Browsing by Author "Röttgering, H. J. A."

Now showing items 1-20 of 56

    • Accretion mode versus radio morphology in the LOFAR Deep Fields 

      Mingo, B.; Croston, J. H.; Best, P. N.; Duncan, K. J.; Hardcastle, M. J.; Kondapally, R.; Prandoni, I.; Sabater, J.; Shimwell, T. W.; Williams, W. L.; Baldi, R. D.; Bonato, M.; Bondi, M.; Dabhade, P.; Gürkan, G.; Ineson, J.; Magliocchetti, M.; Miley, G.; Pierce, J. C. S.; Röttgering, H. J. A. (2022-02-16)
      Radio-loud active galaxies have two accretion modes [radiatively inefficient (RI) and radiatively efficient (RE)], with distinct optical and infrared signatures, and two jet dynamical behaviours, which in arcsec- to ...

    • Alignment in the orientation of LOFAR radio sources 

      Osinga, E.; Miley, G. K.; Weeren, R. J. van; Shimwell, T. W.; Duncan, K. J.; Hardcastle, M. J.; Mechev, A. P.; Röttgering, H. J. A.; Tasse, C.; Williams, W. L. (2020-08-25)
      Various studies have laid claim to finding an alignment of the polarization vectors or radio jets of active galactic nuclei (AGN) over large distances, but these results have proven controversial and so far, there is no ...

    • The Application of Ridgelines in Extended Radio Source Cross-Identification 

      Barkus, B.; Croston, J. H.; Piotrowska, J.; Mingo, B.; Best, P. N.; Hardcastle, M. J.; Mostert, R. I. J.; Röttgering, H. J. A.; Sabater, J.; Webster, B.; Williams, W. L. (2021-10-22)
      Extended radio sources are an important minority population in modern deep radio surveys, because they enable detailed investigation of the physics governing radio-emitting regions such as active galaxies and their ...

    • The beautiful mess in Abell 2255 

      Botteon, A.; Brunetti, G.; Weeren, R. J. van; Shimwell, T. W.; Pizzo, R. F.; Cassano, R.; Iacobelli, M.; Gastaldello, F.; Bîrzan, L.; Bonafede, A.; Brüggen, M.; Cuciti, V.; Dallacasa, D.; Gasperin, F. de; Gennaro, G. Di; Drabent, A.; Hardcastle, M. J.; Hoeft, M.; Mandal, S.; Röttgering, H. J. A.; Simionescu, A. (2020-07-07)
      We present LOFAR observations of one of the most spectacular objects in the radio sky: Abell 2255. This is a nearby ($z = 0.0806$) merging galaxy cluster hosting one of the first radio halos ever detected in the intra-cluster ...

    • Blazars in the LOFAR Two-Metre Sky Survey First Data Release 

      Mooney, S.; Quinn, J.; Callingham, J. R.; Morganti, R.; Duncan, K.; Morabito, Leah K.; Best, P. N.; Gürkan, G.; Hardcastle, M. J.; Prandoni, I.; Röttgering, H. J. A.; Sabater, J.; Shimwell, T. W.; Shulevski, A.; Tasse, C.; Williams, W. L. (2018-11-19)
      Historically, the blazar population has been poorly understood at low frequencies because survey sensitivity and angular resolution limitations have made it difficult to identify megahertz counterparts. We used the LOFAR ...

    • Coherent radio emission from a quiescent red dwarf indicative of star-planet interaction 

      Vedantham, H. K.; Callingham, J. R.; Shimwell, T. W.; Tasse, C.; Pope, B. J. S.; Bedell, M.; Snellen, I.; Best, P.; Hardcastle, M. J.; Haverkorn, M.; Mechev, A.; O'Sullivan, S. P.; Röttgering, H. J. A.; White, G. J. (2020-02-17)
      Low-frequency (ν ≲ 150 MHz) stellar radio emission is expected to originate in the outer corona at heights comparable to and larger than the stellar radius. Such emission from the Sun has been used to study coronal structure, ...

