We investigate the prospects of measuring the cosmic magnification effect by cross-correlating neutral hydrogen intensity mapping (HI IM) maps with background optical galaxies. We forecast the signal-to-noise ratio for HI IM data from SKA1-MID and HIRAX, combined with LSST photometric galaxy samples. We find that, thanks to their different resolutions, SKA1-MID and HIRAX are highly complementary in such an analysis. We predict that SKA1-MID can achieve a detection with a signal-to-noise ratio of ∼15 on a multipole range of ℓ≲200, while HIRAX can reach a signal-to-noise ratio of ∼50 on 200<ℓ<2000. We conclude that measurements of the cosmic magnification signal will be possible on a wide redshift range with foreground HI intensity maps up to z≲2, while optimal results are obtained when 0.6≲z≲1.3. Finally, we perform a signal to noise analysis that shows how these measurements can constrain the HI parameters across a wide redshift range.
@article{arxiv.1907.00755,
title = {Prospects for cosmic magnification measurements using HI intensity mapping},
author = {Amadeus Witzemann and Alkistis Pourtsidou and Mario G. Santos},
journal= {arXiv preprint arXiv:1907.00755},
year = {2020}
}