203 research outputs found

    The X-ray properties of the merging galaxy pair NGC 4038/9 - the Antennae

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    We report the results of an X-ray spectral imaging observation of the Antennae with the ROSAT PSPC. 55% of the soft X-ray flux from the system is resolved into discrete sources, including components identified with the galactic nuclei and large HII regions, whilst the remainder appears to be predominantly genuinely diffuse emission from gas at a temperature ~4x10^6 K. The morphology of the emission is unusual, combining a halo which envelopes the galactic discs, with what appears to be a distorted, but well-collimated bipolar outflow. We derive physical parameters for the hot gas in both diffuse components, which are of some interest, given that the Antennae probably represents an elliptical galaxy in the making.Comment: 15 pages plus 9 figures, uuencoded encapsulated postscript file. Accepted for publication in MNRA

    The properties of highly luminous IRAS galaxies

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    From a complete sample of 154 galaxies identified with IRAS sources in a 304 sq deg area centered on the South Galactic Pole, a subsample of 58 galaxies with L sub IR/L sub B > 3 was chosen. Low resolution spectra were obtained for 30% of the subsample and redshifts and relative emission line intensities were derived. As a class these galaxies are very luminous with = 2.9 x 10 to the 11th power L sub 0 and (L sub IR) max = 1.3 x 10 to the 12th power L sub 0. CCD images and JHK photometry were obtained for many of the subsample. The galaxies are for the most part newly identified and are optically faint, with a majority showing evidence of a recent interaction. Radio continuum observations of all galaxies of the subsample were recently obtained at 20 cm VLA with about 75% being detected in a typical integration time of about 10 minutes

    Three quasars from a survey of strong 25-”m emitters

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    We have carried out a spectroscopic survey of 750 sources that are strong 25-ÎŒm emitters from the IRAS Faint Source data base. Many of these sources are previously unknown active galactic nuclei including new IRAS quasars, three of which we describe here: F21382−2659, Z06367−6845 and Z05558−5008. They are all radio and X-ray quiet, and compared to the known IRAS quasars they have similar 25-ÎŒm luminosities, L(25 ÎŒm), but lower values of L(25 ÎŒm)/L(B). Their F(25 ÎŒm)/F(60 ÎŒm) IRAS colours lie in the range 0.33 to 1.08, indicating the presence of relatively warm dust, presumably in a dusty torus surrounding the central source, and with temperatures similar to those of the known IRAS quasars. The quasar with the warmest dust, F21382−2659, exhibits broad (full width at half-maximum ~4000 km s^(−1)) asymmetric Balmer lines with HÎł having an opposite asymmetry to the other broad lines; also HÎČ (only) is double-peaked. Fe ii is very weak in F21382−2659 but strong in the other two quasars, and the anticorrelation between Fe ii and [O iii] holds as anticipated. Two of the quasars are unpolarized: although F21382−2659 is optically polarized (2.1 per cent at 4950 Å), we argue that this provides little insight into the orientation of its dust torus relative to the line of sight

    BioCatalogue: a universal catalogue of web services for the life sciences

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    The use of Web Services to enable programmatic access to on-line bioinformatics is becoming increasingly important in the Life Sciences. However, their number, distribution and the variable quality of their documentation can make their discovery and subsequent use difficult. A Web Services registry with information on available services will help to bring together service providers and their users. The BioCatalogue (http://www.biocatalogue.org/) provides a common interface for registering, browsing and annotating Web Services to the Life Science community. Services in the BioCatalogue can be described and searched in multiple ways based upon their technical types, bioinformatics categories, user tags, service providers or data inputs and outputs. They are also subject to constant monitoring, allowing the identification of service problems and changes and the filtering-out of unavailable or unreliable resources. The system is accessible via a human-readable ‘Web 2.0’-style interface and a programmatic Web Service interface. The BioCatalogue follows a community approach in which all services can be registered, browsed and incrementally documented with annotations by any member of the scientific community

