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University of Texas Rio Grande Valley

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Articles 181 - 210 of 832

Full-Text Articles in Astrophysics and Astronomy

Isolated And Dynamical Black Hole Mergers With B-Pop: The Role Of Star Formation And Dynamics, Star Cluster Evolution, Natal Kicks, Mass And Spins, And Hierarchical Mergers, Manuel Arca Sedda, Michaela Mapelli, Matthew Benacquista, Mario Spera Apr 2023

Isolated And Dynamical Black Hole Mergers With B-Pop: The Role Of Star Formation And Dynamics, Star Cluster Evolution, Natal Kicks, Mass And Spins, And Hierarchical Mergers, Manuel Arca Sedda, Michaela Mapelli, Matthew Benacquista, Mario Spera

Physics & Astronomy Faculty Publications

The current interpretation of LIGO–Virgo–KAGRA data suggests that the primary mass function of merging binary black holes (BBHs) at redshift z ≲ 1 contains multiple structures, while spins are relatively low. Theoretical models of BBH formation in different environments can provide a key to interpreting the population of observed mergers, but they require the simultaneous treatment of stellar evolution and dynamics, galaxy evolution, and general relativity. We present B-POP, a population synthesis tool to model BBH mergers formed in the field or via dynamical interactions in young, globular, and nuclear clusters. Using B-POP, we explore how black hole (BH) formation …

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Population Of Merging Compact Binaries Inferred Using Gravitational Waves Through Gwtc-3, R. Abbott, T. Abbott, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Volker Quetschke, Wen Hui Wang Mar 2023

Population Of Merging Compact Binaries Inferred Using Gravitational Waves Through Gwtc-3, R. Abbott, T. Abbott, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Volker Quetschke, Wen Hui Wang

Physics & Astronomy Faculty Publications

We report on the population properties of compact binary mergers inferred from gravitational-wave observations of these systems during the first three LIGO-Virgo observing runs. The Gravitational-Wave Transient Catalog 3 (GWTC-3) contains signals consistent with three classes of binary mergers: binary black hole, binary neutron star, and neutron star–black hole mergers. We infer the binary neutron star merger rate to be between 10 and 1700  Gpc−3 yr−1 and the neutron star–black hole merger rate to be between 7.8 and 140  Gpc−3 yr−1, assuming a constant rate density in the comoving frame and taking the union of 90% credible intervals for methods …

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Transport Effects In Non-Hermitian Nonreciprocal Systems: General Approach, Hamed Ghaemi-Dizicheh Mar 2023

Transport Effects In Non-Hermitian Nonreciprocal Systems: General Approach, Hamed Ghaemi-Dizicheh

Physics & Astronomy Faculty Publications

In this paper, we present a unifying analytical framework for identifying conditions for transport effects such as reflectionless and transparent transport, lasing, and coherent perfect absorption in non-Hermitian nonreciprocal systems using a generalized transfer matrix method. This provides a universal approach to studying the transport of tight-binding platforms, including higher-dimensional models and those with an internal degree of freedom going beyond the previously studied case of one-dimensional chains with nearest-neighbor couplings. For a specific class of tight-binding models, the relevant transport conditions and their signatures of non-Hermitian, nonreciprocal, and topological behavior are analytically tractable from a general perspective. We investigate …

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Powerful Radio Sources In The Southern Sky. I. Optical Identifications, Francesco Massaro, S. V. White, A. García-Pérez, A. Jimenez-Gallardo, A. Capetti, C. C. Cheung, W. R. Forman, C. Mazzucchelli, A. Paggi, Juan P. Madrid Mar 2023

Powerful Radio Sources In The Southern Sky. I. Optical Identifications, Francesco Massaro, S. V. White, A. García-Pérez, A. Jimenez-Gallardo, A. Capetti, C. C. Cheung, W. R. Forman, C. Mazzucchelli, A. Paggi, Juan P. Madrid

Physics & Astronomy Faculty Publications

Since the early sixties, our view of radio galaxies and quasars has been drastically shaped by discoveries made thanks to observations of radio sources listed in the Third Cambridge Catalog and its revised version (3CR). However, the largest fraction of data collected to date on 3CR sources was performed with relatively old instruments, rarely repeated and/or updated. Importantly, the 3CR contains only objects located in the Northern Hemisphere, thus having limited access to new and innovative astronomical facilities. To mitigate these limitations, we present a new catalog of powerful radio sources visible from the Southern Hemisphere, extracted from the GLEAM …

