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Cosmology, Relativity, and Gravity Commons

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All Articles in Cosmology, Relativity, and Gravity

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Gravitational Wave Behavior At A Vacuum-Matter Interface, Jake Litterer 2017 University of Puget Sound

Gravitational Wave Behavior At A Vacuum-Matter Interface, Jake Litterer

Honors Program Theses

In classical electrodynamics, boundary conditions of the E and B fields are derived from Maxwell's equations, which are used to derive the Fresnel equations describing the behavior of a wave at an interface between media with given indices of refraction. Though electrodynamics and gravity are in some instances strikingly analogous, boundary conditions in general relativity are somewhat more opaque. We will see that while while continuity of the metric must be true in general, discontinuity of the extrinsic curvature of spacetime, while allowed by the Einstein field equations, results in a singularity in the energy-momentum tensor. This singularity is ...


Literature Review: Biomimetic And Conventional Aircraft Wing Tips, Naseeb Ahmed Siddiqui, Waqar Asrar, Erwin Sulaeman 2017 International Islamic University - Malaysia

Literature Review: Biomimetic And Conventional Aircraft Wing Tips, Naseeb Ahmed Siddiqui, Waqar Asrar, Erwin Sulaeman

International Journal of Aviation, Aeronautics, and Aerospace

This paper is an attempt to summarize the effect of wing tip devices employed by birds, as well as aeronautical engineers in the past to improve the performance characteristics of aircraft. The focus is on reduction of the induced drag or drag due to lift also known as inviscid drag. This paper will provide an insight on both biomimetic and conventional wing tip approaches to reduce the induced drag. Prior analysis and experiments on the aerodynamics of airplane performance due to both these separate studies have been discussed. The needs of the industry and their past inventions have been described ...


Fermi-Lat Daily Monitoring Observations Of The Microquasar Cygnus X-1, Austin P. Waldron, Stephen R. Hood, Arash Bodaghee 2017 Georgia College and State University

Fermi-Lat Daily Monitoring Observations Of The Microquasar Cygnus X-1, Austin P. Waldron, Stephen R. Hood, Arash Bodaghee

Georgia College Student Research Events

Detection of gamma-ray emission from microquasars is important for understanding particle acceleration in the jet, and for constraining leptonic/hadronic emission models. We present a continuation of a 1-d likelihood analysis on gamma-ray observations by Fermi-LAT (0.1-10 GeV) of the accreting black hole candidate Cygnus X-1. Combining this gamma-ray data with available X-ray monitoring data from Swift and MAXI allowed us to reveal over a dozen days (in 2008-2016) during which Cyg X-1 displayed low-significance (3-4 sigma) excesses, many of which were contemporaneous with apparent transitions in the X-rays.


Vacuum.Doc, Vildyan Yanbikov 2017 Yanbikov Vildyan Shavkyatovich

Vacuum.Doc, Vildyan Yanbikov

Vildyan Yanbikov

The calculated density of the physical vacuum. The high density of physical vacuum.              


Evolution Of Cosmic Filaments And Of Their Galaxy Population From Mhd Cosmological Simulations., C. Gheller, F. Vazza, M. Brüggen, M. Alpaslan, Benne W. Holwerda 2017 Swiss National Supercomputing Centre

Evolution Of Cosmic Filaments And Of Their Galaxy Population From Mhd Cosmological Simulations., C. Gheller, F. Vazza, M. Brüggen, M. Alpaslan, Benne W. Holwerda

Benne Holwerda

Despite containing about a half of the total matter in the Universe, at most wavelengths the filamentary structure of the cosmic web is difficult to observe. In this work, we use large unigrid cosmological simulations to investigate how the geometrical, thermodynamical and magnetic properties of cosmological filaments vary with mass and redshift (z ≤ 1). We find that the average temperature, length, volume and magnetic field of filaments scales well with their total mass. This reflects the role of self-gravity in shaping their properties and enables statistical predictions of their observational properties based on their mass. We also focus on the ...


Statistical Modeling And Beam Analysis For The Redshifted Global 21 Centimeter Signal, Katherine Pellicore 2017 University of Colorado, Boulder

Statistical Modeling And Beam Analysis For The Redshifted Global 21 Centimeter Signal, Katherine Pellicore

Undergraduate Honors Theses

This thesis explores two aspects of measurements of the global 21 cm signal through analytical simulations. We first attempt to understand how well the global 21 cm signal could be extracted from measurements of the sky. We accomplish this by employing a Fisher matrix analysis to estimate the uncertainties of cosmological parameters for simple measurement models that assume a perfectly calibrated instrument. We find that the assumed parameters of the signal can be constrained to high precision under realistic scenarios of noise and foreground contaminants. We also study the bias in the cosmological parameters due to modeling errors using a ...