    Systematic identification of IRAS point sources

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    A large scale program was initiated to identify IRAS point sources. At ROE the ideal facilities are at hand to undertake such a large program, viz. the rapid scanning capabilities of the COSMOS measuring machine to exploit the depth and resolution of the U.K. Schmidt Telescope J survey plates. Sources in 44 Schmidt plate areas were identified including 1300 sources and covering 1100 square degrees. The identification comprise 700 galaxy identifications and 600 stellar identifications. There are also about 40 sources with no obvious identification but which can be most easily explained by cirrus, confusion between two sources or sources just outside the 2 sigma error box. A major aim with the galaxy identification is to provide a data base from which sound statistical analyses can be made. Accurate blue magnitudes and morphological classifications for each identification were produced

    The Importance of Grey and Qualitative Literature in Developing Domestic Violence and Abuse and Child Maltreatment Core Outcome Sets: A Brief Report

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    Purpose: Core Outcome Sets (COS) are agreed sets of outcomes to be used in all trials that evaluate the effect of interventions. This report considers the added value of including grey and qualitative literature in a study to identify COSs of family-focused interventions for CM and DVA. / Methods: We identified outcomes of interventions for DVA or CM through systematically searching 12 academic databases and 86 organisation websites, leading to the inclusion of 485 full-text reports across 6 reviews. We developed a candidate outcome longlist comprising 347 extracted outcomes. / Results: We identified 87% (282/347) of candidate outcomes from the grey and qualitative literature, and 37% (127/347) from the trial literature. Of the candidate outcomes on the longlist, 22% (75/347) were identified solely from the grey or qualitative literature and 7% (26/347) from trial literature. Three of the eight outcomes in the final core outcome sets may have been missed if grey or qualitative literature had not been searched. / Conclusions: The qualitative and grey literature adds DVA and CM outcomes that are relevant to survivor perspectives but not reported in trials; this had an impact on the final COSs. It is important for COS developers to consider what they may be missing if they do not search the qualitative and grey literature

    The Phoenix Deep Survey: Optical and near infrared imaging catalogs

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    The Phoenix Deep Survey is a multi-wavelength galaxy survey based on deep 1.4 GHz radio imaging (Hopkins et al., 2003). The primary goal of this survey is to investigate the properties of star formation in galaxies and to trace the evolution in those properties to a redshift z=1, covering a significant fraction of the age of the Universe. By compiling a sample of star-forming galaxies based on selection at radio wavelengths we eliminate possible biases due to dust obscuration, a significant issue when selecting objects at optical and ultraviolet wavelengths. In this paper, we present the catalogs and results of deep optical (UBVRI) and near-infrared (Ks) imaging of the deepest region of the existing decimetric radio imaging. The observations and data-processing are summarised and the construction of the optical source catalogs described, together with the details of the identification of candidate optical counterparts to the radio catalogs. Based on our UBVRIKs imaging, photometric redshift estimates for the optical counterparts to the radio detections are explored.Comment: 56 pages inc. 16 page table; November issue of ApJ

    The Far-Infrared Spectral Energy Distributions of X-ray-selected Active Galaxies

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    [Abridged] We present ISO far-infrared (IR) observations of 21 hard X-ray selected AGN from the HEAO-1 A2 sample. We compare the far-IR to X-ray spectral energy distributions (SEDs) of this sample with various radio and optically selected AGN samples. The hard-X-ray selected sample shows a wider range of optical/UV shapes extending to redder near-IR colors. The bluer objects are Seyfert 1s, while the redder AGN are mostly intermediate or type 2 Seyferts. This is consistent with a modified unification model in which the amount of obscuring material increases with viewing angle and may be clumpy. Such a scenario, already suggested by differing optical/near-IR spectroscopic and X-ray AGN classifications, allows for different amounts of obscuration of the continuum emission in different wavebands and of the broad emission line region which results in a mixture of behaviors for AGN with similar optical emission line classifications. The resulting limits on the column density of obscuring material through which we are viewing the redder AGN are 100 times lower than for the standard optically thick torus models. The resulting decrease in optical depth of the obscuring material allows the AGN to heat more dust at larger radial distances. We show that an AGN-heated, flared, dusty disk with mass 10^9 solar and size of few hundred pc is able to generate optical-far-IR SEDs which reproduce the wide range of SEDs present in our sample with no need for an additional starburst component to generate the long-wavelength, cooler part of the IR continuum.Comment: 40 pages, 14 figures, accepted for publication in Astrophysical Journal, V. 590, June 10, 200
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