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

A. Asgekar; J.B.R. Oonk; S. Yatawatta; R.J. van Weeren; J.P. McKean; G. White; N. Jackson; J. Anderson; I.M. Avruch; F. Batejat; R. Beck; M.E. Bell; M.R. Bell; I. van Bemmel; Marinus Jan Bentum; G. Bernardi; P. Best; L. Birzan; A. Bonafede; R. Braun; F. Breitling; R.H. van de Brink; J. Broderick; W.N. Brouw; M. Brüggen; H.R. Butcher; W. van Capellen; B. Ciardi; J.E. Conway; F. de Gasperin; E. de Geus; A. de Jong; M. Vos; S. Duscha; J. Eislöffel; H. Falcke; R.A. Fallows; C. Ferrari; W. Frieswijk; M.A. Garrett; J.M. Griessmeier; T. Grit; A.W. Gunst; T.E. Hassall; G. Heald; J.W.T. Hessels; M. Hoeft; M. Iacobelli; H. Intema; E. Juette; A. Karastergiou; J Kohler; V.I. Kondratiev; M. Kuniyoshi; G. Kuper; C. Law; J. van Leeuwen; P. Maat; G. Macario; G. Mann; S. Markoff; D. McKay-Bukowski; M. Mevius; J.C.A Miller-Jones; J.D. Mol; R. Morganti; D.D. Mulcahy; H. Munk; M.J. Norden; E. Orrú; H. Paas; M. Pandey-Pommier; V.N. Pandey; R. Pizzo; A.G. Polatidis; W. Reich; H. Röttgering; B. Scheers; A. Schoenmakers; J. Sluman; O. Smirnov; C. Sobey; M. Steinmetz; M. Tagger; Y. Tang; C. Tasse; R. Vermeulen; C. Vocks; R.A.M.J. Wijers; M.W. Wise; O. Wucknitz; P. Zarka

doi:10.1051/0004-6361/201221001

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

A. Asgekar, J.B.R. Oonk, S. Yatawatta, R.J. van Weeren, J.P. McKean, G. White, N. Jackson, J. Anderson, I.M. Avruch, F. Batejat, R. Beck, M.E. Bell, M.R. Bell, I. van Bemmel, Marinus Jan Bentum, G. Bernardi, P. Best, L. Birzan, A. Bonafede, R. BraunF. Breitling, R.H. van de Brink, J. Broderick, W.N. Brouw, M. Brüggen, H.R. Butcher, W. van Capellen, B. Ciardi, J.E. Conway, F. de Gasperin, E. de Geus, A. de Jong, M. Vos, S. Duscha, J. Eislöffel, H. Falcke, R.A. Fallows, C. Ferrari, W. Frieswijk, M.A. Garrett, J.M. Griessmeier, T. Grit, A.W. Gunst, T.E. Hassall, G. Heald, J.W.T. Hessels, M. Hoeft, M. Iacobelli, H. Intema, E. Juette, A. Karastergiou, J Kohler, V.I. Kondratiev, M. Kuniyoshi, G. Kuper, C. Law, J. van Leeuwen, P. Maat, G. Macario, G. Mann, S. Markoff, D. McKay-Bukowski, M. Mevius, J.C.A Miller-Jones, J.D. Mol, R. Morganti, D.D. Mulcahy, H. Munk, M.J. Norden, E. Orrú, H. Paas, M. Pandey-Pommier, V.N. Pandey, R. Pizzo, A.G. Polatidis, W. Reich, H. Röttgering, B. Scheers, A. Schoenmakers, J. Sluman, O. Smirnov, C. Sobey, M. Steinmetz, M. Tagger, Y. Tang, C. Tasse, R. Vermeulen, C. Vocks, R.A.M.J. Wijers, M.W. Wise, O. Wucknitz, P. Zarka

Research output: Contribution to journal › Article › Academic › peer-review

12 Citations (Scopus)

Abstract

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 α 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.

