Physical Sciences and Mathematics Commons^™

Sensitivity Curves For Searches For Gravitational-Wave Backgrounds, E. H. Thrane, Joseph D. Romano

Physics and Astronomy Faculty Publications and Presentations

We propose a graphical representation of detector sensitivity curves for stochastic gravitational-wave backgrounds that takes into account the increase in sensitivity that comes from integrating over frequency in addition to integrating over time. This method is valid for backgrounds that have a power-law spectrum in the analysis band. We call these graphs “power-law integrated curves.” For simplicity, we consider cross-correlation searches for unpolarized and isotropic stochastic backgrounds using two or more detectors. We apply our method to construct power-law integrated sensitivity curves for second-generation ground-based detectors such as Advanced LIGO, space-based detectors such as LISA and the Big Bang Observer, …

Detection Of Pulsar Beams Deflected By The Black Hole In Sgr A*: Effects Of Black Hole Spin, Sourabh Nampalliwar, Richard H. Price, Teviet Creighton, Fredrick A. Jenet

Physics and Astronomy Faculty Publications and Presentations

Some Galactic models predict a significant population of radio pulsars close to the Galactic center. Beams from these pulsars could be strongly deflected by the supermassive black hole (SMBH) believed to reside at the Galactic center and as a result reach Earth. Earlier work assuming a Schwarzschild SMBH gave marginal chances of observing this exotic phenomenon with current telescopes and good chances with future telescopes. Here we study whether those estimates are significantly affected by SMBH spin. We find that spin effects make a negligible difference in detectability, but the pattern of pulse arrival times is clearly affected. In particular, …

An Integrated Multidisciplinary Nanoscience Concentration Certificate Program For Stem Education, Karen S. Martirosyan, Mikhail M. Bouniaev, Malik Rakhmanov, Ahmed Touhami, Nazmul Islam, Davood Askari, Tarek Trad, Dmitri Litvinov, Sergey E. Lyshevski

Physics and Astronomy Faculty Publications and Presentations

Integration of nanoscience and nanotechnology curricula into the College of Science, Mathematics, and Technology (CSMT) at the University of Texas at Brownsville (UTB) is reported. The rationale for the established multidisciplinary Nanoscience Concentration Certificate Program (NCCP) is to: (i) develop nanotechnology-relevant courses within a comprehensive Science, Engineering and Technology curriculum, and, to offer students an opportunity to graduate with a certificate in nanoscience and nanotechnology; (ii) to contribute to students' success in achieving student outcomes across all college's majors, and, improve the breath, depth and quality of science, technology, engineering and mathematics (STEM) graduates' education; (iii) through NCCP, recruit certificate- …

Directed Search For Continuous Gravitational Waves From The Galactic Center, J. Aasi, Daniel Bessis, Teviet Creighton, H. Daveloza, Mario C. Diaz, S. R. Morriss, Soma Mukherjee, W. Ortega Larcher, M. E. Normandin, Volker Quetschke, O. Puncken, Malik Rakhmanov, Joseph D. Romano, Robert Stone, A. S. Stroeer, Lappoon R. Tang, Cristina V. Torres, D. Vrinceanu

Physics and Astronomy Faculty Publications and Presentations

We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic center region, performed on two years of data from LIGO’s fifth science run from two LIGO detectors. The search uses a semicoherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of first-order spindown values down to −7.86×10−8  Hz/s at the highest frequency. No gravitational waves were detected. The 90% confidence upper limits …

The Stochastic Background: Scaling Laws And Time To Detection For Pulsar Timing Arrays, X. Siemens, Justin A. Ellis, Fredrick A. Jenet, Joseph D. Romano

Physics and Astronomy Faculty Publications and Presentations

We derive scaling laws for the signal-to-noise ratio of the optimal cross-correlation statistic, and show that the large power-law increase of the signal-to-noise ratio as a function of the observation time T that is usually assumed holds only at early times. After enough time has elapsed, pulsar timing arrays enter a new regime where the signal to noise only scales as . In addition, in this regime the quality of the pulsar timing data and the cadence become relatively unimportant. This occurs because the lowest frequencies of the pulsar timing residuals become gravitational-wave dominated. Pulsar timing arrays enter this regime …