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A Candidate Magnetic Helium-Core White Dwarf In The Globular Cluster Ngc 6397, Manuel Pichardo Marcano, Liliana E. Rivera Sandoval, Thomas J. Maccarone, Rene D. Rohrmann, Craig O. Heinke, Diogo Belloni, Leandro G. Althaus, Arash Bahramian Mar 2023

A Candidate Magnetic Helium-Core White Dwarf In The Globular Cluster Ngc 6397, Manuel Pichardo Marcano, Liliana E. Rivera Sandoval, Thomas J. Maccarone, Rene D. Rohrmann, Craig O. Heinke, Diogo Belloni, Leandro G. Althaus, Arash Bahramian

Physics & Astronomy Faculty Publications

We report a peculiar variable blue star in the globular cluster (GC) NGC 6397, using Hubble Space Telescope optical imaging. Its position in the colour–magnitude diagrams and its spectrum are consistent with this star being a helium-core white dwarf (He WD) in a binary system. The optical light curve shows a periodicity at 18.5 h. We argue that this periodicity is due to the rotation of the WD and possibly due to magnetic spots on the surface of the WD. This would make this object the first candidate magnetic He WD in any GC, and the first candidate magnetic WD …

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Speed Of Sound For Hadronic And Quark Phases In A Magnetic Field, Efrain J. Ferrer, Aric Hackebill Mar 2023

Speed Of Sound For Hadronic And Quark Phases In A Magnetic Field, Efrain J. Ferrer, Aric Hackebill

Physics & Astronomy Faculty Publications

In this paper we calculate the speed of sound for three phases that may exist inside a magnetized hybrid neutron star at different density regions: A hadronic phase at low densities, quark-matter in the magnetic dual chiral density wave (MDCDW) phase at intermediate densities and a free-quark phase modeled by the MIT bag model at higher densities. It is found that the speed of sound exhibits a non-monotonic behavior, that goes from values smaller than the conformal limit ( c 2 s < 1 / 3 ) in the hadronic phase, to peak ( c 2 s > 1 / 3 ) in the MDCDW phase, to finally reach the conformal limit ( c 2 s …

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Non-Hermitian Floquet-Free Analytically Solvable Time-Dependent Systems, Hamed Ghaemi-Dizicheh, Hamidreza Ramezani Mar 2023

Non-Hermitian Floquet-Free Analytically Solvable Time-Dependent Systems, Hamed Ghaemi-Dizicheh, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

The non-Hermitian models, which are symmetric under parity (P) and time-reversal (T) operators, are the cornerstone for the fabrication of new ultra-sensitive optoelectronic devices. However, providing the gain in such systems usually demands precise control of nonlinear processes, limiting their application. In this paper, to bypass this obstacle, we introduce a class of time-dependent non-Hermitian Hamiltonians (not necessarily Floquet) that can describe a two-level system with temporally modulated on-site potential and couplings. We show that implementing an appropriate non-Unitary gauge transformation converts the original system to an effective one with a balanced gain and loss. This …

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Wallaby Pilot Survey: H I Gas Kinematics Of Galaxy Pairs In Cluster Environment, Shin-Jeong Kim, Se-Heon Oh, Jing Wang, Lister Staveley-Smith, Bärbel S. Koribalski, Minsu Kim, Hye-Jin Park, Shinna Kim, Kristine Spekkens, Juan P. Madrid Feb 2023

Wallaby Pilot Survey: H I Gas Kinematics Of Galaxy Pairs In Cluster Environment, Shin-Jeong Kim, Se-Heon Oh, Jing Wang, Lister Staveley-Smith, Bärbel S. Koribalski, Minsu Kim, Hye-Jin Park, Shinna Kim, Kristine Spekkens, Juan P. Madrid

Physics & Astronomy Faculty Publications

We examine the H I gas kinematics of galaxy pairs in two clusters and a group using Australian Square Kilometre Array Pathfinder (ASKAP) WALLABY pilot survey observations. We compare the H I properties of galaxy pair candidates in the Hydra I and Norma clusters, and the NGC 4636 group, with those of non-paired control galaxies selected in the same fields. We perform H I profile decomposition of the sample galaxies using a tool, BAYGAUD, which allows us to deblend a line-of-sight velocity profile with an optimal number of Gaussian components. We construct H I superprofiles of the sample galaxies via …

