相关论文: Pattern speeds in interacting galaxies
The disks of spiral galaxies commonly show a lopsided mass distribution, with a typical fractional amplitude of 10 % for the Fourier component m=1. This is seen in both stars and gas, and the amplitude is higher by a factor of two for…
A brief review is given of different methods used to determine the pattern speeds of the Galactic bar and spiral arms. The Galactic bar rotates rapidly, with corotation about halfway between the Galactic center and the Sun, and outer…
We use an N-body simulation to study the 3-D density distribution of spirals, and the resulting stellar vertical velocities. Relative to the disc's rotation, the phase of the spiral's peak density away from the mid-plane trails that at the…
We investigate the figure rotation of dark matter halos identified in Lambda CDM simulations. We find that when strict criteria are used to select suitable halos for study, 5 of the 222 halos identified in our z=0 simulation output undergo…
Aims. New or refined methods for determining instantaneous scalar and vector pattern speeds from a restricted domain are developed, for applications in N-body simulations or in galaxies. Methods. The general feature used throughout follows…
We have studied a sample containing about 6000 OB stars with proper motions and trigonometric parallaxes from the Gaia DR2 catalogue. The following parameters of the angular velocity of Galactic rotation have been found:…
Theories that attempt to explain the dynamical relationship between bar and spiral patterns in galactic disks make different predictions about the radial profile of the pattern speed. These are tested for the H-alpha bar and spiral patterns…
The pattern speeds of spiral galaxies are closely related to the flow of material in their disks. Flows that follow the `precessing ellipses' paradigm (see e.g., Kalnajs 1973) are likely associated with slowly rotating spirals, which have…
The dynamical nature and formation mechanism(s) of galactic spiral arms remain long-standing problems in astrophysics. Most theoretical work is based on analytic calculations or idealised simulations, which has yielded several theories of…
Previous work has related the Galactic bar to structure in the local stellar velocity distribution. Here we show that the bar also influences the spatial gradients of the velocity vector via the Oort constants. By numerical integration of…
Spiral density wave theory attempts to describe the spiral pattern in spiral galaxies in terms of a long-lived wave structure with a constant pattern speed in order to avoid the winding dilemma. The pattern is consequently a rigidly…
We describe methods to measure simultaneously the orientation angle $\psi$ and pattern speed $\Omega$ from single snapshots of simulated barred galaxies. Unlike previous attempts, our approach is unbiased, precise, and consistent in the…
A co-rotation radius is a key characteristic of disc galaxies that is essential to determine the angular speed of the spiral structure $\Omega_{p}$, and therefore understand its nature. In the literature, there are plenty of methods to…
We measure the mean Galactocentric radial component of the velocity of stars ($v_R$) in the disk at 8 kpc$<R<28$ kpc in the direction of the anticenter. For this, we use the Apache Point Galactic Evolution Experiment (APOGEE). Furthermore,…
We present a study of the effect of bulge mass on the evolution of bar pattern speed in isolated disk galaxies using N-body simulations. Earlier studies have shown that disk stars at the inner resonances can transfer a significant amount of…
The density wave theory predicted some physical offsets among different tracers of star formation. To test this prediction, here we compiled data on 40 galaxies searched observationally for a physical offset between spiral arm tracers, and…
We have used the Tremaine-Weinberg method to measure the angular speed of rotation for the bar in the SB0 galaxy NGC 936. With this technique, the bar's pattern speed, Omega_p, can be derived from the luminosity and stellar-kinematic…
The rotation velocity of the spiral pattern of the Galaxy is determined by direct observation of the birthplaces of open clusters of stars in the galactic disk as a function of their age. Our measurement does not depend on any specific…
The mean Galactocentric radial velocities $\langle v_{R}\rangle(R,\varphi)$ of luminous red giant stars within the mid-plane of the Milky Way reveal a spiral signature, which could plausibly reflect the response to a non-axisymmetric…
The lifetime of the structure in grand design spiral galaxies is observationally ill-determined, but is essentially set by how accurately the pattern's rotation can be characterized by a single angular pattern speed. This paper derives a…