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Low Frequency Radio Observations of Galaxy Clusters and Groups pp 97–129Cite as

LOFAR HBA Observations of NGC 6251

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Abstract

In this chapter I present total intensity and polarised intensity observations of the nearby giant radio galaxy NGC 6251 with LOFAR HBA. NGC 6251 is a giant radio galaxy with a borderline FRI/FRII morphology. The main jet and lobe aregma centre brightened like an FRI however there is a hot spot or ‘warm spot’ in the lobe suggestive of an FRII. In contrast the counter jet and lobe are edge brightened with another hot spot in the southern lobe. The radio power at 178 MHz is \(P_\mathrm{178 MHz}\approx 1.4\times 10^{25}\) W Hz\(^{-1}\) (Waggett et al. 1977) which is near the 178 MHz boundary between FRI and FRII, \(P_\mathrm{178MHz}\approx 2\times 10^{25}h_{50}^{-2}\) W Hz\(^{-1}\) or \(P_\mathrm{178MHz}\approx 1\times 10^{25}h_{70}^{-2}\) W Hz\(^{-1}\) (Fanaroff and Riley 1974). The images presented in this chapter are the highest sensitivity and resolution images of NGC 6251 at these frequencies to date. I will also present the first detailed spectral index maps of the source at such low frequencies.

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Notes

  1. 1.

    AOFlagger can be found at https://sourceforge.net/projects/aoflagger.

  2. 2.

    The code used to fit the flux correction was written by Martin Hardcastle and is available from https://github.com/mhardcastle/surveys-pipeline.

  3. 3.

    pybdsf documentation: http://www.astron.nl/citt/pybdsm/.

  4. 4.

    RMExtract code can be found at https://github.com/maaijke/RMextract.

  5. 5.

    pyrmsynth code can be found at https://github.com/mrbell/pyrmsynth.

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  1. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester, UK

    Thérèse Cantwell

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Cantwell, T. (2018). LOFAR HBA Observations of NGC 6251. In: Low Frequency Radio Observations of Galaxy Clusters and Groups. Springer Theses. Springer, Cham. https://doi.org/10.1007/978-3-319-97976-2_5

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