Multi-tracer intensity mapping: Cross-correlations, Line noise & Decorrelation

Abstract

Line intensity mapping (LIM) is a rapidly emerging technique for constraining cosmology and galaxy formation using multi-frequency, low angular resolution maps. Many LIM applications crucially rely on cross-correlations of two line intensity maps, or of intensity maps with galaxy surveys or galaxy/CMB lensing. We present a consistent halo model to predict all these cross-correlations and enable joint analyses, in 3D redshift-space and for 2D projected maps. We extend the conditional luminosity function formalism to the multi-line case, to consistently account for correlated scatter between multiple galaxy line luminosities. This allows us to model the scale-dependent decorrelation between two line intensity maps, a key input for foreground rejection and for approaches that estimate auto-spectra from cross-spectra. This also enables LIM cross-correlations to reveal astrophysical properties of the interstellar medium inacessible with LIM auto-spectra. We expose the different sources of luminosity scatter or "line noise" in LIM, and clarify their effects on the 1-halo and galaxy shot noise terms. In particular, we show that the effective number density of halos can in some cases exceed that of galaxies, counterintuitively. Using observational and simulation input, we implement this halo model for the H$\alpha$, [Oiii], Lyman-$\alpha$, CO and [Cii] lines. We encourage observers and simulators to measure galaxy luminosity correlation coefficients for pairs of lines whenever possible. Our code is publicly available at https://github.com/EmmanuelSchaan/HaloGen/tree/LIM . In a companion paper, we use this halo model formalism and code to highlight the degeneracies between cosmology and astrophysics in LIM, and to compare the LIM observables to galaxy detection for a number of surveys.

Accepted in JCAP on 05/03/2021. Code publicly available at https://github.com/EmmanuelSchaan/HaloGen/tree/LIM

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Cited by in corpus (35)

• CCAT-prime Collaboration: Science Goals and Forecasts with Prime-Cam on the Fred Young Submillimeter Telescope
• Line-Intensity Mapping: Theory Review
• The THESAN project: predictions for multi-tracer line intensity mapping in the epoch of reionization
• An empirical representation of a physical model for the ISM [CII], CO, and [CI] emission at redshift $1\le z\le 9$
• Priors on red galaxy stochasticity from hybrid effective field theory
• Precision Tests of CO and [CII] Power Spectra Models against Simulated Intensity Maps
• COMAP Early Science: VII. Prospects for CO Intensity Mapping at Reionization
• Astrophysics & Cosmology from Line Intensity Mapping vs Galaxy Surveys
• An Intensity Mapping Constraint on the CO-Galaxy Cross Power Spectrum at Redshift ~ 3
• LIMFAST. II. Line Intensity Mapping as a Probe of High-Redshift Galaxy Formation
• Revisiting the [C II]${}_{158\mu \text{m}}$ line-intensity mapping power spectrum from the EoR using non-uniform line-luminosity scatter
• Forecasts and Statistical Insights for Line Intensity Mapping Cross-Correlations: A Case Study with 21cm x [CII]
• A multi-tracer empirically-driven approach to line-intensity mapping lightcones
• A new probe of the high-redshift Universe: nulling CMB lensing with interloper-free "LIM-pair" lensing
• Extragalactic Science with the Experiment for Cryogenic Large-aperture Intensity Mapping
• Unveiling cosmological information on small scales with line intensity mapping
• Subtracting the kinetic Sunyaev-Zeldovich effect from the cosmic microwave background with surveys of large-scale structure
• Characterizing the Conditional Galaxy Property Distribution using Gaussian Mixture Models
• Infrared fine-structure lines at high redshift
• Cosmological Constraints on the Global Star Formation Law of Galaxies: Insights From Baryon Acoustic Oscillation Intensity Mapping
• Characteristic Functions for Cosmological Cross-Correlations
• On the contributions of extragalactic CO emission lines to ground-based CMB observations
• Constraining Cosmology With the CMB $\times$ LIM-Nulling Convergence
• Impact of astrophysical scatter on the Epoch of Reionization [H I]${}_{21cm}$ bispectrum
• Bayesian Multi-line Intensity Mapping
• Towards Optimal Foreground Mitigation Strategies for Interferometric HI Intensity Mapping in the Low-Redshift Universe
• A statistical framework for recovering intensity mapping autocorrelations from crosscorrelations
• The power spectrum of galaxies from large to small scales: a line-intensity mapping perspective
• Leveraging cross-correlations and linear covariance-based filtering for line-intensity map reconstructions at linear scales
• Scatter in the star formation rate-halo mass relation: secondary bias and its impact on line-intensity mapping
• Removal of interloper contamination to line-intensity maps using correlations with ancillary tracers of the large-scale structure
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• Cross-correlations between mm-wave line-intensity mapping and weak lensing surveys: preliminary consideration of long-term prospects