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LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra

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LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra. / McKean, J. P.; Godfrey, L. E H; Vegetti, S.; Wise, Michael W.; Morganti, R.; Hardcastle, M. J.; Rafferty, D.; Avruch, I. M.; Beck, R.; Bell, M. E.; Bemmel, I. M. van; Bentum, M. J.; Bernardi, G.; Best, Philip; Blaauw, R.; Bonafede, A.; Breitling, F.; Broderick, J. W.; Brüggen, Marcus; Cerrigone, L.; Ciardi, B.; De Gasperin, Francesco; Deller, A.; Duscha, S.; Engels, D.; Falcke, H.; Fallows, R. A.; Frieswijk, W.; Garrett, M.A.; Grießmeier, J. -M.; Haarlem, M. P. van; Heald, G.; Hoeft, Matthias; van der, HorstA J.; Iacobelli, M.; Interna, H.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Koopmans, L. V E; Kuniyoshi, M.; Kuper, G.; Van Leeuwen, J.; Maat, P.; Mann, R. G.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; Mulcahy, D. D.; Munk, H.; Nelles, A.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pietka, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Rottgering, H. J. A.; Rowlinson, A.; Scaife, A. M M; Serylak, M.; Shulevski, Alexander; Sluman, J.; Smirnov, O.; Steinmetz, M.; Stewart, A. J.; Swinbank, J.; Tagger, M.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; Vocks, C.; Van Weeren, R. J.; Wucknitz, O.; Yatawatta, S.; Zarka, P.

In: Monthly Notices of the Royal Astronomical Society, Vol. 463, No. 3, 01.12.2016, p. 3143-3150.

Research output: Contribution to journalArticlepeer-review

Harvard

McKean, JP, Godfrey, LEH, Vegetti, S, Wise, MW, Morganti, R, Hardcastle, MJ, Rafferty, D, Avruch, IM, Beck, R, Bell, ME, Bemmel, IMV, Bentum, MJ, Bernardi, G, Best, P, Blaauw, R, Bonafede, A, Breitling, F, Broderick, JW, Brüggen, M, Cerrigone, L, Ciardi, B, De Gasperin, F, Deller, A, Duscha, S, Engels, D, Falcke, H, Fallows, RA, Frieswijk, W, Garrett, MA, Grießmeier, J-M, Haarlem, MPV, Heald, G, Hoeft, M, van der, HJ, Iacobelli, M, Interna, H, Juette, E, Karastergiou, A, Kondratiev, VI, Koopmans, LVE, Kuniyoshi, M, Kuper, G, Van Leeuwen, J, Maat, P, Mann, RG, Markoff, S, McFadden, R, McKay-Bukowski, D, Mulcahy, DD, Munk, H, Nelles, A, Orru, E, Paas, H, Pandey-Pommier, M, Pietka, M, Pizzo, R, Polatidis, AG, Reich, W, Rottgering, HJA, Rowlinson, A, Scaife, AMM, Serylak, M, Shulevski, A, Sluman, J, Smirnov, O, Steinmetz, M, Stewart, AJ, Swinbank, J, Tagger, M, Thoudam, S, Toribio, MC, Vermeulen, R, Vocks, C, Van Weeren, RJ, Wucknitz, O, Yatawatta, S & Zarka, P 2016, 'LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra', Monthly Notices of the Royal Astronomical Society, vol. 463, no. 3, pp. 3143-3150. https://doi.org/10.1093/mnras/stw2105

APA

McKean, J. P., Godfrey, L. E. H., Vegetti, S., Wise, M. W., Morganti, R., Hardcastle, M. J., Rafferty, D., Avruch, I. M., Beck, R., Bell, M. E., Bemmel, I. M. V., Bentum, M. J., Bernardi, G., Best, P., Blaauw, R., Bonafede, A., Breitling, F., Broderick, J. W., Brüggen, M., ... Zarka, P. (2016). LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra. Monthly Notices of the Royal Astronomical Society, 463(3), 3143-3150. https://doi.org/10.1093/mnras/stw2105