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Effects Of Silicon Dioxide As The Polar Dielectric On The Infrared Absorption Spectrum Ofthemetal-Insulator-Metal Metasurface, Ahmad K. Jafari, Matthew Gaddy, Imtiaz Ahmad, Satya R. Kachiraju, M D. Borhan Mia, Ishtiaque Ahmed, Sergey Nikishin, Myoung-Hwan Kim, Ayrton A. Bernussi Jan 2023

Effects Of Silicon Dioxide As The Polar Dielectric On The Infrared Absorption Spectrum Ofthemetal-Insulator-Metal Metasurface, Ahmad K. Jafari, Matthew Gaddy, Imtiaz Ahmad, Satya R. Kachiraju, M D. Borhan Mia, Ishtiaque Ahmed, Sergey Nikishin, Myoung-Hwan Kim, Ayrton A. Bernussi

Physics & Astronomy Faculty Publications

Metal-insulator-metal metasurfaces have been widely used as high-performance absorbers in almost all electromagnetic spectral ranges. Their absorption spectra can be engineered by making variations in the geometry of the unit cells and/or by embedding materials with specific optical constants. Including a polar dielectric in their structure is another approach for manipulating their absorption spectra. In this research, we have numerically and experimentally investigated the effect of using silicon dioxide (SiO2) as a polar dielectric on the absorption spectrum of a metal-insulator-metal metasurface composed of a tri-layer of Ni-SiO2-Ni. Our results have shown the presence of …

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The Importance Of The Pressure Anisotropy Induced By Strong Magnetic Fields On Neutron Star Physics, Efrain J. Ferrer, Aric Hackebill Jan 2023

The Importance Of The Pressure Anisotropy Induced By Strong Magnetic Fields On Neutron Star Physics, Efrain J. Ferrer, Aric Hackebill

Physics & Astronomy Faculty Publications

In this paper we discuss in some detail how the pressures determined from semi-classical statistical averaging of the energy momentum tensor in the presence of a uniform background magnetic field are anisotropic with different pressures arising along and perpendicular to the magnetic field direction. Hence, we analyze how this result can affect two important characteristics of dense magnetized systems: (i) The hadron-quark phase transition in the presence of a magnetic field, (ii) The behavior of the speed of sound in dense magnetized systems. Taking into account that large magnetic fields are expected to be present in the interior of neutron …

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Model-Based Cross-Correlation Search For Gravitational Waves From The Low-Mass X-Ray Binary Scorpius X-1 In Ligo O3 Data, R. Abbott, H. Abe, Fausto Acernese, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang Dec 2022

Model-Based Cross-Correlation Search For Gravitational Waves From The Low-Mass X-Ray Binary Scorpius X-1 In Ligo O3 Data, R. Abbott, H. Abe, Fausto Acernese, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We present the results of a model-based search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1 using LIGO detector data from the third observing run of Advanced LIGO and Advanced Virgo. This is a semicoherent search that uses details of the signal model to coherently combine data separated by less than a specified coherence time, which can be adjusted to balance sensitivity with computing cost. The search covered a range of gravitational-wave frequencies from 25 to 1600 Hz, as well as ranges in orbital speed, frequency, and phase determined from observational constraints. No significant detection candidates were …

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Powerful Yet Lonely: Is 3c 297 A High-Redshift Fossil Group?, Valentina Missaglia, Juan P. Madrid, Mischa Schirmer, Francesco Massaro, Alberto Rodríguez-Ardila, Carlos J. Donzelli, Martell Valencia, Alessandro Paggi, Ralph P. Kraft, Chiara Stuardi, Belinda J. Wilkes Dec 2022

Powerful Yet Lonely: Is 3c 297 A High-Redshift Fossil Group?, Valentina Missaglia, Juan P. Madrid, Mischa Schirmer, Francesco Massaro, Alberto Rodríguez-Ardila, Carlos J. Donzelli, Martell Valencia, Alessandro Paggi, Ralph P. Kraft, Chiara Stuardi, Belinda J. Wilkes

Physics & Astronomy Faculty Publications

The environment of the high-redshift (z = 1.408), powerful radio-loud galaxy 3C 297 has several distinctive features of a galaxy cluster. Among them, a characteristic halo of hot gas revealed by Chandra X-ray observations. In addition, a radio map obtained with the Very Large Array shows a bright hotspot in the northwestern direction, created by the interaction of the active galactic nucleus (AGN) jet arising from 3C 297 with its environment. In the X-ray images, emission cospatial with the northwestern radio lobe is detected, and peaks at the position of the radio hotspot. The extended, complex X-ray emission observed …

