Bulletin of the American Physical Society
APS April Meeting 2012
Volume 57, Number 3
Saturday–Tuesday, March 31–April 3 2012; Atlanta, Georgia
Session X7: Neutron Stars and General Astrophysics |
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Sponsoring Units: DAP Chair: Pablo Laguna, Georgia Institute of Technology Room: Embassy D |
Tuesday, April 3, 2012 1:30PM - 1:42PM |
X7.00001: Photoionization and Electron-Ion Recombination of Fe~XVII for High Temperature Plasmas Sultana Nahar Earlier studies on electron-ion recombination of Fe~XVII, $e+ Fe~XVIII \rightarrow~Fe~XVII$, concentrated on low temperature region. However, due to its higher abundace, recombination in the high temperature region such as one exists in solar convection zone is of great importance. Total and level-specific recombination cross sections and rates of Fe~XVII are presented from the detailed study in the high temperature. The calculations were carried out using the unified method which incorporates both the radiative recombination (RR) and dielectronic recombination (DR) including the interference effects and provides self-consistent set of recombination rates and photoionization cross sections. The calculations included core excitations of levels n=2 and 3 complexes in contrast to earlier consideration of the n=2 levels only, and hence entails a large energy range and high temperature range. Resonances due to core excitations to n=3 levels are much more extensive and stronger than those to n=2 levels. These have introduced a broad and high FR peak at about 5$\times 10^6$ K. [Preview Abstract] |
Tuesday, April 3, 2012 1:42PM - 1:54PM |
X7.00002: Determining the temporal dynamics of the solar $\alpha$ effect Andrew Newton, Eun-jin Kim We use observations of solar activity to constrain parameters relating to the $\alpha$ effect in stochastic nonlinear dynamo models. This is achieved through performing a comprehensive statistical comparison by computing probability distribution functions (PDFs) of solar activity from observations and from our simulation of $\alpha-\Omega$ mean field dynamo model. The observational data that are used are the time history of solar activity inferred for C14 data in the past 11000 years on a long time scale and direct observations of the sun spot numbers obtained in recent years 1795-1995 on a short time scale. Monte Carlo simulations are performed on these data to obtain probability distribution functions (PDFs) of the solar activity on both long and short time scales. These PDFs are then compared with PDFs from numerical simulation of our $\alpha-\Omega$ dynamo model, where $\alpha$ is assumed to have both mean $\alpha_0$ and fluctuating $\alpha'$ parts. By varying the correlation time of fluctuating $\alpha'$, the ratio of the amplitude of the fluctuating to mean alpha and the ratio of poloidal to toroidal magnetic fields, we show that the results from our stochastic dynamo model can match the PDFs of solar activity on both long and short time scales. [Preview Abstract] |
Tuesday, April 3, 2012 1:54PM - 2:06PM |
X7.00003: Resonant Shattering of Neutron Star Crusts David Tsang, Jocelyn Read, Tanja Hinderer, Anthony Piro The resonant excitation of neutron star (NS) modes by tides is investigated as a source of short gamma-ray burst (SGRB) precursors. We find that the driving of a crust-core interface mode can lead to shattering of the NS crust, liberating $10^{46}-10^{47}$ erg of energy seconds before the merger of a NS-NS or NS-black-hole binary. Such properties are consistent with Swift/BAT detections of SGRB precursors, and we use the timing of the observed precursors to place weak constraints on the crust equation of state. We describe how a larger sample of precursor detections could be used alongside coincident gravitational wave detections of the inspiral by Advanced LIGO class detectors to probe the NS structure. These two types of observations nicely complement one another, since the former constrains the equation of state and structure near the crust-core boundary, while the latter is more sensitive to the core equation of state. [Preview Abstract] |
Tuesday, April 3, 2012 2:06PM - 2:18PM |
