Hydromagnetic waves in an expanding universe – cosmological MHD code tests using analytic solutions
نویسندگان
چکیده
ABSTRACT We describe how analytic solutions for linear hydromagnetic waves can be used testing cosmological magnetohydrodynamic (MHD) codes. start from the comoving MHD equations and derive amplitude evolution of in a matter-dominated, flat Einstein-de-Sitter (EdS) universe. The considered are comoving, linearly polarized Alfvén magnetosonic (fast) modified by self-gravity. solution compressible is found general adiabatic index we consider limits hydrodynamics without self-gravity addition to full solution. In these solutions, linearized solved numerically Λ cold dark matter cosmology. use numeric compare with results obtained using code arepo find good agreement when sufficient number grid points. interpret numerical damping clearly evident simulations few points further deriving wave including physical Navier–Stokes viscosity. A comparison between theory reveals that dissipation described viscosity coefficient ηnum ∝ a−5/2, where scale factor. envision our examples could useful developing new or regression existing
منابع مشابه
Cosmological Radar Ranging in an Expanding Universe ⋆
While modern cosmology, founded in the language of general relativity, is almost a century old, the meaning of the expansion of space is still being debated. In this paper, the question of radar ranging in an expanding universe is examined, focusing upon light travel times during the ranging; it has recently been claimed that this proves that space physically expands. We generalize the problem ...
متن کاملGravitational waves in an expanding Universe
We study the tensorial modes of the two-fluid model, where one of this fluids has an equation of state p = −ρ/3 (variable cosmological constant, cosmic string fluid, texture) or p = −ρ (cosmological constant), while the other fluid is an ordinary matter (radiation, stiff matter, incoherent matter). In the first case, it is possible to have a closed Universe whose dynamics can be that of an open...
متن کاملPlasma waves driven by gravitational waves in an expanding universe
In a Friedmann-Robertson-Walker (FRW) cosmological model with zero spatial curvature, we consider the interaction of the gravitational waves with the plasma in the presence of a weak magnetic field. Using the relativistic hydromagnetic equations it is verified that large amplitude magnetosonic waves are excited, assuming that both, the gravitational field and the weak magnetic field do not brea...
متن کاملGott-Kaiser-Stebbins (GKS) effect in an accelerated expanding universe
Wewanttofindthecosmologicalconstantinfluenceoncosmicmicrowavebackground(CMB)temperatureduetomovinglinearcosmicstrings.Usingthespace-timemetricofalinearcosmicstringinanacceleratedexpandinguniverse,theGott-Kaiser Stebbins(GKS)effect,asanimportantmechanisminproducingtemperaturediscontinuityinthe(CMB),isconsidered;then,itsmodificationduetotheeffectofthecosmologicalconstantiscalculated.Theresultshowsthat...
متن کاملEvolution of Information and Complexity in an Ever-Expanding Universe
Using the usual definitions of information and entropy in quantum gravity and statistical mechanics and the existing views about the relation between information and complexity, we examine the evolution of complexity in an ever expanding universe.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 2022
ISSN: ['0035-8711', '1365-8711', '1365-2966']
DOI: https://doi.org/10.1093/mnras/stac1882