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University of Texas Rio Grande Valley

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Articles 271 - 300 of 832

Full-Text Articles in Astrophysics and Astronomy

Dna-Topology Simplification By Topoisomerases, Andreas Hanke, Riccardo Ziraldo, Stephen D. Levene Jun 2021

Dna-Topology Simplification By Topoisomerases, Andreas Hanke, Riccardo Ziraldo, Stephen D. Levene

Physics & Astronomy Faculty Publications

The topological properties of DNA molecules, supercoiling, knotting, and catenation, are intimately connected with essential biological processes, such as gene expression, replication, recombination, and chromosome segregation. Non-trivial DNA topologies present challenges to the molecular machines that process and maintain genomic information, for example, by creating unwanted DNA entanglements. At the same time, topological distortion can facilitate DNA-sequence recognition through localized duplex unwinding and longer-range loop-mediated interactions between the DNA sequences. Topoisomerases are a special class of essential enzymes that homeostatically manage DNA topology through the passage of DNA strands. The activities of these enzymes are generally investigated using circular DNA …

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Diving Below The Spin-Down Limit: Constraints On Gravitational Waves From The Energetic Young Pulsar Psr J0537-6910, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang Jun 2021

Diving Below The Spin-Down Limit: Constraints On Gravitational Waves From The Energetic Young Pulsar Psr J0537-6910, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang

Physics & Astronomy Faculty Publications

We present a search for quasi-monochromatic gravitational-wave signals from the young, energetic X-ray pulsar PSR J0537-6910 using data from the second and third observing runs of LIGO and Virgo. The search is enabled by a contemporaneous timing ephemeris obtained using Neutron star Interior Composition Explorer (NICER) data. The NICER ephemeris has also been extended through 2020 October and includes three new glitches. PSR J0537-6910 has the largest spin-down luminosity of any pulsar and exhibits fRequent and strong glitches. Analyses of its long-term and interglitch braking indices provide intriguing evidence that its spin-down energy budget may include gravitational-wave emission from a …

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Environmental Noise In Advanced Ligo Detectors, P. Nguyen, R. M. S. Schofield, A. Effler, C. Austin, V. B. Adya, M. Ball, S. Banagiri, K. Banowetz, C. Billman, Karla E. Ramirez Jun 2021

Environmental Noise In Advanced Ligo Detectors, P. Nguyen, R. M. S. Schofield, A. Effler, C. Austin, V. B. Adya, M. Ball, S. Banagiri, K. Banowetz, C. Billman, Karla E. Ramirez

Physics & Astronomy Faculty Publications

The sensitivity of the advanced LIGO detectors to gravitational waves can be affected by environmental disturbances external to the detectors themselves. Since the transition from the former initial LIGO phase, many improvements have been made to the equipment and techniques used to investigate these environmental effects. These methods have aided in tracking down and mitigating noise sources throughout the first three observing runs of the advanced detector era, keeping the ambient contribution of environmental noise below the background noise levels of the detectors. In this paper we describe the methods used and how they have led to the mitigation of …

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Fabrication Of Nd3+ And Yb3+ Doped Nir Emitting Nano Fluorescent Probe: A Candidate For Bioimaging Applications, D. Karthickraja, G. A. Kumar, D. K. Sardar, S. Karthi, Gamage C. Dannangoda, Karen S. Martirosyan, M. Prasath, M. Gowri, E. L. Girija Jun 2021

Fabrication Of Nd3+ And Yb3+ Doped Nir Emitting Nano Fluorescent Probe: A Candidate For Bioimaging Applications, D. Karthickraja, G. A. Kumar, D. K. Sardar, S. Karthi, Gamage C. Dannangoda, Karen S. Martirosyan, M. Prasath, M. Gowri, E. L. Girija

