Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)

Legacy Department


Committee Member

Dr. Mark D. Leising, Committee Chair

Committee Member

Dr. Dieter Hartmann

Committee Member

Dr. Jeremy King

Committee Member

Dr. Catalina Marinescu


Type Ia supernovae have many applications in astronomy, yet with fundamental properties still not fully understood, new methods for investigating the environment of a supernova need to be developed. A light echo is produced from the scattering of light from a bright source and can be used to analyze the dust in the vicinity of the supernova and learn invaluable information about the source. These techniques can put constraints on explosion and progenitor models. Although light echo detections from Type Ia supernovae are rare, with only seven total extragalactic detections, this could be due to the lack of thorough late-epoch monitoring. Since key information is determined from even a single light echo detection, light echo searches should be undertaken in the future to supplement our understanding of supernovae. As part of our collaborative campaign for studying the emission of supernovae at late epochs, we have added two light echoes to a small sample size of Type Ia supernova light echo detections: SN 2009ig in NGC 1015 and a dual echo from SN 2007af in NGC 5584. Both echoes were observed with the Hubble Space Telescope and allow for the most detailed images of Type Ia supernova light echoes to date. Three filters (F555W, F814W, and F350LP) captured the echoes obtained with the Wide Field Camera 3, and since both host galaxies were imaged as part of the same observing program, these cases will be the best comparable light echo pairs. We also further investigate the light echoes from SN 2006X in NGC 4321 and SN 1998bu in NGC 3368 from Hubble Space Telescope archival images. Analyses performed on the images gives crucial insight into the dusty environment of the host galaxy and the surroundings of the supernova. The outer echo from SN 2007af was created from an interstellar dust sheet located ~800 pc in front of the supernova, while the inner echo could be from interstellar or circumstellar origin. A circumstellar light echo could imply a single degenerate progenitor. The dust is closer to the supernova for the echo in SN 2009ig. Exploring the color of the echoes gives implications on the dust type, and both light echo cases have atypical color evolution from model predictions, which suggests abnormal dust is involved. The echoes from SN 2006X and double echo from SN 1998bu show the evolution of the echoes over a long time period, which can be compared to past findings by multiple teams. The echoes show remarkable similarity to other Type Ia echo detections, and with more discoveries, the transition of light echoes from normal emission can be investigated, which could further probe the supernova ejecta. Using a process we developed, we calculate the magnitude differences between Hubble Space Telescope and standard filters in the case of normal supernovae. We conclude by comparing all light echo detections to date and discussing the future goals of this work.



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