REVIEW 6 cited by
21cm foregrounds and polarization leakage: a user's guide on cleaning and mitigation strategies
Not yet reviewed by Pith; the record is open.
This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.
SPECIMEN: schema-true, not a live event
T0 review · schema-true
One-sentence machine reading of the paper's core claim.
pith:XXXXXXXX · record.json · timestamp
abstract
The success of HI intensity mapping is largely dependent on how well 21cm foreground contamination can be controlled. In order to progress our understanding further, we present a range of simulated foreground data from four different $\sim3000$\,deg$^2$ sky regions, with and without effects from polarization leakage. Combining these with underlying cosmological HI simulations creates a range of single-dish intensity mapping test cases that require different foreground treatments. This allows us to conduct the most generalized study to date into 21cm foregrounds and their cleaning techniques for the post-reionization era. We first provide a pedagogical review of the most commonly used blind foreground removal techniques (PCA/SVD, FASTICA, GMCA). We also trial a non-blind parametric fitting technique and discuss potential hybridization of methods. We highlight the similarities and differences in these techniques finding that the blind methods produce near equivalent results, and we explain the fundamental reasons for this. The simulations allow an exact decomposition of the resulting cleaned data and we analyse the contribution from foreground residuals. Our results demonstrate that polarized foreground residuals should be generally subdominant to HI on small scales ($k\gtrsim0.1\,h\,\text{Mpc}^{-1}$). However, on larger scales, results are more region dependent. In some cases, aggressive cleans severely damp HI power but still leave dominant foreground residuals. We also demonstrate the gain from cross-correlations with optical galaxy surveys, where extreme levels of residual foregrounds can be circumvented. However, these residuals still contribute to errors and we discuss the optimal balance between over- and under-cleaning.
Forward citations
Cited by 6 Pith papers
-
Impact of numerical stability in Bayesian noise wave calibration on global 21-cm experiments
Near-collinearity of noise-source and load design-matrix columns makes REACH’s five-parameter Bayesian calibration non-reproducible; a four-parameter Chebyshev fit with hot-load T_NS(ν) recovery and spike masking stab...
-
An Alcock-Paczynski Test on Reionization Bubbles for Cosmology
Stacks of reionization HII bubbles act as standard spheres, allowing a forecast ~2% measurement of D_A H at z=7.5 with SKA-like 21-cm data.
-
Foreground Subtraction with a Tensor-Based Oriented Singular Value Decomposition Method for HI Experiments
A tensor-oriented singular value decomposition can subtract radio foregrounds from 21 cm intensity mapping data while preserving more cosmological signal than standard PCA.
-
Deep learning with hybrid frequency differencing and principal component analysis for 21-cm foreground and beam mitigation
A two-channel UNet combining frequency differencing and PCA preprocessing recovers the 21-cm HI power spectrum at large scales under realistic beam effects, improving cross-correlation by 5-8% over single-channel baselines.
-
Cosmology with HI Intensity Mapping
SKAO HI intensity mapping forecasts yield competitive LambdaCDM constraints (e.g. H0 to ~0.3 km/s/Mpc optimistic) via power spectrum, BAO, bispectrum and stacking, complementary to CMB and optical surveys.
-
Beyond {\Lambda}CDM with the SKA Observatory -- II: Unveiling the Secrets of the Early Universe
Updated SKAO-AA4 forecasts show multi-tracer HI+galaxy analyses can reach σ(f_local_NL)≲1 and improve αs bounds by tens of percent when combined with future CMB, while foregrounds and GR light-cone effects remain the ...
Discussion (0). Continue with ORCID to comment.