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7 results on '"Veen, S. t."'

1. LOFAR discovery of a quiet emission mode in PSR B0823+26

Author

Sobey, C., Young, N. J., Hessels, J. W. T., Weltevrede, P., Noutsos, A., Stappers, B. W., Kramer, M., Bassa, C., Lyne, A. G., Kondratiev, V. I., Hassall, T. E., Keane, E. F., Bilous, A. V., Breton, R. P., Grießmeier, J. -M, Karastergiou, A., Pilia, M., Serylak, M., Veen, S. t., van Leeuwen, J., Alexov, A., Anderson, J., Asgekar, A., Avruch, I. M., Bell, M. E., Bentum, M. J., Bernardi, G., Best, P., Bîrzan, L., Bonafede, A., Breitling, F., Broderick, J., Brüggen, M., Corstanje, A., Carbone, D., de Geus, E., de Vos, M., van Duin, A., Duscha, S., Eislöffel, J., Falcke, H., Fallows, R. A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., Gunst, A. W., Hamaker, J. P., Heald, G., Hoeft, M., Hörandel, J., Jütte, E., Kuper, G., Maat, P., Mann, G., Markoff, S., McFadden, R., McKay-Bukowski, D., McKean, J. P., Mulcahy, D. D., Munk, H., Nelles, A., Norden, M. J., Orrù, E., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pietka, G., Pizzo, R., Polatidis, A. G., Rafferty, D., Renting, A., Röttgering, H., Rowlinson, A., Scaife, A. M. M., Schwarz, D., Sluman, J., Smirnov, O., Steinmetz, M., Stewart, A., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Thoudam, Satyendra, Toribio, C., Vermeulen, R., Vocks, C., van Weeren, R. J., Wijers, R. A. M. J., Wise, M. W., Wucknitz, O., Yatawatta, S., Zarka, P., Sobey, C., Young, N. J., Hessels, J. W. T., Weltevrede, P., Noutsos, A., Stappers, B. W., Kramer, M., Bassa, C., Lyne, A. G., Kondratiev, V. I., Hassall, T. E., Keane, E. F., Bilous, A. V., Breton, R. P., Grießmeier, J. -M, Karastergiou, A., Pilia, M., Serylak, M., Veen, S. t., van Leeuwen, J., Alexov, A., Anderson, J., Asgekar, A., Avruch, I. M., Bell, M. E., Bentum, M. J., Bernardi, G., Best, P., Bîrzan, L., Bonafede, A., Breitling, F., Broderick, J., Brüggen, M., Corstanje, A., Carbone, D., de Geus, E., de Vos, M., van Duin, A., Duscha, S., Eislöffel, J., Falcke, H., Fallows, R. A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., Gunst, A. W., Hamaker, J. P., Heald, G., Hoeft, M., Hörandel, J., Jütte, E., Kuper, G., Maat, P., Mann, G., Markoff, S., McFadden, R., McKay-Bukowski, D., McKean, J. P., Mulcahy, D. D., Munk, H., Nelles, A., Norden, M. J., Orrù, E., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pietka, G., Pizzo, R., Polatidis, A. G., Rafferty, D., Renting, A., Röttgering, H., Rowlinson, A., Scaife, A. M. M., Schwarz, D., Sluman, J., Smirnov, O., Steinmetz, M., Stewart, A., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Thoudam, Satyendra, Toribio, C., Vermeulen, R., Vocks, C., van Weeren, R. J., Wijers, R. A. M. J., Wise, M. W., Wucknitz, O., Yatawatta, S., and Zarka, P.

