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Articles 811 - 840 of 2944

Full-Text Articles in Astrophysics and Astronomy

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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Identifying, Analyzing, And Using Discriminatory Variables For Classification Of Neutrino Signal And Background Noise In Multivariate Analysis In The Askaryan Radio Array Experiment, Jesse Osborn Mar 2021

Identifying, Analyzing, And Using Discriminatory Variables For Classification Of Neutrino Signal And Background Noise In Multivariate Analysis In The Askaryan Radio Array Experiment, Jesse Osborn

Honors Program: Senior Projects (Public)

The Askaryan Radio Array Experiment, located near the South Pole, works to pinpoint specific instances of neutrinos from outside the solar system interacting with nucleons inside the Antarctic ice, emitting radio waves. I have taken data from the ARA stations which is presumed to be background noise and compared it to simulated data meant to look like a neutrino signal. I developed a suite of variables for discrimination between the two data sets, using a computer algorithm to generate a single output variable which can be used to distinguish noise events from signal events. I maximized this discrimination process for …

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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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Updated Miniboone Neutrino Oscillation Results With Increased Data And New Background Studies, A. A. Aguilar-Arevalo, B. C. Brown, J. M. Conrad, R. Dharmapalan, A. Diaz, Z. Djurcic, D. A. Finley, R. Ford, G. T. Garvey, S. Gollapinni, A. Hourlier, E-C Huang, N. W. Kamp, G. Karagiorgi, T. Katori, T. Kobilarcik, K. Lin, W. C. Louis, C. Mariani, W. Marsh, G. B. Mills, J. Mirabal-Martinez, C. D. Moore, R. H. Nelson, J. Nowak, I Parmaksiz, Z. Pavlovic, H. Ray, B. P. Roe, A. D. Russell, A. Schneider, M. H. Shaevitz, H. Siegel, J. Spitz, I. Stancu, R. Tayloe, R. T. Thornton, M. Tzanov, R. G. Van De Water, D. H. White, E. D. Zimmerman Mar 2021

Updated Miniboone Neutrino Oscillation Results With Increased Data And New Background Studies, A. A. Aguilar-Arevalo, B. C. Brown, J. M. Conrad, R. Dharmapalan, A. Diaz, Z. Djurcic, D. A. Finley, R. Ford, G. T. Garvey, S. Gollapinni, A. Hourlier, E-C Huang, N. W. Kamp, G. Karagiorgi, T. Katori, T. Kobilarcik, K. Lin, W. C. Louis, C. Mariani, W. Marsh, G. B. Mills, J. Mirabal-Martinez, C. D. Moore, R. H. Nelson, J. Nowak, I Parmaksiz, Z. Pavlovic, H. Ray, B. P. Roe, A. D. Russell, A. Schneider, M. H. Shaevitz, H. Siegel, J. Spitz, I. Stancu, R. Tayloe, R. T. Thornton, M. Tzanov, R. G. Van De Water, D. H. White, E. D. Zimmerman

Faculty Publications

The MiniBooNE experiment at Fermilab reports a total excess of 638.0 +/- 52.1(stat) +/- 122.2(syst) electronlike events from a data sample corresponding to 18.75 x 10(20) protons-on-target in neutrino mode, which is a 46% increase in the data sample with respect to previously published results and 11.27 x 10(20) protons-on-target in antineutrino mode. The overall significance of the excess, 4.8 sigma, is limited by systematic uncertainties, assumed to be Gaussian, as the statistical significance of the excess is 12.2 sigma. The additional statistics allow several studies to address questions on the source of the excess. First, we provide two-dimensional plots …

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Gibbs Point Process Model For Young Star Clusters In M33, Dayi Li, Pauline Barmby Mar 2021

Gibbs Point Process Model For Young Star Clusters In M33, Dayi Li, Pauline Barmby

