468 research outputs found

    Les Habitudes de lecture des Québécois

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    Star formation rate and dynamical mass of 10^8 solar mass black hole host galaxies at redshift 6

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    We present ALMA observations of two moderate luminosity quasars at redshift 6. These quasars from the Canada-France High-z Quasar Survey (CFHQS) have black hole masses of ~10^8 M_solar. Both quasars are detected in the [CII] line and dust continuum. Combining these data with our previous study of two similar CFHQS quasars we investigate the population properties. We show that z>6 quasars have a significantly lower far-infrared luminosity than bolometric-luminosity-matched samples at lower redshift, inferring a lower star formation rate, possibly correlated with the lower black hole masses at z=6. The ratios of [CII] to far-infrared luminosities in the CFHQS quasars are comparable with those of starbursts of similar star formation rate in the local universe. We determine values of velocity dispersion and dynamical mass for the quasar host galaxies based on the [CII] data. We find that there is no significant offset from the relations defined by nearby galaxies with similar black hole masses. There is however a marked increase in the scatter at z=6, beyond the large observational uncertainties.Comment: 10 pages, 7 figures, accepted for publication in Ap

    L’Étoile Bleue : responsabiliser et revaloriser les jeunes psychiatrisés vivant dans la communauté

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    L'expérience du Café l'Étoile Bleue (Laval) vise à créer un lieu de passage alternatif où des jeunes psychiatrisé(e)s pourront développer les habiletés nécessaires pour briser Ie cadre d'interprétation négative qu'ils ont d'eux-mêmes, et réussir à se trouver une identité positive propre de même qu'une place dans la communauté. Pour ce faire, un milieu de travail à stress dosé, où les relations sont déprofessionnalisées et décloisonnées, parvient à susciter la participation des jeunes et leur désir de se prendre en charge.The experience of the Café l'Étoile Bleue (Laval) illustrates an attempt to create an alternative gateway where young psychiatric patients can develop the necessary skills to break through the negative view they have of themselves, thus achieving a positive identity as well as a position in the community. To do this, a working environment of controlled stress is provided where the interactions are not compartmentalised and limited to professionals. This succeeds in gaining the participation of the young people and prompts their desire to become responsible for their own lives

    A wide dispersion in star formation rate and dynamical mass of 10^8 solar mass black hole host galaxies at redshift 6

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    ALMA [CII] line and continuum observations of five redshift z>6 quasars are presented. This sample was selected to probe lower black hole mass quasars than most previous studies. We find a wide dispersion in properties with CFHQS J0216-0455, a low-luminosity quasar with absolute magnitude M_1450=-22.2, remaining undetected implying a limit on the star formation rate in the host galaxy of <10 solar masses per year, whereas other host galaxies have star formation rates up to hundreds of solar masses per year. Two other quasars have particularly interesting properties. VIMOS2911 is one of the least luminous z>6 quasars known with M_1450=-23.1, yet its host galaxy is experiencing a very powerful starburst. PSO J167-13 has a broad and luminous [CII] line and a neighbouring galaxy a projected distance of 5kpc away that is also detected in the [CII] line and continuum. Combining with similar observations from the literature, we study the ratio of [CII] line to far-infrared luminosity finding this ratio increases at high-redshift at a fixed far-infrared luminosity, likely due to lower dust content, lower metallicity and/or higher gas masses. We compile a sample of 21 high-redshift quasars with dynamical masses and investigate the relationship between black hole mass and dynamical mass. The new observations presented here reveal dynamical masses consistent with the relationship defined by local galaxies. However, the full sample shows a very wide scatter across the black hole mass - dynamical mass plane, whereas both the local relationship and simulations of high-redshift quasars show a much lower dispersion in dynamical mass.Comment: 10 pages, 11 figures, ApJ in pres

    Redshift 6.4 host galaxies of 10^8 solar mass black holes: low star formation rate and dynamical mass

