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 E03: Poster Session 3 |
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Chair: Joshua Smith, California State University, Fullerton Room: Titan Student Union Pavillion A |
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E03.00001: The Crust Equation of State for Neutron Stars Amauri Tapia, Jocelyn Samantha Read The Laser Interferometer Gravitational Wave Observatory (LIGO) measures gravitational waves from black holes and neutron stars. Gravitational waves from neutron star mergers can be further used to study neutron star populations, properties of neutron stars and dense matter. One of the current challenges is to accurately model the equation of state which describes the state of matter in neutron stars. The LIGO Scientific Collaboration Algorithm Library (LAL) currently includes tabled equations of state for neutron stars designed to model a range of behavior in the core of the star. Currently, the library does not include realistic representations of how the neutron-star crust behaves over the possible range of nuclear interactions. I am working to incorporate realistic neutron star crust equations of state into LAL. This poster will highlight the current state of the project including matched EOSs between the core and crust in addition to its implications for the mass-radius relationship of neutron stars. |
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E03.00002: Magnetic Loops on the Sun Cindy Perez, Nicholas James Nelson, Austin R Pollard, Jose L Baranda Magnetic spots on Sun like stars are a major driver of space weather and can impact habitability of planets. Sunspots are formed in the interior of the Sun starting in the convection zone where the differential rotation creates pressure causing the loops to become buoyant enough to rise to the photosphere. The formation of sunspots progenitors has been modeled using 3D magnetohydrodynamic simulation of stellar convection. These buoyant magnetic loops are small coherent structures in a large turbulent volume, therefore making the loops hard to find. Here we report on a project to develop and empower post-processing tools for there simulated data sets. We have located almost 200 loops between $0.90 R_{\odot}$ to $0.98R_{\odot}$ and have begun to track their motion through the convection zone. |
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E03.00003: Dynamical Chaos in Stellar Evolution Models Forrest JA Bullard, Nicholas James Nelson Stellar evolution models are a ubiquitous tool in astrophysics for understanding stars individually and in groups, with applications from exoplanet characterization to galaxy formation. These models solve a system of highly nonlinear intergo-differential equations and have a very high dimensional effective phase space, thus they have the potential to exhibit dynamical chaos. Using the open source MESA (Modules for Experiments in Stellar Evolution) code to conduct our simulations, we simulate a variety of stars around one solar mass with differing values of initial surface rotational velocity. Each model is compared against an otherwise identical model whose initial conditions differ by one part in $10^8$. We compute the distance between the two nearly-identical models in a phase space of density, temperature, and hydrogen fraction as functions of radius, which allows us to compute the maximum Lyapunov exponent. This determines the rate of exponential divergence or convergence of trajectories through phase space. We present initial results that demonstrate that a solar-like stellar evolution model yields dynamical chaos with a Lyapunov time of about $10^8$ years. |
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E03.00004: Mountaintop Neutrino Detection: A New Concept for the Radio Detection of the Highest Energy Tau Neutrinos Mercedes Megan Vasquez Neutrinos produced by the propagation of ultra-high energy cosmic rays outside our galaxy carry with them information about their sources. As a tau neutrino propagates through the Earth it may undergo a charged-current interaction leading to the production of a tau lepton. A tau lepton exiting the Earth’s surface will decay creating an upwardly propagating air shower. BEACON, Beamforming Elevated Array for COsmic Neutrinos, will use a high-altitude antenna array sensitive to these air showers to search for high-energy (E>100 PeV) tau neutrinos. Our group traveled to White Mountain Research Station (WMRS) to attempt to demonstrate that the radio background at a potential site is low enough for a high-altitude detector to distinguish a neutrino signal. We measured the local radio background using a custom-designed broadband transient detector and installed an array of 30-80 MHz antennas with custom electronics that use coherent phasing on a field-programmable gate array (FPGA). The instrument will run for the next year as a testbed where we can implement strategies in firmware to reduce trigger rates from the local radio environment. In this poster I will characterize the broadband (30-1000MHz) radio background at WMRS and discuss its potential as a more permanent site for BEACON. |
