http://arxiv.org/abs/1812.01636
The late-time integrated Sachs-Wolfe (ISW) signal in the CMB temperature anisotropies is an important probe of dark energy when it can be detected by cross-correlation with large-scale structure surveys. Because of their huge volume, surveys in the radio are well-suited to ISW detection. We show that 21cm intensity mapping and radio continuum surveys with the SKA in Phase~1 promise a $\sim5\sigma$ detection, with a similar forecast for the precursor EMU survey. In SKA2, the 21cm galaxy redshift survey could deliver a $\sim6\sigma$ detection, which is probably the maximum achievable level. Our analysis includes the observational effects on the radio surveys of lensing magnification, Doppler and other relativistic corrections. These effects alter the shape of the measured ISW signal, especially at high redshift. The cross-correlation between lensing magnification and CMB temperature at high redshift is not a direct probe of dark energy and could bias the ISW reconstruction. We find that cross-correlation between different redshift bins compensates the shift due to adding the relativistic corrections in the ISW detection and improves the quality of the ISW reconstruction.
M. Ballardini and R. Maartens
Thu, 6 Dec 18
52/52
Comments: 11 pages, 5 figures, 4 tables
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