Original language	Undefined
Pages (from-to)	1-5
Number of pages	5
Journal	Astronomy & astrophysics
Volume	551
Issue number	L11
DOIs	https://doi.org/10.1051/0004-6361/201221001
Publication status	Published - 28 Feb 2013

Keywords

EWI-24495
IR-89496
METIS-302711
ISM: clouds / radio lines: ISM / ISM: individual objects: Cassiopeia A

Access to Document

10.1051/0004-6361/201221001

http://eprints.eemcs.utwente.nl/secure2/24495/01/aa21001-12.pdf

Cite this

Asgekar, A., Oonk, J. B. R., Yatawatta, S., van Weeren, R. J., McKean, J. P., White, G., Jackson, N., Anderson, J., Avruch, I. M., Batejat, F., Beck, R., Bell, M. E., Bell, M. R., van Bemmel, I., Bentum, M. J., Bernardi, G., Best, P., Birzan, L., Bonafede, A., ... Zarka, P. (2013). LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A. Astronomy & astrophysics, 551(L11), 1-5. https://doi.org/10.1051/0004-6361/201221001

Asgekar, A. ; Oonk, J.B.R. ; Yatawatta, S. ; van Weeren, R.J. ; McKean, J.P. ; White, G. ; Jackson, N. ; Anderson, J. ; Avruch, I.M. ; Batejat, F. ; Beck, R. ; Bell, M.E. ; Bell, M.R. ; van Bemmel, I. ; Bentum, Marinus Jan ; Bernardi, G. ; Best, P. ; Birzan, L. ; Bonafede, A. ; Braun, R. ; Breitling, F. ; van de Brink, R.H. ; Broderick, J. ; Brouw, W.N. ; Brüggen, M. ; Butcher, H.R. ; van Capellen, W. ; Ciardi, B. ; Conway, J.E. ; de Gasperin, F. ; de Geus, E. ; de Jong, A. ; Vos, M. ; Duscha, S. ; Eislöffel, J. ; Falcke, H. ; Fallows, R.A. ; Ferrari, C. ; Frieswijk, W. ; Garrett, M.A. ; Griessmeier, J.M. ; Grit, T. ; Gunst, A.W. ; Hassall, T.E. ; Heald, G. ; Hessels, J.W.T. ; Hoeft, M. ; Iacobelli, M. ; Intema, H. ; Juette, E. ; Karastergiou, A. ; Kohler, J ; Kondratiev, V.I. ; Kuniyoshi, M. ; Kuper, G. ; Law, C. ; van Leeuwen, J. ; Maat, P. ; Macario, G. ; Mann, G. ; Markoff, S. ; McKay-Bukowski, D. ; Mevius, M. ; Miller-Jones, J.C.A ; Mol, J.D. ; Morganti, R. ; Mulcahy, D.D. ; Munk, H. ; Norden, M.J. ; Orrú, E. ; Paas, H. ; Pandey-Pommier, M. ; Pandey, V.N. ; Pizzo, R. ; Polatidis, A.G. ; Reich, W. ; Röttgering, 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.A.M.J. ; Wise, M.W. ; Wucknitz, O. ; Zarka, P. / LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A. In: Astronomy & astrophysics. 2013 ; Vol. 551, No. L11. pp. 1-5.

@article{7070fb2fcc404202a80a4c9feede2299,

title = "LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A",

abstract = "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 α 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.",

keywords = "EWI-24495, IR-89496, METIS-302711, ISM: clouds / radio lines: ISM / ISM: individual objects: Cassiopeia A",

author = "A. Asgekar and J.B.R. Oonk and S. Yatawatta and {van Weeren}, R.J. and J.P. McKean and G. White and N. Jackson and J. Anderson and I.M. Avruch and F. Batejat and R. Beck and M.E. Bell and M.R. Bell and {van Bemmel}, I. and Bentum, {Marinus Jan} and G. Bernardi and P. Best and L. Birzan and A. Bonafede and R. Braun and F. Breitling and {van de Brink}, R.H. and J. Broderick and W.N. Brouw and M. Br{\"u}ggen and H.R. Butcher and {van Capellen}, W. and B. Ciardi and J.E. Conway and {de Gasperin}, F. and {de Geus}, E. and {de Jong}, A. and M. Vos and S. Duscha and J. Eisl{\"o}ffel and H. Falcke and R.A. Fallows and C. Ferrari and W. Frieswijk and M.A. Garrett and J.M. Griessmeier and T. Grit and A.W. Gunst and T.E. Hassall and G. Heald and J.W.T. Hessels and M. Hoeft and M. Iacobelli and H. Intema and E. Juette and A. Karastergiou and J Kohler and V.I. Kondratiev and M. Kuniyoshi and G. Kuper and C. Law and {van Leeuwen}, J. and P. Maat and G. Macario and G. Mann and S. Markoff and D. McKay-Bukowski and M. Mevius and J.C.A Miller-Jones and J.D. Mol and R. Morganti and D.D. Mulcahy and H. Munk and M.J. Norden and E. Orr{\'u} and H. Paas and M. Pandey-Pommier and V.N. Pandey and R. Pizzo and A.G. Polatidis and W. Reich and H. R{\"o}ttgering and B. Scheers and A. Schoenmakers and J. Sluman and O. Smirnov and C. Sobey and M. Steinmetz and M. Tagger and Y. Tang and C. Tasse and R. Vermeulen and C. Vocks and R.A.M.J. Wijers and M.W. Wise and O. Wucknitz and P. Zarka",

