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10 results on '"Karuppusamy R"'

1. PSR B0329+54: STATISTICS OF SUBSTRUCTURE DISCOVERED WITHIN THE SCATTERING DISK ON RADIOASTRON BASELINES OF UP TO 235,000 km

Author

Gwinn, CR, Popov, MV, Bartel, N, Andrianov, AS, Johnson, MD, Joshi, BC, Kardashev, NS, Karuppusamy, R, Kovalev, YY, Kramer, M, Rudnitskii, AG, Safutdinov, ER, Shishov, VI, Smirnova, TV, Soglasnov, VA, Steinmassl, SF, Zensus, JA, and Zhuravlev, VI

Subjects
pulsars: individual, radio continuum: ISM, scattering, techniques: high angular resolution, astro-ph.GA, astro-ph.IM, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract

We discovered fine-scale structure within the scattering disk of PSR B0329+54in observations with the RadioAstron ground-space radio interferometer. Here,we describe this phenomenon, characterize it with averages and correlationfunctions, and interpret it as the result of decorrelation of theimpulse-response function of interstellar scattering between thewidely-separated antennas. This instrument included the 10-m Space RadioTelescope, the 110-m Green Bank Telescope, the 14x25-m Westerbork SynthesisRadio Telescope, and the 64-m Kalyazin Radio Telescope. The observations wereperformed at 324 MHz, on baselines of up to 235,000 km in November 2012 andJanuary 2014. In the delay domain, on long baselines the interferometricvisibility consists of many discrete spikes within a limited range of delays.On short baselines it consists of a sharp spike surrounded by lower spikes. Theaverage envelope of correlations of the visibility function show twoexponential scales, with characteristic delays of $\tau_1=4.1\pm 0.3\ \mu{\rms}$ and $\tau_2=23\pm 3\ \mu{\rm s}$, indicating the presence of two scales ofscattering in the interstellar medium. These two scales are present in thepulse-broadening function. The longer scale contains 0.38 times the scatteredpower of the shorter one. We suggest that the longer tail arises fromhighly-scattered paths, possibly from anisotropic scattering or fromsubstructure at large angles.

Published
2016

2. RADIOASTRON STUDIES OF THE NEARBY, TURBULENT INTERSTELLAR PLASMA WITH THE LONGEST SPACE–GROUND INTERFEROMETER BASELINE

Author

Smirnova, TV, Shishov, VI, Popov, MV, Gwinn, CR, Anderson, JM, Andrianov, AS, Bartel, N, Deller, A, Johnson, MD, Joshi, BC, Kardashev, NS, Karuppusamy, R, Kovalev, YY, Kramer, M, Soglasnov, VA, Zensus, JA, and Zhuravlev, VI

Subjects
ISM: structure, pulsars: general, pulsars: individual, astro-ph.GA, astro-ph.IM, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract

RadioAstron space-ground very long baseline interferometry observations of the pulsar B0950+08, conducted with the 10 m Space Radio Telescope in conjunction with the Arecibo 300 m telescope and the Westerbork Synthesis Radio Telescope at a frequency of 324 MHz were analyzed in order to investigate plasma inhomogeneities in the direction of this nearby pulsar. The observations were conducted at a spacecraft distance of 330, 000 km, resulting in a projected baseline of 220, 000 km, providing the greatest angular resolution ever achieved at meter wavelengths. Our analysis is based on fundamental behavior of structure and coherence functions. We find that the pulsar shows scintillation on two frequency scales, both much less than the observing frequency, but modulation is less than 100%. We infer that the scattering is weak, but a refracting wedge disperses the scintillation pattern. The refraction angle of this "cosmic prism" is measured as θ0 = 1.1-4.4 mas, with the refraction direction being approximately perpendicular to the observer velocity. We show that the observed parameters of scintillation effects indicate that two plasma layers lie along the line of sight to the pulsar, at distances of 4.4-16.4 pc and 26-170 pc, and traveling in different directions relative to the line of sight. Spectra of turbulence for the two layers are found to follow a power law with the indices γ1 = γ2 = 3.00 ± 0.08, significantly different from the index expected for a Kolmogorov spectrum of turbulence, γ = 11/3.

Published
2014

3. Simultaneous X-Ray and Radio Observations of the Repeating Fast Radio Burst FRB ∼ 180916.J0158+65

Author

Scholz, P., primary, Cook, A., additional, Cruces, M., additional, Hessels, J. W. T., additional, Kaspi, V. M., additional, Majid, W. A., additional, Naidu, A., additional, Pearlman, A. B., additional, Spitler, L. G., additional, Bandura, K. M., additional, Bhardwaj, M., additional, Cassanelli, T., additional, Chawla, P., additional, Gaensler, B. M., additional, Good, D. C., additional, Josephy, A., additional, Karuppusamy, R., additional, Keimpema, A., additional, Kirichenko, A. Yu., additional, Kirsten, F., additional, Kocz, J., additional, Leung, C., additional, Marcote, B., additional, Masui, K., additional, Mena-Parra, J., additional, Merryfield, M., additional, Michilli, D., additional, Naudet, C. J., additional, Nimmo, K., additional, Pleunis, Z., additional, Prince, T. A., additional, Rafiei-Ravandi, M., additional, Rahman, M., additional, Shin, K., additional, Smith, K. M., additional, Stairs, I. H., additional, Tendulkar, S. P., additional, and Vanderlinde, K., additional

