Projects per year
Abstract
We present a formalism for computing timedependent fluctuations in the cosmological photoionizing radiation background, extending background fluctuation models beyond the steadystate approximation. We apply this formalism to estimate fluctuations in the H I Ly α flux redshiftspace power spectrum and its spatial correlation function at redshifts 2 < z < 4, assuming the photoionization background is dominated by quasistellar objects (QSOs) and/or galaxies. We show that the shot noise in the power spectrum due to discrete sources is strongly suppressed relative to the steadystate value at low wavenumbers by a factor proportional to the lifetime of the sources, and that this suppression may be used to constrain QSO lifetimes. The total H I Ly α power spectrum including shot noise is affected at tens of per cent on short scales and by as much as an order of magnitude or more on scales exceeding the mean free path. The spatial correlation function is similarly found to be sensitive to the shot noise, although moderately insensitive to the effects of time dependence on the nonshotnoise contribution. Photoionization rate fluctuations substantially modify the shape of the baryonic acoustic oscillation peak in the correlation function, including a small increase in its position that must be accounted for to avoid biasing estimates of cosmological parameters based on the peak position. We briefly investigate solving the full frequencydependent equation, finding that it agrees with the frequencyindependent to better than per cent accuracy. Simple formulas are provided for the power spectrum of fluctuations in the photoionization rate that approximate the full computations.
Original language  English 

Pages (fromto)  47774997 
Number of pages  21 
Journal  Monthly Notices of the Royal Astronomical Society 
Volume  482 
Issue number  4 
Early online date  27 Oct 2018 
DOIs  
Publication status  Published  Feb 2019 
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Projects
 1 Finished

Astronomy and Astrophysics at Edinburgh
Taylor, A., Best, P., Biller, B., Dunlop, J., Ivison, R., Khochfar, S., McLure, R. & Meiksin, A.
1/04/18 → 31/03/21
Project: Research
Profiles

Avery Meiksin
 School of Physics and Astronomy  Personal Chair in Theoretical and Computational Physics
Person: Academic: Research Active