Abstract

PSR B0823+26, a 0.53-s radio pulsar, displays a host of emission phenomena over time-scales of seconds to (at least) hours, including nulling, subpulse drifting, and mode-changing. Studying pulsars like PSR B0823+26 provides further insight into the relationship between these various emission phenomena and what they might teach us about pulsar magnetospheres. Here we report on the LOFAR (Low-Frequency Array) discovery that PSR B0823+26 has a weak and sporadically emitting ‘quiet’ (Q) emission mode that is over 100 times weaker (on average) and has a nulling fraction forty-times greater than that of the more regularly-emitting ‘bright’ (B) mode. Previously, the pulsar has been undetected in the Q mode, and was assumed to be nulling continuously. PSR B0823+26 shows a further decrease in average flux just before the transition into the B mode, and perhaps truly turns off completely at these times. Furthermore, simultaneous observations taken with the LOFAR, Westerbork, Lovell, and Effelsberg telescopes between 110 MHz and 2.7 GHz demonstrate that the transition between the Q mode and B mode occurs within one single rotation of the neutron star, and that it is concurrent across the range of frequencies observed.

Published
2015
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2. Discovery of carbon radio recombination lines in absorption towards Cygnus A

Author

Oonk, J. B. R., van Weeren, R. J., Salgado, F., Morabito, L. K., Tielens, A. G. G. M., Rottgering, H. J. A., Asgekar, A., White, G. J., Alexov, A., Anderson, J., Avruch, I. M., Batejat, F., Beck, R., Bell, M. E., van Bemmel, I., Bentum, M. J., Bernardi, G., Best, P., Bonafede, A., Breitling, F., Brentjens, M., Broderick, J., Brüggen, M., Butcher, H. R., Ciardi, B., Conway, J. E., Corstanje, A., de Gasperin, F., de Geus, E., de Vos, M., Duscha, S., Eislöffel, J., Engels, D., van Enst, J., Falcke, H., Fallows, R. A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., Grießmeier, J., Hamaker, J. P., Hassall, T. E., Heald, G., Hessels, J. W. T., Hoeft, M., Horneffer, A., van der Horst, A., Iacobelli, M., Jackson, N. J., Juette, E., Karastergiou, A., Klijn, W., Kohler, J., Kondratiev, V. I., Kramer, M., Kuniyoshi, M., Kuper, G., van Leeuwen, J., Maat, P., Macario, G., Mann, G., Markoff, S., McKean, J. P., Mevius, M., Miller-Jones, J. C. A., Mol, J. D., Mulcahy, D. D., Munk, H., Norden, M. J., Orru, E., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pizzo, R., Polatidis, A. G., Reich, W., Scaife, A. M. M., Schoenmakers, A., Schwarz, D., Shulevski, A., Sluman, J., Smirnov, O., Sobey, C., Stappers, B. W., Steinmetz, M., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Veen, S. t., Thoudam, Satyendra, Toribio, C., van Nieuwpoort, R., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R. A. M. J., Wise, M. W., Wucknitz, O., Yatawatta, S., Zarka, P., Zensus, A., Oonk, J. B. R., van Weeren, R. J., Salgado, F., Morabito, L. K., Tielens, A. G. G. M., Rottgering, H. J. A., Asgekar, A., White, G. J., Alexov, A., Anderson, J., Avruch, I. M., Batejat, F., Beck, R., Bell, M. E., van Bemmel, I., Bentum, M. J., Bernardi, G., Best, P., Bonafede, A., Breitling, F., Brentjens, M., Broderick, J., Brüggen, M., Butcher, H. R., Ciardi, B., Conway, J. E., Corstanje, A., de Gasperin, F., de Geus, E., de Vos, M., Duscha, S., Eislöffel, J., Engels, D., van Enst, J., Falcke, H., Fallows, R. A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., Grießmeier, J., Hamaker, J. P., Hassall, T. E., Heald, G., Hessels, J. W. T., Hoeft, M., Horneffer, A., van der Horst, A., Iacobelli, M., Jackson, N. J., Juette, E., Karastergiou, A., Klijn, W., Kohler, J., Kondratiev, V. I., Kramer, M., Kuniyoshi, M., Kuper, G., van Leeuwen, J., Maat, P., Macario, G., Mann, G., Markoff, S., McKean, J. P., Mevius, M., Miller-Jones, J. C. A., Mol, J. D., Mulcahy, D. D., Munk, H., Norden, M. J., Orru, E., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pizzo, R., Polatidis, A. G., Reich, W., Scaife, A. M. M., Schoenmakers, A., Schwarz, D., Shulevski, A., Sluman, J., Smirnov, O., Sobey, C., Stappers, B. W., Steinmetz, M., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Veen, S. t., Thoudam, Satyendra, Toribio, C., van Nieuwpoort, R., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R. A. M. J., Wise, M. W., Wucknitz, O., Yatawatta, S., Zarka, P., and Zensus, A.

