Robust Intensity Mapping Analysis against Foregrounds for the Epoch of Reionization

Abstract

Intensity mapping of the HI 21 cm line and the CO 2.61 mm line from the epoch of reionization has emerged as powerful, complementary, probes of the high-redshift Universe. However, both maps and their cross-correlation are dominated by foregrounds. We propose a new analysis by which the signal is unbiased by foregrounds, i.e. it can be measured without foreground mitigation. We construct the antisymmetric part of the HI-CO cross-correlation, arising because the statistical fluctuations of two fields have different evolution in time. We show that the sign of this new signal can distinguish model-independently whether inside-out reionization happens during some interval of time.

arXiv:2009.02765 (now withdrawn) and arXiv:2009.02766 are now merged into a long paper that has now been accepted for publication at the ApJ. This published version is updated in arXiv:2009.02766