## Abstract

Observations of the neutral hydrogen (H I) 21-cm signal hold the potential of allowing us to map out the cosmological large-scale structures (LSS) across the entire post-reionization era (z ≤ 6). Several experiments are planned to map the LSS over a large range of redshifts and angular scales, many of these targeting the Baryon Acoustic Oscillations. It is important to model the H I distribution in order to correctly predict the expected signal, and more so to correctly interpret the results after the signal is detected. In this paper we have carried out semi-numerical simulations to model the H I distribution and study the H I power spectrum P_{HI}(k,z) across the redshift range 1 ≤ z ≤ 6. We have modelled the H I bias as a complex quantity b~(k,z) whose modulus squared b^{2}(k,z) relates P_{HI}(k,z) to the matter power spectrum P(k,z), and whose real part b_{r}(k,z) quantifies the cross-correlation between the H I and the matter distribution. We study the z and k dependence of the bias, and present polynomial fits which can be used to predict the bias across 0 ≤ z ≤ 6 and 0.01 ≤ k ≤ 10 Mpc^{-1}. We also present results for the stochasticity r = b_{r}/b which is important for cross-correlation studies.

Original language | English |
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Pages (from-to) | 4310-4319 |

Number of pages | 10 |

Journal | Monthly Notices of the Royal Astronomical Society |

Volume | 460 |

Issue number | 4 |

DOIs | |

State | Published - 21 Aug 2016 |

Externally published | Yes |

## Keywords

- Cosmology: theory
- Diffuse radiation
- Large scale structure of Universe
- Methods: statistical

## ASJC Scopus subject areas

- Astronomy and Astrophysics
- Space and Planetary Science