نتایج جستجو برای: stellar dynamics
تعداد نتایج: 521564 فیلتر نتایج به سال:
The coalescence of massive black hole (MBH) binaries following galaxy mergers is one of the main sources of low-frequency gravitational radiation. A higher-order relativistic phenomenon, the recoil as a result of the non-zero net linear momentum carried away by gravitational waves, may have interesting consequences for the demography of MBHs at the centers of galaxies. We study the dynamics of ...
Already slightly eccentric orbits, such as those occupied by many old stars in the Galactic disk, are not well approximated by Lindblad’s epicycle theory. Here, alternative approximations for flat orbits in axisymmetric stellar systems are derived and compared to results from numeric integrations. All of these approximations are more accurate than Lindblad’s classical theory. I also present app...
The central regions of disk galaxies are hosts to supermassive black holes whose masses show a tight correlation with the properties of surrounding stellar bulges. While the exact origin of this dependency is not clear, it can be related to the very basic properties of dark matter halos and the associated gas and stellar dynamics in the central kpc of host galaxies. In this review we discuss so...
Recent progress on the structure and dynamics of bulges is reviewed. Those aspects that link galaxy bulges either to oblate spheroids akin to elliptical galaxies or to rapidly-rotating, flattened systems more nearly resembling the products of disk internal transformations, are highlighted. The analysis of surface brightness profiles derived from HST data is reviewed to show that unresolved nucl...
We present MUSE, a software framework for combining existing computational tools for different astrophysical domains into a single multiphysics, multiscale application. MUSE facilitates the coupling of existing codes written in different languages by providing inter-language tools and by specifying an interface between each module and the framework that represents a balance between generality a...
We consider the dynamical evolution of a disk of stars orbiting a central black hole. In particular, we focus on the effect of the stellar mass function on the evolution of the disk, using both analytic arguments and numerical simulations. We apply our model to the ring of massive stars at ≃ 0.1pc from the Galactic Center, assuming that the stars formed in a cold, circular disk, and find that o...
we have studied the effect of hypothetical cosmions on the core stability of main sequence stars (of populations i and ii). cosmions, with a mass of 4-10 gev/c2 and a scattering cross section with nucleons of approximately 10-36 cm2 could prevail in transporting heat in the stellar cores. raby [17] showed the existence of a local thermal instability caused by the presence of cosmions in the sol...
Understanding galaxies, the basic components of the universe, is one of the most challenging tasks we meet. There are two major phenomena of spiral galaxies which are not given acceptable explanation. One is the almost constant rotation curve and the other is the bar pattern. In my previous work, I proposed to use curvilinear coordinate system and a symmetry principle to study galaxy patterns. ...
We use a large sample of galaxies from the Two Micron All Sky Survey (2MASS) and the Sloan Digital Sky Survey (SDSS) to calculate galaxy luminosity and stellar mass functions in the local Universe. We estimate corrections for passband shifting and galaxy evolution, as well as present-day stellar mass-to-light (M/L) ratios, by fitting the optical–near-infrared galaxy data with simple models. Acc...
We are using adaptive optics on Keck and the VLT to probe the dynamics and star formation in Seyfert and QSO nuclei, obtaining spatial resolutions better than 0.1′′ in the Hand K-bands. The dynamics are traced via the 2.12 μm H2 1-0 S(1) line, while the stellar cluster is traced through the CO 2-0 and 6-3 absorption bandheads at 2.29 μm and 1.62 μm respectively. Matching disk models to the H2 r...
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