Astrophysics and Astronomy Commons^™

Inferring Binary Parameters With Dual-Line Gravitational Wave Detection From Tight Inspiraling Double Neutron Stars, Wen-Fan Feng, Jie-Wen Chen, Tan Liu, Yan Wang, Soumya D. Mohanty

Physics & Astronomy Faculty Publications

Neutron star (NS) binaries can be potentially intriguing gravitational wave sources, with both high- and low-frequency radiation from the possibly aspherical individual stars and the binary orbit, respectively. The successful detection of such a dual-line source could provide fresh insights into binary geometry and NS physics. In the absence of electromagnetic observations, we develop a strategy for inferring the spin-orbit misalignment angle using the tight dual-line double NS system under the spin-orbit coupling. Based on the four-year joint detection of a typical dual-line system with the Laser Interferometer Space Antenna and Cosmic Explorer, we find that the misalignment angle and …

Swarm Intelligence Methods For Extreme Mass Ratio Inspiral Search: First Application Of Particle Swarm Optimization, Xiao-Bo Zou, Soumya D. Mohanty, Hong-Gang Luo, Yu-Xiao Liu

Physics & Astronomy Faculty Publications

Swarm intelligence (SI) methods are nature-inspired metaheuristics for global optimization that exploit a coordinated stochastic search strategy by a group of agents. Particle swarm optimization (PSO) is an established SI method that has been applied successfully to the optimization of rugged high-dimensional likelihood functions, a problem that represents the main bottleneck across a variety of gravitational wave (GW) data analysis challenges. We present results from the first application of PSO to one of the most difficult of these challenges, namely the search for the Extreme Mass Ratio Inspiral (EMRI) in data from future spaceborne GW detectors such as LISA, Taiji, …

Axion-Polaritons In Quark Stars: A Possible Solution To The Missing Pulsar Problem, Efrain J. Ferrer, Vivian De La Incera

Physics & Astronomy Faculty Publications

This paper proposes an alternative mechanism to solve the so-called missing pulsar problem, a standing paradox between the theoretical expectations about the number of pulsars that should exist in the galaxy center of the Milky Way and their absence in the observations. The mechanism is based on the transformation of incident γ rays into hybridized modes, known as axion-polaritons, which can exist inside highly magnetized quark stars with a quark matter phase known as the magnetic dual chiral density wave phase. This phase, which is favored over several other dense matter phases candidates at densities a few times nuclear saturation …

Low Complexity Radio Frequency Interference Mitigation For Radio Astronomy Using Large Antenna Array, Zaid Bin Tariq, Teviet Creighton, Louis Percy Dartez, Naofal Al-Dhahir, Murat Torlak

Physics & Astronomy Faculty Publications

With the ongoing growth in radio communications, there is an increased contamination of radio astronomical source data, which hinders the study of celestial radio sources. In many cases, fast mitigation of strong radio frequency interference (RFI) is valuable for studying short lived radio transients so that the astronomers can perform detailed observations of celestial radio sources. The standard method to manually excise contaminated blocks in time and frequency makes the removed data useless for radio astronomy analyses. This motivates the need for better radio frequency interference (RFI) mitigation techniques for array of size M antennas. Although many solutions for mitigating …

Gwtc-2.1: Deep Extended Catalog Of Compact Binary Coalescences Observed By Ligo And Virgo During The First Half Of The 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

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶00 UTC and 1 October 2019 15∶00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used …

Advancements In Glitch Subtraction Systems For Enhancing Gravitational Wave Data Analysis: A Brief Review, Mohammad Abu Thaher Chowdhury

Physics & Astronomy Faculty Publications

Glitches are transitory noise artifacts that degrade the detection sensitivity and accuracy of interferometric observatories such as LIGO and Virgo in gravitational wave astronomy. Reliable glitch subtraction techniques are essential for separating genuine gravitational wave signals from background noise and improving the accuracy of astrophysical investigations. This review study summarizes the main glitch subtraction methods used in the industry. We talk about the efficacy of classic time-domain techniques in real-time applications, like matched filtering and regression methods. The robustness of frequency-domain approaches, such as wavelet transformations and spectral analysis, in detecting and mitigating non-stationary glitches is assessed. We also investigate …

