scholarly journals EXPONENTIAL AND POWER LAW DISTRIBUTION OF MASS CLUSTERS IN A (MAGNETIC-LIKE) DEPOSITION MODEL OF ELONGATED GRAINS IN 2D PILES

2004 ◽  
Vol 15 (08) ◽  
pp. 1121-1141 ◽  
Author(s):  
K. TROJAN ◽  
M. AUSLOOS ◽  
R. CLOOTS
Keyword(s):  
Distribution Function ◽  
Mass Distribution ◽  
Power Law ◽  
Power Law Distribution ◽  
Grain Rotation ◽  
Cluster Mass ◽  
Granular Pile ◽  
Granular Piles ◽  
Hamiltonian Parameters ◽  
Mass Distribution Function

A generalized magnetically controlled ballistic rain-like deposition (MBD) model of granular piles has been numerically investigated in 2D. The grains are taken to be elongated disks whence characterized by a two-state scalar degree of freedom, called "nip", their interaction being described through a Hamiltonian. The results are discussed in order to search for the effect of nip flip (or grain rotation from vertical to horizontal and conversely) probability in building a granular pile. The characteristics of creation of + (or -) nip's clusters and clusters of holes (missing nips) are analyzed. Two different cluster-mass regimes have been identified, through the cluster-mass distribution function which can be exponential or have a power law form depending on whether the nip flip (or grain rotation) probability is large or small. Analytical forms of the exponent are empirically found in terms of the Hamiltonian parameters.

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.

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