2015/05/31 by Catherine A. Watkinson, Catherine A Watkinson, Jonathan R. Pritchard · 2 citations
Engineering · Physics and Astronomy · #Amplitude #Antenna Design and Optimization #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Brightness #Cosmic variance #Coupling (piping) #Galaxy #Kurtosis #Luminosity #Optics #Physics #Radio Astronomy Observations and Technology #Redshift #Reionization #Skewness #Statistics #astro-ph.CO
paper · pdf · doi:10.1093/mnras/stv2010
16 pages, 13 figure, 1 table. Accepted for publication in MNRAS
arxiv created 2015/09/03 · arxiv updated 2015/09/04 · openalex publication_date 2015/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
This paper considers the impact of Lyman α coupling and X-ray heating on the 21-cm brightness-temperature one-point statistics (as predicted by seminumerical simulations). The X-ray production efficiency is varied over four orders of magnitude and the hardness of the X-ray spectrum is varied from that predicted for high-mass X-ray binaries, to the softer spectrum expected from the hot interstellar medium. We find peaks in the redshift evolution of both the variance and skewness associated with the efficiency of X-ray production. The amplitude of the variance is also sensitive to the hardness of the X-ray spectral energy distribution. We find that the relative timing of the coupling and heating phases can be inferred from the redshift extent of a plateau that connects a peak in the variance's evolution associated with Lyman α coupling to the heating peak. Importantly, we find that late X-ray heating would seriously hamper our ability to constrain reionization with the variance. Late X-ray heating also qualitatively alters the evolution of the skewness, providing a clean way to constrain such models. If foregrounds can be removed, we find that LOFAR, MWA and PAPER could constrain reionization and late X-ray heating models with the variance. We find that HERA and SKA (phase 1) will be able to constrain both reionization and heating by measuring the variance using foreground-avoidance techniques. If foregrounds can be removed they will also be able to constrain the nature of Lyman α coupling.