The plots on this page show estimates for errors on the 21cm power spectrum measured by LOFAR. The datacubes use the foreground simulations of Jelić et al. (2008) and the noise levels from the same paper (52mK for a 1MHz bandwidth at 150MHz for one 'year' [300 hours] of observation with one synthesized beam in one observational window; here we use 0.5MHz channels so the noise on each individual map is √2 times higher than this). The cosmological signal comes from the f250C simulation. All the power spectra shown are for maps convolved with the instrumental response. For these datacubes we model the uv coverage as being the same at all redshifts. Foreground subtraction uses Wp smoothing in the image cubes with λ=0.5. The original datacubes have 256×256×170 points, but these are binned up to 64×64×170 before foreground subtraction and power spectrum estimation. The error estimates come simply from estimating the variance of the variance in the residual cubes. The noise power spectrum is assumed to be known. All the power spectra are measured in slices of the datacube encompassing 16 frequency bins, since this gives a depth comparable to the size of our current cosmological signal simulation and prevents there having been too much evolution. For the 3D power spectrum this simply means measuring the power spectrum in this volume. For the 1D power spectra along the line of sight and the 2D angular power spectrum, we estimate the power spectrum in each line of sight or each image and then average all the power spectra in the slice to give the final estimate. All the power spectra are 'dimensionless' power spectra (not really dimensionless, since they're measured in Kelvin rather than using the dimensionless quantity δ used in cosmology, but they do give the variance per log wavenumber as usual).
If you want to see power spectra for different redshifts or
redshift ranges, or plots in different formats, that would be
straightforward for me to do. If the fitting has to be redone
(different binning, noise level or observation time) that will take
longer. This page should be updated as the simulations, extraction
procedures and error estimates are refined.
| Low redshift | Mid redshift | High redshift | |
|---|---|---|---|
| 1 beam, 1 year, 1 window | TIFF | TIFF | TIFF |
| 4 beams, 1 year, 1 window | TIFF | TIFF | TIFF |
| 4 beams, 4 years, 1 window | TIFF | TIFF | TIFF |
| 1 beam, 1 year, 5 windows | TIFF | TIFF | TIFF |
| 4 beams, 1 year, 5 windows | TIFF | TIFF | TIFF |
| 4 beams, 4 years, 5 windows | TIFF | TIFF | TIFF |
| Low redshift | Mid redshift | High redshift | |
|---|---|---|---|
| 1 beam, 1 year, 1 window | TIFF | TIFF | TIFF |
| 4 beams, 1 year, 1 window | TIFF | TIFF | TIFF |
| 4 beams, 4 years, 1 window | TIFF | TIFF | TIFF |
| 1 beam, 1 year, 5 windows | TIFF | TIFF | TIFF |
| 4 beams, 1 year, 5 windows | TIFF | TIFF | TIFF |
| 4 beams, 4 years, 5 windows | TIFF | TIFF | TIFF |
| Low redshift | Mid redshift | High redshift | |
|---|---|---|---|
| 1 beam, 1 year, 1 window | TIFF | TIFF | TIFF |
| 4 beams, 1 year, 1 window | TIFF | TIFF | TIFF |
| 4 beams, 4 years, 1 window | TIFF | TIFF | TIFF |
| 1 beam, 1 year, 5 windows | TIFF | TIFF | TIFF |
| 4 beams, 1 year, 5 windows | TIFF | TIFF | TIFF |
| 4 beams, 4 years, 5 windows | TIFF | TIFF | TIFF |