    • Cosmic evolution of low-excitation radio galaxies in the LOFAR Two-meter Sky Survey Deep Fields 

      Kondapally, R.; Best, P. N.; Cochrane, R. K.; Sabater, J.; Duncan, K. J.; Hardcastle, M. J.; Haskell, P.; Mingo, B.; Röttgering, H. J. A.; Smith, D. J. B.; Williams, W. L.; Bonato, M.; Rivera, G. Calistro; Gao, F.; Hale, C. L.; Małek, K.; Miley, G. K.; Prandoni, I.; Wang, L. (2022-04-26)
      Feedback from low-excitation radio galaxies (LERGs) plays a key role in the lifecycle of massive galaxies in the local Universe; their evolution, and the impact of these active galactic nuclei on early galaxy evolution, ...

    • Cosmic evolution of radio-AGN feedback: confronting models with data 

      Kondapally, R.; Best, P. N.; Raouf, M.; Thomas, N. L.; Davé, R.; Shabala, S. S.; Röttgering, H. J. A.; Hardcastle, M. J.; Bonato, M.; Cochrane, R. K.; Małek, K.; Morabito, L. K.; Prandoni, I.; Smith, D. J. B. (2023-08-30)
      Radio-mode feedback is a key ingredient in galaxy formation and evolution models, required to reproduce the observed properties of massive galaxies in the local Universe. We study the cosmic evolution of radio-active ...

    • Diffuse Radio Emission from Galaxy Clusters in the LOFAR Two-metre Sky Survey Deep Fields 

      Osinga, E.; Weeren, R. J. van; Boxelaar, J.; Brunetti, G.; Botteon, A.; Brüggen, M.; Shimwell, T. W.; Bonafede, A.; Best, P. N.; Bonato, M.; Cassano, R.; Gastaldello, F.; Gennaro, G. di; Hardcastle, M. J.; Mandal, S.; Rossetti, M.; Röttgering, H. J. A.; Sabater, J. (2021-04-07)
      Low-frequency radio observations are revealing an increasing number of diffuse synchrotron sources from galaxy clusters, dominantly in the form of radio halos or radio relics. The existence of this diffuse synchrotron ...

    • The environments of radio-loud AGN from the LOFAR Two-Metre Sky Survey (LoTSS) 

      Croston, J. H.; Hardcastle, M. J.; Mingo, B.; Best, P. N.; Sabater, J.; Shimwell, T. W.; Williams, W. L.; Duncan, K. J.; Röttgering, H. J. A.; Brienza, M.; Gürkan, G.; Ineson, J.; Morabito, L. M.; Miley, G. K.; O'Sullivan, S. P.; Prandoni, I. (2018-10-10)
      An understanding of the relationship between radio-loud active galaxies and their large-scale environments is essential for realistic modelling of radio-galaxy evolution and environmental impact, for understanding AGN ...

    • Extragalactic Peaked-Spectrum Radio Sources at Low-Frequencies are Young Radio Galaxies 

      Slob, M. M.; Callingham, J. R.; Röttgering, H. J. A.; Williams, W. L.; Duncan, K. J.; Gasperin, F. de; Hardcastle, M. J.; Miley, G. K. (2022-12-20)
      We present a sample of 373 peaked-spectrum (PS) sources with spectral peaks around 150 MHz, selected using a subset of the two LOw Frequency ARray (LOFAR) all-sky surveys, the LOFAR Two Meter Sky Survey and the LOFAR LBA ...

    • The galaxy group NGC 507: newly detected AGN remnant plasma transported by sloshing 

      Brienza, M.; Lovisari, L.; Rajpurohit, K.; Bonafede, A.; Gastaldello, F.; Murgia, M.; Vazza, F.; Bonnassieux, E.; Botteon, A.; Brunetti, G.; Drabent, A.; Hardcastle, M. J.; Pasini, T.; Riseley, C. J.; Röttgering, H. J. A.; Shimwell, T.; Simionescu, A.; Weeren, R. J. van (2022-05-06)
      Jets from active galactic nuclei (AGN) are known to recurrently enrich their surrounding medium with mildly-relativistic particles and magnetic fields. Here, we present a detailed multi-frequency analysis of the nearby ...