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Stabilization Of Zero-Energy Skin Modes In Finite Non-Hermitian Lattices, Cem Yuce, Hamidreza Ramezani Dec 2022

Stabilization Of Zero-Energy Skin Modes In Finite Non-Hermitian Lattices, Cem Yuce, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

The zero energy of a one-dimensional semi-infinite non-Hermitian lattice with nontrivial spectral topology may disappear when we introduce boundaries to the system. While the corresponding zero-energy state can be considered as a quasi-edge state for the finite lattice with a long survival time, any small disruption (noise) in the initial form of the quasi-edge state can significantly shorten the survival time. Here, by tailoring the couplings at one edge we form an exceptional point allowing for a topological phase transition and the stabilization of the quasi-edge state in a finite-size lattice with open edges. Such a small modification in the …

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Optical Properties And Simulated X-Ray Near Edge Spectra For Y2o2s And Er Doped Y2o2s, Nicholas Dimakis, Eric Baldemar Rodriguez Jr., Kofi Nketia Ackaah-Gyasi, Madhab Pokhrel Dec 2022

Optical Properties And Simulated X-Ray Near Edge Spectra For Y2o2s And Er Doped Y2o2s, Nicholas Dimakis, Eric Baldemar Rodriguez Jr., Kofi Nketia Ackaah-Gyasi, Madhab Pokhrel

Physics & Astronomy Faculty Publications

The electronic and optical properties of Y2O2S and its Er+3 doped counterparts at various concentrations are analyzed using density functional theory (DFT) and simulated x-ray near edge (XANES) spectra. Our simulations are complemented by absorption experiments, which show Y2O2S:Er+3 light emissions in the visible and near infrared. These emissions correspond to Er f–f intraband transitions. We use DFT and DFT+U to calculate the band structure of the Y2O2S and its Er+3 doped counterparts, whereas optical properties are calculated using the independent particle approximation (IPA). The host Y2O2S optical properties are also calculated using the random phase approximation (RPA) and …

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Non-Hermitian Skin Effect In Two Dimensional Continuous Systems, Cem Yuce, Hamidreza Ramezani Dec 2022

Non-Hermitian Skin Effect In Two Dimensional Continuous Systems, Cem Yuce, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

An extensive number of the eigenstates can become exponentially localized at one boundary of nonreciprocal non-Hermitian systems. This effect is known as the non-Hermitian skin effect and has been studied mostly in tight-binding lattices. To extend the skin effect to continues systems beyond 1D, we introduce a quadratic imaginary vector potential in the continuous two dimensional Schr¨odinger equation. We find that inseparable eigenfunctions for separable nonreciprocal Hamiltonians appear under infinite boundary conditions. Introducing boundaries destroy them and hence they can only be used as quasistationary states in practice. We show that all eigenstates can be clustered at the point where …

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Dataset For Electronic And Optical Properties Of Y2o2s And Er Dopped Y2o2s Calculated Using Density Functional Theory And Simulated X-Ray Near Edge Spectra, Nicholas Dimakis, Eric Baldemar Rodriguez Jr., Kofi Nketia Ackaah-Gyasi, Madhab Pokhrel Dec 2022

Dataset For Electronic And Optical Properties Of Y2o2s And Er Dopped Y2o2s Calculated Using Density Functional Theory And Simulated X-Ray Near Edge Spectra, Nicholas Dimakis, Eric Baldemar Rodriguez Jr., Kofi Nketia Ackaah-Gyasi, Madhab Pokhrel

Physics & Astronomy Faculty Publications

The computational data presented in this paper refer to the research article “Optical properties and simulated x-ray near edge spectra for Y2O2S and Er doped Y2O2S”. We present the data used to calculate the structural, electronic, and optical properties of the Y2O2S and its Er+3 doped counterparts at various concentrations using density functional theory (DFT) and simulated X-ray near edge (XANES) spectra. We report electronic information from DFT and DFT+U generated from the Vienna Ab initio Simulation Package (VASP) using PAW pseudopotentials. We also report VASP calculated optical properties for the host Y2O2S using the independent particle approximation (IPA), the …