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    We present ALMA observations of rest-frame far-infrared continuum and [CII] line emission in two z=6.4 quasars with black hole masses of ~10^8 M_sun. CFHQS J0210-0456 is detected in the continuum with a 1.2 mm flux of 120+/-35 microJy, whereas CFHQS J2329-0301 is undetected at a similar noise level. J2329-0301 has a star formation rate limit of <40 M_sun/yr, considerably below the typical value at all redshifts for this bolometric luminosity. By comparison with hydro simulations, we speculate that this quasar is observed at a relatively rare phase where quasar feedback has effectively shut down star formation in the host galaxy. [CII] emission is also detected only in J0210-0456. The ratio of [CII] to far-infrared luminosity is similar to that of low redshift galaxies of comparable luminosity, suggesting the previous finding of an offset in the relationships between this ratio and far-infrared luminosity at low- and high-redshift may be partially due to a selection effect from the limited sensitivity of previous observations. The [CII] line of J0210-0456 is relatively narrow (FWHM=189+/-18 km/s), indicating a dynamical mass substantially lower than expected from the local black hole - velocity dispersion correlation. The [CII] line is marginally resolved at 0.7" resolution with the blue and red wings spatially offset by 0.5" (3 kpc) and a smooth velocity gradient of 100 km/s across a scale of 6 kpc, possibly due to rotation of a galaxy-wide disk. These observations are consistent with the idea that stellar mass growth lags black hole accretion for quasars at this epoch with respect to more recent times.Comment: 8 pages, 7 figures, ApJ in press, replaced with final versio

    Les agressions en milieu psychiatrique. Vécu et perceptions des intervenants du Pavillon Roland-Saucier du Complexe hospitalier de la Sagamie

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    Cet article présente les résultats d'une étude effectuée au Pavillon Roland-Saucier, aile psychiatrique du Complexe hospitalier de la Sagamie. Le but poursuivi était d'explorer, par une approche phénoménologique, la problématique des agressions dont les intervenants étaient victimes de la part de bénéficiaires, et particulièrement l'impact de ces agressions sur leur vie professionnelle. Trente intervenants de différentes catégories professionnelles, sélectionnés par une procédure aléatoire stratifiée, ont accepté d'accorder des entrevues. L'analyse de ces entrevues a permis de dégager des éléments importants sur la base desquels diverses recommandations ont été formulées en vue d'améliorer la situation.This article presents results of a study conducted at the Pavillon Roland-Saucier, the psychiatric ward of the Complexe hospitalier de la Sagamie. The objective was to explore with a phenomenological approach the issue of assaults by patients of mental health workers and in particular the impact of theses assaults on their professional life. Thirty workers of various professional categories, selected by a stratified random procedure, have accepted to be interviewed. The analysis of theses interviews has allowed to draw important elements on the basis which various recommendations have been suggested in order to improve the situation.Este articulo presenta los resultados de un estudio efectuado en el ala psiquiátrica del Pabellón Roland-Saucier del complejo hospitalario de la Sagamie. El objetivo era el de explorar por medio de un enfoque fenomenologico, el problema de las agresiones de las que los trabajadores eran víctimas de parte de los beneficiarios, y particularmente del impacto de esas agresiones en sus vidas profesionales. Treinta trabajadores de diferentes categorías profesionales, seleccionados por un procedimiento aleatorio estratificado, aceptaron acordar entrevistas. El análisis de estas entrevistas permitió despejar los elementos importantes y diversas recomendaciones fueron emitidas sobre esta base, con el fin de mejorar la situación

    Mid-Infrared Selected Quasars I: Virial Black Hole Mass and Eddington Ratios

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    We provide a catalog of 391 mid-infrared-selected (MIR, 24μ\mum) broad-emission-line (BEL, type 1) quasars in the 22 deg2^2 SWIRE Lockman Hole field. This quasar sample is selected in the MIR from Spitzer MIPS with S24>400μS_{\rm 24} > 400\muJy, jointly with an optical magnitude limit of r (AB) << 22.5 for broad line identification. The catalog is based on MMT and SDSS spectroscopy to select BEL quasars, extends the SDSS coverage to fainter magnitudes and lower redshifts, and recovers a more complete quasar population. The MIR-selected quasar sample peaks at zz\sim1.4, and recovers a significant and constant (20\%) fraction of extended objects with SDSS photometry across magnitudes, which was not included in the SDSS quasar survey dominated by point sources. This sample also recovers a significant population of z19.1z 19.1. We then investigate the continuum luminosity and line profiles of these MIR quasars, and estimate their virial black hole masses and the Eddington ratios. The SMBH mass shows evidence of downsizing, though the Eddington ratios remain constant at 1<z<41 < z < 4. Compared to point sources in the same redshift range, extended sources at z<1z < 1 show systematically lower Eddington ratios. The catalog and spectra are publicly available online.Comment: 72 pages, 27 figures, 16 tables; ApJ accepte

