Physical Sciences and Mathematics Commons^™

Search For Continuous Gravitational Waves From 20 Accreting Millisecond X-Ray Pulsars In O3 Ligo Data, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Results are presented of searches for continuous gravitational waves from 20 accreting millisecond x-ray pulsars with accurately measured spin frequencies and orbital parameters, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. The search algorithm uses a hidden Markov model, where the transition probabilities allow the frequency to wander according to an unbiased random walk, while the J-statistic maximum-likelihood matched filter tracks the binary orbital phase. Three narrow subbands are searched for each target, centered on harmonics of the measured spin frequency. The search yields 16 candidates, consistent with a false alarm probability of …

On The Horizon: Nanosatellite Constellations Will Revolutionize The Internet Of Things (Iot), Diane Janosek

Seattle Journal of Technology, Environmental, & Innovation Law

The Internet of Things has experienced exponential growth and use across the globe with 25.1 billion devices currently in use. Until recently, the functionality of the IoT was dependent on secure data flow between internet terrestrial stations and the IoT devices. Now, a new alternative path of data flow is on the horizon.

IoT device manufacturers are now looking to outer space nanosatellite constellations to connect to a different type of internet. This new internet is no longer terrestrial with fiber cables six feet underground but now looking up, literally, 200 to 300 miles above the earth, to communicate, connect …

Search For Continuous Gravitational Waves From 20 Accreting Millisecond X-Ray Pulsars In O3 Ligo Data, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, C. Adams, Teviet Creighton, Mario C. Diaz, F. Llamas, Soma Mukherjee, Volker Quetschke, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

Results are presented of searches for continuous gravitational waves from 20 accreting millisecond x-ray pulsars with accurately measured spin frequencies and orbital parameters, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. The search algorithm uses a hidden Markov model, where the transition probabilities allow the frequency to wander according to an unbiased random walk, while the J-statistic maximum-likelihood matched filter tracks the binary orbital phase. Three narrow subbands are searched for each target, centered on harmonics of the measured spin frequency. The search yields 16 candidates, consistent with a false alarm probability of …

Detection Of Ongoing Mass Loss From Hd 63433c, A Young Mini-Neptune, Michael Zhang, Heather A. Knutson, Lile Wang, Fei Dai, Leonardo A. Dos Santos, Luca Fossati, Gregory W. Henry, David Ehrenreich, Yann Alibert, Sergio Hoyer, Thomas G. Wilson, Andrea Bonfanti

Information Systems and Engineering Management Research Publications

We detect Lyα absorption from the escaping atmosphere of HD 63433c, a R = 2.67R_⊕, P = 20.5 day mini-Neptune orbiting a young (440 Myr) solar analog in the Ursa Major Moving Group. Using Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph, we measure a transit depth of 11.1 ± 1.5% in the blue wing and 8 ± 3% in the red. This signal is unlikely to be due to stellar variability, but should be confirmed by an upcoming second transit observation with HST. We do not detect Lyα absorption from the inner planet, a smaller …

Search For Continuous Gravitational Waves From 20 Accreting Millisecond X-Ray Pulsars In O3 Ligo Data, Ligo Scientific Collaboration, Virgo Collaboration, Kagra Collaboration, Tiffany Z. Summerscales

Faculty Publications

Results are presented of searches for continuous gravitational waves from 20 accreting millisecond x-ray pulsars with accurately measured spin frequencies and orbital parameters, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. The search algorithm uses a hidden Markov model, where the transition probabilities allow the frequency to wander according to an unbiased random walk, while the J-statistic maximum-likelihood matched filter tracks the binary orbital phase. Three narrow subbands are searched for each target, centered on harmonics of the measured spin frequency. The search yields 16 candidates, consistent with a false alarm probability of …

Coupling Between Alfvén Wave And Kelvin–Helmholtz Waves In The Low Latitude Boundary Layer, Eun-Hwa Kim, Jay R. Johnson