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E03.00005: Reconstructing the Merger History of the Milky Way Using Gaia Austin R Pollard The current model for galaxy formation, Λ-CDM, predicts that galaxies are built from the accumulation and disruption of other small galaxies. Such merger events are expected to leave imprints on the kinematics of the affected stars. Due to this, the hypothesis proposed by this model can be tested in the Milky Way by studying the dynamics of individual stars for which full phase information is available – three-dimensional positions and velocities. Previous observational surveys have only been able to retrieve this for a small fraction of stars in the solar neighborhood, severely limiting the conclusions that can be drawn. However, with the recent second data release (DR2) of the Gaia Archive, observational data from millions of stars has been made available, allowing more thorough comparisons between the observations and galaxy formation models. This project involved the acquisition and analysis of recent data sets from Gaia DR2, and sought to identify structures present in phase space that are debris from previous merging events in our galaxy. Such identified structures can be cross-correlated with well known surviving objects, such as the globular cluster ωCen, which has long been hypothesized to be the core of a dwarf galaxy that was disrupted by the Milky Way tidal field. |
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E03.00006: Visualizing Binary Black Hole Collisions and Gravitational Waves Teresita Ramirez, Geoffrey Lovelace Gravitational waves are ripples in the fabric of space and time, traveling at the speed of light predicted by Einstein’s theory of relativity. One of the best sources of gravitational waves is binary black hole mergers, which are among the most violent events in the universe. On September 14 2015, Advanced LIGO (Laser Interferometer Gravitational-wave Observatory) successfully made the first gravitational wave detection. Since then, LIGO and Virgo have published four additional observations of gravitational waves from merging black holes. This poster presents a visualization of the merging black holes that LIGO and Virgo have observed so far, created by solving Einstein's equations of general relativity on supercomputers. This is the only way to model merging black holes, because all approximations fail near the time of merger. The video shows calculations of the black holes’ horizons and the emitted gravitational waves during the final few orbits as they spiral inwards, merge and ring down. Each calculation is consistent with one of the LIGO-Virgo observations. |
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E03.00007: Parameter Estimation of Gravitational Waves of Binary Neutron Star Mergers Using Lalinference Erick Leon The first gravitational waves emitted by a neutron star binary coalescence was detected on August 17, 2017. Being able to estimate the parameters of such a system including mass, and tidal deformation is an important factor in understanding the physics of neutron stars. Lalinference is a parameter estimation tool used to estimate parameters from gravitational wave signals. By using other computational methods to create fake gravitational wave signals we can test the capability of Lalinference to predict the correct parameters of these gravitational waves for some given noise spectrum. In my project, I ran Lalinference parameter estimation on several fake gravitational wave signals and compared the predicted parameters with the ones used to create the fake signals. This research can be used to predict the scientific capabilities of future observing runs for advanced interferometers. |
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E03.00008: Do micro-crystals cause point scattering in LIGO optics? Jazlyn G Guerrero, Joshua R Smith, Juan Rocha, Dakota Rose, Amy Gleckl, Michelle Aleman The Laser Interferometer Gravitational-wave Observatory (LIGO) has expanded astronomy by observing gravitational waves from merging black holes and neutron stars. Optical scatter reduces LIGO's astronomical reach by decreasing the laser power in its optical cavities and causing non-linear noise. A key component of optical scatter originates from point-like defects in the amorphous coating layers on LIGO optics. It is possible that these points originate from micro crystals formed before or during the annealing process used by LIGO, in which optics are heated to 500 C to improve their mechanical and optical absorption properties. This poster describes the development of a new experiment to address whether micro crystals are formed or grow as optics are heated |
