Cosmology and Nongalactic Astrophysics · arXiv:1812.02104 v4 · submitted 5 Dec 2018
A blind method to recover the mask of a deep galaxy survey
The paper says
“Using a set of 20 large mock catalogs covering 1/4-th of the sky and number-matched to Hα emitters to mimic an Euclid-like sample, we demonstrate that our method can reconstruct the mask and its angular clustering at scales ℓ < 100, beyond which the cosmological signal becomes dominant.”
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Abstract
We present a blind method to determine the properties of a foreground contamination, given by a visibility mask, that affects a deep galaxy survey. Angular cross correlations of density fields in different redshift bins are expected to vanish (apart from a contribution due to lensing), but are sensitive to the presence of a foreground that modulates the flux limit across the sky. After formalizing the expected effect of a foreground mask on the measured galaxy density, under a linear, luminosity-dependent bias model for galaxies, we construct two estimators that single out the mask contribution if a sufficient number of independent redshift bins is available. These estimators are combined to give a reconstruction of the mask. We use Milky-Way reddening as a prototype for the mask. Using a set of 20 large mock catalogs covering 1/4-th of the sky and number-matched to Hα emitters to mimic an Euclid-like sample, we demonstrate that our method can reconstruct the mask and its angular clustering at scales ℓ < 100, beyond which the cosmological signal becomes dominant. The uncertainty of this reconstruction is quantified to be 1/3-rd of the sample variance of the signal. Such a reconstruction requires knowledge of the average and square average of the mask, but we show that it is possible to recover this information either from external models or internally from the data. It also relies on knowledge of how the impact of the foreground changes with redshift (due to the extinction curve in our case), but this can be tightly constrained by cross correlations of different redshift bins. The strong points of this blind reconstruction technique lies in the ability to find "unknown unknowns" that affect a survey, and in the facility to quantify, using sets of mock catalogs, how its uncertainty propagates to clustering measurements. [Abridged]
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abstract compiled · 2026-09-23 · no language-model review
How the main claim is stated: asserted 1.00
What the abstract itself states, as probabilities: claims first 0.05 · states limitation 0.92 · human participants 0.01 · controlled comparison 0.06 · randomized assignment 0.01 · states quantitative result 0.98 · compares with prior results 0.08 · mentions code or data availability 0.03
The abstract, sentence by sentence
This table labels the abstract only (arXiv listing abstract v4). The number is the probability the classifier gave the label.
| Sentence | Role | The authors' own work | States the main conclusion | Strength |
|---|---|---|---|---|
| We present a blind method to determine the properties of a foreground contamination, given by a visibility mask, that affects a deep galaxy survey. | contribution 1.00 | 0.94 | 0.24 | asserted 1.00 |
| Angular cross correlations of density fields in different redshift bins are expected to vanish (apart from a contribution due to lensing), but are sensitive to the presence of a foreground that modulates the flux limit across the sky. | background 0.99 | 0.09 | 0.04 | asserted 0.85 |
| After formalizing the expected effect of a foreground mask on the measured galaxy density, under a linear, luminosity-dependent bias model for galaxies, we construct two estimators that single out the mask contribution if a sufficient number of independent redshift bins is available. | method 0.92 | 0.92 | 0.11 | asserted 0.89 |
| These estimators are combined to give a reconstruction of the mask. | method 0.89 | 0.91 | 0.19 | asserted 1.00 |
| We use Milky-Way reddening as a prototype for the mask. | method 0.89 | 0.82 | 0.03 | asserted 0.99 |
| Using a set of 20 large mock catalogs covering $1/4$-th of the sky and number-matched to $H\alpha$ emitters to mimic an Euclid-like sample, we demonstrate that our method can reconstruct the mask and its angular clustering at scales $\ell<100$, beyond which the cosmological signal becomes dominant. | result 0.76 | 0.96 | 0.39 | asserted 1.00 |
| The uncertainty of this reconstruction is quantified to be $1/3$-rd of the sample variance of the signal. | result 1.00 | 0.94 | 0.12 | asserted 1.00 |
| Such a reconstruction requires knowledge of the average and square average of the mask, but we show that it is possible to recover this information either from external models or internally from the data. | limitation 0.65 | 0.88 | 0.08 | asserted 0.71 |
| It also relies on knowledge of how the impact of the foreground changes with redshift (due to the extinction curve in our case), but this can be tightly constrained by cross correlations of different redshift bins. | limitation 0.78 | 0.67 | 0.05 | asserted 0.77 |
| The strong points of this blind reconstruction technique lies in the ability to find "unknown unknowns" that affect a survey, and in the facility to quantify, using sets of mock catalogs, how its uncertainty propagates to clustering measurements. [Abridged] | interpretation 0.94 | 0.79 | 0.37 | asserted 1.00 |
What kind of paper the classifier reports this is: method or tool 1.00 · evidence from simulation or computation 1.00
What was examined, and what was not
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Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 7,824 input tokens.
Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. This record as JSON
Cited by 2 Pith papers
Reviewed papers on Pith that cite this one. The full citation record
- Systematic-free inference of the cosmic matter density field from SDSS3-BOSS data astro-ph.CO · Sep 2019
- Cosmology with dropout selection: Straw-man surveys and CMB lensing astro-ph.CO · Apr 2019
How the literature uses it
4 arXiv papers cite this in 5 sentences
Papers citing it · 4 sentences without a confident label
Cites it as support 1 paper
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The capability to account for `unknown unknowns' is also the primary motivation behind the blind method for the visibility mask reconstruction recently proposed by [ref] .
Explicit Bayesian treatment of unknown foreground contaminations in galaxy surveys · Introduction · 0.98
What it cites · 22 sentences without a confident label
Uses the method or tool of 10 papers
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The catalogs were generated with the [http://adlibitum.oats.inaf.it/monaco/pinocchio.html] approximate method [ref] ; see [ref] for a review on this technique.
An accurate tool for the fast generation of dark matter halo catalogs · Simulated catalogs · 1.00
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The catalogs were generated with the [http://adlibitum.oats.inaf.it/monaco/pinocchio.html] approximate method [ref] ; see [ref] for a review on this technique.
Improving fast generation of halo catalogs with higher-order Lagrangian perturbation theory · Simulated catalogs · 1.00
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The catalogs were generated with the [http://adlibitum.oats.inaf.it/monaco/pinocchio.html] approximate method [ref] ; see [ref] for a review on this technique.
Approximate methods for the generation of dark matter halo catalogs in the age of precision cosmology · Simulated catalogs · 1.00
Uses data or values from 2 papers
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Assuming a one-to-one relation between halo mass and galaxy luminosity in the $Hα$ line (as in a naive Halo Occupation Distribution model - HOD - with one single galaxy in each halo), halos were number-matched to galaxies using the luminosity function of model 1 of Pozzetti et al. (2016) [ref] .
Modelling the number density of Halpha emitters for future spectroscopic near-IR space missions · Simulated catalogs · 0.93
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Planck has constrained this parameter to be $f_nl=0.8±5.0$ [ref] .
Planck 2015 results. XVII. Constraints on primordial non-Gaussianity · Introduction · 0.94
Cites as support 2 papers
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Indeed, as shown in Ref. [ref] , it is crucial to being able to recover information from scales larger than $ℓ_min ≲10$ to provide constraints of the order $σ( f_nl ) ∼𝒪 ( 1 )$, which will be able to discriminate between different inflationary models.
Constraining ultra large-scale cosmology with multiple tracers in optical and radio surveys · Conclusions · 0.98
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This is no surprise, because the contribution of lensing (whose level is appreciable in the right panels) is negligible for auto correlations with respect to clustering and RSD for redshift bins of the width $Δz =0.1$ (see e.g. [ref] ).
Cosmological Parameter Estimation with Large Scale Structure Observations · The contribution of lensing · 0.96
Cites as background 8 papers
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The next generation of galaxy surveys, like Euclid [ref] , DESI [ref] , WFIRST [ref] , LSST [ref] , eBoss [ref] and the SKA [ref] surveys, will map large fractions of the sky, going deep, well beyond redshift one, and collecting data for billions of galaxies.
Cosmology with the SKA -- overview · Introduction · 0.99
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The next generation of galaxy surveys, like Euclid [ref] , DESI [ref] , WFIRST [ref] , LSST [ref] , eBoss [ref] and the SKA [ref] surveys, will map large fractions of the sky, going deep, well beyond redshift one, and collecting data for billions of galaxies.
The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Overview and Early Data · Introduction · 0.99
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The next generation of galaxy surveys, like Euclid [ref] , DESI [ref] , WFIRST [ref] , LSST [ref] , eBoss [ref] and the SKA [ref] surveys, will map large fractions of the sky, going deep, well beyond redshift one, and collecting data for billions of galaxies.
LSST Science Book, Version 2.0 · Introduction · 0.99
Challenges and discussion
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