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All-Sky Search For Continuous Gravitational Waves From Isolated Neutron Stars Using Advanced Ligo And Advanced Virgo O3 Data, R. Abbott, H. Abe, M. G. Benjamin, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang Nov 2022

All-Sky Search For Continuous Gravitational Waves From Isolated Neutron Stars Using Advanced Ligo And Advanced Virgo O3 Data, R. Abbott, H. Abe, M. G. Benjamin, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We present results of an all-sky search for continuous gravitational waves which can be produced by spinning neutron stars with an asymmetry around their rotation axis, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. Four different analysis methods are used to search in a gravitational-wave frequency band from 10 to 2048 Hz and a first frequency derivative from −10−8 to 10−9  Hz/s. No statistically significant periodic gravitational-wave signal is observed by any of the four searches. As a result, upper limits on the gravitational-wave strain amplitude h0 are calculated. The best upper limits …

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Electromagnetism In Quark Matter At Intermediate Densities, Efrain J. Ferrer Nov 2022

Electromagnetism In Quark Matter At Intermediate Densities, Efrain J. Ferrer

Physics & Astronomy Faculty Publications

Several anomalous electromagnetic effects that can take place in quark matter at low temperatures and intermediate densities will be discussed. The anomalous transport properties of the spatially inhomogeneous phase of quark matter known as the Magnetic Dual Chiral Density Wave (MDCDW) phase will be reviewed. Going beyond mean-field approximation, it will be shown how linearly polarized electromagnetic waves that penetrate the MDCDW medium mix with the phonon fluctuations to give rise to two hybridized modes of propagation called axion polaritons. Finally, some possible implications of these results for the astrophysics of neutron stars will be indicated.

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Resolving Galactic Binaries Using A Network Of Space-Borne Gravitational Wave Detectors, Xue-Hao Zhang, Shao-Dong Zhao, Soumya D. Mohanty, Yu-Xiao Liu Nov 2022

Resolving Galactic Binaries Using A Network Of Space-Borne Gravitational Wave Detectors, Xue-Hao Zhang, Shao-Dong Zhao, Soumya D. Mohanty, Yu-Xiao Liu

Physics & Astronomy Faculty Publications

Extracting gravitational wave (GW) signals from individual Galactic binaries (GBs) against their self-generated confusion noise is a key data analysis challenge for space-borne detectors operating in the ≈0.1 to ≈10  mHz range. Given the likely prospect that there will be multiple such detectors, namely Laser Interferometer Space Antenna (LISA), Taiji, and Tianqin, with overlapping operational periods in the next decade, it is important to examine the extent to which the joint analysis of their data can benefit GB resolution and parameter estimation. To investigate this, we use realistic simulated LISA and Taiji data containing the set of 30×106 GBs used …

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Iterative Time-Domain Method For Resolving Multiple Gravitational Wave Sources In Pulsar Timing Array Data, Yi Qian Qian, Soumya D. Mohanty, Yan Wang Nov 2022

Iterative Time-Domain Method For Resolving Multiple Gravitational Wave Sources In Pulsar Timing Array Data, Yi Qian Qian, Soumya D. Mohanty, Yan Wang

Physics & Astronomy Faculty Publications

The sensitivity of ongoing searches for gravitational wave (GW) sources in the ultra-low-frequency regime (10(-9) Hz to 10(-7) Hz) using pulsar timing arrays (PTAs) will continue to increase in the future as more well-timed pulsars are added to the arrays. It is expected that next-generation radio telescopes, namely, the Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST) and the Square Kilometer Array (SKA), will grow the number of well-timed pulsars to O(10(3)). The higher sensitivity will result in greater distance reach for GW sources, uncovering multiple resolvable GW sources in addition to an unresolved population. Data analysis techniques that can search for …

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A Method To Solve One-Dimensional Nonlinear Fractional Differential Equation Using B-Polynomials, Md. Habibur Rahman, Muhammad I. Bhatti, Nicholas Dimakis Nov 2022

A Method To Solve One-Dimensional Nonlinear Fractional Differential Equation Using B-Polynomials, Md. Habibur Rahman, Muhammad I. Bhatti, Nicholas Dimakis