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E03.00009: Numerical Simulation Infrastructure For Gravitational Wave Data Analysis Derek D White, Jocelyn Samantha Read The first gravitational waves from a merger of a binary neutron star system were detected less than a year ago, on August 17th 2017. This is still the only detection of gravitational waves involving neutron stars to date. Like binary black holes (BBH), investigations of binary neutron stars (BNS) rely on numerical simulations for the most accurate understanding of waveform dynamics at merger. Driven by several BBH detections to date, infrastructure for this analysis has been developed primarily for BBH. Meanwhile, infrastructure for BNS waveforms have not yet been fully incorporated. Using a standalone Python script, numerical binary neutron star mergers from third parties can now be converted into a format that can be uploaded and used inside the collaborative LALSuite/PyCBC projects to analyze the effects of numerical merger on searches and parameter estimation. The first examples of hybrid waveforms have also been generated using this system. |
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E03.00010: Visualizing the Curvature of Spacetime: Vortex and Tendex Lines of Head-On Merging Binary Black Hole Systems Samuel Rodriguez, Geoffrey Lovelace A black hole forms when a massive star can no longer support the thermonuclear processes in its core that hold it up against its gravity. Inside a black hole's horizon, nothing can escape. Merging black holes and the gravitational waves---ripples of curved spacetime---they emit are the most promising sources for gravitational-wave detectors like Advanced LIGO. When black holes merge, the spacetime around them becomes curved in a dynamic, turbulent way, like a storm in spacetime. In this project, we use analogs of electric and magnetic field lines to visualize the curved spacetime of merging black holes. A non-spinning black hole will produce Tendicity; along tendex lines (analogs of electric field lines), objects are stretched and squeezed. A spinning black hole will produce Tendicity but will also twist the spacetime around it, producing vorticity; along vortex lines (analogs of magnetic field lines), objects are twisted. We produce simulations and visualizations of equal mass black hole merging with no spin, and produce visualizations of vortex and tendex lines showing how the curved spacetime behaves as the holes merge. The intent is to gain some intuition of the dynamics of spacetime around binary black holes. |
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E03.00011: Neutron Star Measurements in Third Generation Gravitational Wave Observatories Isabella S Molina, Eric Flynn, Erick Leon, Jocelyn Samantha Read When dense objects in space orbit each other and merge they produce ripples in space-time called gravitational waves. Last year gravitational waves from neutron stars were detected. Several proposals for third generation gravitational-wave detectors were analyzed to determine their capabilities and accuracy in detecting binary neutron-star mergers and measuring their properties. This research compares the future detectors A+, A++, Cosmic Explorer1, Cosmic Explorer2 Wide and Narrow, the Einstein Telescopes B and D, Vrt, and Voyager to the current Advanced LIGO. The inspiral analysis aimed to determine the optimal frequency range for the detectors to observe the inspiral of two neutron stars. The inspiral part of the wave occurs when two neutron stars orbit each other and get closer to merging and the post merger begins after they have collided. The post merger analysis used several equations of state and determined the frequency range that gave the clearest SNR and best results for making analysis on the EOS’s. SNR values indicate whether or not the post merger would be distinguishable from the noise. This analysis will determine which detector configurations are best for measuring properties of neutron star matter. |
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E03.00012: Wind Proofing LIGO Elyssa Hofgard, Edgard L Bonilla Carrasquel, Brian T Lantz To reduce problematic wind that contributes to ground tilt, LIGO has proposed building a 50% porous fence around End Station X. We employed experimental and computational methods to evaluate the proposed fence. First, we tested different fence materials with a fan and a wind tunnel. Both materials reduced wind speed by about 50%, so the main differences will arise from cost and material strength. Next, we employed Computational Fluid Dynamics (CFD) modeling to evaluate the wind load on End Station X with and without a porous fence. We found that the fence is quite effective in reducing the load on the building. Models show that with a fence, problematic wind speeds could be above 20 m/s, which only occur 1.54% of the time. We then gathered data from the test fence at LIGO Hanford and compared it to steady-state and transient CFD models. We found that the steady state models are in good agreement with the measurements. However, the transient model shows variability than the real data, suggesting that the fence may smooth wind flow. A 50% porous fence is a well motivated wind proofing measure for End Station X, yet more robust model verification should be completed. |
