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Articles 1 - 28 of 28
Full-Text Articles in Physical Sciences and Mathematics
Mapping Gravitational-Wave Backgrounds Of Arbitrary Polarisation Using Pulsar Timing Arrays, Jonathan Gair, Joseph D. Romano, Stephen R. Taylor
Mapping Gravitational-Wave Backgrounds Of Arbitrary Polarisation Using Pulsar Timing Arrays, Jonathan Gair, Joseph D. Romano, Stephen R. Taylor
Physics and Astronomy Faculty Publications and Presentations
We extend our previous work on mapping gravitational-wave backgrounds using techniques borrowed from the analysis of cosmic microwave background data to backgrounds which have non-general-relativity (non-GR) polarisations. Our analysis and results are presented in the context of pulsar timing array observations, but the overarching methods are general, and can be easily applied to LIGO or eLISA observations using appropriately modified response functions. Analytic expressions for the pulsar timing response to gravitational waves with non-GR polarisation are given for each mode of a spin-weighted spherical-harmonic decomposition of the background, which permit the signal to be mapped across the sky to any …
Coherent Network Analysis For Continuous Gravitational Wave Signals In A Pulsar Timing Array: Pulsar Phases As Extrinsic Parameters, Yan Wang, Soumya D. Mohanty, F. A. Jenet
Coherent Network Analysis For Continuous Gravitational Wave Signals In A Pulsar Timing Array: Pulsar Phases As Extrinsic Parameters, Yan Wang, Soumya D. Mohanty, F. A. Jenet
Physics and Astronomy Faculty Publications and Presentations
Supermassive black hole binaries are one of the primary targets of gravitational wave (GW) searches using pulsar timing arrays (PTAs). GW signals from such systems are well represented by parameterized models, allowing the standard Generalized Likelihood Ratio Test (GLRT) to be used for their detection and estimation. However, there is a dichotomy in how the GLRT can be implemented for PTAs: there are two possible ways in which one can split the set of signal parameters for semi-analytical and numerical extremization. The straightforward extension of the method used for continuous signals in ground-based GW searches, where the so-called pulsar phase …
The Nanograv Nine-Year Data Set: Observations Arrival Time Measurements And Analysis Of 37 Millisecond Pulsars, Z. Arzoumanian, Zaven Arzoumanian, Adam Brazier, Sarah Burke-Spolaor, Sydney Chamberlin, Shami Chatterjee, Brian Christy, James M. Cordes, Neil Cornish, Kathryn Crowter, Paul B. Demorest, Timothy Dolch, Justin A. Ellis, Robert D. Ferdman, Emmanuel Fonseca, Nathan Garver-Daniels, Marjorie E. Gonzalez, Fredrick A. Jenet, Glenn Jones, Megan L. Jones, Victoria M. Kaspi, Michael Koop, Michael T. Lam, T. Joseph W. Lazio, Lina Levin, Andrea N. Lommen, Duncan R. Lorimer, Jing Luo, Ryan S. Lynch, Dustin Madison
The Nanograv Nine-Year Data Set: Observations Arrival Time Measurements And Analysis Of 37 Millisecond Pulsars, Z. Arzoumanian, Zaven Arzoumanian, Adam Brazier, Sarah Burke-Spolaor, Sydney Chamberlin, Shami Chatterjee, Brian Christy, James M. Cordes, Neil Cornish, Kathryn Crowter, Paul B. Demorest, Timothy Dolch, Justin A. Ellis, Robert D. Ferdman, Emmanuel Fonseca, Nathan Garver-Daniels, Marjorie E. Gonzalez, Fredrick A. Jenet, Glenn Jones, Megan L. Jones, Victoria M. Kaspi, Michael Koop, Michael T. Lam, T. Joseph W. Lazio, Lina Levin, Andrea N. Lommen, Duncan R. Lorimer, Jing Luo, Ryan S. Lynch, Dustin Madison
Physics and Astronomy Faculty Publications and Presentations
We present high-precision timing observations spanning up to nine years for 37 millisecond pulsars monitored with the Green Bank and Arecibo radio telescopes as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We describe the observational and instrumental setups used to collect the data, and methodology applied for calculating pulse times of arrival; these include novel methods for measuring instrumental offsets and characterizing low signal-to-noise ratio timing results. The time of arrival data are fit to a physical timing model for each source, including terms that characterize time-variable dispersion measure and frequency-dependent pulse shape evolution. In …
On The Disk Wind Mass Loss Rates In Qsos, Nicolas A. Pereyra
On The Disk Wind Mass Loss Rates In Qsos, Nicolas A. Pereyra