Physics and Astronomy Publications

We demonstrate the power of Gibbs point process models from the spatial statistics literature when applied to studies of resolved galaxies. We conduct a rigorous analysis of the spatial distributions of objects in the star formation complexes of M33, including giant molecular clouds (GMCs) and young stellar cluster candidates (YSCCs). We choose a hierarchical model structure from GMCs to YSCCs based on the natural formation hierarchy between them. This approach circumvents the limitations of the empirical two-point correlation function analysis by naturally accounting for the inhomogeneity present in the distribution of YSCCs. We also investigate the effects of GMCs' properties …

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Quasinormal Modes And Their Overtones At The Common Horizon In A Binary Black Hole Merger, Pierre Mourier, Xisco Jimenez Forteza, Daniel Pook-Kolb, Dadri Krishnan, Erik Schnetter Feb 2021

Quasinormal Modes And Their Overtones At The Common Horizon In A Binary Black Hole Merger, Pierre Mourier, Xisco Jimenez Forteza, Daniel Pook-Kolb, Dadri Krishnan, Erik Schnetter

Faculty Publications

It is expected that all astrophysical black holes in equilibrium are well described by the Kerr solution. Moreover, any black hole far away from equilibrium, such as one initially formed in a compact binary merger or by the collapse of a massive star, will eventually reach a final equilibrium Kerr state. At sufficiently late times in this process of reaching equilibrium, we expect that the black hole is modeled as a perturbation around the final state. The emitted gravitational waves will then be damped sinusoids with frequencies and damping times given by the quasinormal mode spectrum of the final Kerr …

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Differential Cross Sections For Λ(1520) Using Photoproduction At Clas, U. Shrestha, T. Chetry, C. Djalali, K. Hicks, S. I. Nam, K. P. Adhikari, M. Amaryan, G. Angelini, H. Atac, L. Barion, M. Battaglieri, I. Bedlinskiy, F. Benmokhtar, A. Bianconi, A. S. Biselli, M. Bondi, F. Bossú, S. Boiarinov, W. J. Briscoe, W. K. Brooks, Steffen Strauch, Et. Al. Feb 2021

Differential Cross Sections For Λ(1520) Using Photoproduction At Clas, U. Shrestha, T. Chetry, C. Djalali, K. Hicks, S. I. Nam, K. P. Adhikari, M. Amaryan, G. Angelini, H. Atac, L. Barion, M. Battaglieri, I. Bedlinskiy, F. Benmokhtar, A. Bianconi, A. S. Biselli, M. Bondi, F. Bossú, S. Boiarinov, W. J. Briscoe, W. K. Brooks, Steffen Strauch, Et. Al.

Faculty Publications

The reaction 𝛾⁢𝑝→𝐾+⁢Λ⁡(1520) using photoproduction data from the CLAS 𝑔⁡12 experiment at Jefferson Lab is studied. The decay of Λ⁡(1520) into two exclusive channels, Σ+⁢𝜋− and Σ−⁢𝜋+, is studied from the detected 𝐾+, 𝜋+, and 𝜋− particles. A good agreement is established for the Λ⁡(1520) differential cross sections with the previous CLAS measurements. The differential cross sections as a function of center-of-mass angle are extended to higher photon energies. Newly added are the differential cross sections as a function of invariant four-momentum transfer 𝑡, which is the natural variable to use for a theoretical model based on a Regge-exchange reaction …

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The Pedagogical Representation Of Mass Functions With Lego And Their Origin, Stefan Kautsch Feb 2021

The Pedagogical Representation Of Mass Functions With Lego And Their Origin, Stefan Kautsch

Chemistry and Physics Faculty Articles

We promote the teaching of mass functions as an integral part of an interdisciplinary science education. Mass functions characterize the frequency distributions of objects with different masses on all cosmic scales. We intend to enhance experiential learning of this concept with a creative LEGO brick experiment for a diverse student audience. To our surprise, the LEGO mass function is not only qualitatively but also quantitatively comparable to mass functions found across the universe. We also discuss the relation between gravitation and mass distributions as a possible explanation for the continuity of the universal mass function.