Short-Period Mesospheric Gravity Waves And Their Sources At The South Pole, Dhvanit Mehta, Andrew J. Gerrard, Yusuke Ebihara, Allan T. Weatherwax, Louis J. Lanzerotti 2017 Merrimack College

Short-Period Mesospheric Gravity Waves And Their Sources At The South Pole, Dhvanit Mehta, Andrew J. Gerrard, Yusuke Ebihara, Allan T. Weatherwax, Louis J. Lanzerotti

Physics Faculty Publications

The sourcing locations and mechanisms for short-period, upward-propagating gravity waves at high polar latitudes remain largely unknown. Using all-sky imager data from the Amundsen–Scott South Pole Station, we determine the spatial and temporal characteristics of 94 observed small-scale waves in 3 austral winter months in 2003 and 2004. These data, together with background atmospheres from synoptic and/or climatological empirical models, are used to model gravity wave propagation from the polar mesosphere to each wave's source using a ray-tracing model. Our results provide a compelling case that a significant proportion of the observed waves are launched in several ...


Quantum Foundations With Astronomical Photons, Calvin Leung 2017 Harvey Mudd College

Quantum Foundations With Astronomical Photons, Calvin Leung

HMC Senior Theses

Theoretical work in quantum information has demonstrated that a classical hidden-variable model of an entangled singlet state can explain nonclassical correlations observed in tests of Bell’s inequality if while measuring the Bell correlation, the underlying probability distribution of the hidden-variable changes depending on the measurement basis. To rule out this possibility, distant quasars can be utilized as random number generators to set measurement bases in an experimental test of Bell’s inequality. Here we report on the design and characterization of a device that uses the color of incoming quasar photons to output a random bit with nanosecond latency ...


Series Solutions Of Polarized Gowdy Universes, Doniray Brusaferro 2017 Virginia Commonwealth University

Series Solutions Of Polarized Gowdy Universes, Doniray Brusaferro

Theses and Dissertations

Einstein's field equations are a system of ten partial differential equations. For a special class of spacetimes known as Gowdy spacetimes, the number of equations is reduced due to additional structure of two dimensional isometry groups with mutually orthogonal Killing vectors. In this thesis, we focus on a particular model of Gowdy spacetimes known as the polarized T3 model, and provide an explicit solution to Einstein's equations.


Elasticity Of Cylindrical Black Holes, Conrad Pearson 2016 California Polytechnic State University, San Luis Obispo

Elasticity Of Cylindrical Black Holes, Conrad Pearson

Physics

Black holes are regions of strong gravity, and are often regarded as behaving like drops of fluid. When this line of thought is applied to cylindrical black holes (black cylinders), a mapping can be made between known instabilities for black cylinders and ordinary fluid cylinders. However, this known correlation is increasingly less accurate for lower spatial dimensions, and I seek to correct this discrepancy in this thesis. By considering soft solids instead of pure fluids, elastic energy can be included, which brings us closer to a direct comparison. In improving this mapping, it becomes possible to better understand the behavior ...


Probing Dark Matter-Neutrino Connection Via Indirect Detection Experiments, Bradley Knockel 2016 University of New Mexico

Probing Dark Matter-Neutrino Connection Via Indirect Detection Experiments, Bradley Knockel

Physics & Astronomy ETDs

Various evidence reveals that dark matter is a primary component of this universe. The amount of dark matter is known, but its identity is a mystery. To determine its properties, efforts to detect and produce dark matter are underway. Dark matter annihilations throughout the galaxy may produce photons, neutrinos, and cosmic rays. Neutrino and photon detectors may then indirectly detect dark matter by detecting these annihilation products. The annihilation rate, dark matter mass, and dark matter scattering rate off of matter affect the signals received at Earth. These signals can therefore probe the identity of dark matter, especially if dark ...


Rethinking The Polar Cap: Eccentric Dipole Structuring Of Ulf Power At The Highest Corrected Geomagnetic Latitudes, Kevin D. Urban, Andrew J. Gerrard, Louis J. Lanzerotti, Allan T. Weatherwax 2016 Merrimack College

Rethinking The Polar Cap: Eccentric Dipole Structuring Of Ulf Power At The Highest Corrected Geomagnetic Latitudes, Kevin D. Urban, Andrew J. Gerrard, Louis J. Lanzerotti, Allan T. Weatherwax

Physics Faculty Publications

The day-to-day evolution and statistical features of Pc3-Pc7 band ultralow frequency (ULF) power throughout the southern polar cap suggest that the corrected geomagnetic (CGM) coordinates do not adequately organize the observed hydromagnetic spatial structure. It is shown that that the local-time distribution of ULF power at sites along CGM latitudinal parallels exhibit fundamental differences and that the CGM latitude of a site in general is not indicative of the site's projection into the magnetosphere. Thus, ULF characteristics observed at a single site in the polar cap cannot be freely generalized to other sites of similar CGM latitude but separated ...


Introduction To Classical Field Theory, Charles G. Torre 2016 Department of Physics, Utah State University

Introduction To Classical Field Theory, Charles G. Torre

All Complete Monographs

This is an introduction to classical field theory. Topics treated include: Klein-Gordon field, electromagnetic field, scalar electrodynamics, Dirac field, Yang-Mills field, gravitational field, Noether theorems relating symmetries and conservation laws, spontaneous symmetry breaking, Lagrangian and Hamiltonian formalisms.