    • The great Kite in the sky: a LOFAR observation of the radio source in Abell 2626 

      Ignesti, A.; Shimwell, T.; Brunetti, G.; Gitti, M.; Intema, H.; Weeren, R. J. van; Hardcastle, M. J.; Clarke, A. O.; Botteon, A.; Gennaro, G. Di; Brüggen, M.; Browne, I.; Mandal, S.; Röttgering, H. J. A.; Cuciti, V.; Gasperin, F. de; Cassano, R.; Scaife, Anna M.M. (2020-09-29)
      The radio source at the center of the galaxy cluster Abell 2626, also known as the Kite, stands out for its unique morphology composed of four, symmetric arcs. Previous studies have probed the properties of this source at ...

    • The High-redshift Clusters Occupied by Bent Radio AGN (COBRA) Survey: Investigating the Role of Environment on Bent Radio AGNs Using LOFAR 

      Golden-Marx, Emmet; Moravec, E.; Shen, L.; Cai, Z.; Blanton, E. L.; Gendron-Marsolais, M. L.; Röttgering, H. J. A.; Weeren, R. J. van; Buiten, V.; Grumitt, R. D. P.; Golden-Marx, J.; Pinjarkar, S.; Tang, H. (2023-10-13)
      Bent radio active galactic nucleus (AGN) morphology depends on the density of the surrounding gas. However, bent sources are found inside and outside clusters, raising the question of how environment impacts bent AGN ...

    • The life cycle of radio galaxies in the LOFAR Lockman Hole field 

      Jurlin, N.; Morganti, R.; Brienza, M.; Mandal, S.; Maddox, N.; Duncan, K. J.; Shabala, S. S.; Hardcastle, M. J.; Prandoni, I.; Röttgering, H. J. A.; Mahatma, V.; Best, P. N.; Mingo, B.; Sabater, J.; Shimwell, T. W.; Tasse, C. (2020-06-08)
      Radio galaxies are known to go through cycles of activity, where phases of apparent quiescence can be followed by repeated activity of the central supermassive black hole. A better understanding of this cycle is crucial ...

    • Link between radio-loud AGNs and host-galaxy shape 

      Zheng, X. C.; Röttgering, H. J. A.; Best, P. N.; Wel, A. van der; Hardcastle, M. J.; Williams, W. L.; Bonato, M.; Prandoni, I.; Smith, D. J. B.; Leslie, S. K. (2020-10-15)
      The morphology of quiescent galaxies has been found to be correlated with the activity of their central super massive black hole. In this work, we use data from the first data release of the LOFAR Two$-$Metre Sky Survey ...

    • The Lockman Hole project : LOFAR observations and spectral index properties of low-frequency radio sources 

      Mahony, E. K.; Morganti, R.; Prandoni, I.; Bemmel, I. M. van; Shimwell, T. W.; Brienza, M.; Best, P. N.; Brüggen, M.; Rivera, G. Calistro; Gasperin, F. de; Hardcastle, M. J.; Harwood, J. J.; Heald, G.; Jarvis, M. J.; Mandal, S.; Miley, G. K.; Retana-Montenegro, E.; Röttgering, H. J. A.; Sabater, J.; Tasse, C.; Velzen, S. van; Weeren, R. J. van; Williams, W. L.; White, G. J. (2016-12-11)
      The Lockman Hole is a well-studied extragalactic field with extensive multi-band ancillary data covering a wide range in frequency, essential for characterising the physical and evolutionary properties of the various source ...