Physics and Astronomy Faculty Publications and Presentations
We derive here a relatively simple expression for the total wind mass loss rates in QSOs within the accretion disk wind scenario. We show that the simple expression derived here for QSO disk wind mass loss rate is in a very good agreement with the more “exact” values obtained through significantly more complex and detailed numerically intensive 2.5D time-dependent simulations. Additionally we show that for typical QSO parameters, the disk itself will be emitting mostly in the UV/optical spectrum, in turn implying that the X-ray emission from QSOs likely is produced through some physical mechanism acting at radii smaller than …
Searches For Continuous Gravitational Waves From Nine Young Supernova Remnants, J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Ain, P. Ajith, A. Alemic, B. Allen, A. Allocca, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. S. Areeda, S. Ast
Searches For Continuous Gravitational Waves From Nine Young Supernova Remnants, J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Ain, P. Ajith, A. Alemic, B. Allen, A. Allocca, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. S. Areeda, S. Ast
Physics and Astronomy Faculty Publications and Presentations
We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3-25.3 days using the matched-filtering -statistic. We found …
On The Formation And Evolution Of The First Be Star In A Black Hole Binary Mwc 656, M. Grudzinska, K. Belczynski, J. Casares, S. E. De Mink, J. Ziolkowski, I. Negueruela, M. Ribó, I. Ribas, J. M. Paredes, A. Herrero, M. Benacquista
On The Formation And Evolution Of The First Be Star In A Black Hole Binary Mwc 656, M. Grudzinska, K. Belczynski, J. Casares, S. E. De Mink, J. Ziolkowski, I. Negueruela, M. Ribó, I. Ribas, J. M. Paredes, A. Herrero, M. Benacquista
Physics and Astronomy Faculty Publications and Presentations
We find that the formation of MWC 656 (the first Be binary containing a black hole) involves a common envelope phase and a supernova explosion. This result supports the idea that a rapidly rotating Be star can emerge out of a common envelope phase, which is very intriguing because this evolutionary stage is thought to be too fast to lead to significant accretion and spin up of the B star.We predict ~10-100 of B-BH binaries to currently reside in the Galactic disc, among which around 1/3 contain a Be star, but there is only a small chance to observe a …
Pulsar J0453+1559: A Double Neutron Star System With A Large Mass Asymmetry, J. G. Martinez, K. Stovall, P. C.C. Freire, J. S. Deneva, F. A. Jenet, M. A. Mclaughlin, M. Bagchi, S. D. Bates, A. Ridolfi
Pulsar J0453+1559: A Double Neutron Star System With A Large Mass Asymmetry, J. G. Martinez, K. Stovall, P. C.C. Freire, J. S. Deneva, F. A. Jenet, M. A. Mclaughlin, M. Bagchi, S. D. Bates, A. Ridolfi
Physics and Astronomy Faculty Publications and Presentations
To understand the nature of supernovae and neutron star (NS) formation, as well as binary stellar evolution and their interactions, it is important to probe the distribution of NS masses. Until now, all double NS (DNS) systems have been measured as having a mass ratio close to unity (q ≥ 0.91). Here, we report the measurement of the individual masses of the 4.07-day binary pulsar J0453+1559 from measurements of the rate of advance of periastron and Shapiro delay: the mass of the pulsar is Mp = 1.559 � 0.005 Mo and that of its companion is Mo; q = 0.75. …
Arecibo Pulsar Survey Using Alfa. Iv. Mock Spectrometer Data Analysis Survey Sensitivity And The Discovery Of 40 Pulsars, P. Lazarus, A. Brazier, J. W.T. Hessels, C. Karako-Argaman, V. M. Kaspi, R. Lynch, E. Madsen, C. Patel, S. M. Ransom, P. Scholz, J. Swiggum, W. W. Zhu, B. Allen, S. Bogdanov, F. Camilo, F. Cardoso, S. Chatterjee, J. M. Cordes, F. Crawford, J. S. Deneva, R. Ferdman, P. C.C. Freire, F. A. Jenet, B. Knispel, K. J. Lee, J. Van Leeuwen, D. R. Lorimer, A. G. Lyne, M. A. Mclaughlin, X. Siemens
Arecibo Pulsar Survey Using Alfa. Iv. Mock Spectrometer Data Analysis Survey Sensitivity And The Discovery Of 40 Pulsars, P. Lazarus, A. Brazier, J. W.T. Hessels, C. Karako-Argaman, V. M. Kaspi, R. Lynch, E. Madsen, C. Patel, S. M. Ransom, P. Scholz, J. Swiggum, W. W. Zhu, B. Allen, S. Bogdanov, F. Camilo, F. Cardoso, S. Chatterjee, J. M. Cordes, F. Crawford, J. S. Deneva, R. Ferdman, P. C.C. Freire, F. A. Jenet, B. Knispel, K. J. Lee, J. Van Leeuwen, D. R. Lorimer, A. G. Lyne, M. A. Mclaughlin, X. Siemens