note = "eemcs-eprint-24495 ",

year = "2013",

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doi = "10.1051/0004-6361/201221001",

language = "Undefined",

volume = "551",

pages = "1--5",

journal = "Astronomy & astrophysics",

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Asgekar, A, Oonk, JBR, Yatawatta, S, van Weeren, RJ, McKean, JP, White, G, Jackson, N, Anderson, J, Avruch, IM, Batejat, F, Beck, R, Bell, ME, Bell, MR, van Bemmel, I, Bentum, MJ, Bernardi, G, Best, P, Birzan, L, Bonafede, A, Braun, R, Breitling, F, van de Brink, RH, Broderick, J, Brouw, WN, Brüggen, M, Butcher, HR, van Capellen, W, Ciardi, B, Conway, JE, de Gasperin, F, de Geus, E, de Jong, A, Vos, M, Duscha, S, Eislöffel, J, Falcke, H, Fallows, RA, Ferrari, C, Frieswijk, W, Garrett, MA, Griessmeier, JM, Grit, T, Gunst, AW, Hassall, TE, Heald, G, Hessels, JWT, Hoeft, M, Iacobelli, M, Intema, H, Juette, E, Karastergiou, A, Kohler, J, Kondratiev, VI, Kuniyoshi, M, Kuper, G, Law, C, van Leeuwen, J, Maat, P, Macario, G, Mann, G, Markoff, S, McKay-Bukowski, D, Mevius, M, Miller-Jones, JCA, Mol, JD, Morganti, R, Mulcahy, DD, Munk, H, Norden, MJ, Orrú, E, Paas, H, Pandey-Pommier, M, Pandey, VN, Pizzo, R, Polatidis, AG, Reich, W, Röttgering, H, Scheers, B, Schoenmakers, A, Sluman, J, Smirnov, O, Sobey, C, Steinmetz, M, Tagger, M, Tang, Y, Tasse, C, Vermeulen, R, Vocks, C, Wijers, RAMJ, Wise, MW, Wucknitz, O & Zarka, P 2013, 'LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A', Astronomy & astrophysics, vol. 551, no. L11, pp. 1-5. https://doi.org/10.1051/0004-6361/201221001

LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A. / Asgekar, A.; Oonk, J.B.R.; Yatawatta, S.; van Weeren, R.J.; McKean, J.P.; White, G.; Jackson, N.; Anderson, J.; Avruch, I.M.; Batejat, F.; Beck, R.; Bell, M.E.; Bell, M.R.; van Bemmel, I.; Bentum, Marinus Jan; Bernardi, G.; Best, P.; Birzan, L.; Bonafede, A.; Braun, R.; Breitling, F.; van de Brink, R.H.; Broderick, J.; Brouw, W.N.; Brüggen, M.; Butcher, H.R.; van Capellen, W.; Ciardi, B.; Conway, J.E.; de Gasperin, F.; de Geus, E.; de Jong, A.; Vos, M.; Duscha, S.; Eislöffel, J.; Falcke, H.; Fallows, R.A.; Ferrari, C.; Frieswijk, W.; Garrett, M.A.; Griessmeier, J.M.; Grit, T.; Gunst, A.W.; Hassall, T.E.; Heald, G.; Hessels, J.W.T.; Hoeft, M.; Iacobelli, M.; Intema, H.; Juette, E.; Karastergiou, A.; Kohler, J; Kondratiev, V.I.; Kuniyoshi, M.; Kuper, G.; Law, C.; van Leeuwen, J.; Maat, P.; Macario, G.; Mann, G.; Markoff, S.; McKay-Bukowski, D.; Mevius, M.; Miller-Jones, J.C.A; Mol, J.D.; Morganti, R.; Mulcahy, D.D.; Munk, H.; Norden, M.J.; Orrú, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V.N.; Pizzo, R.; Polatidis, A.G.; Reich, W.; Röttgering, 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.A.M.J.; Wise, M.W.; Wucknitz, O.; Zarka, P.

