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We report a series of high-resolution cosmological N-body simulations designed to explore the formation and properties of dark matter halos with masses close to the damping scale of the primordial power spectrum of density fluctuations. We…

Astrophysics · Physics 2009-11-13 P. Colin , O. Valenzuela , V. Avila-Reese

We introduce a new self-consistent structure finding algorithm that parses large scale cosmological structure into clusters, filaments and voids. This structure finding algorithm probes the cosmological structure at multiple scales and…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-04 Ali Snedden , Lara Arielle Phillips , Grant J. Mathews , Jared Coughlin , In-Saeng Suh , Aparna Bhattacharya

The spectrum of cold dark matter particles on Earth is expected to have peaks in velocity space associated with particles which are falling onto the Galaxy for the first time and with particles which have fallen in and out of the Galaxy…

Astrophysics · Physics 2010-11-30 P. Sikivie , I. I. Tkachev , Yun Wang

Hash codes are a very efficient data representation needed to be able to cope with the ever growing amounts of data. We introduce a random forest semantic hashing scheme with information-theoretic code aggregation, showing for the first…

Computer Vision and Pattern Recognition · Computer Science 2015-04-20 Qiang Qiu , Guillermo Sapiro , Alex Bronstein

Shape estimates that quantify the halo anisotropic mass distribution are valuable parameters that provide information on their assembly process and evolution. Measurements of the mean shapes for a sample of cluster-sized halos can be used…

The wealth of data being gathered about humans and their surroundings drives new machine learning applications in various fields. Consequently, more and more often, classifiers are trained using not only numerical data but also complex data…

Machine Learning · Computer Science 2022-04-13 Maciej Piernik , Dariusz Brzezinski , Pawel Zawadzki

We introduce a new method to calculate dark matter halo density profiles from simulations. Each particle is 'smeared' over its orbit to obtain a dynamical profile that is averaged over a dynamical time, in contrast to the traditional…

Astrophysics of Galaxies · Physics 2024-01-26 Claudia Muni , Andrew Pontzen , Jason L. Sanders , Martin P. Rey , Justin I. Read , Oscar Agertz

Cold dark matter (CDM) could be composed of primordial black holes (PBH) in addition to or instead of more orthodox weakly interacting massive particle dark matter (PDM). We study the formation of the first structures in such $\Lambda$PBH…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-23 Derek Inman , Yacine Ali-Haïmoud

Using cosmological dark matter only simulations of a $(1.6$ Gpc$/h)^3$ volume from the Legacy simulation project, we calculate Cosmic Mach Numbers (CMN) and perform a theoretical investigation of their relation with halo properties and…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-09 Romain Meriot , Sadegh Khochfar , Jose Onorbe , Britton Smith

Precise cosmic web classification of observed galaxies in massive spectroscopic surveys can be either highly uncertain or computationally expensive. As an alternative, we explore a fast Machine Learning-based approach to infer the…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-08 John F. Suárez-Pérez , Yeimy Camargo , Xiao-Dong Li , Jaime E. Forero-Romero

We present a new algorithm (PINOCCHIO, PINpointing Orbit-Crossing Collapsed HIerarchical objects) to predict accurately the formation and evolution of individual dark matter haloes in a given realization of an initial linear density field.…

Astrophysics · Physics 2009-11-07 P. Monaco , T. Theuns , G. Taffoni , F. Governato , T. Quinn , J. Stadel

We study the reliability of dark-matter halo detections with three different linear filters applied to weak-lensing data. We use ray-tracing in the multiple lens-plane approximation through a large cosmological simulation to construct…

Predicting the spatial distribution of objects as a function of cosmology is an essential ingredient for the exploitation of future galaxy surveys. In this paper we show that a specially-designed suite of gravity-only simulations together…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-28 S. Contreras , R. E. Angulo , M. Zennaro , G. Aricó , M. Pellejero-Ibañez

We propose a method to generate `genetically-modified' (GM) initial conditions for high-resolution simulations of galaxy formation in a cosmological context. Building on the Hoffman-Ribak algorithm, we start from a reference simulation with…

Astrophysics of Galaxies · Physics 2016-01-29 Nina Roth , Andrew Pontzen , Hiranya V. Peiris

We revisit techniques for performing cosmological simulations with both baryons and cold dark matter when each fluid has different initial conditions, as is the case at the end of the radiation era. Most simulations do not reproduce the…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-17 Simeon Bird , Yu Feng , Christian Pedersen , Andreu Font-Ribera

In the standard cosmological model a mysterious cold dark matter (CDM) component dominates the formation of structures. Numerical studies of the formation of CDM halos have produced several robust results that allow unique tests of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Jürg Diemand , Ben Moore

We present and test a method for modifying the catalogue of dark matter haloes produced from a given cosmological simulation, so that it resembles the result of a simulation with an entirely different set of parameters. This extends the…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-02 Alexander Mead , John Peacock

We present a new cosmological probe for galaxy clusters, the halo sparsity. This characterises halos in terms of the ratio of halo masses measured at two different radii and carries cosmological information encoded in the halo mass profile.…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-08 P. S. Corasaniti , S. Ettori , Y. Rasera , M. Sereno , S. Amodeo , M. -A. Breton , V. Ghirardini , D. Eckert

We systematically study the effects of varying the starting redshift z_i for cosmological simulations in the highly non-linear regime. Our primary focus lies with the (individual) properties of dark matter halos -- namely the mass, spin,…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-11 Alexander Knebe , Christian Wagner , Steffen Knollmann , Tobias Diekershoff , Fabian Krause

The simple, conventional dark matter halo mass definitions commonly used in cosmological simulations ("virial" mass, FoF mass, $M_{50,100,200,...}$) only capture part of the collapsed material and are therefore inconsistent with the halo…

Cosmology and Nongalactic Astrophysics · Physics 2011-11-14 Donnino Anderhalden , Juerg Diemand