Bulletin of the American Physical Society
12th Annual Meeting of the Northwest Section of the APS
Volume 55, Number 6
Friday–Saturday, October 1–2, 2010; Walla Walla, Washington
Session H1: Astrophysics, Cosmology, and Gravity |
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Chair: Sukanta Bose, Washington State University Room: Science 151 |
Saturday, October 2, 2010 1:30PM - 2:06PM |
H1.00001: A Common Origin for Baryonic Visible Matter and Antibaryonic Dark Matter Invited Speaker: We present a novel mechanism, hylogenesis, for generating both the baryon and dark matter densities of the Universe. A new Dirac fermion X carrying a conserved baryon number charge couples to the Standard Model quarks as well as a GeV-scale hidden sector. CP-violating decays of X, produced non-thermally in low-temperature reheating, sequester antibaryon number in the hidden sector, thereby leaving a baryon excess in the visible sector. The antibaryonic hidden states are stable dark matter. A spectacular signature of this mechanism is the baryon-destroying inelastic scattering of dark matter that can annihilate baryons at appreciable rates relevant for nucleon decay searches. [Preview Abstract] |
Saturday, October 2, 2010 2:06PM - 2:18PM |
H1.00002: Gravitational Tests of Lorentz Symmetry Jay Tasson Tests of Lorentz symmetry provide a potential means of detecting new physics originating at the Planck scale. The effects of hypothetical violations of Lorentz symmetry in experiments performed at presently accessible energies are described by a test framework called the Standard-Model Extension (SME). In this talk, I will provide a summary of the SME and discuss recent work on gravitational tests. [Preview Abstract] |
Saturday, October 2, 2010 2:18PM - 2:30PM |
H1.00003: A Search for Non-Newtonian Gravity at the Human Scale Ricco Bonicalzi, Paul Boynton, Riley Newman, Michael Moore, Eric Berg Many attempts to unify gravity with the Standard Model entail a violation of the gravitational inverse-square law. A new null torsion-pendulum experiment, operating at the Battelle Gravitational Physics Laboratory on the DOE-Hanford site, looks for such a violation in the interaction between macroscopic bodies separated by approximately 10cm. Central to the design is the special configuration of the mass distributions of both the pendulum and source mass to provide high-sensitivity to the horizontal gradient of the Laplacian of the interaction potential (a uniquely non-Newtonian signature), while simultaneously suppressing coupling through Newtonian gravity. Recent progress will be reported. [Preview Abstract] |
Saturday, October 2, 2010 2:30PM - 2:42PM |
H1.00004: Space Mission Concept for a Nuclear-Powered Airplane for Saturn's Moon Titan Jason W. Barnes Saturn's large moon Titan is one of the most interesting places in the solar system. It's the only moon with a significant atmosphere. With a temperature of around 90K, the methane in that atmosphere plays the same role that water does in Earth's atmosphere. Titan has methane clouds, methane rainfall, methane rivers, and methane lakes and seas as seen by the Cassini spacecraft. Future Titan exploration will require a more aggressive vehicle in order to follow up on Cassini's discoveries. I will present the motivation and design for a robotic `drone' aircraft mission to Titan: AVIATR, the Aerial Vehicle for In situ and Airborne Titan Reconnaissance. This platform makes sense because with $4~\times$ Earth's air density and only $\frac{1}{7}$ its gravity, flying at Titan is easier than any place else in the solar system. From AVIATR we could acquire images and near-infrared spectroscopy of the surface, search for waves in liquids, and measure winds and atmospheric properties directly, which would dramatically advance our understanding of this enigmatic, frigid moon. [Preview Abstract] |
Saturday, October 2, 2010 2:42PM - 2:54PM |
H1.00005: Physics of the weird solar minimum: New observations of the Sun E. Zita, C. Smith, C. Ballou, B. Friedman, C. Showalter, R. Rex, N. Hurlburt While solar physicists expected more sunspots, flares, and coronal mass ejections by now, the Sun has defied most predictions by persisting in a relatively quiet state for an unusually long time. Can we tell whether this solar minimum is likely to ease in the next decade, or if it may become a Maunder-type minimum? What evidence is there for mechanisms that might explain the observed delayed and low-amplitude magnetic activity? What effects could decreased solar activity have on Earth's climate? Evergreen undergraduates study the Sun with colleagues who built the new Solar Dynamics Observatory (SDO). Students analyzed flow velocities with respect to magnetic field tilts; analyzed waves of UV light in active regions; developed a software suite to enable the public to engage with solar dynamics; and cataloged movies of solar events for public release. We use data from the high-resolution HINODE satellite and from the new full-disk SDO. Zita studied the solar dynamo, and found that resistivity gradients can drive magnetic advection. We summarize our work and the light it may shed on questions such as those above. [Preview Abstract] |
Saturday, October 2, 2010 2:54PM - 3:06PM |