Physics & Astronomy Faculty Publications

In this article, the fractional Bhatti-Polynomial bases are applied to solve one-dimensional nonlinear fractional differential equations (NFDEs). We derive a semi-analytical solution from a matrix equation using an operational matrix which is constructed from the terms of the NFDE using Caputo’s fractional derivative of fractional B-polynomials (B-polys). The results obtained using the prescribed method agree well with the analytical and numerical solutions presented by other authors. The legitimacy of this method is demonstrated by using it to calculate the approximate solutions to four NFDEs. The estimated solutions to the differential equations have also been compared with other known numerical and …

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Which Countries Are Leading High-Impact Science In Astronomy?, Juan P. Madrid, Julie Steen Oct 2022

Which Countries Are Leading High-Impact Science In Astronomy?, Juan P. Madrid, Julie Steen

Physics & Astronomy Faculty Publications

Recent news reports claim that China is overtaking the United States and all other countries in scientific productivity and scientific impact. A straightforward analysis of high-impact papers in astronomy reveals that this is not true in our field. In fact, the United States continues to host, by a large margin, the authors that lead high-impact papers. Moreover, this analysis shows that 90% of all high-impact papers in astronomy are led by authors based in North America and Europe. That is, only about 10% of countries in the world host astronomers that publish “astronomy’s greatest hits".

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Targeted Search For The Kinematic Dipole Of The Gravitational-Wave Background, Adrian Ka-Wai Chung, Alexander C. Jenkins, Joseph D. Romano, Mairi Sakellariadou Oct 2022

Targeted Search For The Kinematic Dipole Of The Gravitational-Wave Background, Adrian Ka-Wai Chung, Alexander C. Jenkins, Joseph D. Romano, Mairi Sakellariadou

Physics & Astronomy Faculty Publications

There is growing interest in using current and future gravitational-wave interferometers to search for anisotropies in the gravitational-wave background. One guaranteed anisotropic signal is the kinematic dipole induced by our peculiar motion with respect to the cosmic rest frame, as measured in other full-sky observables such as the cosmic microwave background. Our prior knowledge of the amplitude and direction of this dipole is not explicitly accounted for in existing searches by LIGO/Virgo/KAGRA but could provide crucial information to help disentangle the sources which contribute to the gravitational-wave background. Here, we develop a targeted search pipeline which uses this prior knowledge …

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Diffraction-Free Beam Propagation At The Exceptional Point Of Non-Hermitian Glauber Fock Lattices, Cem Yuce, Hamidreza Ramezani Oct 2022

Diffraction-Free Beam Propagation At The Exceptional Point Of Non-Hermitian Glauber Fock Lattices, Cem Yuce, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

We construct localized beams in a non-Hermitian Glauber Fock (NGF) lattice of coupled waveguides and show that they can propagate for a long distance without almost no diffraction. We specifically obtain the diffraction-free beams in a finite NGF lattice at the exceptional point (EP) by using the exact eigenstates of the semi-infinite unidirectional NGF lattice. We provide a numerical approach to finding other lattices that are capable of supporting non-diffracting beams at EPs.

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On A Novel Approach To The Thermogravimetric Analysis Of Polymers: Polystyrene, Mircea Chipara, Karen Lozano, Dorina M. Chipara, Carlos Delgado, Victoria Padilla Sep 2022

On A Novel Approach To The Thermogravimetric Analysis Of Polymers: Polystyrene, Mircea Chipara, Karen Lozano, Dorina M. Chipara, Carlos Delgado, Victoria Padilla

Physics & Astronomy Faculty Publications

A novel equation that describes the temperature dependence of the residual mass fraction (as determined by thermogravimetric analysis) is derived, assuming that the dependence of the residual mass fraction on temperature has a sigmoidal shape. The equation allows the estimation of the sigmoidal activation energy solely from the experimental data at a single heating rate. The consistency with the isoconversional approach and the relationship between the Ozawa and sigmoidal activation energies are reported. The equation was successfully tested by the thermal degradation of atactic polystyrene at various heating rates. Both the thermograms and their derivatives are analyzed in detail.