Physics and Astronomy Faculty Publications and Presentations
The on-going Arecibo Pulsar-ALFA (PALFA) survey began in 2004 and is searching for radio pulsars in the Galactic plane at 1.4 GHz. Here we present a comprehensive description of one of its main data reduction pipelines that is based on the PRESTO software and includes new interference-excision algorithms and candidate selection heuristics. This pipeline has been used to discover 40 pulsars, bringing the surveys discovery total to 144 pulsars. Of the new discoveries, eight are millisecond pulsars (MSPs; P 10 ms) and one is a Fast Radio Burst (FRB). This pipeline has also re-detected 188 previously known pulsars, 60 of …
Depth-Resolved Multispectral Sub-Surface Imaging Using Multifunctional Upconversion Phosphors With Paramagnetic Properties, Zaven Ovanesyan, L. Christopher Mimun, Gangadharan Ajith Kumar, Brian G. Yust, Chamath Dannongoda, Karen S. Martirosyan, Dhiraj K. Sardar
Depth-Resolved Multispectral Sub-Surface Imaging Using Multifunctional Upconversion Phosphors With Paramagnetic Properties, Zaven Ovanesyan, L. Christopher Mimun, Gangadharan Ajith Kumar, Brian G. Yust, Chamath Dannongoda, Karen S. Martirosyan, Dhiraj K. Sardar
Physics and Astronomy Faculty Publications and Presentations
Molecular imaging is very promising technique used for surgical guidance, which requires advancements related to properties of imaging agents and subsequent data retrieval methods from measured multispectral images. In this article, an upconversion material is introduced for subsurface near-infrared imaging and for the depth recovery of the material embedded below the biological tissue. The results confirm significant correlation between the analytical depth estimate of the material under the tissue and the measured ratio of emitted light from the material at two different wavelengths. Experiments with biological tissue samples demonstrate depth resolved imaging using the rare earth doped multifunctional phosphors. In …
Nanograv Constraints On Gravitational Wave Bursts With Memory, Z. Arzoumanian, A. Brazier, S. Burke-Spolaor, S. J. Chamberlin, S. Chatterjee, B. Christy, J. M. Cordes, N. J. Cornish, P. B. Demorest, X. Deng, T. Dolch, J. A. Ellis, R. D. Ferdman, E. Fonseca, N. Garver-Daniels, F. Jenet, G. Jones, V. M. Kaspi, M. Koop, M. T. Lam, T. J.W. Lazio, L. Levin, A. N. Lommen, D. R. Lorimer, J. Luo, R. S. Lynch, D. R. Madison, M. A. Mclaughlin, S. T. Mcwilliams, D. J. Nice
Nanograv Constraints On Gravitational Wave Bursts With Memory, Z. Arzoumanian, A. Brazier, S. Burke-Spolaor, S. J. Chamberlin, S. Chatterjee, B. Christy, J. M. Cordes, N. J. Cornish, P. B. Demorest, X. Deng, T. Dolch, J. A. Ellis, R. D. Ferdman, E. Fonseca, N. Garver-Daniels, F. Jenet, G. Jones, V. M. Kaspi, M. Koop, M. T. Lam, T. J.W. Lazio, L. Levin, A. N. Lommen, D. R. Lorimer, J. Luo, R. S. Lynch, D. R. Madison, M. A. Mclaughlin, S. T. Mcwilliams, D. J. Nice
Physics and Astronomy Faculty Publications and Presentations
Among efforts to detect gravitational radiation, pulsar timing arrays are uniquely poised to detect \"memory\" signatures, permanent perturbations in spacetime from highly energetic astrophysical events such as mergers of supermassive black hole binaries. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) observes dozens of the most stable millisecond pulsars using the Arecibo and Green Bank radio telescopes in an effort to study, among other things, gravitational wave memory. We herein present the results of a search for gravitational wave bursts with memory (BWMs) using the first five years of NANOGrav observations. We develop original methods for dramatically speeding up …
Dna Cyclization And Looping In The Wormlike Limit: Normal Modes And The Validity Of The Harmonic Approximation, Stefan M. Giovan, Andreas Hanke, Stephen D. Levene
Dna Cyclization And Looping In The Wormlike Limit: Normal Modes And The Validity Of The Harmonic Approximation, Stefan M. Giovan, Andreas Hanke, Stephen D. Levene
Physics and Astronomy Faculty Publications and Presentations
