Astrophysics and Astronomy Commons^™

Using Supervised Learning Algorithms As A Follow-Up Method In The Search Of Gravitational Waves From Core-Collapse Supernovae, Javier M. Antelis, Marco Cavaglia, Travis Hansen, Mannuel D. Morales, Claudia Moreno, Soma Mukherjee, Marek J. Szczepańczyk, Michele Zanolin

Physics & Astronomy Faculty Publications

We present a follow-up method based on supervised machine learning (ML) to improve the performance in the search of gravitational wave (GW) bursts from core-collapse supernovae (CCSNe) using the coherent WaveBurst (cWB) pipeline. The ML model discriminates noise from signal events by using a set of reconstruction parameters provided by cWB as features. Detected noise events are discarded yielding a reduction in the false alarm rate (FAR) and the false alarm probability thus enhancing the statistical significance. We tested the proposed method using strain data from the first half of the third observing run of advanced LIGO, and CCSNe GW …

Determining The Sources Of The Zodiacal Cloud Using Relative Velocities Of Dust Particles From High-Resolution Spectroscopy, Philip B. Mann Iii

Beyond: Undergraduate Research Journal

The zodiacal cloud is the Solar System debris disk in which the Earth’s orbit is located. The dust that comprises the cloud comes from cometary, asteroidal, interstellar, and other source populations, but the relative ratios have proven hard to determine. However, asteroidal and cometary particles typically have different types of orbits, with asteroidal particles having more circular and lower inclination orbits than cometary particles. Accordingly, the relative velocities of these groups of particles with respect to Earth are also different, and measurements of these relative velocities can help distinguish between the sources. The spectrum of the zodiacal light contains solar …

The Next Small Step, Samiya Henry

Undergraduate Research and Scholarship Symposium

As of right now, NASA and other space programs are estimating that by 2026, there will be people living in Space. Whether it be the Moon or Mars, one cannot have a functional society without a proper source of laws, especially since no one country has ownership over space. "One Small Step" will produce this source of laws, called the “Space Bill of Rights,” that will outline important matters like the trade of resources, medical care, government officials, and will ensure the preservation of our physical and figurative footsteps in space. This Space Bill of Rights is made up of …

The Solar-Electric Sail: Application To Interstellar Migration And Consequences For Seti, Gregory Matloff

Publications and Research

The Solar-Electric Sail accelerates by reflecting positively charged solar wind ions. If it is used to propel an interstellar migration mission, its interstellar cruise velocity relative to the home star cannot exceed the solar wind velocity. In an effort to analytically determine interstellar cruise velocity for a 107 kg generation ship, a constant solar wind velocity within the heliosphere of a Sun-like star of 600 km/s is assumed. The solar wind proton density at 1 AU is also considered constant at 10 protons per cubic centimeter. Solar wind density is assumed to decrease with the inverse square of solar distance. …

Nano-Fabricated Atomic Waveguides For Inertial Measurements, Adrian S. Orozco

Physics & Astronomy ETDs

Atom-based inertial measurement systems can measure acceleration and rotation very precisely in the laboratory. The central element of these systems is atom interferometry where the phase shifts are sensitive to inertial forces experienced by the atom. This phenomenon has been used to make atom-based gravimeters, gradiometers, and gyroscopes. Recent effort has been made to make these systems more compact which require small size, light weight, and low power (SWaP). Nano-fabricated waveguides, such as photonic waveguides or optical nanofibers, offer a promising avenue to meet these goals. They have dimensions comparable to the guided light’s wavelength producing a mode that not …

Shining A Light On Dark Sky Week, Erik Johnson

Natural Science Faculty

Have you ever seen the Milky Way? For most Americans, it is impossible to see the band of light from the galaxy outside their homes. To be able to experience the night sky as our ancestors did, we have to travel to places away from light pollution.

International Dark Sky Week, which is happening April 22-30, celebrates the night sky and offers everyone a chance to reflect on the lighting choices made around their home and in their community.

