English
Related papers

Related papers: Sample variance in N--body simulations and impact …

200 papers

Constraining cosmology using weak gravitational lensing consists of comparing a measured feature vector of dimension $N_b$ with its simulated counterpart. An accurate estimate of the $N_b\times N_b$ feature covariance matrix $\mathbf{C}$ is…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-28 Andrea Petri , Zoltán Haiman , Morgan May

Forthcoming experiments will enable us to determine tomographic shear spectra at a high precision level. Most predictions about them have until now been biased on algorithms yielding the expected linear and non-linear spectrum of density…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Luciano Casarini , Silvio A. Bonometto , Stefano Borgani , Klaus Dolag , Giuseppe Murante , Marino Mezzetti , Luca Tornatore , Giuseppe La Vacca

We study the effect of box size on the matter power spectrum obtained via cosmological N-body simulations. Within the framework of the cosmic screening approach, we show that the relative deviation between the spectra for our largest…

General Relativity and Quantum Cosmology · Physics 2024-01-30 Maxim Eingorn , Ezgi Yilmaz , A. Emrah Yükselci , Alexander Zhuk

We quantify the bias caused by small simulation box size on weak lensing observables and covariances, considering both replication and super-sample effects for a range of higher-order statistics. Using two simulation suites -- one…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-26 Akira Tokiwa , Adrian E. Bayer , Joaquin Armijo , Jia Liu , Ryo Terasawa , Leander Thiele , Marcelo Alvarez , Linda Blot , Masahiro Takada

We present a general statistical framework for describing the effect of sample variance in the number counts of virialized objects and examine its effect on cosmological parameter estimation. Specifically, we consider effects of sample…

Astrophysics · Physics 2010-04-06 Wayne Hu , Andrey V. Kravtsov

Counts-in-cells are measured in the $\tau$CDM Virgo Hubble Volume simulation. This large N-body experiment has 10^9 particles in a cubic box of size 2000 h^{-1} Mpc. The unprecedented combination of size and resolution allows for the first…

Astrophysics · Physics 2009-10-31 Stéphane Colombi , István Szapudi , Adrian Jenkins , Jörg Colberg

In biospectroscopy, suitably annotated and statistically independent samples (e. g. patients, batches, etc.) for classifier training and testing are scarce and costly. Learning curves show the model performance as function of the training…

Applications · Statistics 2015-05-05 Claudia Beleites , Ute Neugebauer , Thomas Bocklitz , Christoph Krafft , Jürgen Popp

In Markov Chain Monte Carlo (MCMC) simulations, the thermal equilibria quantities are estimated by ensemble average over a sample set containing a large number of correlated samples. These samples are selected in accordance with the…

Data Analysis, Statistics and Probability · Physics 2015-01-08 J. Li , P. Vignal , S. Sun , V. M. Calo

(Abridged) We investigate and quantify the impact of finite simulation volume on weak lensing two- and four-point statistics. These {\it finite support} (FS) effects are modelled for several estimators, simulation box sizes and source…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Joachim Harnois-Deraps , Ludovic van Waerbeke

Upcoming weak lensing surveys will survey large cosmological volumes to measure the growth of cosmological structure with time and thereby constrain dark energy. One major systematic uncertainty in this process is the calibration of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Arun Kannawadi , Rachel Mandelbaum , Claire Lackner

We present results from a set of simulations designed to constrain the weak lensing shear calibration for the Hyper Suprime-Cam (HSC) survey. These simulations include HSC observing conditions and galaxy images from the Hubble Space…

N-Body simulations are a very important tool in the study of formation of large scale structures. Much of the progress in understanding the physics of high redshift universe and comparison with observations would not have been possible…

Astrophysics · Physics 2007-05-23 J. S. Bagla , Suryadeep Ray

We use N-body/photometric galaxy simulations to examine the impact of sample variance of spectroscopic redshift samples on the accuracy of photometric redshift (photo-z) determination and calibration of photo-z errors. We estimate the…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-02 Carlos E. Cunha , Dragan Huterer , Michael T. Busha , Risa H. Wechsler

Current best limits on the 21-cm signal during reionization are provided at large scales ($\gtrsim$100 Mpc). To model these scales, enormous simulation volumes are required which are computationally expensive. We find that the primary…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-21 Sambit K. Giri , Aurel Schneider , Francisco Maion , Raul E. Angulo

N-Body simulations are an important tool in the study of formation of large scale structures. Much of the progress in understanding the physics of galaxy clustering and comparison with observations would not have been possible without…

Astrophysics · Physics 2009-09-09 J. S. Bagla , Jayanti Prasad , Nishikanta Khandai

Recent advancements in multispectral (MS) and hyperspectral (HS) microscopy have focused on sensor and system improvements, yet sample processing remains overlooked. We conducted an analysis of the literature, revealing that 40 percent of…

We reproduced the results of CheXNet with fixed hyperparameters and 50 different random seeds to identify 14 finding in chest radiographs (x-rays). Because CheXNet fine-tunes a pre-trained DenseNet, the random seed affects the ordering of…

Computer Vision and Pattern Recognition · Computer Science 2019-12-28 John R. Zech , Jessica Zosa Forde , Michael L. Littman

Our interest has been to study the effect that scattered radiation has on contrast, signal-to-noise ratio and thickness reconstruction in digital mammographies. Using the GEANT code we have performed Monte-Carlo simulations of 25 kVp Mo/Mo…

Medical Physics · Physics 2009-09-29 Varlen Grabski , Maria-Ester Brandan

We compare the measurements of the bispectrum and the estimate of its covariance obtained from a set of different methods for the efficient generation of approximate dark matter halo catalogs to the same quantities obtained from full N-body…

In view of future high-precision large-scale structure surveys, it is important to quantify the percent and subpercent level effects in cosmological $N$-body simulations from which theoretical predictions are drawn. One such effect involves…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-27 B. Falck , N. McCullagh , M. C. Neyrinck , J. Wang , A. S. Szalay
‹ Prev 1 2 3 10 Next ›