For much of the last three decades, Monte Carlo-simulation methods have been the standard approach for accurately calculating the cyclization probability, J, or J factor, for DNA models having sequence-dependent bends or inhomogeneous bending flexibility. Within the last 10 years approaches based on harmonic analysis of semi-flexible polymer models have been introduced, which offer much greater computational efficiency than Monte Carlo techniques. These methods consider the ensemble of molecular conformations in terms of harmonic fluctuations about a well-defined elastic-energy minimum. However, the harmonic approximation is only applicable for small systems, because the accessible conformation space of larger systems is increasingly …
Phase-Coherent Mapping Of Gravitational-Wave Backgrounds Using Ground-Based Laser Interferometers, Joseph D. Romano, Stephen R. Taylor, Neil Cornish, Jonathan Gair, Chiara M. F. Mingarelli, Rutger Van Haasteren
Phase-Coherent Mapping Of Gravitational-Wave Backgrounds Using Ground-Based Laser Interferometers, Joseph D. Romano, Stephen R. Taylor, Neil Cornish, Jonathan Gair, Chiara M. F. Mingarelli, Rutger Van Haasteren
Physics and Astronomy Faculty Publications and Presentations
We extend the formalisms developed in Gair et al. [1] and Cornish and van Haasteren [2] to create maps of gravitational-wave backgrounds using a network of ground-based laser interferometers. We show that in contrast to pulsar timing arrays, which are insensitive to the curl modes of the background, a network of ground-based interferometers is sensitive to both the gradient and curl components. The spatial separation of a network of interferometers, or of a single interferometer at different times during its rotational and orbital motion around the Sun, allows for recovery of both components. We derive expressions for the response functions …
Discovery And Follow-Up Of Rotating Radio Transients With The Green Bank And Lofar Telescopes, C. Karako-Argaman, V. M. Kaspi, R. S. Lynch, J. W.T. Hessels, V. I. Kondratiev, M. A. Mclaughlin, S. M. Ransom, A. M. Archibald, J. Boyles, F. A. Jenet, D. L. Kaplan, L. Levin, D. R. Lorimer, E. C. Madsen, M. S.E. Roberts, X. Siemens, I. H. Stairs, K. Stovall, J. K. Swiggum, J. Van Leeuwen
Discovery And Follow-Up Of Rotating Radio Transients With The Green Bank And Lofar Telescopes, C. Karako-Argaman, V. M. Kaspi, R. S. Lynch, J. W.T. Hessels, V. I. Kondratiev, M. A. Mclaughlin, S. M. Ransom, A. M. Archibald, J. Boyles, F. A. Jenet, D. L. Kaplan, L. Levin, D. R. Lorimer, E. C. Madsen, M. S.E. Roberts, X. Siemens, I. H. Stairs, K. Stovall, J. K. Swiggum, J. Van Leeuwen
Physics and Astronomy Faculty Publications and Presentations
We have discovered 21 Rotating Radio Transients (RRATs) in data from the Green Bank Telescope (GBT) 350 MHz Drift-scan and the Green Bank North Celestial Cap pulsar surveys using a new candidate sifting algorithm. RRATs are pulsars with sporadic emission that are detected through their bright single pulses rather than Fourier domain searches. We have developed RRATtrap, a single-pulse sifting algorithm that can be integrated into pulsar survey data analysis pipelines in order to find RRATs and Fast Radio Bursts. We have conducted follow-up observations of our newly discovered sources at several radio frequencies using the GBT and Low Frequency …
High Precision Optical Cavity Length And Width Measurements Using Double Modulation, A. Staley, D. Hoak, A. Effler, K. Izumi, S. Dwyer, K. Kawabe, E. J. King, Malik Rakhmanov, R. L. Savage, D. Sigg
High Precision Optical Cavity Length And Width Measurements Using Double Modulation, A. Staley, D. Hoak, A. Effler, K. Izumi, S. Dwyer, K. Kawabe, E. J. King, Malik Rakhmanov, R. L. Savage, D. Sigg
Physics and Astronomy Faculty Publications and Presentations
We use doubly phase modulated light to measure both the length and the linewidth of an optical resonator with high precision. The first modulation is at RF frequencies and is set near a multiple of the free spectral range, whereas the second modulation is at audio frequencies to eliminate offset errors at DC. The light in transmission or in reflection of the optical resonator is demodulated while sweeping the RF frequency over the optical resonance. We derive expressions for the demodulated power in transmission, and show that the zero crossings of the demodulated signal in transmission serve as a precise …
