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Thermal ionization is a critical process at temperatures T > 10 3 K, particularly during star formation. An increase in ionization leads to a decrease in nonideal magnetohydrodynamics (MHD) resistivities, which has a significant impact on…

Solar and Stellar Astrophysics · Physics 2022-10-05 Pierre Marchand , Vincent Guillet , Ugo Lebreuilly , Mordecai-Mark Mac Low

Dynamical aspects of cosmological model in an extended gravity theory have been investigated in the present work. We have adopted a simplified approach to obtain cosmic features, which in fact requires more involved calculations. A…

General Relativity and Quantum Cosmology · Physics 2021-06-10 B. Mishra , S. K. Tripathy , Sankarsan Tarai

All anomalous velocity increases until now observed during the Earth flybys of the spacecrafts Galileo, NEAR, Rosetta, Cassini and Messenger have been correctly calculated by computer simulation using an asymmetric field term in addition to…

General Physics · Physics 2007-11-27 Hans-Juergen Busack

We use numerical relativity to study the violent preheating era at the end of inflation. This epoch can result in highly nonlinear fluctuations in density and gravitational potential which feed back onto the averaged expansion rate -- an…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-15 Ryn Grutkoski , Hayley J. Macpherson , John T. Giblin , Joshua Frieman

In previous papers we have shown that scattering of spacecraft nucleons from dark matter gravitationally bound to the earth gives a possible explanation of the flyby velocity anomalies. In addition to flyby velocity changes arising from the…

Space Physics · Physics 2010-12-21 Stephen L. Adler

The discovery that the cosmic expansion is accelerating has been followed by an intense theoretical and experimental response in physics and astronomy. The discovery implies that our most basic notions about how gravity work are violated on…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-15 Robert R. Caldwell , Marc Kamionkowski

Many astronomers have speculated that the solar system contains undiscovered massive planets or a distant stellar companion. The acceleration of the solar system barycenter can constrain the mass and position of the putative companion. In…

Astrophysics · Physics 2008-11-26 Nadia L. Zakamska , Scott Tremaine

In this paper we investigate the feasibility of bremsstrahlung radiation from `nonthermal' electrons as a source of hard X-rays from the intracluster medium of clusters of galaxies. With an exact treatment of the Coulomb collisions in a…

Astrophysics · Physics 2013-03-08 Vahé Petrosian , William E. East

We present measurements on Earth's gravitational acceleration (g) using an in-house developed cold atom gravimeter (CAG) in an atomic fountain geometry. In the setup, the laser cooled $^{87}Rb$ atoms are launched vertically up in the…

A surprising and unexpected phenomenon observed during Cassini's Grand Finale was the spacecraft charging to positive potentials in Saturn's ionosphere. Here, the ionospheric plasma was depleted of free electrons with negatively charged…

Space Physics · Physics 2021-03-16 Zeqi Zhang , Ravindra T. Desai , Yohei Miyake , Hideyuki Usui , Oleg Shebanits

A 3D simulation of the upper part of the solar convective zone is used to derive constraints about the averaged and dynamic properties of solar turbulent convection. Theses constraints are then used to compute the acoustic energy supply…

Astrophysics · Physics 2007-05-23 R. Samadi , A. Nordlund , R. F. Stein , M. J. Goupil , I. Roxburgh

Using 2D particle-in-cell (PIC) plasma simulations we study electron acceleration by temperature anisotropy instabilities, assuming conditions typical of above-the-loop-top (ALT) sources in solar flares. We focus on the long-term effect of…

Solar and Stellar Astrophysics · Physics 2022-01-19 Mario Riquelme , Alvaro Osorio , Daniel Verscharen , Lorenzo Sironi

Thermal conduction has been suggested as a possible mechanism by which sufficient extra heating is provided in radiation-dominated accretion flows. We consider the extreme case in which the generated energy due to the viscosity and the…

Astrophysics · Physics 2007-05-23 Mohsen Shadmehri , Fazeleh Khajenabi

Anderson, et al., find the measured trajectories of Pioneer 10 and 11 spacecraft deviate from the trajectories computed from known forces acting on them. This unmodelled acceleration can be accounted for by non-isotropic radiation of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Louis K. Scheffer

Understanding the conditions conducive to particle acceleration at collisionless, non-relativistic shocks is important for the origin of cosmic rays. We use hybrid (kinetic ions -- fluid electrons) kinetic simulations to investigate…

High Energy Astrophysical Phenomena · Physics 2023-09-07 Luca Orusa , Damiano Caprioli

We analyze the time evolution of the kinetic properties of nuclear matter produced in heavy-ion collisions at Fermi energies. The collision system is simulated using Constrained Molecular Dynamics (CoMD) transport calculations whose output…

Nuclear Theory · Physics 2023-11-01 Thomas Onyango , Aldo Bonasera , Ralf Rapp

Magnetic reconnection is a fundamental plasma process that is thought to play a key role in the production of nonthermal particles associated with explosive phenomena in space physics and astrophysics. Experiments at high-energy-density…

Plasma Physics · Physics 2020-12-07 Samuel Totorica , Masahiro Hoshino , Tom Abel , Frederico Fiuza

In this work, we study the non-minimally-coupled Higgs model in the context of warm inflation scenario on both metric and Palatini approaches. We particularly consider a dissipation parameter of the form $\Gamma=C_{T}T$ with $C_{T}$ being a…

General Relativity and Quantum Cosmology · Physics 2023-07-20 Thammarong Eadkhong , Punsiri Dam-O , Phongpichit Channuie , Davood Momeni

We consider electron acceleration by obliquely propagating fast mode waves in magnetically dominated accretion disk coronae. For low coronal plasma densities, acceleration can exceed Coulomb drag at lower energies and energize electrons out…

Astrophysics · Physics 2016-08-30 Hui Li , James A. Miller

By means of three dimensional, high resolution hydrodynamical simulations we study the orbital evolution of weakly eccentric or inclined low-mass protoplanets embedded in gaseous discs subject to thermal diffusion. We consider both…

Earth and Planetary Astrophysics · Physics 2023-03-15 S. Cornejo , F. S. Masset , R. O. Chametla , S. Fromenteau