Abstract

We present the first detection of carbon radio recombination line absorption along the line of sight to Cygnus A. The observations were carried out with the Low Frequency Array in the 33–57 MHz range. These low-frequency radio observations provide us with a new line of sight to study the diffuse, neutral gas in our Galaxy. To our knowledge this is the first time that foreground Milky Way recombination line absorption has been observed against a bright extragalactic background source. By stacking 48 carbon α lines in the observed frequency range we detect carbon absorption with a signal-to-noise ratio of about 5. The average carbon absorption has a peak optical depth of 2 × 10−4, a line width of 10 km s−1 and a velocity of +4 km s−1 with respect to the local standard of rest. The associated gas is found to have an electron temperature Te ∼ 110 K and density ne ∼ 0.06 cm−3. These properties imply that the observed carbon α absorption likely arises in the cold neutral medium of the Orion arm of the Milky Way. Hydrogen and helium lines were not detected to a 3σ peak optical depth limit of 1.5 × 10−4 for a 4 km s−1 channel width. Radio recombination lines associated with Cygnus A itself were also searched for, but are not detected. We set a 3σ upper limit of 1.5 × 10−4 for the peak optical depth of these lines for a 4 km s−1 channel width.

Published
2014
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3. Lunar detection of ultra-high-energy cosmic rays and neutrinos with the square kilometre array

Author

Bray, J. D., Jaime Alvarez-Muniz, Buitink, S., Dagkesamanskii, R. D., Ekers, R. D., Falcke, H., Gayley, K. G., Huege, T., James, C. W., Mevius, M., Mute, R. L., Protheroe, R. J., Scholten, O., Spencer, R. E., and Veen, S. T.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract

The origin of the most energetic particles in nature, the ultra-high-energy (UHE) cosmic rays, is still a mystery. Only the most energetic of these have sufficiently small angular deflections to be used for directional studies, and their flux is so low that even the 3,000 km^2 Pierre Auger detector registers only about 30 cosmic rays per year of these energies. A method to provide an even larger aperture is to use the lunar Askaryan technique, in which ground-based radio telescopes search for the nanosecond radio flashes produced when a cosmic ray interacts with the Moon's surface. The technique is also sensitive to UHE neutrinos, which may be produced in the decays of topological defects from the early universe. Observations with existing radio telescopes have shown that this technique is technically feasible, and established the required procedure: the radio signal should be searched for pulses in real time, compensating for ionospheric dispersion and filtering out local radio interference, and candidate events stored for later analysis. For the Square Kilometre Array (SKA), this requires the formation of multiple tied-array beams, with high time resolution, covering the Moon, with either SKA1-LOW or SKA1-MID. With its large collecting area and broad bandwidth, the SKA will be able to detect the known flux of UHE cosmic rays using the visible lunar surface - millions of square km - as the detector, providing sufficient detections of these extremely rare particles to address the mystery of their origin., Contribution to the conference on "Advancing Astrophysics with the Square Kilometre Array" for the SKA science book; revised, accepted version

4. The LOFAR radio telescope as a Cosmic Ray detector

Author

Hörandel, J. R., Buitink, S., Corstanje, A., Emilio Enriquez, J., Falcke, H., Frieswijk, W., Krause, M., Nelles, A., Satyendra Thoudam, Schellart, P., Scholten, O., Veen, S. T. E. R., and Den Akker, M.