Ultradeep Atca Imaging Of 47 Tucanae Reveals A Central Compact Radio Source, Alessandro Paduano, Arash Bahramian, James C. A. Miller-Jones, Adela Kawka, Tim J. Galvin, Liliana E. Rivera Sandoval, Sebastian Kamann, Jay Strader, Laura Chomiuk, Craig O. Heinke

Physics & Astronomy Faculty Publications

We present the results of an ultradeep radio continuum survey, containing ∼480 hr of observations, of the Galactic globular cluster 47 Tucanae with the Australia Telescope Compact Array. This comprehensive coverage of the cluster allows us to reach rms noise levels of 1.19 μJy beam−1 at 5.5 GHz, 940 nJy beam−1 at 9 GHz, and 790 nJy beam−1 in a stacked 7.25 GHz image. This is the deepest radio image of a globular cluster and the deepest image ever made with the Australia Telescope Compact Array. We identify ATCA J002405.702-720452.361, a faint (6.3 ± 1.2 μJy at 5.5 …

Gwtc-3: Compact Binary Coalescences Observed By Ligo And Virgo During The Second Part Of The Third Observing Run, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, F. Llamas, Soma Mukherjee, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

The third Gravitational-Wave Transient Catalog (GWTC-3) describes signals detected with Advanced LIGO and Advanced Virgo up to the end of their third observing run. Updating the previous GWTC-2.1, we present candidate gravitational waves from compact binary coalescences during the second half of the third observing run (O3b) between 1 November 2019, 15∶00 Coordinated Universal Time (UTC) and 27 March 2020, 17∶00 UTC. There are 35 compact binary coalescence candidates identified by at least one of our search algorithms with a probability of astrophysical origin ��astro>0.5. Of these, 18 were previously reported as low-latency public alerts, and 17 are reported …

Gwtc-3: Compact Binary Coalescences Observed By Ligo And Virgo During The Second Part Of The Third Observing Run, R. Abbott, T. Abbott, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Wenhui Wang, Francisco Llamas

Physics & Astronomy Faculty Publications

The third Gravitational-Wave Transient Catalog (GWTC-3) describes signals detected with Advanced LIGO and Advanced Virgo up to the end of their third observing run. Updating the previous GWTC-2.1, we present candidate gravitational waves from compact binary coalescences during the second half of the third observing run (O3b) between 1 November 2019, 15 ∶ 00 Coordinated Universal Time (UTC) and 27 March 2020, 17 ∶ 00 UTC. There are 35 compact binary coalescence candidates identified by at least one of our search algorithms with a probability of astrophysical origin p astro > 0.5 . Of these, 18 were previously reported as low-latency …

Wallaby Pre-Pilot Survey: Ultra-Diffuse Galaxies In The Eridanus Supergroup, B.-Q. For, K. Spekkens, L. Staveley-Smith, K. Bekki, A. Karunakaran, B. Catinella, Bärbel S. Koribalski, K. Lee-Waddell, Juan P. Madrid, C. Murugeshan

Physics & Astronomy Faculty Publications

We present a pilot study of the atomic neutral hydrogen gas (H I) content of ultra-diffuse galaxy (UDG) candidates. In this paper, we use the pre-pilot Eridanus field data from the Widefield ASKAP L-band Legacy All-sky Blind Survey to search for H I in UDG candidates found in the Systematically Measuring Ultra-diffuse Galaxies survey (SMUDGes). We narrow down to 78 SMUDGes UDG candidates within the maximum radial extents of the Eridanus subgroups for this study. Most SMUDGes UDGs candidates in this study have effective radii smaller than 1.5 kpc and thus fail to meet the defining size threshold. We …

Teaching Introductory Physics In The Context Of Personal And Societal Issues Of The Covid-19 Pandemic, Guang Zeng, Liang Zeng

Physics & Astronomy Faculty Publications

This paper reports on introductory physics instruction contextualized in terms of coronavirus-related personal and societal issues. Students in this descriptive qualitative study gained a strong grasp of a range of physics concepts associated with the nature and mechanisms of the spread of the coronavirus, such as projectile motion, air convection, Reynolds number, and Brownian motion; additionally, they were able to discuss the application of physics relevant to the N95 face masks. Students found this pedagogical approach engaging, as shown in their reflective writing.