Measuring Infrared Surface Brightness Fluctuation Distances With Hst Wfc3: Calibration And Advice, Joseph B. Jensen, John P. Blakeslee, Zachary Gibson, Hyun Chul Lee, Michele Cantiello, Gabriella Raimondo, Nathan Boyer, Hyejeon Cho
Measuring Infrared Surface Brightness Fluctuation Distances With Hst Wfc3: Calibration And Advice, Joseph B. Jensen, John P. Blakeslee, Zachary Gibson, Hyun Chul Lee, Michele Cantiello, Gabriella Raimondo, Nathan Boyer, Hyejeon Cho
Physics and Astronomy Faculty Publications and Presentations
We present new calibrations of the near-infrared (near-IR) surface brightness fluctuation (SBF) distance method for the F110W (J110) and F160W (H160) bandpasses of the Wide Field Camera 3 Infrared Channel (WFC3/IR) on the Hubble Space Telescope. The calibrations are based on data for 16 early-type galaxies in the Virgo and Fornax clusters observed with WFC3/IR and are provided as functions of both the optical (g475-z850 ) and near-infrared (J110-H160) colors. The scatter about the linear calibration relations for the luminous red galaxies in the sample is approximately 0.10 mag, corresponding to a statistical error of 5% in distance. Our results …
High Precision Optical Cavity Length And Width Measurements Using Double Modulation, A. Staley, D. Hoak, A. Effler, K. Izumi, S. Dwyer, K. Kawabe, E. J. King, Malik Rakhmanov, R. L. Savage, D. Sigg
High Precision Optical Cavity Length And Width Measurements Using Double Modulation, A. Staley, D. Hoak, A. Effler, K. Izumi, S. Dwyer, K. Kawabe, E. J. King, Malik Rakhmanov, R. L. Savage, D. Sigg
Physics and Astronomy Faculty Publications and Presentations
We use doubly phase modulated light to measure both the length and the linewidth of an optical resonator with high precision. The first modulation is at RF frequencies and is set near a multiple of the free spectral range, whereas the second modulation is at audio frequencies to eliminate offset errors at DC. The light in transmission or in reflection of the optical resonator is demodulated while sweeping the RF frequency over the optical resonance. We derive expressions for the demodulated power in transmission, and show that the zero crossings of the demodulated signal in transmission serve as a precise …
Double Compact Objects. Iii. Gravitational-Wave Detection Rates, Michal Dominik, Emanuele Berti, Richard O'Shaughnessy, Ilya Mandel, Krzysztof Belczynski, Christopher Fryer, Daniel E. Holz, Tomasz Bulik, Francesco Pannarale
Double Compact Objects. Iii. Gravitational-Wave Detection Rates, Michal Dominik, Emanuele Berti, Richard O'Shaughnessy, Ilya Mandel, Krzysztof Belczynski, Christopher Fryer, Daniel E. Holz, Tomasz Bulik, Francesco Pannarale
Physics and Astronomy Faculty Publications and Presentations
The unprecedented range of second-generation gravitational-wave (GW) observatories calls for refining the predictions of potential sources and detection rates. The coalescence of double compact objects (DCOs)—i.e., neutron star–neutron star (NS–NS), black hole–neutron star (BH–NS), and black hole–black hole (BH–BH) binary systems—is the most promising source of GWs for these detectors. We compute detection rates of coalescing DCOs in second-generation GW detectors using the latest models for their cosmological evolution, and implementing inspiral-merger-ringdown gravitational waveform models in our signal-to-noise ratio calculations. We find that (1) the inclusion of the merger/ringdown portion of the signal does not significantly affect rates for NS–NS …
Einstein@Home Discovery Of A Palfa Millisecond Pulsar In An Eccentric Binary Orbit, B. Knispel, A. G. Lyne, B. W. Stappers, P. C.C. Freire, P. Lazarus, B. Allen, C. Aulbert, O. Bock, S. Bogdanov, A. Brazier, F. Camilo, F. Cardoso, S. Chatterjee, J. M. Cordes, F. Crawford, J. S. Deneva, H. B. Eggenstein, H. Fehrmann, R. Ferdman, J. W.T. Hessels, F. A. Jenet, C. Karako-Argaman, V. M. Kaspi, J. Van Leeuwen, D. R. Lorimer, R. Lynch, B. Machenschalk, E. Madsen, M. A. Mclaughlin, C. Patel
Einstein@Home Discovery Of A Palfa Millisecond Pulsar In An Eccentric Binary Orbit, B. Knispel, A. G. Lyne, B. W. Stappers, P. C.C. Freire, P. Lazarus, B. Allen, C. Aulbert, O. Bock, S. Bogdanov, A. Brazier, F. Camilo, F. Cardoso, S. Chatterjee, J. M. Cordes, F. Crawford, J. S. Deneva, H. B. Eggenstein, H. Fehrmann, R. Ferdman, J. W.T. Hessels, F. A. Jenet, C. Karako-Argaman, V. M. Kaspi, J. Van Leeuwen, D. R. Lorimer, R. Lynch, B. Machenschalk, E. Madsen, M. A. Mclaughlin, C. Patel
