A Unified Binary Neutron Star Merger Magnetar Model For The Chandra X-Ray Transients Cdf-S Xt1 And Xt2,
2019
Chinese Academy of Sciences
A Unified Binary Neutron Star Merger Magnetar Model For The Chandra X-Ray Transients Cdf-S Xt1 And Xt2, Hui Sun, Ye Li, Bin-Bin Zhang, Bing Zhang, Franz E. Bauer, Yongquan Xue, Weimin Yuan
Physics & Astronomy Faculty Research
Two bright X-ray transients were reported from the Chandra Deep Field South (CDF-S) archival data, namely CDF-S XT1 and XT2. Whereas the nature of the former is not identified, the latter was suggested as an excellent candidate for a rapidly spinning magnetar born from a binary neutron star (BNS) merger. Here we propose a unified model to interpret both transients within the framework of the BNS merger magnetar model. According to our picture, CDF-S XT2 is observed from the "free zone" where the magnetar spindown powered X-ray emission escapes freely, whereas CDF-S XT1 originates from the "trapped zone" where the …
Tidal Destruction In A Low-Mass Galaxy Environment: The Discovery Of Tidal Tails Around Ddo 44,
2019
LSST and Steward Observatory
Tidal Destruction In A Low-Mass Galaxy Environment: The Discovery Of Tidal Tails Around Ddo 44, Jeffrey Carlin, Christopher Garling, Annika Peter, Denija Crnojević, Duncan Forbes, Jonathan Hargis, Burçin Mutlu-Pakdil, Ragadeepika Pucha, Aaron Romanowsky, David Sand, Kristine Spekkens, Jay Strader, Beth Willman
Faculty Publications
We report the discovery of a 1° (~50 kpc) long stellar tidal stream emanating from the dwarf galaxy DDO 44, a likely satellite of Local Volume galaxy NGC 2403 located ~70 kpc in projection from its companion. NGC 2403 is a roughly Large Magellanic Cloud (LMC) stellar-mass galaxy 3 Mpc away, residing at the outer limits of the M81 group. We are mapping a large region around NGC 2403 as part of our Magellanic Analogs' Dwarf Companions and Stellar Halos survey, reaching point-source depths (90% completeness) of (g, i) = (26.5, 26.2). Density maps of old, metal-poor RGB stars reveal …
A Hubble Pancet Study Of Hat-P-11b: A Cloudy Neptune With A Low Atmospheric Metallicity,
2019
California Institute of Technology
A Hubble Pancet Study Of Hat-P-11b: A Cloudy Neptune With A Low Atmospheric Metallicity, Yayaati Chachan, Heather A. Knutson, Peter Gao, Tiffany Kataria, Ian Wong, Gregory W. Henry, Bjorn Benneke, Michael Zhang, Joanna Barstow, Jacob L. Bean, Thomas Mikal-Evans, Nikole K. Lewis, Megan Mansfield, Mercedes López-Morales, Nikolay Nikolov, David K. Sing, Hannah Wakeford
Information Systems and Engineering Management Research Publications
We present the first comprehensive look at the 0.35–5 μm transmission spectrum of the warm (∼800 K) Neptune HAT-P-11b derived from 13 individual transits observed using the Hubble and Spitzer Space Telescopes. Along with the previously published molecular absorption feature in the 1.1–1.7 μm bandpass, we detect a distinct absorption feature at 1.15 μm and a weak feature at 0.95 μm, indicating the presence of water and/or methane with a combined significance of 4.4σ. We find that this planet's nearly flat optical transmission spectrum and attenuated near-infrared molecular absorption features are best matched by models incorporating a high-altitude cloud layer. …
Search For Gravitational-Wave Signals Associated With Gamma-Ray Bursts During The Second Observing Run Of Advanced Ligo And Advanced Virgo,
2019
Andrews University
Search For Gravitational-Wave Signals Associated With Gamma-Ray Bursts During The Second Observing Run Of Advanced Ligo And Advanced Virgo, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration
Faculty Publications
We present the results of targeted searches for gravitational-wave transients associated with gamma-ray bursts during the second observing run of Advanced LIGO and Advanced Virgo, which took place from 2016 November to 2017 August. We have analyzed 98 gamma-ray bursts using an unmodeled search method that searches for generic transient gravitational waves and 42 with a modeled search method that targets compact-binary mergers as progenitors of short gamma-ray bursts. Both methods clearly detect the previously reported binary merger signal GW170817, with p-values of <9.38 × 10−6 (modeled) and 3.1 × 10−4 (unmodeled). We do not find any significant evidence for …
Meps Data Assimilation System,
2019
Center for Atmospheric and Space Sciences, Utah State University
Meps Data Assimilation System, Robert W. Schunk, Larry Gardner
Browse all Datasets
For the current funding opportunity we propose to develop a master system that will enhance the user interface to the MEPS model and enable the scientific community to efficiently use the model. Furthermore, we will build and automate validation tools and improve the efficiency and robustness of the MEPS ensemble averaging scheme. Finally, we will explore the nest step toward a major advancement in MEPS b significantly improving the spatial resolution of one of the data assimilation models to explore meso- and small-scale features.
Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1,
2019
Andrews University
Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration
Faculty Publications
The detection of gravitational waves by Advanced LIGO and Advanced Virgo provides an opportunity to test general relativity in a regime that is inaccessible to traditional astronomical observations and laboratory tests. We present four tests of the consistency of the data with binary black hole gravitational waveforms predicted by general relativity. One test subtracts the best-fit waveform from the data and checks the consistency of the residual with detector noise. The second test checks the consistency of the low- and high-frequency parts of the observed signals. The third test checks that phenomenological deviations introduced in the waveform model (including in …
Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1,
2019
The University of Texas Rio Grande Valley
Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1, B. P. Abbott, S. Mukherjee
Physics & Astronomy Faculty Publications
The detection of gravitational waves by Advanced LIGO and Advanced Virgo provides an opportunity to test general relativity in a regime that is inaccessible to traditional astronomical observations and laboratory tests. We present four tests of the consistency of the data with binary black hole gravitational waveforms predicted by general relativity. One test subtracts the best-fit waveform from the data and checks the consistency of the residual with detector noise. The second test checks the consistency of the low- and high-frequency parts of the observed signals. The third test checks that phenomenological deviations introduced in the waveform model (including in …
Morphological Signatures Induced By Dust Back Reactions In Discs With An Embedded Planet,
2019
University of Nevada, Las Vegas
Morphological Signatures Induced By Dust Back Reactions In Discs With An Embedded Planet, Chao-Chin Yang, Zhaohuan Zhu
Physics & Astronomy Faculty Research
Recent observations have revealed a gallery of substructures in the dust component of nearby protoplanetary discs, including rings, gaps, spiral arms, and lopsided concentrations. One interpretation of these substructures is the existence of embedded planets. Not until recently, however, most of the modelling effort to interpret these observations ignored the dust back reaction to the gas. In this work, we conduct local-shearing-sheet simulations for an isothermal, inviscid, non-self-gravitating, razor-thin dusty disc with a planet on a fixed circular orbit. We systematically examine the parameter space spanned by planet mass (0.1Mth ≤ Mp ≤ 1Mth, where Mth is the thermal mass), …
Wasp-52b. The Effect Of Star-Spot Correction On Atmospheric Retrievals,
2019
INAF – Catania Astrophysical Observatory
Wasp-52b. The Effect Of Star-Spot Correction On Atmospheric Retrievals, Giovanni Bruno, Nikole K. Lewis, Munazza K. Alam, Mercedes López-Morales, Joanna K. Barstow, Hannah R. Wakeford, David K. Sing, Gregory W. Henry, Gilda E. Ballester, Vincent Bourrier, Lars A. Buchhave, Ofer Cohen, Thomas Mikal-Evans, Antonio García Muñoz, Panayotis Lavvas, Jorge Sanz-Forcada
Information Systems and Engineering Management Research Publications
We perform atmospheric retrievals on the full optical to infrared (0.3−5μm) transmission spectrum of the inflated hot Jupiter WASP-52b by combining HST/STIS, WFC3 IR, and Spitzer/IRAC observations. As WASP-52 is an active star that shows both out-of-transit photometric variability and star-spot crossings during transits, we account for the contribution of non-occulted active regions in the retrieval. We recover a 0.1–10× solar atmospheric composition, in agreement with core accretion predictions for giant planets, and no significant contribution of aerosols. We also obtain a star-spots, a measure which is likely affected by the models used to fit instrumental effects in …
Graded Quivers, Generalized Dimer Models And Toric Geometry,
2019
CUNY Graduate Center
Graded Quivers, Generalized Dimer Models And Toric Geometry, Sebastián Franco, Azeem Hasan
Publications and Research
The open string sector of the topological B-model on CY (m+2)-folds is described by m-graded quivers with superpotentials. This correspondence extends to general m the well known connection between CY (m+2)-folds and gauge theories on the world-volume of D(5-2m)-branes for m = 0, ..., 3. We introduce m-dimers, which fully encode the m-graded quivers and their superpotentials, in the case in which the CY (m+2)-folds are toric. Generalizing the well known m = 1,2 cases, m-dimers significantly simplify the connection between geometry and m-graded quivers. A key …
Measurements Of The 16c + 12c And 16c + 13c Fusion Cross Sections With Implications For Astrophysics,
2019
Texas A & M University - College Station