Analytic Distribution Of The Optimal Cross-Correlation Statistic For Stochastic Gravitational-Wave-Background Searches Using Pulsar Timing Arrays, ‪Jeffrey S. Hazboun, Patrick M. Meyers, Joseph D. Romano, Xavier Siemens, Anne M. Archibald

Physics & Astronomy Faculty Publications

We show via both analytical calculation and numerical simulation that the optimal cross-correlation statistic (OS) for stochastic gravitational-wave-background (GWB) searches using data from pulsar timing arrays follows a generalized chi-squared (GX2) distribution—i.e., a linear combination of chi-squared distributions with coefficients given by the eigenvalues of the quadratic form defining the statistic. This observation is particularly important for calculating the frequentist statistical significance of a possible GWB detection, which depends on the exact form of the distribution of the OS signal-to-noise ratio ρˆ ≡ Aˆ 2 gw=σ0 in the absence of GW-induced cross correlations (i.e., the null distribution). Previous discussions of …

Employing A Fractional Basis Set To Solve Nonlinear Multidimensional Fractional Differential Equations, Md. Habibur Rahman, Muhammad I. Bhatti, Nicholas Dimakis

Physics & Astronomy Faculty Publications

Fractional-order partial differential equations have gained significant attention due to their wide range of applications in various fields. This paper employed a novel technique for solving nonlinear multidimensional fractional differential equations by means of a modified version of the Bernstein polynomials called the Bhatti-fractional polynomials basis set. The method involved approximating the desired solution and treated the resulting equation as a matrix equation. All fractional derivatives are considered in the Caputo sense. The resulting operational matrix was inverted, and the desired solution was obtained. The effectiveness of the method was demonstrated by solving two specific types of nonlinear multidimensional fractional …

Broadband Quantum Enhancement Of The Ligo Detectors With Frequency-Dependent Squeezing, D. Ganapathy, W. Jia, M. Nakano, V. Xu, N. Aritomi, T. Cullen, N. Kijbunchoo, S. E. Dwyer, Francisco Llamas, Volker Quetschke

Physics & Astronomy Faculty Publications

Quantum noise imposes a fundamental limitation on the sensitivity of interferometric gravitational-wave detectors like LIGO, manifesting as shot noise and quantum radiation pressure noise. Here, we present the first realization of frequency-dependent squeezing in full-scale gravitational-wave detectors, resulting in the reduction of both shot noise and quantum radiation pressure noise, with broadband detector enhancement from tens of hertz to several kilohertz. In the LIGO Hanford detector, squeezing reduced the detector noise amplitude by a factor of 1.6 (4.0 dB) near 1 kHz; in the Livingston detector, the noise reduction was a factor of 1.9 (5.8 dB). These improvements directly impact …

A Framework To Validate Fluorescently Labeled Dna-Binding Proteins For Single-Molecule Experiments, Miranda Molina, Lindsey E. Way, Zhongqing Ren, Qin Liao, Bianca Guerra, Brandon Shields, Xindan Wang, Hyeongjun Kim

Physics & Astronomy Faculty Publications

Highlights

• KCK tag can alter protein properties both quantitatively and qualitatively

• Electrostatic interactions between the KCK tag and DNA contribute to the artifacts

• Adding a short peptide tag to ParB protein does not lead to its in vivo changes

• Single-molecule DNA flow-stretching assay can detect protein property changes

Motivation

Single-molecule fluorescence microscopy has been extensively used in modern biology to define the molecular action of proteins. Appending short peptide tags is a common strategy to enhance fluorescence labeling. Here, we evaluate the impact of a commonly used tag, the lysine-cysteine-lysine (KCK) tag, on protein behavior in single-molecule DNA flow-stretching assay, …

A Framework To Validate Fluorescently Labeled Dna-Binding Proteins For Single-Molecule Experiments, Miranda L. Molina, Lindsey E. Way, Zhongqing Ren, Qin Liao, Bianca Guerra, Brandon Shields, Xindan Wang, Hyeongjun Kim

