Scaling the Outdoor Environment

In this paper, we suggest a protocol for scaling the outdoor environment. This is based on total appearance techniques developed during a study of the food and drink indoor environment in which we related specific physical features to emotions and expectations generated in the viewer. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

Extreme UV QSOs

We present a sample of spectroscopically confirmed QSOs with FUV-NUV color (as measured by GALEX photometry) bluer than canonical QSO templates and than the majority of known QSOs. We analyze their FUV to NIR colors, luminosities and optical spectra. The sample includes a group of 150 objects at low redshift (z $<$ 0.5), and a group of 21 objects with redshift 1.7$<$z$<$2.6. For the low redshift objects, the "blue" FUV-NUV color may be caused by enhanced Ly$\alpha$ emission, since Ly$\alpha$ transits the GALEX FUV band from z=0.1 to z=0.47. Synthetic QSO templates constructed with Ly$\alpha$ up to 3 times stronger than in standard templates match the observed UV colors of our low redshift sample. The H$\alpha$ emission increases, and the optical spectra become bluer, with increasing absolute UV luminosity. The UV-blue QSOs at redshift about 2, where the GALEX bands sample restframe about 450-590A (FUV) and about 590-940A(NUV), are fainter than the average of UV-normal QSOs at similar redshift in NUV, while they have comparable luminosities in other bands. Therefore we speculate that their observed FUV-NUV color may be explained by a combination of steep flux rise towards short wavelengths and dust absorption below the Lyman limit, such as from small grains or crystalline carbon. The ratio of Ly$\alpha$ to CIV could be measured in 10 objects; it is higher (30% on average) than for UV-normal QSOs, and close to the value expected for shock or collisional ionization. FULL VERSION AVAILABLE FROM AUTHOR'S WEB SITE: http://dolomiti.pha.jhu.edu/papers/2009_AJ_Extreme_UV_QSOs.pdfComment: Astronomical Journal, in pres

A Lyman alpha halo around a quasar at redshift z=6.4

We present long-slit spectroscopic data which reveals extended Lyman alpha emission around the z=6.417 radio-quiet quasar CFHQS J2329-0301. The Lyman alpha emission is extended over 15 kpc and has a luminosity of > 8 x 10^36 W, comparable to the most luminous Lyman alpha halos known. The emission has complex kinematics, in part due to foreground absorption which only partly covers the extended nebula. The velocity ranges from -500 km/s to +500 km/s, with a peak remarkably close to the systemic velocity identified by broad MgII emission of the quasar. There is no evidence for infall or outflow of the halo gas. We speculate that the Lyman alpha emission mechanism is recombination after quasar photo-ionization of gas sitting within a high-mass dark matter halo. The immense Lyman alpha luminosity indicates a higher covering factor of cold gas compared to typical radio-quiet quasars at lower redshift.Comment: 7 pages, 7 figures, AJ, in pres

A search for the first massive galaxy clusters

We have obtained deep, multi-band imaging observations around three of the most distant known quasars at redshifts z>6. Standard accretion theory predicts that the supermassive black holes present in these quasars were formed at a very early epoch. If a correlation between black hole mass and dark matter halo mass is present at these early times, then these rare supermassive black holes will be located inside the most massive dark matter halos. These are therefore ideal locations to search for the first clusters of galaxies. We use the Lyman-break technique to identify star-forming galaxies at high redshifts. Our observations show no overdensity of star-forming galaxies in the fields of these quasars. The lack of (dust-free) luminous starburst companions indicates that the quasars may be the only massive galaxies in their vicinity undergoing a period of intense activity.Comment: 6 pages, 2 figures, contributed paper to Proceedings of the Conference "Growing Black Holes" held in Garching, Germany, June 21-25, 2004, edited by A. Merloni, S. Nayakshin and R. Sunyaev, Springer-Verlag series of "ESO Astrophysics Symposia