    • LOFAR 144-MHz follow-up observations of GW170817 

      Broderick, J. W.; Shimwell, T. W.; Gourdji, K.; Rowlinson, A.; Nissanke, S.; Hotokezaka, K.; Jonker, P. G.; Tasse, C.; Hardcastle, M. J.; Oonk, J. B. R.; Fender, R. P.; Wijers, R. A. M. J.; Shulevski, A.; Stewart, A. J.; Veen, S. ter; Moss, V. A.; Wiel, M. H. D. van der; Nichols, D. A.; Piette, A.; Carbone, D.; Corbel, S.; Eislöffel, J.; Grießmeier, J. -M.; Keane, E. F.; Law, C. J.; Muñoz-Darias, T.; Pietka, M.; Serylak, M.; Horst, A. J. van der; Leeuwen, J. van; Wijnands, R.; Zarka, P.; Anderson, J. M.; Bentum, M. J.; Blaauw, R.; Brouw, W. N.; Brüggen, M.; Ciardi, B.; Vos, M. de; Duscha, S.; Fallows, R. A.; Franzen, T. M. O.; Garrett, M. A.; Gunst, A. W.; Hoeft, M.; Hörandel, J. R.; Iacobelli, M.; Jütte, E.; Koopmans, L. V. E.; Krankowski, A.; Maat, P.; Mann, G.; Mulder, H.; Nelles, A.; Paas, H.; Pandey-Pommier, M.; Pekal, R.; Reich, W.; Röttgering, H. J. A.; Schwarz, D. J.; Smirnov, O.; Soida, M.; Toribio, M. C.; Haarlem, M. P. van; Weeren, R. J. van; Vocks, C.; Wucknitz, O.; Zucca, P. (2020-06-01)
      We present low-radio-frequency follow-up observations of AT 2017gfo, the electromagnetic counterpart of GW170817, which was the first binary neutron star merger to be detected by Advanced LIGO-Virgo. These data, with a ...

    • LOFAR 150-MHz observations of the Boötes field: Catalogue and Source Counts 

      Williams, W. L.; Van Weeren, R. J.; Röttgering, H. J. A.; Best, P.; Dijkema, T. J.; Gasperin, F. de; Hardcastle, M. J.; Heald, G.; Prandoni, I.; Sabater, J.; Shimwell, T. W.; Tasse, C.; Bemmel, I. M. van; Brüggen, M.; Brunetti, G.; Conway, J. E.; Enßlin, T.; Engels, D.; Falcke, H.; Ferrari, C.; Haverkorn, M.; Jackson, N.; Jarvis, M. J.; Kapinska, A. D.; Mahony, E. K.; Miley, G. K.; Morabito, L. K.; Morganti, R.; Orrú, E.; Retana-Montenegro, E.; Sridhar, S. S.; Toribio, M. C.; White, G. J.; Wise, M. W.; Zwart, J. T. L. (2016-08-11)
      We present the first wide area (19 deg$^2$), deep ($\approx120-150$ {\mu}Jy beam$^{-1}$), high resolution ($5.6 \times 7.4$ arcsec) LOFAR High Band Antenna image of the Bo\"otes field made at 130-169 MHz. This image is at ...

    • LOFAR facet calibration 

      Van Weeren, R. J.; Williams, W. L.; Hardcastle, M.J.; Shimwell, T. W.; Rafferty, D. A.; Sabater, J.; Heald, G.; Sridhar, S. S.; Dijkema, T. J.; Brunetti, G.; Brüggen, M.; Andrade-Santos, F.; Ogrean, G. A.; Röttgering, H. J. A.; Dawson, W. A.; Forman, W.R.; Gasperin, F. de; Jones, C.; Miley, G.K.; Rudnick, L.; Sarazin, C.L.; Bonafede, A.; Best, P. N.; Bîrzan, L.; Cassano, R.; Chyży, K. T.; Croston, J. H.; Ensslin, T.; Ferrari, C.; Hoeft, M.; Horellou, C.; Jarvis, M.J.; Kraft, R.P.; Mevius, M.; Intema, H. T.; Murray, S. S.; Orrú, E.; Pizzo, R.; Simionescu, A.; Stroe, A.; Tol, S. van der; White, G.J. (2016-03-07)
      LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of the low-frequency radio sky. At the same time LOFAR also provides ...