## [astro-ph/0510137] Did WMAP see Moving Local Structures?

 Authors: Asantha Cooray, Naoki Seto Abstract: The divergence of the momentum density field of the large scale structure generates a secondary anisotropy contribution to the Cosmic Microwave Background (CMB). While the effect is best described as a non-linear extension to the well-known integrated Sachs-Wolfe effect, due to mathematical coincidences, the anisotropy contribution is also described as the lensing of the dipole seen in the rest-frame of a moving mass. Given the closeness, there is a remote possibility that local concentrations of mass in the form of the Great Attractor and the Shapley concentration generate large angular scale fluctuations in CMB and could potentially be responsible, at least partly, for some of the low-multipole anomalies in WMAP data. While the local anisotropy contribution peaks at low multipoles, for reasonable models of the mass and velocity distributions associated with local super structures we find that the amplitude of temperature anisotropies is at most at a level of 10$^{-2}$ $\mu$K and is substantially smaller than primordial fluctuations. It is extremely unlikely that the momentum density of local mass concentrations is responsible for any of the large angular scale anomalies in WMAP data. [PDF]  [PS]  [BibTex]  [Bookmark]

Discussion related to specific recent arXiv papers
Garth Antony Barber
Posts: 59
Joined: July 19 2005
Affiliation: Published independent

### [astro-ph/0510137] Did WMAP see Moving Local Structures?

How do we reconcile this paper with Chris Vale's paper astro-ph/0509039, "Local Pancake Defeats Axis of Evil" ?

Garth

Kate Land
Posts: 29
Joined: September 27 2004
Affiliation: Oxford University
Contact:

### [astro-ph/0510137] Did WMAP see Moving Local Structures?

I think it was generally decided that Vale gave the Great Attractor an unreasonable velocity (i.e. one similar to ours), and so his conclusions were unrealistic. The GA does not have the same rest frame as us and thus does not see the same dipole.

It looks like these guys properly take into account the different frames involved, and use realistic estimates of the velocities of various mass concentrations (GA, Shapley).

Chris Vale
Posts: 5
Joined: September 06 2005
Affiliation: Fermilab

### [astro-ph/0510137] Did WMAP see Moving Local Structures?

The velocity of the GA turns out to be a red herring, as I say in version 2 which will be on astro-ph on Monday; see my post Pancake forum for a brief discussion of why Asantha and I get very different answers.[/quote]