Skip Navigation

Discovery of carbon radio recombination lines in absorption towards Cygnus A

  1. A. Zensus8
  1. 1Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, NL-7990 AA Dwingeloo, the Netherlands
  2. 2Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
  3. 3Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
  4. 4Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
  5. 5RAL Space, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK
  6. 6Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
  7. 7Astronomical Institute ‘Anton Pannekoek’, University of Amsterdam, Postbus 94249, NL-1090 GE Amsterdam, the Netherlands
  8. 8Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
  9. 9SRON Netherlands Insitute for Space Research, PO Box 800, NL-9700 AV Groningen, the Netherlands
  10. 10Onsala Space Observatory, Department of Earth and Space Sciences, Chalmers University of Technology, SE-43992 Onsala, Sweden
  11. 11ARC Centre of Excellence for All-sky astrophysics (CAASTRO), Sydney Institute of Astronomy, University of Sydney, NSW 2006 Sydney, Australia
  12. 12Centre for Radio Astronomy Techniques and Technologies (RATT), Department of Physics and Electronics, Rhodes University, PO Box 94, Grahamstown 6140, South Africa
  13. 13SKA South Africa, 3rd Floor, The Park, Park Road, Pinelands 7405, South Africa
  14. 14Institute for Astronomy, University of Edinburgh, Royal Observatory of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
  15. 15University of Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany
  16. 16Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany
  17. 17School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK
  18. 18Research School of Astronomy and Astrophysics, Australian National University, Mt Stromlo Obs., via Cotter Road, Weston, ACT 2611, Australia
  19. 19Max Planck Institute for Astrophysics, Karl Schwarzschild Str. 1, D-85741 Garching, Germany
  20. 20Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, NL-6500 GL Nijmegen, the Netherlands
  21. 21Thüringer Landessternwarte, Sternwarte 5, D-07778 Tautenburg, Germany
  22. 22Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg, Germany
  23. 23Laboratoire Lagrange, UMR7293, Universitè de Nice Sophia-Antipolis, CNRS, Observatoire de la Cóte d'Azur, F-06300 Nice, France
  24. 24Laboratoire de Physique et Chimie de l’ Environnement et de l’ Espace, LPC2E UMR 7328 CNRS, F-45071 Orléans Cedex 02, France
  25. 25Jodrell Bank Center for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK
  26. 26Astronomisches Institut der Ruhr-Universität Bochum, Universitaetsstrasse 150, D-44780 Bochum, Germany
  27. 27Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
  28. 28Astro Space Center of the Lebedev Physical Institute, Profsoyuznaya str. 84/32, Moscow 117997, Russia
  29. 29Kapteyn Astronomical Institute, PO Box 800, NL-9700 AV Groningen, the Netherlands
  30. 30International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
  31. 31Center for Information Technology (CIT), University of Groningen, NL-9700 CA Groningen, the Netherlands
  32. 32Centre de Recherche Astrophysique de Lyon, Observatoire de Lyon, 9 av Charles André, F-69561 Saint Genis Laval Cedex, France
  33. 33Fakultät fur Physik, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
  34. 34LESIA, UMR CNRS 8109, Observatoire de Paris, F-92195 Meudon, France
  35. 35Netherlands eScience Center, Science Park 140, NL-1098 XG Amsterdam, the Netherlands
  36. 36Argelander-Institut für Astronomie, University of Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany
  1. ↵★E-mail: oonk{at}strw.leidenuniv.nl
  • Accepted 2013 November 4.
  • Received 2013 October 30.
  • In original form 2013 September 10.
  • First published online December 6, 2013.

Abstract

We present the first detection of carbon radio recombination line absorption along the line of sight to Cygnus A. The observations were carried out with the Low Frequency Array in the 33–57 MHz range. These low-frequency radio observations provide us with a new line of sight to study the diffuse, neutral gas in our Galaxy. To our knowledge this is the first time that foreground Milky Way recombination line absorption has been observed against a bright extragalactic background source. By stacking 48 carbon α lines in the observed frequency range we detect carbon absorption with a signal-to-noise ratio of about 5. The average carbon absorption has a peak optical depth of 2 × 10−4, a line width of 10 km s−1 and a velocity of +4 km s−1 with respect to the local standard of rest. The associated gas is found to have an electron temperature Te ∼ 110 K and density ne ∼ 0.06 cm−3. These properties imply that the observed carbon α absorption likely arises in the cold neutral medium of the Orion arm of the Milky Way. Hydrogen and helium lines were not detected to a 3σ peak optical depth limit of 1.5 × 10−4 for a 4 km s−1 channel width. Radio recombination lines associated with Cygnus A itself were also searched for, but are not detected. We set a 3σ upper limit of 1.5 × 10−4 for the peak optical depth of these lines for a 4 km s−1 channel width.