Measurements Of The 16c + 12c And 16c + 13c Fusion Cross Sections With Implications For Astrophysics, Ashley Ann Hood
LSU Doctoral Dissertations
The fusion of neutron-rich nuclei is of interest to nuclear astrophysics and nuclear structure. X-ray superbursts are powered by runaway thermonuclear burning deep inside of a neutron star, where heating from the pycnonuclear fusion of neutron-rich isotopes is an important heat source. Experimental measurements of fusion cross sections of neutron-rich isotopes have provided insights regarding nucleon transfer and nuclear structure properties affecting fusion. Recently, the 15C + 12C total fusion cross section was measured using a 15C beam produced by the in-flight beam production facility, which is part of the Argonne Tandem LINAC Accelerator System (ATLAS) at …
The Halo Mass Function Of Late-Type Galaxies From H I Kinematics,
2019
Case Western Reserve University
The Halo Mass Function Of Late-Type Galaxies From H I Kinematics, Pengfei Li, Stacy S. Mcgaugh
Faculty Scholarship
We present an empirical method to measure the halo mass function (HMF) of galaxies. We determine the relation between the H i line width from single-dish observations and the dark matter halo mass (M 200) inferred from rotation-curve fits in the Spitzer Photometry and Accurate Rotation Curves (SPARC) database, then we apply this relation to galaxies from the H i Parkes All Sky Survey (HIPASS) to derive the HMF. This empirical HMF is well fit by a Schechter function, and matches that expected in the Λ Cold Dark Matter (ΛCDM) model over the range 1010.5 < M 200 < 1012 M o˙. More massive halos must be poor in neutral gas to maintain consistency with the power law predicted by ΛCDM. We detect no discrepancy at low masses. The lowest halo mass probed by HIPASS, however, is just greater than the mass scale where the Local Group missing satellite problem sets in. The integrated mass density associated with the dark matter halos of H i-detected galaxies sums to Ωm,gal ≈ 0.03 over the probed mass range.
Using Natural Phenomena To Study The Ionosphere,
2019
University of New Mexico - Main Campus
Using Natural Phenomena To Study The Ionosphere, Joseph Benjamin Malins
Physics & Astronomy ETDs
This dissertation explores novel techniques for observing the ionosphere using natural signals. The ionosphere is a region of plasma hundreds of kilometers above the Earth that affects communication and remote sensing applications across the world. Traditional techniques for observing the ionosphere involve using man made radio signals, either to reflect the signal at HF frequencies or to pass several signals through the ionosphere and compare the difference the ionosphere makes in the signals. However, such techniques are limited by the ability of equipment to produce these signals and by the numerous laws and regulations governing transmission of signals in the …
Realistic Sensitivity Curves For Pulsar Timing Arrays,
2019
The University of Texas Rio Grande Valley
Realistic Sensitivity Curves For Pulsar Timing Arrays, Jeffrey S. Hazboun, Joseph D. Romano, Tristan L. Smith
Physics & Astronomy Faculty Publications
We construct realistic sensitivity curves for pulsar timing array searches for gravitational waves, incorporating both red and white noise contributions to individual pulsar noise spectra, and the effect of fitting to a pulsar timing model. We demonstrate the method on both simulated pulsars and a realistic array consisting of a subset of NANOGrav pulsars used in recent analyses. A comparison between the results presented here and measured upper limit curves from actual analyses shows agreement to tens of percent. The resulting sensitivity curves can be used to assess the detectability of predicted gravitational-wave signals in the nanohertz frequency band in …
Evolution Of A Relativistic Electron Beam For Tracing Magnetospheric Field Lines,
2019
Princeton University
Evolution Of A Relativistic Electron Beam For Tracing Magnetospheric Field Lines, Andrew T. Powis, Peter Porazik, Michael Greklek-Mckeon, Kailas Amin, David Shaw, Igor D. Kaganovich, Jay R. Johnson, Ennio Sanchez
Faculty Publications
Tracing magnetic field-lines of the Earth's magnetosphere using beams of relativistic electrons will open up new insights into space weather and magnetospheric physics. Analytic models and a single-particle-motion code were used to explore the dynamics of an electron beam emitted from an orbiting satellite and propagating until impact with the Earth. The impact location of the beam on the upper atmosphere is strongly influenced by magnetospheric conditions, shifting up to several degrees in latitude between different phases of a simulated storm. The beam density cross-section evolves due to cyclotron motion of the beam centroid and oscillations of the beam envelope. …
