Bulletin of the American Physical Society
Joint Spring 2016 Meeting of the Texas Sections of APS, AAPT, and Zone 13 of the SPS
Volume 61, Number 3
Thursday–Saturday, March 31–April 2 2016; Beaumont, Texas
Session F1: APS Session - Space Science, Astronomy and Cosmology |
Hide Abstracts |
Chair: Stephen Bradshaw, Rice University Room: 206 |
Saturday, April 2, 2016 10:30AM - 10:54AM |
F1.00001: Constraints on Macroscopic Gravity from Planck Invited Speaker: Tharake Wijenayake We use the exact and covariant averaging framework of macroscopic gravity (MG) to study the relativistic corrections to cosmology due to non-linear phenomena occurring at small scales. We present constraints on MG using the cosmic microwave background (CMB) temperature anisotropy data from Planck, and other cosmological probes. For the MG model, the effects of small-scale structure on the homogeneous and isotropic background and the evolution of large-scale structure can be encapsulated by just one parameter ($\Omega_\mathcal{A}$). We find that $\Omega_\mathcal{A}$ is close to consistent with zero and can be constrained to $-0.03 \le \Omega_{\mathcal{A}} \le 0$ (at the 95\% CL). The strong correlation between $\Omega_\mathcal{A}$ and $\Omega_\Lambda$, $\sigma_8$ and $H_0$, leads to significant increase in the error bars associated with those values. [Preview Abstract] |
Saturday, April 2, 2016 10:54AM - 11:06AM |
F1.00002: Testing modified gravity theories using Tensor Perturbation Weikang Lin, Mustapha Ishak Primordial gravitational waves are promising to deliver a new and powerful window to probe the physics of the early universe and gravity. In modified gravity theories, tensor perturbation can propagate with an additional friction or a non-standard dispersion relation. Keeping the friction a constant, we parameterize the dispersion relation in three ways. While the constant dispersion parametrization corresponds to a constant speed and the low $k/a$ parametrization coincides with a massive gravity model, the high $k/a$ parametrization has not been studied in the literature. Current available data give excluded regions in the $r$ and modified gravity parameter spaces. With a performance forecast and $r_{fid}=0.005$, we found that if no deviation from G COrE will limit significantly the allowed modified gravity parameter spaces. Specially, the minimum detectible graviton mass for COrE is about $7\times10^{-33}eV$, which is of the same order of magnitude as the graviton mass should massive gravity be responsible for the late time acceleration of the universe. We also study the tensor perturbation during inflation with our parameterization. [Preview Abstract] |
Saturday, April 2, 2016 11:06AM - 11:18AM |
F1.00003: Response Time of the Ionosphere to Sign Changes in the Interplanetary Magnetic Field Y-Component Christopher Sherrill, Mikayla Streetman, Kevin Pham, Ramon Lopez The solar wind travels from the Sun to the Earth carrying the interplanetary magnetic field (IMF) with it. When the solar wind reaches Earth, the interaction between the IMF and the Earth's magnetic field produces a current system throughout the magnetosphere, which connects to the ionosphere. We have identified events when the y-component of the IMF reverses direction in a short amount of time. We will take these events and use AMPERE to measure how long it takes for the ionosphere to reconfigure. AMPERE processes data from the iridium satellites to create a map of the field-aligned currents in the ionosphere. We will also measure the time of this transition in the ionosphere using Super Dual Auroral Radar Network (SuperDARN). SuperDARN is a network of ground radar that measures charged particle movement in the ionosphere. We will present a comparison of the transition times found using AMPERE with those from SuperDARN. [Preview Abstract] |
Saturday, April 2, 2016 11:18AM - 11:30AM |
