Bulletin of the American Physical Society
76th Annual Meeting of the Southeastern Section of APS
Volume 54, Number 16
Wednesday–Saturday, November 11–14, 2009; Atlanta, Georgia
Session PB: Astrophysics and Gravitation |
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Chair: Paul Wiita, Georgia State University Room: Frankfurt |
Saturday, November 14, 2009 10:45AM - 10:57AM |
PB.00001: Moment of Inertia as a Sensitive Probe of the Equation of State Farrukh Fattoyev, Jorge Piekarewicz Several relativistic mean-field models will be employed to compute the equation of state of neutron-rich matter in $\beta-$equilibrium. Using this set of the equations the mass, radii, moments of inertia, {\sl etc.}, of an axisymmetric slowly rotating neutron stars in hydrostatic equilibrium will be computed. In particular, it will be shown which of these observables are sensitive to the choice of the equation of state. [Preview Abstract] |
Saturday, November 14, 2009 10:57AM - 11:09AM |
PB.00002: The Optical Variability of PKS 1510-089, PKS 1622-297 and AP Librae Diana Gudkova, Richard Miller, Joe Eggen, Jeremy Maune, Kevin Marshall The results of a five-year photometric monitoring program for the three southern hemisphere blazars, PKS 1510-089, PKS 1622-297 and AP Librae will be presented. Rapid, large amplitude variations are present on timescales ranging from less than a day to years. These variations will provide constraints on the emission mechanisms and the size of the emitting region. The implications of these results will be discussed. [Preview Abstract] |
Saturday, November 14, 2009 11:09AM - 11:21AM |
PB.00003: The Optical Variability of the Blazars OJ 287, 3C 279 and AO 0235 + 164 J.R. Eggen, H.R. Miller, D.O. Gudkova, J.D. Maune, K.B. Marshall We present the results of R-band time-series photometric measurements of following blazars obtained over the last two years: OJ 287, 3C 279, and PKS 0235+164. Our observations are comprised of short-term micro-variability studies obtained at Lowell Observatory and longer-term monitoring via the SMARTS Consortium. We combine these observations with historical data obtained by the PEGA group at Georgia State University over the past several years and perform an analysis of the power density spectrum (PDS) and extract the break frequencies for these objects. The constraints which these results provide on the emission mechanisms/processes will be discussed. [Preview Abstract] |
Saturday, November 14, 2009 11:21AM - 11:33AM |
PB.00004: Underlying Galaxy Subtraction of the Blazar PKS 2201+044 Jeremy Maune Results of the deconvolution of the central, non-thermal source of PKS 2201+044 from the surrounding elliptical galaxy will be presented. Differential photometry on this object was preformed on images obtained from telescopes belonging to the Lowell Observatory in Arizona and SMARTS in Chile. The central object was then extracted from the background source using the multiple aperture ``Galaxy Growth-Curve Given'' technique as described in Sandage (Ap. J.,180, 687-697, 1972). The impact on the perceived variability of the object - as well as comparisons to similar objects using both convolved and deconvolved data - is discussed. [Preview Abstract] |
Saturday, November 14, 2009 11:33AM - 11:45AM |
PB.00005: Possible Quasi-Periodic Oscillations in Blazars Paul Wiita, Haritma Gaur, Alok Gupta, Pawel Lachowicz We have examined x-ray light curves of several BL Lacertae objects and flat spectrum radio quasars, which together comprise the blazar class of active galaxies. This data was taken with the XMM-Newton satellite. Some of these light curves contain both red-noise at lower frequencies and a break toward white-noise at higher frequencies within the roughly day-like timescales of these observations. We have searched for quasi-periodic oscillations (QPOs) in these light curves using periodograms, structure functions and wavelets. In the case of the BL Lac PKS 2155$-$304, we find quite strong evidence for a QPO at roughly 4.6 hours for which the total amplitude is about 5\%. Because the total observation period was only 64 ks this includes only 3.8 cycles of this putative QPO and so the detection is not firm. Models involving shocks propagating down either relativistic turbulent jets or relativistic jets containing quasi-helical structures are able to explain such rapid quasi-periodic fluctuations in blazars because the amount of Doppler boosting can change substantially and quickly. [Preview Abstract] |
Saturday, November 14, 2009 11:45AM - 11:57AM |
PB.00006: A Survey of Stellar Families: Multiplicity of Solar-type Stars Deepak Raghavan, Harold McAlister We owe a lot to our Sun. The Earth was formed as a by-product of the Sun's birth and life on Earth is sustained by the Sun's energy. But our Sun is just one among billions. So we wonder -- is our Sun unique in harboring conditions favorable to life, or is the Universe, like the Earth, teeming with life? Do other Sun-like stars have planets? Do they have other stellar companions? My Ph.D. work was dedicated to answering these questions and in this talk, I will present the results. In the most comprehensive effort yet on this study, I analyzed 454 stars by synthesizing the vast body of knowledge about them and augmenting them with targeted new observations. The resulting statistics show that about 55{\%} of solar-type stars are even more Sun-like, for they are single, reversing prior expectations. Other results, consistent with expectations, show that younger stars are more likely to have companions, as are more massive stars. Stellar binaries seem to disproportionately favor twins, i.e. stars of nearly identical masses. The results also show that planets are as likely to form around single stars as they are around components of binary or multiple star systems, increasing the real estate available for planets, and perhaps life. [Preview Abstract] |
