scholarly journals Optimal void finders in weak lensing maps

2020 ◽  
Vol 500 (2) ◽  
pp. 2417-2439
Author(s):  
Christopher T Davies ◽  
Enrique Paillas ◽  
Marius Cautun ◽  
Baojiu Li
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Matter Field ◽  
Line Of Sight ◽  
Weak Lensing ◽  
Signal To Noise ◽  
Dominant Source ◽  
Good Compromise ◽  
Galaxy Distribution ◽  
Total Matter

ABSTRACT Cosmic voids are a key component of the large-scale structure that contain a plethora of cosmological information. Typically, voids are identified from the underlying galaxy distribution, which is a biased tracer of the total matter field. Previous works have shown that 2D voids identified in weak lensing (WL) maps – WL voids – correspond better to true underdense regions along the line of sight. In this work, we study how the properties of WL voids depend on the choice of void finder, by adapting several popular void finders. We present and discuss the differences between identifying voids directly in the convergence maps, and in the distribution of WL peaks. Particular effort has been made to test how these results are affected by galaxy shape noise (GSN), which is a dominant source of noise in WL observations. By studying the signal-to-noise ratios (S/N) for the tangential shear profile of each void finder, we find that voids identified directly in the convergence maps have the highest S/N but are also the ones most affected by GSN. Troughs are least affected by noise, but also have the lowest S/N. The tunnel algorithm, which identifies voids in the distribution of WL peaks, represents a good compromise between finding a large tangential shear S/N and mitigating the effect of GSN.

scholarly journals The Dark Matter filament between Abell 222/223

2014 ◽  
Vol 11 (S308) ◽  
pp. 193-198 ◽  
Author(s):  
Jörg P. Dietrich ◽  
Norbert Werner ◽  
Douglas Clowe ◽  
Alexis Finoguenov ◽  
Tom Kitching ◽  
...  
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Mass Measurement ◽  
Line Of Sight ◽  
Weak Lensing ◽  
X Ray ◽  
Hot Gas ◽  
Galaxy Distribution ◽  
The Galaxy ◽  
Long Time

AbstractWeak lensing detections and measurements of filaments have been elusive for a long time. The reason is that the low density contrast of filaments generally pushes the weak lensing signal to unobservably low scales. To nevertheless map the dark matter in filaments exquisite data and unusual systems are necessary. SuprimeCam observations of the supercluster system Abell 222/223 provided the required combination of excellent seeing images and a fortuitous alignment of the filament with the line-of-sight. This boosted the lensing signal to a detectable level and led to the first weak lensing mass measurement of a large-scale structure filament. The filament connecting Abell 222 and Abell 223 is now the only one traced by the galaxy distribution, dark matter, and X-ray emission from the hottest phase of the warm-hot intergalactic medium. The combination of these data allows us to put the first constraints on the hot gas fraction in filaments.

scholarly journals Weak lensing of large scale structure in the presence of screening

2015 ◽  
Vol 2015 (10) ◽  
pp. 036-036 ◽  
Author(s):  
Nicolas Tessore ◽  
Hans A. Winther ◽  
R. Benton Metcalf ◽  
Pedro G. Ferreira ◽  
Carlo Giocoli
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Weak Lensing

scholarly journals Anti-symmetric clustering signals in the observed power spectrum

2021 ◽  
Vol 2021 (12) ◽  
pp. 003
Author(s):  
José Fonseca ◽  
Chris Clarkson
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Euler Equation ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Power Spectra ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Signal To Noise ◽  
Peculiar Velocities

Abstract In this paper, we study how to directly measure the effect of peculiar velocities in the observed angular power spectra. We do this by constructing a new anti-symmetric estimator of Large Scale Structure using different dark matter tracers. We show that the Doppler term is the major component of our estimator and we show that we can measure it with a signal-to-noise ratio up to ∼ 50 using a futuristic SKAO HI galaxy survey. We demonstrate the utility of this estimator by using it to provide constraints on the Euler equation.

scholarly journals Weak Lensing by Large‐Scale Structure with the FIRST Radio Survey

2004 ◽  
Vol 617 (2) ◽  
pp. 794-810 ◽  
Author(s):  
Tzu‐Ching Chang ◽  
Alexandre Refregier ◽  
David J. Helfand
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Weak Lensing ◽  
Radio Survey

scholarly journals Faint Structures in Low Density Regions of the Nearby Universe

1999 ◽  
Vol 183 ◽  
pp. 256-256
Author(s):  
U. Lindner ◽  
K.J. Fricke ◽  
J. Einasto ◽  
M. Einasto
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Morphological Type ◽  
High Density ◽  
Low Density ◽  
Clusters Of Galaxies ◽  
Galaxy Distribution ◽  
The Galaxy ◽  
Empty Sphere ◽  
First Time

