The PSCz Galaxy Power Spectrum Compared to N-Body Simulations

By comparing the PSCz galaxy power spectrum with haloes from nested and phased N-body simulations, we try to understand how IRAS infrared-selected galaxies populate dark-matter haloes. We pay special attention to the way we identify haloes in the simulations.Comment: 2 pages, 1 figure, to appear in "The IGM/Galaxy Connection: The Distribution of Baryons at z=0," eds. J.L. Rosenberg and M.E. Putma

PILOT: design and capabilities

The proposed design for PILOT is a general-purpose, wide-field 1 degree 2.4m, f/10 Ritchey-Chretien telescope, with fast tip-tilt guiding, for use 0.5-25 microns. The design allows both wide-field and diffraction-limited use at these wavelengths. The expected overall image quality, including median seeing, is 0.28-0.3" FWHM from 0.8-2.4 microns. Point source sensitivities are estimated.Comment: 4 pages, Proceedings of 2nd ARENA conference 'The Astrophysical Science Cases at Dome C', Potsdam, 17-21 September 200

The energy efficient engine project

The Energy Efficient Engine Project is directed at providing, by 1984, the advanced technologies which could be used for a generation of fuel conservative turbofan engines. The project is conducted through contracts with the General Electric Company and Pratt and Whitney Aircraft. The scope of the entire project and the current status of these efforts are summarized. A description of the preliminary designs of the fully developed engines is included and the potential benefits of these advanced engines, as well as highlights of some of the component technology efforts conducted to date, are discussed

Luminosity Density of Galaxies and Cosmic Star Formation Rate from Lambda-CDM Hydrodynamical Simulations

We compute the cosmic star formation rate (SFR) and the rest-frame comoving luminosity density in various pass-bands as a function of redshift using large-scale \Lambda-CDM hydrodynamical simulations with the aim of understanding their behavior as a function of redshift. To calculate the luminosity density of galaxies, we use an updated isochrone synthesis model which takes metallicity variations into account. The computed SFR and the UV-luminosity density have a steep rise from z=0 to 1, a moderate plateau between z=1 - 3, and a gradual decrease beyond z=3. The raw calculated results are significantly above the observed luminosity density, which can be explained either by dust extinction or the possibly inappropriate input parameters of the simulation. We model the dust extinction by introducing a parameter f; the fraction of the total stellar luminosity (not galaxy population) that is heavily obscured and thus only appears in the far-infrared to sub-millimeter wavelength range. When we correct our input parameters, and apply dust extinction with f=0.65, the resulting luminosity density fits various observations reasonably well, including the present stellar mass density, the local B-band galaxy luminosity density, and the FIR-to-submm extragalactic background. Our result is consistent with the picture that \sim 2/3 of the total stellar emission is heavily obscured by dust and observed only in the FIR. The rest of the emission is only moderately obscured which can be observed in the optical to near-IR wavelength range. We also argue that the steep falloff of the SFR from z=1 to 0 is partly due to the shock-heating of the universe at late times, which produces gas which is too hot to easily condense into star-forming regions.Comment: 25 pages, 6 figures. Accepted version in ApJ. Substantially revised from the previous version. More emphasis on the comparison with various observations and the hidden star formation by dust extinctio

Increased Mach Number Capability for the NASA Glenn 10x10 Supersonic Wind Tunnel

Computational simulations and wind tunnel testing were conducted to explore the operation of the Abe Silverstein Supersonic Wind Tunnel at the NASA Glenn Research Center at test section Mach numbers above the current limit of Mach 3.5. An increased Mach number would enhance the capability for testing of supersonic and hypersonic propulsion systems. The focus of the explorations was on understanding the flow within the second throat of the tunnel, which is downstream of the test section and is where the supersonic flow decelerates to subsonic flow. Methods of computational fluid dynamics (CFD) were applied to provide details of the shock boundary layer structure and to estimate losses in total pressure. The CFD simulations indicated that the tunnel could be operated up to Mach 4.0 if the minimum width of the second throat was made smaller than that used for previous operation of the tunnel. Wind tunnel testing was able to confirm such operation of the tunnel at Mach 3.6 and 3.7 before a hydraulic failure caused a stop to the testing. CFD simulations performed after the wind tunnel testing showed good agreement with test data consisting of static pressures along the ceiling of the second throat. The CFD analyses showed increased shockwave boundary layer interactions, which was also observed as increased unsteadiness of dynamic pressures collected in the wind tunnel testing

Clustering of the Diffuse Infrared Light from the COBE DIRBE maps. III. Power spectrum analysis and excess isotropic component of fluctuations

The cosmic infrared background (CIB) radiation is the cosmic repository for energy release throughout the history of the universe. Using the all-sky data from the COBE DIRBE instrument at wavelengths 1.25 - 100 mic we attempt to measure the CIB fluctuations. In the near-IR, foreground emission is dominated by small scale structure due to stars in the Galaxy. There we find a strong correlation between the amplitude of the fluctuations and Galactic latitude after removing bright foreground stars. Using data outside the Galactic plane ($|b| > 20\deg$) and away from the center ($90\deg< l <270\deg$) we extrapolate the amplitude of the fluctuations to cosec$|b|=0$. We find a positive intercept of $\delta F_{\rm rms} = 15.5^{+3.7}_{-7.0},5.9^{+1.6}_{-3.7}, 2.4^{+0.5}_{-0.9}, 2.0^{+0.25}_{-0.5}$ nW/m2/sr at 1.25, 2.2,3.5 and 4.9 mic respectively, where the errors are the range of 92% confidence limits. For color subtracted maps between band 1 and 2 we find the isotropic part of the fluctuations at $7.6^{+1.2}_{-2.4}$ nW/m2/sr. Based on detailed numerical and analytic models, this residual is not likely to originate from the Galaxy, our clipping algorithm, or instrumental noise. We demonstrate that the residuals from the fit used in the extrapolation are distributed isotropically and suggest that this extra variance may result from structure in the CIB. For 2\deg< \theta < 15^\deg, a power-spectrum analysis yields firm upper limits of (\theta/5^\deg) \times\delta F_{\rm rms} (\theta) < 6, 2.5, 0.8, 0.5 nW/m2/sr at 1.25, 2.2, 3.5 and 4.9 mic respectively. From 10-100 mic, the upper limits <1 nW/m2/sr.Comment: Ap.J., in press. 69 pages including 24 fig

The Role of State and Local Government in the Economic Development of Appalachia

One dimension of development planning for Appalachia which has been given little attention is the potential role of state and local governments. That is, what taxation and expenditure policies are most harmonious with the goals of economic development? The dual objectives of this paper are to examine the trend and pattern of finances shaped by the state and local government sector in an underdeveloped Appalachian state, and to explore the implications of alternative public (state- local) policies for economic growth