scholarly journals The Cosmological Mass Distribution Function in the Zeldovich Approximation

1998 ◽  
Vol 500 (1) ◽  
pp. 14-27 ◽  
Author(s):  
Jounghun Lee ◽  
Sergei F. Shandarin
Keyword(s):  
Distribution Function ◽  
Mass Distribution ◽  
Mass Distribution Function

The mass distribution function of groups of galaxies

1992 ◽  
Vol 389 ◽  
pp. 68 ◽  
Author(s):  
A. Pisani ◽  
G. Giuricin ◽  
F. Mardirossian ◽  
M. Mezzetti
Keyword(s):  
Distribution Function ◽  
Mass Distribution ◽  
Groups Of Galaxies ◽  
Mass Distribution Function

scholarly journals Neural physical engines for inferring the halo mass distribution function

2020 ◽  
Vol 494 (1) ◽  
pp. 50-61 ◽  
Author(s):  
Tom Charnock ◽  
Guilhem Lavaux ◽  
Benjamin D Wandelt ◽  
Supranta Sarma Boruah ◽  
Jens Jasche ◽  
...  
Keyword(s):  
Dark Matter ◽  
Distribution Function ◽  
Mass Distribution ◽  
Large Scale ◽  
Initial Conditions ◽  
Matter Density ◽  
Practical Reasons ◽  
Dark Matter Density ◽  
Bias Model ◽  
Mass Distribution Function

ABSTRACT 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 done is necessarily limited. Consequently, one needs a mapping between the density of dark matter averaged over ∼Mpc scales and the distribution of dark matter haloes (used as a proxy for galaxies) in the same region. Here, we demonstrate a method for determining the halo mass distribution function by learning the tracer bias between density fields and halo catalogues using a neural bias model. The method is based on the Bayesian analysis of simple, physically motivated, neural network-like architectures, which we denote as neural physical engines, and neural density estimation. As a result, we are able to sample the initial phases of the dark matter density field while inferring the parameters describing the halo mass distribution function, providing a fully Bayesian interpretation of both the initial dark matter density distribution and the neural bias model. We successfully run an upgraded borg (Bayesian Origin Reconstruction from Galaxies) inference using our new likelihood and neural bias model with halo catalogues derived from full N-body simulations. In preliminary results, we notice there could potentially be orders of magnitude improvement in modelling compared to classical biasing techniques.

scholarly journals 4. Factors affecting radar-meteor echo durations

1968 ◽  
Vol 33 ◽  
pp. 45-49
Author(s):  
A. Hajduk
Keyword(s):  
Distribution Function ◽  
Mass Distribution ◽  
Meteor Shower ◽  
Time Intervals ◽  
Factors Affecting ◽  
Factors Influencing ◽  
Two Factors ◽  
The Mean ◽  
Mass Distribution Function ◽  
Radar Meteor

The analysis of two factors influencing radar-meteor echo durations leads to the conclusion, that (1) the echo duration depends considerably on the train position with respect to the sensitivity contours of the radar; (2) the mean echo duration changes with respect to the radiant motion of a meteor shower. As a consequence of the factors mentioned above, the magnitude function, or the mass distribution function depends significantly on the observational conditions, as well as on the choice of the range and time intervals of the investigated sample.

Analytical Approach to the Mass Distribution Function of Subhalos and Cold Fronts in Galaxy Clusters

2002 ◽  
Vol 577 (1) ◽  
pp. 11-21 ◽  
Author(s):  
Yutaka Fujita ◽  
Craig L. Sarazin ◽  
Masahiro Nagashima ◽  
Taihei Yano
Keyword(s):  
Distribution Function ◽  
Galaxy Clusters ◽  
Mass Distribution ◽  
Analytical Approach ◽  
Cold Fronts ◽  
Mass Distribution Function

scholarly journals The AGN–galaxy–halo connection: The distribution of AGN host halo masses to z = 2.5

2021 ◽  
Author(s):  
James Aird ◽  
Alison L Coil
Keyword(s):  
Dark Matter ◽  
Distribution Function ◽  
Mass Distribution ◽  
Accretion Rate ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
Galaxy Halo ◽  
Halo Masses ◽  
Mass Distribution Function

Abstract It is widely reported, based on clustering measurements of observed active galactic nuclei (AGN) samples, that AGN reside in similar mass host dark matter halos across the bulk of cosmic time, with log $\mathcal {M}/\mathcal {M}_{\odot }\sim 12.5-13.0$ to z ∼ 2.5. We show that this is due in part to the AGN fraction in galaxies rising with increasing stellar mass, combined with AGN observational selection effects that exacerbate this trend. Here, we use AGN specific accretion rate distribution functions determined as a function of stellar mass and redshift for star-forming and quiescent galaxies separately, combined with the latest galaxy-halo connection models, to determine the parent and sub-halo mass distribution function of AGN to various observational limits. We find that while the median (sub-)halo mass of AGN, $\approx 10^{12}\mathcal {M}_{\odot }$, is fairly constant with luminosity, specific accretion rate, and redshift, the full halo mass distribution function is broad, spanning several orders of magnitude. We show that widely used methods to infer a typical dark matter halo mass based on an observed AGN clustering amplitude can result in biased, systematically high host halo masses. While the AGN satellite fraction rises with increasing parent halo mass, we find that the central galaxy is often not an AGN. Our results elucidate the physical causes for the apparent uniformity of AGN host halos across cosmic time and underscore the importance of accounting for AGN selection biases when interpreting observational AGN clustering results. We further show that AGN clustering is most easily interpreted in terms of the relative bias to galaxy samples, not from absolute bias measurements alone.

