H I Line Profiles of Galaxies: Tilted Ring Models

• Main Author: Nelson, Erica
• Format: Others
• Published: Scholarship @ Claremont 2008
• Subjects: Spiral galaxies; Hydrogen; HI; Tilted ring model; Astrophysics and Astronomy; Physical Sciences and Mathematics
• Online Access: http://scholarship.claremont.edu/pomona_theses/27; http://scholarship.claremont.edu/cgi/viewcontent.cgi?article=1026&context=pomona_theses

Two-dimensional information on the kinematics and spatial distribution of gas in spiral galaxies is encoded in radio observations of their one-dimensional 21-cm neutral hydrogen (HI) line profiles. More than ten thousand HI profiles have been published and are publicly available. In order to explore the parameter space mapped out by the 21-cm neutral hydrogen line pro file, we have modified and run a FORTRAN-based computer simulation code. We have identified 7 control parameters that define the morphology of the modelled galaxy: they describe the neutral hydrogen gas distribution (density and spatial location of the gas), characteristics of its rotation curve, warps, asymmetries, and finally, the viewing angle. All except the last of these parameters tell us significant physical information about the galaxy but a determination of them is not immediately apparent from the two-dimensional 21-cm line profile. Hence, the goal of this exploration is to find meaningful correlations between the observed 21-cm line profile features and the underlying physical parameters.