Physics and Astronomy Faculty Publications and Presentations
We report the discovery of the millisecond pulsar (MSP) PSR J1950+2414 (P = 4.3 ms) in a binary system with an eccentric (e = 0.08) 22 day orbit in Pulsar Arecibo L-band Feed Array survey observations with the Arecibo telescope. Its companion star has a median mass of 0.3 Mo and is most likely a white dwarf (WD). Fully recycled MSPs like this one are thought to be old neutron stars spun-up by mass transfer from a companion star. This process should circularize the orbit, as is observed for the vast majority of binary MSPs, which predominantly have orbital eccentricities …
Magnetism Of Fept Nanoclusters In Polyimide, Mircea Chipara, Tom George, Yingfan Xu, Ralph Skomski, Lanping Yue, Nasar Ali, David J. Sellmyer
Magnetism Of Fept Nanoclusters In Polyimide, Mircea Chipara, Tom George, Yingfan Xu, Ralph Skomski, Lanping Yue, Nasar Ali, David J. Sellmyer
Physics and Astronomy Faculty Publications and Presentations
FePt nanoclusters have been implanted onto polyimide films and subjected to thermal annealing in order to obtain a special magnetic phase (L10) dispersed within the polymer. SQUID measurements quantified the magnetic features of the as-prepared and annealed hybrid films. As-implanted FePt nanoparticles in polyimide films exhibited a blocking temperature of 70 ± 5 K. Thermal annealing in zero and 10 kOe applied magnetic field increased the magnetic anisotropy and coercivity of the samples. Wide Angle X-Ray Scattering confirmed the presence of FePt and L10 phase. All samples (as deposited and annealed) exhibited electron spin resonance spectra consisting of two overlapping …
Enzymatic Synthesis Of Magnetic Nanoparticles, Arati G. Kolhatkar, Chamath Dannongoda, Katerina Kourentzi, Andrew C. Jamison, Ivan Nekrashevich, Archana Kar, Eliedonna Cacao, Ulrich Strych, Irene Rusakova, Karen S. Martirosyan, Dmitri Litvinov, T. Randall Lee, Richard C. Willson
Enzymatic Synthesis Of Magnetic Nanoparticles, Arati G. Kolhatkar, Chamath Dannongoda, Katerina Kourentzi, Andrew C. Jamison, Ivan Nekrashevich, Archana Kar, Eliedonna Cacao, Ulrich Strych, Irene Rusakova, Karen S. Martirosyan, Dmitri Litvinov, T. Randall Lee, Richard C. Willson
Physics and Astronomy Faculty Publications and Presentations
We report the first in vitro enzymatic synthesis of paramagnetic and antiferromagnetic nanoparticles toward magnetic ELISA reporting. With our procedure, alkaline phosphatase catalyzes the dephosphorylation of L-ascorbic-2-phosphate, which then serves as a reducing agent for salts of iron, gadolinium, and holmium, forming magnetic precipitates of Fe45±14Gd5±2O50±15 and Fe42±4Ho6±4O52±5. The nanoparticles were found to be paramagnetic at 300 K and antiferromagnetic under 25 K. Although weakly magnetic at 300 K, the room-temperature magnetization of the nanoparticles found here is considerably greater than that of analogous chemically-synthesized LnxFeyOz (Ln = Gd, Ho) samples reported previously. At 5 K, the nanoparticles showed a …
Directed Search For Gravitational Waves From Scorpius X-1 With Initial Ligo Data, J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Ain, P. Ajith, A. Alemic, B. Allen, A. Allocca, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. S. Areeda, N. Arnaud
Directed Search For Gravitational Waves From Scorpius X-1 With Initial Ligo Data, J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Ain, P. Ajith, A. Alemic, B. Allen, A. Allocca, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. S. Areeda, N. Arnaud
Physics and Astronomy Faculty Publications and Presentations
We present results of a search for continuously emitted gravitational radiation, directed at the brightest low-mass x-ray binary, Scorpius X-1. Our semicoherent analysis covers 10 days of LIGO S5 data ranging from 50-550 Hz, and performs an incoherent sum of coherent F-statistic power distributed amongst frequency-modulated orbital sidebands. All candidates not removed at the veto stage were found to be consistent with noise at a 1% false alarm rate. We present Bayesian 95% confidence upper limits on gravitational-wave strain amplitude using two different prior distributions: a standard one, with no a priori assumptions about the orientation of Scorpius X-1; and …
