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Obtaining a census of dark matter structures at low mass ($\leq 10^9 M_\odot$) can provide strong constraints on the nature of dark matter, though identifying such structures remains difficult. In this work, we study the galaxy cluster RX…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-26 David J. Lagattuta , Mathilde Jauzac , Jessica E. Doppel , Guillaume Mahler , Anna Niemiec

The predicted abundance and properties of the low-mass substructures embedded inside larger dark matter haloes differ sharply among alternative dark matter models. Too small to host galaxies themselves, these subhaloes may still be detected…

We developed a new method to extract halo merger rates from the Millennium Simulation. First, by removing superfluous mergers that are artifacts of the FOF halo finder, we find a lower merger rate compared to previous work. The reductions…

Astrophysics · Physics 2010-11-02 S. Genel , R. Genzel , N. Bouché , T. Naab , A. Sternberg

We use explainable neural networks to connect the evolutionary history of dark matter halos with their density profiles. The network captures independent factors of variation in the density profiles within a low-dimensional representation,…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-22 Luisa Lucie-Smith , Hiranya V. Peiris , Andrew Pontzen

We present a detailed description and validation of our massively-parallel update to the mass-Peak Patch method, a fully predictive initial-space algorithm to quickly generate dark matter halo catalogues in very large cosmological volumes.…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-05 George Stein , Marcelo A. Alvarez , J. Richard Bond

Measuring the density profile and mass concentration of dark-matter haloes is a key test of the standard cold dark matter paradigm. Such objects are dark and thus challenging to characterise, but they can be studied via gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-07 S. Vegetti , S. D. M. White , J. P. McKean , D. M. Powell , C. Spingola , D. Massari , G. Despali , C. D. Fassnacht

We present accurate measurements of the linear, quadratic, and cubic local bias of dark matter halos, using curved "separate universe" N-body simulations which effectively incorporate an infinite-wavelength overdensity. This can be seen as…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-15 Titouan Lazeyras , Christian Wagner , Tobias Baldauf , Fabian Schmidt

Understanding the impact of halo properties beyond halo mass on the clustering of galaxies (namely galaxy assembly bias) remains a challenge for contemporary models of galaxy clustering. We explore the use of machine learning to predict the…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-15 Xiaoju Xu , Saurabh Kumar , Idit Zehavi , Sergio Contreras

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

We describe a model of dark matter halo abundances and clustering which combines the two most widely used approaches to this problem: that based on peaks and the other based on excursion sets. Our approach can be thought of as addressing…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Aseem Paranjape , Ravi K. Sheth

The annihilation of dark matter (DM) particles is expected to produce Standard Model particles, providing a potential indirect signature of DM. The clumpy substructure of DM haloes amplifies the expected annihilation signal, an effect…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-30 Feven Markos Hunde , Wojciech A. Hellwing , Maciej Bilicki

We study the relationship between dark-matter haloes and matter in the MIP $N$-body simulation ensemble, which allows precision measurements of this relationship, even deeply into voids. What enables this is a lack of discreteness,…

Cosmology and Nongalactic Astrophysics · Physics 2014-05-06 Mark C. Neyrinck , Miguel A. Aragon-Calvo , Donghui Jeong , Xin Wang

Strong gravitational lensing is a powerful tool for probing the matter distribution in the cores of massive dark matter haloes. Recent and ongoing analyses of galaxy cluster surveys (MACS, CFHTLS, SDSS, SGAS, CLASH, LoCuSS) have adressed…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-17 Carlo Giocoli , Massimo Meneghetti , Matthias Bartelmann , Lauro Moscardini , Michele Boldrin

In this paper, we propose a method for density-based clustering in high-dimensional spaces that combines Locality-Sensitive Hashing (LSH) with the Quick Shift algorithm. The Quick Shift algorithm, known for its hierarchical clustering…

Machine Learning · Computer Science 2025-12-01 Sajjad Hashemian

This paper focuses on density-based clustering, particularly the Density Peak (DP) algorithm and the one based on density-connectivity DBSCAN; and proposes a new method which takes advantage of the individual strengths of these two methods…

Machine Learning · Computer Science 2024-01-30 Ye Zhu , Kai Ming Ting , Yuan Jin , Maia Angelova

We apply a novel method with machine learning to calibrate sub-grid models within numerical simulation codes to achieve convergence with observations and between different codes. It utilizes active learning and neural density estimators.…

Astrophysics of Galaxies · Physics 2022-10-07 Boon Kiat Oh , Hongjun An , Eun-jin Shin , Ji-hoon Kim , Sungwook E. Hong

A density based hierarchical group-finding algorithm is used to identify stellar halo structures in a catalog of M-giants from the Two Micron All Sky Survey (2MASS). The intrinsic brightness of M-giant stars means that this catalog probes…

This work presents advancements in model-agnostic searches for new physics at the Large Hadron Collider (LHC) through the application of event-based anomaly detection techniques utilizing unsupervised machine learning. We discuss the…

High Energy Physics - Phenomenology · Physics 2025-12-01 Wasikul Islam , Sergei Chekanov , Nicholas Luongo

We present observations of a new group of structures in the diffuse Galactic ISM: slender, linear HI features we dub "fibers" that extend for many degrees at high Galactic latitude. To characterize and measure the extent and strength of…

Astrophysics of Galaxies · Physics 2014-06-19 S E Clark , J E G Peek , M E Putman

The Kilo-Degree Survey (KiDS) is an optical wide-field survey designed to map the matter distribution in the Universe using weak gravitational lensing. In this paper, we use these data to measure the density profiles and masses of a sample…

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