A woman in the archives: the legacy of Margaret C. Norton

Margaret C. Norton (1891-1984) was the first state archivist of Illinois and a prominent personality in the early history of the archival profession. She made an indelible mark on the history of the early archival profession through her many written works, her work concerning the nuts and bolts of the archival profession, her involvement with the Society of American Archivists (SAA) and other organizations. Drawing from numerous influences she was a prolific writer, thinker and worker who held strong opinions at a time when it was not common for women to do so. This thesis uses Norton\u27s personal papers and supplemental secondary resources to analyze the views and writings of this strong woman who was one of the pioneers in her profession

Using gravitational waves to study neutron stars in general relativity and alternative theories of gravity

LIGO's detection of gravitational waves emitted by a binary black hole merger in 2015 opened a new window into our universe. The era of multi-messenger astronomy began in 2017 with the detection of binary neutron star merger GW170817 and its electromagnetic counterpart GRB170817A. Gravitational wave observations have become a valuable tool for studying diverse areas of physics. Gravitational waves are particularly suited to tests of general relativity in the strong field regime and to studies of nuclear matter in extreme conditions. The work presented in this thesis uses gravitational wave data to contribute to our understanding of neutron stars, nuclear matter, and general relativity, explore the capabilities of current and future detectors, and provide a foundation for future studies of alternate theories of gravity. Binary neutron star merger GW170817 offered new insights into nuclear physics, astrophysics, gravitational physics, and many other disciplines. The first study in this thesis combines the multi-messenger signals from GW170817 with state-of-the-art nuclear theory to place tight constraints on neutron star radii and tidal deformabilities, improving the radius measurement by a factor of 2. This study also constrains the nuclear equation of state and predicts that future neutron star-black hole mergers are unlikely to be disrupted and thus unlikely to have an electromagnetic counterparts. The second study in this thesis builds upon the first and focuses on the capabilities of aLIGO-Virgo, LIGO A+, LIGO Voyager, the Einstein Telescope, and Cosmic Explorer to study neutron star-black hole mergers without electromagnetic counterparts. The results demonstrate that neither the present LIGO-Virgo detector network nor its near-term upgrades are likely to distinguish between neutron star-black hole and binary black hole mergers. Third-generation instruments such as Cosmic Explorer may be able to make the distinction given an event with favorable parameters. This result emphasizes the need for third-generation detectors. The third study widens the scope of this thesis and analyzes data from all gravitational wave events detected to date to test for birefringence. Birefringence occurs when a wave's left- and right-handed polarizations propagate along different equations of motion. Bayesian inference was performed on the 4th-Open Gravitational-wave Catalog (4-OGC) using a parity-violating waveform. The vast majority of events show no deviation from general relativity, but the two most massive events (GW190521 and GW191109) support the birefringence hypothesis. Excluding these two events, the constraint on the parity-violating energy scale is an improvement over previous results by a factor of five. Future detections of massive binary black hole mergers will help shed light on the origin of this apparent birefringence. The final study in this thesis provides a foundation that will improve future tests of general relativity using neutron stars. Any gravitational waveform for a system with a neutron star must include tidal effects. Even though tidal deformabilities in alternative theories can differ from their general relativistic counterparts, tests of general relativity seldom take this into account. The tidal deformabilities for static neutron stars in scalar-tensor theories with a focus on spontaneous scalarization are derived. The results demonstrate that tidal deformabilities can differ significantly between theories. Future analyses can apply these results alone or combine them with the parameter estimation methods developed in the first part of this thesis for more accurate tests of scalar modes in gravitational waves from neutron star mergers

