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Przejdź do strony domowej biblioteki Pedagogiczna Biblioteka Wojewódzka im. Komisji Edukacji Narodowej w Lublinie Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaPedagogiczna Biblioteka Wojewódzka im. Komisji Edukacji Narodowej w Lublinie
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    Wyświetlanie 1-10 z 10
    Tytuł:
    Radio continuum observations of the Leo Triplet at 2.64 GHz
    Autorzy:
    Weżgowiec, Marek
    Beck, R.
    Urbanik, Marek
    Soida, Marian
    Nikiel-Wroczyński, Błażej
    Adebahr, B.
    Bomans, D. J.
    Opis:
    Context. The Leo Triplet group of galaxies is best known for the impressive bridges of neutral gas that connect its members. One of the bridges forms a large tidal tail extending eastwards from NGC 3628 that hosts several H   i plumes and carries the material from this galaxy to the intergalactic space. Aims. The magnetic fields of the member galaxies NGC 3628 and NGC 3627 show morphological peculiarities, suggesting that interactions within the group may be caused by stripping of the magnetic field. This process could supply the intergalactic space with magnetised material, a scenario considered as a possible source of intergalactic magnetic fields (as seen eg. in the "Taffy" pairs of galaxies). Additionally, the plumes are likely to be the tidal dwarf galaxy candidates. Methods. We performed radio continuum mapping observations at 2.64 GHz using the 100-m Effelsberg radio telescope. We obtained total power and polarised intensity maps of the Triplet. These maps were analysed together with the archive data, and the magnetic field strength (as well as the magnetic energy density) was estimated. Results. Extended emission was not detected either in the total power or the polarised intensity maps. We obtained upper limits of the magnetic field strength and the energy density of the magnetic field in the Triplet. We detected emission from the easternmost clump and determined the strength of its magnetic field. In addition, we measured integrated fluxes of the member galaxies at 2.64 GHz and estimated their total magnetic field strengths. Conclusions. We found that the tidal tail hosts a tidal dwarf galaxy candidate that possesses a detectable magnetic field with a non-zero ordered component. Extended radio continuum emission, if present, is weaker than the reached confusion limit. The total magnetic field strength does not exceed 2.8 $\mu$G and the ordered component is lower than 1.6 $\mu$G.
    Dostawca treści:
    Repozytorium Uniwersytetu Jagiellońskiego
    Artykuł
    Tytuł:
    The low-frequency flattening of the radio spectrum of giant H II regions in M 101
    Autorzy:
    Bomans, D. J.
    Heesen, V.
    Pasini, T.
    Basu, A.
    Dénes, H.
    Brüggen, M.
    Edler, H. W.
    Weżgowiec, Marek
    Vohl, D.
    Gajović, L.
    de Gasperin, F.
    Adebahr, B.
    Horellou, C.
    Opis:
    Context. In galaxies, the flattening of the spectrum at low radio frequencies below 300 MHz has been the subject of some debate. A turnover at low frequencies could be caused by multiple physical processes, which can yield new insights into the properties of the ionised gas in the interstellar medium. Aims. We investigate the existence and nature of the low-frequency turnover in the H II regions of M 101. Methods. We study the nearby galaxy M 101 using the LOw Frequency ARray (LOFAR) at frequencies of 54 and 144 MHz, Apertif at 1370 MHz, and published combined map from the Very Large Array (VLA) and Effelesberg telescope at 4850 MHz. Results. The spectral index between 54 and 144 MHz is inverted at the centres of H II regions. We find a significant low-frequency flattening at the centres of five out of six H II regions that we selected for this study. Conclusions. The low frequency flattening in H II regions of M 101 can be explained with two different free-free absorption models. The flattening is localised in a region smaller than 1.5 kpc and can only be detected with high resolution (better than 45″). The detection of low frequency flattening has important consequences for using radio continuum observations below 100 MHz to measure extinction-free star-formation rates.
    Dostawca treści:
    Repozytorium Uniwersytetu Jagiellońskiego
    Artykuł
    Tytuł:
    CHANG-ES : XXVI. Insights into cosmic-ray transport from radio halos in edge-on galaxies
    Autorzy:
    Bomans, D. J.
    Heesen, V.
    Stein, Y.
    Paladino, R.
    Strong, A.
    Adebahr, B.
    Dettmar, R. -J.
    English, J.
    Vargas, C. J.
    Tabatabaei, F. S.
    Li, J.
    Beck, R.
    Stein, M.
    Chyży, Krzysztof
    Brüggen, M.
    Wiegert, T.
    Opis:
    Context. Galactic winds play a key role in regulating the evolution of galaxies over cosmic time. In recent years, the role of cosmic rays (CRs) in the formation of the galactic wind has increasingly gained attention. Therefore, we use radio continuum data to analyse the CR transport in edge-on galaxies. Aims. With newly reduced radio continuum data of five edge-on galaxies (NGC 891, NGC 3432, NGC 4013, NGC 4157, and NGC 4631), we plan to set new constraints on the morphology of radio halos and the physical properties of galactic winds driven by stellar feedback. By distinguishing between the central and outer regions of the galaxies, our study setup allows us to search for variations in the radio halo profile or CR transport along the galactic disk. Methods. Data from the LOFAR Two-metre Sky Survey (LoTSS) Data Release 2 at 144 MHz (HBA) and reprocessed data from the Very Large Array (VLA) at 1.5 GHz (L band) from the Continuum Halos in Nearby Galaxies – an EVLA Survey (CHANG-ES) enable us to increase the extent of the analysed radio continuum profile significantly (up to a factor of 2) compared to previous studies. We computed thermal emission maps using a mixture approach with Hα and near-infrared data, which were then subtracted to yield radio synchrotron emission maps. Then we compiled non-thermal spectral index maps and computed intensity profiles using a box integration approach. Lastly, we performed 1D CR transport modelling. Results. The non-thermal spectral index maps show evidence that the LoTSS maps are affected by thermal absorption in star-forming regions. The scale height analysis reveals that most of the galaxies are equally well fitted with a one-component instead of a two-component exponential profile. We find a bi-modality within our sample. While NGC 3432 and NGC 4013 have similar scale heights in the L band and HBA, the low-frequency scale heights of NGC 891, NGC 4157, and NGC 4631 exceed their high-frequency counterpart significantly. The 1D CR transport modelling shows agreement between the predicted magnetic field strength and the magnetic field strength estimates of equipartition measurements. Additionally, we find an increasing difference in wind velocities (with increasing height over the galactic disk) between the central and outer regions of the analysed galaxies.
    Dostawca treści:
    Repozytorium Uniwersytetu Jagiellońskiego
    Artykuł
    Tytuł:
    Subarcsecond international LOFAR radio images of the M82 nucleus at 118 MHz and 154 MHz
    Autorzy:
    Jackson, N.
    Wucknitz, O.
    Beswick, R.
    Haverkorn, M.
    Miley, G. K.
    Deller, A. T.
    Jarvis, M. J.
    Moldón, J.
    Heald, G.
    Toribio, M. C.
    White, G. J.
    Beck, R.
    Carozzi, T. D.
    Adebahr, B.
    Brüggen, M.
    Chyży, Krzysztof
    Aalto, S.
    Brunetti, G.
    Röttgering, H. J. A.
    Pérez-Torres, M. A.
    Dettmar, R.-J.
    Morabito, L. K.
    Horellou, C.
    Martí-Vidal, I.
    Varenius, E.
    Conway, J. E.
    Best, P.
    van Driel, W.
    Opis:
    Context. The nuclear starburst in the nearby galaxy M82 provides an excellent laboratory for understanding the physics of star formation. This galaxy has been extensively observed in the past, revealing tens of radio-bright compact objects embedded in a diffuse free-free absorbing medium. Our understanding of the structure and physics of this medium in M82 can be greatly improved by high-resolution images at low frequencies where the effects of free-free absorption are most prominent. Aims. The aims of this study are, firstly, to demonstrate imaging using international baselines of the Low Frequency Array (LOFAR), and secondly, to constrain low-frequency spectra of compact and diffuse emission in the central starburst region of M82 via high-resolution radio imaging at low frequencies. Methods. The international LOFAR telescope was used to observe M82 at 110−126 MHz and 146−162 MHz. Images were obtained using standard techniques from very long baseline interferometry. images were obtained at each frequency range: one only using international baselines, and one only using the longest Dutch (remote) baselines. Results. The 154 MHz image obtained using international baselines is a new imaging record in terms of combined image resolution (${0.3}′′$) and sensitivity ($\sigma = 0.15 mJy/beam$) at low frequencies (<327 MHz). We detected 16 objects at 154 MHz, six of these also at 118 MHz. Seven objects detected at 154 MHz have not been catalogued previously. For the nine objects previously detected, we obtained spectral indices and emission measures by fitting models to spectra (combining LOFAR with literature data). Four weaker but resolved features are also found: a linear (50 pc) filament and three other resolved objects, of which two show a clear shell structure. We do not detect any emission from either supernova 2008iz or from the radio transient source 43.78+59.3. The images obtained using remote baselines show diffuse emission, associated with the outflow in M82, with reduced brightness in the region of the edge-on star-forming disk.
    Dostawca treści:
    Repozytorium Uniwersytetu Jagiellońskiego
    Artykuł
    Tytuł:
    The LOFAR Multifrequency Snapshot Sky Survey (MSSS) : I. Survey description and first results
    Autorzy:
    Zarka, P.
    Schwarz, D.
    Cendes, Y.
    Sobey, C.
    Iacobelli, M.
    Hessels, J. W. T.
    Kokotanekov, G.
    Wijnholds, S.
    Vocks, C.
    Duscha, S.
    Butcher, H. R.
    Thoudam, S.
    Mevius, M.
    Beck, R.
    de Geus, E.
    Heesen, V.
    Bentum, M. J.
    Norden, M. J.
    van Weeren, R. J.
    Morganti, R.
    McFadden, R.
    Hamaker, J. P.
    Kuper, G.
    Macario, G.
    Hassall, T.
    Pandey-Pommier, M.
    Sendlinger, K.
    Vilchez, N.
    Rowlinson, A.
    Carbone, D.
    Clarke, A. O.
    McKay-Bukowski, D.
    Conway, J. E.
    Asgekar, A.
    van Velzen, S.
    Yatawatta, S.
    Daiboo, S.
    Avruch, I. M.
    Martin, P.
    Loose, M.
    van Leeuwen, J.
    Nikiel-Wroczyński, Błażej
    Brouw, W. N.
    Deller, A.
    Vermeulen, R.
    Stewart, A. J.
    Steinmetz, M.
    Stappers, B. W.
    Fallows, R. A.
    Riseley, C.
    Renting, A.
    Holties, H. A.
    Adebahr, B.
    de Vos, M.
    ter Veen, S.
    Frieswijk, W.
    de Bruyn, A. G.
    McKean, J. P.
    Best, P.
    Karastergiou, A.
    Wucknitz, O.
    Morabito, L. K.
    Kuniyoshi, M.
    Reich, W.
    Vogt, C.
    Gregson, J.
    Falcke, H.
    Toribio, M. C.
    Anderson, J.
    Tang, Y.
    Eislöffel, J.
    Noordam, J. E.
    Sluman, J.
    Kondratiev, V. I.
    Orrú, E.
    Intema, H.
    Nijboer, R.
    Hardcastle, M. J.
    Gunst, A. W.
    Bonafede, A.
    Sipior, M.
    Garrett, M. A.
    Tagger, M.
    Klijn, W. F. A.
    Hoeft, M.
    Ferrari, C.
    Dettmar, R.-J.
    Williams, W. L.
    Carroll, P.
    Engels, D.
    Pizzo, R. F.
    Cantwell, T.
    Jelić, V.
    Hörandel, J.
    Jütte, E.
    Trüstedt, J.
    de Gasperin, F.
    Bernardi, G.
    Brentjens, M.
    Ciardi, B.
    Jurusik, Wojciech
    Röttgering, H.
    Breton, R. P.
    Pandey, V. N.
    Rafferty, D.
    Breitling, F.
    Miller-Jones, J. C. A.
    Stroe, A.
    Mulcahy, D.
    Horneffer, A.
    Pietka, M.
    Markoff, S.
    Grießmeier, J.
    Bell, M. E.
    Shulevski, A.
    Tasse, C.
    Broderick, J.
    Law, C.
    Paas, H.
    Scheers, L. H. A.
    Kant, D.
    Wijers, R. A. M. J.
    Arts, M.
    Jones, D.
    Scaife, A. M. M.
    Croston, J.
    Pratley, L.
    Wise, M.
    Bray, J.
    Smirnov, O.
    Swinbank, J.
    Varenius, E.
    van Bemmel, I.
    Maat, P.
    Brüggen, M.
    Jackson, N. J.
    Sabater, J.
    van der Horst, A. J.
    Schoenmakers, A.
    Heald, G. H.
    Koopmans, L. V. E.
    Nelles, A.
    Offringa, A.
    Alexov, A.
    de Jong, A.
    Munk, H.
    Fender, R.
    Polatidis, A. G.
    Harwood, J.
    Bell, M. R.
    Dostawca treści:
    Repozytorium Uniwersytetu Jagiellońskiego
    Artykuł
      Wyświetlanie 1-10 z 10

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