Quasars and the Big Blue Bump

We investigate the ultraviolet-to-optical spectral energy distributions (SEDs) of 17 active galactic nuclei (AGNs) using quasi-simultaneous spectrophotometry spanning 900-9000 Angstrom (rest frame). We employ data from the Far Ultraviolet Spectroscopic Explorer (FUSE), the Hubble Space Telescope (HST), and the 2.1-meter telescope at Kitt Peak National Observatory (KPNO). Taking advantage of the short-wavelength coverage, we are able to study the so-called "big blue bump," the region where the energy output peaks, in detail. Most objects exhibit a spectral break around 1100 Angstrom. Although this result is formally associated with large uncertainty for some objects, there is strong evidence in the data that the far-ultraviolet spectral region is below the extrapolation of the near-ultraviolet-optical slope, indicating a spectral break around 1100 Angstrom. We compare the behavior of our sample to those of non-LTE thin-disk models covering a range in black-hole mass, Eddington ratio, disk inclination, and other parameters. The distribution of ultraviolet-optical spectral indices redward of the break, and far-ultraviolet indices shortward of the break, are in rough agreement with the models. However, we do not see a correlation between the far-ultraviolet spectral index and the black hole mass, as seen in some accretion disk models. We argue that the observed spectral break is intrinsic to AGNs, although intrinsic reddening as well as Comptonization can strongly affect the far-ultraviolet spectral index. We make our data available online in digital format.Comment: 32 pages (10pt), 12 figures. Accepted for publication in Ap

HST STIS spectroscopy of the triple nucleus of M31: two nested disks in Keplerian rotation around a Supermassive Black Hole

We present HST spectroscopy of the nucleus of M31 obtained with STIS. Spectra taken around the CaT lines at 8500 see only the red giants in the double bright- ness peaks P1 and P2. In contrast, spectra taken at 3600-5100 A are sensitive to the tiny blue nucleus embedded in P2, the lower surface brightness red nucleus. P2 has a K-type spectrum, but the embedded blue nucleus has an A-type spectrum with strong Balmer absorption lines. Given the small likelihood for stellar collisions, a 200 Myr old starburst appears to be the most plausible origin of the blue nucleus. In stellar population, size, and velocity dispersion, the blue nucleus is so different from P1 and P2 that we call it P3. The line-of-sight velocity distributions of the red stars in P1+P2 strengthen the support for Tremaine s eccentric disk model. The kinematics of P3 is consistent with a circular stellar disk in Keplerian rotation around a super-massive black hole with M_bh = 1.4 x 10^8 M_sun. The P3 and the P1+P2 disks rotate in the same sense and are almost coplanar. The observed velocity dispersion of P3 is due to blurred rotation and has a maximum value of sigma = 1183+-201 km/s. The observed peak rotation velocity of P3 is V = 618+-81 km/s at radius 0.05" = 0.19 pc corresponding to a circular rotation velocity at this radius of ~1700 km/s. Any dark star cluster alternative to a black hole must have a half-mass radius <= 0.03" = 0.11 pc. We show that this excludes clusters of brown dwarfs or dead stars on astrophysical grounds.Comment: Astrophysical Journal, Sep 20, 2005, 21 pages including 20 figure

