Browsing University of Hertfordshire by Author "Mechev, A. P."

Now showing items 1-10 of 10

    • 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 ...

    • LOFAR discovery of a radio halo in the high-redshift galaxy cluster PSZ2 G099.86+58.45 

      Cassano, R.; Botteon, A.; Gennaro, G. Di; Brunetti, G.; Sereno, M.; Shimwell, T. W.; Weeren, R. J. van; Brüggen, M.; Gastaldello, F.; Izzo, L.; Bîrzan, L.; Bonafede, A.; Cuciti, V.; Gasperin, F. de; Rötttgering, H. J. A.; Hardcastle, M.; Mechev, A. P.; Tasse, C. (2019-08-19)
      In this Letter, we report the discovery of a radio halo in the high-redshift galaxy cluster PSZ2 G099.86+58.45 ($z=0.616$) with the LOw Frequency ARray (LOFAR) at 120-168 MHz. This is one of the most distant radio halos ...

    • LOFAR early-time search for coherent radio emission from GRB 180706A 

      Rowlinson, A.; Gourdji, K.; Meulen, K. van der; Meyers, Z. S.; Shimwell, T. W.; Veen, S. ter; Wijers, R. A. M. J.; Kuiack, M. J.; Shulevski, A.; Broderick, J. W.; Horst, A. J. van der; Tasse, C.; Hardcastle, M. J.; Mechev, A. P.; Williams, W. L. (2019-10-21)
      The nature of the central engines of gamma-ray bursts (GRBs) and the composition of their relativistic jets are still under debate. If the jets are Poynting flux dominated rather than baryon dominated, a coherent radio ...

    • The LOFAR Two-metre Sky Survey (LoTSS) III. First Data Release: optical/IR identifications and value-added catalogue 

      Williams, W. L.; Hardcastle, M. J.; Best, P. N.; Sabater, J.; Croston, J. H.; Duncan, K. J.; Shimwell, T. W.; Röttgering, H. J. A.; Nisbet, D.; Gürkan, G.; Alegre, L.; Cochrane, R. K.; Goyal, A.; Hale, C. L.; Jackson, N.; Jamrozy, M.; Kondapally, R.; Kunert-Bajraszewska, M.; Mahatma, V. H.; Mingo, B.; Morabito, L. K.; Prandoni, I.; Roskowinski, C.; Shulevski, A.; Smith, D. J. B.; Tasse, C.; Urquhart, S.; Webster, B.; White, G. J.; Beswick, R. J.; Callingham, J. R.; Chyży, K. T.; Gasperin, F. de; Harwood, J. J.; Hoeft, M.; Iacobelli, M.; McKean, J. P.; Mechev, A. P.; Miley, G. K.; Schwarz, D. J.; Weeren, R. J. van (2018-11-09)
      The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120-168 MHz survey of the Northern sky with diverse and ambitious science goals. Many of the scientific objectives of LoTSS rely upon, or are ...

    • The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release 

      Shimwell, T. W.; Röttgering, H. J. A.; Best, P. N.; Williams, W. L.; Dijkema, T. J.; Gasperin, F. de; Hardcastle, M. J.; Heald, G. H.; Hoang, D. N.; Horneffer, A.; Intema, H.; Mahony, E. K.; Mandal, S.; Mechev, A. P.; Morabito, L.; Oonk, J. B. R.; Rafferty, D.; Retana-Montenegro, E.; Sabater, J.; Tasse, C.; Weeren, R. J. van; Brüggen, M.; Brunetti, G.; Chyży, K. T.; Conway, J. E.; Haverkorn, M.; Jackson, N.; Jarvis, M. J.; McKean, J. P.; Miley, G. K.; Morganti, R.; White, G. J.; Wise, M. W.; Bemmel, I. M. van; Beck, R.; Brienza, M.; Bonafede, A.; Rivera, G. Calistro; Cassano, R.; Clarke, A. O.; Cseh, D.; Deller, A.; Drabent, A.; Driel, W. van; Engels, D.; Falcke, H.; Ferrari, C.; Fröhlich, S.; Garrett, M. A.; Harwood, J. J.; Heesen, V.; Hoeft, M.; Horellou, C.; Israel, F. P.; Kapińska, A. D.; Kunert-Bajraszewska, M.; McKay, D. J.; Mohan, N. R.; Orrú, E.; Pizzo, R. F.; Prandoni, I.; Schwarz, D. J.; Shulevski, A.; Sipior, M.; Smith, D. J. B.; Sridhar, S. S.; Steinmetz, M.; Stroe, A.; Varenius, E.; Werf, P. P. van der; Zensus, J. A.; Zwart, J. T. L. (2017-02-09)
      The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168 MHz imaging survey that will eventually cover the entire Northern sky. Each of the 3170 pointings will be observed for 8 hrs, which, at most declinations, is sufficient ...

