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We present a method to numerically estimate the densities of a discretely sampled data based on binary space partitioning tree. We start with a root node containing all the particles and then recursively divide each node into two nodes each…

Astrophysics · Physics 2015-06-24 Sanjib Sharma , Matthias Steinmetz

The role of baryonic physics, star formation, and stellar feedback, in shaping the galaxies and their host halos is an evolving topic. The dark matter aspects are illustrated in this work by showing distribution features in a…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-10 A. Núñez-Castiñeyra , E. Nezri , P. Mollitor , J. Devriendt , R. Teyssier

Aims. We present an analysis of 37 high-quality extended rotation curves that highlights the existence of a new discrepancy (or a new aspect of an old discrepancy) between the density profiles predicted by the Lambda Cold Dark Matter…

Astrophysics · Physics 2008-11-26 Gianfranco Gentile , Chiara Tonini , Paolo Salucci

(Abridged) The analysis of the rotation curves (RCs) of spiral galaxies provides an efficient diagnostic for studying the properties of dark matter halos and their relations with the baryonic material. We have modeled the RCs of galaxies…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-21 Laurent Chemin , W. J. G. de Blok , Gary A. Mamon

We present the results of a series of cosmological $N$-body simulations of a Vector Dark Energy (VDE) model, performed using a suitably modified version of the publicly available \texttt{GADGET}-2 code. The setups of our simulations were…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Edoardo Carlesi , Alexander Knebe , Gustavo Yepes , Stefan Gottloeber , Jose Beltran Jimenez , Antonio L. Maroto

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

A method is presented for computing the 6-D phase-space density f(x,v) and its PDF v(f) in an N-body system. It is based on Delaunay tessellation, yielding v(f) with a fixed smoothing window over a wide f range, independent of the sampling…

Astrophysics · Physics 2007-05-23 Avishai Dekel , Itai Arad

We present new constraints on the density profiles of dark matter (DM) halos in seven nearby dwarf galaxies from measurements of their integrated stellar light and gas kinematics. The gas kinematics of low mass galaxies frequently suggest…

The size distributions of 2D and 3D Voronoi cells and of cells of $V_p(2,3)$,--2D cut of 3D Voronoi diagram--are explored, with the single-parameter (re-scaled) gamma distribution playing a central role in the analytical fitting.…

Astrophysics · Physics 2011-09-20 Lorenzo Zaninetti

We measure the redshift space reduced void probability function (VPF) for 2dFGRS volume limited galaxy samples covering the absolute magnitude range M_bJ-5logh=-18 to -22. Theoretically, the VPF connects the distribution of voids to the…

We stress the importance of stochastic geometry as a branch of mathematical statistics particularly suited to model and investigate nontrivial spatial patterns. One of its key concepts, Voronoi tessellations, represents a versatile and…

Astrophysics · Physics 2007-05-23 Rien van de Weygaert

Context. The Vista Variables in the Via Lactea (VVV) near-infrared variability survey explores some of the most complex regions of the Milky Way bulge and disk in terms of high extinction and high crowding. Aims. We add a new wavelength…

We study the formation of dark matter halos in the concordance LCDM model over a wide range of redshifts, from z=20 to the present. Our primary focus is the halo mass function, a key probe of cosmology. By performing a large suite of…

Astrophysics · Physics 2008-11-26 Zarija Lukic , Katrin Heitmann , Salman Habib , Sergei Bashinsky , Paul M. Ricker

Dark matter-dominated cluster-scale halos act as an important cosmological probe and provide a key testing ground for structure formation theory. Focusing on their mass profiles, we have carried out (gravity-only) simulations of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Suman Bhattacharya , Salman Habib , Katrin Heitmann , Alexey Vikhlinin

We utilize the Magneticum suite of hydrodynamical simulations to investigate the formation and evolution of cosmic voids from $z = 5.04$ to present day, using cold dark matter and (sub-) halo tracers in high-density samples. This includes…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-10 Nico Schuster , Nico Hamaus , Alice Pisani , Klaus Dolag , Jochen Weller

A large number of observations have shown that the dark matter halo surface density, given by the product of halo core radius and core density is nearly constant for a diverse suite of galaxies. Although this invariance of the halo surface…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-29 Gopika K. , Shantanu Desai , Aseem Paranjape

Local-type primordial non-gaussianity generates a distinctive term in the clustering of tracers of large-scale structure, behaving as $k^{-2}$ at small wavenumbers $k$. In order to use this signal in a sample of galaxies to measure the…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-28 Neal Dalal , Will J. Percival

We use measurements of the projected galaxy correlation function w_p and galaxy void statistics to test whether the galaxy content of halos of fixed mass is systematically different in low density environments. We present new measurements…

The survey volume of a proper motion-limited sample is typically much smaller than a magnitude-limited sample. This is because of the noisy astrometric measurements from detectors that are not dedicated for astrometric missions. In order to…

Instrumentation and Methods for Astrophysics · Physics 2017-05-01 Marco C. Lam

Distribution of galaxies may be a biased tracer of the dark matter distribution and the relation between the galaxies and the total mass may be stochastic, non-linear and time-dependent. Since many observations of galaxy clustering will be…

Astrophysics · Physics 2009-10-31 Atsushi Taruya