Tidal Deformability of Neutron Stars in Scalar-Tensor Theories of Gravity

Gravitational waves from compact binary coalescences are valuable for testing theories of gravity in the strong field regime. By measuring neutron star tidal deformability using gravitational waves from binary neutron stars, stringent constraints were placed on the equation of state of matter at extreme densities. Tidal Love numbers in alternative theories of gravity may differ significantly from their general relativistic counterparts. Understanding exactly how the tidal Love numbers change will enable scientists to untangle physics beyond general relativity from the uncertainty in the equation of state measurement. In this work, we explicitly calculate the fully relativistic $l \geq 2$ tidal love numbers for neutron stars in scalar-tensor theories of gravitation. We use several realistic equations of state to explore how the mass, radius, and tidal deformability relations differ from those of general relativity. We find that tidal Love numbers and tidal deformabilities can differ significantly from those in general relativity in certain regimes. The electric tidal deformability can differ by $\sim 200\%$, and the magnetic tidal deformability differs by $\sim 300 \%$. These deviations occur at large compactnesses ($C = M/r \gtrsim 0.2$) and vary slightly depending on the equation of state. This difference suggests that using the tidal Love numbers from general relativity could lead to significant errors in tests of general relativity using the gravitational waves from binary neutron star and neutron-star--black-hole mergers.Comment: Accepted to AP

Assembling large, complex environmental metagenomes

The large volumes of sequencing data required to sample complex environments deeply pose new challenges to sequence analysis approaches. De novo metagenomic assembly effectively reduces the total amount of data to be analyzed but requires significant computational resources. We apply two pre-assembly filtering approaches, digital normalization and partitioning, to make large metagenome assemblies more comput\ ationaly tractable. Using a human gut mock community dataset, we demonstrate that these methods result in assemblies nearly identical to assemblies from unprocessed data. We then assemble two large soil metagenomes from matched Iowa corn and native prairie soils. The predicted functional content and phylogenetic origin of the assembled contigs indicate significant taxonomic differences despite similar function. The assembly strategies presented are generic and can be extended to any metagenome; full source code is freely available under a BSD license.Comment: Includes supporting informatio

Using gravitational waves to distinguish between neutron stars and black holes in compact binary mergers

In August 2017, the first detection of a binary neutron star merger, GW170817, made it possible to study neutron stars in compact binary systems using gravitational waves. Despite being the loudest gravitational wave event detected to date (in terms of signal-to-noise ratio), it was not possible to unequivocally determine that GW170817 was caused by the merger of two neutron stars instead of two black holes from the gravitational-wave data alone. That distinction was primarily due to the accompanying electromagnetic counterpart. This raises the question: under what circumstances can gravitational-wave data alone, in the absence of an electromagnetic signal, be used to distinguish between different types of mergers? Here, we study whether a neutron star-black hole binary merger can be distinguished from a binary black hole merger using gravitational-wave data alone. We build on earlier results using chiral effective field theory to explore whether the data from LIGO and Virgo, LIGO A+, LIGO Voyager, the Einstein Telescope, or Cosmic Explorer could lead to such a distinction. The results suggest that the present LIGO-Virgo detector network will most likely be unable to distinguish between these systems even with the planned near-term upgrades. However, given an event with favorable parameters, third-generation instruments such as Cosmic Explorer will be capable of making this distinction. This result further strengthens the science case for third-generation detectors.Comment: 16 pages, 7 figures, 13 table

Action-Packed Action Research: How Comic Books, Questions, and Reflection Can Transform Information Literacy Instruction

How many questions can you generate when looking at a single comic panel? Which are researchable, and why? These are questions that we’ve asked our students and our library colleagues. We invite you to ask these questions and more, and consider the broader significance of question-asking and reflective teaching to information literacy and ask if there is a place for comics -- or image-laden materials -- in your classroom

Analytical sun synchronous low-thrust manoeuvres

Article describes analytical sun synchronous low-thrust manoeuvres

Stringent constraints on neutron-star radii from multimessenger observations and nuclear theory

The properties of neutron stars are determined by the nature of the matter that they contain. These properties can be constrained by measurements of the star's size. We obtain stringent constraints on neutron-star radii by combining multimessenger observations of the binary neutron-star merger GW170817 with nuclear theory that best accounts for density-dependent uncertainties in the equation of state. We construct equations of state constrained by chiral effective field theory and marginalize over these using the gravitational-wave observations. Combining this with the electromagnetic observations of the merger remnant that imply the presence of a short-lived hyper-massive neutron star, we find that the radius of a $1.4\,\rm{M}_\odot$ neutron star is $R_{1.4\,\mathrm{M}_\odot} = 11.0^{+0.9}_{-0.6}~{\rm km}$ (90% credible interval). Using this constraint, we show that neutron stars are unlikely to be disrupted in neutron-star black-hole mergers; subsequently, such events will not produce observable electromagnetic emission.Comment: 39 pages, 4 figure