    • The LOFAR Two-metre Sky Survey - II. First data release 

      Shimwell, T. W.; Tasse, C.; Hardcastle, M. J.; Mechev, A. P.; Williams, W. L.; Best, P. N.; Röttgering, H. J. A.; Callingham, J. R.; Dijkema, T. J.; Gasperin, F. de; Hoang, D. N.; Hugo, B.; Mirmont, M.; Oonk, J. B. R.; Prandoni, I.; Rafferty, D.; Sabater, J.; Smirnov, O.; Weeren, R. J. van; White, G. J.; Atemkeng, M.; Bester, L.; Bonnassieux, E.; Brüggen, M.; Brunetti, G.; Chyży, K. T.; Cochrane, R.; Conway, J. E.; Croston, J. H.; Danezi, A.; Duncan, K.; Haverkorn, M.; Heald, G. H.; Iacobelli, M.; Intema, H. T.; Jackson, N.; Jamrozy, M.; Jarvis, M. J.; Lakhoo, R.; Mevius, M.; Miley, G. K.; Morabito, L.; Morganti, R.; Nisbet, D.; Orrú, E.; Smith, D. J. B.; Harwood, J. J.; Heesen, V.; Mahatma, V.; Mingo, B. (2018-09-12)
      The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120-168MHz survey of the entire northern sky for which observations are now 20% complete. We present our first full-quality public data release. ...

    • The LOFAR Two-metre Sky Survey IV. First Data Release: Photometric redshifts and rest-frame magnitudes 

      Duncan, Kenneth J; Sabater, J.; Röttgering, H. J. A.; Jarvis, M. J.; Smith, D. J. B.; Best, P. N.; Callingham, J. R.; Cochrane, R.; Croston, J. H.; Hardcastle, M. J.; Mingo, B.; Morabito, L.; Nisbet, D.; Prandoni, I.; Shimwell, T. W.; Tasse, C.; White, G. J.; Williams, W. L.; Alegre, L.; Chyży, K. T.; Gürkan, G.; Hoeft, M.; Kondapally, R.; Mechev, A. P.; Miley, G. K.; Schwarz, D. J.; Weeren, R. J. van (2018-11-19)
      The LOFAR Two-metre Sky Survey (LoTSS) is a sensitive, high-resolution 120-168 MHz survey of the Northern sky. The LoTSS First Data Release (DR1) presents 424 square degrees of radio continuum observations over the HETDEX ...

    • The LoTSS view of radio AGN in the local Universe. The most massive galaxies are always switched on 

      Sabater, J.; Best, P.N.; Hardcastle, M. J.; Shimwell, T. W.; Tasse, C.; Williams, W. L.; Brüggen, M.; Cochrane, R. K.; Croston, J. H.; Gasperin, F. de; Duncan, K. J.; Gürkan, G.; Mechev, A. P.; Morabito, Leah K.; Prandoni, I.; Röttgering, H. J. A.; Smith, D. J. B.; Harwood, J. J.; Mingo, B.; Mooney, S.; Saxena, A. (2018-11-15)
      This paper presents a study of the local radio source population, by cross-comparing the data from the first data release (DR1) of the LOFAR Two-Metre Sky Survey (LoTSS) with the Sloan Digital Sky Survey (SDSS) DR7 main ...

    • LoTSS/HETDEX: Disentangling star formation and AGN activity in gravitationally-lensed radio-quiet quasars 

      Stacey, H. R.; McKean, J. P.; Jackson, N. J.; Best, P. N.; Rivera, G. Calistro; Callingham, J. R.; Duncan, K. J.; Gürkan, G.; Hardcastle, M. J.; Iacobelli, M.; Mechev, A. P.; Morabito, L. K.; Prandoni, I.; Röttgering, H. J. A.; Sabater, J.; Shimwell, T. W.; Tasse, C.; Williams, W. L. (2018-11-19)
      Determining the star-forming properties of radio-quiet quasars is important for understanding the co-evolution of star formation and black hole accretion. Here, we present the detection of the gravitationally-lensed ...

    • The origin of radio emission in broad absorption line quasars: Results from the LOFAR Two-metre Sky Survey 

      Morabito, L. K.; Matthews, J. H.; Best, P. N.; Gürkan, G.; Jarvis, M. J.; Prandoni, I.; Duncan, K. J.; Hardcastle, M. J.; Kunert-Bajraszewska, M.; Mechev, A. P.; Mooney, S.; Sabater, J.; Röttgering, H. J. A.; Shimwell, T. W.; Smith, D. J. B.; Tasse, C.; Williams, W. L. (2018-08-16)
      We present a study of the low-frequency radio properties of broad absorption line quasars (BALQSOs) from the LOFAR Two-metre Sky-Survey Data Release 1 (LDR1). The value-added LDR1 catalogue contains Pan-STARRS counterparts, ...