Faculty Publications

The Kelvin–Helmholtz (KH) instability of magnetohydrodynamic surface waves at the low latitude boundary layer is examined using both an eigenfrequency analysis and a time-dependent wave simulation. The analysis includes the effects of sheared flow and Alfvén velocity gradient. When the magnetosheath flows are perpendicular to the ambient magnetic field direction, unstable KH waves that propagate obliquely to the sheared flow direction occur at the sheared flow surface when the Alfvén Mach number is higher than an instability threshold. Including a shear transition layer between the magnetosphere and magnetosheath leads to secondary KH waves (driven by the sheared flow) that are …

Comparison Of Maximum-Likelihood Mapping Methods For Gravitational-Wave Backgrounds, Arianna I. Renzini, Joseph D. Romano, Carlo R. Contaldi, Neil Cornish

Physics and Astronomy Faculty Publications and Presentations

Detection of a stochastic background of gravitational waves is likely to occur in the next few years. Beyond searches for the isotropic component of a stochastic gravitational-wave background, there have been various mapping methods proposed to target anisotropic backgrounds. Some of these methods have been applied to data taken by the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo. Specifically, these directional searches have focused on mapping the intensity of the signal on the sky via maximum-likelihood solutions. We compare this intensity mapping approach to a previously proposed, but never employed, amplitude-phase mapping method to understand whether this latter approach may …

Towards A Quantum Notion Of Covariance In Spherically Symmetric Loop Quantum Gravity, Rodolfo Gambini, Javier Olmedo, Jorge Pullin

Faculty Publications

The covariance of loop quantum gravity studies of spherically symmetric space-times has recently been questioned. This is a reasonable worry, given that they are formulated in terms of slicing-dependent variables. We show explicitly that the resulting space-times, obtained from Dirac observables of the quantum theory, are covariant in the usual sense of the way-they preserve the quantum line element-for any gauge that is stationary (in the exterior, if there is a horizon). The construction depends crucially on the details of the Abelianized quantization considered, the satisfaction of the quantum constraints, and the recovery of standard general relativity in the classical …

Towards A Quantum Notion Of Covariance In Spherically Symmetric Loop Quantum Gravity, Rodolfo Gambini, Javier Olmedo, Jorge Pullin

Faculty Publications

The covariance of loop quantum gravity studies of spherically symmetric space-times has recently been questioned. This is a reasonable worry, given that they are formulated in terms of slicing-dependent variables. We show explicitly that the resulting space-times, obtained from Dirac observables of the quantum theory, are covariant in the usual sense of the way-they preserve the quantum line element-for any gauge that is stationary (in the exterior, if there is a horizon). The construction depends crucially on the details of the Abelianized quantization considered, the satisfaction of the quantum constraints, and the recovery of standard general relativity in the classical …

Dr. Jennifer Hoffman, Anit Tyagi

DU Undergraduate Research Journal Archive

An interview with Dr. Jennifer Hoffman.

Dark And Quiet Skies Ii Working Group Reports:, James Lowenthal, Connie Walker, Piero Benvenuti

Astronomy: Faculty Publications

This Report presents the main results of the Conference “Dark and Quiet Skies for Science and Society II” which took place on-line on 3–7 October 2021. This conference was the logical follow-up of the first one, organized as an on-line workshop with the same title on 5–9 October 2020. Both conferences were co-organized by UNOOSA, IAU and the Government of Spain and were well attended. The focus of the second conference was about the feasibility of implementing the recommendations presented by the first one in its extensive report. The main qualifying difference between the first and the second conferences was …

Measurements Of The Electron-Helicity Asymmetry In The Quasi-Elastic A ((E) Over Right Arrow, E' O) Process, T. Kolar, S. J. Paul, P. Achenbach, H. Arenhoevel, A. Ashkenazi, J. Beričič, R. Böhm, D. Bosnar, T. Brecelj, E. Cline, E. O. Cohen, M. O. Distler, A. Esser, I. Friščić, R. Gilman, C. Giusti, M. Heilig, M. Hoek, D, Izraeli, Steffen Strauch, Et. Al.

