Zobrazeno 1 - 10
of 276
pro vyhledávání: '"Callingham, J. R."'
Recent sensitive wide-field radio surveys, such as the LOFAR Two Meter Sky Survey (LoTSS), the LOFAR LBA Sky Survey (LoLSS), and the Very Large Array Sky Survey (VLASS), enable the selection of statistically large samples of peaked-spectrum (PS) sour
Externí odkaz:
http://arxiv.org/abs/2406.13346
Autor:
Osinga, E., van Weeren, R. J., Brunetti, G., Adam, R., Rajpurohit, K., Botteon, A., Callingham, J. R., Cuciti, V., de Gasperin, F., Miley, G. K., Röttgering, H. J. A., Shimwell, T. W.
Merging galaxy clusters often host spectacular diffuse radio synchrotron sources. These sources can be explained by a non-thermal pool of relativistic electrons accelerated by shocks and turbulence in the intracluster medium. The origin of the pool a
Externí odkaz:
http://arxiv.org/abs/2405.09384
Autor:
Groeneveld, C., van Weeren, R. J., Osinga, E., Williams, W. L., Callingham, J. R., de Gasperin, F., Botteon, A., Shimwell, T., de Jong, J. M. G. H. J., Jansen, L. F., Miley, G. K., Brunetti, G., Brüggen, M., Röttgering, H. J. A.
The largely unexplored decameter radio band (10-30 MHz) provides a unique window for studying a range of astronomical topics, such as auroral emission from exoplanets, inefficient cosmic ray acceleration mechanisms, fossil radio plasma, and free-free
Externí odkaz:
http://arxiv.org/abs/2405.05311
Autor:
Fitzmaurice, Evan, Stefánsson, Gudmundur, Kavanagh, Robert D., Mahadevan, Suvrath, Cañas, Caleb I., Winn, Joshua N., Robertson, Paul, Ninan, Joe P., Albrecht, Simon, Callingham, J. R., Cochran, William D., Delamer, Megan, Kanodia, Shubham, Lin, Andrea S. J., Marcussen, Marcus L., Pope, Benjamin J. S., Ramsey, Lawrence W., Roy, Arpita, Vedantham, Harish, Wright, Jason T.
We characterize the LHS 1610 system, a nearby ($d=9.7$ pc) M5 dwarf hosting a brown dwarf in a $10.6$ day, eccentric ($e \sim 0.37$) orbit. A joint fit of the available Gaia two-body solution, discovery radial velocities (RVs) from TRES, and new RVs
Externí odkaz:
http://arxiv.org/abs/2310.07827
Autor:
Gloudemans, A. J., Saxena, A., Intema, H., Callingham, J. R., Duncan, K. J., Rottgering, H. J. A., Belladitta, S., Hardcastle, M. J., Harikane, Y., Spingola, C.
Publikováno v:
A&A 678, A128 (2023)
We present the low-frequency radio spectra of 9 high-redshift quasars at $5.6 \leq z \leq 6.6$ using the Giant Metre Radio Telescope band-3, -4, and -5 observations ($\sim$300-1200 MHz), archival Low Frequency Array (LOFAR; 144 MHz), and Very Large A
Externí odkaz:
http://arxiv.org/abs/2309.03936
Autor:
Gloudemans, A. J., Callingham, J. R., Duncan, K. J., Saxena, A., Harikane, Y., Hill, G. J., Zeimann, G. R., Rottgering, H. J. A., Hardcastle, M. J., Pineda, J. S., Shimwell, T. W., Smith, D. J. B., Wagenveld, J. D.
Publikováno v:
A&A 678, A161 (2023)
We present the serendipitous discovery of 8 distant ($>$ 50 pc) late M dwarfs with plausible associated radio emission at 144 MHz. The M dwarf nature of our sources has been confirmed with optical spectroscopy performed using HET/LRS2 and Subaru/FOCA
Externí odkaz:
http://arxiv.org/abs/2309.01741
Autor:
de Gasperin, F., Edler, H. W., Williams, W. L., Callingham, J. R., Asabere, B., Bruggen, M., Brunetti, G., Dijkema, T. J., Hardcastle, M. J., Iacobelli, M., Offringa, A., Norden, M. J., Rottgering, H. J. A., Shimwell, T., van Weeren, R. J., Tasse, C., Bomans, D. J., Bonafede, A., Botteon, A., Cassano, R., Chyzy, K. T., Cuciti, V., Emig, K. L., Kadler, M., Miley, G., Mingo, B., Oei, M. S. S. L., Prandoni, I., Schwarz, D. J., Zarka, P.
Publikováno v:
A&A 673, A165 (2023)
The Low Frequency Array (LOFAR) is the only existing radio interferometer able to observe at ultra-low frequencies (<100 MHz) with high resolution (<15") and high sensitivity (<1 mJy/beam). To exploit these capabilities, the LOFAR Surveys Key Science
Externí odkaz:
http://arxiv.org/abs/2301.12724
Autor:
Vedantham, H. K., Dupuy, Trent J., Evans, E. L., Sanghi, A., Callingham, J. R., Shimwell, T. W., Best, W. M. J., Liu, M. C., Zarka, P.
Publikováno v:
A&A 675, L6 (2023)
Brown dwarfs display Jupiter-like auroral phenomena such as magnetospheric H$\alpha$ emission and coherent radio emission. Coherent radio emission is a probe of magnetospheric acceleration mechanisms and provides a direct measurement of the magnetic
Externí odkaz:
http://arxiv.org/abs/2301.01003
Spectral variability offers a new technique to identify small scale structures from scintillation, as well as determining the absorption mechanism for peaked-spectrum (PS) radio sources. In this paper, we present very long baseline interferometry (VL
Externí odkaz:
http://arxiv.org/abs/2301.00977
Autor:
Callingham, J. R., Shimwell, T. W., Vedantham, H. K., Bassa, C. G., O'Sullivan, S. P., Yiu, T. W. H., Bloot, S., Best, P. N., Hardcastle, M. J., Haverkorn, M., Kavanagh, R. D., Lamy, L., Pope, B. J. S., Röttgering, H. J. A., Schwarz, D. J., Tasse, C., van Weeren, R. J., White, G. J., Zarka, P., Bomans, D. J., Bonafede, A., Bonato, M., Botteon, A., Bruggen, M., Chyży, K. T., Drabent, A., Emig, K. L., Gloudemans, A. J., Gürkan, G., Hajduk, M., Hoang, D. N., Hoeft, M., Iacobelli, M., Kadler, M., Kunert-Bajraszewska, M., Mingo, B., Morabito, L. K., Nair, D. G., Pérez-Torres, M., Ray, T. P., Riseley, C. J., Rowlinson, A., Shulevski, A., Sweijen, F., Timmerman, R., Vaccari, M., Zheng, J.
Publikováno v:
A&A 670, A124 (2023)
We present the detection of 68 sources from the most sensitive radio survey in circular polarisation conducted to date. We use the second data release of the 144 MHz LOFAR Two-metre Sky Survey to produce circularly-polarised maps with median 140 $\mu
Externí odkaz:
http://arxiv.org/abs/2212.09815