Validation Of Accelerometry As A Digital Phenotyping Measure Of Negative Symptoms In Schizophrenia, Gregory P. Strauss, Ian M. Raugh, Luyu Zhang, Lauren Luther, Hannah C. Chapman, Daniel N. Allen, Brian Kirkpatrick, Alex S. Cohen

Physics & Astronomy Faculty Research

Negative symptoms are commonly assessed via clinical rating scales; however, these measures have several inherent limitations that impact validity and utility for their use in clinical trials. Objective digital phenotyping measures that overcome some of these limitations are now available. The current study evaluated the validity of accelerometry (ACL), a passive digital phenotyping method that involves collecting data on the presence, vigor, and variability of movement. Outpatients with schizophrenia (SZ: n = 50) and demographically matched healthy controls (CN: n = 70) had ACL continuously recorded from a smartphone and smartband for 6 days. Active digital phenotyping assessments, including surveys …

Search Of The Early O3 Ligo Data For Continuous Gravitational Waves From The Cassiopeia A And Vela Jr. Supernova Remnants, Ligo Scientific Collaboration, Virgo Collaboration, Tiffany Z. Summerscales

Faculty Publications

We present directed searches for continuous gravitational waves from the neutron stars in the Cassiopeia A (Cas A) and Vela Jr. supernova remnants. We carry out the searches in the LIGO detector data from the first six months of the third Advanced LIGO and Virgo observing run using the weave semicoherent method, which sums matched-filter detection-statistic values over many time segments spanning the observation period. No gravitational wave signal is detected in the search band of 20–976 Hz for assumed source ages greater than 300 years for Cas A and greater than 700 years for Vela Jr. Estimates from simulated …

Reliability Of Quantum Simulation On Nisq-Era Devices, Karthik R. Chinni

Physics & Astronomy ETDs

We study the reliability of quantum simulation on Noisy intermediate-scale quantum (NISQ)-era devices in the presence of errors and imperfections, with a focus on exploring the relationship between the properties of the system being simulated and the errors in the output of the simulator. We first consider simulation of the Lipkin-Meshkov-Glick (LMG) model, which becomes chaotic in the presence of a background time-dependent perturbation. Here we show that the quantities that depend on the global structure of the phase space are robust, while other quantities that depend on the local trajectories are fragile and cannot be reliably extracted from the …

Beam-Spin Asymmetry Σ For Σ- Hyperon Photoproduction Off The Neutron, N. Zachariou, E. Munevar, B. L. Berman, P. Bydžovský, A. Cieplý, G. Feldman, Y. Ilieva, P. Nadel-Turonski, D. Skoupil, A. V. Sarantsev, D. P. Watts, M. J. Amaryan, G. Angelini, W. R. Armstrong, H. Atac, H. Avakian, L. Barion, M. Bashkanov, M. Battaglieri, Steffen Strauch, Et. Al.

Faculty Publications

We report a new measurement of the beam-spin asymmetry, Σ, for the γn → K ⁺ Σ− reaction using quasi-free neutrons in a liquid-deuterium target. The new dataset includes data at previously unmeasured photon energy and angular ranges, thereby providing new constraints on partial wave analyses used to extract properties of the excited nucleon states. The experimental data were obtained using the CEBAF Large Acceptance Spectrometer (CLAS), housed in Hall B of the Thomas Jefferson National Accelerator Facility (JLab). The CLAS detector measured reaction products from a liquid-deuterium target produced by an energy-tagged, linearly polarised photon beam with energies in …

Improving White Dwarfs As Chronometers With Gaia Parallaxes And Spectroscopic Metallicities, Adam Moss, Ted Von Hippel, Elliot Robinson, Kareem El-Badry, David C. Stenning, David Van Dyk, Morgan Fouesneau, Coryn A.L. Bailer-Jones, Elizabeth Jeffery, Jimmy Sargent, Isabelle Kloc, Natalie Moticska

Publications

White dwarfs (WDs) offer unrealized potential in solving two problems in astrophysics: stellar age accuracy and precision. WD cooling ages can be inferred from surface temperatures and radii, which can be constrained with precision by high-quality photometry and parallaxes. Accurate and precise Gaia parallaxes along with photometric surveys provide information to derive cooling and total ages for vast numbers of WDs. Here we analyze 1372 WDs found in wide binaries with main-sequence (MS) companions and report on the cooling and total age precision attainable in these WD+MS systems. The total age of a WD can be further constrained if its …

Measurement Of Two-Particle Correlations Of Hadrons In E+E-Collisions At Belle, Y. C. Chen, Y. J. Lee, P. Chang, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, T. Aushev, R. Ayad, V. Babu, P. Behera, K. Belous, J. Bennett, M. Bessner, T. Bilka, D. Bodrov, J. Borah, M. Bračko, P. Branchini

