Astronomy and Astrophysics – Astronomy
Scientific paper
Aug 1992
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992phdt.........5m&link_type=abstract
Ph.D. Thesis Florida Univ., Gainesville.
Astronomy and Astrophysics
Astronomy
Astronomical Models, Barred Galaxies, Galactic Structure, Mathematical Models, Spiral Galaxies, Algorithms, Boltzmann Transport Equation, Computer Programs, Gravitational Fields, Halos, Velocity Distribution, Viscosity
Scientific paper
A two-component, self-consistent computer code to model spiral galaxies was written and tested and a method of inducing and controlling bar formation is developed. This work presents a departure from former modeling work done at the University of Florida, which depended on the beam scheme, a hydrodynamical code with a number of limitations. In particular, only the gas component could be modeled, no self-gravitational forces were included, and the viscosity inherent to the code could not be controlled easily. These shortcomings are overcome in the new algorithm. Most importantly, an attempt has been made to keep the models self-consistent. No perturbing potentials are imposed or required to excite bar and spiral structure. The code can model both the stellar and the gaseous component of a spiral galaxy. The stellar component feels only gravitational forces, while the gas component feels both gravitational and viscous forces. In addition, a halo force can be imposed for the purpose of stabilizing the disk. The code is a hybrid grid/smooth particle code. The gravitational forces are calculated on a Cartesian grid using a Fast Fourier Transform, while the gas viscous forces are calculated in a smooth particle manner. A mechanism for creating warm, featureless, stable disks is developed by taking moments of the collision less Boltzmann equation. In order to induce and control bar and spiral arm formation, the stabilizing stellar velocity dispersions are reduced in the center of the disk, but maintained in the outer regions. A bar forms naturally in the interior and the rotation of this bar helps maintain spiral structure in the outer gas disk. Realistic-looking spiral features are maintained in the gas component for as long as the models are calculated. A wide variety of bar and spiral structure can be formed by varying the size of the unstable central region, the rate of 'turn on', of the heating and the halo mass. We would like to test the model results by comparing them with observations and so a second part of the thesis consists of observing and reducing 21 cm line data of NGC 1398 and NGC 1784 at the Very Large Array. Low (C/D array) and high (B/C) resolution data were obtained, calibrated and combined to make maps of the integrated column density and mean radial velocity of the neutral hydrogen.
No associations
LandOfFree
Numerical modeling of barred spiral galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Numerical modeling of barred spiral galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Numerical modeling of barred spiral galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1168534