Modeling the Environments of Gamma-Ray Burst Host Galaxies
Gamma-ray bursts are the signatures of extraordinarily high-energy events occurring in our universe. These phenomena have long been considered excellent tools for probing star formation in distant galaxies, but recent evidence suggests that long-duration (> 2s) gamma-ray bursts occur preferentially in metal-poor environments. Understanding the nature of this bias is extremely important in order to properly evaluate the utility of these objects as tracers of star formation at high redshifts.
I began this work as a research-for-credit project while a graduate student at the University of Hawai’i in September 2006, and have continued this work as a Research Assistantship with Dr. Lisa Kewley.
Levesque, E. M. and Kewley, L. J. 2007, ApJL, 667, L121
The Physical Properties of Red Supergiants
Red supergiants are a helium-burning phase in the evolution of massive stars that until recently was poorly understood and reproduced by the predictions of stellar evolutionary models. This research aims to make the first accurate determination of these stars’ physical properties in our own galaxy, as well as in massive star populations of nearby Local Group galaxies.
I began work on this project through the National Science Foundation’s Research Experience for Undergraduates program in the summer of 2004, working with Dr. Philip Massey, and have continued my work on this research over the past three years.
Levesque, E. M., Massey, P., Olsen, K. A. G., & Plez, B. 2007, ASPCS, in press
Massey, P., Plez, B., Levesque, E. M., Olsen, K. A. G., Silva, D. R., Clayton, G. C. 2007, ASPCS, in press
Levesque, E. M., Massey, P., Olsen, K. A. G., & Plez, B. 2007, ApJ, 667, 202
Massey, P., Levesque, E. M., Olsen, K. A. G., Plez, B., & Skiff, B. 2007, ApJ, 660, 301
Massey, P., Levesque, E. M., Plez, B. 2006, ApJ, 646, 1203
Levesque, E. M., Massey, P., Olsen, K.A.G., Plez, B., Josselin, E., Maeder, A., Meynet, G. 2006, ApJ, 645, 1102
Massey, P., Plez, B., Levesque, E. M., Olsen, K.A.G., Josselin, E., Clayton, G. 2005, ApJ, 634, 1286
Levesque, E. M., Massey, P., Olsen, K.A.G., Plez, B., Josselin, E., Maeder, A., Meynet, G. 2005, ApJ 628, 973
Beryllium Abundances in Metal-Poor Stars
This project was my first work as a graduate student, done through a Research Assistantship with Dr. Ann Boesgaard. I analyzed the spectra of more than thirty halo dwarf stars, modeling their physical parameters and measuring their oxygen and beryllium abundances to determine the relation between the processes that produce these elements and how this correlation is affected by these stars’ membership in the accretive and dissipative stellar populations within our galaxy.
Boesgaard, A. M., Levesque, E. M., Rich, J. A. 2007, First Stars III AIP conference proceedings, in press
Modeling Supersonic Jets in Active Galactic Nuclei
I worked on this project as an undergraduate research assistant with Dr. Sebastian Heinz of MIT’s Center for Space Research, running two- and three-dimensional simulations of collimated supersonic jets in galaxy clusters, which included their interaction with inter-cluster medium bubbles, dark matter, and characteristic radiative cooling processes. I helped to develop data analysis techniques for these complex simulations, and this work was published as part of a larger paper describing the interaction of jets with galaxy clusters.
Heinz, S., Bruggen, M., Young, A., & Levesque, E. 2006, MNRAS, 373, 65
Search for Interstellar Deuterium Oxide
I began work on this project during the summer of 2005, analyzing L-band data taken at the Westerbork Synthesis Radio Telescope in search of possible detections of deuterium oxide. We were searching for the 1191 MHz hyperfine splitting triplet. While many of the observatons turned up non-detections, we did make one potential detection in the direction of Cas A. Our results let us place upper limits on deuterium oxide optical depths.
Analysis of the Diffuse Ionized Gas Fraction in SINGG Galaxies
This work grew out of research done with Dr. Sally Oey, then of Lowell Observatory, as part of the MIT Astronomy Field Camp. I analyzed data from the SINGG survey and worked to determine the ratio of low-density ionized gas to total HII regions.
