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We introduce "Simulations Beyond The Local Universe" (SIBELIUS) that connect the Local Group to its cosmic environment. We show that introducing hierarchical small-scale perturbations to a density field constrained on large scales by…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-24 Till Sawala , Stuart McAlpine , Jens Jasche , Guilhem Lavaux , Adrian Jenkins , Peter H. Johansson , Carlos S. Frenk

Cosmological simulations are essential for inferring cosmological and galaxy population properties based on forward-modelling, but this typically requires finding the population of (sub)haloes and galaxies that they contain. The properties…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-04 Victor J. Forouhar Moreno , John Helly , Robert McGibbon , Joop Schaye , Matthieu Schaller , Jiaxin Han , Roi Kugel , Yannick M. Bahe

Aims. Several kinematic and chemical substructures have been recently found amongst Milky Way halo stars with retrograde motions. It is currently unclear how these various structures are related to each other. This Letter aims to shed light…

Astrophysics of Galaxies · Physics 2019-11-13 Helmer H. Koppelman , Amina Helmi , Davide Massari , Adrian M. Price-Whelan , Tjitske K. Starkenburg

The early universe hosted a large population of low-mass virialized "minihalos," that were not massive enough to form stars on their own. While most minihalos were photoevaporated by ionizing photons from star-forming galaxies, these…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 William J Gray , Evan Scannapieco

Astrophysical observations spanning dwarf galaxies to galaxy clusters indicate that dark matter (DM) halos are less dense in their central regions compared to expectations from collisionless DM N-body simulations. Using detailed fits to DM…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-03 Manoj Kaplinghat , Sean Tulin , Hai-Bo Yu

In this work an ensemble of simulated Local Group analogues is used to constrain the properties of the mass assembly history of the Milky Way (MW) and Andromeda (M31) galaxies. These objects have been obtained using the constrained…

We present an analysis of the distribution of structural properties for Milky Way-mass halos in the Millennium-II Simulation (MS-II). This simulation of structure formation within the standard LCDM cosmology contains thousands of Milky…

Cosmology and Nongalactic Astrophysics · Physics 2010-07-21 Michael Boylan-Kolchin , Volker Springel , Simon D. M. White , Adrian Jenkins

The halo of the Milky Way has long been hypothesized to harbour significant amounts of merger debris. This view has been supported over more than a decade by wide-field photometric surveys which have revealed the outer halo to be lumpy. The…

Astrophysics of Galaxies · Physics 2019-05-01 Helmer H. Koppelman , Amina Helmi , Davide Massari , Sebastian Roelenga , Ulrich Bastian

Using a dark matter only Constrained Local UniversE Simulation (CLUES) we examine the existence of subhaloes that change their affiliation from one of the two prominent hosts in the Local Group (i.e. the Milky Way and the Andromeda galaxy)…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Alexander Knebe , Noam I Libeskind , Timur Doumler , Gustavo Yepes , Stefan Gottloeber , Yehuda Hoffman

In two recent papers, we developed a powerful technique to link the distribution of galaxies to that of dark matter haloes by considering halo occupation numbers as function of galaxy luminosity and type. In this paper we use these…

Astrophysics · Physics 2009-11-07 Xiaohu Yang , H. J. Mo , Y. P. Jing , Frank C. van den Bosch , YaoQuan Chu

If dark matter has a large self-interaction scattering cross section, then interactions among dark-matter particles will drive galaxy and cluster halos to become spherical in their centers. Work in the past has used this effect to rule out…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Annika H. G. Peter , Miguel Rocha , James S. Bullock , Manoj Kaplinghat

We present a publicly available catalogue of massive structures in the nearby Universe, constructed from the Manticore-Local posterior ensemble, a Bayesian field-level reconstruction that infers the underlying dark matter distribution from…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-24 Stuart McAlpine

As galaxies form hierarchically, larger satellites may accrete alongside smaller companions in group infall events. This coordinated accretion is likely to have left signatures in the Milky Way's stellar halo at the present day. Our goal is…

Astrophysics of Galaxies · Physics 2025-08-20 Thomas M. Callingham , Amina Helmi

A study of the group properties of galaxies in our immediate neighborhood provides a singular opportunity to observationally constrain the halo mass function, a fundamental characterization of galaxy formation. Detailed studies of…

Astrophysics of Galaxies · Physics 2017-07-13 Ehsan Kourkchi , R. Brent Tully

Results are presented from a wide area, high resolution HI synthesis survey of the outer regions of the nearby M81 group, where internal (galactic) and external (group-related) evolution processes can be studied simultaneously in great…

Astrophysics · Physics 2007-05-23 M. Bureau , F. Walter , J. van Gorkom , C. Carignan

While hard-sphere models form the foundation of theoretical condensed matter physics, real systems often exhibit some degree of softness. We present a theoretical and numerical study of a class of nearly hard-sphere systems, generalized…

Soft Condensed Matter · Physics 2025-07-22 Ulf R. Pedersen

The connection between dark matter halos and galactic baryons is often not well-constrained nor well-resolved in cosmological hydrodynamical simulations. Thus, Halo Occupation Distribution (HOD) models that assign galaxies to halos based on…

Astrophysics of Galaxies · Physics 2015-10-21 Stephanie Tonnesen , Renyue Cen

Context: Several observations of the local Universe (LU) point towards the existence of very prominent structures. The presence of massive galaxy clusters and local super clusters on the one hand, but also large local voids and…

We study the impact of numerical parameters on the properties of cold dark matter haloes formed in collisionless cosmological simulations. We quantify convergence in the median spherically-averaged circular velocity profiles for haloes of…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-12 Aaron D. Ludlow , Joop Schaye , Richard Bower

We give a summary of recent results on spatial and velocity biases in cosmological models. Progress in numerical techniques made it possible to simulate halos in large volumes with a such accuracy that halos survive in dense environments of…

Astrophysics · Physics 2007-05-23 Anatoly Klypin