Testing isotropy in the local Universe
Testing isotropy in the local Universe
复制标题
DOI：
10.1088/1475-7516/2014/10/070
复制
发表时间：
2014-05
影响因子：
6.4
通讯作者：
S. Appleby;A. Shafieloo
中科院分区：
文献类型：
--
作者：
S. Appleby;A. Shafieloo
我们使用 2MASS 扩展源目录测试星系局部分布的各向同性。通过将全天调查分解为不同的斑块并结合使用光度和光谱红移数据，我们使用参数和非参数方法来获得每个斑块中的光度函数的形状。我们使用光度函数的形状来测试底层星系分布的统计各向同性。参数估计器显示了南北银河平面半球不对称的一些证据。然而，非参数估计量没有表现出显着的各向异性，星系分布与所考虑的所有区域中各向同性的假设一致。参数不对称归因于函数形式与基础数据的拟合相对较差。当使用非参数估计器时，我们确实找到了光度函数形状的偶极子，在银河坐标 (b,l)=(30̂,315̂) 处与各向同性的最大偏差。然而，我们不能认为这一观察结果具有很强的统计意义。
We test the isotropy of the local distribution of galaxies using the 2MASS extended source catalogue. By decomposing the full sky survey into distinct patches and using a combination of photometric and spectroscopic redshift data, we use both parametric and non-parametric methods to obtain the shape of the luminosity function in each patch. We use the shape of the luminosity function to test the statistical isotropy of the underlying galaxy distribution. The parametric estimator shows some evidence of a hemispherical asymmetry in the north/south Galactic plane. However the non-parametric estimator exhibits no significant anisotropy, with the galaxy distribution being consistent with the assumption of isotropy in all regions considered. The parametric asymmetry is attributed to the relatively poor fit of the functional form to the underlying data. When using the non-parametric estimator, we do find a dipole in the shape of the luminosity function, with maximal deviation from isotropy at galactic coordinate (b,l)=(30̂,315̂). However we can ascribe no strong statistical significance to this observation.