scholarly journals GEODYNAMICS

GEODYNAMICS ◽  
2021 ◽  
Vol 2(31)2021 (2(31)) ◽  
pp. 29-40
Author(s):  
Mykhailo Fys ◽  
◽  
Andrii Brydun ◽  
Mariana Yurkiv ◽  
Andrii Sohor ◽  
...  
Keyword(s):  
Distribution Function ◽  
Mass Distribution ◽  
Dynamic Compression ◽  
Center Of Mass ◽  
Three Dimensional ◽  
The Earth ◽  
The Mean ◽  
Mass Distribution Function ◽  
The Given ◽  
Derivatives Of

Purpose. To investigate the features of the algorithm implementation for finding the derivatives of the spatial distribution function of the planet's masses with the use of high-order Stokes constants and, on the basis of this, to find its analytical expression. According to the given methodology, to carry out calculations with the help of which to carry on the study of dynamic phenomena occurring inside an ellipsoidal planet. The proposed method involves the determination of the derivatives of the mass distribution function by the sum, the coefficients of which are obtained from the system of equations, which is incorrect. In order to solve it, an error-resistant method for calculating unknowns was used. The implementation of the construction is carried out in an iterative way, while for the initial approximation we take the three-dimensional function of the density of the Earth's masses, built according to Stokes constants up to the second order inclusive, by dynamic compression by the one-dimensional density distribution, and we determine the expansion coefficients of the derivatives of the function in the variables to the third order inclusive. They are followed by the corresponding density function, which is then taken as the initial one. The process is repeated until the specified order of approximation is reached. To obtain a stable result, we use the Cesaro summation method (method of means).. The calculations performed with the help of programs that implement the given algorithm, while the achieved high (ninth) order of obtaining the terms of the sum of calculations. The studies of the convergence of the sum of the series have been carried out, and on this basis, a conclusion has been made about the advisability of using the generalized finding of the sums based on the Cesaro method. The optimal number of contents of the sum terms has been chosen, provides convergence both for the mass distribution function and for its derivatives. Calculations of the deviations of mass distribution from the mean value ("inhomogeneities") for extreme points of the earth's geoid, which basically show the total compensation along the radius of the Earth, have been performed. For such three-dimensional distributions, calculations were performed and schematic maps were constructed according to the taken into account values of deviations of three-dimensional distributions of the mean ("inhomogeneities") at different depths reflecting the general structure of the Earth's internal structure. The presented vector diagrams of the horizontal components of the density gradient at characteristic depths (2891 km - core-mantle, 700 km - middle of the mantle, also the upper mantle - 200, 100 km) allow us to draw preliminary conclusions about the global movement of masses. At the same time, a closed loop is observed on the “core-mantle” edge, which is an analogy of a closed electric circuit. For shallower depths, differentiation of vector motions is already taking place, which gives hope for attracting these vector-grams to the study of dynamic motions inside the Earth. In fact, the vertical component (derivative with respect to the z variable) is directed towards the center of mass and confirms the main property of mass distributions - growth when approaching the center of mass. The method of stable solution of incorrect linear systems is applied, by means of which the vector-gram of the gradient of the mass distribution function is constructed. The nature of such schemes provides a tool for possible causes of mass redistribution in the middle of the planet and to identify possible factors of tectonic processes in the middle of the Earth, i.e indirectly confirms the gravitational convection of masses. The proposed technique can be used to create detailed models of density functions and its characteristics (derivatives) of the planet's interior, and the results of numerical experiments - to solve tectonics problems.

Reconstructing the Mass Distribution Function of a Two-Span Beam With an Overhang via the Fundamental Mode

2020 ◽  
pp. 2043011
Author(s):  
Li-Hua Zhang ◽  
Min He ◽  
Qi-Shen Wang ◽  
I. Elishakoff
Keyword(s):  
Inverse Problem ◽  
Distribution Function ◽  
Mass Distribution ◽  
Positive Solutions ◽  
Fundamental Mode ◽  
Basic Equations ◽  
Mass Distribution Function ◽  
Polynomial Stiffness ◽  
Stiffness Distribution

In this paper, we discuss the following inverse problem: how to reconstruct the mass distribution function of a two-span beam with an overhang via its polynomial fundamental mode and polynomial stiffness function. This leads to a basic equations group constituted by the coefficients of the mass distribution and the stiffness distribution function. To make the basic equations group match, one way is to divide it into two sub- equations, and solve them. We specify the method for solving this inverse problem, and research the existence and rationality of the positive solutions.

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