Hydrostatic equilibrium and stellar structure inf(R)gravity

Dissipative fluids out of hydrostatic equilibrium

In the context of the Müller-Israel-Stewart second order phenomenological theory for dissipative fluids, we analyze the effects of thermal conduction and viscosity in a relativistic fluid, just after its departure from hydrostatic equilibrium, on a time scale of the order of relaxation times. Stability and causality conditions are contrasted with conditions for which the ”effective inertial mas...

Hydrostatic equilibrium conditions in the galactic halo

The large scale distributions of gas, magnetic field and cosmic rays in the galactic halo are investigated. Our model is based on the analysis of all-sky surveys of H i gas (Lei-den/Dwingeloo survey), soft X-ray radiation (ROSAT all-sky survey), high energy γ-ray emission (EGRET > 100 MeV), and radio-continuum emission (408 MHz survey). We found a stable hydrostatic equilibrium configuration of...

Stellar Structure and Evolution

Necessary and sufficient condition for hydrostatic equilibrium in general relativity

We present explicit examples to show that the ‘compatibility criterion’ [recently obtained by us towards providing equilibrium configurations compatible with the structure of general relativity] which states that: for a given value of σ[≡ (P0/E0) ≡ the ratio of central pressure to central energy-density], the compactness ratio u[≡ (M/R), whereM is the total mass andR is the radius of the config...

Fluctuations in Finite N Equilibrium Stellar Systems

Gravitational amplification of Poisson noise in stellar systems is important on large scales. For example, it increases the dipole noise power by roughly a factor of six and the quadrupole noise by 50% for a King model profile. The dipole noise is amplified by a factor of fifteen for the core-free Hernquist model. The predictions are computed using the dressed-particle formalism of Rostoker & R...