Browsing Research publications by Author "O'Sullivan, S. P."

Now showing items 1-16 of 16

    • 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, ...

    • Detection of magnetic fields in the circumgalactic medium of nearby galaxies using Faraday rotation 

      Heesen, V.; O'Sullivan, S. P.; Brüggen, M.; Basu, A.; Beck, R.; Seta, A.; Carretti, E.; Krause, M. G. H.; Haverkorn, M.; Hutschenreuter, S.; Bracco, A.; Stein, M.; Bomans, D. J.; Dettmar, R. -J.; Chyży, K. T.; Heald, G. H.; Paladino, R.; Horellou, C. (2023-02-24)
      Context. The existence of magnetic fields in the circumgalactic medium (CGM) is largely unconstrained. Their detection is important as magnetic fields can have a significant impact on the evolution of the CGM, and, in turn, ...

    • 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 ...

    • The Faraday Rotation Measure Grid of the LOFAR Two-metre Sky Survey: Data Release 2 

      O'Sullivan, S. P.; Shimwell, T. W.; Hardcastle, M. J.; Tasse, C.; Heald, G.; Carretti, E.; Brüggen, M.; Vacca, V.; Sobey, C.; Eck, C. L. Van; Horellou, C.; Beck, R.; Bilicki, M.; Bourke, S.; Botteon, A.; Croston, J. H.; Drabent, A.; Duncan, K.; Heesen, V.; Ideguchi, S.; Kirwan, M.; Lawlor, L.; Mingo, B.; Nikiel-Wroczyński, B.; Piotrowska, J.; Scaife, A. M. M.; Weeren, R. J. van (2023-01-02)
      A Faraday rotation measure (RM) catalogue, or RM Grid, is a valuable resource for the study of cosmic magnetism. Using the second data release (DR2) from the LOFAR Two-metre Sky Survey (LoTSS), we have produced a catalogue ...

    • Giant lobes of Centaurus A radio galaxy observed with the Suzaku X-ray satellite 

      Stawarz, L.; Tanaka, Y. T.; Madejski, G.; O'Sullivan, S. P.; Cheung, C. C.; Feain, I.J.; Fukazawa, Y.; Gandhi, P.; Hardcastle, M.J.; Kataoka, J.; Ostrowski, M.; Reville, B.; Siemiginowska, A.; Simionescu, A.; Takahashi, T.; Takei, Y.; Takeuchi, Y.; Werner, N. (2013-03-20)
      We report on Suzaku observations of selected regions within the southern giant lobe of the radio galaxy Centaurus A. In our analysis we focus on distinct X-ray features detected with the X-ray Imaging Spectrometer within ...

    • The intergalactic magnetic field probed by a giant radio galaxy 

      O'Sullivan, S. P.; Machalski, J.; Eck, C. L. Van; Heald, G.; Brueggen, M.; Fynbo, J. P. U.; Heintz, K. E.; Lara-Lopez, M. A.; Vacca, V.; Hardcastle, M. J.; Shimwell, T. W.; Tasse, C.; Vazza, F.; Andernach, H.; Birkinshaw, M.; Haverkorn, M.; Horellou, C.; Williams, W. L.; Harwood, J. J.; Brunetti, G.; Anderson, J. M.; Mao, S. A.; Nikiel-Wroczynski, B.; Takahashi, K.; Carretti, E.; Vernstrom, T.; Weeren, R. J. van; Orru, E.; Morabito, L. K.; Callingham, J. R. (2018-10-09)
      Cosmological simulations predict that an intergalactic magnetic field (IGMF) pervades the large scale structure (LSS) of the Universe. Measuring the IGMF is important to determine its origin (i.e. primordial or otherwise). ...

    • LOFAR Deep Fields : Probing a broader population of polarized radio galaxies in ELAIS-N1 

      Ruiz, N. Herrera; O'Sullivan, S. P.; Vacca, V.; Jelić, V.; Nikiel-Wroczyński, B.; Bourke, S.; Sabater, J.; Dettmar, R. -J.; Heald, G.; Horellou, C.; Piras, S.; Sobey, C.; Shimwell, T. W.; Tasse, C.; Hardcastle, M. J.; Kondapally, R.; Chyży, K. T.; Iacobelli, M.; Best, P. N.; Brüggen, M.; Carretti, E.; Prandoni, I. (2021-04-07)
      We present deep polarimetric observations of the European Large Area ISO Survey-North 1 (ELAIS-N1) field using the Low Frequency Array (LOFAR) at 114.9-177.4 MHz. The ELAIS-N1 field is part of the LOFAR Two-metre Sky Survey ...

