Wide-field LOFAR imaging of the field around the double-double radio galaxy B1834+620 A fresh view on a restarted AGN and doubeltjes
Wide-field LOFAR imaging of the field around the double-double radio galaxy B1834+620 A fresh view on a restarted AGN and doubeltjes
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双双射电星系 B1834 620 周围场的宽视场 LOFAR 成像 重新启动的 AGN 和 doubeltjes 的新视角
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
O. Wucknitz
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文献类型：
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作者：
E. Orrù;E. Orrù;S. Velzen;S. Velzen;R. Pizzo;S. Yatawatta;S. Yatawatta;R. Paladino;R. Paladino;M. Iacobelli;M. Murgia;H. Falcke;H. Falcke;H. Falcke;R. Morganti;R. Morganti;A. Bruyn;A. Bruyn;C. Ferrari;James M. Anderson;A. Bonafede;D. Mulcahy;A. Asgekar;A. Asgekar;I. Avruch;R. Beck;Morag Bell;I. V. Bemmel;I. V. Bemmel;M. Bentum;M. Bentum;G. Bernardi;P. Best;F. Breitling;J. Broderick;M. Brüggen;H. Butcher;B. Ciardi;J. Conway;A. Corstanje;E. D. Geus;A. Deller;S. Duscha;J. Eislöffel;D. Engels;W. Frieswijk;M. A. Garrett;M. A. Garrett;J. Grießmeier;A. Gunst;J. Hamaker;G. Heald;M. Hoeft;A. V. D. Horst;H. Intema;H. Intema;E. Juette;J. Kohler;V. Kondratiev;V. Kondratiev;M. Kuniyoshi;G. Kuper;M. Loose;P. Maat;G. Mann;S. Markoff;R. McFadden;D. McKay;D. McKay;G. Miley;J. Moldón;G. Molenaar;H. Munk;A. Nelles;H. Paas;M. Pandey;V. Pandey;G. Pietka;A. Polatidis;W. Reich;H. Röttgering;A. Rowlinson;A. Scaife;A. Schoenmakers;D. Schwarz;M. Serylak;A. Shulevski;A. Shulevski;O. Smirnov;M. Steinmetz;A. I. F. Stewart;J. Swinbank;M. Tagger;C. Tasse;S. Thoudam;M. C. Toribio;R. Vermeulen;C. Vocks;R. Weeren;R. Wijers;M. Wise;M. Wise;O. Wucknitz
上下文双-双射电星系（DDRGs）的存在是AGN中经常性喷流活动的证据，正如标准吸积模型所预期的那样。详细研究这些罕见的来源提供了新的视角，调查活动星系核的占空比，活动星系核星系反馈，吸积机制。另一方面，大量的射电源目录提供了关于射电大活动星系核向高红移演化的统计信息。目标。使用LOFAR望远镜的宽视场成像，我们研究了一个著名的DDRG以及大量的射电源的视野。方法.我们提出了一个高分辨率的图像DDRG B1834+620在144 MHz使用LOFAR调试数据。我们的图像覆盖约100平方度，包含1000多个源。结果DDRG B1834+620的四个分量首次在144 MHz下得到解析。内叶被发现指向外叶的方向，不像标准FR II源。在北方的外叶探测到+60 rad m −2的偏振辐射。高空间分辨率允许识别大量的小型双瓣射电源;在该领域的所有源中，大约有10%是间隔小于1的双瓣射电源。结论.四个分量的光谱拟合与外叶仍然活跃或喷流最近关闭的情况一致，而内叶的排放是新旧喷流活动混合的结果。从DDRG内叶中新扩展的特征的存在，我们可以推断，负责其形成的机制是由新发射的射流驱动的弓形激波。我们发现，在1.4 GHz的小双打的密度超过FR II源具有类似的属性的密度，但这种差异变得更小的低通量密度。最后，我们证明了宽视场成像的重大挑战（例如，光束的时间和频率变化，方向相关的校准误差）可以使用LOFAR调试数据解决，从而证明了完整的LOFAR望远镜发现数百万个红移z = 1的强大AGN的潜力。
Context. The existence of double-double radio galaxies (DDRGs) is evidence for recurrent jet activity in 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.
影响因子：
6.5
作者：
van Haarlem, M. P.;Wise, M. W.;van Zwieten, J.
通讯作者：
van Zwieten, J.