Searching For Millisecond Pulsars: Surveys, Techniques And Prospects, Kevin Stovall, Duncan R. Lorimer, R. S. Lynch

Physics and Astronomy Faculty Publications and Presentations

Searches for millisecond pulsars (which we here loosely define as those with periods < 20 ms) in the galactic field have undergone a renaissance in the past five years. New or recently refurbished radio telescopes utilizing cooled receivers and state-of-the art digital data acquisition systems are carrying out surveys of the entire sky at a variety of radio frequencies. Targeted searches for millisecond pulsars in point sources identified by the Fermi Gamma-ray Space Telescope have proved phenomenally successful, with over 50 discoveries in the past five years. The current sample of millisecond pulsars now numbers almost 200 and, for the first time in 25 years, now outnumbers their counterparts in galactic globular clusters. While many of these searches are motivated to find pulsars which form part of pulsar timing arrays, a wide variety of interesting systems are now being found. Following a brief overview of the millisecond pulsar phenomenon, we describe these searches and present some of …

Goals Strategies And First Discoveries Of Ao327 The Arecibo All-Sky 327 Mhz Drift Pulsar Survey, J. S. Deneva, K. Stovall, M. A. Mclaughlin, S. D. Bates, P. C.C. Freire, J. G. Martinez, F. Jenet, M. Bagchi

Physics and Astronomy Faculty Publications and Presentations

We report initial results from AO327, a drift survey for pulsars with the Arecibo telescope at 327 MHz. The first phase of AO327 will cover the sky at declinations of -1° to 28°, excluding the region within 5° of the Galactic plane, where high scattering and dispersion make low-frequency surveys sub-optimal. We record data from a 57 MHz bandwidth with 1024 channels and 125 μs sampling time. The 60 s transit time through the AO327 beam means that the survey is sensitive to very tight relativistic binaries even with no acceleration searches. To date we have detected 44 known pulsars …

The Einstein@Home Search For Radio Pulsars And Psr J2007+2722 Discovery, B. Allen, B. Knispel, J. M. Cordes, J. S. Deneva, J. W.T. Hessels, D. Anderson, C. Aulbert, O. Bock, A. Brazier, S. Chatterjee, P. B. Demorest, H. B. Eggenstein, H. Fehrmann, E. V. Gotthelf, D. Hammer, V. M. Kaspi, M. Kramer, A. G. Lyne, B. Machenschalk, M. A. Mclaughlin, C. Messenger, H. J. Pletsch, S. M. Ransom, I. H. Stairs, B. W. Stappers, N. D.R. Bhat, S. Bogdanov, F. Camilo, D. J. Champion, F. Crawford

Physics and Astronomy Faculty Publications and Presentations

Einstein@Home aggregates the computer power of hundreds of thousands of volunteers from 193 countries, to search for new neutron stars using data from electromagnetic and gravitational-wave detectors. This paper presents a detailed description of the search for new radio pulsars using Pulsar ALFA survey data from the Arecibo Observatory. The enormous computing power allows this search to cover a new region of parameter space; it can detect pulsars in binary systems with orbital periods as short as 11 minutes. We also describe the first Einstein@Home discovery, the 40.8 Hz isolated pulsar PSR J2007+2722, and provide a full timing model. PSR …

Timing And Interstellar Scattering Of 35 Distant Pulsars Discovered In The Palfa Survey, D. J. Nice, E. Altiere, S. Bogdanov, J. M. Cordes, D. Farrington, J. W.T. Hessels, V. M. Kaspi, A. G. Lyne, L. Popa, S. M. Ransom, S. Sanpa-Arsa, B. W. Stappers, Y. Wang, B. Allen, N. D.R. Bhat, A. Brazier, F. Camilo, D. J. Champion, S. Chatterjee, F. Crawford, J. S. Deneva, G. Desvignes, P. C.C. Freire, F. A. Jenet, B. Knispel, P. Lazarus, K. J. Lee, J. Van Leeuwen, D. R. Lorimer, R. Lynch

