Constraints on Fundamental Cosmological Parameters with Upcoming Redshifted 21 cm Observations

Constraints on cosmological parameters from upcoming measurements with theMileura Widefield Array-Low Frequency Demonstrator (MWA-LFD) of the redshifted21 cm power spectrum are forecast assuming a flat LCDM cosmology and that thereionization of neutral hydrogen in the intergalactic medium occurs below aredshift of z=8. We find that observations with the MWA-LFD cannot constrainthe underlying cosmology in this scenario. In principle, a similar experimentwith a 10-fold increase in collecting area could provide useful constraints onthe slope of the inflationary power spectrum, n_s, and the running of thespectral index, alpha_s, but these constraints are subject to the caveat thateven a small reionization contribution could be confused with the cosmologicalsignal. In addition to the redshifted 21 cm signal, we include two nuisancecomponents in our analysis related to the systematics and astrophysicalforegrounds present in low-frequency radio observations. These components arefound to be well separated from the signal and contribute little uncertainty(<30%) to the measured values of the cosmological model parameters.Comment: Replaced with version accepted by ApJ. 13 pages, including 4 figures and 5 table