Browsing University of Hertfordshire by Author "Heald, George"

Now showing items 1-7 of 7

    • Exploring the making of a galactic wind in the star-bursting dwarf irregular galaxy IC 10 with LOFAR 

      Heesen, V.; Rafferty, D. A.; Horneffer, A.; Beck, R.; Basu, A.; Westcott, J.; Hindson, L.; Brinks, E.; Chyży, K. T.; Scaife, A. M. M.; Brüggen, M.; Heald, George; Fletcher, A.; Horellou, C.; Tabatabaei, F. S.; Paladino, R.; Nikiel-Wroczyński, B.; Hoeft, M.; Dettmar, R. -J. (2018-05-11)
      Low-mass galaxies are subject to strong galactic outflows, in which cosmic rays may play an important role; they can be best traced with low-frequency radio continuum observations, which are less affected by spectral ageing. ...

    • LOFAR and APERTIF Surveys of the Radio Sky : Probing Shocks and Magnetic Fields in Galaxy Clusters 

      Rottgering, Huub; Afonso, Jose; Barthel, Peter; Batejat, Fabien; Best, Philip; Bonafede, Annalisa; Brueggen, Marcus; Brunetti, Gianfranco; Chyzy, Krzysztof; Conway, John; De Gasperin, Francesco; Ferrari, Chiara; Haverkorn, Marijke; Heald, George; Hoeft, Matthias; Jackson, Neal; Jarvis, M.J.; Ker, Louise; Lehnert, Matt; Macario, Giulia; McKean, John; Miley, George; Morganti, Raffaella; Oosterloo, Tom; Orru, Emanuela; Pizzo, Roberto; Rafferty, David; Shulevski, Alexander; Tasse, Cyril; van Bemmel, Ilse; van der Tol, Bas; van Weeren, Reinout; Verheijen, Marc; White, Glenn; Wise, Michael (2011-12)
      At very low frequencies, the new pan-European radio telescope LOFAR is opening the last unexplored window of the electromagnetic spectrum for astrophysical studies. The revolutionary APERTIF-phased arrays that are about ...

    • LOFAR/H-ATLAS: The low-frequency radio luminosity - star-formation rate relation 

      Gurkan, Gulay; Hardcastle, Martin J.; Smith, Daniel; Best, Philip N.; Bourne, Nathan; Calistro-Rivera, Gabriela; Heald, George; Jarvis, Matt J.; Prandoni, Isabella; Rottgering, Huub J. A.; Sabater, Jose; Shimwell, Tim; Tasse, Cyril; Williams, Wendy L. (2018-04-11)
      Radio emission is a key indicator of star-formation activity in galaxies, but the radio luminosity-star formation relation has to date been studied almost exclusively at frequencies of 1.4 GHz or above. At lower radio ...

    • LoTSS/HETDEX: Optical quasars I. Low-frequency radio properties of optically selected quasars 

      Gürkan, Gülay; Hardcastle, Martin; Best, Philip; Morabito, Leah; Prandoni, Isabella; Jarvis, Matt; Duncan, Ken; Rivera, Gabriela Calistro; Callingham, Joe; Cochrane, Rachel; Croston, Judith; Heald, George; Mingo, Beatriz; Mooney, Sean; Sabater, Jose; Röttgering, Huub; Shimwell, Timothy; Smith, Dan; Tasse, Cyril; Williams, Wendy (2018-10-10)
      The radio-loud/radio-quiet (RL/RQ) dichotomy in quasars is still an open question. Although it is thought that accretion onto supermassive black holes in the centre the host galaxies of quasars is responsible for some radio ...

    • A low frequency study of linear polarization in radio galaxies 

      Mahatma, Vijay H.; Hardcastle, Martin J.; Harwood, Jeremy; O'Sullivan, Shane P.; Heald, George; Horellou, Cathy; Smith, Daniel J. B. (2020-12-26)
      Radio galaxies are linearly polarized -- an important property that allows us to infer the properties of the magnetic field of the source and its environment. However at low frequencies, Faraday rotation substantially ...

    • Signatures from a merging galaxy cluster and its AGN population : LOFAR observations of Abell 1682 

      Clarke, A. O.; Scaife, Anna M.M.; Shimwell, T.; Weeren, R. J. van; Bonafede, A.; Heald, George; Brunetti, G.; Cantwell, T. M.; Gasperin, F. de; Brüggen, M.; Botteon, A.; Hoeft, M.; Horellou, C.; Cassano, R.; Harwood, J. J.; Röttgering, H. J. A. (2019-07-05)
      We present LOFAR data from 110-180 MHz of the merging galaxy cluster Abell 1682, alongside archival optical, radio, and X-ray data. Our images of 6 arcsec in resolution at low frequencies reveal new structures associated ...

    • Sub-arcsecond imaging with the International LOFAR Telescope. II. Completion of the LOFAR Long-Baseline Calibrator Survey 

      Jackson, Neal; Badole, Shruti; Chhetri, Rajan; Prusis, Kaspars; Nikolajevs, Atvars; Morabito, Leah; Brentjens, Michiel; Sweijen, Frits; Iacobelli, Marco; Orrù, Emanuela; Sluman, J.; Blaauw, R.; Mulder, H.; Dijk, P. van; Mooney, Sean; Deller, Adam; Moldon, Javier; Callingham, J. R.; Harwood, Jeremy; Hardcastle, Martin; Heald, George; Drabent, Alexander; McKean, J. P.; Asgekar, A.; Avruch, I. M.; Bentum, M. J.; Bonafede, A.; Brouw, W. N.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Coolen, A.; Corstanje, A.; Damstra, S.; Duscha, S.; Eislöffel, J.; Falcke, H.; Garrett, M.; Gasperin, F. de; Griessmeier, J. -M.; Gunst, A. W.; Haarlem, M. P. van; Hoeft, M.; Horst, A. J. van der; Jütte, E.; Koopmans, L. V. E.; Krankowski, A.; Maat, P.; Mann, G.; Miley, G. K.; Nelles, A.; Norden, M.; Paas, M.; Pandey, V. N.; Pandey-Pommier, M.; Pizzo, R. F.; Reich, W.; Rothkaehl, H.; Rowlinson, A.; Ruiter, M.; Shulevski, A.; Schwarz, D. J.; Smirnov, O.; Tagger, M.; Vocks, C.; Weeren, R. J. van; Wijers, R.; Wucknitz, O.; Zarka, P.; Zensus, J. A.; Zucca, P. (2022-02-01)
      The Low-Frequency Array (LOFAR) Long-Baseline Calibrator Survey (LBCS) was conducted between 2014 and 2019 in order to obtain a set of suitable calibrators for the LOFAR array. In this paper, we present the complete survey, ...