Faculty Publications

We present measurements of the electron helicity asymmetry in quasi-elastic proton knockout from ²H and ¹²C nuclei by polarized electrons. This asymmetry depends on the fifth structure function, is antisymmetric with respect to the scattering plane, and vanishes in the absence of final-state interactions, and thus it provides a sensitive tool for their study. Our kinematics cover the full range in off-coplanarity angle θ_pq, with a polar angle θ_pq coverage up to about 8^◦. The missing energy resolution enabled us to determine the asymmetries for knock-out resulting in different states of the residual …

Deep Extragalactic Visible Legacy Survey: Data Release 1 Blended Spectra Search For Candidate Strong Gravitational Lenses, Benne Holwerda, S Knabel, J E. Thorne, S Bellstedt, M Siudek, L J M Davies

Faculty and Staff Scholarship

Here, we present a catalogue of blended spectra in Data Release 1 of the Deep Extragalactic VIsible Legacy Survey (DEVILS) on the Anglo-Australian Telescope. Of the 23 197 spectra, 181 showed signs of a blend of redshifts and spectral templates. We examine these blends in detail for signs of either a candidate strong lensing galaxy or a useful overlapping galaxy pair. One of the three DEVILS target fields, COSMOS (D10), is close to complete and it is fully imaged with Hubble Space Telescope Advanced Camera for Surveys, and we visually examine the 57 blended spectra in this field in the …

Design, Construction And Operation Of The Protodune-Sp Liquid Argon Tpc, The Dune Collaboration, A. Abed Abud, B. Abi, R. Acciarri, M. A. Acero, M. R. Adames, G. Adamov, D. Adams, M. Adinolfi, A. Aduszkiewicz, J. Aguilar, Z. Ahmad, J. Ahmed, B. Ali-Mohammadzadeh, T. Alion, K. Allison, S. Alonso Monsalve, M. Alrashed, C. Alt, A. Alton, Roberto Petti, Et. Al.

Faculty Publications

The ProtoDUNE-SP detector is a single-phase liquid argon time projection chamber (LArTPC) that was constructed and operated in the CERN North Area at the end of the H4 beamline. This detector is a prototype for the first far detector module of the Deep Underground Neutrino Experiment (DUNE), which will be constructed at the Sandford Underground Research Facility (SURF) in Lead, South Dakota, U.S.A. The ProtoDUNE-SP detector incorporates full-size components as designed for DUNE and has an active volume of 7 × 6 × 7.2 m³. The H4 beam delivers incident particles with well-measured momenta and high-purity particle identification. …

Individual Element Sensitivity For Stellar Evolutionary Isochrones, Guy Worthey, Xiang Shi, Tathagata Pal, Hyun-Chul Lee, Baitian Tang

Physics and Astronomy Faculty Publications and Presentations

Stellar evolution calculations with variable abundance ratios were used to gauge the effects on temperatures, luminosities, and lifetimes in various phases. The individual elements C, N, O, Mg, Si, and Fe were included. Most of the effect relevant to integrated light models is contained in the temperature variable, as opposed to the time-scale or luminosity. We derive a recipe for including abundance-sensitive temperature effects that is applicable to existing isochrone grids. The resultant enhanced isochrones are incorporated into composite stellar population models and compared with galaxy data from the Sloan Digital Sky Survey. A severe oxygen–age degeneracy is apparent, 2–3 …

Testing Effects Of Lorentz Invariance Violation In The Propagation Of Astroparticles With The Pierre Auger Observatory, P. Abreu, M. Aglietta, J. M. Albury, I. Allekotte, K. Almeida Cheminant

Faculty Publications

Lorentz invariance violation (LIV) is often described by dispersion relations of the form E-i(2) = m(i)(2) + p(i)(2) + delta E-i,n(2+ n) with delta different based on particle type i, with energy E, momentum p and rest mass m. Kinematics and energy thresholds of interactions are modified once the LIV terms become comparable to the squared masses of the particles involved. Thus, the strongest constraints on the LIV coefficients delta(i,n) tend to come from the highest energies. At sufficiently high energies, photons produced by cosmic ray interactions as they propagate through the Universe could be subluminal and unattenuated over cosmological …