Faculty and Student Publications

The measurement of two-particle angular correlation functions in high-multiplicity e+e-collisions at s=10.52 GeV is reported. In this study, the 89.5 fb-1 of hadronic e+e-annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle (Δφ) and three units of pseudorapidity (Δη), defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. …

Start Making Plans For The Next Total Eclipses, Erik Johnson

Natural Science Faculty

A lunar eclipse occurs when Earth gets between the Sun and the Moon. Normally, you would see a full Moon but Earth's shadow is capable of covering the Moon entirely, making it much dimmer. A total lunar eclipse looks red due to sunlight refracted through Earth's atmosphere.

This event is visible to anyone who can see the Moon, which could be anywhere on the nighttime side of Earth. Next month on May 15, it will be visible through most of North America if it isn't cloudy.

B-Flavor Tagging At Belle Ii, F. Abudinén, N. Akopov, A. Aloisio, V. Babu, Sw Banerjee, M. Bauer, J. V. Bennett, F. U. Bernlochner, M. Bessner, S. Bettarini, T. Bilka, S. Bilokin, D. Biswas, D. Bodrov, J. Borah, M. Bračko, P. Branchini, A. Budano, M. Campajola

Faculty and Student Publications

We report on new flavor tagging algorithms developed to determine the quark-flavor content of bottom ([InlineMediaObject not available: see fulltext.]) mesons at Belle II. The algorithms provide essential inputs for measurements of quark-flavor mixing and charge-parity violation. We validate and evaluate the performance of the algorithms using hadronic [InlineMediaObject not available: see fulltext.] decays with flavor-specific final states reconstructed in a data set corresponding to an integrated luminosity of 62.8 fb- 1, collected at the [InlineEquation not available: see fulltext.] resonance with the Belle II detector at the SuperKEKB collider. We measure the total effective tagging efficiency to be εeff=(30.0±1.2(stat)±0.4(syst))%for …

Luminosity With Large Amplitude Pulses After The Initial Breakdown Stage In Intracloud Lightning Flashes, Maribeth Stolzenburg, Thomas C. Marshall, Sampath Bandara, Raymond Siedlecki

Faculty and Student Publications

Optical data are presented for two intracloud flashes in which there were five events having large amplitude, bipolar electric field change (E-change) pulses and strong VHF emissions. These bright events occurred 18.98–67.33 ms after the initiating event and 10–59 ms after the end of the initial breakdown stage. The three largest events were coincident with WorldWide Lightning Location Network detections of the sort previously associated with terrestrial gamma-ray flashes (TGFs); these pulses had range-normalized E-change amplitudes of 8.73, 8.33, and 3.81 V/m and estimated peak current magnitudes of 262, 250, and 114 kA. The other two events were 3.20 and …

Measurement Of The Branching Fraction And Cp Asymmetry For B → D ¯ 0Π Decays, T. Bloomfield, M. E. Sevior, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, P. Behera, J. Bennett, M. Bessner, T. Bilka, J. Biswal, A. Bobrov, G. Bonvicini, A. Bozek

Faculty and Student Publications

We measure the branching fractions and CP asymmetries for the decays B0→D¯0π0 and B+→D¯0π+, using a data sample of 772×106 BB¯ pairs collected at the (4S) resonance with the Belle detector at the KEKB e+e- collider. The branching fractions obtained and direct CP asymmetries are B(B0→D¯0π0)=[2.70±0.06(stat)±0.10(syst)]×10-4, B(B+→D¯0π+)=[4.53±0.02(stat)±0.15(syst)]×10-3, ACP(B0→D¯0π0)=[+0.42±2.05(stat)±1.22(syst)]%, and ACP(B+→D¯0π+)=[+0.19±0.36(stat)±0.57(syst)]%. The measurements of B are the most precise to date and are in good agreement with previous results, as is the measurement of ACP(B+→D¯0π+). The measurement of ACP for B0→D¯0π0 is the first for this mode, and the value is consistent with Standard Model expectations.

