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We model in simple terms the angular momentum (J) problem of galaxy formation in CDM, and identify the key elements of a scenario that can solve it. The buildup of J is modeled via dynamical friction and tidal stripping in mergers. This…

Astrophysics · Physics 2009-11-07 Avishai Dekel , Ariyeh H. Maller

We study the dynamics of the critical collapse of a spherically symmetric scalar field. Approximate analytic expressions for the metric functions and matter field in the large-radius region are obtained. In the central region, owing to the…

General Relativity and Quantum Cosmology · Physics 2024-05-13 Jun-Qi Guo , Yu Hu , Pan-Pan Wang , Cheng-Gang Shao

I review the progress of SPH calculations for modelling galaxies, and resolving gas dynamics on GMC scales. SPH calculations first investigated the response of isothermal gas to a spiral potential, in the absence of self gravity and…

Astrophysics of Galaxies · Physics 2015-05-20 Clare Dobbs

We review recent results of non-ideal magnetohydrodynamic models for the fragmentation of molecular clouds and the collapse of cloud cores to form protostar-disk systems. Thin-disk models can elucidate many aspects of the physical problem…

Solar and Stellar Astrophysics · Physics 2013-04-09 Shantanu Basu , Nicole D. Bailey , Wolf B. Dapp

The purpose of this article is to show that when dynamically cold, dissipationless self-gravitating systems collapse, their evolution is a strong function of the symmetry in the initial distribution. We explore with a set of pressure-less…

Astrophysics · Physics 2009-11-07 C. M. Boily , E. Athanassoula , P. Kroupa

We discuss the stability and construct dynamical configurations describing the gravitational collapse of unstable neutron stars with realistic equations of state compatible with the recent LIGO-Virgo constraints. Unlike other works that…

General Relativity and Quantum Cosmology · Physics 2020-06-17 J. M. Z. Pretel , M. F. A. da Silva

In this work, we employ a soft-sphere discrete element method with a cohesion implementation to model the dynamical process of sub-km-sized cohesive rubble piles under continuous spinup. The dependencies of critical spin periods $T_c$ on…

Earth and Planetary Astrophysics · Physics 2021-02-24 Shoucun Hu , Derek C. Richardson , Yun Zhang , Jianghui Ji

Dynamical expansion of H II regions around star clusters plays a key role in dispersing the surrounding dense gas and therefore in limiting the efficiency of star formation in molecular clouds. We use a semi-analytic method and numerical…

Astrophysics of Galaxies · Physics 2016-03-23 Jeong-Gyu Kim , Woong-Tae Kim , Eve C. Ostriker

An extensive numerical campaign of particle mechanics calculations that predict microstructure formation and evolution during die compaction, up to relative densities close to one, of monodisperse plastic spheres that exhibit power-law…

Materials Science · Physics 2018-01-30 Marcial Gonzalez , Payam Poorsolhjouy , Alexander Thomas , Jili Liu , Kiran Balakrishnan

The general formulas of a non-rotating dynamic thin shell that connects two arbitrary cylindrical regions are given using Israel's method. As an application of them, the dynamics of a thin shell made of counter-rotating dust particles,…

General Relativity and Quantum Cosmology · Physics 2014-11-17 P. R. C. T. Pereira , Anzhong Wang

We report two-dimensional phase-field simulations of locally-conserved coarsening dynamics of random fractal clusters with fractal dimension D=1.7 and 1.5. The correlation function, cluster perimeter and solute mass are measured as…

Soft Condensed Matter · Physics 2009-11-07 Azi Lipshtat , Baruch Meerson , Pavel V. Sasorov

By means of high-resolution N-body simulations we revisited the dissipationless collapse scenario for galaxy formation. We considered both single-component collapses and collapses of a cold stellar distribution in a live dark matter halo.…

Astrophysics · Physics 2009-11-11 C. Nipoti , P. Londrillo , L. Ciotti

The formation of massive objects via gravitational collapse is relevant both for explaining the origin of the first supermassive black holes and in the context of massive star formation. Here, we analyze simulations of the formation of…

We study the collapse of pebble clouds with a statistical model to find the internal structure of comet-sized planetesimals. Pebble-pebble collisions occur during the collapse and the outcome of these collisions affect the resulting…

Earth and Planetary Astrophysics · Physics 2017-07-26 Karl Wahlberg Jansson , Anders Johansen

The secular evolution of disk galaxies is largely driven by resonances between the orbits of 'particles' (stars or dark matter) and the rotation of non-axisymmetric features (spiral arms or a bar). Such resonances may also explain kinematic…

Astrophysics of Galaxies · Physics 2023-05-19 Chris Hamilton , Elizabeth A. Tolman , Lev Arzamasskiy , Vinícius N. Duarte

Many questions in physical cosmology regarding the thermal history of the intergalactic medium, chemical enrichment, reionization, etc. are thought to be intimately related to the nature and evolution of pregalactic structure. In particular…

Astrophysics · Physics 2007-05-23 Tom Abel , Greg L. Bryan , Michael L. Norman

The size of the smallest dark matter collapsed structures, or protohalos, is set by the temperature at which dark matter particles fall out of kinetic equilibrium. The process of kinetic decoupling involves elastic scattering of dark matter…

High Energy Physics - Phenomenology · Physics 2013-07-30 Jonathan M. Cornell , Stefano Profumo , William Shepherd

We decompose the rotation curves of 34 bright spiral galaxies into baryonic and dark matter components. Stellar mass profiles are created by applying color-M/L relations to near-infrared and optical photometry. We find that the radial…

Astrophysics · Physics 2009-11-11 Susan A. Kassin , Roelof S. de Jong , Benjamin J. Weiner

Complex colloidal cluster morphologies are desirable for the fabrication of advanced materials, such as photonic crystals and meta-materials, and can be formed through evaporation-driven packing. By coupling lattice Boltzmann and discrete…

Soft Condensed Matter · Physics 2026-05-07 Junyu Yang , Abhinav Naga , Xitong Zhang , Halim Kusumaatmaja

Here I report the scaling relation between the baryonic masses and the scale lengths of stellar discs from $\sim$1000 morphologically late-type galaxies. The baryonic mass-size relation is a single power-law $R_\ast \propto M_b^{0.38}$…

Astrophysics of Galaxies · Physics 2017-12-20 Po-Feng Wu