3,284 research outputs found

    Large-Scale Structures Behind the Southern Milky Way from Observations of Partially Obscured Galaxies

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    We report here on extragalactic large-scale structures uncovered by a deep optical survey for galaxies behind the southern Milky Way. Systematic visual inspection of the ESO/SRC-survey revealed over 10000 previously unknown galaxies in the region 265 < l < 340, |b| < 10. With subsequently obtained redshifts of more than 10% of these galaxies, new structures across the Milky Way are unveiled, such as a filament at ~ 2500 km/s connecting to the Hydra and Antlia clusters, a shallow extended supercluster in Vela (~ 6000km/s), and a nearby (4882 km/s), very massive (M ~ 2-5 10^15 Msun), rich Coma-like cluster which seems to constitute the previously unidentified center of the Great Attractor. The innermost part of the Milky Way where the foreground obscuration in the blue is 5mag, respectively HI-column densities greater than 6 10^21 / cm^2 remains fully opaque. In this approximately 8 degrees wide strip, the forthcoming blind HI-survey with the multi-beam system at Parkes will provide the only tool to unveil this part of the extragalactic sky.Comment: Presented at the Multibeam Workshop on ``HI in the Local Universe'', Sydney, May 13-15 1996. Accepted 2.11.1996 for publication by PASA. Latex-file with 4 encapsulated postscript files. Version with original figures available at http://www.atnf.csiro.au/~lstavele/13beam/proceedings/korteweg/korteweg.htm

    DENIS Observations of Multibeam Galaxies in the Zone of Avoidance

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    Roughly 25% of the optical extragalactic sky is obscured by the dust and stars of our Milky Way. Dynamically important structures might still lie hidden in this zone. Various surveys are presently being employed to uncover the galaxy distribution in the Zone of Avoidance (ZOA) but all suffer from (different) limitations and selection effects. We illustrate the promise of using a multi-wavelength approach for extragalactic large-scale studies behind the ZOA, i.e. a combination of three surveys -- optical, systematic blind HI and near-infrared (NIR), which will allow the mapping of the peculiar velocity field in the ZOA through the NIR Tully-Fisher relation. In particular, we present here the results of cross-identifying HI-detected galaxies with the DENIS NIR survey, and the use of NIR colours to determine foreground extinctions.Comment: Accepted for publication in PASA. Proceedings of workshop "HI in the Local Universe, II", held in Melbourne, Sept. 1998. 9 pages, LaTeX2e, 2 encapsulated PS figures, 3 JPEG figures, Full resolution figures 2, 3 and 4 and full resolution paper are at ftp://ftp.iap.fr/pub/from_users/gam/PAPERS/HICONF

    Quarkonium Production Studies in CMS

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    When the LHC starts its operation, CMS will have a unique opportunity to study q uarkonium production in pp collisions and later in PbPb collisions. Here we report on the methods and plans for measuring the differential pT Jpsi->mu+mu- production cross section, using data to be collected in the first LHC run by the CMS detector. Furthermore we discuss the performance of the CMS detector for quarkonium measurements in PbPb collisions.Comment: Presented at the 34th International Conference on High Energy Physic

    An Overview of Uncovered and Suspected Large-Scale Structures behind the Milky Way

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    Various dynamically important extragalactic large-scale structures in the local Universe lie behind the Milky Way. Most of these structures (predicted and unexpected) have only recently been made ``visible'' through dedicated deep surveys at various wavelengths. The wide range of observational searches (optical, near infrared, far infrared, radio and X-ray) for galaxies in the Zone of Avoidance (ZOA) will be reviewed and the uncovered and suspected large-scale structures summarised. Particular emphasis is given to the Great Attractor region where the existence of yet another cluster is suspected (Woudt 1998). Predictions from reconstructions of the density field in the ZOA are discussed and compared with observational evidence. Although no major structures are predicted out to about v < 10000 km/s for which no observational evidence exists, the comparison between reconstructed density fields and the observed galaxy distribution remain important as they allow derivations of the density and biasing parameters.Comment: To appear in PASA 16. Proceedings of workshop "HI in the Local Universe, II", held in Melbourne, Sept. 1998. 9 pages, LaTeX2e, 1 encapsulated PS figur

    Extragalactic Large-Scale Structures behind the Southern Milky Way. IV. Redshifts Obtained with MEFOS

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    Abbreviated: As part of our efforts to unveil extragalactic large-scale structures behind the southern Milky Way, we here present redshifts for 764 galaxies in the Hydra/Antlia, Crux and Great Attractor region (266deg < l < 338deg, |b| < 10deg), obtained with the Meudon-ESO Fibre Object Spectrograph (MEFOS) at the 3.6-m telescope of ESO. The observations are part of a redshift survey of partially obscured galaxies recorded in the course of a deep optical galaxy search behind the southern Milky Way. A total of 947 galaxies have been observed, a small percentage of the spectra (N=109, 11.5%) were contaminated by foreground stars, and 74 galaxies (7.8%) were too faint to allow a reliable redshift determination. With MEFOS we obtained spectra down to the faintest galaxies of our optical galaxy survey, and hence probe large-scale structures out to larger distances (v <~ 30000 km/s) than our other redshift follow-ups. The most distinct large-scale structures revealed in the southern Zone of Avoidance are discussed in context to known structures adjacent to the Milky Way.Comment: 11 pages, 7 figures; accepted for publication in A&A. Tables 1 and 2 will be available in electronic format at the CDS. Figure 1 at full resolution, and both tables are available at http://mensa.ast.uct.ac.za/~pwoudt/data/H4462/

    Large-Scale Structures Behind the Milky Way from Near-IR Surveys

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    About 25% of the optical extragalactic sky is obscured by the dust and stars of our Milky Way. Dynamically important structures might still lie hidden in this zone. Various approaches are presently being employed to uncover the galaxy distribution in the Zone of Avoidance (ZOA) but all suffer from (different) limitations and selection effects. We investigated the potential of using the DENIS NIR survey for studies of galaxies behind the obscuration layer of our Milky Way and for mapping the Galactic extinction. As a pilot study, we recovered DENIS I, J and K band images of heavily obscured but optically still visible galaxies. We determined the I, J and K band luminosity functions of galaxies on three DENIS strips that cross the center of the nearby, low-latitude, rich cluster Abell 3627. The extinction-corrected I-J and J-K colours of these cluster galaxies compare well with that of an unobscured cluster. We searched for and identified galaxies at latitudes where the Milky Way remains fully opaque (|b| 4-5mag) - in a systematic search as well as around positions of galaxies detected with the blind HI survey of the ZOA currently conducted with the Multibeam Receiver of the Parkes Radiotelescope.Comment: 12 pages, including 5 PS figures, LaTeX, uses crckapb.sty and epsf.tex. Better resolved figures available upon request. To appear in proceedings of the 3rd Euroconference (Meudon, France, June 1997) on ``The Impact of Near IR Surveys'', Kluwer 199
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