    The z=0.0912 and z=0.2212 Damped Lyman Alpha Galaxies Along the Sight-Line Toward the Quasar OI 363

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    New optical and infrared observations along the sight-line toward the quasar OI 363 (0738+313) are presented and discussed. Excluding systems which lack confirming UV spectroscopic observations of the actual Lyman alpha line, this sight-line presently contains the two lowest-redshift classical damped Lyman alpha (DLA) quasar absorption line systems known (i.e. with N(HI) \ge 2 x 10^{20} atoms cm^{-2}), one at z(abs)=0.0912 and the other at z(abs)=0.2212. The z=0.09 DLA galaxy appears to be an extended low surface brightness galaxy which is easily visible only in infrared images and shows rich morphological structure. Subtraction of the quasar nuclear and host light yields L_K \approx 0.08L_K* at z=0.09. The impact parameter between the galaxy and quasar sight-line is very small, b<3.6 kpc (<2 arcsec), which makes measurements difficult. The z=0.22 DLA galaxy is an early-type dwarf with a K-band luminosity of L_K \approx 0.1L_K* at impact parameter b=20 kpc. In general, these results serve to support mounting evidence that DLA galaxies are drawn from a wide variety of gas-rich galaxy types. (Abridged)Comment: 27 pages, 6 figures, 2 in color. Submitted to Ap

    A Population of Dust-rich Quasars at z ~ 1.5

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    We report Herschel SPIRE (250, 350, and 500 μm) detections of 32 quasars with redshifts 0.5 ≤z < 3.6 from the Herschel Multi-tiered Extragalactic Survey (HerMES). These sources are from a MIPS 24 μm flux-limited sample of 326 quasars in the Lockman Hole Field. The extensive multi-wavelength data available in the field permit construction of the rest-frame spectral energy distributions (SEDs) from ultraviolet to the mid-infrared for all sources, and to the far-infrared (FIR) for the 32 objects. Most quasars with Herschel FIR detections show dust temperatures in the range of 25-60 K, with a mean of 34 K. The FIR luminosities range from 10^(11.3) to 10^(13.5) L_☉, qualifying most of their hosts as ultra- or hyper-luminous infrared galaxies. These FIR-detected quasars may represent a dust-rich population, but with lower redshifts and fainter luminosities than quasars observed at ~1 mm. However, their FIR properties cannot be predicted from shorter wavelengths (0.3-20 μm, rest frame), and the bolometric luminosities derived using the 5100 Å index may be underestimated for these FIR-detected quasars. Regardless of redshift, we observed a decline in the relative strength of FIR luminosities for quasars with higher near-infrared luminosities

    Infrared and Optical Observations of GRB 030115 and its Extremely Red Host Galaxy: Implications for Dark Bursts

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    We present near-infrared (nIR) and optical observations of the afterglow of GRB 030115. Discovered in an infrared search at Kitt Peak 5 hours after the burst trigger, this afterglow is amongst the faintest observed in the R-band at an early epoch, and exhibits very red colors, with RK6R-K\approx 6. The magnitude of the optical afterglow of GRB 030115 is fainter than many upper limits for other bursts, suggesting that without early nIR observations it would have been classified as a ``dark'' burst. Both the color and optical magnitude of the afterglow are likely due to dust extinction and indicate that at least some optical afterglows are very faint due to dust along the line of sight. Multicolor {\it Hubble Space Telescope} observations were also taken of the host galaxy and the surrounding field. Photometric redshifts imply that the host, and a substantial number of faint galaxies in the field are at z2.5z \sim 2.5. The overdensity of galaxies is sufficiently great that GRB 030115 may have occurred in a rich high-redshift cluster. The host galaxy shows extremely red colors (R-K=5) and is the first GRB host to be classified as an Extremely Red Object (ERO). Some of the galaxies surrounding the host also show very red colors, while the majority of the cluster are much bluer, indicating ongoing unobscured star formation. As it is thought that much of high redshift star formation occurs in highly obscured environments it may be that GRB 030115 represent a transition object, between the relatively unobscured afterglows seen to date and a population which are very heavily extinguished, even in the nIR.Comment: 19 Pages. ApJ 2006, 647, 47
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