Black Holes Modeled As Fluid Droplets On Membranes, Anthony Bardessono 2016 California Polytechnic State University, San Luis Obispo

Black Holes Modeled As Fluid Droplets On Membranes, Anthony Bardessono

Physics

No abstract provided.


Possible Evolution Of Supermassive Black Holes From Fri Quasars, Matthew I. Kim, Damian J. Christian, David Garofalo, Jaclyn D'Avanzo 2016 California State University, Northridge

Possible Evolution Of Supermassive Black Holes From Fri Quasars, Matthew I. Kim, Damian J. Christian, David Garofalo, Jaclyn D'Avanzo

Faculty Publications

We explore the question of the rapid buildup of black hole mass in the early universe employing a growing black hole mass-based determination of both jet and disc powers predicted in recent theoretical work on black hole accretion and jet formation. Despite simplified, even artificial assumptions about accretion and mergers, we identify an interesting low probability channel for the growth of one billion solar mass black holes within hundreds of millions of years of the big bang without appealing to super Eddington accretion. This result is made more compelling by the recognition of a connection between this channel and an ...


Schwarzschild Spacetime And Friedmann-Lemaitre-Robertson-Walker Cosmology, Zachary Cohen 2016 University of Connecticut - Storrs

Schwarzschild Spacetime And Friedmann-Lemaitre-Robertson-Walker Cosmology, Zachary Cohen

Honors Scholar Theses

The advent of General Relativity via Einstein's field equations revolutionized our understanding of gravity in our solar system and universe. The idea of General Relativity posits that gravity is entirely due to the geometry of the universe -- that is, the mass distribution throughout the universe results in the ``curving" of spacetime, which gives us the physics we see on a large scale. In the framework of General Relativity, we find that the universe behaves differently than was predicted in the model of gravitation developed by Newton. We will derive the general relativistic model for a simple system near a ...


Bondi Accretion In Trumpet Geometries, August J. Miller 2016 Bowdoin College

Bondi Accretion In Trumpet Geometries, August J. Miller

Honors Projects

The Bondi solution, which describes the radial inflow of a gas onto a non-rotating black hole, provides a powerful test for numerical relativistic codes. However, this solution is typically derived in Schwarzschild coordinates, which are not well suited for dynamical spacetime evolutions. Instead, many current numerical relativistic codes adopt moving-puncture coordinates, which render black holes in trumpet geometries. Here we transform the Bondi solution into two different trumpet coordinate systems, both of which result in regular expressions for the fluid flow extending into the black hole interior. We also evolve these solutions numerically and demonstrate their usefulness for testing and ...


Topics In The Detection Of Gravitational Waves From Compact Binary Inspirals, Shasvath Jagat Kapadia 2016 University of Arkansas, Fayetteville

Topics In The Detection Of Gravitational Waves From Compact Binary Inspirals, Shasvath Jagat Kapadia

Theses and Dissertations

Orbiting compact binaries - such as binary black holes, binary neutron stars and neutron star-black hole binaries - are among the most promising sources of gravitational waves observable by ground-based interferometric detectors. Despite numerous sophisticated engineering techniques, the gravitational wave signals will be buried deep within noise generated by various instrumental and environmental processes, and need to be extracted via a signal processing technique referred to as matched filtering.

Matched filtering requires large banks of signal templates that are faithful representations of the true gravitational waveforms produced by astrophysical binaries. The accurate and efficient production of templates is thus crucial to the ...


Better Together, 2016 DePaul University

Better Together

DePaul Magazine

Faculty have taken full advantage of the university's innovative intercollegiate grant program, and the resulting research is as interesting and diverse as the collaborators themselves. What is resulting is research on "Patient and Primary Care Provider Perspectives on Recreational and Therapeutic Cannabis Use Within a Changing Socioculltural and Political Context;" a new minor in climate change science and policy; a new class, Communication, Coding and Entrepreneurship; brain inflammation research; and the project "Cosmology Meets Continental Philosophy: Natural Laws and Why There Is Something Rather Than Nothing"


The Geometry Of Spacetime And Its Singular Nature, Filip Dul 2016 University of Connecticut

The Geometry Of Spacetime And Its Singular Nature, Filip Dul

Honors Scholar Theses

One hundred years ago, Albert Einstein revolutionized our understanding of gravity, and thus the large-scale structure of spacetime, by implementing differential geometry as the pri- mary medium of its description, thereby condensing the relationship between mass, energy and curvature of spacetime manifolds with the Einstein field equations (EFE), the primary compo- nent of his theory of General Relativity. In this paper, we use the language of Semi-Riemannian Geometry to examine the Schwarzschild and the Friedmann-Lemaˆıtre-Robertson-Walker met- rics, which represent some of the most well-known solutions to the EFE. Our investigation of these metrics will lead us to the problem of ...


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