract:Wilkinson Microwave Anisotropy Probe (WMAP) 3-year data confirm the ellipticity of anisotropies of Cosmic Microwave Background (CMB) maps, found previously for Boomerang and WMAP 1-year high sensitivity maps. The low noise level of the WMAP latter data enable also to show that, the ellipticity is a property not described by the conventional cosmological model fitting the power spectrum of CMB. As a large scale anomaly, the ellipticity characteristics are consistent with the effect of geodesics mixing occurring in hyperbolic Universe. Its relation to other large scale effects, i.e. to suppressed low multipoles, as well as to dark energy if the latter is due to vacuum fluctuations, is then an arising issue.
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Syksy Rasanen



Joined: 02 Mar 2005
Posts: 128
Affiliation: University of Helsinki

PostPosted: January 29 2008  Reply with quote

The paper claims that the observed CMB ellipticity is very discrepant with the LCDM prediction.

At a quick glance, I don't quite understand what is going on. This ellipticity would mean that the CMB is not a Gaussian field, no? Is the analysis reliable?

An earlier paper on this was brought up in http://cosmocoffee.info/viewtopic.php?t=195 .
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Tarun Souradeep



Joined: 24 Oct 2004
Posts: 7
Affiliation: IUCAA

PostPosted: January 31 2008  Reply with quote

Elliptical spots does not necessarily imply non-Gaussianity !!
One can have very well have a Gaussian field that is not statistically isotropic (SI). The statistics is still completely represented by the two point correlation alone

The correlation function of temperature in two directions is not simply a function of the angular separation between n & n' : \langle\Delta T(n) \Delta T(n')\rangle \equiv C(n,n') \not\equiv C(n\cdot n').
In particular, hot/contours spots will not have circularly symmetric contours – elliptical contours is a simple special
case of that.


In harmonic space, SI condition implies the matrix \langle a_{lm} a_{l'm'} \rangle= C_l \delta_{ll'} \delta_{mm'} is diagonal in (l,m) space. Violation of SI
implies non-zero `off diagonal terms'

For discussion of non stat. iso. CMB
Please see (among many others referred in these papers)
Astrophys.J. 597 (2003) L5-L8
arXiv:astro-ph/0501001

(Should clarify I am not supporting that the observed ellipticity is correct. We never found any significant SI
violation in WMAP maps)
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