Timing Of Five Millisecond Pulsars Discovered In The Palfa Survey, P. Scholz, V. M. Kaspi, A. G. Lyne, B. W. Stappers, S. Bogdanov, J. M. Cordes, F. Crawford, R. D. Ferdman, P. C.C. Freire, J. W.T. Hessels, D. R. Lorimer, I. H. Stairs, B. Allen, A. Brazier, F. Camilo, R. F. Cardoso, S. Chatterjee, J. S. Deneva, F. A. Jenet, C. Karako-Argaman, B. Knispel, P. Lazarus, K. J. Lee, J. Van Leeuwen, R. Lynch, E. C. Madsen, M. A. Mclaughlin, S. M. Ransom, X. Siemens, L. G. Spitler
Timing Of Five Millisecond Pulsars Discovered In The Palfa Survey, P. Scholz, V. M. Kaspi, A. G. Lyne, B. W. Stappers, S. Bogdanov, J. M. Cordes, F. Crawford, R. D. Ferdman, P. C.C. Freire, J. W.T. Hessels, D. R. Lorimer, I. H. Stairs, B. Allen, A. Brazier, F. Camilo, R. F. Cardoso, S. Chatterjee, J. S. Deneva, F. A. Jenet, C. Karako-Argaman, B. Knispel, P. Lazarus, K. J. Lee, J. Van Leeuwen, R. Lynch, E. C. Madsen, M. A. Mclaughlin, S. M. Ransom, X. Siemens, L. G. Spitler
Physics and Astronomy Faculty Publications and Presentations
We present the discovery of five millisecond pulsars (MSPs) from the PALFA Galactic plane survey using Arecibo. Four of these (PSRs J0557+1551, J1850+0244, J1902+0300, and J1943+2210) are binary pulsars whose companions are likely white dwarfs, and one (PSR J1905+0453) is isolated. Phase-coherent timing solutions, ranging from 1 to 3 yr in length, and based on observations from the Jodrell Bank and Arecibo telescopes, provide precise determinations of spin, orbital, and astrometric parameters. All five pulsars have large dispersion measures (>100 pc cm-3, within the top 20% of all known Galactic field MSPs) and are faint (1.4 GHz flux density …
Narrow-Band Search Of Continuous Gravitational-Wave Signals From Crab And Vela Pulsars In Virgo Vsr4 Data, J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Ain, P. Ajith, A. Alemic, B. Allen, A. Allocca, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. S. Areeda, Mario C. Diaz, Malik Rakhmanov, Joseph D. Romano, Soma Mukherjee, Volker Quetschke, Teviet Creighton, Robert Stone
Narrow-Band Search Of Continuous Gravitational-Wave Signals From Crab And Vela Pulsars In Virgo Vsr4 Data, J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Ain, P. Ajith, A. Alemic, B. Allen, A. Allocca, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. S. Areeda, Mario C. Diaz, Malik Rakhmanov, Joseph D. Romano, Soma Mukherjee, Volker Quetschke, Teviet Creighton, Robert Stone
Physics and Astronomy Faculty Publications and Presentations
In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational-wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95% confidence level upper limits have been computed assuming both that polarization parameters are completely unknown …
Searching For Stochastic Gravitational Waves Using Data From The Two Colocated Ligo Hanford Detectors, J. Aasi, J. Abadie, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T. Accadia, F. Acernese, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, C. Affeldt, M. Agathos, N. Aggarwal, O. D. Aguiar, P. Ajith, B. Allen, A. Allocca, E. Amador Ceron, D. Amariutei, R. A. Anderson, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. Areeda, S. Ast, S. M. Aston
Searching For Stochastic Gravitational Waves Using Data From The Two Colocated Ligo Hanford Detectors, J. Aasi, J. Abadie, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T. Accadia, F. Acernese, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, C. Affeldt, M. Agathos, N. Aggarwal, O. D. Aguiar, P. Ajith, B. Allen, A. Allocca, E. Amador Ceron, D. Amariutei, R. A. Anderson, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. Areeda, S. Ast, S. M. Aston
Physics and Astronomy Faculty Publications and Presentations
Searches for a stochastic gravitational-wave background (SGWB) using terrestrial detectors typically involve cross-correlating data from pairs of detectors. The sensitivity of such cross-correlation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a colocated detector pair is more sensitive to a gravitational-wave background than a noncolocated detector pair. However, colocated detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the …
Understanding The Gravitational-Wave Hellings And Downs Curve For Pulsar Timing Arrays In Terms Of Sound And Electromagnetic Waves, Fredrick A. Jenet, Joseph D. Romano