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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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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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Beam Spin Asymmetry In Semi-Inclusive Electroproduction Of Hadron Pairs, M. Mirazita, H. Avakian, A. Courtoy, S. Pisano, S. Pisano, S. Adhikari, M. J. Amaryan, Giovanni Angelini, H. Atac, N. A. Baltzell, L. Barion, M. Battaglieri, I. Bedlinskiy, Fatiha Benmokhtar, A. Bianconi, A. S. Biselli, F. Bossù, S. Boiarinov, W. J. Briscoe, W. K. Brooks, Steffen Strauch, Et. Al. Jan 2021

Beam Spin Asymmetry In Semi-Inclusive Electroproduction Of Hadron Pairs, M. Mirazita, H. Avakian, A. Courtoy, S. Pisano, S. Pisano, S. Adhikari, M. J. Amaryan, Giovanni Angelini, H. Atac, N. A. Baltzell, L. Barion, M. Battaglieri, I. Bedlinskiy, Fatiha Benmokhtar, A. Bianconi, A. S. Biselli, F. Bossù, S. Boiarinov, W. J. Briscoe, W. K. Brooks, Steffen Strauch, Et. Al.

Faculty Publications

A first measurement of the longitudinal beam spin asymmetry 𝐴𝐿⁢𝑈 in the semi-inclusive electroproduction of pairs of charged pions is reported. 𝐴𝐿⁢𝑈 is a higher-twist observable and offers the cleanest access to the nucleon twist-3 parton distribution function 𝑒⁡(𝑥). Data have been collected in the Hall-B at Jefferson Lab by impinging a 5.498-GeV electron beam on a liquid-hydrogen target, and reconstructing the scattered electron and the pion pair with the CLAS detector. One-dimensional projections of the 𝐴sin⁡𝜙𝑅 LU moments are extracted for the kinematic variables of interest in the valence quark region. The understanding of dihadron production …

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Search For Slow Magnetic Monopoles With The Nova Detector On The Surface, M. A. Acero, P. Adamson, L. Aliaga, T. Alion, V. Allakhverdian, N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, L. Asquith, A. Aurisano, A. Back, C. Backhouse, M. Biard, N. Balashov, P. Baldi, B. A. Bambah, S. Bashar, K. Bays, S. Bending, R. Bernstein, Roberto Petti, Sanjib R. Mishra Ph.D., Et. Al. Jan 2021

Search For Slow Magnetic Monopoles With The Nova Detector On The Surface, M. A. Acero, P. Adamson, L. Aliaga, T. Alion, V. Allakhverdian, N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, L. Asquith, A. Aurisano, A. Back, C. Backhouse, M. Biard, N. Balashov, P. Baldi, B. A. Bambah, S. Bashar, K. Bays, S. Bending, R. Bernstein, Roberto Petti, Sanjib R. Mishra Ph.D., Et. Al.

Faculty Publications

We report a search for a magnetic monopole component of the cosmic-ray flux in a 95-day exposure of the NOvA experiment’s Far Detector, a 14 kt segmented liquid scintillator detector designed primarily to observe GeV-scale electron neutrinos. No events consistent with monopoles were observed, setting an upper limit on the flux of 2 × 10−14 cm−2 s−1 sr−1 at 90% C.L. for monopole speed 6 × 10−4 < β < 5 × 10−3 and mass greater than 5 × 108 GeV. Because of NOvA’s small overburden of 3 meters-water equivalent, this constraint covers a previously unexplored low-mass region.

