## [0912.1460] A dipole anisotropy of galaxy distribution: Does the CMB rest-frame exist in the local universe?

 Authors: Yousuke Itoh, Kazuhiro Yahata, Masahiro Takada Abstract: The peculiar motion of the Earth causes a dipole anisotropy modulation in the distant galaxy distribution due to the aberration effect. However, the amplitude and angular direction of the effect is not necessarily the same as those of the cosmic microwave background (CMB) dipole anisotropy due to the growth of cosmic structures. In other words exploring the aberration effect may give us a clue to the horizon-scale physics perhaps related to the cosmic acceleration. In this paper we develop a method to explore the dipole angular modulation from the pixelized galaxy data on the sky properly taking into account the covariances due to the shot noise and the intrinsic galaxy clustering contamination as well as the partial sky coverage. We applied the method to the galaxy catalogs constructed from the Sloan Digital Sky Survey (SDSS) Data Release 6 data. After constructing the four galaxy catalogs that are different in the ranges of magnitudes and photometric redshifts, we found that the two samples of fainter magnitudes indicate a non-zero dipole anisotropy with amplitudes greater than that of the CMB dipole by a factor 10 and in the angular direction consistent with the CMB direction, although the dipole signal is weaker for the other two samples and is found sensitive to an inclusion of the Southern Galactic Hemisphere region. The indicated bulk-flow amplitude is also not inconsistent with the result implied from a stacked analysis of the kinetic Sunyaev-Zel'dovich effect of X-ray luminous clusters in Kashlinsky et al. (2008,2009). Finally we argue that an almost full-sky galaxy survey such as LSST may allow for a significant detection of the aberration effect of the CMB dipole having the precision of constraining the angular direction to $\sim 20$ degrees in radius. [PDF]  [PS]  [BibTex]  [Bookmark]

Discussion related to specific recent arXiv papers
Anze Slosar
Posts: 183
Joined: September 24 2004
Affiliation: Brookhaven National Laboratory
Contact:

### [0912.1460] A dipole anisotropy of galaxy distribution: Doe

This is something I always dreamt of doing... It is quite neat and the "detection" they have points at how difficult is to do this in practice... :)