Related papers: Analytical Expressions for Spiral Arm Gravitationa…
We perform simulations in a simple model that aims to mimic the hydrodynamic evolution of a relativistic fluid during a cosmological first-order phase transitions. The observable we are concerned with is hereby the spectrum of gravitational…
We test whether the spiral patterns apparent in many large disk galaxies should be thought of as dynamical features that are stationary in a co-rotating frame for > t_{dyn}, as implied by the density wave approach for explaining spiral…
In the density wave theory of spiral structure, the grand-design two-armed spiral pattern is taken to rotate rigidly in a galactic disc with a constant, definite pattern speed. The observational measurement of the pattern speed of the…
We argue that primordial gravitational waves have a spectral break and its information is quite useful for exploring the early universe. Indeed, such a spectral break can be a fingerprint of the end of inflation, and the amplitude and the…
In spiral galaxies, the pitch angle, $\alpha$, of the spiral arms is often proposed as a discriminator between theories for the formation of the spiral structure. In Lin-Shu density wave theory, $\alpha$ stays constant in time, being simply…
We present Smoothed Particle Hydrodynamics (SPH) simulations of the response of gas discs to a spiral potential. These simulations show that the commonly observed spurs and feathering in spiral galaxies can be understood as being due to…
We present the results of hydrodynamical simulations of nonaxisymmetric gas flow past a gravitating compact object in two dimensions. Calculations were performed with uniform flow as well as with transverse velocity and density gradients.…
We explore tidal interactions of a galactic disk with Toomre parameter Q ~ 2 embedded in rigid halo/bulge with a point mass companion moving in a prescribed parabolic orbit. Tidal interactions produce well-defined spiral arms and extended…
The ``galactic shocks'' \citep{fujimoto68,roberts69} is investigated using a full three-dimensional hydrodynamic simulations, taking into account self-gravity of the ISM, radiative cooling, and star formation followed by energy feedback…
We derive in this an expression for the rotation of plane of polarization, of an electromagnetic wave, induced by the field of a gravitational wave propagating along the same direction $\approx \f{G\mu d^2\Omega^4}{3\o}$, $\o$ and $\Omega$…
Galaxies and galaxy clusters are observed to have a rather non-trivial radial behaviour. The observations show that the radial profiles change from one power-law profile near the centre to another power-law profile in the outer region. We…
This paper considers particle propagation in a cylindrical molecular communication channel, e.g. a simplified model of a blood vessel. Emitted particles are influenced by diffusion, flow, and a vertical force induced e.g. by gravity or…
We have imaged a sample of 45 face-on spiral galaxies in the K-band, to determine the morphology of the old stellar population, which dominates the mass in the disk. The K-band images of the spiral galaxies have been used to calculate…
One-dimensional blood flow model accuracy has been verified in many studies. This work is about introducing gravity into a one-dimensional model. For this purpose, gravitational force was introduced into the existing model. The boundary…
"Granular elasticity," useful for calculating static stress distributions in granular media, is generalized by including the effects of slowly moving, deformed grains. The result is a hydrodynamic theory for granular solids that agrees well…
Analytical expressions are provided for the configurations of an inextensible, flexible, twistable inertial string rotating rigidly about a fixed axis. Solutions with trivial radial dependence are helices of arbitrary radius and pitch.…
We consider two minimal models of active fluid droplets that exhibit complex dynamics including steady motion, deformation, rotation and oscillating motion. First we consider a droplet with a concentration of active contractile matter…
The angular momentum radiated in gravitational scattering can be changed by performing a supertranslation of the asymptotic metric, i.e. by adding radiation with infinite wavelenght to the metric. This puzzling property can be avoided by…
We compare the stellar motion around a spiral arm created in two different scenarios, transient/co-rotating spiral arms and density-wave-like spiral arms. We generate Gaia mock data from snapshots of the simulations following these two…
Binary systems of two compact objects circularize and spiral toward each other via the emission of gravitational waves. The coupling of the spins of each object with the orbital angular momentum causes the orbital plane to precess, which…