Saturday, November 14, 2009 11:57AM - 12:09PM |
PB.00007: Shape Modeling of Asteroids --A Worthwhile Endeavor for Smaller Observatories Michael Fauerbach Asteroids, are generally too small to visually distinguish their shape through Earth-bound observations. Fortunately, light curve inversion of disc-integrated photometry has been shown to be a viable source to obtain information about physical properties of asteroids, such as the shape and spin axis. In early 2007 two target candidates for an initial shape modeling study at the Egan Observatory at Florida Gulf Coast University were selected, namely Minor Planets 242 Kriemhild and 287 Nephthys. Shape models of these two asteroids will be presented. [Preview Abstract] |
Saturday, November 14, 2009 12:09PM - 12:21PM |
PB.00008: A new technique to determine the value of G Ming Yin, Michael Wescott, Dan Overcash, George Voulgaris, George Cokkinides, Pawel Morawiec, Timir Datta The Big-G or Newton's constant of universal gravitational was implied in the formulation of the law of gravitation proposed by Sir Isaac Newton in the Principia Mathematica (1687). G also appears in Albert Einstein's General Theory of relativity as well as in quantum theories of gravitation. It is the least precisely known fundamental constants of nature; the accuracy of its value (1/10,000) has increased only modestly since Cavendish. A dynamical experiment to measure G is in progress in our laboratory. Some of the challenging problems are the inability to shield background gravitation, knowledge of exact mass distribution and precise determination of time scale. Our technique, (i) explicitly corrects for tidal changes in the background, (ii) incorporates simple solid cylinder geometries, (iii) defines period of oscillation by Fourier analysis of the entire sets of time displacement data and (iv) the measurements are compared with numerical finite element analysis of test mass acceleration. A description of the apparatus and measurements will be presented. [Preview Abstract] |
Saturday, November 14, 2009 12:21PM - 12:33PM |
PB.00009: A Study of Tidal Acceleration James Gambrell, Michael Wescott, Ming Yin, Dan Overcash, George Voulgaris, Timir Datta Isaac Newton was the first to show the importance of tide as a source of astronomical information. He also calculated the ratio of lunar and solar masses from the heights of high and low tides at Plymouth. Not surprisingly his estimate was many orders of magnitude too high. Other objects in the Solar system also produce physical influence. We are fabricating several experimental apparatus to measure tidal acceleration in the laboratory. Also a theoretical vector technique to directly calculate the acceleration without the necessity of series expansions is developed. A preliminary report on the apparatus and measurements will be discussed. The acceleration data will be compared with the results, of (i) standard scalar potential calculations [T. Hartmann {\&} H.G. Wenzel, GeoPhys. Res. Lett. 22, 3553 (1995)] and (ii) vector calculations. It is posited that in (i) solar system astrometry, (ii) geo-positioning and (iii) time determination high-precision tidal accelometry can be competitive to other current techniques. [Preview Abstract] |
Saturday, November 14, 2009 12:33PM - 12:45PM |
PB.00010: Gravitational Polarization {\&} The Schiff-Dessler Controversy Pawel Morawice, Ming Yin, Michael Wescott, Dan Overcash, Timir Datta The behavior of composite matter in external fields can be very reveling. The quantum mechanical problem of an electrically conducting material object (test mass) placed in a uniform (weak) gravitational field, \textbf{\textit{g}}, was considered by many authors starting with Schiff [Phys. Rev. 151, 1067 (1966)]. Depending on the theoretical treatment opposing results of gravity induced (electric) field \textbf{\textit{E}}$_{g}$ have been reported. In the Schiff model [L.I. Schiff, PRB, \textbf{1}, 4649 (1970)] \textbf{\textit{E}}$_{g}$ is predicted to be oriented anti-parallel (with reference to \textbf{\textit{g}}). On the other hand it is found to be parallel in the more realistic elastic lattice model [A. J. Dessler et al, Phys.Rev, \textbf{168}, 737, (1968); Edward Teller, PNAS, \textbf{74}, 2664 (1977)]. Surprisingly, this contradiction has been largely overlooked by modern researchers. The preliminary results of an experimental study will be reported. Several interesting theoretical and technological implications will be suggested. [Preview Abstract] |
Saturday, November 14, 2009 12:45PM - 12:57PM |
PB.00011: Painleve'-Gullstrand models for time-dependent black holes Tehani Finch, James Lindesay Black hole metrics that contain a timelike Killing vector have well known causal structure, captured by Penrose diagrams. However, the causal structure of time-dependent black holes has only recently received significant attention. Penrose diagrams have now been constructed for models of black holes in Painleve'-Gullstrand coordinates with time-dependent mass parameter. We discuss the constraints on these models and their relation to the dynamical horizon paradigm. [Preview Abstract] |
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