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A parametric method similar to autoregressive spectral estimators is proposed to determine the probability density function (pdf) of a random set. The method proceeds by maximizing the likelihood of the pdf, yielding estimates that perform…

Data Analysis, Statistics and Probability · Physics 2009-10-31 T. Dudok de Wit , E. Floriani

We analyse the distribution of CO brightness temperature and integrated intensity in M51 at ~40 pc resolution using new CO data from the Plateau de Bure Arcsecond Whirlpool Survey (PAWS). We present probability distribution functions (PDFs)…

Modern observations of the interstellar medium (ISM) in galaxies detect a variety of atomic and molecular species. The goal is to connect these observations to the astrochemical properties of the ISM. 3D hydro-chemical simulations attempt…

Astrophysics of Galaxies · Physics 2019-02-20 Thomas G. Bisbas , Andreas Schruba , Ewine F. van Dishoeck

We present a first principle approach to obtain analytical predictions for spherically-averaged cosmic densities in the mildly non-linear regime that go well beyond what is usually achieved by standard perturbation theory. A large deviation…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-25 Cora Uhlemann , Sandrine Codis , Christophe Pichon , Francis Bernardeau , Paulo Reimberg

We analyze circumgalactic medium (CGM) in a suite of high-resolution cosmological re-simulations of a Milky-Way size galaxy and show that CGM properties are quite sensitive to details of star formation--feedback loop modelling. The…

Astrophysics of Galaxies · Physics 2016-03-09 Cameron J. Liang , Andrey V. Kravtsov , Oscar Agertz

We analytically calculate the star formation efficiency and dense self-gravitating gas fraction in the presence of magneto-gravo-turbulence using the model of Burkhart (2018), which employs a piecewise lognormal and powerlaw density…

Astrophysics of Galaxies · Physics 2019-07-24 Blakesley Burkhart , Philip Mocz

According to modern developments in turbulence theory, the "dissipation" scales (u.v. cut-offs) $\eta$ form a random field related to velocity increments $\delta_{\eta}u$. In this work we, using Mellin's transform combined with the Gaussain…

Fluid Dynamics · Physics 2009-11-11 Victor Yakhot

We show that the inter-cloud Larson scaling relation between mean volume density and size $\rho\propto R^{-1}$, which in turn implies that mass $M\propto R^2$, or that the column density $N$ is constant, is an artifact of the observational…

Astrophysics of Galaxies · Physics 2015-06-11 Ballesteros-Paredes , J. , D'Alessio , P. , Hartmann , L. W.

The probability density functions (PDFs) for energy dissipation rates, created from time-series data of grid turbulence in a wind tunnel, are analyzed in a high precision by the theoretical formulae for PDFs within multifractal PDF theory…

Fluid Dynamics · Physics 2015-06-03 Toshihico Arimitsu , Naoko Arimitsu , Hideaki Mouri

The Central Limit Theorem does not hold for strongly correlated stochastic variables, as is the case for statistical systems close to criticality. Recently, the calculation of the probability distribution function (PDF) of the magnetization…

Statistical Mechanics · Physics 2025-03-28 Sankarshan Sahu , Bertrand Delamotte , Adam Rançon

Turbulence is a complex phenomenon that plays a critical role in the interstellar medium (ISM). Previous simulations and observations show that the probability density function (PDF) of gas density in isothermal and compressible systems…

Astrophysics of Galaxies · Physics 2025-03-26 Xunchuan Liu

A theoretical formula for the probability density function (PDF) of velocity derivatives in a fully developed turbulent flow is derived with the multifractal aspect based on the generalized measures of entropy, i.e., the extensive Renyi…

Statistical Mechanics · Physics 2009-11-07 N. Arimitsu , T. Arimitsu

Aging in spin glasses is analyzed via the Probability Density Function (PDF) of the heat transfer between system and bath over a small time $\delta t$. The PDF contains a Gaussian part, describing reversible fluctuations, and an exponential…

Soft Condensed Matter · Physics 2007-05-23 Paolo Sibani , Henrik Jeldtoft Jensen

We investigate velocity probability distribution functions (PDF) of sheared hard-sphere suspensions. As observed in our Stokes flow simulations and explained by our single-particle theory, these PDFs can show pronounced deviations from a…

Soft Condensed Matter · Physics 2008-07-24 Jens Harting , Hans J. Herrmann , Eli Ben-Naim

Despite over 30 years of study, the mass-area relationship within and among clouds is still poorly understood both observationally and theoretically. Modern extinction datasets should have sufficient resolution and dynamic range to…

The gravitational evolution of the cosmic one-point Probability Distribution Function (PDF) can be estimated using an analytic approximation that combines gravitational Perturbation Theory (PT) with the Edgeworth expansion around a Gaussian…

Astrophysics · Physics 2007-05-23 P. Fosalba , E. Gaztanaga , E. Elizalde

The emergence and development of a power-law tail (PLT) at the high-density end of the observed column-density distribution is thought to be indicative for advanced evolution of star-forming molecular clouds. As shown from many numerical…

Astrophysics of Galaxies · Physics 2021-10-04 L. Marinkova , T. Veltchev , Ph. Girichidis , S. Donkov

The joint probability distribution function (PDF) of the density within multiple concentric spherical cells is considered. It is shown how its cumulant generating function can be obtained at tree order in perturbation theory as the Legendre…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-19 Francis Bernardeau , Christophe Pichon , Sandrine Codis

We investigate the single-point velocity probability density function (PDF) in three-dimensional fully developed homogeneous isotropic turbulence within the framework of PDF equations focussing on deviations from Gaussianity. A joint…

Fluid Dynamics · Physics 2011-02-18 Michael Wilczek , Anton Daitche , Rudolf Friedrich

The one-point probability distribution function (pdf) of the large-scale density field is an important tool to follow the evolution of cosmological structures. In this paper we present a new model for this pdf for all regimes and all…

Astrophysics · Physics 2009-11-10 Patrick Valageas , Dipak Munshi
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