Understanding The Gravitational-Wave Hellings And Downs Curve For Pulsar Timing Arrays In Terms Of Sound And Electromagnetic Waves, Fredrick A. Jenet, Joseph D. Romano
Physics and Astronomy Faculty Publications and Presentations
Searches for stochastic gravitational-wave backgrounds using pulsar timing arrays look for correlations in the timing residuals induced by the background across the pulsars in the array. The correlation signature of an isotropic, unpolarized gravitational-wave background predicted by general relativity follows the so-called Hellings and Downs curve, which is a relatively simple function of the angle between a pair of Earth-pulsar baselines. In this paper, we give a pedagogical discussion of the Hellings and Downs curve for pulsar timing arrays, considering simpler analogous scenarios involving sound and electromagnetic waves. We calculate Hellings-and-Downs-type functions for these two scenarios and develop a framework …
Detection Of Temporal Changes In Vegetative Cover On South Padre Island, Texas Using Image Classifications Derived From Aerial Color-Infrared Photographs, Ruben A. Mazariegos, Kenneth R. Summy, Frank W. Judd, Robert I. Lonard, James H. Everitt
Detection Of Temporal Changes In Vegetative Cover On South Padre Island, Texas Using Image Classifications Derived From Aerial Color-Infrared Photographs, Ruben A. Mazariegos, Kenneth R. Summy, Frank W. Judd, Robert I. Lonard, James H. Everitt
Physics and Astronomy Faculty Publications and Presentations
Supervised image classifications developed from 23 x 23 cm aerial color-infrared aerial photographs (1:5,000 scale) were used to evaluate temporal changes in vegetative cover occurring within three 150 x 300-m research sites on South Padre Island, Texas. Use of high-resolution digitized imagery (ground pixel resolution of ca. 0.1 m) and survey-grade GPS for positional measurements of ground control points (20-25 1.0m2 targets within each research site) resulted in consistently high levels of geometric accuracy, with root mean square errors (RMSEs) ranging between 0.397 – 2.867. Similarly, use of relatively simple information categories (dry and wet sand, live and dead vegetative …
Prospects For Detection Of Extragalactic Stellar Black Hole Binaries In The Nearby Universe, Matthew Benacquista, Jesus Hinojosa, Alberto Mata, Krzysztof Belczynski
Prospects For Detection Of Extragalactic Stellar Black Hole Binaries In The Nearby Universe, Matthew Benacquista, Jesus Hinojosa, Alberto Mata, Krzysztof Belczynski
Physics and Astronomy Faculty Publications and Presentations
Stellar mass black hole binaries have individual masses between 10-80 solar masses. These systems may emit gravitational waves at frequencies detectable at Megaparsec distances by space-based gravitational wave observatories. In a previous study, we determined the selection effects of observing these systems with detectors similar to the Laser Interferometer Space Antenna by using a generated population of binary black holes that covered a reasonable parameter space and calculating their signal-to-noise ratio. We further our study by populating the galaxies in our nearby (less than 30 Mpc) universe with binary black hole systems drawn from a distribution found in the Synthetic …
Analogs Of Ldl Receptor Ligand Motifs In Dengue Envelope And Capsid Proteins As Potential Codes For Cell Entry, Juan Guevara Jr., Jamie Romo Jr., Troy Mcwhorter, Natalia Valentinova Guevara
Analogs Of Ldl Receptor Ligand Motifs In Dengue Envelope And Capsid Proteins As Potential Codes For Cell Entry, Juan Guevara Jr., Jamie Romo Jr., Troy Mcwhorter, Natalia Valentinova Guevara
Physics and Astronomy Faculty Publications and Presentations
It is established that cell entry of low density lipoprotein particles (LLPs) containing Apo B100 and Apo E is mediated by receptors and GAGs. Receptor ligand motifs, XBBBXXBX, XBBXBX, and ΨBΨXB, and mono- and bipartite NLS sequences are abundant in Apo E and Apo B100 as well as in envelope and capsid proteins of Dengue viruses 1-4 (DENV1-4). Synthetic, fluorescence-labeled peptides of sequences in DENV2 envelope protein, and DENV3 capsid that include these motifs were used to conduct a qualitative assessment of cell binding and entry capacity using …