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

被引：31

作者：

Orru, E. ^{[1
,2
]}

van Velzen, S. ^{[2
,3
]}

Pizzo, R. F. ^{[1
]}

Yatawatta, S. ^{[1
,4
]}

Paladino, R. ^{[5
,6
]}

Iacobelli, M. ^{[1
]}

Murgia, M. ^{[7
]}

Falcke, H. ^{[1
,2
,8
]}

Morganti, R. ^{[1
,4
]}

de Bruyn, A. G. ^{[1
,4
]}

Ferrari, C. ^{[9
]}

Anderson, J. ^{[10
]}

Bonafede, A. ^{[11
]}

Mulcahy, D. ^{[12
]}

Asgekar, A. ^{[1
,13
]}

Avruch, I. M. ^{[4
,14
]}

Beck, R. ^{[8
]}

Bell, M. E. ^{[15
]}

van Bemmel, I. ^{[1
,16
]}

Bentum, M. J. ^{[1
,17
]}

Bernardi, G. ^{[18
]}

Best, P. ^{[19
]}

Breitling, F. ^{[20
]}

Broderick, J. W. ^{[21
]}

Brueggen, M. ^{[11
]}

Butcher, H. R. ^{[22
]}

Ciardi, B. ^{[23
]}

Conway, J. E. ^{[24
]}

Corstanje, A. ^{[2
]}

de Geus, E. ^{[1
,25
]}

Deller, A. ^{[1
]}

Duscha, S. ^{[1
]}

Eisloeffel, J. ^{[26
]}

Engels, D. ^{[27
]}

Frieswijk, W. ^{[1
]}

Garrett, M. A. ^{[1
,28
]}

Griessmeier, J. ^{[29
,30
]}

Gunst, A. W. ^{[1
]}

Hamaker, J. P. ^{[1
]}

Heald, G. ^{[1
]}

Hoeft, M. ^{[26
]}

van der Horst, A. J. ^{[31
]}

Intema, H. ^{[28
,32
]}

Juette, E. ^{[33
]}

Kohler, J. ^{[8
]}

Kondratiev, V. I. ^{[2
,34
]}

Kuniyoshi, M. ^{[35
]}

Kuper, G. ^{[1
]}

Loose, M. ^{[1
]}

Maat, P. ^{[1
]}

机构：

[1] ASTRON, Netherlands Inst Radio Astron, NL-7990 AA Dwingeloo, Netherlands

[2] Radboud Univ Nijmegen, Dept Astrophys IMAPP, NL-6500 GL Nijmegen, Netherlands

[3] Johns Hopkins Univ, Dept Phys & Astron, Ctr Astrophys Sci, Baltimore, MD 21218 USA

[4] Univ Groningen, Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands

[5] Univ Bologna, Dept Phys & Astron, I-40127 Bologna, Italy

[6] INAF Osservatorio Radioastron, I-40129 Bologna, Italy

[7] INAF Osservatorio Astron Cagliari, I-09047 Selargius, CA, Italy

[8] Max Planck Inst Radioastron, D-53121 Bonn, Germany

[9] Univ Nice Sophia Antipolis, Observ Cote dAzur, Lab Lagrange, UMR 7293,CNRS, F-06300 Nice, France

[10] Helmholtz Zentrum Potsdam, Deutsch GeoForschungsZentrum GFZ, Dept Geodesy & Remote Sensing, D-14473 Potsdam, Germany

[11] Univ Hamburg, D-21029 Hamburg, Germany

[12] Univ Manchester, Sch Phys & Astron, Jodrell Bank Ctr Astrophys, Manchester M13 9PL, Lancs, England

[13] Shell Technol Ctr, Bangalore 560099, Karnataka, India

[14] SRON Netherlands Inst Space Res, NL-9700 AV Groningen, Netherlands

[15] CSIRO Australia Telescope Natl Facil, Epping, NSW 1710, Australia

[16] Joint Inst VLBI Europe, NL-7990 AA Dwingeloo, Netherlands

[17] Univ Twente, NL-7522 NB Enschede, Netherlands

[18] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA

[19] Univ Edinburgh, Royal Observ Edinburgh, Inst Astron, Edinburgh EH9 3HJ, Midlothian, Scotland

[20] Leibniz Inst Astrophys Potsdam AIP, D-14482 Potsdam, Germany

[21] Univ Southampton, Sch Phys & Astron, Southampton SO17 1BJ, Hants, England

[22] Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia

[23] Max Planck Inst Astrophys, D-85741 Garching, Germany

[24] Chalmers, Onsala Space Observ, Dept Earth & Space Sci, S-43992 Onsala, Sweden

[25] SmarterVision BV, NL-9401 JX Assen, Netherlands

[26] Thuringer Landessternwarte, D-07778 Tautenburg, Germany

[27] Hamburger Sternwarte, D-21029 Hamburg, Germany

[28] Leiden Univ, Leiden Observ, NL-2300 RA Leiden, Netherlands

[29] Univ Orleans, CNRS, LPC2E, F-45100 Orleans 2, France

[30] Univ Orleans, OSUC, Observ Paris, Stn Radioastron Nancay,CNRS,INSU,USR 704, F-18330 Nancay, France

[31] George Washington Univ, Dept Phys, Washington, DC 20052 USA

[32] Natl Radio Astron Observ, Charlottesville, VA 22903 USA

[33] Ruhr Univ Bochum, Astron Inst, D-44780 Bochum, Germany

[34] PN Lebedev Phys Inst, Ctr Astro Space, Moscow 117997, Russia

[35] Natl Astron Observ Japan, Mitaka, Tokyo 1818588, Japan

[36] Univ Amsterdam, Anton Pannekoek Inst, NL-1090 GE Amsterdam, Netherlands

[37] Univ Oulu, Sodankyla Geophys Observ, Sodankyla 99600, Finland

[38] Rutherford Appleton Lab, STFC, Didcot OX11 0QX, Oxon, England

[39] Univ Groningen, CIT, NL-9712 CP Groningen, Netherlands

[40] Observ Lyon, Ctr Rech Astrophys Lyon, F-69561 St Genis Laval, France

[41] Univ Oxford, Astrophys, Oxford OX1 3RH, England

[42] Univ Bielefeld, Fak Phys, D-33501 Bielefeld, Germany

[43] Rhodes Univ, Dept Phys & Elect, ZA-6140 Grahamstown, South Africa

[44] SKA South Africa, ZA-7405 Pinelands, South Africa

[45] Observ Paris, LESIA, CNRS, UMR 8109, F-92195 Meudon, France

来源：

ASTRONOMY & ASTROPHYSICS | 2015年 / 584卷

关键词：

instrumentation: interferometers; techniques: interferometric; galaxies: active; radiation mechanisms: non-thermal; radio continuum: galaxies; astroparticle physics; ACTIVE GALACTIC NUCLEI; DOUBLE-DOUBLE MORPHOLOGY; FREQUENCY SKY SURVEY; BLACK-HOLES; JET ACTIVITY; MINI-SURVEY; FEEDBACK; QUASAR; ARRAY; I;

D O I：

10.1051/0004-6361/201526501

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

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.

引用

页数：12