Physics & Astronomy Faculty Publications

The intentional design of rare earth doped luminescent architecture exhibits unique optical properties and it can be considered as a promising and potential probe for optical imaging applications. Calcium fluoride (CaF2) nanoparticles doped with optimum concentration of Nd3+ and Yb3+ as sensitizer and activator, respectively, were synthesized by wet precipitation method and characterized by x-ray diffraction (XRD) and photoluminescence. In spite of the fact that the energy transfer takes place from Nd3+ to Yb3+, the luminescence intensity was found to be weak due to the lattice defects generated from the doping of trivalent cations (Nd3+ and Yb3+) for divalent host …

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Approaching The Motional Ground State Of A 10-Kg Object, Chris Whittle, E. D. Hall, S. E. Dwyer, N. Mavalvala, Vivishek Sudhir, R. Abbott, A. Ananyeva, C. Austin, L. Barsotti, Karla E. Ramirez Jun 2021

Approaching The Motional Ground State Of A 10-Kg Object, Chris Whittle, E. D. Hall, S. E. Dwyer, N. Mavalvala, Vivishek Sudhir, R. Abbott, A. Ananyeva, C. Austin, L. Barsotti, Karla E. Ramirez

Physics & Astronomy Faculty Publications

The motion of a mechanical object— even a human-sized object— should be governed by the rules of quantum mechanics. Coaxing them into a quantum state is, however, difficult: the thermal environment effectively masks any quantum signature of the object’s motion. Indeed, it also masks effects of proposed modifications of quantum mechanics at large mass scales. We prepare the center-of-mass motion of a 10 kg mechanical oscillator in a state with an average phonon occupation of 10.8. The reduction in oscillator temperature, from room temperature to 77 nK, represents a 100-fold improvement in the reduction of temperature of a solid-state mechanical …

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Population Properties Of Compact Objects From The Second Ligo–Virgo Gravitational-Wave Transient Catalog, R. Abbott, T. D. Abbott, S. Abraham, Ofek Birnholtz, F. Acernese, Teviet Creighton, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, W. H. Wang May 2021

Population Properties Of Compact Objects From The Second Ligo–Virgo Gravitational-Wave Transient Catalog, R. Abbott, T. D. Abbott, S. Abraham, Ofek Birnholtz, F. Acernese, Teviet Creighton, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, W. H. Wang

Physics & Astronomy Faculty Publications

We report on the population of 47 compact binary mergers detected with a false-alarm rate of < in the second LIGO–Virgo Gravitational-Wave Transient Catalog. We observe several characteristics of the merging binary black hole (BBH) population not discernible until now. First, the primary mass spectrum contains structure beyond a power law with a sharp high-mass cutoff; it is more consistent with a broken power law with a break at or a power law with a Gaussian feature peaking at (90% credible interval). While the primary mass distribution must extend to or beyond, only of systems have primary masses greater than . Second, we find that a fraction of BBH systems have component spins misaligned with the orbital angular momentum, giving rise to precession of the orbital plane. Moreover, %–% of BBH systems have spins tilted by more than 90°, giving rise to a negative effective inspiral spin parameter, . Under the assumption that such systems can only be formed by dynamical interactions, we infer that between 25% and 93% of BBHs with nonvanishing are dynamically assembled. Third, we estimate merger rates, finding for BBHs and for binary neutron stars. We find that the BBH rate likely increases with redshift ( credibility) but not faster than the star formation rate ( credibility). Additionally, we examine recent exceptional events in the context of our population models, finding that the asymmetric masses of GW190412 and the high component masses of GW190521 are consistent with our models, but the low secondary mass of GW190814 makes it an outlier.

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Tidal Deformability Of Strange Stars And The Gw170817 Event, Odilon Lourenço, Cesar H. Lenzi, Mariana Dutra, Efrain J. Ferrer, Vivian De La Incera, Laura Paulucci, J. E. Horvath May 2021

Tidal Deformability Of Strange Stars And The Gw170817 Event, Odilon Lourenço, Cesar H. Lenzi, Mariana Dutra, Efrain J. Ferrer, Vivian De La Incera, Laura Paulucci, J. E. Horvath

