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5 results on '"A. O. H. Olofsson"'

1. Characterization of a dense aperture array for radio astronomy

Author

C. Taffoureau, B. Censier, Aris Karastergiou, P. Picard, P. Renaud, A. O. H. Olofsson, Steve Torchinsky, M. Serylak, Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Onsala Space Observatory (OSO), Chalmers University of Technology [Göteborg], Oxford Astrophysics, University of Oxford [Oxford], SKA South Africa, Department of Physics and Astronomy [South Africa], and University of the Western Cape

Subjects
Aperture array, Aperture, Computer science, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Optics, Techniques: radio astronomy, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Calibration, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Large field of view, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, 020206 networking & telecommunications, Astronomy and Astrophysics, Characterization (materials science), [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Square Kilometre Array, Square kilometre array, Space and Planetary Science, Instrumentation: interferometers, Antenna (radio), business, Astrophysics - Instrumentation and Methods for Astrophysics, Radio astronomy
Abstract

EMBRACE@Nancay is a prototype instrument consisting of an array of 4608 densely packed antenna elements creating a fully sampled, unblocked aperture. This technology is proposed for the Square Kilometre Array and has the potential of providing an extremely large field of view making it the ideal survey instrument. We describe the system,calibration procedures, and results from the prototype., 17 pages, accepted for publication in A&A

Published
2016
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2. EMBRACE@Nancay: an ultra wide field of view prototype for the SKA

Author

P. Renaud, C. Taffoureau, B. Censier, A. O. H. Olofsson, Steve Torchinsky, Aris Karastergiou, M. Serylak, Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Onsala Space Observatory (OSO), Chalmers University of Technology [Göteborg], Oxford Astrophysics, University of Oxford [Oxford], Department of Physics and Astronomy [South Africa], University of the Western Cape, Department of Physics-Electronics, Rhodes University, Grahamstown, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)

Subjects
[PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Instrument optimisation, Computer science, media_common.quotation_subject, FOS: Physical sciences, Field of view, 02 engineering and technology, Astrophysics::Cosmology and Extragalactic Astrophysics, radio astronomy, 01 natural sciences, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Angular resolution, Instrumental noise, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Instrumentation, Mathematical Physics, media_common, Radio equipment, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, 020206 networking & telecommunications, interferometry, Galaxy, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Interferometry, Square Kilometre Array, Sky, Antennas, Baryon acoustic oscillations, Astrophysics - Instrumentation and Methods for Astrophysics, Radio astronomy
Abstract

A revolution in radio receiving technology is underway with the development of densely packed phased arrays for radio astronomy. This technology can provide an exceptionally large field of view, while at the same time sampling the sky with high angular resolution. Such an instrument, with a field of view of over 100 square degrees, is ideal for performing fast, all-sky, surveys, such as the "intensity mapping" experiment to measure the signature of Baryonic Acoustic Oscillations in the HI mass distribution at cosmological redshifts. The SKA, built with this technology, will be able to do a billion galaxy survey. I will present a very brief introduction to radio interferometry, as well as an overview of the Square Kilometre Array project. This will be followed by a description of the EMBRACE prototype and a discussion of results and future plans., Comment: to appear in proceedings of the INFIERI Summer School INtelligent Signal Processing for FrontIEr Research and Industry, Paris 2014

Published
2014
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3. Ground-state ammonia and water in absorption towards Sgr B2

Author

John H. Black, Pierre Encrenaz, Michael Olberg, A. O. H. Olofsson, Eva Wirström, Åke Hjalmarson, Urban Frisk, Aa. Sandqvist, Edith Falgarone, B. Larsson, Per Bergman, Onsala Space Observatory, Chalmers University of Technology (OSO), Stockholm Observatory, AlbaNova University Center, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Instrumentation et télédétection, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Dynamique des milieux interstellaires et plasmas stellaires, and Swedish Space Corporation (SSC)

Subjects
Physics, Molecular cloud, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Space and Planetary Science, Nucleosynthesis, Astrophysics of Galaxies (astro-ph.GA), Isotopologue, Disc, Absorption (electromagnetic radiation), Ground state, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Line (formation)
Abstract

We have used the Odin submillimetre-wave satellite telescope to observe the ground state transitions of ortho-ammonia and ortho-water, including their 15N, 18O, and 17O isotopologues, towards Sgr B2. The extensive simultaneous velocity coverage of the observations, >500 km/s, ensures that we can probe the conditions of both the warm, dense gas of the molecular cloud Sgr B2 near the Galactic centre, and the more diffuse gas in the Galactic disk clouds along the line-of-sight. We present ground-state NH3 absorption in seven distinct velocity features along the line-of-sight towards Sgr B2. We find a nearly linear correlation between the column densities of NH3 and CS, and a square-root relation to N2H+. The ammonia abundance in these diffuse Galactic disk clouds is estimated to be about (0.5-1)e-8, similar to that observed for diffuse clouds in the outer Galaxy. On the basis of the detection of H218O absorption in the 3 kpc arm, and the absence of such a feature in the H217O spectrum, we conclude that the water abundance is around 1e-7, compared to ~1e-8 for NH3. The Sgr B2 molecular cloud itself is seen in absorption in NH3, 15NH3, H2O, H218O, and H217O, with emission superimposed on the absorption in the main isotopologues. The non-LTE excitation of NH3 in the environment of Sgr B2 can be explained without invoking an unusually hot (500 K) molecular layer. A hot layer is similarly not required to explain the line profiles of the 1_{1,0}-1_{0,1} transition from H2O and its isotopologues. The relatively weak 15NH3 absorption in the Sgr B2 molecular cloud indicates a high [14N/15N] isotopic ratio >600. The abundance ratio of H218O and H217O is found to be relatively low, 2.5--3. These results together indicate that the dominant nucleosynthesis process in the Galactic centre is CNO hydrogen burning., 10 pages, 5 figures

