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We present a suite of direct $N$-body simulations of the Hyades open cluster and its tidal stream in a Milky Way potential that includes a rotating bar and spiral arms. Using the high-resolution code PETAR and an AGAMA-based multi-component…

Astrophysics of Galaxies · Physics 2026-04-01 Zi-yi Zhou , Long Wang , Tereza Jerabkova , Zhenghao He

Flattened axisymmetric galactic potentials are known to host minor orbit families surrounding orbits with commensurable frequencies. The behavior of orbits that belong to these orbit families is fundamentally different than that of typical…

Astrophysics of Galaxies · Physics 2023-01-09 Tomer D. Yavetz , Kathryn V. Johnston , Sarah Pearson , Adrian M. Price-Whelan , Martin D. Weinberg

We study the evolution of streams in a time-dependent spherical gravitational potential. Our goal is to establish what are the imprints of this time evolution on the properties of streams as well as their observability. To this end, we have…

Astrophysics of Galaxies · Physics 2015-12-02 Hans J. T. Buist , Amina Helmi

We develop a semi-analytic method for determining the phase-space population of tidal debris along the orbit of a disrupting satellite galaxy and illustrate its use with a number of applications. We use this method to analyze Zhao's…

Astrophysics · Physics 2010-04-06 Kathryn V. Johnston

Computing the approximate quantiles or ranks of a stream is a fundamental task in data monitoring. Given a stream of elements $x_1, x_2, \dots, x_n$ and a query $x$, a relative-error quantile estimation algorithm can estimate the rank of…

Data Structures and Algorithms · Computer Science 2024-11-05 Elena Gribelyuk , Pachara Sawettamalya , Hongxun Wu , Huacheng Yu

We give near-optimal algorithms for computing an ellipsoidal rounding of a convex polytope whose vertices are given in a stream. The approximation factor is linear in the dimension (as in John's theorem) and only loses an excess logarithmic…

Data Structures and Algorithms · Computer Science 2023-11-17 Yury Makarychev , Naren Sarayu Manoj , Max Ovsiankin

Stellar streams are sensitive probes of the Galactic potential. The likelihood of a stream model given stream data is often assessed using simulations. However, comparing to simulations is challenging when even the stream paths can be hard…

Astrophysics of Galaxies · Physics 2023-05-03 Nathaniel Starkman , Jo Bovy , Jeremy J. Webb , Daniela Calvetti , Erkki Somersalo

The Whittle likelihood is a widely used and computationally efficient pseudo-likelihood. However, it is known to produce biased parameter estimates for large classes of models. We propose a method for de-biasing Whittle estimates for…

In the Gaia era it is increasingly apparent that traditional static, parameterized models are insufficient to describe the mass distribution of our complex, dynamically evolving Milky Way (MW). In this work, we compare different…

In this paper, we present a holistic view of the detection, characterization, and origin of stellar streams in the disk of a simulated Milky Way-like galaxy. The star-by-star simulation of the Galaxy evolves stars born in clusters in a…

Astrophysics of Galaxies · Physics 2021-06-07 Harshil Kamdar , Charlie Conroy , Yuan-Sen Ting

Many classical algorithms are known for computing the convex hull of a set of $n$ point in $\mathbb{R}^2$ using $O(n)$ space. For large point sets, whose size exceeds the size of the working space, these algorithms cannot be directly used.…

Computational Geometry · Computer Science 2018-10-02 Martin Farach-Colton , Meng Li , Meng-Tsung Tsai

According to the hierarchical formation paradigm, galaxies form through mergers of smaller entities and massive black holes (MBHs), if lurking at their centers, migrate to the nucleus of the newly formed galaxy, where they form binary…

Astrophysics of Galaxies · Physics 2024-09-25 Ludovica Varisco , Massimo Dotti , Matteo Bonetti , Elisa Bortolas , Alessandro Lupi

The Gaia mission has led to the discovery of over 100 stellar streams in the Milky Way, most of which likely originated from globular clusters (GCs). As the upcoming wide-field surveys can potentially continue to increase the number of…

Astrophysics of Galaxies · Physics 2025-12-12 Yingtian Chen , Oleg Y. Gnedin , Adrian M. Price-Whelan , Colin Holm-Hansen

We revisit the MaxSAT problem in the data stream model. In this problem, the stream consists of $m$ clauses that are disjunctions of literals drawn from $n$ Boolean variables. The objective is to find an assignment to the variables that…

Data Structures and Algorithms · Computer Science 2022-08-22 Hoa T. Vu

We use N-body simulations to model the tidal disruption of a star cluster in a Milky-Way-sized dark matter halo, which results in a narrow stream comparable to (but slightly wider than) Pal-5 or GD-1. The mean Galactic dark matter halo is…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Wai-Hin Wayne Ngan , Raymond G. Carlberg

I present a new framework for modeling the dynamics of tidal streams. The framework consists of simple models for the initial action-angle distribution of tidal debris, which can be straightforwardly evolved forward in time. Taking…

Astrophysics of Galaxies · Physics 2014-10-17 Jo Bovy

Real-world graphs often manifest as a massive temporal stream of edges. The need for real-time analysis of such large graph streams has led to progress on low memory, one-pass streaming graph algorithms. These algorithms were designed for…

Data Structures and Algorithms · Computer Science 2014-10-16 Madhav Jha , C. Seshadhri , Ali Pinar

The stellar velocity fields of elliptical galaxies hold clues to their dynamical structure and origin. The construction of velocity field models is greatly simplified by assuming an approximate geometrical form for the streamlines of the…

Astrophysics · Physics 2009-10-30 R. F. Anderson , Thomas S. Statler

A method for finding reduced-order approximations of turbulent flow models is presented. The method preserves bounds on the production of turbulent energy in the sense of the $\curly{L}_2$ norm of perturbations from a notional laminar…

Fluid Dynamics · Physics 2013-01-22 A S Sharma