Discovery of carbon radio recombination lines in absorption towards Cygnus A

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 33–57MHz range. These low-frequency radio observations provide us with a new line of sight to study the diffuse,...

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Main Authors:	Oonk, J., van Weeren, R., Salgado, F., Morabito, L., Tielens, A., Rottgering, H., Asgekar, A., White, G., Alexov, A., Anderson, J., Avruch, I., Batejat, F., Beck, R., Bell, M., van Bemmel, I., Bentum, M., BERNARDI, G., Best, P., Bonafede, A., Breitling, F., Brentjens, M., Broderick, J., Bruggen, M., Butcher, H., Ciardi, B., Conway, J., Corstanje, A., de Gasperin, F., de Geus, E., de Vos, M., Duscha, S., Eisloffel, J., Engels, D., van Enst, J., Falcke, H., Fallows, R., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M., Grießmeier, J., Hamaker, J., Hassall, T., Heald, G., Hessels, J., Hoeft, M., Horneffer, A., van der Horst, A., Iacobelli, M., Jackson, N., Juette, E., Karastergiou, A., Klijn, W., Kohler, J., Kondratiev, V., Kramer, M., Kuniyoshi, M., Kuper, G., van Leeuwen, J., Maat, P., Macario, G., Mann, G., Markoff, S., McKean, J., Mevius, M., Miller-Jones, James, Mol, J., Mulcahy, D., Munk, H., Norden, M., Orru, E., Paas, H., Pandey-Pommier, M., Pandey, V., Pizzo, R., Polatidis, A., Reich, W., Scaife, A., Schoenmakers, A., Schwarz, D., Shulevski, A., Sluman, J., Smirnov, O., Sobey, C., Stappers, B., Steinmetz, M., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., ter Veen, S., Thoudam, S., Toribio, C., van Nieuwpoort, R., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R., Wise, M., Wucknitz, O., Yatawatta, S., Zarka, P., Zensus, J.
Format:	Journal Article
Published:	Oxford University Press 2014
Subjects:	local interstellar matter ISM: structure ISM: general radio lines: ISM
Online Access:	http://hdl.handle.net/20.500.11937/3036