Tess Hunt For Young And Maturing Exoplanets (Thyme). Vi. An 11 Myr Giant Planet Transiting A Very-Low-Mass Star In Lower Centaurus Crux, A. W. Mann, M. L. Wood, S. P. Schmidt, M. G. Barber, J. E. Owen, B. M. Tofflemire, E. R. Newton, E. E. Mamajek, J. L. Bush, G. N. Mace, A. L. Kraus, P. C. Thao, A. Vanderburg, J. Llama, C. M. Johns-Krull, L. Prato, A. G. Stahl, S.-Y. Tang, M. J. Fields, K. A. Collins, K. I. Collins, T. Gan, Eric L.N. Jensen, J. Kamler, R. P. Schwarz, E. Furlan, C. L. Gnilka, S. B. Howell, K. V. Lester, D. A. Owens, O. Suarez, D. Mekarnia, T. Guillot, L. Abe, A. H. M. J. Triaud, M. C. Johnson, R. P. Milburn, A. C. Rizzuto, S. N. Quinn, R. Kerr, G. R. Ricker, R. Vanderspek, D. W. Latham, S. Seager, J. N. Winn, J. M. Jenkins, N. M. Guerrero, A. Shporer, J. E. Schlieder, B. Mclean, B. Wohler

Physics & Astronomy Faculty Works

Mature super-Earths and sub-Neptunes are predicted to be ≃ Jovian radius when younger than 10 Myr. Thus, we expect to find 5–15 R_⊕ planets around young stars even if their older counterparts harbor none. We report the discovery and validation of TOI 1227b, a 0.85 ± 0.05 R_J (9.5 R_⊕) planet transiting a very-low-mass star (0.170 ± 0.015 M_⊙) every 27.4 days. TOI 1227's kinematics and strong lithium absorption confirm that it is a member of a previously discovered subgroup in the Lower Centaurus Crux OB association, which we designate the Musca group. We …

A Second Planet Transiting Ltt 1445a And A Determination Of The Masses Of Both Worlds, J. G. Winters, R. Cloutier, A. A. Medina, J. M. Irwin, D. Charbonneau, N. Astudillo-Defru, X. Bonfils, A. W. Howard, H. Isaacson, J. L. Bean, A. Seifahrt, J. K. Teske, J. D. Eastman, J. D. Twicken, K. A. Collins, Eric L.N. Jensen, S. N. Quinn, M. J. Payne, M. H. Kristiansen, A. Spencer, A. Vanderburg, M. Zechmeister, L. M. Weiss, S. X. Wang, G. Wang, S. Udry, I. A. Terentev, J. Stürmer, G. Stefánsson, A. Shporer, S. Shectman, R. Sefako, H. M. Schwengeler, R. P. Schwarz, N. Scarsdale, R. A. Rubenzahl, A. Roy, L. J. Rosenthal, P. Robertson, E. A. Petigura, F. Pepe, M. Omohundro, J. M. Akana Murphy, F. Murgas, T. Močnik, B. T. Montet, R. Mennickent, A. W. Mayo, B. Massey, J. Lubin, C. Lovis, P. Lewin, D. Kasper, S. R. Kane, J. M. Jenkins, D. Huber, K. Horne, M. L. Hill, P. Gorrini, S. Giacalone, B. Fulton, T. Forveille, P. Figueira, T. Fetherolf, C. Dressing, R. F. Díaz, X. Delfosse, P. A. Dalba, F. Dai, C. C. Cortés, I. J. M. Crossfield, J. D. Crane, D. M. Conti, K. I. Collins, A. Chontos, R. P. Butler, P. Brown, M. Brady, A. Behmard, C. Beard, N. M. Batalha, J.-M. Almenara

Physics & Astronomy Faculty Works

LTT 1445 is a hierarchical triple M-dwarf star system located at a distance of 6.86 pc. The primary star LTT 1445A (0.257 M_⊙) is known to host the transiting planet LTT 1445Ab with an orbital period of 5.36 days, making it the second-closest known transiting exoplanet system, and the closest one for which the host is an M dwarf. Using Transiting Exoplanet Survey Satellite data, we present the discovery of a second planet in the LTT 1445 system, with an orbital period of 3.12 days. We combine radial-velocity measurements obtained from the five spectrographs, Echelle Spectrograph for Rocky …

Dry And Hydrated Defective Molybdenum Disulfide/Graphene Bilayer Heterojunction Under Strain For Hydrogen Evolution From Water Splitting: A First-Principle Study, Nicholas Dimakis, Sanju Gupta, Razeen Wadud, Muhammad I. Bhatti