Physics and Astronomy Faculty Publications and Presentations

We have made extensive observations of 35 distant slow (non-recycled) pulsars discovered in the ongoing Arecibo PALFA pulsar survey. Timing observations of these pulsars over several years at Arecibo Observatory and Jodrell Bank Observatory have yielded high-precision positions and measurements of rotation properties. Despite being a relatively distant population, these pulsars have properties that mirror those of the previously known pulsar population. Many of the sources exhibit timing noise, and one underwent a small glitch. We have used multifrequency data to measure the interstellar scattering properties of these pulsars. We find scattering to be higher than predicted along some lines …

Peace: Pulsar Evaluation Algorithm For Candidate Extraction-A Software Package For Post-Analysis Processing Of Pulsar Survey Candidates, K. J. Lee, K. Stovall, F. A. Jenet, J. Martinez, L. P. Dartez, A. Mata, G. Lunsford, S. Cohen, C. M. Biwer, M. Rohr, J. Flanigan, A. Walker, S. Banaszak, B. Allen, E. D. Barr, N. D.R. Bhat, S. Bogdanov, A. Brazier, F. Camilo, D. J. Champion, S. Chatterjee, J. Cordes, F. Crawford, J. Deneva, G. Desvignes, R. D. Ferdman, P. Freire, J. W.T. Hessels, R. Karuppusamy, V. M. Kaspi

Physics and Astronomy Faculty Publications and Presentations

Modern radio pulsar surveys produce a large volume of prospective candidates, the majorityof which are polluted by human-created radio frequency interference or other forms of noise. Typically, large numbers of candidates need to be visually inspected in order to determineif they are real pulsars. This process can be labour intensive. In this paper, we introducean algorithm called Pulsar Evaluation Algorithm for Candidate Extraction (PEACE) whichimproves the efficiency of identifying pulsar signals. The algorithm ranks the candidates basedon a score function. Unlike popular machine-learning-based algorithms, no prior training datasets are required. This algorithm has been applied to data from several large-scale …

Observation Of Asymmetric Transport In Structures With Active Nonlinearities, N. Bender, S. Factor, J. D. Bodyfelt, Hamidreza Ramezani, D. N. Christodoulides, F. M. Ellis, T. Kottos

Physics and Astronomy Faculty Publications and Presentations

A mechanism for asymmetric transport which is based on parity-time- symmetric nonlinearities is presented. We show that in contrast to the case of conservative nonlinearities, an increase of the complementary conductance strength leads to a simultaneous increase of asymmetry and transmittance intensity. We experimentally demonstrate the phenomenon using a pair of coupled Van der Pol oscillators as a reference system, each with complementary anharmonic gain and loss conductances, connected to transmission lines. An equivalent optical setup is also proposed. © 2013 American Physical Society.

The Thermodynamics Of Dna Loop Formation, From J To Z, Stephen D. Levene, Stefan M. Giovan, Andreas Hanke, Massa J. Shoura

Physics and Astronomy Faculty Publications and Presentations

The formation of DNA loops is a ubiquitous theme in biological processes, including DNA replication, recombination and repair, and gene regulation. These loops are mediated by proteins bound at specific sites along the contour of a single DNA molecule, in some cases many thousands of base pairs apart. Loop formation incurs a thermodynamic cost that is a sensitive function of the length of looped DNA as well as the geometry and elastic properties of the DNA-bound protein. The free energy of DNA looping is logarithmically related to a generalization of the Jacobson-Stockmayer factor for DNA cyclization, termed the J factor. …

A Biodistribution And Toxicity Study Of Cobalt Dichloride–Nacetyl Cysteine (C4) As An Implantable Mri Marker For Prostate Cancer Treatment, Steven J. Frank, Mary J. Johansen, Karen S. Martirosyan, Mihai Gagea, Carolyn S. Van Pelt

Physics and Astronomy Faculty Publications and Presentations

Purpose—C4, a cobalt dichloride–N-acetyl cysteine complex, is being developed as a positivesignal magnetic resonance imaging (MRI) marker to localize implanted radioactive seeds in prostate brachytherapy. We evaluated the toxicity and biodistribution of C4 in rats with the goal of simulating systemic effects of potential leakage from C4 MRI markers within the prostate.