Extremely Broad Ly Α Line Emission From The Molecular Intragroup Medium In Stephan's Quintet: Evidence For A Turbulent Cascade In A Highly Clumpy Multiphase Medium?, P. Guillard, P. N. Appleton, F. Boulanger, J. M. Shull, M. D. Lehnert, G. Pineau Des Forets, E. Falgarone, M. E. Cluver, C. K. Xu, Sarah C. Gallagher, P. A. Duc

Physics and Astronomy Publications

We present Hubble Space Telescope Cosmic Origin Spectrograph (COS) UV line spectroscopy and integral-field unit (IFU) observations of the intragroup medium in Stephan's Quintet (SQ). SQ hosts a 30 kpc long shocked ridge triggered by a galaxy collision at a relative velocity of 1000 km s-1, where large amounts of molecular gas coexist with a hot, X-ray-emitting, plasma. COS spectroscopy at five positions sampling the diverse environments of the SQ intragroup medium reveals very broad (≈2000 km s-1) Lyα line emission with complex line shapes. The Lyα line profiles are similar to or much broader than those of Hβ, [C …

Bending Waves Excited By Irregular Gas Inflow Along Warps, Tigran Khachaturyants, Leandro Beraldo E Silva, Victor P. Debattista, Kathryne J. Daniel

Physics Faculty Research and Scholarship

Gaia has revealed clear evidence of bending waves in the vertical kinematics of stars in the solar neighbourhood. We study bending waves in two simulations, one warped, with the warp due to misaligned gas inflow, and the other unwarped. We find slow, retrograde bending waves in both models, with the ones in the warped model having larger amplitudes. We also find fast, prograde bending waves. Prograde bending waves in the unwarped model are very weak, in agreement with the expectation that these waves should decay on short, approximately crossing, time-scales, due to strong winding. However, prograde bending waves are much …

Performance Of Near-Infrared High-Contrast Imaging Methods With Jwst From Commissioning, Jens Kammerer, Julien Girard, Aarynn L. Carter, Marshall D. Perrin, Rachel Cooper, Deepashri Thatte, Thomas Vandal, Jarron Leisenring, Jason Wang, William O. Balmer, Anand Sivaramakrishnan, Laurent Pueyo, Kimberly Ward-Duong, Ben Sunnquist, Jéa Adams Redai

Astronomy: Faculty Publications

The James Webb Space Telescope (JWST) will revolutionize the field of high-contrast imaging and enable both the direct detection of Saturn-mass planets and the characterization of substellar companions in the mid-infrared. While JWST will feature unprecedented sensitivity, angular resolution will be the key factor when competing with ground-based telescopes. Here, we aim to characterize the performance of several extreme angular resolution imaging techniques available with JWST in the 3-5 µm regime based on data taken during the instrument commissioning. Firstly, we introduce custom tools to simulate, reduce, and analyze JWST NIRCam and MIRI coronagraphy data and use these tools to …

Direct Imaging & Spectroscopy Of Exoplanetary Systems With The Jwst Early Release Science Program, Sasha Hinkley, Aarynn L. Carter, Shrishmoy Ray, Beth Biller, Andrew Skemer, Elodie Choquet, Maxwell A. Millar-Blanchaer, Stephanie Sallum, Brittany Miles, Niall Whiteford, Polychronis Patapis, Marshall Perrin, Laurent Pueyo, Karl Stapelfeldt, Jason Wang, Kimberly Ward-Duong, Julien H. Girard, Dean Hines, Jens Kammerer, Jarron Leisenring, Yifan Zhou, Michael Meyer, Michael C. Liu, Mickael Bonnefoy, Simon Petrus, Mariangela Bonavita, Gael Chauvin, Christine Chen, Thayne Currie, Kielan K.W. Hoch, Cecilia Lazzoni, Elisabeth C. Matthews

