Cross-correlations between mm-wave line-intensity mapping and weak lensing surveys: preliminary consideration of long-term prospects

Abstract

The field of millimetre-wave line-intensity mapping (LIM) is seeing increased experimental activity with pathfinder surveys already deployed or deploying in the next few years, making spectroscopic measurements of unresolved atomic and molecular line emission tracing the large-scale structure of the Universe. The next decade will also see the Rubin Observatory Legacy Survey of Space and Time (LSST) undertake a photometric galaxy survey programme of unprecedented scope, including measurements of cosmic shear exploiting weak gravitational lensing (WL) of background galaxies to map projected large-scale structure. We consider prospects for detecting angular cross power spectra between non-tomographic cosmic shear and mm-wave LIM surveys that measure emission from CO lines at 𝑧 = 0.5-1. We forecast that once the LSST Year 10 WL dataset is available, a future LIM experiment, conceivably deployed in the next 10-15 years, would enable such a cross-correlation detection with an overall signal-to-noise ratio of 50, although the current pathfinder generation of CO/[C ] surveys are more likely to achieve a marginal 2𝜎 detection against an earlier-stage LSST WL dataset. The signal has modest astrophysical constraining power yielding competitive constraints on cosmic molecular gas density at 𝑧 1, and degeneracies between astrophysical parameters and the intrinsic alignment amplitude mean that external information on either one could allow the cross-correlation analysis to significantly improve its constraints on the other.

Cosmological Constraints on the Global Star Formation Law of Galaxies: Insights from Baryon Acoustic Oscillation Intensity Mapping

“…In particular, the tight connection between the emission line production and the astrophysics of interstellar gas of galaxies makes LIM a promising statistical probe of galaxy evolution. Historically, large-scale fluctuations of line intensity fields have been mainly considered for cosmological applications, such as probing alternative dark matter models, dark energy, gravitational lensing, neutrino properties, and the primordial non-Gaussianity (e.g., Sitwell et al 2014;Karkare & Bird 2018;Bernal et al 2019;Liu & Breysse 2021;Chung 2022;Maniyar et al 2022;Moradinezhad Dizgah et al 2022). The majority of astrophysical explorations of LIM have been focusing on small, nonlinear scales, where astrophysical processes of galaxy evolution are manifested through their effects on the one-halo or shot-noise components of the LIM power spectrum (e.g., Wolz et al 2017;Breysse & Alexandroff 2019;Mas-Ribas & Chang 2020;Schaan & White 2021).…”

Cosmological Constraints on the Global Star Formation Law of Galaxies: Insights From Baryon Acoustic Oscillation Intensity Mapping

“…In particular, the tight connection between the emission-line production and the astrophysics of interstellar gas of galaxies makes LIM a promising statistical probe of galaxy evolution. Historically, large-scale fluctuations of line intensity fields have been mainly considered for cosmological applications, such as probing alternative dark matter models, dark energy, gravitational lensing, neutrino properties, and the primordial non-Gaussianity (e.g., Sitwell et al 2014;Karkare & Bird 2018;Bernal et al 2019;Liu & Breysse 2021;Chung 2022;Maniyar et al 2022;Moradinezhad Dizgah et al 2022). The majority of astrophysical explorations of LIM have been focusing on small, non-linear scales, where astrophysical processes of galaxy evolution are manifested through their effects on the one-halo or shot-noise components of the LIM power spectrum (e.g., Wolz et al 2017;Breysse & Alexandroff 2019;Mas-Ribas & Chang 2020;Schaan & White 2021).…”