Bulletin of the American Physical Society
2018 Annual Meeting of the Far West Section
Volume 63, Number 17
Thursday–Saturday, October 18–20, 2018; Cal State Fullerton, Fullerton, California
Session B03: Gravitation 
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Chair: Geoffrey Lovelace, California State University, Fullerton Room: Titan Student Union Alverado AB 
Friday, October 19, 2018 2:00PM  2:12PM 
B03.00001: Derivation of Cosmic Acceleration Given Anisotropic Lightspeed in the Hubble Expansion Thomas E Chamberlain The Baryonic TullyFisher Relation shows farfield gravitation around spiral galaxies declining as 1/r while Type Ia supernovas point to cosmic acceleration, both phenomena unexplained by general relativity (GR). However, when Einstein's isotropic lightspeed is succeeded by more fundamental anisotropic lightspeed – specifically, unbounded inward with c/2 outward – within Hubble spaceexpansion a cosmic time dilation emerges for explaining (pure) cosmic acceleration, a_{CA} = rH ^{2}. Net cosmic acceleration – i.e., pure cosmic acceleration counteracted by (baryonic) GR and subfield cosmic decelerations – is in accord with SNIa luminositymagnitude (median) residuals in the 0.01 ≤ z ≤ 0.3 redshift range, where the significant complications at greater redshifts are postponed. Uniting cosmic timedilation with Schwarzschildsolution time dilation allows modeling of 1/r farfield gravitation around galaxies giving a relativistic formulation of Milgrom's Deep MOND. Both advances exhibit the empirical acceleration scale 1.2E10 m/s^2 and are in accord with Einstein’s gravitational effects near the Sun. Combining subfield gravity and Schwarzschild gravity gives crossover of the two components at near 7,000 AU from the Sun, in agreement with wide binary star rotation measurements. 
Friday, October 19, 2018 2:12PM  2:24PM 
B03.00002: A New Multimode Apparatus to Determine G C.D. Hoyle, Ricardo Decca, Stefan Ballmer Of all the fundamental constants in nature, G, the Newtonian gravitational constant, is known with the least precision. The world's best experiments yield values which are incompatible with one another and differ by about 50 times the uncertainty of the most precise experiment. Two recent experiments have, however, obtained consistent results at the 12 ppm level. Since it is possible that a portion of the past discrepancies between determinations of G can be traced back to the methodology used, the research group at IUPUI, in collaboration with Humboldt State University and Syracuse University, will combine different approaches to determine G within the same torsion pendulum apparatus. We expect to obtain a measurement of G at the 2 ppm level from each method. With the experiments carried out in the same apparatus, the effort will also help to understand the current discrepancies among existing experimental results. This talk will explore the experimental configurations as well as give a general status update on this relatively new project. 
Friday, October 19, 2018 2:24PM  2:36PM 
B03.00003: Inferring the binary black hole population redshift distribution Denyz Melchor In the past years LIGOVIRGO has detected five binary black hole mergers; in the universe, there are one hundred thousand binary black hole mergers a year which creates motivation to investigate populations of black holes. New searches are currently being designed to detect the signature of the gravitational wave background of all the distant binary black hole mergers. I will describe the process of how we apply statistical inference to describe the astrophysical parameters of this background. My focus will be in inferring the redshift distribution of the population of black holes which has implications in star formation and primordial black holes. 
Friday, October 19, 2018 2:36PM  2:48PM 
B03.00004: New StickSlip Tests of the Mach Effect Gravitational Assist (MEGA) Drive Heidi Fearn, James F Woodward, Jose J. A. Rodal The MEGA drive is an innovative design for an electric propellant–less propulsion system. The drive consists of a lead zironate titanate transducer compressed between an aluminum mass and a larger brass reaction mass. The gravitational mechanism for force production is described in Woodward [1]. Force measurements are performed using a torsional balance, where a beam displacement is used to calculate the force. In this paper we wish to present new results, where we have eliminated any stick–slip effect present in the thread and screws which could be responsible for giving a false positive force result for the drive. It is possible that stick–slip, in the mixed lubrication regime, may be present in the 12 screws, holding the PZT stack to the brass reaction mass and securing the brass to the L bracket. The procedure will be as follows: (1) Run one MEGA device to get standard data for comparison. 