We present an investigation of the galaxy distribution in the huge underdense region between the Hercules, Coma and Local Superclusters, the so-called Northern Local Void (NLV), using void statistics (for details refer to Lindner et al. this Volume). Reshift data for galaxies and poor clusters of galaxies are available in low and high density regions as well. Samples of galaxies with different morphological type and various luminosity limits have been studied separately and void catalogues have been compiled from three different luminosity limited galaxy samples for the first time. Voids have been found using the empty sphere method which has the potential to detect and describe subtle structures in the galaxy distribution. Our approach is complementary to most other methods usually used in Large–Scale Structure studies.

scholarly journals Weak Lensing of the CMB by Large Scale Structure

2004 ◽  
Vol 2004 (IAUS225) ◽  
pp. 105-109 ◽  
Author(s):  
A. Amblard ◽  
C. Vale ◽  
M. White
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Weak Lensing

scholarly journals DO WE HAVE EVIDENCE FOR NEW PHYSICS IN THE SKY?

2006 ◽  
Vol 21 (01) ◽  
pp. 1-21 ◽  
Author(s):  
LAURA MERSINI-HOUGHTON
Keyword(s):  
String Theory ◽  
Large Scale ◽  
Recent Progress ◽  
Large Scale Structure ◽  
New Physics ◽  
Scale Structure ◽  
Weak Lensing ◽  
Source Terms ◽  
Crucial Importance

Predicting signatures of string theory on cosmological observables is not sufficient. Often the observable effects string theory may impact upon the cosmological arena which may equally be predicted by features of inflationary physics. The question: what observable signatures are unique to new physics, is thus of crucial importance for claiming evidence for the theory. Here we discuss recent progress in addressing the above question. The evidence relies on identifying discrepancies between the source terms that give rise to large scale structure (LSS) and CMB, by cross-correlating the weak lensing potential that maps LSS with the CMB spectra.

scholarly journals The accuracy of weak lensing simulations

2020 ◽  
Vol 493 (1) ◽  
pp. 305-319 ◽  
Author(s):  
Stefan Hilbert ◽  
Alexandre Barreira ◽  
Giulio Fabbian ◽  
Pablo Fosalba ◽  
Carlo Giocoli ◽  
...  
Keyword(s):  
Born Approximation ◽  
Power Spectra ◽  
Systematic Errors ◽  
Line Of Sight ◽  
Weak Lensing ◽  
Signal To Noise ◽  
Validation Test ◽  
Satisfactory Level ◽  
Level Of Agreement ◽  
Better Than

ABSTRACT We investigate the accuracy of weak lensing simulations by comparing the results of five independently developed lensing simulation codes run on the same input N-body simulation. Our comparison focuses on the lensing convergence maps produced by the codes, and in particular on the corresponding PDFs, power spectra, and peak counts. We find that the convergence power spectra of the lensing codes agree to $\lesssim 2{{\ \rm per\ cent}}$ out to scales ℓ ≈ 4000. For lensing peak counts, the agreement is better than $5{{\ \rm per\ cent}}$ for peaks with signal-to-noise ≲ 6. We also discuss the systematic errors due to the Born approximation, line-of-sight discretization, particle noise, and smoothing. The lensing codes tested deal in markedly different ways with these effects, but they none-the-less display a satisfactory level of agreement. Our results thus suggest that systematic errors due to the operation of existing lensing codes should be small. Moreover their impact on the convergence power spectra for a lensing simulation can be predicted given its numerical details, which may then serve as a validation test.

scholarly journals Primordial Non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Structure

2010 ◽  
Vol 2010 ◽  
pp. 1-64 ◽  
Author(s):  
Michele Liguori ◽  
Emiliano Sefusatti ◽  
James R. Fergusson ◽  
E. P. S. Shellard
Keyword(s):  
Cosmic Microwave Background ◽  
Large Scale ◽  
Initial Conditions ◽  
Temperature Fluctuations ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Future Prospects ◽  
Microwave Background ◽  
Galaxy Distribution ◽  
Non Gaussian

The most direct probe of non-Gaussian initial conditions has come from bispectrum measurements of temperature fluctuations in the Cosmic Microwave Background and of the matter and galaxy distribution at large scales. Such bispectrum estimators are expected to continue to provide the best constraints on the non-Gaussian parameters in future observations. We review and compare the theoretical and observational problems, current results, and future prospects for the detection of a nonvanishing primordial component in the bispectrum of the Cosmic Microwave Background and large-scale structure, and the relation to specific predictions from different inflationary models.

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