Published
2020
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5. Revival of the Magnetar PSR J1622–4950: Observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

Author

Camilo, F., primary, Scholz, P., additional, Serylak, M., additional, Buchner, S., additional, Merryfield, M., additional, Kaspi, V. M., additional, Archibald, R. F., additional, Bailes, M., additional, Jameson, A., additional, Straten, W. van, additional, Sarkissian, J., additional, Reynolds, J. E., additional, Johnston, S., additional, Hobbs, G., additional, Abbott, T. D., additional, Adam, R. M., additional, Adams, G. B., additional, Alberts, T., additional, Andreas, R., additional, Asad, K. M. B., additional, Baker, D. E., additional, Baloyi, T., additional, Bauermeister, E. F., additional, Baxana, T., additional, Bennett, T. G. H., additional, Bernardi, G., additional, Booisen, D., additional, Booth, R. S., additional, Botha, D. H., additional, Boyana, L., additional, Brederode, L. R. S., additional, Burger, J. P., additional, Cheetham, T., additional, Conradie, J., additional, Conradie, J. P., additional, Davidson, D. B., additional, Bruin, G. De, additional, Swardt, B. de, additional, Villiers, C. de, additional, Villiers, D. I. L. de, additional, Villiers, M. S. de, additional, Villiers, W. de, additional, Waal, C. De, additional, Dikgale, M. A., additional, Toit, G. du, additional, Toit, L. J. du, additional, Esterhuyse, S. W. P., additional, Fanaroff, B., additional, Fataar, S., additional, Foley, A. R., additional, Foster, G., additional, Fourie, D., additional, Gamatham, R., additional, Gatsi, T., additional, Geschke, R., additional, Goedhart, S., additional, Grobler, T. L., additional, Gumede, S. C., additional, Hlakola, M. J., additional, Hokwana, A., additional, Hoorn, D. H., additional, Horn, D., additional, Horrell, J., additional, Hugo, B., additional, Isaacson, A., additional, Jacobs, O., additional, van Rensburg, J. P. Jansen, additional, Jonas, J. L., additional, Jordaan, B., additional, Joubert, A., additional, Joubert, F., additional, Józsa, G. I. G., additional, Julie, R., additional, Julius, C. C., additional, Kapp, F., additional, Karastergiou, A., additional, Karels, F., additional, Kariseb, M., additional, Karuppusamy, R., additional, Kasper, V., additional, Knox-Davies, E. C., additional, Koch, D., additional, Kotzé, P. P. A., additional, Krebs, A., additional, Kriek, N., additional, Kriel, H., additional, Kusel, T., additional, Lamoor, S., additional, Lehmensiek, R., additional, Liebenberg, D., additional, Liebenberg, I., additional, Lord, R. T., additional, Lunsky, B., additional, Mabombo, N., additional, Macdonald, T., additional, Macfarlane, P., additional, Madisa, K., additional, Mafhungo, L., additional, Magnus, L. G., additional, Magozore, C., additional, Mahgoub, O., additional, Main, J. P. L., additional, Makhathini, S., additional, Malan, J. A., additional, Malgas, P., additional, Manley, J. R., additional, Manzini, M., additional, Marais, L., additional, Marais, N., additional, Marais, S. J., additional, Maree, M., additional, Martens, A., additional, Matshawule, S. D., additional, Matthysen, N., additional, Mauch, T., additional, Nally, L. D. Mc, additional, Merry, B., additional, Millenaar, R. P., additional, Mjikelo, C., additional, Mkhabela, N., additional, Mnyandu, N., additional, Moeng, I. T., additional, Mokone, O. J., additional, Monama, T. E., additional, Montshiwa, K., additional, Moss, V., additional, Mphego, M., additional, New, W., additional, Ngcebetsha, B., additional, Ngoasheng, K., additional, Niehaus, H., additional, Ntuli, P., additional, Nzama, A., additional, Obies, F., additional, Obrocka, M., additional, Ockards, M. T., additional, Olyn, C., additional, Oozeer, N., additional, Otto, A. J., additional, Padayachee, Y., additional, Passmoor, S., additional, Patel, A. A., additional, Paula, S., additional, Peens-Hough, A., additional, Pholoholo, B., additional, Prozesky, P., additional, Rakoma, S., additional, Ramaila, A. J. T., additional, Rammala, I., additional, Ramudzuli, Z. R., additional, Rasivhaga, M., additional, Ratcliffe, S., additional, Reader, H. C., additional, Renil, R., additional, Richter, L., additional, Robyntjies, A., additional, Rosekrans, D., additional, Rust, A., additional, Salie, S., additional, Sambu, N., additional, Schollar, C. T. G., additional, Schwardt, L., additional, Seranyane, S., additional, Sethosa, G., additional, Sharpe, C., additional, Siebrits, R., additional, Sirothia, S. K., additional, Slabber, M. J., additional, Smirnov, O., additional, Smith, S., additional, Sofeya, L., additional, Songqumase, N., additional, Spann, R., additional, Stappers, B., additional, Steyn, D., additional, Steyn, T. J., additional, Strong, R., additional, Struthers, A., additional, Stuart, C., additional, Sunnylall, P., additional, Swart, P. S., additional, Taljaard, B., additional, Tasse, C., additional, Taylor, G., additional, Theron, I. P., additional, Thondikulam, V., additional, Thorat, K., additional, Tiplady, A., additional, Toruvanda, O., additional, Aardt, J. van, additional, Balla, T. van, additional, Heever, L. van den, additional, Byl, A. van der, additional, Merwe, C. van der, additional, Merwe, P. van der, additional, Niekerk, P. C. van, additional, Rooyen, R. van, additional, Staden, J. P. van, additional, Tonder, V. van, additional, Wyk, R. van, additional, Wait, I., additional, Walker, A. L., additional, Wallace, B., additional, Welz, M., additional, Williams, L. P., additional, Xaia, B., additional, Young, N., additional, and Zitha, S., additional

