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We use the semi-analytical approach to analyze gravitational lensing of quasars by dark halos in various cold dark matter (CDM) cosmologies, in order to determine the sensitivity of the prediction probabilities of images separations to the…

Astrophysics · Physics 2009-10-31 Li-Xin Li , Jeremiah P. Ostriker

An ambitious goal in cosmology is to forward-model the observed distribution of galaxies in the nearby Universe today from the initial conditions of large-scale structures. For practical reasons, the spatial resolution at which this can be…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-18 Tom Charnock , Guilhem Lavaux , Benjamin D. Wandelt , Supranta Sarma Boruah , Jens Jasche , Michael J. Hudson

The friends-of-friends algorithm (hereafter, FOF) is a percolation algorithm which is routinely used to identify dark matter halos from N-body simulations. We use results from percolation theory to show that the boundary of FOF halos does…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Surhud More , Andrey Kravtsov , Neal Dalal , Stefan Gottlöber

We generate stellar distribution functions (DFs) in triaxial haloes in order to examine the reliability of slopes $\Gamma\equiv \Delta {\rm log} M / \Delta {\rm log} r$ inferred by applying mass estimators of the form $M\propto R_e\sigma^2$…

Astrophysics of Galaxies · Physics 2015-06-15 Chervin F. P. Laporte , Matthew G. Walker , Jorge Peñarrubia

The statistics of gravitational lensing can provide us with a very powerful probe of the mass distribution of matter in the universe. By comparing predicted strong lensing probabilities with observations, we can test the mass distribution…

Astrophysics · Physics 2009-11-10 Tong-Jie Zhang

Non-Gaussianities of dynamical origin are disentangled from primordial ones using the formalism of large deviation statistics with spherical collapse dynamics. This is achieved by relying on accurate analytical predictions for the one-point…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-27 Cora Uhlemann , Enrico Pajer , Christophe Pichon , Takahiro Nishimichi , Sandrine Codis , Francis Bernardeau

The properties of the probability distribution function of the cosmological continuous density field are studied. We present further developments and compare dynamically motivated methods to derive the PDF. One of them is based on the…

Astrophysics · Physics 2009-10-22 F. Bernardeau , L. Kofman

Understanding the nature of dark matter is among the top priorities of modern physics. However, due to its inertness, detecting and studying it directly in terrestrial experiments is extremely challenging. Numerical N-body simulations…

Astrophysics of Galaxies · Physics 2024-03-06 Zhen Li , Steen H. Hansen

We use a suite of 3D simulations of star-forming molecular clouds, with and without stellar feedback and magnetic fields, to investigate the effectiveness of different fitting methods for volume and column density probability distribution…

Astrophysics of Galaxies · Physics 2023-05-22 Avery Kiihne , Sabrina M. Appel , Blakesley Burkhart , Vadim A. Semenov , Christoph Federrath

We develop a novel method of measuring the lensing distortion profiles of clusters with stacking the scaled amplitudes of background galaxy ellipticities as a function of the scaled centric radius according to the NFW prediction of each…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-21 Hiroko Niikura , Masahiro Takada , Nobuhiro Okabe , Rossella Martino , Ryuichi Takahashi

Using the GAEA semi-analytic model, we analyse the connection between Damped Lyman-$\alpha$ systems (DLAs) and HI in galaxies. Our state-of-the-art semi-analytic model is tuned to reproduce the local galaxy HI mass function, and that also…

Astrophysics of Galaxies · Physics 2020-08-12 Serafina Di Gioia , Stefano Cristiani , Gabriella De Lucia , Lizhi Xie

Simulations are expected to be the powerful tool to investigate the baryon effects on dark matter (DM) halos. Recent high resolution, cosmological hydrodynamic simulations (\citealt{Cintio14}, DC14) predict that the inner density profiles…

Astrophysics of Galaxies · Physics 2017-08-09 Lin Wang , Da-Ming Chen , Ran Li

We develop an analytical framework to predict the one-point probability distribution function (PDF) of dispersion measures (DMs) for fast radio bursts (FRBs) within the baryonification (BFC) model. BFC provides a computationally efficient…

N-body simulations of dark matter halos show that the density profiles of halos behave as $\rho(r)\propto r^{-\alpha(r)}$, where the density logarithmic slope $\alpha \simeq 1\sim1.5$ in the center and $\alpha \simeq 3\sim 4$ in the outer…

Astrophysics · Physics 2015-05-13 Ding Ma , Ping He

Dark matter-only simulations predict that dark matter halos have steep, cuspy inner density profiles, while observations of dwarf galaxies find a range of inner slopes that are often much shallower. There is debate whether this discrepancy…

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

We examine the effects of mass resolution and force softening on the density profiles of cold dark matter halos that form within cosmological N-body simulations. As we increase the mass and force resolution, we resolve progenitor halos that…

Astrophysics · Physics 2009-10-30 Ben Moore , Fabio Governato , Tom Quinn , Joachim Stadel , George Lake

Using an analytic model calibrated against numerical simulations, we calculate the central densities of dark matter halos in a ``conventional'' cold dark matter model with a cosmological constant (LCDM) and in a ``tilted'' model (TLCDM)…

Astrophysics · Physics 2007-05-23 S. M. Khairul Alam , James S. Bullock , David H. Weinberg

We study the differential energy distribution of dark matter halos, carrying out cosmological N-body simulation.We give an analytical formula of the differential energy distribution of dark matter in the halos obtained by the numerical…

Astrophysics · Physics 2009-10-31 Chiaki Hanyu , Asao Habe

We investigate the effect of primordial non-Gaussianities on halo number counts using N-body simulations with different values of $f_{\rm NL}^{\rm loc}$. We show how current theoretical models fail to adequately describe the non-Gaussian…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-30 Luca Fiorino , Sofia Contarini , Federico Marulli , Ariel G. Sanchez , Marco Baldi , Andrea Fiorilli , Lauro Moscardini