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When a self-gravitating spherical gas cloud collapses or accretes onto a central mass, the inner region of the cloud develops a density profile $\rho\propto r^{-3/2}$ and the velocity approaches free-fall. We show that in this region,…

Astrophysics · Physics 2009-10-31 Dong Lai , Peter Goldreich

The circumgalactic medium (CGM) is responsive to kinetic disruptions generated by nearby astrophysical events. In this work, we study the saturation and dissipation of turbulent hydrodynamics within the CGM through an extensive array of 252…

Astrophysics of Galaxies · Physics 2024-06-28 Alex Lv , Lile Wang , Renyue Cen , Luis C. Ho

We experimentally investigate the Lagrangian dynamics of finite-sized, neutrally buoyant droplets in homogeneous isotropic turbulence. The droplet size follows a log-normal distribution whose average value decreases with increasing Reynolds…

Fluid Dynamics · Physics 2026-03-02 Lu Li , Yi-Bao Zhang , Yaning Fan , Federico Toschi , Chao Sun

In the past years we have experienced an increasing interest in understanding of the physical properties of collisionless plasmas, mostly because of the large number of astrophysical environments, e.g. the intracluster medium (ICM),…

Astrophysics of Galaxies · Physics 2015-05-20 Grzegorz Kowal , D. A. Falceta-Goncalves , A. Lazarian

In all spatial dimensions $d$, we study the static and dynamical properties of a generalized Smoluchowski equation which describes the evolution of a gas obeying a logotropic equation of state, $p=A\ln\rho$. A logotrope can be viewed as a…

Statistical Mechanics · Physics 2009-11-11 Pierre-Henri Chavanis , Clement Sire

Self-similar solutions provide good descriptions for the gravitational collapse of spherical clouds or stars when the gas obeys a polytropic equation of state, $p=K\rho^\gamma$ (with $\gamma\le 4/3$). We study the behaviors of nonradial…

Astrophysics · Physics 2009-10-31 Dong Lai

We study thermal-gravitational instability in simplified models for protogalactic halos using three-dimensional hydrodynamic simulations. The simulations followed the evolution of gas with radiative cooling down to T = 10^4 K, background…

Astrophysics · Physics 2009-11-11 Chang Hyun Baek , Hyesung Kang , Jongsoo Kim , Dongsu Ryu

The complex interplay between turbulence, magnetic fields, and self-gravity leads to the formation of molecular clouds out of the diffuse interstellar medium (ISM). One avenue of studying this interplay is by analyzing statistical features…

Astrophysics of Galaxies · Physics 2017-02-22 Frank Otto , Weiguang Ji , Hua-bai Li

While interstellar gas is known to be supersonically turbulent, the injection processes of this turbulence are still unclear. Many studies suggest a dominant role of gravitational instabilities. However, their effect on galaxy morphology…

Astrophysics of Galaxies · Physics 2023-04-26 Jérémy Fensch , Frédéric Bournaud , Noé Brucy , Yohan Dubois , Patrick Hennebelle , Joakim Rosdahl

In the presence of self-gravity, we investigate the self-similar dynamics of a relativistically hot gas with or without shocks in astrophysical processes of stellar core collapse, formation of compact objects, and supernova remnants with…

Astrophysics · Physics 2009-11-13 Yu-Qing Lou , Yi Cao

The gravitational collapse of cylindrically distributed perfect fluid is studied. We assume the collapsing speed of fluid is very large and investigate such a situation by recently proposed high-speed approximation scheme. We show that if…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Ken-ichi Nakao , Yoshiyuki Morisawa

Major mergers are considered to be a significant source of turbulence in clusters. We performed a numerical simulation of a major merger event using nested-grid initial conditions, adaptive mesh refinement, radiative cooling of primordial…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-28 W. Schmidt , C. Byrohl , J. F. Engels , C. Behrens , J. C. Niemeyer

We use both numerical and analytical approaches to study the dynamics of the gravitational collapse in the framework of the relativistic theory of gravitation (RTG). We use various equations of state for the collapsing matter and relatively…

General Relativity and Quantum Cosmology · Physics 2016-09-15 K. V. Antipin , A. I. Dubikovsky , P. K. Silaev

(Abridged). In this paper, we present results from a large set of numerical simulations that demonstrate that H2 formation occurs rapidly in turbulent gas. Starting with purely atomic hydrogen, large quantities of molecular hydrogen can be…

Astrophysics · Physics 2008-11-26 S. C. O. Glover , M. -M. Mac Low

Some pressure and pressure-velocity correlation in a direct numerical simulations of a three-dimensional turbulent flow at moderate Reynolds numbers have been analyzed. We have identified a set of pressure-velocity correlations which…

Chaotic Dynamics · Physics 2009-10-31 L. Biferale , P. Gualtieri , F. Toschi

We present semi-analytical similarity solutions for the inside-out, expansion-wave collapse of initially virialized gas clouds with non-isothermal equations of state. Results are given for the family of negative-index polytropes, but we…

Astrophysics · Physics 2009-10-28 Dean E. McLaughlin , Ralph E. Pudritz

We present a discussion of the effects induced by bulk viscosity either on the very early Universe stability and on the dynamics associated to the extreme gravitational collapse of a gas cloud. In both cases the viscosity coefficient is…

General Relativity and Quantum Cosmology · Physics 2009-03-24 Nakia Carlevaro , Giovanni Montani

We performed simulations of self-gravitating hydrodynamic turbulence to model the formation of filaments, clumps and cores in molecular clouds. We find that when the mass on the initial computational grid is comparable to the Jeans mass,…

Astrophysics · Physics 2007-05-23 David A. Tilley , Ralph E. Pudritz , James Wadsley

Using a suite of 3D hydrodynamical simulations of star-forming molecular clouds, we investigate how the density probability distribution function (PDF) changes when including gravity, turbulence, magnetic fields, and protostellar outflows…

Astrophysics of Galaxies · Physics 2022-03-14 Sabrina M. Appel , Blakesley Burkhart , Vadim A. Semenov , Christoph Federrath , Anna L. Rosen

The molecular component of the Galaxy is comprised of turbulent, magnetized clouds, many of which are self-gravitating and form stars. To understand how these clouds' evolution may depend on their level of turbulence, mean magnetization,…

Astrophysics · Physics 2009-10-31 Eve C. Ostriker , Charles F. Gammie , James M. Stone