Physics & Astronomy Faculty Publications

In search of exploiting cost-effective, highly stable, efficient, and greatly active electrocatalysts for hydrogen evolution reaction (HER), molybdenum disulfide-graphene heterostructures (MoS2/graphene) are promising, in contrast to noble metals. We used density functional theory (DFT) to examine the changes in the electronic structure of MoS2/graphene under compressive strain for structural defects in the MoS2 and graphene layers, as well as from hydration of the MoS2 layer. In the pristine MoS2/graphene heterostructure, a small bandgap (minigap) is opened at the graphene Dirac point, which is located above the Fermi energy, for dry and hydrated configurations. The presence of sulfur and carbon vacancies …

The Case For Space Environmentalism, Andy Lawrence, Meredith L. Rawls, Moriba Jah, Aaron Boley, Federico Di Vruno, Simon Garrington, Michael Kramer, Samantha Lawler, James Lowenthal, Jonathan Mcdowell, Mark Mccaughrean

Astronomy: Faculty Publications

The shell bound by the Karman line at a height of ~80–100 km above the Earth’s surface and geosynchronous orbit at ~36,000 km is defined as the orbital space surrounding the Earth. It is within this region, and especially in low Earth orbit, where environmental issues are becoming urgent because of the rapid growth of the anthropogenic space object population, including satellite ‘mega-constellations’. In this Perspective, we summarize the case for considering the orbital space around the Earth as an additional ecosystem, subject to the same care and concerns, and the same broad regulations as the oceans and the atmosphere, …

Reimagining Near-Earth Space Policy In A Post-Covid World, John C. Barentine, Jessica Heim, Aparna Venkatesan, James Lowenthal, Monica Vidaurri

Astronomy: Faculty Publications

Our planet and our species are at an existential crossroads. In the long term, climate change threatens to upend life as we know it, while the ongoing COVID-19 pandemic revealed that the world is unprepared and ill-equipped to handle acute shocks to its many systems. These shocks exacerbate the inequities and challenges already present prior to COVID in ways that are still evolving in unpredictable directions. As weary nations look toward a post-COVID world, we draw attention to both the injustice and many impacts of the quiet occupation of near-Earth space, which has rapidly escalated during this time of global …

Observing And Exploring Intrinsic Characteristics Of Type Ia Supernova, Connor Langevin

Honors Capstones

No abstract provided.

Galaxy And Mass Assembly (Gama): The Weak Environmental Dependence Of Quasar Activity At 0.1 < Z < 0.35, Clare F. Wethers, Nischal Acharya, Roberto De Propris, Jari Kotilainen, Ivan K. Baldry, Sarah Brough, Simon P. Driver, Alister W. Graham, Benne Holwerda, Andrew M. Hopkins, Angel R. López-Sánchez, Jonathan Loveday, Steven Phillipps, Kevin A. Pimbblet, Edward Taylor, Lingyu Wang, Angus H. Wright

Faculty and Staff Scholarship

Understanding the connection between nuclear activity and galaxy environment remains critical in constraining models of galaxy evolution. By exploiting the extensive cataloged data from the Galaxy and Mass Assembly survey, we identify a representative sample of 205 quasars at 0.1 < z < 0.35 and establish a comparison sample of galaxies, closely matched to the quasar sample in terms of both stellar mass and redshift. On scales <1 Mpc, the galaxy number counts and group membership of quasars appear entirely consistent with those of the matched galaxy sample. Despite this, we find that quasars are ∼1.5 times more likely to be classified as the group center, indicating a potential link between quasar activity and cold gas flows or galaxy interactions associated with rich group environments. On scales of ∼a few Mpc, the clustering strengths of both samples are statistically consistent, and beyond 10 Mpc, we find no evidence that quasars trace large-scale structures any more than the galaxy control sample. Both populations are found to prefer intermediate-density sheets and filaments to either very high-density environments or very low-density environments. This weak dependence of quasar activity on galaxy environment supports a paradigm in which quasars represent a phase in the lifetime of all massive galaxies and in which secular processes and a group-centric location are the dominant triggers of quasars at low redshift.