Physics & Astronomy Faculty Publications

Due to the enhanced labeling capability of maleimide-based fluorescent probes, lysine-cysteine-lysine (KCK) tags are frequently added to proteins for visualization. In this study, we employed an in vitro single-molecule DNA flow-stretching assay as a sensitive way to assess the impact of the KCK tag on the property of DNA-binding proteins. Using Bacillus subtilis ParB as an example, we show that, although no noticeable changes were detected by in vivo fluorescence imaging and chromatin immunoprecipitation (ChIP) assays, the KCK tag substantially altered ParB's DNA compaction rates and its response to nucleotide binding and to the presence of the specific sequence (parS) …

Fast-Askap Synergy: Quantifying Coexistent Tidal And Ram Pressure Strippings In The Ngc 4636 Group, Xuchen Lin, Jing Wang, Virginia Kilborn, Eric W. Peng, Luca Cortese, Alessandro Boselli, Ze-Zhong Liang, Bumhyun Lee, Dong Yang, Juan P. Madrid

Physics & Astronomy Faculty Publications

Combining new H I data from a synergetic survey of Australian Square Kilometre Array Pathfinder (ASKAP) Widefield ASKAP L-band Legacy All-sky Blind surveY and Five-hundred-meter Aperture Spherical radio Telescope with the Arecibo Legacy Fast ALFA data, we study the effect of ram pressure and tidal interactions in the NGC 4636 group. We develop two parameters to quantify and disentangle these two effects on gas stripping in H I-bearing galaxies: the strength of external forces at the optical-disk edge, and the outside-in extents of H I-disk stripping. We find that gas stripping is widespread in this group, affecting 80% of H …

The Accumulation And Growth Of Pseudomonas Aeruginosa On Surfaces Is Modulated By Surface Mechanics Via Cyclic-Di-Gmp Signaling, Liyun Wang, Yu-Chern Wong, Joshua M. Correira, Megan Wancura, Chris J. Geiger, Shanice S. Webster, Ahmed Touhami, Benjamin J. Butler, George A. O’Toole, Richard M. Langford

Physics & Astronomy Faculty Publications

Attachment of bacteria onto a surface, consequent signaling, and accumulation and growth of the surface-bound bacterial population are key initial steps in the formation of pathogenic biofilms. While recent reports have hinted that surface mechanics may affect the accumulation of bacteria on that surface, the processes that underlie bacterial perception of surface mechanics and modulation of accumulation in response to surface mechanics remain largely unknown. We use thin and thick hydrogels coated on glass to create composite materials with different mechanics (higher elasticity for thin composites; lower elasticity for thick composites) but with the same surface adhesivity and chemistry. The …

Search For Subsolar-Mass Black Hole Binaries In The Second Part Of Advanced Ligo’S And Advanced Virgo’S Third Observing Run, R. Abbott, H. Abe, F. Acernese, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We describe a search for gravitational waves from compact binaries with at least one component with mass 0.2 –1.0M⊙ and mass ratio q ≥ 0.1 in Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo data collected between 2019 November 1, 15:00 UTC and 2020 March 27, 17:00 UTC. No signals were detected. The most significant candidate has a false alarm rate of 0.2yr−1 ⁠. We estimate the sensitivity of our search over the entirety of Advanced LIGO’s and Advanced Virgo’s third observing run, and present the most stringent limits to date on the merger rate of binary black holes …

Rubin Observatory Lsst Transients And Variable Stars Roadmap, Kelly M. Hambleton, Federica B. Bianco, Rachel Street, Keaton Bell, David Buckley, Melissa Graham, Nina Hernitschek, Michael B. Lund, Elena Mason, Liliana Rivera Sandoval

Physics & Astronomy Faculty Publications

The Vera C. Rubin Legacy Survey of Space and Time (LSST) holds the potential to revolutionize time domain astrophysics, reaching completely unexplored areas of the Universe and mapping variability time scales from minutes to a decade. To prepare to maximize the potential of the Rubin LSST data for the exploration of the transient and variable Universe, one of the four pillars of Rubin LSST science, the Transient and Variable Stars Science Collaboration, one of the eight Rubin LSST Science Collaborations, has identified research areas of interest and requirements, and paths to enable them. While our roadmap is ever-evolving, this document …

A Review On Antibacterial Activity Of Nanoparticles, Badr-Edine Sadoq, Mohammed Reda Britel, Adel Bouajaj, Ramzi Maâlej, Ahmed Touhami, Marwa Abid, Hanen Douiri, Fakhita Touhami, Amal Maurady