In: Astronomy & astrophysics, Vol. 551, No. L11, 28.02.2013, p. 1-5.

Research output: Contribution to journal › Article › Academic › peer-review

TY - JOUR

T1 - LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A

AU - Asgekar, A.

AU - Oonk, J.B.R.

AU - Yatawatta, S.

AU - van Weeren, R.J.

AU - McKean, J.P.

AU - White, G.

AU - Jackson, N.

AU - Anderson, J.

AU - Avruch, I.M.

AU - Batejat, F.

AU - Beck, R.

AU - Bell, M.E.

AU - Bell, M.R.

AU - van Bemmel, I.

AU - Bentum, Marinus Jan

AU - Bernardi, G.

AU - Best, P.

AU - Birzan, L.

AU - Bonafede, A.

AU - Braun, R.

AU - Breitling, F.

AU - van de Brink, R.H.

AU - Broderick, J.

AU - Brouw, W.N.

AU - Brüggen, M.

AU - Butcher, H.R.

AU - van Capellen, W.

AU - Ciardi, B.

AU - Conway, J.E.

AU - de Gasperin, F.

AU - de Geus, E.

AU - de Jong, A.

AU - Vos, M.

AU - Duscha, S.

AU - Eislöffel, J.

AU - Falcke, H.

AU - Fallows, R.A.

AU - Ferrari, C.

AU - Frieswijk, W.

AU - Garrett, M.A.

AU - Griessmeier, J.M.

AU - Grit, T.

AU - Gunst, A.W.

AU - Hassall, T.E.

AU - Heald, G.

AU - Hessels, J.W.T.

AU - Hoeft, M.

AU - Iacobelli, M.

AU - Intema, H.

AU - Juette, E.

AU - Karastergiou, A.

AU - Kohler, J

AU - Kondratiev, V.I.

AU - Kuniyoshi, M.

AU - Kuper, G.

AU - Law, C.

AU - van Leeuwen, J.

AU - Maat, P.

AU - Macario, G.

AU - Mann, G.

AU - Markoff, S.

AU - McKay-Bukowski, D.

AU - Mevius, M.

AU - Miller-Jones, J.C.A

AU - Mol, J.D.

AU - Morganti, R.

AU - Mulcahy, D.D.

AU - Munk, H.

AU - Norden, M.J.

AU - Orrú, E.

AU - Paas, H.

AU - Pandey-Pommier, M.

AU - Pandey, V.N.

AU - Pizzo, R.

AU - Polatidis, A.G.

AU - Reich, W.

AU - Röttgering, H.

AU - Scheers, B.

AU - Schoenmakers, A.

AU - Sluman, J.

AU - Smirnov, O.

AU - Sobey, C.

AU - Steinmetz, M.

AU - Tagger, M.

AU - Tang, Y.

AU - Tasse, C.

AU - Vermeulen, R.

AU - Vocks, C.

AU - Wijers, R.A.M.J.

AU - Wise, M.W.

AU - Wucknitz, O.

AU - Zarka, P.

N1 - eemcs-eprint-24495

PY - 2013/2/28

Y1 - 2013/2/28

N2 - 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 α 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.

AB - 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 α 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.

KW - EWI-24495

KW - IR-89496

KW - METIS-302711

KW - ISM: clouds / radio lines: ISM / ISM: individual objects: Cassiopeia A

U2 - 10.1051/0004-6361/201221001

DO - 10.1051/0004-6361/201221001

M3 - Article

VL - 551

SP - 1

EP - 5

JO - Astronomy & astrophysics

JF - Astronomy & astrophysics

SN - 0004-6361

IS - L11

ER -