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author	Oonk, J. van Weeren, R. Salgado, F. Morabito, L. Tielens, A. Rottgering, H. Asgekar, A. White, G. Alexov, A. Anderson, J. Avruch, I. Batejat, F. Beck, R. Bell, M. van Bemmel, I. Bentum, M. BERNARDI, G. Best, P. Bonafede, A. Breitling, F. Brentjens, M. Broderick, J. Bruggen, M. Butcher, H. Ciardi, B. Conway, J. Corstanje, A. de Gasperin, F. de Geus, E. de Vos, M. Duscha, S. Eisloffel, J. Engels, D. van Enst, J. Falcke, H. Fallows, R. Fender, R. Ferrari, C. Frieswijk, W. Garrett, M. Grießmeier, J. Hamaker, J. Hassall, T. Heald, G. Hessels, J. Hoeft, M. Horneffer, A. van der Horst, A. Iacobelli, M. Jackson, N. Juette, E. Karastergiou, A. Klijn, W. Kohler, J. Kondratiev, V. Kramer, M. Kuniyoshi, M. Kuper, G. van Leeuwen, J. Maat, P. Macario, G. Mann, G. Markoff, S. McKean, J. Mevius, M. Miller-Jones, James Mol, J. Mulcahy, D. Munk, H. Norden, M. Orru, E. Paas, H. Pandey-Pommier, M. Pandey, V. Pizzo, R. Polatidis, A. Reich, W. Scaife, A. Schoenmakers, A. Schwarz, D. Shulevski, A. Sluman, J. Smirnov, O. Sobey, C. Stappers, B. Steinmetz, M. Swinbank, J. Tagger, M. Tang, Y. Tasse, C. ter Veen, S. Thoudam, S. Toribio, C. van Nieuwpoort, R. Vermeulen, R. Vocks, C. Vogt, C. Wijers, R. Wise, M. Wucknitz, O. Yatawatta, S. Zarka, P. Zensus, J.
author_facet	Oonk, J. van Weeren, R. Salgado, F. Morabito, L. Tielens, A. Rottgering, H. Asgekar, A. White, G. Alexov, A. Anderson, J. Avruch, I. Batejat, F. Beck, R. Bell, M. van Bemmel, I. Bentum, M. BERNARDI, G. Best, P. Bonafede, A. Breitling, F. Brentjens, M. Broderick, J. Bruggen, M. Butcher, H. Ciardi, B. Conway, J. Corstanje, A. de Gasperin, F. de Geus, E. de Vos, M. Duscha, S. Eisloffel, J. Engels, D. van Enst, J. Falcke, H. Fallows, R. Fender, R. Ferrari, C. Frieswijk, W. Garrett, M. Grießmeier, J. Hamaker, J. Hassall, T. Heald, G. Hessels, J. Hoeft, M. Horneffer, A. van der Horst, A. Iacobelli, M. Jackson, N. Juette, E. Karastergiou, A. Klijn, W. Kohler, J. Kondratiev, V. Kramer, M. Kuniyoshi, M. Kuper, G. van Leeuwen, J. Maat, P. Macario, G. Mann, G. Markoff, S. McKean, J. Mevius, M. Miller-Jones, James Mol, J. Mulcahy, D. Munk, H. Norden, M. Orru, E. Paas, H. Pandey-Pommier, M. Pandey, V. Pizzo, R. Polatidis, A. Reich, W. Scaife, A. Schoenmakers, A. Schwarz, D. Shulevski, A. Sluman, J. Smirnov, O. Sobey, C. Stappers, B. Steinmetz, M. Swinbank, J. Tagger, M. Tang, Y. Tasse, C. ter Veen, S. Thoudam, S. Toribio, C. van Nieuwpoort, R. Vermeulen, R. Vocks, C. Vogt, C. Wijers, R. Wise, M. Wucknitz, O. Yatawatta, S. Zarka, P. Zensus, J.
author_sort	Oonk, J.
building	Curtin Institutional Repository
collection	Online Access
description	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 33–57MHz 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 a 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 kms-1 with respect to the local standard of rest. The associated gas is found to have an electron temperature Te ~ 110K and density ne ~ 0.06 cm-3. These properties imply that the observed carbon a 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 3s peak optical depth limit of 1.5 × 10-4 for a 4 kms-1 channel width. Radio recombination lines associated with Cygnus A itself were also searched for, but are not detected. We set a 3s upper limit of 1.5 × 10-4 for the peak optical depth of these lines for a 4 kms-1 channel width.
first_indexed	2025-11-14T05:56:24Z
format	Journal Article
id	curtin-20.500.11937-3036
institution	Curtin University Malaysia
institution_category	Local University
last_indexed	2025-11-14T05:56:24Z
publishDate	2014
publisher	Oxford University Press
recordtype	eprints
repository_type	Digital Repository