Physics & Astronomy Faculty Publications

The increasing resistance of bacteria to antibiotic agents is a main global public health problem. The use of nanoparticles is one of the promising ways to overcome microbial resistance to antimicrobial agents. Metal nanoparticles are increasingly used to target bacterial strains. Advances in nanotechnology, in particular the ability to synthesize nanoparticles of specific size and shape, are likely to lead to the development of new antibacterial agents. The antibacterial activities of nanoparticles are largely influenced by their sizes and large surface area/mass ratio. The antibacterial mechanisms of nanoparticles are poorly understood, but the currently accepted mechanisms include oxidative stress induction, …

Conformational Landscapes Of Symmetrically Fluorine-Substituted Benzoic Acids Ii: Calculations And Measurements For The Rotational Spectrum And Structure Of 3,4,5-Trifluorobenzoic Acid, Jingling Hong, Alitza Gracia, Savannah Romero, Mingfei Zhou, Wei Lin, Weixing Li

Physics & Astronomy Faculty Publications

Calculations on the structure of 3,4,5-trifluorobenzoic acid were made using the Gaussian 16 program. The potential energy surfaces were scanned along CCCO and OCOH dihedral angles at the B3LYP/6-311G level to analyze its conformational landscape. Two conformations were identified and reoptimized at the B3LYP/aug-cc-pVTZ level. The result indicates that 3,4,5-trifluorobenzoic acid prefers a planar structure in its global minimum conformation. The pure rotational spectra of 3,4,5-trifluorobenzoic acid were measured in the frequency range of 6 – 12.5 GHz using a chirped pulse Fourier transform microwave (CP-FTMW) spectrometer. The spectra of the parent, seven 13C, and one deuterium singly substituted isotopologues …

Conformational Landscapes Of Symmetrically Fluorine-Substituted Benzoic Acids I: Microwave Spectroscopic And Theoretical Studies On 3,5-Difluorobenzoic Acid, Alitza Gracia, Jingling Hong, Rebakah Arismendi, Mingfei Zhou, Weixing Li, Wei Lin

Physics & Astronomy Faculty Publications

We report our combined theoretical and spectroscopic studies on 3,5-difluorobenzoic acid. Using a chirped pulse Fourier transform microwave (CP-FTMW) spectrometer, we recorded and analyzed the rotational spectrum spanning the frequency range of 6 – 12.5 GHz. Quantum chemical calculations were employed to analyze the conformational changes and landscapes of 3,5-difluorobenzoic acid. These calculations focused on studying the potential energy surfaces along the CCCO and OCOH dihedral angles at the B3LYP/6-311G level. Based on the computational results, we identified the global minimum conformer 1 as well as the local minimum conformer 2. We discussed and interpreted the geometric structures of the …

Search For Gravitational Waves Associated With Fast Radio Bursts Detected By Chime/Frb During The Ligo–Virgo Observing Run O3a, R. Abbott, T. Abbott, F. Acernese, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We search for gravitational-wave (GW) transients associated with fast radio bursts (FRBs) detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst Project, during the first part of the third observing run of Advanced LIGO and Advanced Virgo (2019 April 1 15:00 UTC–2019 October 1 15:00 UTC). Triggers from 22 FRBs were analyzed with a search that targets both binary neutron star (BNS) and neutron star–black hole (NSBH) mergers. A targeted search for generic GW transients was conducted on 40 FRBs. We find no significant evidence for a GW association in either search. Given the large uncertainties in the …

Effects Of Spin-Orbit Coupling On Gravitational Waveforms From A Triaxial Nonaligned Neutron Star In A Binary System, Wen-Fan Feng, Tan Liu, Jie-Wen Che, Yan Wang, Soumya D. Mohanty

Physics & Astronomy Faculty Publications

Spinning neutron stars (NSs) can emit continuous gravitational waves (GWs) that carry a wealth of information about the compact object. If such a signal is detected, it will provide us with new insight into the physical properties of matter under extreme conditions. According to binary population synthesis simulations, future space-based GW detectors, such as LISA and TianQin, can potentially detect some double NSs in tight binaries with orbital periods shorter than 10 minutes. The possibility of a successful directed search for continuous GWs from the spinning NS in such a binary system identified by LISA/TianQin will be significantly increased with …

