http://arxiv.org/abs/2009.02766
The antisymmetric part of two-point cross-correlation between intensity maps of the HI 21 cm line and the CO 2.61 mm line has emerged as a new probe of cosmic reionization. In this Letter we demonstrate that the slope of the dipole of HI-CO cross-power spectrum at large scales is linear to the rate of change of global neutral fraction of hydrogen in a model-independent way, until the slope levels out near the end of reionization. The HI-CO dipole, therefore, can be a smoking-gun probe for the speed of reionization, or “standard speedometer”. Observations of this new signal will unveil the global reionization history from the midpoint to near the completion of reionization.
M. Zhou, Y. Mao and J. Tan
Tue, 8 Sep 20
-1459/68
Comments: 4 pages, 5 figures, 1 table
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