Now showing items 1-20 of 77

• #### A First Reconnaissance of the Atmospheres of Terrestrial Exoplanets Using Ground-Based Optical Transits and Space-Based UV Spectra ﻿

(2020-05-14)
Decades of ground-based, space-based, and in some cases in situ measurements of the Solar System terrestrial planets Mercury, Venus, Earth, and Mars have provided in-depth insight into their atmospheres, yet we know almost ...
• #### Applications of High-Resolution Observations of Millimeter Wavelengths ﻿

(2015-12-17)
nterferometric observations at millimeter wavelengths provide a precious, detailed view of certain astrophysical objects. This thesis is composed of studies that both rely on and enable this technique to study the structure ...
• #### Black Hole Accretion Disks and Jets: Connecting Simulations and Theory ﻿

(2013-09-25)
In recent years, general relativistic magnetohydrodynamic (GRMHD) simulations have produced more realistic models for black hole disks and jets. However the complexity of the simulations has created a disconnect between ...
• #### The Bright Side of Black Holes: Radiation From Black Hole Accretion Disks ﻿

(2015-05-15)
An understanding of radiation is paramount for connecting observations of accretion disks with the theory of black holes. In this thesis, we explore via radiative transfer postprocessing calculations the observational ...
• #### Charting our Uncharted Milky Way ﻿

(2020-05-14)
Our position in the Milky Way, buried within its disk, makes it extraordinarily difficult to piece together the structure of our home Galaxy. We know the Milky Way is a barred spiral but many questions, including the precise ...
• #### Companions to M-Dwarfs: Statistics and Habitability in New Dimensions ﻿

(2019-05-15)
Stellar binaries and their ubiquity have implications for a variety of astrophysics. Their configurations hold clues to the formation and dynamical histories of stars and planets. The most common type of binary systems may ...
• #### Computational Approaches to Studying the Stellar Populations of Galaxies ﻿

(2019-05-14)
Major open questions remain in our understanding of the formation and evolution of galaxies in our universe, and the best tracers of these galactic histories are the stars within. The properties of stellar populations -- ...
• #### Computational Modeling of Large-Scale Structure With Abacus ﻿

(2019-05-16)
Interpreting galaxy surveys in a cosmological context requires an accurate forward model of large-scale structure. N-body simulations are the state-of-the-art tool for this but are not without their challenges. For one, ...
• #### Constraining the Evolution of Galaxies over the Interaction Sequence with Multiwavelength Observations and Simulations ﻿

(2013-10-18)
Interactions are crucial for galaxy formation and profoundly affect their evolution. However, our understanding of the impact of interactions on star formation and activity of the central supermassive black hole remains ...
• #### Core-collapse Supernova Progenitors in the Era of Untargeted Transient Searches ﻿

(2014-06-06)
Core-collapse supernovae (SNe) are the highly energetic explosions of massive stars (> 8 solar masses) that are pervasive in their influence throughout astrophysics. They are the phenomenon with primary responsibility for ...
• #### Cosmic Extremes: Probing Energetic Transients With Radio Observations ﻿

(2018-05-11)
With the advent of sensitive facilities like the Karl G. Jansky Very Large Array and planning well underway for vastly more powerful wide-field interferometers like the Square Kilometer Array, the study of radio astrophysical ...
• #### Counting Stars: Developing Probabilistic Cataloging for Crowded Fields ﻿

(2018-05-09)
The depth of next generation surveys poses a great data analysis challenge: these surveys will suffer from crowding, making their images difficult to deblend and catalog. Sources in crowded fields are extremely covariant ...
• #### Development and Application of Tools to Characterize Transiting Astrophysical Systems ﻿

(2014-06-06)
Since the discovery of the first exoplanets (planets outside our Solar System) more than 20 years ago, there has been an increasing need for photometric and spectroscopic models to characterize these systems. While imaging ...
• #### Discovery of Giant Gamma-ray Bubbles in the Milky Way ﻿

(2012-08-09)
Based on data from the Fermi Gamma-ray Space Telescope, we have discovered two gigantic gamma-ray emitting bubble structures in our Milky Way (known as the Fermi bubbles), extending $\sim 50$ degrees above and below the ...
• #### Distances, Masses, Radii, and Metallicities of the Small Stars in the Solar Neighborhood ﻿

(2016-05-16)
Data from the NASA Kepler spacecraft indicate that small planets are common around the smallest main sequence stars (M dwarfs). Rocky planets transiting M dwarfs will be the best targets for atmospheric characterization ...
• #### The Diversity and Versatility of Gamma-Ray Bursts ﻿

(2015-05-17)
Gamma-ray bursts (GRBs) are the most energetic explosions in the Universe, thus providing a unique laboratory for the study of extreme astrophysical processes. In parallel, their large luminosity makes GRBs a premier probe ...
• #### The Dynamics and Evolution of Supermassive Black Holes in Merging Galaxies ﻿

(2012-08-03)
This thesis is a theoretical study of supermassive black holes (SMBHs) in merging galaxies. We consider the dynamics that govern inspiralling SMBH pairs and gravitational-wave (GW) recoiling SMBHs, as well as the fueling ...
• #### The Evolution of Rotation and Magnetism in Small Stars Near the Sun ﻿

(2016-05-19)
Despite the prevalence of M dwarfs, the smallest and most common type of main sequence star, their sizes, compositions, and ages are not well-constrained. Empirical determination of these properties is important for gaining ...
• #### Exploring Exotic Transients: Stellar Explosions, Tidal Disruptions, and Compact Object Mergers in the Golden Age of Time-Domain Astronomy ﻿

(2019-05-10)
The advent of wide-field time-domain surveys has dramatically increased the transient discovery rate and directly led to uncovering new phenomena, such as superluminous supernovae (SLSNe) and tidal disruption events (TDEs), ...
• #### Exploring the Long-Term and Extreme Variability of Stars ﻿

(2012-08-23)
This thesis presents observational studies of long-term and extreme variability of stars with the Digital Access to a Sky Century@Harvard (DASCH) project. Stellar variations over decades are poorly explored. With the unique ...