    • The LOFAR Two Meter Sky Survey : Deep Fields Data Release 1, I -- Direction-dependent calibration and imaging 

      Tasse, C.; Shimwell, T.; Hardcastle, M. J.; O'Sullivan, S. P.; Weeren, R. van; Best, P. N.; Bester, L.; Hugo, B.; Smirnov, O.; Sabater, J.; Calistro-Rivera, G.; Gasperin, F. de; Morabito, L. K.; Röttgering, H.; Williams, W. L.; Bonato, M.; Bondi, M.; Botteon, A.; Brüggen, M.; Brunetti, G.; Chyży, K. T.; Garrett, M. A.; Gürkan, G.; Jarvis, M. J.; Kondapally, R.; Mandal, S.; Prandoni, I.; Repetti, A.; Retana-Montenegro, E.; Schwarz, D. J.; Shulevski, A.; Wiaux, Y. (2021-04-07)
      The Low Frequency Array (LOFAR) is an ideal instrument to conduct deep extragalactic surveys. It has a large field of view and is sensitive to large scale and compact emission. It is, however, very challenging to synthesize ...

    • The LOFAR Two-metre Sky Survey -- V. Second data release 

      Shimwell, T. W.; Hardcastle, M. J.; Tasse, C.; Best, P. N.; Röttgering, H. J. A.; Williams, W. L.; Botteon, A.; Drabent, A.; Mechev, A.; Shulevski, A.; Weeren, R. J. van; Bester, L.; Brüggen, M.; Brunetti, G.; Callingham, J. R.; Chyży, K. T.; Conway, J. E.; Dijkema, T. J.; Duncan, K.; Gasperin, F. de; Hale, C. L.; Haverkorn, M.; Hugo, B.; Jackson, N.; Mevius, M.; Miley, G. K.; Morabito, L. K.; Morganti, R.; Offringa, A.; Oonk, J. B. R.; Rafferty, D.; Sabater, J.; Smith, D. J. B.; Schwarz, D. J.; Smirnov, O.; O'Sullivan, S. P.; Vedantham, H.; White, G. J.; Albert, J. G.; Alegre, L.; Asabere, B.; Bacon, D. J.; Bonafede, A.; Bonnassieux, E.; Brienza, M.; Bilicki, M.; Bonato, M.; Rivera, G. Calistro; Cassano, R.; Cochrane, R.; Croston, J. H.; Cuciti, V.; Dallacasa, D.; Danezi, A.; Dettmar, R. J.; Gennaro, G. Di; Edler, H. W.; Enßlin, T. A.; Emig, K. L.; Franzen, T. M. O.; García-Vergara, C.; Grange, Y. G.; Gürkan, G.; Hajduk, M.; Heald, G.; Heesen, V.; Hoang, D. N.; Hoeft, M.; Horellou, C.; Iacobelli, M.; Jamrozy, M.; Jelić, V.; Kondapally, R.; Kukreti, P.; Kunert-Bajraszewska, M.; Magliocchetti, M.; Mahatma, V.; Małek, K.; Mandal, S.; Massaro, F.; Meyer-Zhao, Z.; Mingo, B.; Mostert, R. I. J.; Nair, D. G.; Nakoneczny, S. J.; Nikiel-Wroczyński, B.; Orrú, E.; Pajdosz-Śmierciak, U.; Pasini, T.; Prandoni, I.; Piggelen, H. E. van; Rajpurohit, K.; Retana-Montenegro, E.; Riseley, C. J.; Rowlinson, A.; Saxena, A.; Schrijvers, C.; Sweijen, F.; Siewert, T. M.; Timmerman, R.; Vaccari, M.; Vink, J.; West, J. L.; Wołowska, A.; Zhang, X.; Zheng, J. (2022-02-25)
      In this data release from the ongoing LOw-Frequency ARray (LOFAR) Two-metre Sky Survey we present 120a 168 MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m ...

    • The LOFAR Two-Metre Sky Survey : VI. Optical identifications for the second data release 

      Hardcastle, M. J.; Horton, M. A.; Williams, W. L.; Duncan, K. J.; Alegre, L.; Barkus, B.; Croston, J. H.; Dickinson, H.; Osinga, E.; Röttgering, H. J. A.; Sabater, J.; Shimwell, T. W.; Smith, D. J. B.; Best, P. N.; Botteon, A.; Brüggen, M.; Drabent, A.; Gasperin, F. de; Gürkan, G.; Hajduk, M.; Hale, C. L.; Hoeft, M.; Jamrozy, M.; Kunert-Bajraszewska, M.; Kondapally, R.; Magliocchetti, M.; Mahatma, V. H.; Mostert, R. I. J.; O'Sullivan, S. P.; Pajdosz-Śmierciak, U.; Petley, J.; Pierce, J. C. S.; Prandoni, I.; Schwarz, D. J.; Shulewski, A.; Siewert, T. M.; Stott, J. P.; Tang, H.; Vaccari, M.; Zheng, X.; Bailey, T.; Desbled, S.; Goyal, A.; Gonano, V.; Hanset, M.; Kurtz, W.; Lim, S. M.; Mielle, L.; Molloy, C. S.; Roth, R.; Terentev, I. A.; Torres, M. (2023-10-01)
      The second data release of the LOFAR Two-Metre Sky Survey (LoTSS) covers 27% of the northern sky, with a total area of ∼5700 deg1. The high angular resolution of LOFAR with Dutch baselines (6 arcsec) allows us to carry out ...