Occupational cancer in Britain: Exposure assessment methodology

To estimate the current occupational cancer burden due to past exposures in Britain, estimates of the number of exposed workers at different levels are required, as well as risk estimates of cancer due to the exposures. This paper describes the methods and results for estimating the historical exposures. All occupational carcinogens or exposure circumstances classified by the International Agency for Research on Cancer as definite or probable human carcinogens and potentially to be found in British workplaces over the past 20–40 years were included in this study. Estimates of the number of people exposed by industrial sector were based predominantly on two sources of data, the CARcinogen EXposure (CAREX) database and the UK Labour Force Survey. Where possible, multiple and overlapping exposures were taken into account. Dose–response risk estimates were generally not available in the epidemiological literature for the cancer–exposure pairs in this study, and none of the sources available for obtaining the numbers exposed provided data by different levels of exposure. Industrial sectors were therefore assigned using expert judgement to ‘higher'- and ‘lower'-exposure groups based on the similarity of exposure to the population in the key epidemiological studies from which risk estimates had been selected. Estimates of historical exposure prevalence were obtained for 41 carcinogens or occupational circumstances. These include exposures to chemicals and metals, combustion products, other mixtures or groups of chemicals, mineral and biological dusts, physical agents and work patterns, as well as occupations and industries that have been associated with increased risk of cancer, but for which the causative agents are unknown. There were more than half a million workers exposed to each of six carcinogens (radon, solar radiation, crystalline silica, mineral oils, non-arsenical insecticides and 2,3,7,8-tetrachlorodibenzo-p-dioxin); other agents to which a large number of workers are exposed included benzene, diesel engine exhaust and environmental tobacco smoke. The study has highlighted several industrial sectors with large proportions of workers potentially exposed to multiple carcinogens. The relevant available data have been used to generate estimates of the prevalence of past exposure to occupational carcinogens to enable the occupational cancer burden in Britain to be estimated. These data are considered adequate for the present purpose, but new data on the prevalence and intensity of current occupational exposure to carcinogens should be collected to ensure that future policy decisions be based on reliable evidence

Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey

The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed to locate quasars during the epoch of reionization. In this paper we present the discovery of the first four CFHQS quasars at redshift greater than 6, including the most distant known quasar, CFHQS J2329-0301 at z=6.43. We describe the observational method used to identify the quasars and present optical, infrared, and millimeter photometry and optical and near-infrared spectroscopy. We investigate the dust properties of these quasars finding an unusual dust extinction curve for one quasar and a high far-infrared luminosity due to dust emission for another. The mean millimeter continuum flux for CFHQS quasars is substantially lower than that for SDSS quasars at the same redshift, likely due to a correlation with quasar UV luminosity. For two quasars with sufficiently high signal-to-noise optical spectra, we use the spectra to investigate the ionization state of hydrogen at z>5. For CFHQS J1509-1749 at z=6.12, we find significant evolution (beyond a simple extrapolation of lower redshift data) in the Gunn-Peterson optical depth at z>5.4. The line-of-sight to this quasar has one of the highest known optical depths at z~5.8. An analysis of the sizes of the highly-ionized near-zones in the spectra of two quasars at z=6.12 and z=6.43 suggest the IGM surrounding these quasars was substantially ionized before these quasars turned on. Together, these observations point towards an extended reionization process, but we caution that cosmic variance is still a major limitation in z>6 quasar observations.Comment: 15 pages, 9 figures, AJ, in press, minor changes to previous versio

A Pair of Compact Red Galaxies at Redshift 2.38, Immersed in a 100 kpc Scale Ly-alpha Nebula

We present Hubble Space Telescope (HST) and ground-based observations of a pair of galaxies at redshift 2.38, which are collectively known as 2142-4420 B1 (Francis et al. 1996). The two galaxies are both luminous extremely red objects (EROs), separated by 0.8 arcsec. They are embedded within a 100 kpc scale diffuse Ly-alpha nebula (or blob) of luminosity ~10^44 erg/s. The radial profiles and colors of both red objects are most naturally explained if they are young elliptical galaxies: the most distant yet found. It is not, however, possible to rule out a model in which they are abnormally compact, extremely dusty starbursting disk galaxies. If they are elliptical galaxies, their stellar populations have inferred masses of ~10^11 solar masses and ages of ~7x10^8 years. Both galaxies have color gradients: their centers are significantly bluer than their outer regions. The surface brightness of both galaxies is roughly an order of magnitude greater than would be predicted by the Kormendy relation. A chain of diffuse star formation extending 1 arcsec from the galaxies may be evidence that they are interacting or merging. The Ly-alpha nebula surrounding the galaxies shows apparent velocity substructure of amplitude ~ 700 km/s. We propose that the Ly-alpha emission from this nebula may be produced by fast shocks, powered either by a galactic superwind or by the release of gravitational potential energy.Comment: 33 pages, 9 figures, ApJ in press (to appear in Jun 10 issue

Application of Dyes in Nonlinear Optical Materials

An outline of some azobenzene derivatives which are being used in ICI as the basis for new nonlinear optical materials is presented