Methods—9 μl doses (equivalent to leakage from 120 markers in a human) of control (0.9% sodium chloride), 1% (proposed for clinical use) and 10% C4 solution were injected into the prostates of male Sprague-Dawley rats via laparotomy. Organ toxicity and cobalt disposition in plasma, tissues, feces …

Einstein@Home All-Sky Search For Periodic Gravitational Waves In Ligo S5 Data, J. Aasi, J. Abadie, B. P. Abbott, R. Abbott, T. D. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, T. Adams, P. Addesso, R. Adhikari, C. Affeldt, M. Agathos, K. Agatsuma, P. Ajith, B. Allen, A. Allocca, E. Amador Ceron, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, S. Ast, S. M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C. Aulbert

Physics and Astronomy Faculty Publications and Presentations

This paper presents results of an all-sky search for periodic gravitational waves in the frequency range [50,1 190] Hz and with frequency derivative range of ∼[-20,1.1]×10-10 Hz s-1 for the fifth LIGO science run (S5). The search uses a noncoherent Hough-transform method to combine the information from coherent searches on time scales of about one day. Because these searches are very computationally intensive, they have been carried out with the Einstein@Home volunteer distributed computing project. Postprocessing identifies eight candidate signals; deeper follow-up studies rule them out. Hence, since no gravitational wave signals have been found, we report upper limits on …

Search For Gravitational Waves From Binary Black Hole Inspiral Merger And Ringdown In Ligo-Virgo Data From 2009-2010, J. Aasi, J. Abadie, B. P. Abbott, R. Abbott, T. D. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, T. Adams, P. Addesso, R. Adhikari, C. Affeldt, M. Agathos, K. Agatsuma, P. Ajith, B. Allen, A. Allocca, E. Amador Ceron, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, S. Ast, S. M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C. Aulbert

Physics and Astronomy Faculty Publications and Presentations

We report a search for gravitational waves from the inspiral, merger and ringdown of binary black holes (BBH) with total mass between 25 and 100 solar masses, in data taken at the LIGO and Virgo observatories between July 7, 2009 and October 20, 2010. The maximum sensitive distance of the detectors over this period for a (20,20)M⊙ coalescence was 300 Mpc. No gravitational wave signals were found. We thus report upper limits on the astrophysical coalescence rates of BBH as a function of the component masses for nonspinning components, and also evaluate the dependence of the search sensitivity on …

Non-Equilibrium Casimir Force Between Vibrating Plates, Andreas Hanke

Physics and Astronomy Faculty Publications and Presentations

We study the fluctuation-induced, time-dependent force between two plates confining a correlated fluid which is driven out of equilibrium mechanically by harmonic vibrations of one of the plates. For a purely relaxational dynamics of the fluid we calculate the fluctuation-induced force generated by the vibrating plate on the plate at rest. The time-dependence of this force is characterized by a positive lag time with respect to the driving. We obtain two distinctive contributions to the force, one generated by diffusion of stress in the fluid and another related to resonant dissipation in the cavity. The relation to the dynamic Casimir …

Limits On The Stochastic Gravitational Wave Background From The North American Nanohertz Observatory For Gravitational Waves, P. B. Demorest, R. D. Ferdman, M. E. Gonzalez, D. Nice, S. Ransom, I. H. Stairs, Z. Arzoumanian, A. Brazier, S. Burke-Spolaor, S. J. Chamberlin, J. M. Cordes, J. Ellis, L. S. Finn, P. Freire, S. Giampanis, F. Jenet, V. M. Kaspi, J. Lazio, A. N. Lommen, M. Mclaughlin, N. Palliyaguru, D. Perrodin, R. M. Shannon, X. Siemens, D. Stinebring, J. Swiggum, W. W. Zhu

