A statistical framework for recovering intensity mapping autocorrelations from crosscorrelations

Abstract

Intensity mapping experiments will soon have surveyed large swathes of the sky, providing information about the underlying matter distribution of the early universe. The resulting maps can be used to recover statistical information, such as the power spectrum, about the measured spectral lines (for example, HI, [CII], and [OIII]). However precise power spectrum measurements, such as the 21 cm autocorrelation, continue to be challenged by the presence of bright foregrounds and non-trivial systematics. By crosscorrelating different data sets, it may be possible to mitigate the effects of both foreground uncertainty and uncorrelated instrumental systematics. Beyond their own merit, crosscorrelations could also be used to recover autocorrelation information. Such a technique was proposed in Beane et al. (2019) for recovering the 21 cm power spectrum. Generalizing their result, we develop a statistical framework for combining multiple crosscorrelation signals in order to infer information about the corresponding autocorrelations. We do this first within the Least Squares Estimator (LSE) framework, and show how one can derive their estimator, along with several alternative estimators. We also investigate the posterior distribution of recovered autocorrelation and associated model parameters. We find that for certain noise regimes and cosmological signal modeling assumptions this procedure is effective at recovering autospectra from a set of crosscorrelations. Finally, we showcase our framework in the context of several near-future line intensity mapping experiments.

18 pages, 13 figures, to be submitted to MNRAS

References in corpus (14)

• Measurement of 21 cm brightness fluctuations at z ~ 0.8 in cross-correlation
• The Epoch of Reionization Window: I. Mathematical Formalism
• Line-Intensity Mapping: 2017 Status Report
• The Spatially Resolved [CII] Cooling Line Deficit in Galaxies
• The Origins of [CII] Emission in Local Star-forming Galaxies
• Intensity mapping of [CII] from early galaxies
• The Absence of [CII] 158$\mu$m Emission in Spectroscopically-Confirmed Galaxies at $z>8$
• First Detection of the [OIII] 88 micron Line at High Redshifts: Characterizing the Starburst and Narrow Line Regions in Extreme Luminosity Systems
• Towards simulating and quantifying the light-cone EoR 21-cm signal
• [OIII] emission line as a tracer of star-forming galaxies at high redshifts: Comparison between H$\alpha$ and [OIII] emitters at $z$=2.23 in HiZELS
• A GBT Survey for HI 21 cm Absorption in the Disks and Halos of Low-Redshift Galaxies
• Constraining low redshift [CII] Emission by Cross-Correlating FIRAS and BOSS Data
• Line of sight anisotropies in the Cosmic Dawn and EoR 21-cm power spectrum
• Overview and status of EXCLAIM, the experiment for cryogenic large-aperture intensity mapping

Cited by in corpus (4)

• Forecasts and Statistical Insights for Line Intensity Mapping Cross-Correlations: A Case Study with 21cm x [CII]
• Rapid and Late Cosmic Reionization Driven by Massive Galaxies: a Joint Analysis of Constraints from 21-cm, Lyman Line & CMB Data Sets
• The 21cm-galaxy cross-correlation: Realistic forecast for 21cm signal detection and reionisation constraints
• A New Boundary Condition on Reionization