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Mysterious dark matter constitutes about 85% of all mass in the Universe. Clustering of dark matter plays the dominant role in the formation of all observed structures on scales from a fraction to a few hundreds of Mega-parsecs. Galaxies…

Cosmology and Nongalactic Astrophysics · Physics 2017-07-26 Nesar S. Ramachandra , Sergei F. Shandarin

Identifying galaxies in hydrodynamical simulations is a difficult task, particularly in regions of high density such as galaxy groups and clusters. We present a new scale-free shape-independent algorithm to robustly and accurately identify…

We use N-body simulations to investigate the structure of dark halos in the standard Cold Dark Matter cosmogony. Halos are excised from simulations of cosmologically representative regions and are resimulated individually at high…

Astrophysics · Physics 2008-11-26 Julio F. Navarro , Carlos S. Frenk , Simon D. M. White

The formation and structure of dark matter halos is studied by constrained simulations. A series of experiments of the formation of a 10^12 Msun/h halo is designed to study the dependence of the density profile on its merging history. We…

The dark matter halo mass function is a key repository of cosmological information over a wide range of mass scales, from individual galaxies to galaxy clusters. N-body simulations have established that the friends-of-friends (FOF) mass…

Astrophysics · Physics 2009-06-23 Zarija Lukić , Darren Reed , Salman Habib , Katrin Heitmann

We investigate how galactic disk structures connect to the detailed properties of their host dark-matter halos using the TNG50 simulation. From the hydrodynamic and matched dark-matter-only runs, we measure a comprehensive list of halo…

Astrophysics of Galaxies · Physics 2026-03-20 Jinning Liang , Fangzhou Jiang , Houjun Mo , Andrew Benson , Philip F. Hopkins , Avishal Dekel , Luis C. Ho

Cosmological N-body simulations have long suggested that the pseudo phase-space density (PPSD), $\rho/\sigma^3$, of cold dark matter haloes follows the universal relation $\rho/\sigma^3 \propto r^{\chi}$, with $\chi \approx -1.875$, as…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-15 Bocheng Feng , Ethan O. Nadler , S. Peng Oh , Suoqing Ji

In this work, we expand and test the capabilities of our recently developed super-resolution (SR) model to generate high-resolution (HR) realizations of the full phase-space matter distribution, including both displacement and velocity,…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-20 Yueying Ni , Yin Li , Patrick Lachance , Rupert A. C. Croft , Tiziana Di Matteo , Simeon Bird , Yu Feng

We introduce a new method based on nonnegative matrix factorization, Neural NMF, for detecting latent hierarchical structure in data. Datasets with hierarchical structure arise in a wide variety of fields, such as document classification,…

Machine Learning · Computer Science 2023-03-02 Tyler Will , Runyu Zhang , Eli Sadovnik , Mengdi Gao , Joshua Vendrow , Jamie Haddock , Denali Molitor , Deanna Needell

We develop an analysis pipeline for characterizing the topology of large scale structure and extracting cosmological constraints based on persistent homology. Persistent homology is a technique from topological data analysis that quantifies…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-14 Matteo Biagetti , Alex Cole , Gary Shiu

Cosmological structure formation predicts that our galactic halo contains an enormous hierarchy of substructures and streams, the remnants of the merging hierarchy that began with tiny Earth mass microhalos. If these structures persist…

Astrophysics of Galaxies · Physics 2015-03-19 Aurel Schneider , Lawrence M. Krauss , Ben Moore

Cosmic voids provide a powerful probe of the origin and evolution of structures in the Universe because their dynamics can remain near-linear to the present day. As a result they have the potential to connect large scale structure at late…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-26 Stephen Stopyra , Hiranya V. Peiris , Andrew Pontzen

Generating mocks for future sky surveys requires large volumes and high resolutions, which is computationally expensive even for fast simulations. In this work we try to develop numerical schemes to calibrate various halo and matter…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-15 Biwei Dai , Yu Feng , Uros Seljak , Sukhdeep Singh

The evolution of the phase-space density profile in dark matter (DM) halos is investigated by means of constrained simulations, designed to control the merging history of a given DM halo. Halos evolve through a series of quiescent phases of…

Astrophysics · Physics 2009-11-13 Yehuda Hoffman , Emilio Romano-Diaz , Isaac Shlosman , Clayton Heller

In three previous Papers we analysed the origin of the properties of halo substructure found in simulations. This was achieved by deriving them analytically in the peak model of structure formation, using the statistics of nested peaks…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-17 Eduard Salvador-Solé , Alberto Manrique , Andreu Rocamora

We present a new high-resolution N-body algorithm for cosmological simulations. The algorithm employs a traditional particle-mesh technique on a cubic grid and successive multilevel relaxations on the finer meshes, introduced recursively in…

Astrophysics · Physics 2009-10-30 Andrey V. Kravtsov , Anatoly A. Klypin , Alexei M. Khokhlov

Various laboratory-based experiments are underway attempting to detect dark matter directly. The event rates and detailed signals expected in these experiments depend on the dark matter phase space distribution on sub-milliparsec scales.…

Astrophysics · Physics 2011-08-31 Daniele S. M. Fantin , Michael R. Merrifield , Anne M. Green

While various codes exist to systematically and robustly find haloes and subhaloes in cosmological simulations (Knebe et al., 2011, Onions et al., 2012), this is the first work to introduce and rigorously test codes that find tidal debris…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Pascal J. Elahi , Jiaxin Han , Hanni Lux , Yago Ascasibar , Peter Behroozi , Alexander Knebe , Stuart I. Muldrew , Julian Onions , Frazer Pearce

Three halo finder algorithms - hierarchical friends-of-friends, bound density maxima, and 6D minimum spanning tree - are discussed.

Astrophysics · Physics 2007-05-23 S. Gottloeber

We present a framework for the hierarchical identification and characterization of voids based on the Watershed Void Finder. The Hierarchical Void Finder is based on a generalization of the scale space of a density field invoked in order to…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 M. A. Aragon-Calvo , R. van de Weygaert , P. Araya-Melo , E. Platen , A. S. Szalay