Modelling of the Spectral Energy Distribution of Fornax A: Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes

B. McKinley; R. Yang; M. López-Caniego; F. Briggs; N. Hurley-Walker; R. B. Wayth; A. R. Offringa; R. Crocker; G. Bernardi; P. Procopio; B. M. Gaensler; S. J. Tingay; M. Johnston-Hollitt; M. McDonald; M. Bell; N. D. R. Bhat; J. D. Bowman; R. J. Cappallo; B. E. Corey; A. A. Deshpande; D. Emrich; A. Ewall-Wice; L. Feng; R. Goeke; L. J. Greenhill; B. J. Hazelton; J. N. Hewitt; L. Hindson; D. Jacobs; D. L. Kaplan; J. C. Kasper; E. Kratzenberg; N. Kudryavtseva; E. Lenc; C. J. Lonsdale; M. J. Lynch; S. R. McWhirter; D. A. Mitchell; M. F. Morales; E. Morgan; D. Oberoi; S. M. Ord; B. Pindor; T. Prabu; J. Riding; A. E. E. Rogers; D. A. Roshi; N. Udaya Shankar; K. S. Srivani; R. Subrahmanyan; M. Waterson; R. L. Webster; A. R. Whitney; A. Williams; C. L. Williams

doi:10.1093/mnras/stu2310

Modelling of the Spectral Energy Distribution of Fornax A: Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes

B. McKinley, R. Yang, M. López-Caniego, F. Briggs, N. Hurley-Walker, R. B. Wayth, A. R. Offringa, R. Crocker, G. Bernardi, P. Procopio, B. M. Gaensler, S. J. Tingay, M. Johnston-Hollitt, M. McDonald, M. Bell, N. D. R. Bhat, J. D. Bowman, R. J. Cappallo, B. E. Corey, A. A. DeshpandeD. Emrich, A. Ewall-Wice, L. Feng, R. Goeke, L. J. Greenhill, B. J. Hazelton, J. N. Hewitt, L. Hindson, D. Jacobs, D. L. Kaplan, J. C. Kasper, E. Kratzenberg, N. Kudryavtseva, E. Lenc, C. J. Lonsdale, M. J. Lynch, S. R. McWhirter, D. A. Mitchell, M. F. Morales, E. Morgan, D. Oberoi, S. M. Ord, B. Pindor, T. Prabu, J. Riding, A. E. E. Rogers, D. A. Roshi, N. Udaya Shankar, K. S. Srivani, R. Subrahmanyan, M. Waterson, R. L. Webster, A. R. Whitney, A. Williams, C. L. Williams

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Abstract

We present new low-frequency observations of the nearby radio galaxy Fornax A at 154 MHz with the Murchison Widefield Array, microwave flux-density measurements obtained from WMAP and Planck data, and gamma-ray flux densities obtained from Fermi data. We also compile a comprehensive list of previously published images and flux-density measurements at radio, microwave and X-ray energies. A detailed analysis of the spectrum of Fornax A between 154 MHz and 1510 MHz reveals that both radio lobes have a similar spatially-averaged spectral index, and that there exists a steep-spectrum bridge of diffuse emission between the lobes. Taking the spectral index of both lobes to be the same, we model the spectral energy distribution of Fornax A across an energy range spanning eighteen orders of magnitude, to investigate the origin of the X-ray and gamma-ray emission. A standard leptonic model for the production of both the X-rays and gamma-rays by inverse-Compton scattering does not fit the multi-wavelength observations. Our results best support a scenario where the X-rays are produced by inverse-Compton scattering and the gamma-rays are produced primarily by hadronic processes confined to the filamentary structures of the Fornax A lobes.

Original language	English
Pages (from-to)	3478-3491
Journal	Monthly Notices of the Royal Astronomical Society (MNRAS)
Volume	447
Issue number	4
Early online date	8 Dec 2014
DOIs	https://doi.org/10.1093/mnras/stu2310
Publication status	Published - 1 Feb 2015

Keywords

astro-ph.HE

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10.1093/mnras/stu2310

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McKinley, B., Yang, R., López-Caniego, M., Briggs, F., Hurley-Walker, N., Wayth, R. B., Offringa, A. R., Crocker, R., Bernardi, G., Procopio, P., Gaensler, B. M., Tingay, S. J., Johnston-Hollitt, M., McDonald, M., Bell, M., Bhat, N. D. R., Bowman, J. D., Cappallo, R. J., Corey, B. E., ... Williams, C. L. (2015). Modelling of the Spectral Energy Distribution of Fornax A: Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes. Monthly Notices of the Royal Astronomical Society (MNRAS), 447(4), 3478-3491. https://doi.org/10.1093/mnras/stu2310

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title = "Modelling of the Spectral Energy Distribution of Fornax A: Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes",

abstract = "We present new low-frequency observations of the nearby radio galaxy Fornax A at 154 MHz with the Murchison Widefield Array, microwave flux-density measurements obtained from WMAP and Planck data, and gamma-ray flux densities obtained from Fermi data. We also compile a comprehensive list of previously published images and flux-density measurements at radio, microwave and X-ray energies. A detailed analysis of the spectrum of Fornax A between 154 MHz and 1510 MHz reveals that both radio lobes have a similar spatially-averaged spectral index, and that there exists a steep-spectrum bridge of diffuse emission between the lobes. Taking the spectral index of both lobes to be the same, we model the spectral energy distribution of Fornax A across an energy range spanning eighteen orders of magnitude, to investigate the origin of the X-ray and gamma-ray emission. A standard leptonic model for the production of both the X-rays and gamma-rays by inverse-Compton scattering does not fit the multi-wavelength observations. Our results best support a scenario where the X-rays are produced by inverse-Compton scattering and the gamma-rays are produced primarily by hadronic processes confined to the filamentary structures of the Fornax A lobes.",

keywords = "astro-ph.HE",

author = "B. McKinley and R. Yang and M. L{\'o}pez-Caniego and F. Briggs and N. Hurley-Walker and Wayth, {R. B.} and Offringa, {A. R.} and R. Crocker and G. Bernardi and P. Procopio and Gaensler, {B. M.} and Tingay, {S. J.} and M. Johnston-Hollitt and M. McDonald and M. Bell and Bhat, {N. D. R.} and Bowman, {J. D.} and Cappallo, {R. J.} and Corey, {B. E.} and Deshpande, {A. A.} and D. Emrich and A. Ewall-Wice and L. Feng and R. Goeke and Greenhill, {L. J.} and Hazelton, {B. J.} and Hewitt, {J. N.} and L. Hindson and D. Jacobs and Kaplan, {D. L.} and Kasper, {J. C.} and E. Kratzenberg and N. Kudryavtseva and E. Lenc and Lonsdale, {C. J.} and Lynch, {M. J.} and McWhirter, {S. R.} and Mitchell, {D. A.} and Morales, {M. F.} and E. Morgan and D. Oberoi and Ord, {S. M.} and B. Pindor and T. Prabu and J. Riding and Rogers, {A. E. E.} and Roshi, {D. A.} and Shankar, {N. Udaya} and Srivani, {K. S.} and R. Subrahmanyan and M. Waterson and Webster, {R. L.} and Whitney, {A. R.} and A. Williams and Williams, {C. L.}",

note = "This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. {\textcopyright} 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.",

year = "2015",

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day = "1",

doi = "10.1093/mnras/stu2310",

language = "English",

volume = "447",

pages = "3478--3491",

journal = "Monthly Notices of the Royal Astronomical Society (MNRAS)",

issn = "0035-8711",

publisher = "Oxford University Press (OUP)",

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McKinley, B, Yang, R, López-Caniego, M, Briggs, F, Hurley-Walker, N, Wayth, RB, Offringa, AR, Crocker, R, Bernardi, G, Procopio, P, Gaensler, BM, Tingay, SJ, Johnston-Hollitt, M, McDonald, M, Bell, M, Bhat, NDR, Bowman, JD, Cappallo, RJ, Corey, BE, Deshpande, AA, Emrich, D, Ewall-Wice, A, Feng, L, Goeke, R, Greenhill, LJ, Hazelton, BJ, Hewitt, JN, Hindson, L, Jacobs, D, Kaplan, DL, Kasper, JC, Kratzenberg, E, Kudryavtseva, N, Lenc, E, Lonsdale, CJ, Lynch, MJ, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, Oberoi, D, Ord, SM, Pindor, B, Prabu, T, Riding, J, Rogers, AEE, Roshi, DA, Shankar, NU, Srivani, KS, Subrahmanyan, R, Waterson, M, Webster, RL, Whitney, AR, Williams, A & Williams, CL 2015, 'Modelling of the Spectral Energy Distribution of Fornax A: Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes', Monthly Notices of the Royal Astronomical Society (MNRAS), vol. 447, no. 4, pp. 3478-3491. https://doi.org/10.1093/mnras/stu2310

TY - JOUR

T1 - Modelling of the Spectral Energy Distribution of Fornax A

T2 - Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes

AU - McKinley, B.

AU - Yang, R.

AU - López-Caniego, M.

AU - Briggs, F.

AU - Hurley-Walker, N.

AU - Wayth, R. B.

AU - Offringa, A. R.

AU - Crocker, R.

AU - Bernardi, G.

AU - Procopio, P.

AU - Gaensler, B. M.

AU - Tingay, S. J.

AU - Johnston-Hollitt, M.

AU - McDonald, M.

AU - Bell, M.

AU - Bhat, N. D. R.

AU - Bowman, J. D.

AU - Cappallo, R. J.

AU - Corey, B. E.

AU - Deshpande, A. A.

AU - Emrich, D.

AU - Ewall-Wice, A.

AU - Feng, L.

AU - Goeke, R.

AU - Greenhill, L. J.

AU - Hazelton, B. J.

AU - Hewitt, J. N.

AU - Hindson, L.

AU - Jacobs, D.

AU - Kaplan, D. L.

AU - Kasper, J. C.

AU - Kratzenberg, E.

AU - Kudryavtseva, N.

AU - Lenc, E.

AU - Lonsdale, C. J.

AU - Lynch, M. J.

AU - McWhirter, S. R.

AU - Mitchell, D. A.

AU - Morales, M. F.

AU - Morgan, E.

AU - Oberoi, D.

AU - Ord, S. M.

AU - Pindor, B.

AU - Prabu, T.

AU - Riding, J.

AU - Rogers, A. E. E.

AU - Roshi, D. A.

AU - Shankar, N. Udaya

AU - Srivani, K. S.

AU - Subrahmanyan, R.

AU - Waterson, M.

AU - Webster, R. L.

AU - Whitney, A. R.

AU - Williams, A.

AU - Williams, C. L.

N1 - This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

PY - 2015/2/1

Y1 - 2015/2/1

N2 - We present new low-frequency observations of the nearby radio galaxy Fornax A at 154 MHz with the Murchison Widefield Array, microwave flux-density measurements obtained from WMAP and Planck data, and gamma-ray flux densities obtained from Fermi data. We also compile a comprehensive list of previously published images and flux-density measurements at radio, microwave and X-ray energies. A detailed analysis of the spectrum of Fornax A between 154 MHz and 1510 MHz reveals that both radio lobes have a similar spatially-averaged spectral index, and that there exists a steep-spectrum bridge of diffuse emission between the lobes. Taking the spectral index of both lobes to be the same, we model the spectral energy distribution of Fornax A across an energy range spanning eighteen orders of magnitude, to investigate the origin of the X-ray and gamma-ray emission. A standard leptonic model for the production of both the X-rays and gamma-rays by inverse-Compton scattering does not fit the multi-wavelength observations. Our results best support a scenario where the X-rays are produced by inverse-Compton scattering and the gamma-rays are produced primarily by hadronic processes confined to the filamentary structures of the Fornax A lobes.

AB - We present new low-frequency observations of the nearby radio galaxy Fornax A at 154 MHz with the Murchison Widefield Array, microwave flux-density measurements obtained from WMAP and Planck data, and gamma-ray flux densities obtained from Fermi data. We also compile a comprehensive list of previously published images and flux-density measurements at radio, microwave and X-ray energies. A detailed analysis of the spectrum of Fornax A between 154 MHz and 1510 MHz reveals that both radio lobes have a similar spatially-averaged spectral index, and that there exists a steep-spectrum bridge of diffuse emission between the lobes. Taking the spectral index of both lobes to be the same, we model the spectral energy distribution of Fornax A across an energy range spanning eighteen orders of magnitude, to investigate the origin of the X-ray and gamma-ray emission. A standard leptonic model for the production of both the X-rays and gamma-rays by inverse-Compton scattering does not fit the multi-wavelength observations. Our results best support a scenario where the X-rays are produced by inverse-Compton scattering and the gamma-rays are produced primarily by hadronic processes confined to the filamentary structures of the Fornax A lobes.

KW - astro-ph.HE

U2 - 10.1093/mnras/stu2310

DO - 10.1093/mnras/stu2310

M3 - Article

SN - 0035-8711

VL - 447

SP - 3478

EP - 3491

JO - Monthly Notices of the Royal Astronomical Society (MNRAS)

JF - Monthly Notices of the Royal Astronomical Society (MNRAS)

IS - 4

ER -

Modelling of the Spectral Energy Distribution of Fornax A: Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes

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