Scholarship & Research
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Item A multi-wavelength study of dwarf galaxies with active massive black holes(Montana State University - Bozeman, College of Letters & Science, 2023) Kimbrell, Seth Jordan; Chairperson, Graduate Committee: Amy E. Reines; This is a manuscript style paper that includes co-authored chapters.Dwarf galaxies which host massive black holes with M less than or equivalent to 106M circled dot give us an opportunity to better understand the formation mechanism behind the supermassive black holes that live in the center of galaxies. Studying how common massive black holes in dwarfs are is an important step in constraining the channels that led to those supermassive black holes. An important part of that study is understanding in what types of dwarf galaxies we can expect to find massive black holes. I present a multi-wavelength study of dwarf galaxies which attempts to find any trends in the morphologies of the hosts of active massive black holes. I begin by modeling the structures of a sample of galaxies which have been identified as black hole hosts; I then perform an identical modeling on a sample of galaxies which show no signs of hosting a massive black hole. I finish by describing an X-ray search for massive black holes among irregular/disturbed galaxies, including the discovery of a very bright X-ray source which is extremely likely to be a massive black hole in a dwarf-dwarf merger. This is one of the first active massive black holes discovered in such a late-stage merger, and it is also notable for radiating at nearly its upper limit.Item Investigation of physically aware routing and wavelength assignment (RWA) algorithms for next generation transparent optical networks(Montana State University - Bozeman, College of Engineering, 2010) Hahn, Timothy Allen; Chairperson, Graduate Committee: Brendan MumeyOptical networks form the foundation of today's information infrastructure. Current generation optical networks consist largely of point-to-point electronically transmitted links which switch between nodes and repeaters. There is a trend in optical networking to move from the current generation opaque networks toward transparent networks. Transparent networks use only optical devices, eliminating the costly need for OEO conversions. Unfortunately, transparent networks present a unique challenge in maintaining acceptable signal quality levels. This research is an investigation of RWA algorithms in transparent optical networks. We present RAPTOR, a custom built discrete event program to simulate optical networks. RAPTOR uses its physically aware modules to accurately calculate three of the dominant physical impairments. RAPTOR is fast and multi-threaded. We introduce several new performance metrics. RAPTOR enables us to study transparent optical networks in a unique and realistic manner. We conduct an extensive performance analysis of existing RWA algorithms. We explore many different traffic models, traffic loads, signal quality, and network topologies in a comprehensive fashion. We directly compare the leading RWA algorithms in a manner has not been done before. We studied new RWA algorithms in two fields: Dynamic Programming and Ant Colony Optimization. Our new Dynamic Programming based algorithm has the best overall performance in most scenarios. It is flexible and adapts well to all network conditions we studied. It shows good promise for future optical networks.