University of Hertfordshire

Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR

Research output: Contribution to journalArticle

Standard

Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR. / O'Sullivan, Shane P.; Brüggen, M.; Eck, C. L. Van; Hardcastle, M. J.; Haverkorn, M.; Shimwell, T. W.; Tasse, C.; Vacca, V.; Horellou, C.; Heald, G.

In: Galaxies, 29.11.2018.

Research output: Contribution to journalArticle

Harvard

O'Sullivan, SP, Brüggen, M, Eck, CLV, Hardcastle, MJ, Haverkorn, M, Shimwell, TW, Tasse, C, Vacca, V, Horellou, C & Heald, G 2018, 'Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR' Galaxies. DOI: 10.3390/galaxies6040126

APA

O'Sullivan, S. P., Brüggen, M., Eck, C. L. V., Hardcastle, M. J., Haverkorn, M., Shimwell, T. W., ... Heald, G. (2018). Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR. Galaxies. DOI: 10.3390/galaxies6040126

Vancouver

O'Sullivan SP, Brüggen M, Eck CLV, Hardcastle MJ, Haverkorn M, Shimwell TW et al. Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR. Galaxies. 2018 Nov 29. Available from, DOI: 10.3390/galaxies6040126

Author

O'Sullivan, Shane P. ; Brüggen, M. ; Eck, C. L. Van ; Hardcastle, M. J. ; Haverkorn, M. ; Shimwell, T. W. ; Tasse, C. ; Vacca, V. ; Horellou, C. ; Heald, G./ Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR. In: Galaxies. 2018

Bibtex

@article{e37c45b10a604706b26966b203bb1858,
title = "Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR",
abstract = "The technique of Faraday tomography is a key tool for the study of magnetised plasmas in the new era of broadband radio polarisation observations. In particular, observations at metre-wavelengths provide significantly better Faraday depth accuracies compared to traditional cm-wavelength observations. However, the effect of Faraday depolarisation makes the polarised signal very challenging to detect at metre wavelengths (MHz frequencies). In this work, Faraday tomography is used to characterise the Faraday rotation properties of polarised sources found in data from the LOFAR Two-Metre Sky Survey (LoTSS). Of the 76 extragalactic polarised sources analysed here, we find that all host a radio-loud AGN. The majority of the sources ($\sim$64{\%}) are large FRII radio galaxies with a median projected linear size of 710 kpc and median radio luminosity at 144 MHz of $4\times10^{26}$ W Hz$^{-1}$ (with $\sim$13{\%} of all sources having a linear size $>1$ Mpc). In several cases, both hotspots are detected in polarisation at an angular resolution of $\sim$20{"}. One such case allowed a study of intergalactic magnetic fields on scales of 3.4 Mpc. Other detected source types include an FRI radio galaxy and at least 8 blazars. Most sources display simple Faraday spectra, however, we highlight one blazar that displays a complex Faraday spectrum, with two close peaks in the Faraday dispersion function.",
keywords = "astro-ph.HE, astro-ph.CO, astro-ph.GA",
author = "O'Sullivan, {Shane P.} and M. Br{\"u}ggen and Eck, {C. L. Van} and Hardcastle, {M. J.} and M. Haverkorn and Shimwell, {T. W.} and C. Tasse and V. Vacca and C. Horellou and G. Heald",
note = "14 pages, 6 figures. Accepted for publication in {"}The Power of Faraday Tomography{"} special issue of Galaxies",
year = "2018",
month = "11",
day = "29",
doi = "10.3390/galaxies6040126",
language = "English",
journal = "Galaxies",
issn = "2075-4434",
publisher = "MDPI",

}

RIS

TY - JOUR

T1 - Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR

AU - O'Sullivan,Shane P.

AU - Brüggen,M.

AU - Eck,C. L. Van

AU - Hardcastle,M. J.

AU - Haverkorn,M.

AU - Shimwell,T. W.

AU - Tasse,C.

AU - Vacca,V.

AU - Horellou,C.

AU - Heald,G.

N1 - 14 pages, 6 figures. Accepted for publication in "The Power of Faraday Tomography" special issue of Galaxies

PY - 2018/11/29

Y1 - 2018/11/29

N2 - The technique of Faraday tomography is a key tool for the study of magnetised plasmas in the new era of broadband radio polarisation observations. In particular, observations at metre-wavelengths provide significantly better Faraday depth accuracies compared to traditional cm-wavelength observations. However, the effect of Faraday depolarisation makes the polarised signal very challenging to detect at metre wavelengths (MHz frequencies). In this work, Faraday tomography is used to characterise the Faraday rotation properties of polarised sources found in data from the LOFAR Two-Metre Sky Survey (LoTSS). Of the 76 extragalactic polarised sources analysed here, we find that all host a radio-loud AGN. The majority of the sources ($\sim$64%) are large FRII radio galaxies with a median projected linear size of 710 kpc and median radio luminosity at 144 MHz of $4\times10^{26}$ W Hz$^{-1}$ (with $\sim$13% of all sources having a linear size $>1$ Mpc). In several cases, both hotspots are detected in polarisation at an angular resolution of $\sim$20". One such case allowed a study of intergalactic magnetic fields on scales of 3.4 Mpc. Other detected source types include an FRI radio galaxy and at least 8 blazars. Most sources display simple Faraday spectra, however, we highlight one blazar that displays a complex Faraday spectrum, with two close peaks in the Faraday dispersion function.

AB - The technique of Faraday tomography is a key tool for the study of magnetised plasmas in the new era of broadband radio polarisation observations. In particular, observations at metre-wavelengths provide significantly better Faraday depth accuracies compared to traditional cm-wavelength observations. However, the effect of Faraday depolarisation makes the polarised signal very challenging to detect at metre wavelengths (MHz frequencies). In this work, Faraday tomography is used to characterise the Faraday rotation properties of polarised sources found in data from the LOFAR Two-Metre Sky Survey (LoTSS). Of the 76 extragalactic polarised sources analysed here, we find that all host a radio-loud AGN. The majority of the sources ($\sim$64%) are large FRII radio galaxies with a median projected linear size of 710 kpc and median radio luminosity at 144 MHz of $4\times10^{26}$ W Hz$^{-1}$ (with $\sim$13% of all sources having a linear size $>1$ Mpc). In several cases, both hotspots are detected in polarisation at an angular resolution of $\sim$20". One such case allowed a study of intergalactic magnetic fields on scales of 3.4 Mpc. Other detected source types include an FRI radio galaxy and at least 8 blazars. Most sources display simple Faraday spectra, however, we highlight one blazar that displays a complex Faraday spectrum, with two close peaks in the Faraday dispersion function.

KW - astro-ph.HE

KW - astro-ph.CO

KW - astro-ph.GA

U2 - 10.3390/galaxies6040126

DO - 10.3390/galaxies6040126

M3 - Article

JO - Galaxies

T2 - Galaxies

JF - Galaxies

SN - 2075-4434

ER -