Bulletin of the American Physical Society
74th Annual Meeting of the Southeastern Section
Volume 52, Number 13
Thursday–Saturday, November 8–10, 2007; Nashville, Tennessee
Session GB: Astronomy/Gravity |
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Chair: Oyekale Oyedeji, Morehouse College Room: Scarritt-Bennett Center Laskey B |
Friday, November 9, 2007 8:30AM - 8:42AM |
GB.00001: Gravitational waves, and what they can tell us about the Universe Lior M. Burko Our understanding of gravitational waves has increased dramatically since Eddington wrote in 1922 that some believe they ``propagate with the speed of thought.'' While gravitational waves are yet to be directly detected ---ignoring the orbital decay of the Hulse--Taylor binary pulsar as an {\em indirect} measurement--- an impressive experimental effort to detect them has defied many skeptics when LIGO achieved design sensitivity. At the same time, several numerical relativity groups have succeeded in solving the ``holy grail'' problem: evolve a binary black hole system for a number of orbits, following the system through its merger to its final ring--down and decay to quiescence, thus predicting the gravitational waveforms that LIGO, and other experiments, will detect. In this talk I will briefly describe the breathtaking progress we have witnessed, and what the future may hold for gravitational-wave astronomy. [Preview Abstract] |
Friday, November 9, 2007 8:42AM - 8:54AM |
GB.00002: Black hole quasi-normal mode spectroscopy with LISA Manish M. Jadhav, Lior M. Burko We present an improved estimate of the signal-to-noise ratio (SNR) from the ring-down phase of coalescing equal mass black hole binaries for the NASA/ESA space-borne interferometer LISA (Laser Interferometer Space Antenna). The usual angle-averaged expressions of spin-weighted spheroidal harmonics have been replaced by Monte-Carlo expressions, computed from randomly generated angles for detector--source directions and black hole orientations. For a given ``radiation efficiency" $\epsilon_{\rm rd}$, we use randomly generated ``radiation efficiency per polarization" $\epsilon^{+,\times}$ to estimate the non-angle-averaged, polarization- phase-dependent SNR for Schwarzschild and Kerr black holes. [Preview Abstract] |
Friday, November 9, 2007 8:54AM - 9:06AM |
GB.00003: Estimating the frequency-domain computation time of extreme mass-ratio inspiral gravitational waveforms David J. Lazar, Lior M. Burko We estimate the overall computation time for the frequency-domain calculation of gravitational-wave energy fluxes to infinity for extreme-mass-ratio inspiral binaries consisting of a compact object in orbit around a supermassive black hole on the latter's equatorial plane - an interesting source for LISA. We determine the number of $k$ modes necessary to achieve a desired accuracy for orbits of varying eccentricity. We then model the time required to calculate single $k$ modes and use this model to find the time it takes to sum over all the $k$ modes for a given accuracy level. Work to obtain models that also incorporate summing over multiple $m$ and $\ell$ modes is currently in progress. Our main goal is to eventually use our data to determine for what part of the parameter space the time-domain approach becomes more computationally efficient than the frequency-domain method. [Preview Abstract] |
Friday, November 9, 2007 9:06AM - 9:18AM |
GB.00004: The late-time tails in the Reissner-Nordstr\"{o}m spacetime revisited Carl J. Blaksley, Lior M. Burko The late-time tail problem in the Reissner-Nordstr\"{o}m (RN) spacetime is dual to a tail problem in the Schwarzschild spacetime with a different initial data set: At a fixed observation point the asymptotic decay rate of the fields are equal. This duality is used to find the decay rate for tails in RN. This decay rate is exactly as in Schwarzschild, including the case of the extremely-charged RN spacetime (ERN). The only case where any deviation from the Schwarzschild decay rate is found is the case of the tails along the event horizon of an ERN spacetime, where the decay rate is the same as at future null infinity. As observed at a fixed location, the decay rate in ERN is the same as in Schwarzschild. We verify these results with numerical simulations. [Preview Abstract] |
Friday, November 9, 2007 9:18AM - 9:30AM |
GB.00005: Simulations of the Sagittarius Dwarf Galaxy Collision with the Milky Way Jeannette Myers, Bart Snyder, Mary Rusthoven, Lih-Sin The, Dieter Hartmann The Sagittarius Dwarf Galaxy is one of the satellite galaxies interacting with the Milky Way. Discovered to be located just below the galactic center; this galaxy is currently being tidally disrupted as it approaches the Milky Way disk. We performed a series of N-body/SPH simulations of the interaction between Sagittarius and the Milky Way over a 1 Gyr time period leading up to today's position. These simulations include an updated Milky Way model, gas and star formation. We highlight the creation of the tidal tails and compare them to the known tidal structures we observe today. [Preview Abstract] |