Published
2010
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4. Molecular oxygen in the rho Ophiuchi cloud

Author

Nicholas F. H Tothill, Alain Klotz, René Liseau, P. A. Feldman, Christine D. Wilson, Maryvonne Gerin, N. Biver, Steve Torchinsky, G. F. Gahm, Cathy Horellou, H. G. Floren, George F. Mitchell, Alain Lecacheux, Laurent Pagani, Urban Frisk, G. Olofsson, John H. Black, Georg Witt, V. Buat, E. Kyroelae, Gérard Mégie, G. Serra, Hans Rickman, Roy Booth, Tatsuhiko I. Hasegawa, L. Nordh, Aa. Hjalmarson, Peter F. Bernath, Anders Winnberg, Per Bergman, L.-Aa. Nyman, L. E. B. Johansson, Gustaf Rydbeck, A. O. H. Olofsson, P. J. Encrenaz, Kevin Volk, G. Persson, E. Falgarone, M. Fich, Michael Olberg, I. Ristorcelli, S. Lundin, Aa. Sandqvist, Fredrik von Schéele, Magnus Dahlgren, Rene Plume, Donal P. Murtagh, M. Hagstroem, Charles L. Curry, Bengt Larsson, Hans Olofsson, Sun Kwok, Jacques Crovisier, Tommy Wiklind, Kay Justtanont, E. J. Llewellyn, Jorma Harju, Mathias Fredrixon, T. Liljestroem, Stockholm Observatory, AlbaNova University Center, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Onsala Space Observatory, Chalmers University of Technology (OSO), Department of Physics, University of Waterloo, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique des plasmas, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d'Astronomie Spatiale (LAS), Centre National de la Recherche Scientifique (CNRS), National Research Council of Canada (NRC), Swedish Space Corporation (SSC), Jakokoski Observatory, University of Helsinki, University of Calgary, Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Finnish Meteorological Institute (FMI), Metsähovi Radio Observatory, University of Saskatchewan [Saskatoon] (U of S), Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Department of Astronomy and Physics, Saint Mary's University, Global Environmental Measurements Group, Swedish National Space Board (SNSB), APEX team, ESO, Santiago, Uppsala Astronomical Observatory, Canadian Space Agency (CSA), Department of Physics and Astronomy, McMaster University, and Department of Meteorology, Stockholm University

Subjects
Physics, Molecular cloud, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Spectral line, Interstellar medium, Chemical species, Space and Planetary Science, Satellite, Ground state, Spectroscopy, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Line (formation)
Abstract

Molecular oxygen, O2 has been expected historically to be an abundant component of the chemical species in molecular clouds and, as such, an important coolant of the dense interstellar medium. However, a number of attempts from both ground and from space have failed to detect O2 emission. The work described here uses heterodyne spectroscopy from space to search for molecular oxygen in the interstellar medium. The Odin satellite carries a 1.1 m sub-millimeter dish and a dedicated 119 GHz receiver for the ground state line of O2. Starting in 2002, the star forming molecular cloud core rho Oph A was observed with Odin for 34 days during several observing runs. We detect a spectral line at v(LSR) = 3.5 km/s with dv(FWHM) = 1.5 km/s, parameters which are also common to other species associated with rho Ohp A. This feature is identified as the O2 (N_J = 1_1 - 1_0) transition at 118 750.343 MHz. The abundance of molecular oxygen, relative to H2,, is 5E-8 averaged over the Odin beam. This abundance is consistently lower than previously reported upper limits., Comment: 10 pages, 11 figures, accepted for publication in A&A

Published
2007
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5. Submillimeter emission from water in the W3 region

Author

Urban Frisk, A. M. Mason, Jorma Harju, Christine D. Wilson, M. Fich, A. O. H. Olofsson, Åke Hjalmarson, L. Nordh, Per Bergman, René Liseau, Kevin Volk, Aa. Sandqvist, H. G. Floren, Pierre Encrenaz, V. Buat, Rene Plume, Charles L. Curry, Laurent Pagani, E. Falgarone, L. Ristorcelli, Bengt Larsson, Tetsuo Hasegawa, K. Mattila, F. von Schéele, N. Boudet, Sun Kwok, G. Olofsson, G. Serra, Nicholas F. H Tothill, Mika Juvela, P. A. Feldman, Maryvonne Gerin, E. M. Gregersen, Alain Lecacheux, George F. Mitchell, Michael Olberg, Roy Booth, T. Liljeström, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique des plasmas, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), and Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Relative strength, Astrophysics, Absorption (electromagnetic radiation), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Spectral line, Line (formation)
Abstract

We have mapped the submillimeter emission from the 1(10)-1(01) transition of ortho-water in the W3 star-forming region. A 5'x5' map of the W3 IRS4 and W3 IRS5 region reveals strong water lines at half the positions in the map. The relative strength of the Odin lines compared to previous observations by SWAS suggests that we are seeing water emission from an extended region. Across much of the map the lines are double-peaked, with an absorption feature at -39 km/s; however, some positions in the map show a single strong line at -43 km/s. We interpret the double-peaked lines as arising from optically thick, self-absorbed water emission near the W3 IRS5, while the narrower blue-shifted lines originate in emission near W3 IRS4. In this model, the unusual appearance of the spectral lines across the map results from a coincidental agreement in velocity between the emission near W3 IRS4 and the blue peak of the more complex lines near W3 IRS5. The strength of the water lines near W3 IRS4 suggests we may be seeing water emission enhanced in a photon-dominated region., Accepted to A&A Letters as part of the special Odin issue; 4 pages

Published
2003
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