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Fourier Transform Of The Continuous Gravitational Wave Signal, Sree Ram Valluri, V. Dergachev, X. Zhang, Farrukh Chishtie Jan 2021

Fourier Transform Of The Continuous Gravitational Wave Signal, Sree Ram Valluri, V. Dergachev, X. Zhang, Farrukh Chishtie

Physics and Astronomy Publications

The direct detection of continuous gravitational waves from pulsars is a much anticipated discovery in the emerging field of multimessenger gravitational wave (GW) astronomy. Because putative pulsar signals are exceedingly weak large amounts of data need to be integrated to achieve desired sensitivity. Contemporary searches use ingenious ad hoc methods to reduce computational complexity. In this paper we provide analytical expressions for the Fourier transform of realistic pulsar signals. This provides description of the manifold of pulsar signals in the Fourier domain, used by many search methods. We analyze the shape of the Fourier transform and provide explicit formulas for …

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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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Proton Aurora At Mars: Assessing The Characteristics, Variability, And Driving Mechanisms Of A Newly Discovered Phenomenon, Andréa C.G. Hughes Jan 2021

Proton Aurora At Mars: Assessing The Characteristics, Variability, And Driving Mechanisms Of A Newly Discovered Phenomenon, Andréa C.G. Hughes

Doctoral Dissertations and Master's Theses

The purpose of this doctoral research dissertation is to develop a deeper understanding of the phenomenology, variability and driving processes of proton aurora at Mars. Proton aurora are the most recently discovered of the three types of Martian aurora. Due to Mars’ lack of a global dipole magnetic field, the formation processes of Martian proton aurora are uniquely different than aurora on Earth. Martian proton aurora are expected to form on the planet’s dayside via electron stripping/charge exchange processes between solar wind protons and the neutral hydrogen corona. Herein, I present the results of a study of proton aurora at …

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Exclusion Statistics For Particles With A Discrete Spectrum, Stéphane Ouvry, Alexios P. Polychronakos Jan 2021

Exclusion Statistics For Particles With A Discrete Spectrum, Stéphane Ouvry, Alexios P. Polychronakos

Publications and Research

We formulate and study the microscopic statistical mechanics of systems of particles with exclusion statistics in a discrete one-body spectrum. The statistical mechanics of these systems can be expressed in terms of effective single-level grand partition functions obeying a generalization of the standard thermodynamic exclusion statistics equation of state. We derive explicit expressions for the thermodynamic potential in terms of microscopic cluster coefficients and show that the mean occupation numbers of levels satisfy a nesting relation involving a number of adjacent levels determined by the exclusion parameter. We apply the formalism to the harmonic Calogero model and point out a …

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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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A Detailed X-Ray Analysis Of The Cold Front In Relics Cluster A2163, Anne Poy Jan 2021

A Detailed X-Ray Analysis Of The Cold Front In Relics Cluster A2163, Anne Poy

CMC Senior Theses

Galaxy clusters are the largest gravitationally bound objects in the Universe. Studying them can teach us about how they merge and grow, which in turn provides unparalleled information about the history of the evolution of the Universe. X-ray observations of galaxy clusters have uncovered substructure in the hot, X-ray emitting gas known as the intracluster mediums (ICM). Substructure indicates that the ICM has been churned up, possibly by a significant off-axis merger event. This substructure includes cold fronts, sloshing spirals, and shocks. We present deep Chandra observations of the merging cluster Abell 2163. We investigate the global spectrum and find …

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Magnetic Properties Of Lsmo/Sto Thin Films: Magnetocaloric, Spin Dynamics And Magnetic Viscosity Investigations, Navid Mottaghi Jan 2021

Magnetic Properties Of Lsmo/Sto Thin Films: Magnetocaloric, Spin Dynamics And Magnetic Viscosity Investigations, Navid Mottaghi

Graduate Theses, Dissertations, and Problem Reports (ETD)

While other films are discussed, this dissertation will focus on detailed studies of the dc and ac bulk magnetometry in a characteristic 7.6 nm thin film of La0.7Sr0.3MnO3 grown on SrTiO3 (001). The dc bulk magnetometry measurements show that the sample is magnetically inhomogeneous. Temperature variation of magnetization (M vs. T) was measured in zero-field-cooled and field-cooled protocols to determine the blocking temperature TB in different applied magnetic fields. The field variation of TB is interpreted as the presence of embedded spin clusters of 1.4 nm. Moreover, the M vs. …