Friday, November 9, 2007 9:30AM - 9:42AM |
GB.00006: A Third-Order Differential Equation Modelling Stellar Pulsation Ronald Mickens, 'Kale Oyedeji, Anthony Afuwape We investigate the properties of the solutions to a third-order nonlinear ODE modeling the radial oscillations of a star. A summary of previous work on this equation has been presented by Cox [1]. Their calculations are based on the use of a two-time perturbation method to determine the possible existence and stability of limit-cycles. We demonstrate that the application of phase-space techniques and the Hopf bifurcation theorem gives results that differ from those reported by Cox. [1] J. P. Cox, Theory of Stellar Pulsation (Princeton University Press, 980), section 13.4. [Preview Abstract] |
Friday, November 9, 2007 9:42AM - 9:54AM |
GB.00007: An Accelerating Universe Around A Blackhole Abdul L. Choudhury, Harunar Rashid, Arshad Momen We assume the creation of a blackhole[1] in a physical universe. We now conjecture that the blackhole will then separate itself from the physical universe and build up an extra dimensional entity associated with the physical universe. We postulate this extra dimensional entity is to be orthogonal to the physical universe. We further conjecture that the blackhole is a Schwartzschild blackhole. We assume also that this physical universe and the blackhole together span a seven dimensional space with a common time coordinate. We then generate the Einstein equation. Using the time-blackhole-radial and the time time components of the equation we show that the Hubble parameter is positive and time dependent if we conjecture that both the scale factor and the radius of the blackhole reduce exponentially. Under the same assumption we also calculate the deacceleration parameter and show that under certain constraint on the parameters the universe accelerates. [1] arXiv:gr-qc/0608094 v1 20 Aug 2006. [Preview Abstract] |
Friday, November 9, 2007 9:54AM - 10:06AM |
GB.00008: Quasi-normal modes of a black hole localized on a brane Usama al-Binni, George Siopsis Black holes residing on a brane are expected to be observed at the LHC pointing to the existence of large extra dimensions. Signatures include the spectrum of Hawking radiation and quasi-normal modes through the detection of decay products. We calculate analytically the quasi-normal modes of black holes at the LHC using the WKB approximation. Unlike previous calculations, where the tension of the brane was assumed to be negligible, we obtain analytic expressions which are valid for any value of the tension of the brane (low as well as high). [Preview Abstract] |
Friday, November 9, 2007 10:06AM - 10:18AM |
GB.00009: Quasi-normal modes of AdS black holes and RHIC George Siopsis I calculate analytically low frequency quasi-normal modes of gravitational perturbations of AdS Schwarzschild black holes. I arrive at analytic expressions which are in agreement with their counterparts from linearized hydrodynamics, in accordance with the AdS/CFT correspondence. The results are also in good agreement with results of numerical calculations. I discuss their relevance to the quark-gluon plasma formed in heavy ion collisions at RHIC. [Preview Abstract] |
Friday, November 9, 2007 10:18AM - 10:30AM |
GB.00010: Black Holes versus Supersymmetry at the LHC Arunava Roy, Marco Cavaglia Supersymmetry and extra dimensions are the two most promising candidates for new physics at the TeV scale. Supersymmetric particles or extra-dimensional effects could soon be observed at the Large Hadron Collider. In this paper we assess the distinguishability of supersymmetry and black hole events at the LHC. Black hole events are simulated with the CATFISH black hole generator. Supersymmetry simulations use a combination of PYTHIA and ISAJET, the latter providing the mass spectrum. Our analysis shows that supersymmetry and black hole events at the Large Hadron Collider can be easily discriminated. [Preview Abstract] |
Friday, November 9, 2007 10:30AM - 10:42AM |
GB.00011: AdS/CFT Correspondence and Heavy Ion Collisions James Alsup, George Siopsis, Chad Middleton We study an extension of the gravity dual to a perfect fluid model found by Janik and Peschanski. By relaxing one of the constraints, namely invariance under reflection in the longitudinal direction, we introduce a metric ansatz which includes off-diagonal terms. We also include an R-charge following Bak and Janik. We solve the Maxwell-Einstein equations and through holographic renormalization, we show that the off-diagonal components of the bulk metric give rise to heat conduction in the corresponding CFT on the boundary. Our results might be relevant to understanding experimental results at heavy ion colliders such as RHIC. [Preview Abstract] |