5. Measuring air showers with the LOFAR radio telescope

Author

Nelles, A., Buitink, S., Corstanje, A., Emilio Enriquez, J., Falcke, H., Frieswijk, W., Hörandel, J. R., Krause, M., Satyendra Thoudam, Schellart, P., Scholten, O., Veen, S. T. E. R., and Den Akker, M.

7. Discovery of carbon radio recombination lines in absorption towards Cygnus A

Author

Oonk, J. B. R., van Weeren, R. J., Salgado, F., Morabito, L. K., Tielens, A. G. G. M., Rottgering, H. J. A., Asgekar, A., White, G. J., Alexov, A., Anderson, J., Avruch, I. M., Batejat, F., Beck, R., Bell, M. E., van Bemmel, I., Bentum, M. J., Bernardi, G., Best, P., Bonafede, A., Breitling, F., Brentjens, M., Broderick, J., Bruggen, M., Butcher, H. R., Ciardi, B., Conway, J. E., Corstanje, A., de Gasperin, F., de Geus, E., de Vos, M., Duscha, S., Eisloffel, J., Engels, D., van Enst, J., Falcke, H., Fallows, R. A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., Griessmeier, J., Hamaker, J. P., Hassall, T. E., Heald, G., Hessels, J. W. T., Hoeft, M., Horneffer, A., Horst, A. v. d., Iacobelli, M., Jackson, N. J., Juette, E., Karastergiou, A., Klijn, W., Kohler, J., Kondratiev, V. I., Kramer, M., Kuniyoshi, M., Kuper, G., van Leeuwen, J., Maat, P., Macario, G., Mann, G., Markoff, S., McKean, J. P., Mevius, M., Miller-Jones, J. C. A., Mol, J. D., Mulcahy, D. D., Munk, H., Norden, M. J., Orru, E., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pizzo, R., Polatidis, A. G., Reich, W., Scaife, A. M. M., Schoenmakers, A., Schwarz, D., Shulevski, A., Sluman, J., Smirnov, O., Sobey, C., Stappers, B. W., Steinmetz, M., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Veen, S. t., Thoudam, S., Toribio, C., van Nieuwpoort, R., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R. A. M. J., Wise, M. W., Wucknitz, O., Yatawatta, S., Zarka, P., Zensus, A., Oonk, J. B. R., van Weeren, R. J., Salgado, F., Morabito, L. K., Tielens, A. G. G. M., Rottgering, H. J. A., Asgekar, A., White, G. J., Alexov, A., Anderson, J., Avruch, I. M., Batejat, F., Beck, R., Bell, M. E., van Bemmel, I., Bentum, M. J., Bernardi, G., Best, P., Bonafede, A., Breitling, F., Brentjens, M., Broderick, J., Bruggen, M., Butcher, H. R., Ciardi, B., Conway, J. E., Corstanje, A., de Gasperin, F., de Geus, E., de Vos, M., Duscha, S., Eisloffel, J., Engels, D., van Enst, J., Falcke, H., Fallows, R. A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., Griessmeier, J., Hamaker, J. P., Hassall, T. E., Heald, G., Hessels, J. W. T., Hoeft, M., Horneffer, A., Horst, A. v. d., Iacobelli, M., Jackson, N. J., Juette, E., Karastergiou, A., Klijn, W., Kohler, J., Kondratiev, V. I., Kramer, M., Kuniyoshi, M., Kuper, G., van Leeuwen, J., Maat, P., Macario, G., Mann, G., Markoff, S., McKean, J. P., Mevius, M., Miller-Jones, J. C. A., Mol, J. D., Mulcahy, D. D., Munk, H., Norden, M. J., Orru, E., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pizzo, R., Polatidis, A. G., Reich, W., Scaife, A. M. M., Schoenmakers, A., Schwarz, D., Shulevski, A., Sluman, J., Smirnov, O., Sobey, C., Stappers, B. W., Steinmetz, M., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Veen, S. t., Thoudam, S., Toribio, C., van Nieuwpoort, R., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R. A. M. J., Wise, M. W., Wucknitz, O., Yatawatta, S., Zarka, P., and Zensus, A.

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