Published
2018
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6. Large Magneto-ionic Variations toward the Galactic Center Magnetar, PSR J1745-2900

Author

Desvignes, G., primary, Eatough, R. P., additional, Pen, U. L., additional, Lee, K. J., additional, Mao, S. A., additional, Karuppusamy, R., additional, Schnitzeler, D. H. F. M., additional, Falcke, H., additional, Kramer, M., additional, Wucknitz, O., additional, Spitler, L. G., additional, Torne, P., additional, Liu, K., additional, Bower, G. C., additional, Cognard, I., additional, Lyne, A. G., additional, and Stappers, B. W., additional

Published
2018
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7. A 24 HR GLOBAL CAMPAIGN TO ASSESS PRECISION TIMING OF THE MILLISECOND PULSAR J1713+0747

Author

Dolch, T., primary, Lam, M. T., additional, Cordes, J., additional, Chatterjee, S., additional, Bassa, C., additional, Bhattacharyya, B., additional, Champion, D. J., additional, Cognard, I., additional, Crowter, K., additional, Demorest, P. B., additional, Hessels, J. W. T., additional, Janssen, G., additional, Jenet, F. A., additional, Jones, G., additional, Jordan, C., additional, Karuppusamy, R., additional, Keith, M., additional, Kondratiev, V., additional, Kramer, M., additional, Lazarus, P., additional, Lazio, T. J. W., additional, Lee, K. J., additional, McLaughlin, M. A., additional, Roy, J., additional, Shannon, R. M., additional, Stairs, I., additional, Stovall, K., additional, Verbiest, J. P. W., additional, Madison, D. R., additional, Palliyaguru, N., additional, Perrodin, D., additional, Ransom, S., additional, Stappers, B., additional, Zhu, W. W., additional, Dai, S., additional, Desvignes, G., additional, Guillemot, L., additional, Liu, K., additional, Lyne, A., additional, Perera, B. B. P., additional, Petroff, E., additional, Rankin, J. M., additional, and Smits, R., additional

Published
2014
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8. RADIOASTRONSTUDIES OF THE NEARBY, TURBULENT INTERSTELLAR PLASMA WITH THE LONGEST SPACE-GROUND INTERFEROMETER BASELINE

Author

Smirnova, T. V., primary, Shishov, V. I., additional, Popov, M. V., additional, Gwinn, C. R., additional, Anderson, J. M., additional, Andrianov, A. S., additional, Bartel, N., additional, Deller, A., additional, Johnson, M. D., additional, Joshi, B. C., additional, Kardashev, N. S., additional, Karuppusamy, R., additional, Kovalev, Y. Y., additional, Kramer, M., additional, Soglasnov, V. A., additional, Zensus, J. A., additional, and Zhuravlev, V. I., additional

Published
2014
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9. PULSE BROADENING MEASUREMENTS FROM THE GALACTIC CENTER PULSAR J1745-2900

Author

Spitler, L. G., primary, Lee, K. J., additional, Eatough, R. P., additional, Kramer, M., additional, Karuppusamy, R., additional, Bassa, C. G., additional, Cognard, I., additional, Desvignes, G., additional, Lyne, A. G., additional, Stappers, B. W., additional, Bower, G. C., additional, Cordes, J. M., additional, Champion, D. J., additional, and Falcke, H., additional

Published
2013
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10. EINSTEIN@HOME DISCOVERY OF FOUR YOUNG GAMMA-RAY PULSARS IN FERMI LAT DATA

Author

Pletsch, H. J., primary, Guillemot, L., additional, Allen, B., additional, Anderson, D., additional, Aulbert, C., additional, Bock, O., additional, Champion, D. J., additional, Eggenstein, H. B., additional, Fehrmann, H., additional, Hammer, D., additional, Karuppusamy, R., additional, Keith, M., additional, Kramer, M., additional, Machenschalk, B., additional, Ng, C., additional, Papa, M. A., additional, Ray, P. S., additional, and Siemens, X., additional

Published
2013
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