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Search For Gravitational Waves From Scorpius X-1 With A Hidden Markov Model In O3 Ligo Data, R. Abbott, H. Abe, F. Acernese, K. Ackley, N. Adhikari, Michael G. Benjamin, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang Sep 2022

Search For Gravitational Waves From Scorpius X-1 With A Hidden Markov Model In O3 Ligo Data, R. Abbott, H. Abe, F. Acernese, K. Ackley, N. Adhikari, Michael G. Benjamin, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

Results are presented for a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to allow for spin wandering. This search improves on previous HMM-based searches of Laser Interferometer Gravitational-Wave Observatory data by including the orbital period in the search template grid, and by analyzing data from the latest (third) observing run. In the frequency range searched, from 60 to 500 Hz, we find no evidence of gravitational radiation. This is the most sensitive search for Scorpius X-1 using a HMM to date. For the most sensitive subband, starting at …

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Coupled Surface Plasmon–Phonon Polariton Nanocavity Arrays For Enhanced Mid-Infrared Absorption, Satya R. Kachiraju, Ivan Nekrashevich, Imtiaz Ahmad, Hira Farooq, Long Chang, Sangsik Kim, Myoung-Hwan Kim Sep 2022

Coupled Surface Plasmon–Phonon Polariton Nanocavity Arrays For Enhanced Mid-Infrared Absorption, Satya R. Kachiraju, Ivan Nekrashevich, Imtiaz Ahmad, Hira Farooq, Long Chang, Sangsik Kim, Myoung-Hwan Kim

Physics & Astronomy Faculty Publications

Resonant optical cavities are essential components in mid-infrared applications. However, typical film-type cavities require multilayer stacks with a micronthick spacer due to mid-infrared wavelengths, and their performance is limited by narrow frequency tunability and angular sensitivity. We propose and experimentally demonstrate the subwavelength-scale (≈��0/150) resonant nanocavity arrays that enhance the absorption spectrum of the device in the mid-infrared (10–12 microns) via excitation of coupled surface plasmon–phonon polaritons. The proposed metal–insulator–polar dielectric (gold–silicon–silicon carbide) structure supports a guided mode of the coupled surface polaritons in the lateral direction while vertically confining the mid-infrared wave

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Search For Continuous Gravitational Wave Emission From The Milky Way Center In O3 Ligo-Virgo Data, R. Abbott, H. Abe, F. Acernese, M. G. Benjamin, Teviet Creighton, Mario C. Diaz, F. Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang Aug 2022

Search For Continuous Gravitational Wave Emission From The Milky Way Center In O3 Ligo-Virgo Data, R. Abbott, H. Abe, F. Acernese, M. G. Benjamin, Teviet Creighton, Mario C. Diaz, F. Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We present a directed search for continuous gravitational wave (CW) signals emitted by spinning neutron stars located in the inner parsecs of the Galactic Center (GC). Compelling evidence for the presence of a numerous population of neutron stars has been reported in the literature, turning this region into a very interesting place to look for CWs. In this search, data from the full O3 LIGO-Virgo run in the detector frequency band [10,2000]  Hz have been used. No significant detection was found and 95% confidence level upper limits on the signal strain amplitude were computed, over the full search band, with …

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Search For Subsolar-Mass Binaries In The First Half Of Advanced Ligo’S And Advanced Virgo’S Third Observing Run, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Volker Quetschke, Wenhui Wang Aug 2022

Search For Subsolar-Mass Binaries In The First Half Of Advanced Ligo’S And Advanced Virgo’S Third Observing Run, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We report on a search for compact binary coalescences where at least one binary component has a mass between 0.2  M⊙ and 1.0  M⊙ in Advanced LIGO and Advanced Virgo data collected between 1 April 2019 1500 UTC and 1 October 2019 1500 UTC. We extend our previous analyses in two main ways: we include data from the Virgo detector and we allow for more unequal mass systems, with mass ratio q≥0.1. We do not report any gravitational-wave candidates. The most significant trigger has a false alarm rate of 0.14  yr−1. This implies an upper limit on the merger rate …

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Phase Transitions And Resilience Of The Magnetic Dual Chiral Density Wave Phase At Finite Temperature And Density, William Gyory, Vivian De La Incera Jul 2022

Phase Transitions And Resilience Of The Magnetic Dual Chiral Density Wave Phase At Finite Temperature And Density, William Gyory, Vivian De La Incera

Physics & Astronomy Faculty Publications

We study the phase transitions at finite temperature and density of the magnetic dual chiral density wave (MDCDW) phase. This spatially inhomogeneous phase emerges in cold, dense QCD in the presence of a strong magnetic field. Starting from the generalized Ginzburg-Landau (GL) expansion of the free energy, we derive several analytical formulas that enable fast numerical computation of the expansion coefficients to arbitrary order, allowing high levels of precision in the determination of the physical dynamical parameters, as well as in the transition curves in the temperature vs chemical potential plane at different magnetic fields. At magnetic fields and temperatures …

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