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Lagrangian data assimilation aims to recover hidden Eulerian flow fields from sparse, indirect observations of moving tracers. This problem is challenging because tracer trajectories are nonlinearly coupled with the underlying flow, making…

Computational Engineering, Finance, and Science · Computer Science 2026-03-17 Zhongrui Wang , Chuanqi Chen , Jin-Long Wu , Nan Chen

In hierarchical models of gravitational clustering, virialized haloes are biased tracers of the matter distribution. As discussed by Mo & White (1996), this bias is nonlinear and stochastic. They developed a model which allows one to write…

Astrophysics · Physics 2009-10-30 Ravi K. Sheth , Gerard Lemson

We present \emph{Unified Lagrangian Perturbation Theory} (ULPT), a perturbative framework for consistently modeling galaxy density fluctuations across real space, redshift space, and post-reconstruction fields. Unlike existing approaches…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-08 Naonori Sugiyama

To perform precise and accurate photometric catalogue cross-matches -- assigning counterparts between two separate datasets -- we need to describe all possible sources of uncertainty in object position. With ever-increasing time baselines…

Solar and Stellar Astrophysics · Physics 2023-01-23 Tom J. Wilson

We examine the Lagrangian divergence of the displacement field, arguably a more natural object than the density in a Lagrangian description of cosmological large-scale structure. This quantity, which we denote \psi, quantifies the…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-17 Mark C. Neyrinck

We characterize the nonlinear evolution of the baryon acoustic feature as traced by the dark matter and halos, using a combination of perturbation theory and N-body simulations. We confirm that the acoustic peak traced by the dark matter is…

Cosmology and Nongalactic Astrophysics · Physics 2009-09-24 Nikhil Padmanabhan , Martin White

Studies of dark matter lie at the interface of collider physics, astrophysics and cosmology. Constraining models featuring dark matter candidates entails the capability to provide accurate predictions for large sets of observables and…

We study analytically the collapse of an initially smooth, cold, self-gravitating collisionless system in one dimension. The system is described as a central "S" shape in phase-space surrounded by a nearly stationary halo acting locally…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Stephane Colombi

We derive the Edgeworth streaming model (ESM) for the redshift space correlation function starting from an arbitrary distribution function for biased tracers of dark matter by considering its two-point statistics and show that it reduces to…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-16 Cora Uhlemann , Michael Kopp , Thomas Haugg

We combine the physics of the ellipsoidal collapse model with the excursion set theory to study the shapes of dark matter halos. In particular, we develop an analytic approximation to the nonlinear evolution that is more accurate than the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Graziano Rossi , Ravi K. Sheth , Giuseppe Tormen

The baryon acoustic oscillation (BAO) feature provides an important distance scale for the measurement of the expansion history of the Universe. Theoretical models of the BAO in the distribution of biased tracers of the large scale…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-01 Tobias Baldauf , Vincent Desjacques

We present a new method that simultaneously solves for cosmology and galaxy bias on non-linear scales. The method uses the halo model to analytically describe the (non-linear) matter distribution, and the conditional luminosity function…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Frank van den Bosch , Surhud More , Marcello Cacciato , Houjun Mo , Xiaohu Yang

Previous studies using numerical simulations have demonstrated that the shape of the cosmic web can be described by studying the Lagrangian displacement field. We extend these analyses, showing that it is now possible to perform a…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-28 Florent Leclercq , Jens Jasche , Guilhem Lavaux , Benjamin Wandelt , Will Percival

Modern galaxy surveys demand extensive survey volumes and resolutions surpassing current dark matter-only simulations' capabilities. To address this, many methods employ effective bias models on the dark matter field to approximate object…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-08 Daniel Forero-Sánchez , Francisco-Shu Kitaura , Francesco Sinigaglia , Jose María Coloma-Nadal , Jean-Paul Kneib

We develop a new approach to study the nonlinear evolution in the large-scale structure of the Universe both in real space and in redshift space, extending the standard perturbation theory of gravitational instability. Infinite series of…

Astrophysics · Physics 2008-11-26 Takahiko Matsubara

We formulate the Lagrangian perturbation theory of galaxy intrinsic alignments and compute the resulting auto and cross power spectra of galaxy shapes, densities and matter to 1-loop order. Our model represents a consistent effective-theory…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-03 Shi-Fan Chen , Nickolas Kokron

The physical interpretation of cold dark matter perturbations is clarified by associating Bertschinger's Poisson gauge with a Eulerian/observer's frame of reference. We obtain such an association by using a Lagrangian approach to…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-27 Cornelius Rampf

We build a simple analytical model for the bias of dark matter halos that applies to objects defined by an arbitrary density threshold, $200\leq\deltas\leq 1600$, and that provides accurate predictions from low-mass to high-mass halos. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Patrick Valageas

There are two main strategies for improving the projection-based reduced order model (ROM) accuracy: (i) improving the ROM, i.e., adding new terms to the standard ROM; and (ii) improving the ROM basis, i.e., constructing ROM bases that…

Fluid Dynamics · Physics 2020-11-09 Xuping Xie , Peter J. Nolan , Shane D. Ross , Changhong Mou , Traian Iliescu

We present a stochastic approach to the spatial clustering of dark matter haloes in Lagrangian space. Our formalism is based on a local formulation of the `excursion set' approach by Bond et al., which automatically accounts for the…

Astrophysics · Physics 2009-10-30 Cristiano Porciani , Sabino Matarrese , Francesco Lucchin , Paolo Catelan