Wide-field LOFAR imaging of the field around the double-double radio galaxy B1834+620 A fresh view on a restarted AGN and doubeltjes
Journal article, 2015
Context. 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 144MHz 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 similar to 1.
instrumentation: interferometers
galaxies: active
techniques: interferometric
radiation
Author
E. Orru
Radboud University
Netherlands Institute for Radio Astronomy (ASTRON)
S. van Velzen
Johns Hopkins University
Radboud University
R. F. Pizzo
Netherlands Institute for Radio Astronomy (ASTRON)
S. Yatawatta
Netherlands Institute for Radio Astronomy (ASTRON)
Kapteyn Astronomical Institute
R. Paladino
University of Bologna
Istituto nazionale di astrofisica (INAF)
M. Iacobelli
Netherlands Institute for Radio Astronomy (ASTRON)
M. Murgia
Istituto nazionale di astrofisica (INAF)
H. Falcke
Radboud University
Max Planck Society
Netherlands Institute for Radio Astronomy (ASTRON)
R. Morganti
Netherlands Institute for Radio Astronomy (ASTRON)
Kapteyn Astronomical Institute
A. G. de Bruyn
Netherlands Institute for Radio Astronomy (ASTRON)
Kapteyn Astronomical Institute
C. Ferrari
Université Nice Sophia Antipolis (UNS)
J. Anderson
German Research Centre for Geosciences (GFZ)
A. Bonafede
University of Hamburg
D. Mulcahy
University of Manchester
A. Asgekar
Netherlands Institute for Radio Astronomy (ASTRON)
Shell Technology Center
I. M. Avruch
Netherlands Institute for Space Research (SRON)
Kapteyn Astronomical Institute
R. Beck
Max Planck Society
M. E. Bell
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
I. van Bemmel
Joint Institute for VLBI in Europe (JIVE)
Netherlands Institute for Radio Astronomy (ASTRON)
M. J. Bentum
Netherlands Institute for Radio Astronomy (ASTRON)
University of Twente
G. Bernardi
Harvard-Smithsonian Center for Astrophysics
P. Best
University of Edinburgh
F. Breitling
Leibniz Association
J. W. Broderick
University of Southampton
M. Brüggen
University of Hamburg
H. R. Butcher
Australian National University
B. Ciardi
Max Planck Society
John Conway
Chalmers, Earth and Space Sciences, Onsala Space Observatory
A. Corstanje
Radboud University
E. de Geus
Netherlands Institute for Radio Astronomy (ASTRON)
SmarterVision BV
A. Deller
Netherlands Institute for Radio Astronomy (ASTRON)
S. Duscha
Netherlands Institute for Radio Astronomy (ASTRON)
J. Eisloffel
Thüringer Landessternwarte Tautenburg
D. Engels
Hamburg Observatory
W. Frieswijk
Netherlands Institute for Radio Astronomy (ASTRON)
M. A. Garrett
Netherlands Institute for Radio Astronomy (ASTRON)
Leiden University
J. Griessmeier
University of Orléans
A. W. Gunst
Netherlands Institute for Radio Astronomy (ASTRON)
J. P. Hamaker
Netherlands Institute for Radio Astronomy (ASTRON)
G. Heald
Netherlands Institute for Radio Astronomy (ASTRON)
M. Hoeft
Thüringer Landessternwarte Tautenburg
A. J. van der Horst
George Washington University
H. Intema
National Radio Astronomy Observatory
Leiden University
E. Juette
Ruhr-Universität Bochum
J. Kohler
Max Planck Society
V. I. Kondratiev
Astro Space Center of Lebedev Physical Institute
Radboud University
M. Kuniyoshi
National Astronomical Observatory of Japan
G. Kuper
Netherlands Institute for Radio Astronomy (ASTRON)
M. Loose
Netherlands Institute for Radio Astronomy (ASTRON)
P. Maat
Netherlands Institute for Radio Astronomy (ASTRON)
G. Mann
Leibniz Association
S. Markoff
University of Amsterdam
R. McFadden
Netherlands Institute for Radio Astronomy (ASTRON)
D. McKay-Bukowski
University of Oulu
STFC Rutherford Appleton Laboratory
G. Miley
Leiden University
J. Moldon
Netherlands Institute for Radio Astronomy (ASTRON)
G. Molenaar
University of Amsterdam
H. Munk
Netherlands Institute for Radio Astronomy (ASTRON)
A. Nelles
Radboud University
H. Paas
University of Groningen
M. Pandey-Pommier
Lyon Observatory
V. N. Pandey
Netherlands Institute for Radio Astronomy (ASTRON)
G. Pietka
University of Oxford
A. G. Polatidis
Netherlands Institute for Radio Astronomy (ASTRON)
W. Reich
Max Planck Society
H. Rottgering
Leiden University
A. Rowlinson
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
A. Scaife
University of Manchester
A. Schoenmakers
Netherlands Institute for Radio Astronomy (ASTRON)
D. Schwarz
Bielefeld University
M. Serylak
University of Oxford
A. Shulevski
Netherlands Institute for Radio Astronomy (ASTRON)
Kapteyn Astronomical Institute
O. Smirnov
Square Kilometre Array, South Africa
Rhodes University
M. Steinmetz
Leibniz Association
A. Stewart
University of Oxford
J. Swinbank
University of Amsterdam
M. Tagger
University of Orléans
C. Tasse
Observatoire de Paris-Meudon
S. Thoudam
Radboud University
M. C. Toribio
Netherlands Institute for Radio Astronomy (ASTRON)
R. Vermeulen
Netherlands Institute for Radio Astronomy (ASTRON)
C. Vocks
Leibniz Association
R. J. van Weeren
Harvard-Smithsonian Center for Astrophysics
Ramj Wijers
University of Amsterdam
M. W. Wise
Netherlands Institute for Radio Astronomy (ASTRON)
University of Amsterdam
O. Wucknitz
Max Planck Society
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 584 A112Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Infrastructure
Onsala Space Observatory
DOI
10.1051/0004-6361/201526501