ﻻ يوجد ملخص باللغة العربية
It has recently been suggested that the power spectrum of redshifted 21cm fluctuations could be used to measure the scale of baryonic acoustic oscillations (BAOs) during the reionisation era. The resulting measurements are potentially as precise as those offered by the next generation of galaxy redshift surveys at lower redshift. However unlike galaxy redshift surveys, which in the linear regime are subject to a scale independent galaxy bias, the growth of ionised regions during reionisation is thought to introduce a strongly scale dependent relationship between the 21cm and mass power spectra. We use a semi-numerical model for reionisation to assess the impact of ionised regions on the precision and accuracy with which the BAO scale could be measured using redshifted 21cm observations. For a model in which reionisation is completed at z~6, we find that the constraints on the BAO scale are not systematically biased at z > 6.5. In this scenario, and assuming the sensitivity attainable with a low-frequency array comprising 10 times the collecting area of the Murchison Widefield Array, the BAO scale could be measured to within 1.5 per cent in the range 6.5 < z < 7.5.
We investigate the impact of neutral hydrogen (HI) in galaxies on the statistics of 21-cm fluctuations using analytic and semi-numerical modelling. Following the reionisation of hydrogen the HI content of the Universe is dominated by damped absorptio
We assess the effect of a population of high-redshift quasars on the 21-cm power spectrum during the epoch of reionisation. Our approach is to implement a semi-numerical scheme to calculate the three-dimensional structure of ionised regions surroundi
We incorporate a contribution to reionization from X-rays within analytic and semi-numerical simulations of the 21-cm signal arising from neutral hydrogen during the epoch of reionization. We explore the impact that X-ray ionizations have on the powe
The cosmic microwave background (CMB) polarisation and the 21 cm line fluctuations are powerful probes of cosmological reionisation. We study how the cross-correlation between the CMB polarisation (E-modes) and the 21 cm line fluctuations can be used
Using the 21 cm line, observed all-sky and across the redshift range from 0 to 5, the large scale structure of the Universe can be mapped in three dimensions. This can be accomplished by studying specific intensity with resolution ~ 10 Mpc, rather th