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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
Studying Galactic interstellar turbulence through fluctuations in synchrotron emission: First LOFAR Galactic foreground detection
Astronomy and Astrophysics, Volume 558, Article A72, Year 2013
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Description
Aims. The characteristic outer scale of turbulence (i.e. the scale at which the dominant source of turbulence injects energy to the interstellar medium) and the ratio of the random to ordered components of the magnetic field are key parameters to characterise magnetic turbulence in the interstellar gas, which affects the propagation of cosmic rays within the Galaxy. We provide new constraints to those two parameters. Methods. We use the LOw Frequency ARray (LOFAR) to image the diffuse continuum emission in the Fan region at (l,b) ∼ (137.0, +7.0) at 80′′ × 70′′ resolution in the range [146, 174] MHz. We detect multi-scale fluctuations in the Galactic synchrotron emission and compute their power spectrum. Applying theoretical estimates and derivations from the literature for the first time, we derive the outer scale of turbulence and the ratio of random to ordered magnetic field from the characteristics of these fluctuations. Results. We obtain the deepest image of the Fan region to date and find diffuse continuum emission within the primary beam. The power spectrum displays a power law behaviour for scales between 100 and 8 arcmin with a slope α =-1.84 ± 0.19. We find an upper limit of ∼20 pc for the outer scale of the magnetic interstellar turbulence toward the Fan region, which is in agreement with previous estimates in literature. We also find a variation of the ratio of random to ordered field as a function of Galactic coordinates, supporting different turbulent regimes. Conclusions. We present the first LOFAR detection and imaging of the Galactic diffuse synchrotron emission around 160 MHz from the highly polarized Fan region. The power spectrum of the foreground synchrotron fluctuations is approximately a power law with a slope α ≈-1.84 up to angular multipoles of ≤1300, corresponding to an angular scale of ∼8 arcmin. We use power spectra fluctuations from LOFAR as well as earlier GMRT and WSRT observations to constrain the outer scale of turbulence (Lout) of the Galactic synchrotron foreground, finding a range of plausible values of 10-20 pc. Then, we use this information to deduce lower limits of the ratio of ordered to random magnetic field strength. These are found to be 0.3, 0.3, and 0.5 for the LOFAR, WSRT and GMRT fields considered respectively. Both these constraints are in agreement with previous estimates. © 2013 ESO.
Authors & Co-Authors
Iacobelli, Marco
Netherlands, Leiden
Sterrewacht Leiden
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Haverkorn, Marijke
Netherlands, Leiden
Sterrewacht Leiden
Netherlands, Nijmegen
Radboud Universiteit
Orrú, Emanuela
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Netherlands, Nijmegen
Radboud Universiteit
Pizzo, Roberto F.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Anderson, James M.
Germany, Bonn
Max Planck Institute for Radio Astronomy
Beck, Rainer
Germany, Bonn
Max Planck Institute for Radio Astronomy
Bell, Michael R.
Germany, Garching Bei Munchen
Max Planck Institute for Astrophysics
Bonafede, Annalisa
Germany, Hamburg
Universität Hamburg
Chyz̊y, Krzysztof T.
Poland, Krakow
Uniwersytet Jagielloński
Dettmar, Ralf Juergen
Germany, Bochum
Ruhr-universitat Bochum
Ensslin, Torsten A.
Germany, Garching Bei Munchen
Max Planck Institute for Astrophysics
Heald, George H.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Horellou, Cathy
Sweden, Onsala
Onsala Space Observatory
Horneffer, Andreas
Germany, Bonn
Max Planck Institute for Radio Astronomy
Jurusik, Wojciech
Poland, Krakow
Uniwersytet Jagielloński
Junklewitz, H.
Germany, Garching Bei Munchen
Max Planck Institute for Astrophysics
Kuniyoshi, Masaya
Germany, Bonn
Max Planck Institute for Radio Astronomy
Mulcahy, D. D.
Germany, Bonn
Max Planck Institute for Radio Astronomy
Paladino, Rosita
Italy, Bologna
Alma Mater Studiorum Università Di Bologna
Reich, Wolfganga
Germany, Bonn
Max Planck Institute for Radio Astronomy
Scaife, Anna M.M.
United Kingdom, Southampton
University of Southampton
Sobey, Charlotte A.
Germany, Bonn
Max Planck Institute for Radio Astronomy
Sotomayor-Beltran, C. A.
Germany, Bochum
Ruhr-universitat Bochum
Alexov, Anastasia
United States, Baltimore
Space Telescope Science Institute
Asgekar, Ashish
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Avruch, Ian Max
Netherlands, Utrecht
Sron Netherlands Institute for Space Research
Bell, Martin E.