Physics & Astronomy Faculty Publications

In this work we consider strange stars formed by quark matter in the color-flavor-locked (CFL) phase of color superconductivity. The CFL phase is described by a Nambu-Jona-Lasinio model with four-fermion vector and diquark interaction channels. The effect of the color superconducting medium on the gluons are incorporated into the model by including the gluon self-energy in the thermodynamic potential. We construct parametrizations of the model by varying the vector coupling GV and comparing the results to the data on tidal deformability from the GW170817 event, the observational data on maximum masses from massive pulsars such as the MSP J0740+6620, and …

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Study Of Efficient Methods Of Detection And Reconstruction Of Gravitational Waves From Nonrotating 3d General Relativistic Core Collapse Supernovae Explosion Using Multilayer Signal Estimation Method, Soma Mukherjee, Gaukhar Nurbek, Oscar Valdez May 2021

Study Of Efficient Methods Of Detection And Reconstruction Of Gravitational Waves From Nonrotating 3d General Relativistic Core Collapse Supernovae Explosion Using Multilayer Signal Estimation Method, Soma Mukherjee, Gaukhar Nurbek, Oscar Valdez

Physics & Astronomy Faculty Publications

In the post-detection era of gravitational wave (GW) astronomy, core collapse supernovae (CCSN) are one of the most interesting potential sources of signals arriving at the Advanced LIGO detectors. Mukherjee et al. have developed and implemented a new method to search for GW signals from the CCSN search based on a multistage, high accuracy spectral estimation to effectively achieve higher detection signal to noise ratio (SNR). The study has been further enhanced by incorporation of a convolutional neural network (CNN) to significantly reduce false alarm rates (FAR). The combined pipeline is termed multilayer signal estimation (MuLaSE) that works in an …

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Absolute Power Measurements For Advanced Ligo Photon Calibrator, Francisco Llamas Villarreal May 2021

Absolute Power Measurements For Advanced Ligo Photon Calibrator, Francisco Llamas Villarreal

Theses and Dissertations

Since its first detection in 2015, the Light Interferometer Gravitational-Wave Observatory has been notably recognized for the successful measurement of gravitational waves. The successful detection of gravitational-waves comes from the effort of more than a thousand scientist working in collaboration. To characterize the change in displacement of the ETMs, LIGO uses several methods of calibration. The Photon Calibrator has gained significance to the point of becoming the primary calibration tool for the Advanced LIGO detectors. Relying on photon radiation pressure to calibrate the interferometer, the photon calibrator measures the change in displacement of the ETM in relation to the power …

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Enhanced Detection Efficiencies And Reduced False Alarms In Searching For Gravitational Waves From Core Collapse Supernovae, Gaukhar Nurbek May 2021

Enhanced Detection Efficiencies And Reduced False Alarms In Searching For Gravitational Waves From Core Collapse Supernovae, Gaukhar Nurbek

Theses and Dissertations

A supernova is a star that flares up very suddenly and then slowly returns to its former luminosity or, explodes violently with energy $10^{52}$ erg. There are stars which are 10 times or more massive than the Sun, which usually end their lives going supernova. When there is no longer enough fuel for the fusion process in the core of the star and inward gravitational pull of the star’s great mass takes place, the star starts to explode. A series of nuclear reactions starts taking place after the star begins shrinking due to gravity. In the final phase of this …

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Automated Identification Of Lines In Data From Gravitational Wave Detectors, Thomas A. Cruz May 2021

Automated Identification Of Lines In Data From Gravitational Wave Detectors, Thomas A. Cruz

Theses and Dissertations

On the frontier of gravitational wave (GW) astronomy, the LIGO detectors record vast quantities of data that need to be analyzed constantly for rare and transient GW signals. A foundational problem in LIGO data analysis is the identification of spectral line features in the Power Spectral Density (PSD) of the data. Such line features correspond to high power terrestrial or instrumental signals that must be removed from the data before any search for GW signals can take place. In this study the method developed aims to automate the extraction of the frequencies and bandwidths of the lines, treated as sharp …