Physics and Astronomy Faculty Publications and Presentations

We present an analysis of high-precision pulsar timing data taken as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We have observed 17 pulsars for a span of roughly five years using the Green Bank and Arecibo radio telescopes. We analyze these data using standard pulsar timing models, with the addition of time-variable dispersion measure and frequency-variable pulse shape terms. Sub-microsecond timing residuals are obtained in nearly all cases, and the best rms timing residuals in this set are &thk30-50 ns. We present methods for analyzing post-fit timing residuals for the presence of a gravitational wave …

Carbon Monoxide Adsorption On Platinum-Osmium And Platinum-Ruthenium-Osmium Mixed Nanoparticles, N. Dimakis, Nestor E. Navarro, Eugene S. Smotkin

Physics and Astronomy Faculty Publications and Presentations

Density functional calculations (DFT) on carbon monoxide (CO) adsorbed on platinum, platinum-osmium, and platinum-ruthenium-osmium nanoclusters are used to elucidate changes on the adsorbate internal bond and the carbon-metal bond, as platinum is alloyed with osmium and ruthenium atoms. The relative strengths of the adsorbate internal bond and the carbon-metal bond upon alloying, which are related to the DFT calculated C–O and C–Pt stretching frequencies, respectively, cannot be explained by the traditional 5σ-donation/2π*-back-donation theoretical model. Using a modified π-attraction σ-repulsion mechanism, we ascribe the strength of the CO adsorbate internal bond to changes in the polarization of the adsorbate-substrate hybrid orbitals …

Study Of Dynamic Features Of Highly Energetic Reactions By Dsc And High-Speed Temperature Scanner (Hsts), Mkhitar Hobosyan, Kh. G. Kirakosyan, S. L. Kharatyan, Karen S. Martirosyan

Physics and Astronomy Faculty Publications and Presentations

The dynamic features of Al2O3 - polytetrafluoroethylene (PTFE) and Al - PTFE reactions in non-isothermal conditions are presented. The Differential Scanning Calorimetry (DSC) and High-Speed Temperature Scanner (HSTS) were used to characterize the Al2O3/Al – PTFE reactions at different heating rates. The study shows that the HSTS instrument can give more information about the reaction mechanism and kinetics than the conventional DSC measurements. In this work we show that high heating rates may reveal exothermic reaction between Al2O3 and PTFE that were previously unidentified. The PTFE can potentially remove the oxide layer from aluminum in the initial period of the …

Search For Long-Lived Gravitational-Wave Transients Coincident With Long Gamma-Ray Bursts, J. Aasi, Daniel Bessis, Teviet Creighton, H. Daveloza, Mario C. Diaz, S. R. Morriss, Soma Mukherjee, M. E. Normandin, W. Ortega Larcher, O. Puncken, Malik Rakhmanov, Volker Quetschke, Joseph D. Romano, A. S. Stroeer, Robert Stone, Lappoon R. Tang, Cristina V. Torres

Physics and Astronomy Faculty Publications and Presentations

Long gamma-ray bursts (GRBs) have been linked to extreme core-collapse supernovae from massive stars. Gravitational waves (GW) offer a probe of the physics behind long GRBs. We investigate models of long-lived (~10–1000 s) GW emission associated with the accretion disk of a collapsed star or with its protoneutron star remnant. Using data from LIGO’s fifth science run, and GRB triggers from the Swift experiment, we perform a search for unmodeled long-lived GW transients. Finding no evidence of GW emission, we place 90% confidence-level upper limits on the GW fluence at Earth from long GRBs for three waveforms inspired by a …

Parameter Estimation For Compact Binary Coalescence Signals With The First Generation Gravitational-Wave Detector Network, J. Aasi, J. Abadie, Matthew Benacquista, R. Biswas, G. Cagnoli, Teviet Creighton, H. Daveloza, Mario C. Diaz, S. R. Morriss, Soma Mukherjee, M. E. Normandin, Volker Quetschke, Malik Rakhmanov, Robert Stone, A. S. Stroeer, Cristina V. Torres

Physics and Astronomy Faculty Publications and Presentations

Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and …