Electromagnetic Analysis Of Bidirectional Reflectance From Roughened Surfaces And Applications To Surface Shape Recovery,
2019
University of New Mexico
Electromagnetic Analysis Of Bidirectional Reflectance From Roughened Surfaces And Applications To Surface Shape Recovery, Julian Antolin Camarena
Physics & Astronomy ETDs
Scattering from randomly rough surfaces is a well-established sub area of electrodynamics. There remains much to be done since each surface and optical processes that may occur in within the scattering medium, and countless other scenarios, is different. There are also illumination models that describe lighting in a scene on the macroscopic scale where geometrical optics can be considered adequate. Of particular interest for us is the intersection of the physical scattering theories and the illumination models. We present two contributions: 1) A minimum of two independent images are needed since any opaque surface can be uniquely specified in terms …
Secondary Infall In The Seyfert's Sextet: A Plausible Way Out Of The Short Crossing Time Paradox,
2019
University of North Dakota
Secondary Infall In The Seyfert's Sextet: A Plausible Way Out Of The Short Crossing Time Paradox, Omar López-Cruz, Héctor Javier Ibarra-Medel, Sebastián F. Sánchez, Mark Birkinshaw, Christopher Añorve, Jorge K. Barrera-Ballesteros, Jesús Falcon-Barroso, Wayne A. Barkhouse, Juan P. Torres-Papaqui
Physics Faculty Publications
We used integral field spectroscopy from CALIFA DR3 and multiwavelength publicly available data to investigate the star formation histories of galaxies in the Seyfert's Sextet (SS; HCG 79). The galaxies H79a, H79b, H79c, and H79f have low star formation rates despite showing strong signs of interaction. By exploring their individual specific star formation histories, we identified three earlier episodes of strong star formation common to these four galaxies. We use the last two episodes as markers of the epochs when the galaxies were crossing. We suggest that after the first turnaround, initially gas-rich galaxies crossed for the first time, consuming …
High Power And Optomechanics In Advanced Ligo Detectors,
2019
Louisiana State University and Agricultural and Mechanical College
High Power And Optomechanics In Advanced Ligo Detectors, Terra Christine Hardwick
LSU Doctoral Dissertations
In September 2015, a new era of astronomy began with the first direct detection of grav- itational waves from a binary black hole coalescence. The event was captured by the Laser Interferometer Gravitational-wave Observatory, comprised of two long-baseline interferometers, one in Livingston, LA and one in Hanford, WA. At the time of the first detection, the interferometers were part way through an upgrade to an advanced configuration and were operating with a strain sensitivity of just better than 10−23/Hz1/2 around 100Hz. The full Advanced LIGO design calls for sensitivity of a few parts in 10−24/Hz …
Alpha Capture Reaction Rates For Nucleosynthesis Within An Ab Initio Framework,
2019
Louisiana State University and Agricultural and Mechanical College
Alpha Capture Reaction Rates For Nucleosynthesis Within An Ab Initio Framework, Alison Constance Dreyfuss
LSU Doctoral Dissertations
Clustering in nuclear systems has broad impacts on all phases of stellar burning, and plays a significant role in our understanding of nucleosynthesis, or how and where nuclei are produced in the universe. The role of alpha particles in particular is extremely important for nuclear astrophysics: 4He was one of the earliest elements produced in the Big Bang, it is one of the most abundant elements in the universe, and helium burning -- in particular, the triple-alpha process -- is one of the most important ``engines'' in stars. To better understand nucleosynthesis and stellar burning, then, it is important …
Millimeter-Wavelength Characterization Of The Co Emission Of Comets 174p/Echeclus, 29p/Schwassmann-Wachmann, And C/2016 R2 (Panstarrs),
2019
University of South Florida
Millimeter-Wavelength Characterization Of The Co Emission Of Comets 174p/Echeclus, 29p/Schwassmann-Wachmann, And C/2016 R2 (Panstarrs), Kacper Wierzchos
USF Tampa Graduate Theses and Dissertations
Comets are fascinating minor solar system bodies. They contain some of the most pristine and unprocessed material found in the solar system. As a comet approaches the Sun it displays the characteristic cometary coma and tail. This is due to the release of volatile species through a variety of processes. In the present work I studied the carbon monoxide emission of three very unique comets; 174P/Echeclus, 29P/Schwassmann-Wachmann and C/2016 R2 (PanSTARRS) with different radio telescopes at millimeter wavelengths. After molecular hydrogen, carbon monoxide is the second most abundant molecule in the universe, and is also the most volatile of the …
