标题： PSCz偶极子再审视 显示英文标题

标题： The PSCz Dipole Revisited

摘要： 我们重新审视由红外天文卫星（IRAS）星系分布的点源目录红移巡天（PSCz）对本星系群产生的引力加速度（偶极子）。我们通过利用星系表面密度场的球谐展开至八极子阶数，处理了受尘埃影响的低银纬区域。我们发现有强烈迹象表明，本星系群运动可能来自深度达$\sim 185$ $h^{-1}$ Mpc 的区域，甚至可能来自$\sim 210$ $h^{-1}$ Mpc 的区域，这与Kocevski & Ebeling最近对全天X射线团巡天的分析结果一致。与之前的PSCz偶极子分析相比，变化之处在于：(a) 大尺度偶极子贡献和(b) 由于本地体积（$\mincir 4 h^{-1}$Mpc）的重要贡献而使整体偶极子振幅增加，我们现在考虑了这一点。这导致了$\beta (\equiv \Omega_{\rm m}^{0.6}/b)$参数值降低，我们在真实空间中发现其值为$\beta_{\rm IRAS} \simeq 0.49$。 因此，对于一致宇宙学模型 ($\Omega_{\rm m}=1-\Omega_{\Lambda}=0.3$)，IRAS星系的偏差因子是$b_{\rm IRAS}\simeq 1$，这意味着IRAS星系是潜在物质分布的良好示踪。 显示英文摘要

摘要： We re-examine the gravitational acceleration (dipole) induced on the Local Group of galaxies by the Infrared Astronomical Satellite (IRAS) galaxy distribution of the Point Source Catalogue redshift survey (PSCz). We treat the cirrus-affected low galactic latitudes by utilizing a spherical harmonic expansion of the galaxy surface density field up to the octapole order. We find strong indications for significant contributions to the Local Group motion from depths up to $\sim 185$ $h^{-1}$ Mpc and possible contribution even from $\sim 210$ $h^{-1}$ Mpc, in agreement with the recent analysis of Kocevski & Ebeling of a whole sky X-ray cluster survey.What changes with respect to the previous PSCz dipole analyses is: (a) the large-scale dipole contributions and (b) an increase of the overall dipole amplitude due to the important contribution of the local volume ($\mincir 4 h^{-1}$Mpc), which we now take into account. This results in a lower value of the $\beta (\equiv \Omega_{\rm m}^{0.6}/b)$ parameter, which we find to be $\beta_{\rm IRAS} \simeq 0.49$ in real space. Therefore, for the concordance cosmological model ($\Omega_{\rm m}=1-\Omega_{\Lambda}=0.3$) the IRAS galaxies bias factor is $b_{\rm IRAS}\simeq 1$ which means that IRAS galaxies are good traces of the underlying matter distribution.