Untangling The Solar Wind And Magnetospheric Drivers Of The Radiation Belt Electrons, Simon Wing, Jay R. Johnson, Drew L. Turner, Aleksandr Y. Ukhorskiy, Alexander J. Boyd

Faculty Publications

Plain Language Summary

Many solar wind parameters correlate with one another, which complicates the causal-effect studies of solar wind driving of the magnetosphere. We use conditional mutual information, which is part of information theory, to untangle and isolate the effect of individual solar wind and magnetospheric drivers of the radiation belt electrons. For example, the solar wind density negatively correlates with electron phase space density (PSD) (average energy ∼1.6 MeV) with the response time lag of 15 hr. This has been attributed to the electron loss process such as magnetopause shadowing. The time lag suggests the time scale for this …

Search For Gravitational Waves Associated With Gamma-Ray Bursts Detected By Fermi And Swift During The Ligo–Virgo Run O3b, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC–2020 March 27 17:00 UTC). We conduct two independent searches: a generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence …

Mms Observations Of The Kelvin-Helmholtz Instability And Associated Ion Scale Waves, Rachel C. Rice

Doctoral Dissertations and Master's Theses

The detailed mechanisms coupling the solar wind to Earth's magnetosphere are not yet fully understood. Solar wind plasma is heated non-adiabatically as it penetrates the magnetosphere, and this process must span scale sizes. Reconnection alone is not able to account for the observed heating; other mechanisms must be at work. One potential process is the Kelvin-Helmholtz instability (KHI). The KHI is a convective instability which operates at the fluid scale in plasmas, but is capable of driving secondary process at smaller scales. Previous work has shown evidence of magnetic reconnection, various ion scale wave modes, mode conversion, and turbulence associated …

X-Ray Spectroscopy Of The O Supergiant Ζ Puppis Indicates Surprising Variation In The Wind Mass-Loss Rate On Years Timescales, Jiaming Wang , '22

Senior Theses, Projects, and Awards

We apply two mass-loss rate diagnostics described in the thesis on Chandra and XMM-Newton X-ray spectroscopic measurements of ζ Pup, one of the most luminous stars in the Milky Way and one of the closest O stars to Earth. Emission line profile analysis from new long Chandra grating observations taken during 2018 and 2019 indicates a significant 40% increase in ζ Pup’s wind mass-loss rate as compared to data taken in Chandra’s first observation cycle in 2000. Broadband spectral modeling of 20 years of XMM observations also reveal non-periodic wind mass-loss rate variation at a 40% level on timescales …

Uncertainty In Grain Size Estimations Of Volatiles On Trans-Neptunian Objects And Kuiper Belt Objects, A. Emran, V. F. Chevrier

Space and Planetary Science Faculty Publications and Presentations

We analyze the uncertainty in grain size estimation of pure methane (CH4) and nitrogen saturated with methane (N2:CH4) ices, the most abundant volatile materials on trans-Neptunian objects (TNOs) and Kuiper Belt objects (KBOs). We compare the single scattering albedo, which determines the grain size estimation of outer solar system regolith, of these ices using the Mie scattering model and two other Hapke approximations (Hapke 1993) in radiative transfer scattering models (RTMs) at near-infrared (NIR) wavelengths (1–5 μm). The equivalent slab (Hapke slab) approximation model predicts results much closer to Mie scattering over the NIR wavelengths at a wide range …

Search For Gravitational Waves Associated With Gamma-Ray Bursts Detected By Fermi And Swift During The Ligo–Virgo Run O3b, Ligo Scientific Collaboration, Virgo Collaboration, Kagra Collaboration, Tiffany Z. Summerscales

Faculty Publications

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC–2020 March 27 17:00 UTC). We conduct two independent searches: a generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence …

Are Long-Period Exoplants Around Cool Stars More Common Than We Thought?, Emily Jane Safron

LSU Doctoral Dissertations

The Kepler mission has been the catalyst for discovery of nearly 5,000 confirmed and candidate exoplanets. The majority of these candidates orbit Sun-like stars, and have orbital periods comparable to or shorter than that of the Earth, due to the selection bias inherent in the transit method and the limitations of automated transit search algorithms. We aim to develop a richer understanding of the population of exoplanets around the lowest-mass stars, the M spectral type. We are particularly interested in exoplanets with long orbital periods, which are difficult or impossible to find using standard transit search algorithms. In our study, …