LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A

LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A

Cassiopeia A was observed using the low-band antennas of the LOw Frequency ARray (LOFAR) with high spectral resolution. This allowed a search for radio recombination lines (RRLs) along the line-of-sight to this source. Five carbon a RRLs were detected in absorption between 40 and 50 MHz with a signa...

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Main Authors: Asgekar, A., Oonk, J., Yatawatta, S., van Weeren, R., McKean, J., White, G., Jackson, N., Anderson, J., Avruch, I., Batejat, F., Beck, R., Bell, M., van Bemmel, I., Bentum, M., BERNARDI, G., Best, P., Birzan, L., Bonafede, A., Braun, R., Breitling, F., van de Brink, R., Broderick, J., Brouw, W., Brueggen, M., Butcher, H., van Cappellen, W., Ciardi, B., Conway, J., de Gasperin, F., de Geus, E., de Jong, A., de Vos, M., Duscha, S., Eisloeffel, J., Falcke, H., Fallows, R., Ferrari, C., Frieswijk, W., Garrett, M., Griessmeier, J., Grit, T., Gunst, A., Hassall, T., Heald, G., Hessels, J., Hoeft, M., Iacobelli, M., Intema, H., Juette, E., Karastergiou, A., Kohler, J., Kondratiev, V., Kuniyoshi, M., Kuper, G., Law, C., van Leeuwen, J., Maat, P., Macario, G., Mann, G., Markoff, S., McKay-Bukowski, D., Mevius, M., Miller-Jones, James, Mol, J., Morganti, R., Mulcahy, D., Munk, H., Norden, M., Orru, E., Paas, H., Pandey-Pommier, M., Pandey, V., Pizzo, R., Polatidis, A., Reich, W., Roettgering, H., Scheers, B., Schoenmakers, A., Sluman, J., Smirnov, O., Sobey, C., Steinmetz, M., Tagger, M., Tang, Y., Tasse, C., Vermeulen, R., Vocks, C., Wijers, R., Wise, M., Wucknitz, O., Zarka, P.
Format: Journal Article
Published: EDP Sciences 2013
Subjects:
ISM: individual objects: Cassiopeia A
ISM: clouds
radio lines: ISM
Online Access:http://www.aanda.org/articles/aa/abs/2013/03/aa21001-12/aa21001-12.html
http://hdl.handle.net/20.500.11937/8685
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author Asgekar, A.
Oonk, J.
Yatawatta, S.
van Weeren, R.
McKean, J.
White, G.
Jackson, N.
Anderson, J.
Avruch, I.
Batejat, F.
Beck, R.
Bell, M.
Bell, M.
van Bemmel, I.
Bentum, M.
BERNARDI, G.
Best, P.
Birzan, L.
Bonafede, A.
Braun, R.
Breitling, F.
van de Brink, R.
Broderick, J.
Brouw, W.
Brueggen, M.
Butcher, H.
van Cappellen, W.
Ciardi, B.
Conway, J.
de Gasperin, F.
de Geus, E.
de Jong, A.
de Vos, M.
Duscha, S.
Eisloeffel, J.
Falcke, H.
Fallows, R.
Ferrari, C.
Frieswijk, W.
Garrett, M.
Griessmeier, J.
Grit, T.
Gunst, A.
Hassall, T.
Heald, G.
Hessels, J.
Hoeft, M.
Iacobelli, M.
Intema, H.
Juette, E.
Karastergiou, A.
Kohler, J.
Kondratiev, V.
Kuniyoshi, M.
Kuper, G.
Law, C.
van Leeuwen, J.
Maat, P.
Macario, G.
Mann, G.
Markoff, S.
McKay-Bukowski, D.
Mevius, M.
Miller-Jones, James
Mol, J.
Morganti, R.
Mulcahy, D.
Munk, H.
Norden, M.
Orru, E.
Paas, H.
Pandey-Pommier, M.
Pandey, V.
Pizzo, R.
Polatidis, A.
Reich, W.
Roettgering, H.
Scheers, B.
Schoenmakers, A.
Sluman, J.
Smirnov, O.
Sobey, C.
Steinmetz, M.
Tagger, M.
Tang, Y.
Tasse, C.
Vermeulen, R.
Vocks, C.
Wijers, R.
Wise, M.
Wucknitz, O.
Zarka, P.
author_facet Asgekar, A.
Oonk, J.
Yatawatta, S.
van Weeren, R.
McKean, J.
White, G.
Jackson, N.
