Senior Honors Projects, 2010-current

Preferred Name - First Author

Witherspoon, Catherine

Date of Award

Spring 2017

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Department of Physics and Astronomy

Advisor(s)

Anca Constantin

Abstract

Astrophysical masers are natural microwave amplifiers by stimulated emission and when detected in galaxy centers, they are extremely luminous (i.e. millions of times more luminous than those associated with typical star-forming regions in the spiral arms of our own Milky Way). A fraction of water megamasers detected in 22 GHz emission in galactic nuclear regions are in a disk-like configuration, which makes them extremely valuable for providing direct geometrical distances to galaxies and the most precise and accurate masses of supermassive black holes. Nevertheless, these systems are extremely rare. While the exact mechanism of water maser emission production is not known, there is tentative evidence that the disk masing conditions are associated with accretion of matter onto black holes that are as massive as millions to billions of Suns, which is usually detected as active galactic nucleus activity. In particular, megamaser disk emission appears to be associated with the active galactic nuclei that are obscured by cosmic dust in their host galaxies’ circum-nuclear regions. Improvements on their detection rates in future surveys rely on better understanding of their physical properties, in relation to those of their host galaxies. Using data from the Wide-Field Infrared Survey Explorer we systematically study the mid-infrared properties of the galaxies with and without nuclear water maser emission to better constrain the connection between water masing activity and the circumnuclear dust absorption and radiation reprocessing in galaxy centers.

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