Wide-field LOFAR imaging of the field around the double-double radio galaxy B1834+620: A fresh view on a restarted AGN and doubeltjes

Orru E, Van Velzen S, Pizzo RF, Yatawatta S, Paladino R, Iacobelli M, Murgia M, Falcke H, Morganti R, De Bruyn AG, Ferrari C, Anderson J, Bonafede A, Mulcahy D, Asgekar A, Avruch IM, Beck R, Bell ME, Van Bemmel I, Bentum MJ, Bernardi G, Best P, Breitling F, Broderick JW, Bruggen M, Butcher HR, Ciardi B, Conway JE, Corstanje A, De Geus E, Deller A, Duscha S, Eisloffel J, Engels D, Frieswijk W, Garrett MA, Grießmeier J, Gunst AW, Hamaker JP, Heald G, Hoeft M, Van Der Horst AJ, Intema H, Juette E, Kohler J, Kondratiev VI, Kuniyoshi M, Kuper G, Loose M, Maat P, Mann G, Markoff S, McFadden R, McKay-BGBRowski D, Miley G, Moldon J, Molenaar G, Munk H, Nelles A, Paas H, Pandey-Pommier M, Pandey VN, Pietka G, Polatidis AG, Reich W, Rottgering H, Rowlinson A, Scaife A, Schoenmakers A, Schwarz D, Serylak M, Shulevski A, Smirnov O, Steinmetz M, Stewart A, Swinbank J, Tagger M, Tasse C, Thoudam S, Toribio MC, Vermeulen R, Vocks C, Van Weeren RJ, Wijers RA, Wise MW, Wucknitz O (2015)

Publication Type: Journal article

Publication year: 2015

Journal

Book Volume: 584

Article Number: A112

DOI: 10.1051/0004-6361/201526501

Abstract

The existence of double-double radio galaxies (DDRGs) is evidence for recurrent jet activity in active galactic nuclei (AGN), as expected from standard accretion models. A detailed study of these rare sources provides new perspectives for investigating the AGN duty cycle, AGN-galaxy feedback, and accretion mechanisms. Large catalogues of radio sources, on the other hand, provide statistical information about the evolution of the radio-loud AGN population out to high redshifts. Aims. Using wide-field imaging with the LOFAR telescope, we study both a well-known DDRG as well as a large number of radio sources in the field of view. Methods. We present a high resolution image of the DDRG B1834+620 obtained at 144 MHz using LOFAR commissioning data. Our image covers about 100 square degrees and contains over 1000 sources. Results. The four components of the DDRG B1834+620 have been resolved for the first time at 144 MHz. Inner lobes were found to point towards the direction of the outer lobes, unlike standard FR II sources. Polarized emission was detected at +60 rad m^-2 in the northern outer lobe. The high spatial resolution allows the identification of a large number of small double-lobed radio sources; roughly 10% of all sources in the field are doubles with a separation smaller than 1′. Conclusions. The spectral fit of the four components is consistent with a scenario in which the outer lobes are still active or the jets recently switched off, while emission of the inner lobes is the result of a mix-up of new and old jet activity. From the presence of the newly extended features in the inner lobes of the DDRG, we can infer that the mechanism responsible for their formation is the bow shock that is driven by the newly launched jet. We find that the density of the small doubles exceeds the density of FR II sources with similar properties at 1.4 GHz, but this difference becomes smaller for low flux densities. Finally, we show that the significant challenges of wide-field imaging (e.g., time and frequency variation of the beam, directional dependent calibration errors) can be solved using LOFAR commissioning data, thus demonstrating the potential of the full LOFAR telescope to discover millions of powerful AGN at redshift z ∼ 1.

Authors with CRIS profile

Involved external institutions

Astron Netherlands (NL) University of Bologna / Università di Bologna Italy (IT) Lagrange Laboratory France (FR) Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ Germany (DE) Universität Hamburg (UHH) Germany (DE) University of Manchester United Kingdom (GB) Kapteyn Astronomical Institute Netherlands (NL) Australia Telescope National Facility (ATNF) Australia (AU) Australian National University (ANU) Australia (AU) Thüringer Landessternwarte Tautenburg (TLS) - Karl-Schwarzschild-Observatorium Germany (DE) University of Orléans / Université d'Orléans France (FR) Radboud University Nijmegen Netherlands (NL) Max-Planck-Institut für Radioastronomie / Max Planck Institute for Radio Astronomy Germany (DE) INAF-Osservatorio Astronomico di Cagliari Italy (IT) Smithsonian Institution United States (USA) (US) Leibniz Institute for Astrophysics Potsdam / Leibniz-Institut für Astrophysik Potsdam Germany (DE) Onsala Space Observatory (OSO) Sweden (SE) Leiden University Netherlands (NL) Sodankylä Geophysical Observatory Finland (FI) University of Southampton United Kingdom (GB) Max-Planck-Institut für Astrophysik / Max Planck Institute for Astrophysics Germany (DE) University of Amsterdam Netherlands (NL) University of Groningen / Rijksuniversiteit Groningen Netherlands (NL) Centre de Recherche Astrophysique de Lyon (CRAL) France (FR) University of Edinburgh United Kingdom (GB) George Washington University (GWU) United States (USA) (US) Ruhr-Universität Bochum (RUB) Germany (DE) National Astronomical Observatory of Japan / 国立天文台(NAOJ) Japan (JP) University of Oxford United Kingdom (GB) Rhodes University South Africa (ZA) Universität Bielefeld Germany (DE) Paris Observatory / Observatoire de Paris France (FR)

How to cite

APA:

Orru, E., Van Velzen, S., Pizzo, R.F., Yatawatta, S., Paladino, R., Iacobelli, M.,... Wucknitz, O. (2015). Wide-field LOFAR imaging of the field around the double-double radio galaxy B1834+620: A fresh view on a restarted AGN and doubeltjes. Astronomy & Astrophysics, 584. https://dx.doi.org/10.1051/0004-6361/201526501

MLA:

Orru, E., et al. "Wide-field LOFAR imaging of the field around the double-double radio galaxy B1834+620: A fresh view on a restarted AGN and doubeltjes." Astronomy & Astrophysics 584 (2015).

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