Vancouver

Author

McKean, J. P. ; Godfrey, L. E H ; Vegetti, S. ; Wise, Michael W. ; Morganti, R. ; Hardcastle, M. J. ; Rafferty, D. ; Avruch, I. M. ; Beck, R. ; Bell, M. E. ; Bemmel, I. M. van ; Bentum, M. J. ; Bernardi, G. ; Best, Philip ; Blaauw, R. ; Bonafede, A. ; Breitling, F. ; Broderick, J. W. ; Brüggen, Marcus ; Cerrigone, L. ; Ciardi, B. ; De Gasperin, Francesco ; Deller, A. ; Duscha, S. ; Engels, D. ; Falcke, H. ; Fallows, R. A. ; Frieswijk, W. ; Garrett, M.A. ; Grießmeier, J. -M. ; Haarlem, M. P. van ; Heald, G. ; Hoeft, Matthias ; van der, HorstA J. ; Iacobelli, M. ; Interna, H. ; Juette, E. ; Karastergiou, A. ; Kondratiev, V. I. ; Koopmans, L. V E ; Kuniyoshi, M. ; Kuper, G. ; Van Leeuwen, J. ; Maat, P. ; Mann, R. G. ; Markoff, S. ; McFadden, R. ; McKay-Bukowski, D. ; Mulcahy, D. D. ; Munk, H. ; Nelles, A. ; Orru, E. ; Paas, H. ; Pandey-Pommier, M. ; Pietka, M. ; Pizzo, R. ; Polatidis, A. G. ; Reich, W. ; Rottgering, H. J. A. ; Rowlinson, A. ; Scaife, A. M M ; Serylak, M. ; Shulevski, Alexander ; Sluman, J. ; Smirnov, O. ; Steinmetz, M. ; Stewart, A. J. ; Swinbank, J. ; Tagger, M. ; Thoudam, S. ; Toribio, M. C. ; Vermeulen, R. ; Vocks, C. ; Van Weeren, R. J. ; Wucknitz, O. ; Yatawatta, S. ; Zarka, P. / LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra. In: Monthly Notices of the Royal Astronomical Society. 2016 ; Vol. 463, No. 3. pp. 3143-3150.

Bibtex

@article{b634f567ef9d48548d6dd133e0b2cbdf,
title = "LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra",
abstract = "The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termination. These processes are responsible for the dissipation of jet kinetic energy, particle acceleration, and magnetic-field generation. Here, we report new observations of the powerful radio galaxy Cygnus A using the Low Frequency Array (LOFAR) between 109 and 183 MHz, at an angular resolution of ~3.5 arcsec. The radio emission of the lobes is found to have a complex spectral index distribution, with a spectral steepening found towards the centre of the source. For the first time, a turnover in the radio spectrum of the two main hotspots of Cygnus A has been directly observed. By combining our LOFAR imaging with data from the Very Large Array at higher frequencies, we show that the very rapid turnover in the hotspot spectra cannot be explained by a low-energy cut-off in the electron energy distribution, as has been previously suggested. Thermal (free-free) absorption or synchrotron self-absorption models are able to describe the low-frequency spectral shape of the hotspots; however, as with previous studies, we find that the implied model parameters are unlikely, and interpreting the spectra of the hotspots remains problematic.",
keywords = "Radio continuum: galaxies",
author = "McKean, {J. P.} and Godfrey, {L. E H} and S. Vegetti and Wise, {Michael W.} and R. Morganti and Hardcastle, {M. J.} and D. Rafferty and Avruch, {I. M.} and R. Beck and Bell, {M. E.} and Bemmel, {I. M. van} and Bentum, {M. J.} and G. Bernardi and Philip Best and R. Blaauw and A. Bonafede and F. Breitling and Broderick, {J. W.} and Marcus Br{\"u}ggen and L. Cerrigone and B. Ciardi and {De Gasperin}, Francesco and A. Deller and S. Duscha and D. Engels and H. Falcke and Fallows, {R. A.} and W. Frieswijk and M.A. Garrett and Grie{\ss}meier, {J. -M.} and Haarlem, {M. P. van} and G. Heald and Matthias Hoeft and {van der}, {HorstA J.} and M. Iacobelli and H. Interna and E. Juette and A. Karastergiou and Kondratiev, {V. I.} and Koopmans, {L. V E} and M. Kuniyoshi and G. Kuper and {Van Leeuwen}, J. and P. Maat and Mann, {R. G.} and S. Markoff and R. McFadden and D. McKay-Bukowski and Mulcahy, {D. D.} and H. Munk and A. Nelles and E. Orru and H. Paas and M. Pandey-Pommier and M. Pietka and R. Pizzo and Polatidis, {A. G.} and W. Reich and Rottgering, {H. J. A.} and A. Rowlinson and Scaife, {A. M M} and M. Serylak and Alexander Shulevski and J. Sluman and O. Smirnov and M. Steinmetz and Stewart, {A. J.} and J. Swinbank and M. Tagger and S. Thoudam and Toribio, {M. C.} and R. Vermeulen and C. Vocks and {Van Weeren}, {R. J.} and O. Wucknitz and S. Yatawatta and P. Zarka",
note = "This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. {\textcopyright} 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.",
year = "2016",
month = dec,
day = "1",
doi = "10.1093/mnras/stw2105",
language = "English",
volume = "463",
pages = "3143--3150",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "3",

}

RIS

TY - JOUR

T1 - LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra

AU - McKean, J. P.

