The Limits of Quintessence

We present evidence that the simplest particle-physics scalar-field models of dynamical dark energy can be separated into distinct behaviors based on the acceleration or deceleration of the field as it evolves down its potential towards a zero minimum. We show that these models occupy narrow regions in the phase-plane of w and w', the dark energy equation-of-state and its time-derivative in units of the Hubble time. Restricting an energy scale of the dark energy microphysics limits how closely a scalar field can resemble a cosmological constant. These results, indicating a desired measurement resolution of order \sigma(w')\approx (1+w), define firm targets for observational tests of the physics of dark energy.Comment: 4 pages, 2 figure

Experiment to evaluate feasibility of utilizing Skylab-EREP remote sensing data for tectonic analysis of the Bighorn Mountains region, Wyoming-Montana

There are no author-identified significant results in this report

Study of guidance techniques for aerial application of agricultural compounds

Candidate systems were identified for evaluation of suitability in meeting specified accuracy requirements for a swath guidance system in an agriculture aircraft. Further examination reduced the list of potential candidates to a single category, i.e., transponder type systems, for detailed evaluation. Within this category three systems were found which met the basic accuracy requirements of the work statement. The Flying Flagman, the Electronic Flagging and the Raydist Director System. In addition to evaluating the systems against the specified requirements, each system was compared with the other two systems on a relative basis. The conclusions supported by the analyses show the Flying Flagman system to be the most suitable system currently available to meet the requirements

Large-Scale Bulk Motions Complicate the Hubble Diagram

We investigate the extent to which correlated distortions of the luminosity distance-redshift relation due to large-scale bulk flows limit the precision with which cosmological parameters can be measured. In particular, peculiar velocities of type 1a supernovae at low redshifts may prevent a sufficient calibration of the Hubble diagram necessary to measure the dark energy equation of state to better than 10%, and diminish the resolution of the equation of state time-derivative projected for planned surveys. We consider similar distortions of the angular-diameter distance, as well as the Hubble constant. We show that the measurement of correlations in the large-scale bulk flow at low redshifts using these distance indicators may be possible with a cumulative signal-to-noise ratio of order 7 in a survey of 300 type 1a supernovae spread over 20,000 square degrees.Comment: 6 pages; 4 figure

General Slow-Roll Spectrum for Gravitational Waves

We derive the power spectrum P_\psi(k) of the gravitational waves produced during general classes of inflation with second order corrections. Using this result, we also derive the spectrum and the spectral index in the standard slow-roll approximation with new higher order corrections.Comment: 8 pages, no figure ; Discussion slightly expanded and minor typos correcte

Exact Perturbations for inflation with smooth exit

Toy models for the Hubble rate or the scalar field potential have been used to analyze the amplification of scalar perturbations through a smooth transition from inflation to the radiation era. We use a Hubble rate that arises consistently from a decaying vacuum cosmology, which evolves smoothly from nearly de Sitter inflation to radiation domination. We find exact solutions for super-horizon perturbations (scalar and tensor), and for sub-horizon perturbations in the vacuum- and radiation-dominated eras. The standard conserved quantity for super-horizon scalar perturbations is exactly constant for growing modes, and zero for the decaying modes.Comment: Minor errors correcte

Non-Gaussianity from Self-Ordering Scalar Fields

The Universe may harbor relics of the post-inflationary epoch in the form of a network of self-ordered scalar fields. Such fossils, while consistent with current cosmological data at trace levels, may leave too weak an imprint on the cosmic microwave background and the large-scale distribution of matter to allow for direct detection. The non-Gaussian statistics of the density perturbations induced by these fields, however, permit a direct means to probe for these relics. Here we calculate the bispectrum that arises in models of self-ordered scalar fields. We find a compact analytic expression for the bispectrum, evaluate it numerically, and provide a simple approximation that may be useful for data analysis. The bispectrum is largest for triangles that are aligned (have edges $k_1\simeq 2 k_2 \simeq 2 k_3$) as opposed to the local-model bispectrum, which peaks for squeezed triangles ($k_1\simeq k_2 \gg k_3$), and the equilateral bispectrum, which peaks at $k_1\simeq k_2 \simeq k_3$. We estimate that this non-Gaussianity should be detectable by the Planck satellite if the contribution from self-ordering scalar fields to primordial perturbations is near the current upper limit.Comment: 11 pages, 1 figur

Cosmic Shear of the Microwave Background: The Curl Diagnostic

Weak-lensing distortions of the cosmic-microwave-background (CMB) temperature and polarization patterns can reveal important clues to the intervening large-scale structure. The effect of lensing is to deflect the primary temperature and polarization signal to slightly different locations on the sky. Deflections due to density fluctuations, gradient-type for the gradient of the projected gravitational potential, give a direct measure of the mass distribution. Curl-type deflections can be induced by, for example, a primordial background of gravitational waves from inflation or by second-order effects related to lensing by density perturbations. Whereas gradient-type deflections are expected to dominate, we show that curl-type deflections can provide a useful test of systematics and serve to indicate the presence of confusing secondary and foreground non-Gaussian signals.Comment: 8 pages, 3 figures; PRD submitte