Antisymmetric cross-correlation of line-intensity maps as a probe of reionization

TL;DR

This paper introduces a new antisymmetric estimator for line intensity map cross-correlations to better probe the Epoch of Reionization, potentially improving parameter constraints by including previously neglected signals.

Contribution

It proposes the antisymmetric component of the cross-correlation as a novel estimator, enhancing the analysis of reionization signals in line intensity maps.

Findings

Including antisymmetric signals improves reionization parameter constraints.

The antisymmetric-to-symmetric ratio helps break degeneracies in astrophysical models.

Results show significant information gain in standard reionization scenarios.

Abstract

We present a new estimator for the cross-correlation signal between line intensity maps to probe the Epoch of Reionization. The proposed estimator is the hitherto neglected antisymmetric component of the cross-correlation, under the exchange of line-of-sight positions. We consider the cross-correlation between HI and CO fluctuations, and forecast the improvement in precision on reionization parameters when the antisymmetric contribution is accounted for. As a way to break the degeneracy between astrophysics and cosmology in the intensity mapping power spectrum, we study the ratio between the antisymmetric and symmetric components. While our results depend on the highly uncertain astrophysical modelling, we show that in most standard scenarios including the antisymmetric contribution as a complementary probe can lead to a significant gain in information.