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Point Absorbers In Advanced Ligo, Aidan F. Brooks, Gabriele Vajente, Hiro Yamamoto, R. Abbott, C. Adams, R. Adhikari, A. Ananyeva, S. Appert, K. Arai, Karla E. Ramirez May 2021

Point Absorbers In Advanced Ligo, Aidan F. Brooks, Gabriele Vajente, Hiro Yamamoto, R. Abbott, C. Adams, R. Adhikari, A. Ananyeva, S. Appert, K. Arai, Karla E. Ramirez

Physics & Astronomy Faculty Publications

Small, highly absorbing points are randomly present on the surfaces of the main interferometer optics in Advanced LIGO. The resulting nanometer scale thermo-elastic deformations and substrate lenses from these micronscale absorbers significantly reduce the sensitivity of the interferometer directly though a reduction in the power-recycling gain and indirect interactions with the feedback control system. We review the expected surface deformation from point absorbers and provide a pedagogical description of the impact on power buildup in second generation gravitational wave detectors (dual-recycled Fabry-Perot Michelson interferometers). This analysis predicts that the power-dependent reduction in interferometer performance will significantly degrade maximum stored power …

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Spectral Singularities With Directional Sensitivity, Hamidreza Ramezani Apr 2021

Spectral Singularities With Directional Sensitivity, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

We propose a class of spectral singularities that are sensitive to the direction of excitation and arise in nonlinear systems with broken parity symmetry. These spectral singularities are sensitive to the direction of the incident beam and result in diverging transmission and reflection for the left (right) incident, while the transmission and reflection of the right (left) side of the system remain finite. For the pedagogical reason, first we review the scattering formalism in nonlinear systems using an abstract δ-function model. Then, using a parity symmetry broken nonlinear system consisting of two δ functions, one linear and the other nonlinear, …

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Pinta: The Ugmrt Data Processing Pipeline For The Indian Pulsar Timing Array, Abhimanyu Susobhanan, Yogesh Maan, Bhal Chandra Joshi, T. Prabu, Shantanu Desai, K. Nobleson, Sai Chaitanya Susarla, Raghav Girgaonkar, Lankeswar Dey, Suryarao Bethapudi Apr 2021

Pinta: The Ugmrt Data Processing Pipeline For The Indian Pulsar Timing Array, Abhimanyu Susobhanan, Yogesh Maan, Bhal Chandra Joshi, T. Prabu, Shantanu Desai, K. Nobleson, Sai Chaitanya Susarla, Raghav Girgaonkar, Lankeswar Dey, Suryarao Bethapudi

Physics & Astronomy Faculty Publications

We introduce pinta, a pipeline for reducing the upgraded Giant Metre-wave Radio Telescope (uGMRT) raw pulsar timing data, developed for the Indian Pulsar Timing Array experiment. We provide a detailed description of the workflow and usage of pinta, as well as its computational performance and RFI mitigation characteristics. We also discuss a novel and independent determination of the relative time offsets between the different back-end modes of uGMRT and the interpretation of the uGMRT observation frequency settings and their agreement with results obtained from engineering tests. Further, we demonstrate the capability of pinta to generate data products which can produce …

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Pint: A Modern Software Package For Pulsar Timing, Jing Luo, S. M. Ransom, Paul B. Demorest, P. S. Ray, Anne M. Archibald, M. Kerr, Ross J. Jennings, Matteo Bachetti, Rutger Van Haasteren, Fredrick A. Jenet Apr 2021

Pint: A Modern Software Package For Pulsar Timing, Jing Luo, S. M. Ransom, Paul B. Demorest, P. S. Ray, Anne M. Archibald, M. Kerr, Ross J. Jennings, Matteo Bachetti, Rutger Van Haasteren, Fredrick A. Jenet

Physics & Astronomy Faculty Publications

Over the past few decades, the measurement precision of some pulsar timing experiments has advanced from ~10 μs to ~10 ns, revealing many subtle phenomena. Such high precision demands both careful data handling and sophisticated timing models to avoid systematic error. To achieve these goals, we present PINT (PINT Is Not Tempo3), a high-precision Python pulsar timing data analysis package, which is hosted on GitHub and available on the Python Package Index (PyPI) as pint-pulsar. PINT is well tested, validated, object oriented, and modular, enabling interactive data analysis and providing an extensible and flexible development platform for timing applications. …

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Common-Spectrum Process Versus Cross-Correlation For Gravitational-Wave Searches Using Pulsar Timing Arrays, Joseph D. Romano, ‪Jeffrey S. Hazboun, X. Siemens, Anne M. Archibald Mar 2021

Common-Spectrum Process Versus Cross-Correlation For Gravitational-Wave Searches Using Pulsar Timing Arrays, Joseph D. Romano, ‪Jeffrey S. Hazboun, X. Siemens, Anne M. Archibald

Physics & Astronomy Faculty Publications

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has recently reported strong statistical evidence for a common-spectrum red-noise process for all pulsars, as seen in their 12.5-yr analysis for an isotropic stochastic gravitational-wave signal. However, there is currently very little evidence for quadrupolar spatial correlations across the pulsars in the array, which is needed to make a confident claim of detection of a stochastic gravitational-wave background. In this paper, we provide a “back-of-the-envelope” illustration of the NANOGrav 12.5-yr results for the nonexpert reader, using a very simple signal+noise model and frequentist statistics. We show that the current lack of …

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Frequentist Versus Bayesian Analyses: Cross-Correlation As An Approximate Sufficient Statistic For Ligo-Virgo Stochastic Background Searches, Andrew Matas, Joseph D. Romano Mar 2021

Frequentist Versus Bayesian Analyses: Cross-Correlation As An Approximate Sufficient Statistic For Ligo-Virgo Stochastic Background Searches, Andrew Matas, Joseph D. Romano

Physics & Astronomy Faculty Publications

Sufficient statistics are combinations of data in terms of which the likelihood function can be rewritten without loss of information. Depending on the data volume reduction, the use of sufficient statistics as a preliminary step in a Bayesian analysis can lead to significant increases in efficiency when sampling from posterior distributions of model parameters. Here we show that the frequency integrand of the cross-correlation statistic and its variance are approximate sufficient statistics for ground-based searches for stochastic gravitational-wave backgrounds. The sufficient statistics are approximate because one works in the weak-signal approximation and uses measured estimates of the autocorrelated power in …

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All-Sky Search In Early O3 Ligo Data For Continuous Gravitational-Wave Signals From Unknown Neutron Stars In Binary Systems, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, K. E. Ramirez, W. H. Wang Mar 2021

All-Sky Search In Early O3 Ligo Data For Continuous Gravitational-Wave Signals From Unknown Neutron Stars In Binary Systems, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, K. E. Ramirez, W. H. Wang

Physics & Astronomy Faculty Publications

Rapidly spinning neutron stars are promising sources of continuous gravitational waves. Detecting such a signal would allow probing of the physical properties of matter under extreme conditions. A significant fraction of the known pulsar population belongs to binary systems. Searching for unknown neutron stars in binary systems requires specialized algorithms to address unknown orbital frequency modulations. We present a search for continuous gravitational waves emitted by neutron stars in binary systems in early data from the third observing run of the Advanced LIGO and Advanced Virgo detectors using the semicoherent, GPU-accelerated, BinarySkyHough pipeline. The search analyzes the most sensitive frequency …

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A Gravitational-Wave Measurement Of The Hubble Constant Following The Second Observing Run Of Advanced Ligo And Virgo, B. P. Abbott, R. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, Satzhan Sitmukhambetov, Robert Stone, D. Tuyenbayev, Wenhui Wang, Adam Zadrozny Mar 2021

A Gravitational-Wave Measurement Of The Hubble Constant Following The Second Observing Run Of Advanced Ligo And Virgo, B. P. Abbott, R. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, Satzhan Sitmukhambetov, Robert Stone, D. Tuyenbayev, Wenhui Wang, Adam Zadrozny

Physics & Astronomy Faculty Publications

This paper presents the gravitational-wave measurement of the Hubble constant (H0) using the detections from the first and second observing runs of the Advanced LIGO and Virgo detector network. The presence of the transient electromagnetic counterpart of the binary neutron star GW170817 led to the first standard-siren measurement of H0. Here we additionally use binary black hole detections in conjunction with galaxy catalogs and report a joint measurement. Our updated measurement is H0 = - 69+8 16 km s−1 Mpc−1 (68.3% of the highest density posterior interval with a flat-in-log prior) which is an improvement by a factor of 1.04 …

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Non-Diffracting States At Exceptional Points, Cem Yuce, Hamidreza Ramezani Feb 2021

Non-Diffracting States At Exceptional Points, Cem Yuce, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

We propose to use exceptional points (EPs) to construct diffraction-free beam propagation and localized power oscillation in lattices. We specifically consider two systems to utilize EPs for diffraction-free beam propagation, one in synthetic gauge lattices and the other one, in unidirectionally coupled resonators where each resonator individually is capable of creating orbital angular momentum beams (OAM). In the second system, we introduce the concept of robust and tunable OAM beam propagation in discrete lattices. We show that one can create robust OAM beams in an arbitrary number of sites of a photonic lattice. Furthermore, we report power oscillation at the …

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Extending The Frequency Reach Of Pulsar Timing Array Based Gravitational Wave Search Without High Cadence Observations, Yan Wang, Soumya Mohanty, Zhoujian Cao Feb 2021

Extending The Frequency Reach Of Pulsar Timing Array Based Gravitational Wave Search Without High Cadence Observations, Yan Wang, Soumya Mohanty, Zhoujian Cao

Physics & Astronomy Faculty Publications

Gravitational wave (GW) searches using pulsar timing arrays (PTAs) are assumed to be limited by the typical average observational cadence of 1/(2 weeks) for a single pulsar to GW frequencies . 4 × 10−7 Hz. We show that this assumption is incorrect and that a PTA can detect signals with much higher frequencies, which are preserved in the data due to aliasing, by exploiting asynchronous observations from multiple pulsars. This allows an observation strategy that is scalable to future large-scale PTAs containing O(103) pulsars, enabled by the Five-hundred meter Aperture Spherical Telescope and the Square Kilometer Array, without requiring a …

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Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites, Farnaz Safi Samghabadi, Long Chang, Mohammad Khodadadi, Karen S. Martirosyan, Dmitri Litvinov Feb 2021

Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites, Farnaz Safi Samghabadi, Long Chang, Mohammad Khodadadi, Karen S. Martirosyan, Dmitri Litvinov

Physics & Astronomy Faculty Publications

Cobalt ferrite (CoFe2O4)/barium titanate (BaTiO3) particulate composites exhibiting high magnetoelectric coefficients were synthesized from low-cost commercial precursors using mechanical ball milling followed by high-temperature annealing. CoFe2O4 (20 nm–50 nm) and either cubic or tetragonal BaTiO3 nanoparticle powders were used for the synthesis. It was found that utilizing a 50nm cubic BaTiO3 powder as a precursor results in a composite with a magnetoelectric coupling coefficient value as high as 4.3 mV/Oe cm, which is comparable to those of chemically synthesized core–shell CoFe2O4–BaTiO3 nanoparticles. The microstructure of these composites is dramatically different from the composite synthesized using 200nm tetragonal BaTiO3 powder. CoFe2O4 …

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Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites, Farnaz Safi Samghabadi, Long Chang, Mohammad Khodadadi, Karen S. Martirosyan, Dmitri Litvinov Feb 2021

Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites, Farnaz Safi Samghabadi, Long Chang, Mohammad Khodadadi, Karen S. Martirosyan, Dmitri Litvinov

Physics & Astronomy Faculty Publications

Cobalt ferrite (CoFe2O4)/barium titanate (BaTiO3) particulate composites exhibiting high magnetoelectric coefficients were synthesized from low-cost commercial precursors using mechanical ball milling followed by high-temperature annealing. CoFe2O4 (20 nm–50 nm) and either cubic or tetragonal BaTiO3 nanoparticle powders were used for the synthesis. It was found that utilizing a 50nm cubic BaTiO3 powder as a precursor results in a composite with a magnetoelectric coupling coefficient value as high as 4.3 mV/Oe cm, which is comparable to those of chemically synthesized core–shell CoFe2O4–BaTiO3 nanoparticles. The microstructure of these composites is dramatically different from the composite synthesized using 200nm tetragonal BaTiO3 powder. CoFe2O4 …

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Carbon Combustion Synthesis Of Janus-Like Particles Of Magnetoelectric Cobalt Ferrite And Barium Titanate, Carlos Trevino De Leo, Gamage Chamath Dannangoda, Mkhitar A. Hobosyan, J. T. Held, F. Safi Samghabadi, Mohammad Khodadadi, Dmitri Litvinov, K. A. Mkhoyan, Karen S. Martirosyan Feb 2021

Carbon Combustion Synthesis Of Janus-Like Particles Of Magnetoelectric Cobalt Ferrite And Barium Titanate, Carlos Trevino De Leo, Gamage Chamath Dannangoda, Mkhitar A. Hobosyan, J. T. Held, F. Safi Samghabadi, Mohammad Khodadadi, Dmitri Litvinov, K. A. Mkhoyan, Karen S. Martirosyan

Physics & Astronomy Faculty Publications

Carbon combustion synthesis of oxides was applied for quick and energy efficient production of multiferroic composite of cobalt ferrite and barium titanate to form Janus-like particles matrix structure. The exothermic oxidation of carbon nanoparticles with an average size of 5 nm and a specific surface area of 110 m2/g generates a self-propagating thermal wave with peak temperature of up to 1000 °C. The thermal front rapidly propagates through the mixture of solid reactants (magnetic- CoFe2O4 and ferroelectric-BaTiO3) and results in localized hot-spot sintering of magneto-electric phases to form a nanocomposite structure. Carbon is not incorporated in the product and is …

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Open Data From The First And Second Observing Runs Of Advanced Ligo And Advanced Virgo, Rich Abbott, Thomas D. Abbott, Amit Aich, Guldauren Bissenbayeva, Teviet Creighton, Mario C. Diaz, Malik Rakhmanov, Karla E. Ramirez, Palash K. Roy, Wenhui Wang, Adam Zadrozny Jan 2021

Open Data From The First And Second Observing Runs Of Advanced Ligo And Advanced Virgo, Rich Abbott, Thomas D. Abbott, Amit Aich, Guldauren Bissenbayeva, Teviet Creighton, Mario C. Diaz, Malik Rakhmanov, Karla E. Ramirez, Palash K. Roy, Wenhui Wang, Adam Zadrozny

Physics & Astronomy Faculty Publications

Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http://gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software.

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Open Data From The First And Second Observing Runs Of Advanced Ligo And Advanced Virgo, R. Abbott, T. D. Abbott, S. Abraham, Fausto Acernese, Teviet Creighton, Mario C. Diaz, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, Palash K. Roy, Wenhui Wang, Adam Zadrozny Jan 2021

Open Data From The First And Second Observing Runs Of Advanced Ligo And Advanced Virgo, R. Abbott, T. D. Abbott, S. Abraham, Fausto Acernese, Teviet Creighton, Mario C. Diaz, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, Palash K. Roy, Wenhui Wang, Adam Zadrozny

Physics & Astronomy Faculty Publications

Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http://gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software.

