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The cross-power spectrum between 21 cm emission and galaxies in hierarchical galaxy formation models.

Park, J. and Kim, H.-S. and Wyithe, J.S.B. and Lacey, Cedric G. (2014) 'The cross-power spectrum between 21 cm emission and galaxies in hierarchical galaxy formation models.', Monthly notices of the Royal Astronomical Society., 438 (3). pp. 2474-2482.


The correlation between 21 cm fluctuations and galaxies is sensitive to the astrophysical properties of the galaxies that drove reionization. Thus, detailed measurements of the cross-power spectrum and its evolution could provide a powerful measurement of both the properties of early galaxies and the process of reionization. In this paper, we study the evolution of the cross-power spectrum between 21 cm emission and galaxies using a model which combines the hierarchical galaxy formation model GALFORM implemented within the Millennium-II dark matter simulation, with a semi-numerical scheme to describe the resulting ionization structure. We find that inclusion of different feedback processes changes the cross-power spectrum shape and amplitude. In particular, the feature in the cross-power spectrum corresponding to the size of ionized regions is significantly affected by supernovae feedback. We calculate predicted observational uncertainties of the cross-correlation coefficient based on specifications of the Murchison Widefield Array (MWA) combined with galaxy surveys of varying area and depth. We find that the cross-power spectrum could be detected over several square degrees of galaxy survey with galaxy redshift errors σz ≲ 0.1.

Item Type:Article
Keywords:Galaxies: high-redshift, Cosmology: Theory, Dark ages, Reionization, First stars, Diffuse, Radiation.
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Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2014 The Authors Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.
Date accepted:No date available
Date deposited:03 July 2014
Date of first online publication:March 2014
Date first made open access:No date available

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