http://arxiv.org/abs/1812.11150
The observed hemispherical asymmetry in cosmic microwave background radiation can be explained by long mode modulation. In this work we study the prospect of the detection of this effect in $21cm$ brightness temperature fluctuations angular power spectrum. For this task we study the effect of the neutral Hydrogen distribution on the angular power spectrum. This is done by formulating the bias parameter of ionized fraction to the underlying matter distribution. We also discuss the possibility that the long mode modulation is companied with a primordial non-Gaussianity of local type. In this case we obtain the angular power spectrum with two effects of primordial non-Gaussianity and long mode modulation. Finally, we show that the primordial non-Gaussianity enhances the modulated power of $21cm$ via the non-Gaussian scale dependent bias. Accordingly the future square kilometer array like observation of $21cm$ cosmology are capable of detection of large scale anomalies of initial condition of early Universe.
S. Khosravi, A. Ghazizadeh and S. Baghram
Mon, 31 Dec 18
44/57
Comments: 9 pages, 7 figures
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