Friday, November 9, 2007 10:42AM - 10:54AM |
GB.00012: Brane world mass unification of quarks and leptons Mehrdad Adibzadeh, P.Q. Hung We present a scenario combining a model of early (TeV-scale) unification of quarks and leptons with the physics of large extra dimensions, which provides a natural mechanism linking quark and lepton masses at TeV scales. In demonstrating ``quark-lepton mass unification'' within our model, we make use of the mechanism of wave function overlap along the large extra dimension. The mechanism connects the strengths of fermionic mass terms in four dimensions, as ``effective'' Yukawa couplings, to the magnitudes of overlaps between the wave functions of left- and right-handed fermions along a compact spatial dimension. The geometry of localized fermions in the extra dimension, which is determinant of such ``mass unification,'' is set by symmetry breakings. As a result, the TeV-scale quark-lepton symmetry structure translates into an early mass relation between quarks and leptons with implications on the mass of Dirac neutrino. [Preview Abstract] |
Friday, November 9, 2007 10:54AM - 11:06AM |
GB.00013: Proposed operator description of four dimensional Euclidean quantum gravity Jens Koeplinger This talk will give a brief overview over an algebraic system proposed for first quantization, operator description of (four dimensional) Euclidean quantum gravity. While the approach in general is well supported in field theory [e.g. G. W. Gibbons, S. W. Hawking (ed): Euclidean Quantum Gravity. Singapore: World Scientific (1993)], existence of an operator-based pendant is generally presumed unlikely at best. With use of a non- associative, 16-dimensional algebra (conic sedenions, or complex octonions) a formulation of the Dirac equation with electromagnetic field can be obtained, and subsequently rotated from Minkowskian to Euclidean space-time. An overview over support for such approach to describe quantum gravity will be given. Suggestions for further investigation will be mentioned, together with the difficulty in predicting measurable effects from quantum gravity in general. [Preview Abstract] |
Friday, November 9, 2007 11:06AM - 11:18AM |
GB.00014: The mass, energy, space and time system theory Cao Dayong Things have their own mass, energy, space and time of themself (The MEST for short thereinafter). The MEST is material. In quantum mechanics, the quality of radiate wave mainly is quantum space-time while it's mass-energy is ancillary. It is called mass-energy theory of relativity and the space-time system; The nature of the macrosubstance is mainly mass-energy while space-time are ancillary. It is called space-time theory of relativity and the mass-energy system. Mass-energy are like the earth while space-time are like the heaven. An Nuclear of an atom is like the earth while the charge cloud (wave) of an atom is like the heaven. Macro is like the earth while micro is like the heaven. The system of the MEST of heaven and earth, which unites both macrophysics and microphysics. The black hole and dark matter-energy is the space-time system; The Star and planet is the mass-energy system. They is a big system of heaven and earth. Using the interaction principle of space-time (wave), research the black hole and dark matter-energy. Dark matter-energy background come from black hole.We can use it to produce the quantum microcosmics black hole, and then we can produce new spaceflight. The MEST computing is a real unalloyed information system and a natural logic system. It can be used to research the black hole and dark matter-energy. [Preview Abstract] |
Friday, November 9, 2007 11:18AM - 11:38AM |
GB.00015: The New Era in Gravitational Wave Searches Has Begun Warren Johnson The Laser Interferometer Gravitational wave Observatory (LIGO) has just finished taking data for its first long observing run at design sensitivity. It had a sensitivity that was one to two orders of magnitude better that the best previous searches. There is a full year of coincident data with 3 LIGO detectors, and 4 months of 4 detector coincident data, when the VIRGO interferometer agreed to join in a grand world-wide collaboration. Analysis of the new data is proceeding at a rapid pace, and we hope soon to learn if there is positive or negative evidence for waves at this new level of sensitivity. In any case, two stages of detector upgrades are underway or planned, and prospects seem bright for the eventual commencement of gravitational wave astronomy. [Preview Abstract] |
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