AU - Godfrey, L. E H

AU - Vegetti, S.

AU - Wise, Michael W.

AU - Morganti, R.

AU - Hardcastle, M. J.

AU - Rafferty, D.

AU - Avruch, I. M.

AU - Beck, R.

AU - Bell, M. E.

AU - Bemmel, I. M. van

AU - Bentum, M. J.

AU - Bernardi, G.

AU - Best, Philip

AU - Blaauw, R.

AU - Bonafede, A.

AU - Breitling, F.

AU - Broderick, J. W.

AU - Brüggen, Marcus

AU - Cerrigone, L.

AU - Ciardi, B.

AU - De Gasperin, Francesco

AU - Deller, A.

AU - Duscha, S.

AU - Engels, D.

AU - Falcke, H.

AU - Fallows, R. A.

AU - Frieswijk, W.

AU - Garrett, M.A.

AU - Grießmeier, J. -M.

AU - Haarlem, M. P. van

AU - Heald, G.

AU - Hoeft, Matthias

AU - van der, HorstA J.

AU - Iacobelli, M.

AU - Interna, H.

AU - Juette, E.

AU - Karastergiou, A.

AU - Kondratiev, V. I.

AU - Koopmans, L. V E

AU - Kuniyoshi, M.

AU - Kuper, G.

AU - Van Leeuwen, J.

AU - Maat, P.

AU - Mann, R. G.

AU - Markoff, S.

AU - McFadden, R.

AU - McKay-Bukowski, D.

AU - Mulcahy, D. D.

AU - Munk, H.

AU - Nelles, A.

AU - Orru, E.

AU - Paas, H.

AU - Pandey-Pommier, M.

AU - Pietka, M.

AU - Pizzo, R.

AU - Polatidis, A. G.

AU - Reich, W.

AU - Rottgering, H. J. A.

AU - Rowlinson, A.

AU - Scaife, A. M M

AU - Serylak, M.

AU - Shulevski, Alexander

AU - Sluman, J.

AU - Smirnov, O.

AU - Steinmetz, M.

AU - Stewart, A. J.

AU - Swinbank, J.

AU - Tagger, M.

AU - Thoudam, S.

AU - Toribio, M. C.

AU - Vermeulen, R.

AU - Vocks, C.

AU - Van Weeren, R. J.

AU - Wucknitz, O.

AU - Yatawatta, S.

AU - Zarka, P.

N1 - This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

PY - 2016/12/1

Y1 - 2016/12/1

N2 - The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termination. These processes are responsible for the dissipation of jet kinetic energy, particle acceleration, and magnetic-field generation. Here, we report new observations of the powerful radio galaxy Cygnus A using the Low Frequency Array (LOFAR) between 109 and 183 MHz, at an angular resolution of ~3.5 arcsec. The radio emission of the lobes is found to have a complex spectral index distribution, with a spectral steepening found towards the centre of the source. For the first time, a turnover in the radio spectrum of the two main hotspots of Cygnus A has been directly observed. By combining our LOFAR imaging with data from the Very Large Array at higher frequencies, we show that the very rapid turnover in the hotspot spectra cannot be explained by a low-energy cut-off in the electron energy distribution, as has been previously suggested. Thermal (free-free) absorption or synchrotron self-absorption models are able to describe the low-frequency spectral shape of the hotspots; however, as with previous studies, we find that the implied model parameters are unlikely, and interpreting the spectra of the hotspots remains problematic.

AB - The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termination. These processes are responsible for the dissipation of jet kinetic energy, particle acceleration, and magnetic-field generation. Here, we report new observations of the powerful radio galaxy Cygnus A using the Low Frequency Array (LOFAR) between 109 and 183 MHz, at an angular resolution of ~3.5 arcsec. The radio emission of the lobes is found to have a complex spectral index distribution, with a spectral steepening found towards the centre of the source. For the first time, a turnover in the radio spectrum of the two main hotspots of Cygnus A has been directly observed. By combining our LOFAR imaging with data from the Very Large Array at higher frequencies, we show that the very rapid turnover in the hotspot spectra cannot be explained by a low-energy cut-off in the electron energy distribution, as has been previously suggested. Thermal (free-free) absorption or synchrotron self-absorption models are able to describe the low-frequency spectral shape of the hotspots; however, as with previous studies, we find that the implied model parameters are unlikely, and interpreting the spectra of the hotspots remains problematic.

KW - Radio continuum: galaxies

UR - http://www.scopus.com/inward/record.url?scp=85014758165&partnerID=8YFLogxK

U2 - 10.1093/mnras/stw2105

DO - 10.1093/mnras/stw2105

M3 - Article

AN - SCOPUS:85014758165

VL - 463

SP - 3143

EP - 3150

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -