Kinematic Quadrupole Correction of CBR Anisotropies and Local Collapse

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Session 71 -- Galaxy and CBR Distribution
Display presentation, Friday, January 14, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[71.16] Kinematic Quadrupole Correction of CBR Anisotropies and Local Collapse

Li-Zhi Fang (Steward Obs., Univ. of Aeriz), Xiang-Ping Wu (DAEC, Obs. de Paris-Meudon)

In order to find the cosmic amplitude of the CBR quadrupole at the surface of last scattering, the kinematic quadrupole correction of the CBR anisotropies, $(\Delta {\sf T}/{\sf T})_q=(\Delta {\sf T}/{\sf T})_d^2/2$, is usually applied to remove the contamination of the quadrupole produced by local density inhomogeneities. Using an exact solution of the CBR anisotropy produced by a local collapse described by a spherical over-dense region embedded in a flat universe, we have found that the quadrupole of local collapse origin cannot always be approximately described by the kinematic quadrupole. Our numerical result shows that the difference between the kinematic and local quadrupoles depends on the size and matter density in the peculiar field, and the position of the observer. For a given dipole, the local quadrupole can be different from the kinematic quadrupole by a factor as large as 3. Therefore, the kinematic quadrupole correction remains an uncertain factor in the determination of the amplitude of a cosmic quadrupole. Nevertheless, a preliminary analysis shows that this uncertainty might not dramatically change the cosmological origin of the COBE-DMR's quadrupole, unless a huge peculiar gravitational field is assumed.

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