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We propose the use of robust, Bayesian methods for estimating extragalactic distance errors in multi-measurement catalogs. We seek to improve upon the more commonly used frequentist propagation-of-error methods, as they fail to explain both…

Instrumentation and Methods for Astrophysics · Physics 2019-03-13 Germán Chaparro Molano , Juan Carlos Cuervo , Oscar Alberto Restrepo Gaitán , Sergio Torres Arzayús

Reconstructing the large scale density and velocity fields from surveys of galaxy distances, is a major challenge for cosmography. The data is very noisy and sparse. Estimated distances, and thereby peculiar velocities, are strongly…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-21 Aurélien Valade , Noam I Libeskind , Yehuda Hoffman , Simon Pfeifer

We present a Bayesian reconstruction method which maps a galaxy distribution from redshift-space to real-space inferring the distances of the individual galaxies. The method is based on sampling density fields assuming a lognormal prior…

We consider a measure of the peculiar velocity field derived from the Mark III compilation of 2900 spiral galaxies (Willick \etal 1996b), using an analysis that is substantially free of bias (Nusser and Davis 1995). We expand the velocity…

Astrophysics · Physics 2009-10-28 Marc Davis , Adi Nusser , Jeff Willick

We formulate and solve a Bayesian inverse Navier-Stokes (N-S) problem that assimilates velocimetry data in order to jointly reconstruct a 3D flow field and learn the unknown N-S parameters, including the boundary position. By hardwiring a…

Due to our vantage point in the disk of the Galaxy, its 3D structure is not directly accessible. However, knowing the spatial distribution, e.g. of atomic and molecular hydrogen gas is of great importance for interpreting and modelling…

Astrophysics of Galaxies · Physics 2023-09-26 Laurin Söding , Philipp Mertsch , Vo Hong Minh Phan

We present a new method for fitting peculiar velocity models to complete flux limited magnitude-redshifts catalogues, using the luminosity function of the sources as a distance indicator.The method is characterised by its robustness. In…

Astrophysics · Physics 2009-10-31 Stephane Rauzy , Martin A. Hendry

Turbulence is a complex phenomenon that has a chaotic nature with multiple spatio-temporal scales, making predictions of turbulent flows a challenging topic. Nowadays, an abundance of high-fidelity databases can be generated by experimental…

Fluid Dynamics · Physics 2022-08-12 Mustafa Z. Yousif , Linqi Yu , Sergio Hoyas , Ricardo Vinuesa , HeeChang Lim

The peculiar motion of the host galaxies introduces bias in estimating cosmological parameters from supernova data. The coherent component of the peculiar motion is usually corrected for using velocity field reconstruction based on the…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-07 Ujjwal Upadhyay , Tarun Deep Saini , Shiv K. Sethi

An algorithm to estimate motion from satellite imagery is presented. Dense displacement fields are computed from time-separated images of of significant convective activity using a Bayesian formulation of the motion estimation problem.…

Atmospheric and Oceanic Physics · Physics 2007-05-23 Sai Ravela , Virat Chatdarong

We present a novel algorithm based on a Bayesian method for 2D tilted-ring analysis of disk galaxy velocity fields. Compared to the conventional algorithms based on a chi-squared minimisation procedure, this new Bayesian-based algorithm…

Astrophysics of Galaxies · Physics 2017-11-29 Se-Heon Oh , Lister Staveley-Smith , Kristine Spekkens , Peter Kamphuis , Bärbel S. Koribalski

We develop a deep learning technique to infer the non-linear velocity field from the dark matter density field. The deep learning architecture we use is an "U-net" style convolutional neural network, which consists of 15 convolution layers…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-21 Ziyong Wu , Zhenyu Zhang , Shuyang Pan , Haitao Miao , Xin Wang , Cristiano G. Sabiu , Jaime Forero-Romero , Yang Wang , Xiao-Dong Li

We introduce NIFTY, "Numerical Information Field Theory", a software package for the development of Bayesian signal inference algorithms that operate independently from any underlying spatial grid and its resolution. A large number of…

Instrumentation and Methods for Astrophysics · Physics 2014-12-24 Marco Selig

3D Lidar imaging can be a challenging modality when using multiple wavelengths, or when imaging in high noise environments (e.g., imaging through obscurants). This paper presents a hierarchical Bayesian algorithm for the robust…

Image and Video Processing · Electrical Eng. & Systems 2021-03-19 Abderrahim Halimi , Aurora Maccarone , Robert Lamb , Gerald S. Buller , Stephen McLaughlin

We discuss the implementation of Bayesian inversion methods in order to recover the properties of the intergalactic medium from observations of the neutral hydrogen Lyman-$\alpha$ absorptions observed in the spectra of high redshift quasars…

Astrophysics · Physics 2009-11-06 C. Pichon , J. L. Vergely , E. Rollinde , S. Colombi , P. Petitjean

We present a new method for recovering the cosmological density, velocity, and potential fields from all-sky redshift catalogues. The method is based on an expansion of the fields in orthogonal radial (Bessel) and angular (spherical…

Astrophysics · Physics 2015-06-24 Karl Fisher , Ofer Lahav , Yehuda Hoffman , Donald Lynden-Bell , Saleem Zaroubi

We present a method for reconstructing two-dimensional velocity fields at specified length scales using observational data from tracer particles in a flow, without the need for interpolation or smoothing. The algorithm, adapted from…

Fluid Dynamics · Physics 2010-04-28 Douglas H. Kelley , Nicholas T. Ouellette

We describe and characterize a method for estimating the pressure field corresponding to velocity field measurements, such as those obtained by using particle image velocimetry. The pressure gradient is estimated from a time series of…

Fluid Dynamics · Physics 2014-01-22 John O. Dabiri , Sanjeeb Bose , Brad J. Gemmell , Sean P. Colin , John H. Costello

Cosmic shear estimation is an essential scientific goal for large galaxy surveys. It refers to the coherent distortion of distant galaxy images due to weak gravitational lensing along the line of sight. It can be used as a tracer of the…

Machine Learning · Computer Science 2021-04-21 Claire Theobald , Bastien Arcelin , Frédéric Pennerath , Brieuc Conan-Guez , Miguel Couceiro , Amedeo Napoli

We present a Bayesian inference approach to estimating the cumulative mass profile and mean squared velocity profile of a globular cluster given the spatial and kinematic information of its stars. Mock globular clusters with a range of…

Astrophysics of Galaxies · Physics 2022-03-09 Gwendolyn M. Eadie , Jeremy J. Webb , Jeffrey S. Rosenthal