Powerful Radio Sources In The Southern Sky. Ii. A Swift X-Ray Perspective, Francesco Massaro, S. V. White, A. Paggi, A. Jimenez-Gallardo, Juan P. Madrid, C. Mazzucchelli, W. R. Forman, A. Capetti, C. C. Cheung

Physics & Astronomy Faculty Publications

We recently constructed the G4Jy-3CRE, a catalog of extragalactic radio sources based on the GLEAM 4-Jy (G4Jy) sample, with the aim of increasing the number of powerful radio galaxies and quasars with similar selection criteria to those of the revised release of the Third Cambridge Catalog (3CR). The G4Jy-3CRE consists of a total of 264 radio sources mainly visible from the Southern Hemisphere. Here, we present an initial X-ray analysis of 89 G4Jy-3CRE radio sources with archival X-ray observations from the Neil Gehrels Swift Observatory. We reduced a total of 624 Swift observations, for about 0.9 Ms of integrated exposure …

Exploring The Capabilities Of Gibbs Sampling In Pulsar Timing Arrays, Nima Laal, William G. Lamb, Joseph D. Romano, Xavier Siemens, Stephen R. Taylor, Rutger Van Haasteren

Physics & Astronomy Faculty Publications

We explore the use of Gibbs sampling in estimating the noise properties of individual pulsars and illustrate its effectiveness using the NANOGrav 11-year dataset. We find that Gibbs sampling noise modeling (GM) is more efficient than the current standard Bayesian techniques (SM) for single pulsar analyses by yielding model parameter posteriors with average effective-sample-size ratio (GM/SM) of 6 across all parameters and pulsars. Furthermore, the output of GM contains posteriors for the Fourier coefficients that can be used to characterize the underlying red noise process of any pulsar’s timing residuals, which are absent in current implementations of SM. Through simulations, …

Axion-Polaritons In The Magnetic Dual Chiral Density Wave Phase Of Dense Qcd, Efrain J. Ferrer, Vivian De La Incera

Physics & Astronomy Faculty Publications

We investigate the propagation of electromagnetic radiation in the magnetic dual chiral density wave (MDCDW) phase of dense quark matter. Considering the theory of low-energy fluctuations in this phase, we show how linearly polarized photons reaching the MDCDW medium couple to the fluctuation field to produce two hybridized modes of propagation that we call in analogy with similar phenomenon in condensed matter physics axion polaritons, one of them being gapless and the other gapped. The gapped mode's gap is proportional to the background magnetic field and inversely proportional to the amplitude of the inhomogeneous condensate. The generation of axion …

Hellings And Downs Correlation Of An Arbitrary Set Of Pulsars, Bruce Allen, Joseph D. Romano

Physics & Astronomy Faculty Publications

Pulsar timing arrays (PTAs) detect gravitational waves (GWs) via the correlations they induce in the arrival times of pulses from different pulsars. We assume that the GWs are described by a Gaussian ensemble, which models the confusion noise produced by expected PTA sources. The mean correlation h2μu(γ) as a function of the angle γ between the directions to two pulsars was predicted by Hellings and Downs in 1983. The variance σ2tot(γ) in this correlation was recently calculated [B. Allen, Variance of the Hellings-Downs correlation, Phys. Rev. D 107, 043018 (2023)] for a single noise-free pulsar pair at angle γ, …

Hellings And Downs Correlation Of An Arbitrary Set Of Pulsars, Bruce Allen, Joseph D. Romano

Physics & Astronomy Faculty Publications

Pulsar timing arrays (PTAs) detect gravitational waves (GWs) via the correlations they induce in the arrival times of pulses from different pulsars. We assume that the GWs are described by a Gaussian ensemble, which models the confusion noise produced by expected PTA sources. The mean correlation h2μu(γ) as a function of the angle γ between the directions to two pulsars was predicted by Hellings and Downs in 1983. The variance σ2tot(γ) in this correlation was recently calculated [B. Allen, Variance of the Hellings-Downs correlation, Phys. Rev. D 107, 043018 (2023)] for a single noise-free pulsar pair at angle γ, …