784 research outputs found

    A new model for the infrared emission of IRAS F10214+4724

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    We present a new model for the infrared emission of the high redshift hyperluminous infrared galaxy IRAS F10214+4724 which takes into account recent photometric data from Spitzer and Herschel that sample the peak of its spectral energy distribution. We first demonstrate that the combination of the AGN tapered disc and starburst models of Efstathiou and coworkers, while able to give an excellent fit to the average spectrum of type 2 AGN measured by Spitzer, fails to match the spectral energy distribution of IRAS F10214+4724. This is mainly due to the fact that the nuSnu distribution of the galaxy falls very steeply with increasing frequency (a characteristic of heavy absorption by dust) but shows a silicate feature in emission. We propose a model that assumes two components of emission: clouds that are associated with the narrow-line region and a highly obscured starburst. The emission from the clouds must suffer significantly stronger gravitational lensing compared to the emission from the torus to explain the observed spectral energy distribution.Comment: 4 pages, 1 figure, to be published in 'The Spectral Energy Distribution of Galaxies' J. Tuffs \& C.C.Popescu, ed

    The Radio-to-Submillimeter Flux Density Ratio of Galaxies as a Measure of Redshift

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    We re-examine the technique of determining the redshifts of galaxies from the ratio of the submillimeter-to-radio continuum flux densities based on a recently published catalog of 850~μ\mum sources. We derived the expected variation of this ratio as a function of redshift incorporating the expected average luminosity and the spectral energy distribution (SED) of dust emission and the radio continuum. We find that the existing data for most of the high redshift (z \gtsim 1) sources correspond to our new calculation. Amongst the well-identified sources, there is none with an index significantly higher than predicted. Sources which have an index lower than predicted are either within the error zone or much lower, the latter presumably having AGN-dominated radio-continuum emission. We find the median redshift to be 2\sim 2, which is consistent with that deduced by previous work (3\sim 3) within the error. We also discuss the various systematic effects that can affect the accuracy of the redshift estimate. We examine other methods of redshift estimation, like photometric ratio in the submillimeter and locating the peak of the SED in the rest system of the objects. We conclude that while the various methods are helpful in identifying high-redshift objects and making a crude estimate of the redshift, they are not, at present, accurate enough for a detailed study of redshift distribution of the submillimeter galaxies.Comment: 6 pages LaTeX, PASJ in pres

    The influence of storing high moisture-content rough rice on milling quality

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    The objective of this research was to determine the influence on drying characteristics of storing high-moisture content (MC) rough rice under various conditions and durations before drying. Two cultivars of rice, \u27Bengal\u27, a medium-grain cultivar, and \u27Cypress\u27, a long-grain cultivar, were used. The MC of \u27Bengal\u27 was 24.8%1 and that of \u27Cypress\u27 was 20.4% at harvest. Immediately after harvest, drying runs were performed with samples of both cultivars under two drying air conditions: one at 51.7°C (125°F) and 25% relative humidity (RH), and the other at 60°C (140°F) and 17% RH. Storage treatments using the high MC rice were also initiated immediately after harvest. Both cultivars of rough rice were stored for one month (i.e., 27 d) and three months (i.e., 76 d) in either a walkin freezer at –9°C (15°F), a household refrigerator at 3.5°C (38.3°F) or a walk-in cooler at 4°C (38.5°F). After one month and three months of storage, all samples were dried under the same two drying air conditions as at harvest. The head rice yield (HRY) was determined for all the dried samples. There were no differences in the HRYs of samples that were stored for one or three months and then dried and in those HRYs of samples dried immediately after harvest; this finding was consistent across the three storage temperatures for both cultivars. The trends in HRY reduction were similar to previously reported drying trials using these drying air conditions. This research indicates that it is possible to store rough rice at high MCs for up to three months under storage temperatures varying from –9°C to 4°C without affecting HRY

    CBERN-NNK Knowledge Needs Research Summary:Report to the CBERN/Naskapi Steering Committee and the Naskapi Community

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    This report has been prepared for the Naskapi Steering Committee and the Naskapi community by Peter Siebenmorgen Research Assistantand Dr. Wesley Cragg, Project Director. The Canadian Business Ethics Research Network (CBERN) has been working in collaboration with the Naskapi Nation of Kawawachikamach (NNK) since early 2007. This relationship was initiated by former NNK Chief Phil Einish. The goal has been to ensure that the Naskapi people benefitted from mining on their traditional territories and avoided the negative impacts caused by previous mining activity by the Iron Ore Company of Canada. Working with Naskapi leadership, Dr. Cragg and Dr. Bradshaw developed a plan to identify community concerns and hopes for mining development on their traditional territory and provide access to the information and knowledge the community needed to address those concerns and hopes. The goal is to provide the community with the information it requires to benefit from development now taking place.The first step in the plan has now been completed. This report to the Naskapi community describes what the research team found.The second part of the plan is to improve access to information that will help the community address its concerns and realize its hopes for building a better and stronger future

    PAHs in protoplanetary disks: emission and X-ray destruction

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    We study the PAH emission from protoplanetary disks. First, we discuss the dependence of the PAH band ratios on the hardness of the absorbed photons and the temperature of the stars. We show that the photon energy together with a varying degree of the PAH hydrogenation accounts for most of the observed PAH band ratios without the need to change the ionization degree of the molecules. We present an accurate treatment of stochastic heated grains in a vectorized three dimensional Monte Carlo dust radiative transfer code. The program is verified against results using ray tracing techniques. Disk models are presented for T Tauri and Herbig Ae stars. Particular attention is given to the photo-dissociation of the molecules. We consider beside PAH destruction also the survival of the molecules by vertical mixing within the disk. By applying typical X-ray luminosities the model accounts for the low PAH detection probability observed in T Tauri and the high PAH detection statistics found in Herbig Ae disks. Spherical halos above the disks are considered. We show that halos reduce the observed PAH band-to-continuum ratios when observed at high inclination. Finally, mid-IR images of disks around Herbig Ae disks are presented. We show that they are easier to resolve when PAH emission dominate.Comment: Accepted for publication in A&A. 10 pages, 7 figures, 2 tabl