    • The LOFAR Two-metre Sky Survey Deep Fields: Data release 1. IV. Photometric redshifts and stellar masses 

      Duncan, K. J.; Kondapally, R.; Brown, M. J. I.; Best, P. N.; Röttgering, H. J. A.; Bondi, M.; Bowler, R. A. A.; Cochrane, R. K.; Gürkan, G.; Hardcastle, M. J.; Jarvis, M. J.; Kunert-Bajraszewska, M.; Leslie, S. K.; Małek, K.; Morabito, L. K.; O'Sullivan, S. P.; Prandoni, I.; Sabater, J.; Shimwell, T. W.; Smith, D. J. B.; Wang, L.; Wołowska, A. (2021-04-07)
      The Low Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS) is a sensitive, high-resolution 120-168 MHz survey split across multiple tiers over the northern sky. The first LoTSS Deep Fields data release consists of deep ...

    • The LOFAR Two-metre Sky Survey: Deep Fields: : II. The ELAIS-N1 LOFAR deep field 

      Sabater, J.; Best, P. N.; Tasse, C.; Hardcastle, M. J.; Shimwell, T. W.; Nisbet, D.; Jelic, V.; Callingham, J. R.; Rottgering, H. J. A.; Bonato, M.; Bondi, M.; Ciardi, B.; Cochrane, R. K.; Jarvis, M. J.; Kondapally, R.; Koopmans, L. V. E.; O'Sullivan, S. P.; Prandoni, I.; Schwarz, D. J.; Smith, D. J. B.; Wang, L.; Williams, W. L.; Zaroubi, S. (2021-04-07)
      The LOFAR Two-metre Sky Survey (LoTSS) will cover the full northern sky and, additionally, aims to observe the LoTSS deep fields to a noise level of ~10 microJy/bm over several tens of square degrees in areas that have the ...

    • Low-frequency observations of the Giant Radio Galaxy NGC 6251 

      Cantwell, T. M.; Bray, J. D.; Croston, J. H.; Scaife, A. M. M.; Mulcahy, D. D.; Best, P. N.; Bruggen, M.; Brunetti, G.; Callingham, J. R.; Clarke, A. O.; Hardcastle, M. J.; Harwood, J. J.; Heald, G.; Heesen, V.; Iacobelli, M.; Jamrozy, M.; Morganti, R.; Orru, E.; O'Sullivan, S. P.; Riseley, C. J.; Rottgering, H. J. A.; Shulevski, A.; Sridhar, S. S.; Tasse, C.; Eck, C. L. Van (2020-06-01)
      We present LOFAR observations at 150 MHz of the borderline FRI/FRII giant radio galaxy NGC 6251. This paper presents the most sensitive and highest resolution images of NGC 6251 at these frequencies to date, revealing for ...

    • Polarized point sources in the LOFAR Two-meter Sky Survey: A preliminary catalog 

      Eck, C. L. Van; Haverkorn, M.; Alves, M. I. R.; Beck, R.; Best, P.; Carretti, E.; Chyży, K. T.; Farnes, J. S.; Ferrière, K.; Hardcastle, M. J.; Heald, G.; Horellou, C.; Iacobelli, M.; Jelić, V.; Mulcahy, D. D.; O'Sullivan, S. P.; Polderman, I. M.; Reich, W.; Riseley, C. J.; Röttgering, H.; Schnitzeler, D. H. F. M.; Shimwell, T. W.; Vacca, V.; Vink, J.; White, G. J. (2018-06-01)
      The polarization properties of radio sources at very low frequencies (<200 MHz) have not been widely measured, but the new generation of low-frequency radio telescopes, including the Low Frequency Array (LOFAR: a Square ...

    • Possible discovery of Calvera's supernova remnant 

      Arias, M.; Botteon, A.; Bassa, C. G.; Jagt, S. van der; Weeren, R. J. van; O'Sullivan, S. P.; Bosschaart, Q.; Dullaart, R. S.; Hardcastle, M. J.; Hessels, J. W. T.; Shimwell, T.; Slob, M. M.; Sturm, J. A.; Tasse, C.; Theijssen, N. C. M. A.; Vink, J. (2022-11-01)
      We report the discovery of a ring of low surface brightness radio emission around the Calvera pulsar, a high Galactic latitude, isolated neutron star, in the LOFAR Two-metre Sky Survey (LoTSS). It is centered at α = ...

    • Radio-loud AGN in the first LoTSS data release: The lifetimes and environmental impact of jet-driven sources 

      Hardcastle, M. J.; Williams, W. L.; Best, P. N.; Croston, J. H.; Duncan, K. J.; Rottgering, H. J. A.; Sabater, J.; Shimwell, T. W.; Tasse, C.; Callingham, J. R.; Cochrane, R. K.; Gasperin, F. de; Gurkan, G.; Jarvis, M. J.; Mahatma, V.; Miley, G. K.; Mingo, B.; Mooney, S.; Morabito, L. K.; O'Sullivan, S. P.; Prandoni, I.; Shulevski, A.; Smith, D. J. B. (2018-11-19)
      We constructed a sample of 23,344 radio-loud active galactic nuclei (RLAGN) from the catalogue derived from the LOFAR Two-Metre Sky Survey (LoTSS) survey of the HETDEX Spring field. Although separating AGN from star-forming ...