Anderson, J.
Avruch, I.
Batejat, F.
Beck, R.
Bell, M.
Bell, M.
van Bemmel, I.
Bentum, M.
BERNARDI, G.
Best, P.
Birzan, L.
Bonafede, A.
Braun, R.
Breitling, F.
van de Brink, R.
Broderick, J.
Brouw, W.
Brueggen, M.
Butcher, H.
van Cappellen, W.
Ciardi, B.
Conway, J.
de Gasperin, F.
de Geus, E.
de Jong, A.
de Vos, M.
Duscha, S.
Eisloeffel, J.
Falcke, H.
Fallows, R.
Ferrari, C.
Frieswijk, W.
Garrett, M.
Griessmeier, J.
Grit, T.
Gunst, A.
Hassall, T.
Heald, G.
Hessels, J.
Hoeft, M.
Iacobelli, M.
Intema, H.
Juette, E.
Karastergiou, A.
Kohler, J.
Kondratiev, V.
Kuniyoshi, M.
Kuper, G.
Law, C.
van Leeuwen, J.
Maat, P.
Macario, G.
Mann, G.
Markoff, S.
McKay-Bukowski, D.
Mevius, M.
Miller-Jones, James
Mol, J.
Morganti, R.
Mulcahy, D.
Munk, H.
Norden, M.
Orru, E.
Paas, H.
Pandey-Pommier, M.
Pandey, V.
Pizzo, R.
Polatidis, A.
Reich, W.
Roettgering, H.
Scheers, B.
Schoenmakers, A.
Sluman, J.
Smirnov, O.
Sobey, C.
Steinmetz, M.
Tagger, M.
Tang, Y.
Tasse, C.
Vermeulen, R.
Vocks, C.
Wijers, R.
Wise, M.
Wucknitz, O.
Zarka, P.
author_sort Asgekar, A.
building Curtin Institutional Repository
collection Online Access
description Cassiopeia A was observed using the low-band antennas of the LOw Frequency ARray (LOFAR) with high spectral resolution. This allowed a search for radio recombination lines (RRLs) along the line-of-sight to this source. Five carbon a RRLs were detected in absorption between 40 and 50 MHz with a signal-to-noise ratio of >5 from two independent LOFAR data sets. The derived line velocities (vLSR ~ - 50 km s-1) and integrated optical depths (~13 s-1) of the RRLs in our spectra, extracted over the whole supernova remnant, are consistent within each LOFAR data set and with those previously reported. For the first time, we are able to extract spectra against the brightest hotspot of the remnant at frequencies below 330 MHz. These spectra show significantly higher (15-80 percent) integrated optical depths, indicating that there is small-scale angular structure of the order of ~1 pc in the absorbing gas distribution over the face of the remnant. We also place an upper limit of 3 × 10-4 on the peak optical depths of hydrogen and helium RRLs. These results demonstrate that LOFAR has the desired spectral stability and sensitivity to study faint recombination lines in the decameter band.
first_indexed 2025-11-14T06:21:59Z
format Journal Article
id curtin-20.500.11937-8685
institution Curtin University Malaysia
institution_category Local University
last_indexed 2025-11-14T06:21:59Z
publishDate 2013
publisher EDP Sciences
recordtype eprints
repository_type Digital Repository
spelling curtin-20.500.11937-86852017-09-13T14:51:29Z LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A Asgekar, A. Oonk, J. Yatawatta, S. van Weeren, R. McKean, J. White, G. Jackson, N. Anderson, J. Avruch, I. Batejat, F. Beck, R. Bell, M. Bell, M. van Bemmel, I. Bentum, M. BERNARDI, G. Best, P. Birzan, L. Bonafede, A. Braun, R. Breitling, F. van de Brink, R. Broderick, J. Brouw, W. Brueggen, M. Butcher, H. van Cappellen, W. Ciardi, B. Conway, J. de Gasperin, F. de Geus, E. de Jong, A. de Vos, M. Duscha, S. Eisloeffel, J. Falcke, H. Fallows, R. Ferrari, C. Frieswijk, W. Garrett, M. Griessmeier, J. Grit, T. Gunst, A. Hassall, T. Heald, G. Hessels, J. Hoeft, M. Iacobelli, M. Intema, H. Juette, E. Karastergiou, A. Kohler, J. Kondratiev, V. Kuniyoshi, M. Kuper, G. Law, C. van Leeuwen, J. Maat, P. Macario, G. Mann, G. Markoff, S. McKay-Bukowski, D. Mevius, M. Miller-Jones, James