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Enhancing Student Learning In Introductory Physics Through Funds Of Knowledge, Liang Zeng, Guang Zeng Jan 2021

Enhancing Student Learning In Introductory Physics Through Funds Of Knowledge, Liang Zeng, Guang Zeng

Physics & Astronomy Faculty Publications

Researchers have reported the funds of knowledge (FK) pedagogical approach effective in engaging minority students in learning. However, there are a lack of studies connecting FK to introductory college physics or physical science classes. By using examples from regional Mexican-American lived experiences at an Hispanic-serving institution located along the recently politicized U.S.-Mexico border, this paper provides evidence to show how physics educators can use FK to engage students in learning introductory college physics concepts.

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Reducing Scattered Light In Ligo's Third Observing Run, S. Soni, C. Austin, A. Effler, R. M. S. Schofield, G. Gonzalez, V. V. Frolov, J. C. Driggers, A. Pele, A. L. Urban, G. Valdes, K. E. Ramirez Jan 2021

Reducing Scattered Light In Ligo's Third Observing Run, S. Soni, C. Austin, A. Effler, R. M. S. Schofield, G. Gonzalez, V. V. Frolov, J. C. Driggers, A. Pele, A. L. Urban, G. Valdes, K. E. Ramirez

Physics & Astronomy Faculty Publications

Noise due to scattered light has been a frequent disturbance in the advanced LIGO gravitational wave detectors, hindering the detection of gravitational waves. The non stationary scatter noise caused by low frequency motion can be recognized as arches in the time-frequency plane of the gravitational wave channel. In this paper, we characterize the scattering noise for LIGO and Virgo's third observing run O3 from April, 2019 to March, 2020. We find at least two different populations of scattering noise and we investigate the multiple origins of one of them as well as its mitigation. We find that relative motion between …

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Grappling With Covid-19 By Imposing And Lifting Nonpharmaceutical Interventions In Sri Lanka: A Modeling Perspective, Mahesh Jayaweera, Chamath Dannongoda, Dilum Dilshan, Janith Dissanayake, Hasini Perera, Jagath Manatunge, Buddhika Gunawardana Jan 2021

Grappling With Covid-19 By Imposing And Lifting Nonpharmaceutical Interventions In Sri Lanka: A Modeling Perspective, Mahesh Jayaweera, Chamath Dannongoda, Dilum Dilshan, Janith Dissanayake, Hasini Perera, Jagath Manatunge, Buddhika Gunawardana

Physics & Astronomy Faculty Publications

The imposition and lifting of non-pharmaceutical interventions (NPIs) to avert the COVID19 pandemic have gained popularity worldwide and will continue to be enforced until herd immunity is achieved. We developed a linear regression model to ascertain the nexus between the time-varying reproduction number averaged over a time window of six days (Rts) and seven NPIs: contact tracing, quarantine efforts, social distancing and health checks, hand hygiene, wearing of facemasks, lockdown and isolation, and health-related supports. Our analysis suggests that the second wave that emerged in Sri Lanka in early October 2020 continued despite numerous NPIs. The model indicates that the …

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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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Small-Scale Dynamics Of Photospheric Magnetic Activities And Their Chromospheric Responses, Jiasheng Wang Dec 2020

Small-Scale Dynamics Of Photospheric Magnetic Activities And Their Chromospheric Responses, Jiasheng Wang

Dissertations

The evolution of photospheric magnetic fields is considered as the fundamental source of forming atmospheric structures and triggering most solar activities, including flares and mass ejections on various scales (CMEs, jets, etc.). With the implementation of high-resolution observational instruments, small-scale details of magnetic features are recognized that can provide important information regarding the evolution in active regions and the connection between photospheric magnetic reconnection and jet-like ejections in the quiet Sun. This research takes advantage of the exceptionally high-resolution measurements of vector magnetic field and imaging observations by the Goode Solar Telescope, and UV/EUV imaging observations from space-based instruments. The …

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