Friday, October 19, 2018 2:48PM  3:00PM 
B03.00005: Progress on Shortrange Tests of Gravity at Humboldt State University Kassandra A. Weber, Charles D Hoyle, Nicholas Hernandez, Jackson Stillman Due to discrepancies between the Standard Model and General Relativity, gravitational experiments have remained at the forefront of experimental physics research in an effort to unify these models. Theories which attempt this unification often include features that violate the Weak Equivalence Principle (WEP) and/or the gravitational InverseSquare Law (ISL), potentially bringing our fundamental understanding of gravity into question.Therefore, students and faculty and Humboldt State have constructed an apparatus that will measure the effects of gravity at a submillimeter scale. This experiment measures the twist of a torsion pendulum as an attractor mass is oscillated nearby, providing a timevarying torque on the pendulum. In the experiment, the size and distance dependence of the torque are measured, thereby providing means to determine deviations from accepted models of gravity on untested distance scales. As with all gravitational experiments, characterization of systematic effects due to environmental fluctuations is paramount. This talk will focus on the development of a system to assess the impact of temperature variations on the apparatus and give a general status update on this work. 
Friday, October 19, 2018 3:00PM  3:12PM 
B03.00006: Production and potential detection of electromagnetic radiation from gravitational waves Douglas Alexander Singleton, Preston Jones, Andri Gretarsson This talk presents the possibility of observing very low frequency (VLF) electromagnetic radiation produced from the vacuum by gravitational waves. We give a brief review of the calculations leading to the possibility of vacuum conversion of gravitational waves into electromagnetic waves and we show how this process evades the wellknown prohibition against particle production from gravitational waves. Using NewmanPenrose scalars, we estimate the luminosity of this proposed electromagnetic counterpart radiation coming from gravitational waves produced by neutron star oscillations. The detection of electromagnetic counterpart radiation would provide an indirect way of observing gravitational radiation with future spacecraft missions, especially lunar orbiting probes. 
Friday, October 19, 2018 3:12PM  3:24PM 
B03.00007: Identifying Correlations Between LIGO's Astronomical Range and Auxiliary Sensors Using Lasso Regression Jeffrey Bidler The range to which the Laser Interferometer GravitationalWave Observatory (LIGO) can observe astrophysical systems varies over time, limited by noise in the instruments and their environments. Identifying and removing the sources of noise that limit LIGO's range enables higher signaltonoise observations and increases the number of observations. The LIGO observatories are continuously monitored by hundreds of thousands of auxiliary channels that may contain information about these noise sources. This paper describes an algorithm that uses linear regression, namely lasso (least absolute shrinkage and selection operator) regression, to analyze all of these channels and identify a small subset of them that can be used to reconstruct variations in LIGO's astrophysical range. Exemplary results of the application of this method to three different periods of LIGO Livingston data are presented, along with computational performance and current limitations. 
Friday, October 19, 2018 3:24PM  3:36PM 
B03.00008: Hybrid Gravitational Wave Systematics and Model Comparisons Eric Flynn The detectability and measurement of any gravitational wave source is dependent on models of the inspiral, merger, and post merger of a binary system. Numerical simulations as well as analytic models are widely used within the LIGO collaboration to recover gravitational wave signals and source parameters. However, numerical simulations of the inspiral, merger, and post merger are computationally expensive which limits the duration of the of the simulated signal. On the other hand, analytic models are computationally inexpensive but do not always accurately model the merger or post merger. Hybrid gravitational waves join analytical and numerical pieces to make a single model. Their accuracy depends on a set of construction parameters, and can contribute to systematic error when using hybrid models. We identify and study the effect construction parameters have on hybrid waveforms modeling binary neutron star mergers used for waveform detection and parameter estimation to leading order. By marginalizing over these sources of error for nonspinning, nonequal mass binaries from Computational Relativity (CoRe) library, we show a family of hybrid waveforms can be constructed within accuracy bounds needed by the LIGO detectors. 
Friday, October 19, 2018 3:36PM  3:48PM 
B03.00009: Improving the Cooldown times for Third Generation Gravitational Wave Observatories Edgard L Bonilla Carrasquel, Jaimi Salone, Brian T Lantz Interferometric gravitational wave observatories recently launched a new field of gravitational wave astronomy with the first detections of gravitational waves in 2015. The number and quality of these detections is limited in part by thermally induced vibrations in the mirrors, which show up as noise in these interferometers. One way to reduce this thermally induced noise is to use low temperature mirrors made of high purity singlecrystalline silicon. Although the operating temperature can be reached without compromising the isolation of the optic components by using a dual shield system and radiative cooling, the cooldown times are slow and unpractical for a full scale mirror like the ones planned for the next iteration of LIGO, LIGO Voyager. We experimentally demonstrate the cooldown time can be improved by injecting gaseous Nitrogen in the two shield array. It is also shown that this procedure does not compromise the temperature of the rest of the apparatus inside the vacuum chamber. Finally these results can be reliably scaled up to satisfy the requirements imposed by a future LIGO Voyager design.

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