H1.00006: A null experiment shows that superluminal group velocity of tunneling photons is not superluminal energy flow because it is not sensitive to Earth's absolute motion George Soli A method for showing that superluminal group velocity, associated with tunneling photons, is not superluminal energy flow, is to measure possible preferred frame effects. In Lorentz invariant theories, causal superluminal energy propagation in one reference frame is acausal in other frames. But Lorentz-violating theories have a preferred frame in which causal evolution is defined and superluminal propagation becomes causal in all reference frames. Null measurements show that preferred frame effects do not exist relative to a CMB rest frame velocity of about 370 km/s. [Preview Abstract] |
Saturday, October 2, 2010 3:06PM - 3:20PM |
H1.00007: BREAK
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Saturday, October 2, 2010 3:20PM - 3:56PM |
H1.00008: Surveying the Sky with the Large Synoptic Survey Telescope Invited Speaker: The LSST is a wide-field survey telescope that will observe the optical sky from Cerro Pachon in Chile. With an 8.4m primary mirror and a 3.2 Gpixel camera the LSST will image about 20,000 sq degrees of the sky every three nights. The system is designed to produce well sampled images with extremely high astrometric and photometric accuracy across the six passbands ugrizy (covering 350-1050nm). For a ten year survey, returning to each pointing on the sky $>$ 1000 times, the final coadded depth of the LSST will be r~27.5 mag. In this talk I will describe the LSST system, its current status and how we expect to undertake science with a system that generates Petabytes of data per year. [Preview Abstract] |
Saturday, October 2, 2010 3:56PM - 4:08PM |
H1.00009: Toward improving the duty factor of GW interferometers Szymon Steplewski The LIGO detectors are being operated to discover gravitational waves from a variety of astrophysical sources in the universe. Their operation is dependent on being in a resonant condition known as ``lock,'' which can be broken by instrumental or environmental disturbances. I am working to identify the specific causes of these broken locks and trying to understand where potential improvements would be most useful in maintaining lock. Towards this goal I have been developing new instrumental monitors that will help researchers track down disruptions in the system. I am also working on software that attempts to categorize the disruptive events according to the source. Understanding these events will eventually allow longer periods of lock with less downtime. [Preview Abstract] |
Saturday, October 2, 2010 4:08PM - 4:20PM |
H1.00010: New results in black hole-neutron star merger models Matthew Duez I report on the SXS group's recent progress in using numerical general relativity to model one of the most violent and fascinating events in nature: the devouring of a neutron star by a black hole. I will discuss our efforts to simulate more representative and generic binary configurations and also our efforts to incorporate more realistic neutron star microphysics. Our numerical simulations allow us to predict post-merger states and gravitational wave signals. [Preview Abstract] |
Saturday, October 2, 2010 4:20PM - 4:32PM |
H1.00011: Searching for perturbed black-hole ringdown signals with a network of gravitational-wave detectors Dipongkar Talukder, Sukanta Bose Several ground-based interferometric observatories, such as LIGO, Virgo, are taking data so that astronomers can search for gravitational-wave signals in them. One such signal is that arising from a perturbed black-hole, which can result from the coalescence of a compact binary. This signal is initially in the form of a superposition of quasi-normal modes. However, at late times the waveform, which is known as ringdown, is expected to be dominated by a single mode. The optimal method for searching such a signal buried in detector noise is to match-filter the detector's output with theoretically modeled waveforms. The coherent network statistic is optimal for detecting these signals in Gaussian noise. But in real noise, which is non-Gaussian and non-stationary, additional discriminators of noise artifacts are required for obtaining a (near-)optimal statistic. Here, we construct a multi-detector search statistic that combines the power of the coherent statistic and those discriminators. The efficiency of this new search statistic is compared with the existing ``coincidence'' search statistic, which does not check for the consistency of the phase of the signal in the separate detectors. [Preview Abstract] |
Saturday, October 2, 2010 4:32PM - 4:44PM |
H1.00012: Gravitational Wave (GW) science in NINJA collaboration Thilina Dayanga, Sukanta Bose The Numerical INJection Analysis (NINJA) is a collaborative effort between members of the numerical relativity (NR) and GW data analysis communities. The purpose of NINJA project is to test the sensitivity of current gravitational wave searches using numerically generated Binary Black Hole (BBH) waveforms generated by different NR groups. The recent success in NR simulating the merger phase of the BBH coalescence helped NR community to construct more accurate waveforms for the BBH coalescence. NINJA-2 simulated data set was created injecting these full BBH waveforms. We coherently search for BBH signals in NINJA-2 data set using LIGO-VIRGO compact binary coalescence (CBC) multi-detector high-mass search pipeline. We report the efficiency of our search method and this will help us to search BBH signals in real multi-detector data. Coherent search is the optimal search method in Gaussian detector noise and NINJA-2 analysis will helpful to construct alternative methods to search in real data. [Preview Abstract] |
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