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The Nanograv 12.5 Yr Data Set: Wideband Timing Of 47 Millisecond Pulsars, Md F. Alam, Zaven Arzoumanian, Paul T. Baker, Harsha Blumer, Keith E. Bohler, Keeisi Caballero, Richard S. Camuccio, Yhamil Garcia, Jing Luo Jan 2021

The Nanograv 12.5 Yr Data Set: Wideband Timing Of 47 Millisecond Pulsars, Md F. Alam, Zaven Arzoumanian, Paul T. Baker, Harsha Blumer, Keith E. Bohler, Keeisi Caballero, Richard S. Camuccio, Yhamil Garcia, Jing Luo

Physics & Astronomy Faculty Publications

We present a new analysis of the profile data from the 47 millisecond pulsars comprising the 12.5 yr data set of the North American Nanohertz Observatory for Gravitational Waves, which is presented in a parallel paper (Alam et al., hereafter NG12.5). Our reprocessing is performed using “wideband” timing methods, which use frequency-dependent template profiles, simultaneous time-of-arrival (TOA) and dispersion measure (DM) measurements from broadband observations, and novel analysis techniques. In particular, the wideband DM measurements are used to constrain the DM portion of the timing model. We compare the ensemble timing results to those in NG12.5 by examining the …

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Agn Jets And A Fanciful Trio Of Black Holes In The Abell 85 Brightest Cluster Galaxy, Juan P. Madrid Jan 2021

Agn Jets And A Fanciful Trio Of Black Holes In The Abell 85 Brightest Cluster Galaxy, Juan P. Madrid

Physics & Astronomy Faculty Publications

A new radio map of the Abell 85 Brightest Cluster Galaxy (BCG) was obtained with the Karl G. Jansky Very Large Array. With a resolution of 002, this radio image shows two kiloparsec-scale bipolar active galactic nucleus jets emanating from the active galactic nucleus of the A85 BCG. The galaxy core appears as a single entity on the new radio map. It has been assumed that the A85 BCG contained a binary black hole in its core. However, Chandra X-ray data and the new high-resolution radio map show no evidence that the A85 BCG harbors a binary black hole. The …

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Ligo Detector Characterization In The Second And Third Observing Runs, D. Davis, J. S. Areeda, B. K. Berger, R. Bruntz, A. Effler, R. C. Essick, R. P. Fisher, B. Martinez, Karla E. Ramirez, P. Godwin Jan 2021

Ligo Detector Characterization In The Second And Third Observing Runs, D. Davis, J. S. Areeda, B. K. Berger, R. Bruntz, A. Effler, R. C. Essick, R. P. Fisher, B. Martinez, Karla E. Ramirez, P. Godwin

Physics & Astronomy Faculty Publications

The characterization of the Advanced LIGO detectors in the second and third observing runs has increased the sensitivity of the instruments, allowing for a higher number of detectable gravitational-wave signals, and provided confirmation of all observed gravitational-wave events. In this work, we present the methods used to characterize the LIGO detectors and curate the publicly available datasets, including the LIGO strain data and data quality products. We describe the essential role of these datasets in LIGO–Virgo Collaboration analyses of gravitational-waves from both transient and persistent sources and include details on the provenance of these datasets in order to support analyses …

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Search For Continuous Gravitational-Wave Signals In Pulsar Timing Residuals: A New Scalable Approach With Diffusive Nested Sampling, Yu-Yang Songsheng, Yi-Qian Qian, Yan-Rong Li, Pu Du, Jie-Wen Chen, Yan Wang, Soumya Mohanty, Jian-Min Wang Jan 2021

Search For Continuous Gravitational-Wave Signals In Pulsar Timing Residuals: A New Scalable Approach With Diffusive Nested Sampling, Yu-Yang Songsheng, Yi-Qian Qian, Yan-Rong Li, Pu Du, Jie-Wen Chen, Yan Wang, Soumya Mohanty, Jian-Min Wang

Physics & Astronomy Faculty Publications

Detecting continuous nanohertz gravitational waves (GWs) generated by individual close binaries of supermassive black holes (CB-SMBHs) is one of the primary objectives of pulsar timing arrays (PTAs). The detection sensitivity is slated to increase significantly as the number of well-timed millisecond pulsars will increase by more than an order of magnitude with the advent of next-generation radio telescopes. Currently, the Bayesian analysis pipeline using parallel tempering Markov Chain Monte Carlo has been applied in multiple studies for CB-SMBH searches, but it may be challenged by the high dimensionality of the parameter space for future large-scale PTAs. One solution is to …

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