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E03.00013: Experimentally exploring micro-crystallization in LIGO optics. Dakota Rose, Joshua R Smith, Jazlyn G Guerrero, Juan A Rocha, Amy Gleckl, Michelle Aleman The Laser Interferometer Gravitational Wave Observatory's (LIGO's) observations of gravitational waves from astronomical objects have opened a new field of astronomy. Optical scatter in LIGO reduces the detector's optical power and thus its astronomical reach. One possible source of this scattered light is micro-crystallization in the LIGO optics as a result of the annealing process they go through, in which they are heated to 500ºC to reduce thermal noise and material stresses. This poster presents an experiment designed to explore micro-crystallization in the LIGO optics by imaging scattered light while each optic is being heated. In particular, it describes work done to develop the apparatus and the instrument's current status. |
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E03.00014: Simulating Black Hole-Neutron Star Mergers Jennifer Helen Sanchez Gravitational waves are ripples in space and time predicted by Einstein’s theory of relativity; in 2015, Advanced LIGO observed these waves passing through Earth for the first time. We hope to observe black hole-neutron star (BHNS) mergers for they are “multi-messengers,” emitting both electromagnetic and gravitational waves. Highly accurate descriptions of these waves are crucial for helping experiments to detect gravitational waves from BHNS mergers. Using the Spectral Einstein Code, we are modeling BHNS mergers for different binaries, computing emitted gravitational waves, properties of the black hole before, during, and after the merger, and behaviors of the neutron-star matter as it is torn apart. So far, we have focused on low-mass mergers with non-spinning black holes, a case where tidal effects on the emitted gravitational waves are especially strong. In the future, we will extend this work to rapidly spinning merging black holes. |
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E03.00015: Very High Energy Gamma Ray Research on Blazars Jamil Batshoun Blazars are active galactic nuclei that emit a relativistic jet pointed very nearly in the direction of the Earth. They are believed to result from super massive black holes and as such present a very unique opportunity to study physics in an extreme environment. With data collected by VERITAS (Very Energetic Radiation Imaging Telescope Array System) in the very high energy (50 GeV - 50 TeV) range, analysis has begun on detecting and categorizing blazars throughout the cosmos. |
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E03.00016: Neutron Star: Equations of State, Phase Transitions, and the MIT Bag Model Marc Salinas, Thomas Klaehn Neutron stars are among the densest objects in the universe. The uncertainty of the internal structure of these stars have led to different ideas for modeling the core of these stars. Such different structures investigated include a purely nuclear core and a core composed of two layers, an inner quark plasma and a nuclear outer core. To model the quark core, the MIT bag model EoS will be explored to see the effect the bag pressure constant has on the different possible star configurations. With an equation of state for both the nuclear and quark layers of the core, we can assume the star is in an equilibrated state and perform a maxwell construction for the phase transition from nuclear to quark matter. Although the core is the main focus of the research, the crust is also explored, as well as it's resulting effect on the Mass and Radius. The results are different Mass-Radius curves that we can compare with observation and high energy collision experiments. In the meantime, a more sophisticated extended MIT bag model is currently being explored where vector interactions are taken into account and the resulting star configurations can vary dramatically. |
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E03.00017: CCD Characterization in the LSST Camera April Nuestro Starting in 2020, the Large Synoptic Survey Telescope (LSST) will be operated by astrophysicists all around the world to learn more about the grand universe. Images are taken by the LSST camera through a set of about 200 photosensors called charge-coupled devices (CCDs). In order to work most efficiently in preparation for the survey, the LSST team at SLAC National Accelerator Laboratory is undergoing data analysis with images produced by a spot projector. For now, this research focuses primarily on detecting objects in adjacent CCD images, placing those objects in a universal coordinate system, and gathering data on the objects in that image. Ultimately, these CCDS should accurately function for images of galaxies, stars, and more space objects taken by the LSST camera. |
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