Astronomy: Faculty Publications

The direct characterization of exoplanetary systems with high contrast imaging is among the highest priorities for the broader exoplanet community. As large space missions will be necessary for detecting and characterizing exo-Earth twins, developing the techniques and technology for direct imaging of exoplanets is a driving focus for the community. For the first time, JWST will directly observe extrasolar planets at mid-infrared wavelengths beyond 5 μm, deliver detailed spectroscopy revealing much more precise chemical abundances and atmospheric conditions, and provide sensitivity to analogs of our solar system ice-giant planets at wide orbital separations, an entirely new class of exoplanet. However, …

Study Of B ¯ 0 →D+H- (H=K/Π) Decays At Belle Study Of B ¯ 0 →D+H- (H=K/Π) ... Waheed E. Et Al., E. Waheed, P. Urquijo, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, S. Bahinipati, P. Behera, K. Belous, J. Bennett, M. Bessner, V. Bhardwaj, B. Bhuyan, T. Bilka, J. Biswal, A. Bobrov

Faculty and Student Publications

We present a measurement of the branching fractions of the Cabibbo favored B¯0→D+π- and the Cabibbo suppressed B¯0→D+K- decays. We find B(B¯0→D+π-)=(2.48±0.01±0.09±0.04)×10-3 and B(B¯0→D+K-)=(2.03±0.05±0.07±0.03)×10-4 decays, where the first uncertainty is statistical, the second is systematic, and the third uncertainty is due to the D+→K-π+π+ branching fraction. The ratio of branching fractions of B¯0→D+K- and B¯0→D+π- is measured to be RD=[8.19±0.20(stat)±0.23(syst)]×10-2. These measurements are performed using the full Belle dataset, which corresponds to 772×106BB¯ pairs and use the Belle II software framework for data analysis.

Perturbative Unitarity And Nec Violation In Genesis Cosmology, Yong Cai, Ji Xu, Shuai Zhao, Siyi Zhou

Physics Faculty Publications

Explorations of the violation of null energy condition (NEC) in cosmology could enrich our understanding of the very early universe and the related gravity theories. Although a fully stable NEC violation can be realized in the “beyond Horndeski” theory, it remains an open question whether a violation of the NEC is allowed by some fundamental properties of UV-complete theories or the consistency requirements of effective field theory (EFT). We investigate the tree-level perturbative unitarity for stable NEC violations in the contexts of both Galileon and “beyond Horndeski” genesis cosmology, in which the universe is asymptotically Minkowskian in the past. We …

Information Entropic Content Of Astrophysical Spectra: Applications To Cosmology And Astrobiology, Sara Vannah

Dartmouth College Ph.D Dissertations

Astrophysics faces two critical challenges: the difficulty of observing very distant targets and the difficulty of interpreting science in diverse and often extreme environments that have not been replicated on Earth. In this thesis, we discuss two types of spectra — one from early universe cosmology and one from astrobiology — where improvements in telescope technology are just ushering in a wave of precise observations, addressing the first challenge. This accelerates the need for a solution to the second challenge. Traditional methods for analyzing these two spectra rely heavily on unsettled science, biasing results to match the input assumptions. In …

Biographical Calendars Of Astronomers [January - December], Thomas A. Hockey

Data Sets

A set of twelve biographical calendars of astronomers for each month of the year (January through December). History of astronomy (public outreach).