X7.00004: The Impact of Magnetic Screening on Neutron Star Crusts Joseph Hughto, Jos\'e Pons, Charles Horowitz Strong magnetic fields in the outer crust of neutron stars can screen the interactions between ions. This may change the structure of the crystal and lead to anisotropic energy transport which can be important for the modeling of observations. We take the results of Sharma \& Reddy (2010) and apply their screened potential using Molecular Dynamics simulations and study the structure of the crystal and also transport properties. [Preview Abstract] |
Tuesday, April 3, 2012 2:18PM - 2:30PM |
X7.00005: ABSTRACT WITHDRAWN |
Tuesday, April 3, 2012 2:30PM - 2:42PM |
X7.00006: Equation for the Origin of Spiral Galactic Formation and Rotation Stewart Brekke Already formed galactic arms existed in sets of two or more orbiting each other due to the Big Bang. As the orbits of the arms decayed due to gravitational attraction they attached in their fore sections tangentially accreting forming spiral galaxies which began to rotate due to the transformation of the orbital motion of the pre-galactic arms into the rotational motion of the newly formed spiral galaxy. If $I_1\omega_1$, $I_2\omega_2$, and $I_n\omega_n$ are the angular momentums of the pre-galactic arms, and $(I\omega)_{galaxy}$ is the angular momentum of the newly formed spiral galaxy, the equation for the formation and origin of spiral galaxy rotation is $I_1\omega_1 + I_2\omega_2 +...+ I_n\omega_n = (I\omega_{galaxy})$. [Preview Abstract] |
Tuesday, April 3, 2012 2:42PM - 2:54PM |
X7.00007: Boson Star Lensing at the Center of the Galaxy Amitai Bin-Nun Observations of the Sgr A* region in the galactic center have implied a large amount of matter in a small volume, leading to the assumption of a black hole at Sgr A*. However, dynamical observations cannot rule out the presence of a boson star, a compact object made up of scalar particles, as both objects are far more compact than current observational resolutions. While a boson star in the galactic center is disfavored for a number of theoretical considerations, we outline the first test that can directly observe a boson star. We accomplish this by studying strong gravitational lensing by boson stars, taking advantage of the fact that boson stars have an extended mass distribution that gives rise to a radial caustic curve and are transparent to electromagnetic radiation. We calculate the brightness of images formed by stars crossing these radial caustics and show that a boson star can give rise to much brighter images than a black hole with a similar mass. [Preview Abstract] |
Tuesday, April 3, 2012 2:54PM - 3:06PM |
X7.00008: Gravitational Repulsion of Photons Ari Brynjolfsson Plasma redshift explains the cosmological redshift, the redshift of stars and galaxies, the cosmic microwave background, the cosmic X-ray background, the observed redshift relation for magnitude and surface-brightness for supernovae, the solar redshift, the transition zone for the solar corona, the high temperatures of the solar corona. Plasma redshift makes it clear that the optical solar lines are not gravitationally redshifted when observed on Earth. Instead their gravitational redshifts in the Sun are reversed, as the photons travel from the Sun to the Earth. This means that the photons are repelled and not attracted by the gravitational field. There is, therefore, no need for Einstein's Lambda for explaining the static Universe. When the matter concentrates and falls towards the center of galaxies, it becomes so hot that it disintegrates matter to reform primordial like matter. In this way the universe can renew itself forever. This is all based on conventional physics, using only more accurate physics and calculations than those usually used. There is no need for Dark Energy, Dark Matter, Accelerated Expansion, nor Black Holes for explaining the everlasting Universe. [Preview Abstract] |
Tuesday, April 3, 2012 3:06PM - 3:18PM |
X7.00009: Theory of Everything (TOE): scalar potential model John Hodge The inconsistency of quantum mechanics and general relativity has made the development of a Theory of Everything (TOE) difficult. A candidate scalar potential TOE (STOE) is presented. The model is applied to photon diffraction; to the rotation curves, central mass and redshift of galaxies; to the Pioneer anomaly; and to the temperature of the microwave background radiation. The STOE explains many mysterious phenomena from diverse observational disciplines. Predictions of the STOE in 2006 that no other model predicted have been published in 2011. [Preview Abstract] |
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