Bulletin of the American Physical Society
2007 APS Four Corners Section/SPS Zone 16 Joint Fall Meeting
Volume 52, Number 14
Friday–Saturday, October 19–20, 2007; Flagstaff, Arizona
Session K3: Astro: Stars to Extragalactic |
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Chair: Kathy Eastwood, Northern Arizona University Room: Chemistry (Bldg. 20) Room 233 |
Saturday, October 20, 2007 2:00PM - 2:12PM |
K3.00001: Development of a Method for Calculating Delta Scuti Rotational Velocities and Hydrogen-Beta Color Indices Tabitha Bush, Eric Hintz To add to the understanding of the structure and evolution of Delta Scuti stars, 167 delta Scutis north of -01 degrees declination and brighter than 13th magnitude have been observed spectroscopically. A method for calculating rotational velocity values and hydrogen-beta color indices for the stars in the data set with no previously published values is developed, using the stars in the data set brighter than 7th magnitude. Rotational velocity values for four stars with previously unknown values and hydrogen-beta index values for five stars with previously unknown values are calculated. [Preview Abstract] |
Saturday, October 20, 2007 2:12PM - 2:24PM |
K3.00002: Detection of M87 with the VERITAS Observatory Gary Finnegan In the 2007 observing season, we performed observations of the elliptical galaxy M87, located at a distance of 16 Mpc (redshift z = 0.00436), with the VERITAS imaging air Cherenkov gamma-ray telescopes. This source has been previously detected by the HEGRA and HESS gamma-ray observatories. Using the GrISU set of standard analysis tools, we detect M87 with high significance during spring 2007. In this talk, I will describe the analysis of the data and the detection of this source. I will compare this detection with archival HEGRA and HESS light curves of M87. [Preview Abstract] |
Saturday, October 20, 2007 2:24PM - 2:36PM |
K3.00003: A Method for Predicting Quasar Luminosity Consistent With the NASA/IPAC Extragalactic Database Morris Anderson It is widely accepted that quasar radiation is emitted from a thick torus shaped accretion disk surrounding a black hole. However, the Chandra X-ray Observatory wide field panorama released on March 12, 2007, indicates many quasars do not have an accretion disk and cannot be explained by this representation. A solution is presented that does not require or exclude an accretion disk. It is based on the method first suggested in the 2004 APS Four Corners Section Fall Meeting presentation, ``Wave Propagation in a Gravitational Field.'' This model makes it possible to predict quasar luminosity as a function of gravitational redshift in qualitative agreement with the population distribution recorded in the NASA/IPAC Extragalactic Database. Furthermore, it indicates conditions may become critical at a redshift of 3.5 causing a quasar to ignite in a form of radiation limited gravitational collapse. These results offer a possible explanation for a peak, at a redshift of 3.75, in the observed population distribution. The success of this approach provides convincing evidence that gravity is the primary influence behind both the radiant power and redshift of quasars. [Preview Abstract] |
Saturday, October 20, 2007 2:36PM - 2:48PM |
K3.00004: Applying Several-Order Autocorrelation Functions To Obtain An Optical Crab Pulsar Light Curve Jose Cardoza The Crab Nebula was the first steady VHE gamma-ray emitter discovered, and has recently been detected by the VERITAS gamma ray observatory. The 33 millisecond-period Crab Pulsar, located at the center of the plerion, is a spinning neutron star that provides most of the power needed for the broad-band emission spectrum of the nebula. Periodic emission by the pulsar has never been reliably detected in VHE gamma rays. In this talk, I will describe the detection of the steady state VHE gamma ray emission from the nebula. I will also describe the application of autocorrelation functions of several orders to optical data as a first step towards developing a technique for detecting periodic emission from the pulsar. [Preview Abstract] |
Saturday, October 20, 2007 2:48PM - 3:00PM |
K3.00005: Neutrino and Gamma Ray Flux Expectations from HiRes Monocular Fits Olga Brusova, Douglas R. Bergman, Kai Martens A simple model of a homogeneous population of cosmic accelerators injecting protons following a unique power law has long been shown to fit the HiRes monocular data very well. The model evolves the sources with redshift and adjusts both the redshift evolution and the exponent in the injecting power law to fit the data. At lower energies galactic iron is added in as suggested by composition measurements. The model includes interactions between cosmic ray protons of extragalactic origin and photons of the cosmic microwave background radiation; in particular photopion production, which causes the GZK cutoff. We present neutrino and gamma ray fluxes derived from proton propagation given the fitted injection spectrum and redshift evolution of their extragalactic sources. [Preview Abstract] |
Saturday, October 20, 2007 3:00PM - 3:12PM |
K3.00006: VERITAS observation of High Energy Gamma-Ray Emission from H1426+428 Michael Newbold VHE emission from the extragalactic Bl Lac object H1426+428 (redshift of z = 0.129) was first reported by the Whipple 10m telescope collaboration in 2001. We have recently performed new observations of H1426+428 with the VERITAS imaging air-Cherenkov gamma-ray telescopes, located in southern Arizona at the Fred Lawrence Whipple Observatory. Between January to April 2007, we accumulated approximately 10 hours of observations on H1426+428. In this talk, I will describe the observations and the analysis of the data using the standard GrISU analysis package, and I will compare these results to previous detections of 1H1426+428. [Preview Abstract] |
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