Mol, J. Morganti, R. Mulcahy, D. Munk, H. Norden, M. Orru, E. Paas, H. Pandey-Pommier, M. Pandey, V. Pizzo, R. Polatidis, A. Reich, W. Roettgering, H. Scheers, B. Schoenmakers, A. Sluman, J. Smirnov, O. Sobey, C. Steinmetz, M. Tagger, M. Tang, Y. Tasse, C. Vermeulen, R. Vocks, C. Wijers, R. Wise, M. Wucknitz, O. Zarka, P. ISM: individual objects: Cassiopeia A ISM: clouds radio lines: ISM Cassiopeia A was observed using the low-band antennas of the LOw Frequency ARray (LOFAR) with high spectral resolution. This allowed a search for radio recombination lines (RRLs) along the line-of-sight to this source. Five carbon a RRLs were detected in absorption between 40 and 50 MHz with a signal-to-noise ratio of >5 from two independent LOFAR data sets. The derived line velocities (vLSR ~ - 50 km s-1) and integrated optical depths (~13 s-1) of the RRLs in our spectra, extracted over the whole supernova remnant, are consistent within each LOFAR data set and with those previously reported. For the first time, we are able to extract spectra against the brightest hotspot of the remnant at frequencies below 330 MHz. These spectra show significantly higher (15-80 percent) integrated optical depths, indicating that there is small-scale angular structure of the order of ~1 pc in the absorbing gas distribution over the face of the remnant. We also place an upper limit of 3 × 10-4 on the peak optical depths of hydrogen and helium RRLs. These results demonstrate that LOFAR has the desired spectral stability and sensitivity to study faint recombination lines in the decameter band. 2013 Journal Article http://hdl.handle.net/20.500.11937/8685 10.1051/0004-6361/201221001 http://www.aanda.org/articles/aa/abs/2013/03/aa21001-12/aa21001-12.html EDP Sciences fulltext
spellingShingle ISM: individual objects: Cassiopeia A
ISM: clouds
radio lines: ISM
Asgekar, A.
Oonk, J.
Yatawatta, S.
van Weeren, R.
McKean, J.
White, G.
Jackson, N.
Anderson, J.
Avruch, I.
Batejat, F.
Beck, R.
Bell, M.
Bell, M.
van Bemmel, I.
Bentum, M.
BERNARDI, G.
Best, P.
Birzan, L.
Bonafede, A.
Braun, R.
Breitling, F.
van de Brink, R.
Broderick, J.
Brouw, W.
Brueggen, M.
Butcher, H.
van Cappellen, W.
Ciardi, B.
Conway, J.
de Gasperin, F.
de Geus, E.
de Jong, A.
de Vos, M.
Duscha, S.
Eisloeffel, J.
Falcke, H.
Fallows, R.
Ferrari, C.
Frieswijk, W.
Garrett, M.
Griessmeier, J.
Grit, T.
Gunst, A.
Hassall, T.
Heald, G.
Hessels, J.
Hoeft, M.
Iacobelli, M.
Intema, H.
Juette, E.
Karastergiou, A.
Kohler, J.
Kondratiev, V.
Kuniyoshi, M.
Kuper, G.
Law, C.
van Leeuwen, J.
Maat, P.
Macario, G.
Mann, G.
Markoff, S.
McKay-Bukowski, D.
Mevius, M.
Miller-Jones, James
Mol, J.
Morganti, R.
Mulcahy, D.
Munk, H.
Norden, M.
Orru, E.
Paas, H.
Pandey-Pommier, M.
Pandey, V.
Pizzo, R.
Polatidis, A.
Reich, W.
Roettgering, H.
Scheers, B.
Schoenmakers, A.
Sluman, J.
Smirnov, O.
Sobey, C.
Steinmetz, M.
Tagger, M.
Tang, Y.
Tasse, C.
Vermeulen, R.
Vocks, C.
Wijers, R.
Wise, M.
Wucknitz, O.
Zarka, P.
LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A
title LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A
title_full LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A
title_fullStr LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A
title_full_unstemmed LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A
title_short LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A
title_sort lofar detections of low-frequency radio recombination lines towards cassiopeia a
topic ISM: individual objects: Cassiopeia A
ISM: clouds
radio lines: ISM
url http://www.aanda.org/articles/aa/abs/2013/03/aa21001-12/aa21001-12.html
http://hdl.handle.net/20.500.11937/8685

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