Key words

| Table of Contents

This Article

  1. MNRAS 437 (4): 3506-3515. doi: 10.1093/mnras/stt2158 First published online December 6, 2013
  1. » AbstractFree
  2. Full Text (HTML)
  3. Full Text (PDF)
  4. All Versions of this Article:
    1. stt2158v1
    2. 437/4/3506 most recent

Classifications

Astrophysics Data System

  1. ADS Abstract
  2. Articles by Oonk, J. B. R.
  3. Articles by van Weeren, R. J.
  4. Articles by Salgado, F.
  5. Articles by Morabito, L. K.
  6. Articles by Tielens, A. G. G. M.
  7. Articles by Rottgering, H. J. A.
  8. Articles by Asgekar, A.
  9. Articles by White, G. J.
  10. Articles by Alexov, A.
  11. Articles by Anderson, J.
  12. Articles by Avruch, I. M.
  13. Articles by Batejat, F.
  14. Articles by Beck, R.
  15. Articles by Bell, M. E.
  16. Articles by van Bemmel, I.
  17. Articles by Bentum, M. J.
  18. Articles by Bernardi, G.
  19. Articles by Best, P.
  20. Articles by Bonafede, A.
  21. Articles by Breitling, F.
  22. Articles by Brentjens, M.
  23. Articles by Broderick, J.
  24. Articles by Brüggen, M.
  25. Articles by Butcher, H. R.
  26. Articles by Ciardi, B.
  27. Articles by Conway, J. E.
  28. Articles by Corstanje, A.
  29. Articles by de Gasperin, F.
  30. Articles by de Geus, E.
  31. Articles by de Vos, M.
  32. Articles by Duscha, S.
  33. Articles by Eislöffel, J.
  34. Articles by Engels, D.
  35. Articles by van Enst, J.
  36. Articles by Falcke, H.
  37. Articles by Fallows, R. A.
  38. Articles by Fender, R.
  39. Articles by Ferrari, C.
  40. Articles by Frieswijk, W.
  41. Articles by Garrett, M. A.
  42. Articles by Grießmeier, J.
  43. Articles by Hamaker, J. P.
  44. Articles by Hassall, T. E.
  45. Articles by Heald, G.
  46. Articles by Hessels, J. W. T.
  47. Articles by Hoeft, M.
  48. Articles by Horneffer, A.
  49. Articles by Horst, A. van der
  50. Articles by Iacobelli, M.
  51. Articles by Jackson, N. J.
  52. Articles by Juette, E.
  53. Articles by Karastergiou, A.
  54. Articles by Klijn, W.
  55. Articles by Kohler, J.
  56. Articles by Kondratiev, V. I.
  57. Articles by Kramer, M.
  58. Articles by Kuniyoshi, M.
  59. Articles by Kuper, G.
  60. Articles by van Leeuwen, J.
  61. Articles by Maat, P.
  62. Articles by Macario, G.
  63. Articles by Mann, G.
  64. Articles by Markoff, S.
  65. Articles by McKean, J. P.
  66. Articles by Mevius, M.
  67. Articles by Miller-Jones, J. C. A.
  68. Articles by Mol, J. D.
  69. Articles by Mulcahy, D. D.
  70. Articles by Munk, H.
  71. Articles by Norden, M. J.
  72. Articles by Orru, E.
  73. Articles by Paas, H.
  74. Articles by Pandey-Pommier, M.
  75. Articles by Pandey, V. N.
  76. Articles by Pizzo, R.
  77. Articles by Polatidis, A. G.
  78. Articles by Reich, W.
  79. Articles by Scaife, A. M. M.
  80. Articles by Schoenmakers, A.
  81. Articles by Schwarz, D.
  82. Articles by Shulevski, A.
  83. Articles by Sluman, J.
  84. Articles by Smirnov, O.
  85. Articles by Sobey, C.
  86. Articles by Stappers, B. W.
  87. Articles by Steinmetz, M.
  88. Articles by Swinbank, J.
  89. Articles by Tagger, M.
  90. Articles by Tang, Y.
  91. Articles by Tasse, C.
  92. Articles by Veen, S. ter
  93. Articles by Thoudam, S.
  94. Articles by Toribio, C.
  95. Articles by van Nieuwpoort, R.
  96. Articles by Vermeulen, R.
  97. Articles by Vocks, C.
  98. Articles by Vogt, C.
  99. Articles by Wijers, R. A. M. J.
  100. Articles by Wise, M. W.
  101. Articles by Wucknitz, O.
  102. Articles by Yatawatta, S.
  103. Articles by Zarka, P.
  104. Articles by Zensus, A.

Share

  1. Email this article

Current Content

  1. Volume 449 Issue 4 June 01, 2015
  1. MNRAS
  1. Alert me to new content

Companion title: MNRAS Letters

You are viewing MNRAS - switch to MNRAS Letters.

MNRAS Letters

The Journal

Impact Factor 5.226

5-Yr impact factor: 4.790

Published on behalf of

Royal Astronomical Society

Editor-in-Chief

D. R. Flower

For Authors

Open Access options for Authors - visit Oxford Open

Powered by MathJax

RCUK

Corporate Services

Alerting Services

Most

Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.