Antisymmetric galaxy cross-correlations in and beyond ΛCDM

Many different techniques to analyze galaxy clustering data and obtain cosmological constraints have been proposed, tested, and used. Given the large amount of data that will be available soon, it is worth investigating new observables and ways to extract information from such datasets. In this paper, we focus on antisymmetric correlations that arise in the cross-correlation of different galaxy populations when the small-scale power spectrum is modulated by a long-wavelength field. In Lambda cold dark matter this happens because of nonlinear clustering of sources that trace the underlying matter distribution in different ways. Beyond the standard model, this observable is sourced naturally in various new physics scenarios. We derive, for the first time, its complete expression up to second order in redshift space and show that this improves detectability compared to previous evaluations at first order in real space. Moreover, we explore a few potential applications to use this observable to detect models with vector modes, or where different types of sources respond in different ways to the underlying modulating long mode, and anisotropic models with privileged directions in the sky. This shows how antisymmetric correlations can be a useful tool for testing exotic cosmological models.