by Juan Enrique Cabanela Larrinaga
Under the supervision of Professor Roberta M. Humphreys
- I am using the Minnesota Automated Plate Scanner (APS) to construct two galaxy catalogs. The Minnesota Automated Plate Scanner Pisces-Perseus Survey (MAPS-PP) is used to search for modern-day remnant signatures of large-scale structure formation processes, specifically, galaxy alignments relative to surrounding large-scale structure. Weak evidence for such alignments is found, although the type of alignments seen don't strongly support any one large-scale structure formation model.
- Comparison of the MAPS-PP to pre-existing galaxy catalogs has led to the discovery that the Uppsala General Catalog and Third Reference Catalog of Galaxies exhibit a very strong measurement bias: their diameters are measured to different isophotes at different galaxy inclinations. Therefore previous determinations of the diameter function and the internal extinction properties of other galaxies (most of which have relied one of these two galaxy catalogs) have suffered from a biased diameter measurement.
- I avoid this bias by using the APS data (which is obtained using automated computer-based criteria for measuring the structural properties of images digitized from photographic plates) to construct a catalog of over 200,000 galaxies within 30 arcdeg of the North Galactic Pole (the MAPS-NGP). The MAPS-NGP is the deepest galaxy catalog constructed over such a large area of the sky and used to re-evaluate previous investigations of the internal extinction in galaxies.