Australia, Sydney
The University of Sydney
van Bemmel, Ilse M.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Bentum, Mark J.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Bernardi, Gianni
United States, Cambridge
Harvard-smithsonian Center for Astrophysics
Best, Phillip N.
United Kingdom, Edinburgh
University of Edinburgh, Institute for Astronomy
Bi̊rzan, Laura
Netherlands, Leiden
Sterrewacht Leiden
Breitling, Frank
Germany, Potsdam
Leibniz Institute for Astrophysics Potsdam
Broderick, Jess W.
United Kingdom, Southampton
University of Southampton
Brouw, Willem N.
Netherlands, Groningen
Kapteyn Instituut
Brüggen, Marcus
Germany, Hamburg
Universität Hamburg
Butcher, Harvey R.
Australia, Canberra
Australian National University, Mount Stromlo Observatory
Ciardi, Benedetta
Germany, Garching Bei Munchen
Max Planck Institute for Astrophysics
Conway, John E.
Sweden, Onsala
Onsala Space Observatory
De Gasperin, Francesco
Germany, Hamburg
Universität Hamburg
de Geus, Eugène J.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Duscha, Sven
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Eislöffel, Jochen
Germany, Camburg
Thüringer Landessternwarte
Engels, Dieter
Germany, Hamburg
Universität Hamburg
Falcke, Heino D.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Netherlands, Nijmegen
Radboud Universiteit
Fallows, Richard A.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Ferrari, Chiara
France, Nice
Laboratoire Joseph-louis Lagrange
Frieswijk, Wilfred W.F.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Garrett, Michael A.
Netherlands, Leiden
Sterrewacht Leiden
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Grießmeier, Jean Mathias
France, Orleans
Laboratoire de Physique et de Chimie de L'environnement et de L'espace Lpc2e
Gunst, André W.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Hamaker, Johan P.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Hassall, Tom E.
United Kingdom, Southampton
University of Southampton
United Kingdom, Manchester
The University of Manchester
Hessels, Jason W.T.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Netherlands, Amsterdam
Anton Pannekoek Instituut Voor Sterrenkunde
Hoeft, Matthias
Germany, Camburg
Thüringer Landessternwarte
Hörandel, Jörg R.
Netherlands, Nijmegen
Radboud Universiteit
Jelić, Vibor
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Karastergiou, Aris
United Kingdom, Oxford
University of Oxford
Kondratiev, Vladislav I.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Russian Federation, Moscow
P.n. Lebedev Physical Institute of the Russian Academy of Sciences
Koopmans, Léon V.E.
Netherlands, Groningen
Kapteyn Instituut
Kramer, Michael
Germany, Bonn
Max Planck Institute for Radio Astronomy
Kuper, G.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
van Leeuwen, Joeri
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
MacArio, Giulia
France, Nice
Laboratoire Joseph-louis Lagrange
Mann, Gottfried J.
Germany, Potsdam
Leibniz Institute for Astrophysics Potsdam
McKean, John P.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Munk, H.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Pandey-Pommier, Mamta
France, Saint-genis-laval
Centre de Recherche Astrophysique de Lyon
Polatidis, Antonios G.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
R̈ottgering, Huub J.A.R.
Netherlands, Leiden
Sterrewacht Leiden
Schwarz, Dominik J.
Germany, Bielefeld
Universität Bielefeld
Sluman, J. J.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Smirnov, Oleg M.
South Africa, Grahamstown
Rhodes University
South Africa, Pinelands
Square Kilometre Array, South Africa
Stappers, Benjamin W.
United Kingdom, Manchester
The University of Manchester
Steinmetz, Matthias
Germany, Potsdam
Leibniz Institute for Astrophysics Potsdam
Tagger, Michel
France, Orleans
Laboratoire de Physique et de Chimie de L'environnement et de L'espace Lpc2e
Tang, Y.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Tasse, Cyril
France, Paris
L'observatoire de Paris
Toribio, C.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Vermeulen, René C.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Vocks, Christian
Germany, Potsdam
Leibniz Institute for Astrophysics Potsdam
Vogt, Corina
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
van Weeren, Reinout J.
United States, Cambridge
Harvard-smithsonian Center for Astrophysics
Wise, Michael W.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Netherlands, Amsterdam
Anton Pannekoek Instituut Voor Sterrenkunde
Wucknitz, Olaf
Germany, Bonn
Max Planck Institute for Radio Astronomy
Germany, Bonn
Universität Bonn
Yatawatta, Sarod B.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Zarka, Philippe M.
France, Paris
L'observatoire de Paris
Zensus, Anton J.
Germany, Bonn
Max Planck Institute for Radio Astronomy
Statistics
Citations: 88
Authors: 88
Affiliations: 32
Identifiers
Doi:
10.1051/0004-6361/201322013
ISSN:
00046361
e-ISSN:
14320746
Research Areas
Environmental