Record contents:

• Main Download button - A merged Excel file with all 12 months
• Additional Files section - Individual Excel files for each month [January - December]

Comparative Study Of High Order Methods For Subsonic Turbulence Simulation With Stochastic Forcing, Alexei G. Kritsuk, H. C. Yee, Björn Sjögreen, Dmitry Kotov

United States National Aeronautics and Space Administration: Publications

A class of spatially seventh-order nonlinear filter methods with adaptive dissipation control developed by Yee & Sjögreen [1, 2] is tested on three-dimensional subsonic turbulence simulations with stochastic forcing. The Euler equations are solved using the Strang operator splitting of the homogeneous part of the equations and the stochastic forcing term, with an ODE solver used to integrate the latter. Both Ducros et al. and Kennedy-Gruber skew-symmetric split formulations of the inviscid flux derivatives are considered to minimize the use of numerical dissipation. The nonlinear filter methods are shown to be numerically stable for this application at least up to …

A Combined Spectral And Energy Morphology Analysis Of Gamma Ray Source Hawc J2031+415 In The Cygnus Constellation, Ian Herzog

Dissertations, Master's Theses and Master's Reports

HAWC J2031+415 is a probable pulsar wind nebula (PWN) located in the Cygnus Cocoon region near a complex OB star cluster. First observed by the High-Energy-Gamma-Ray Astronomy (HEGRA) observatory in the TeV energy regime, the source had no apparent counterpart in lower energy ranges. Previous work using 1343 days of data from the High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory has determined that three sources are present in the Region of Interest (ROI): HAWC J2031+415, HAWC J2030+409 (also known as the Cocoon), and 3HWC J2020+403 (associated with the Gamma Cygni supernova remnant) \cite{Ian_01, Binita_01}.

In this work, I use the newest …

A Search For Analogs Of Kic 8462852 (Boyajian’S Star): A Second List Of Candidates, Edward G. Schmidt

Edward Schmidt Publications

In data from the Kepler mission, the normal F3V star KIC 8462852 (Boyajian’s star) was observed to exhibit infrequent dips in brightness that have not been satisfactorily explained. A previous paper reported the first results of a search for other similar stars in a limited region of the sky around the Kepler field. This paper expands on that search to cover the entire sky between declinations of +22°and +68°. Fifteen new candidates with low rates of dipping, referred to as “slow dippers” in Paper I, have been identified. The dippers occupy a limited region of the HR diagram and an …

Hidden Symmetries Of The Kepler Problem, Julia Kathryn Sheffler

Senior Projects Spring 2022

The orbits of planets can be described by solving Kepler’s problem which considers the motion due to by gravity (or any inverse square force law). The solutions to Kepler’s problem, for energies less then 0, are ellipses, with a few conserved quantities: energy, angular momentum and the Laplace-Runge-Lenz (LRL) vector. Each conserved quantity corresponds to symmetries of the system via N ̈other’s theorem. Energy conservation relates to time translations and angular momentum to three dimensional rotations. The symmetry related to the LRL vector is more difficult to visualize since it lives in phase space rather than configuration space. To understand …

Long-Term Rotational Evolution Of The Stis Ccd Flatfields, Kimberly Ward-Huong, S. Lockwood, J. Debes, R. J. De Rosa

Astronomy: Faculty Publications

We confirm a long-term rotational drift of 0.0031 degrees/year of the STIS CCD based upon analysis of 50CCD flatfields spanning over 20 years of calibration data. Using the dust motes present in the flatfields, we extract the positions of the motes in each image, allowing us to develop a catalog of stable, high ‘signal-to-noise’ mote features and track their relative positions over time. We find that the motes appear to be moving at the aforementioned rate relative to an approximate center of rotation located at X=468.02, Y=411.18 in detector pixel coordinates. Given the relatively large errors in centroiding the unusually-shaped …

Atmospheric Retrieval: Bayesian Methods, Machine Learning, And Application To Exoplanets, Michael Himes

Electronic Theses and Dissertations, 2020-2023

Atmospheric retrieval is the inverse modeling method where atmospheric properties are constrained based on measured spectra. Due to the low signal-to-noise ratios of exoplanet observations, exoplanetary retrieval codes pair a radiative transfer (RT) simulator with a Bayesian statistical framework in order to characterize the distribution of atmospheric parameters that could explain the observations (the posterior distribution). This requires on the order of 106 RT model evaluations, which requires hours to days of compute time depending on model complexity. In this work, I investigate atmospheric retrieval methods and apply them to observations of hot Jupiters. Chapter 2 presents a set of …