Analysis of pressure-broadened ozone spectra in the 3 micron region

This work involves the analysis of a series of McMath Fourier Transform Infrared (FTIR) spectra of ozone broadened by mixing with air (four different pressures), nitrogen (three pressures), or oxygen (three pressures). Each spectrum covers the region from 2396 to 4057 cm(-1). This study focused on the 3 sub nu sub 3 band in t 3000 to 3060 cm(-1). The band is analyzed by first dividing its region into small intervals containing a few well isolated absorption lines of reasonable intensity. Each of these small intervals is fit by multiple iterations of the nonlinear least squares program until residuals (the difference between calculated and observed spectrum, as a percent of the strongest intensity in the interval) are minimized to a reasonable value which corresponds to the noise level of the measured spectrum. Position, intensity, and half-width are recorded for later analysis. From the measured half-widths, a pressure broadening coefficient was determined for each absorption line. Pressure shifts were determined by comparing observed line positions in the spectra of the diluted ozone samples to tabulated line positions determined from spectra of pure gas samples. Comparisons to other work on ozone indicate that the broadening and shift coefficients determined in this study are consistent with those determined in other spectral regions

MAXIMUM ECONOMIC YIELD AND RESOURCE ALLOCATION IN THE SPINY LOBSTER INDUSTRY

Resource /Energy Economics and Policy,

Metal abundances and ionization conditions in a possibly dust-free damped Ly-alpha system at z=2.3

We have obtained a high resolution, high S/N UVES spectrum of the bright QSO HE2243-6031 to analyze the damped Ly-alpha system (DLA) observed at z=2.33. The metallicity of this system is 1/12 solar at a neutral hydrogen column density of log N(HI)=20.7. From the observed ratios [Zn/Cr]=-0.01+/-0.05 and [S/Si]=-0.06+/-0.03$ we conclude that dust is very likely absent from the ISM of this protogalaxy. We observe an enhancement of the alpha/Fe-peak ratios of +0.2 dex for various elements, a marked odd-even effect in Mn, and a strong underabundance of N relative to Si and S, [N/Si,S]=-1 at [Si/H]=-0.86. All of these ratios support an environment that is in an early evolutionary stage, where the onset of star formation has begun only shortly before the DLA was observed. We also perform a cloud-by-cloud analysis -- without precedent at high redshift -- and find a tight correlation of all low-ionization species with respect to FeII extending over 2.5 orders of magnitude in N(FeII). We interpret this trend as being due to homogeneous physical conditions (very mild ionization effects, common dust-destruction histories, same chemical composition) and propose that this line of sight encounters absorbing clouds that share a common environment. In addition, photoionization models show that these single clouds are shielded from the external ionizing radiation, so the fraction of ionized gas is small and, except for argon, does not influence the measured metal abundances. The observed AlIII/low-ion ratios suggest the mildly ionized gas occurs in shells surrounding neutral cores of AlII.Comment: To be published in A&

Damped Lyman alpha systems and galaxy formation models - II. High ions and Lyman limit systems

We investigate a model for the high-ionization state gas associated with observed damped Lyman-alpha systems, based on a semi-analytic model of galaxy formation set within the paradigm of hierarchical structure formation. In our model, the hot gas in halos and sub-halos gives rise to CIV absorption, while the low-ionization state gas is associated with the cold gas in galaxies. The model matches the distribution of CIV column densities and leads naturally to kinematic properties that are in good agreement with the data. We examine the contribution of both hot and cold gas to sub-damped systems and suggest that the properties of these systems can be used as an important test of the model. We expect that sub-DLA systems will generally be composed of a single gas disk and thus predict that they should have markedly different kinematics than the damped systems. Finally, we find that hot halo gas produces less than one third of Lyman limit systems at redshift three. We model the contribution of mini-halos (halos with virial velocities < 35 km/s) to Lyman limit systems and find that they may contain as much gas as is observed in these systems. However, if we adopt realistic models of the gas density distribution we find that these systems are not a significant source of Lyman limit absorption. Instead we suggest that uncollapsed gas outside of virialized halos is responsible for most of the Lyman limit systems at high redshift.Comment: 12 pages, 8 figures, submitted to MNRA

Metallicities, dust and molecular content of a QSO-Damped Lyman-{\alpha} system reaching log N (H i) = 22: An analog to GRB-DLAs

We present the elemental abundance and H2 content measurements of a Damped Lyman-{\alpha} (DLA) system with an extremely large H i column density, log N(H i) (cm-2) = 22.0+/-0.10, at zabs = 3.287 towards the QSO SDSS J 081634+144612. We measure column densities of H2, C i, C i^*, Zn ii, Fe ii, Cr ii, Ni ii and Si ii from a high signal-to-noise and high spectral resolution VLT-UVES spectrum. The overall metallicity of the system is [Zn/H] = -1.10 +/- 0.10 relative to solar. Two molecular hydrogen absorption components are seen at z = 3.28667 and 3.28742 (a velocity separation of \approx 52 km s-1) in rotational levels up to J = 3. We derive a total H2 column density of log N(H2) (cm-2) = 18.66 and a mean molecular fraction of f = 2N(H2)/[2N(H2) + N(H i)] = 10-3.04+/-0.37, typical of known H2-bearing DLA systems. From the observed abundance ratios we conclude that dust is present in the Interstellar Medium (ISM) of this galaxy, with a enhanced abundance in the H2-bearing clouds. However, the total amount of dust along the line of sight is not large and does not produce any significant reddening of the background QSO. The physical conditions in the H2-bearing clouds are constrained directly from the column densities of H2 in different rotational levels, C i and C i^* . The kinetic temperature is found to be T = 75 K and the particle density lies in the range nH = 50-80 cm-3 . The neutral hydrogen column density of this DLA is similar to the mean H i column density of DLAs observed at the redshift of {\gamma}-ray bursts (GRBs). We explore the relationship between GRB-DLAs and high column density end of QSO-DLAs finding that the properties (metallicity and depletion) of DLAs with log N(H i) > 21.5 in the two populations do not appear to be significantly different