F1.00004: Examining Ionospheric Potential Patterns Due to Sudden Changes in the IMF Y-component Mikayla Streetman, Christopher Sherrill, Kevin Pham, Ramon Lopez The continuous flow of particles out from the Sun is known as the solar wind. As the solar wind travels to the Earth, it carries with it the interplanetary magnetic field (IMF). The interaction between the IMF and the Earth's magnetic field produces a current system in the ionospheric current regions. We will find events where the IMF changes from east to west or west to east in less than five minutes. In addition, the IMF before and after these events must be relatively steady, preferably unchanged by more than 2nT. We will then examine the ionospheric electrostatic potentials produced by the Super Dual Auroral Radar Network (SuperDARN) and the Defense Meteorological Satellite Program (DMSP). SuperDARN is a network of ground based radars that observe the motion of the solar wind in the Earth's upper atmosphere beginning at mid-latitudes extending into the polar regions. DMSP is a satellite that travels through the polar regions and takes measurements of the ionosphere as it passes through. The time it takes for the ionospheric electrostatic potential to reconfigure will be calculated for both SuperDarn and DMSP. We will present a comparison of the times it takes for the transitions to occur. [Preview Abstract] |
Saturday, April 2, 2016 11:30AM - 11:42AM |
F1.00005: Propagation Time of Solar Wind Flow Pressure Spikes From Bow Shock to Ground Magnetometers Brizy Schock, Kevin Pham, Ramon Lopez The Sun is constantly emitting plasma known as solar wind. This wind has variations in the particle flow pressure that is measured with satellites in space. In our study we looked for instances of steady flow pressure followed by a sudden increase that occurred within 1 to 2 minutes that had an increase of a factor of 3 or more. After collecting these events we compare them to ground magnetometers at local noon. These variations in flow pressure condenses the near-Earth's magnetic field which is detected by observatories on the ground. We are looking at the distribution of time delays between the flow pressure changes in the solar wind and the changes in the ground magnetometers. This will allow us to estimate the uncertainty in timing using the OMNI data. [Preview Abstract] |
Saturday, April 2, 2016 11:42AM - 11:54AM |
F1.00006: The Black Hole(s) of \textit{Interstellar} Nathan Steinle, Donald Olson The movie \textit{Interstellar} walks a fine line between science fiction and scientific accuracy, and it generally excels on both sides. The release of the movie and its companion book, \textit{The Science of Interstellar} (2014) by Kip Thorne, generated much online conversation about attempts to replicate calculations underlying the film and the book. For Miller's planet, orbiting near the horizon of the rotating (Kerr) black hole Gargantua, three numerical quantities of interest are the time dilation factor (one hour on the planet corresponds to seven years on Earth), the location of the planet's orbit, and the speed in its orbit (given in Thorne's book as 0.55c). We use general relativistic equations to calculate these three quantities and explain discrepancies in online discussions of the speed of Miller's planet. Thorne mentioned that the makers of \textit{Interstellar }chose visual elegance over scientific consistency in depicting the accretion disk. A somewhat surprising result of our calculations is that multiple choices of the black hole's mass and spin parameters are required to match all the details of the film's plot and the numerical values in the book. [Preview Abstract] |
Saturday, April 2, 2016 11:54AM - 12:06PM |
F1.00007: Unification of Quantum Mechanics and General Relativity: Geometrical Nature of Matter and Multiple Levels of Universes shahram khosravi Spacetimematter is a five dimensional geometry where matter is baked into geometry as a new dimension. Every event point of spacetimematter follows the uncertainty principle, which limits the accuracy of the measurement of its space, time, and matter coordinates turning it into a Space-Time-Matter (STM) geometrical quantum with space, time, and matter edges. The Universe consists of a hierarchical levels of universes where each level has its own level of spacetimematter and quantum state functions. I'll show that non-ordinary matter and energy coming from the non-zeroth levels of universes together form the dark matter and dark energy. I'll present new quantum and general relativity field equations for each level of universe which together unify quantum mechanics and general relativity and the four fundamental forces of nature. I'll then use actual astronomical data and a simple theoretical model to derive the physical constants of the first level of universe and show that they vary from their counterparts in the zeroth level of universe (i.e. ordinary universe). I'll also provide a quantum mechanism for black hole characteristics such as singularity and space-time reversal and show how my approach resolves black hole information paradox. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700