spelling	curtin-20.500.11937-30362017-09-13T14:32:14Z Discovery of carbon radio recombination lines in absorption towards Cygnus A Oonk, J. van Weeren, R. Salgado, F. Morabito, L. Tielens, A. Rottgering, H. Asgekar, A. White, G. Alexov, A. Anderson, J. Avruch, I. Batejat, F. Beck, R. Bell, M. van Bemmel, I. Bentum, M. BERNARDI, G. Best, P. Bonafede, A. Breitling, F. Brentjens, M. Broderick, J. Bruggen, M. Butcher, H. Ciardi, B. Conway, J. Corstanje, A. de Gasperin, F. de Geus, E. de Vos, M. Duscha, S. Eisloffel, J. Engels, D. van Enst, J. Falcke, H. Fallows, R. Fender, R. Ferrari, C. Frieswijk, W. Garrett, M. Grießmeier, J. Hamaker, J. Hassall, T. Heald, G. Hessels, J. Hoeft, M. Horneffer, A. van der Horst, A. Iacobelli, M. Jackson, N. Juette, E. Karastergiou, A. Klijn, W. Kohler, J. Kondratiev, V. Kramer, M. Kuniyoshi, M. Kuper, G. van Leeuwen, J. Maat, P. Macario, G. Mann, G. Markoff, S. McKean, J. Mevius, M. Miller-Jones, James Mol, J. Mulcahy, D. Munk, H. Norden, M. Orru, E. Paas, H. Pandey-Pommier, M. Pandey, V. Pizzo, R. Polatidis, A. Reich, W. Scaife, A. Schoenmakers, A. Schwarz, D. Shulevski, A. Sluman, J. Smirnov, O. Sobey, C. Stappers, B. Steinmetz, M. Swinbank, J. Tagger, M. Tang, Y. Tasse, C. ter Veen, S. Thoudam, S. Toribio, C. van Nieuwpoort, R. Vermeulen, R. Vocks, C. Vogt, C. Wijers, R. Wise, M. Wucknitz, O. Yatawatta, S. Zarka, P. Zensus, J. local interstellar matter ISM: structure ISM: general radio lines: ISM 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 33–57MHz 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 a 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 kms-1 with respect to the local standard of rest. The associated gas is found to have an electron temperature Te ~ 110K and density ne ~ 0.06 cm-3. These properties imply that the observed carbon a 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 3s peak optical depth limit of 1.5 × 10-4 for a 4 kms-1 channel width. Radio recombination lines associated with Cygnus A itself were also searched for, but are not detected. We set a 3s upper limit of 1.5 × 10-4 for the peak optical depth of these lines for a 4 kms-1 channel width. 2014 Journal Article http://hdl.handle.net/20.500.11937/3036 10.1093/mnras/stt2158 Oxford University Press fulltext
spellingShingle	local interstellar matter ISM: structure ISM: general radio lines: ISM Oonk, J. van Weeren, R. Salgado, F. Morabito, L. Tielens, A. Rottgering, H. Asgekar, A. White, G. Alexov, A. Anderson, J. Avruch, I. Batejat, F. Beck, R. Bell, M. van Bemmel, I. Bentum, M. BERNARDI, G. Best, P. Bonafede, A. Breitling, F. Brentjens, M. Broderick, J. Bruggen, M. Butcher, H. Ciardi, B. Conway, J. Corstanje, A. de Gasperin, F. de Geus, E. de Vos, M. Duscha, S. Eisloffel, J. Engels, D. van Enst, J. Falcke, H. Fallows, R. Fender, R. Ferrari, C. Frieswijk, W. Garrett, M. Grießmeier, J. Hamaker, J. Hassall, T. Heald, G. Hessels, J. Hoeft, M. Horneffer, A. van der Horst, A. Iacobelli, M. Jackson, N. Juette, E. Karastergiou, A. Klijn, W. Kohler, J. Kondratiev, V. Kramer, M. Kuniyoshi, M. Kuper, G. van Leeuwen, J. Maat, P. Macario, G. Mann, G. Markoff, S. McKean, J. Mevius, M. Miller-Jones, James Mol, J. Mulcahy, D. Munk, H. Norden, M. Orru, E. Paas, H. Pandey-Pommier, M. Pandey, V. Pizzo, R. Polatidis, A. Reich, W. Scaife, A. Schoenmakers, A. Schwarz, D. Shulevski, A. Sluman, J. Smirnov, O. Sobey, C. Stappers, B. Steinmetz, M. Swinbank, J. Tagger, M. Tang, Y. Tasse, C. ter Veen, S. Thoudam, S. Toribio, C. van Nieuwpoort, R. Vermeulen, R. Vocks, C. Vogt, C. Wijers, R. Wise, M. Wucknitz, O. Yatawatta, S. Zarka, P. Zensus, J. Discovery of carbon radio recombination lines in absorption towards Cygnus A
title	Discovery of carbon radio recombination lines in absorption towards Cygnus A
title_full	Discovery of carbon radio recombination lines in absorption towards Cygnus A
title_fullStr	Discovery of carbon radio recombination lines in absorption towards Cygnus A
title_full_unstemmed	Discovery of carbon radio recombination lines in absorption towards Cygnus A
title_short	Discovery of carbon radio recombination lines in absorption towards Cygnus A
title_sort	discovery of carbon radio recombination lines in absorption towards cygnus a
topic	local interstellar matter ISM: structure ISM: general radio lines: ISM
url	http://hdl.handle.net/20.500.11937/3036

Discovery of carbon radio recombination lines in absorption towards Cygnus A

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