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The University of Tasmania Ceduna radio telescope has been used to investigate rapid variability in the radio flux density of the BL Lac object PKS B1144-379 at 6.7 GHz. High-cadence monitoring of this extreme scintillator was carried out…

Astrophysics of Galaxies · Physics 2020-09-03 N. M. M. Said , S. P. Ellingsen , H. E. Bignall , S. Shabala , J. N. McCallum , C. Reynolds

Our analysis of archival VLBI data of PSR 0834+06 revealed that its scintillation properties can be precisely modelled using the inclined sheet model (Pen & Levin 2014), resulting in two distinct lens planes. These data strongly favour the…

Solar and Stellar Astrophysics · Physics 2016-02-17 Siqi Liu , Ue-Li Pen , J-P Macquart , Walter Brisken , Adam Deller

The nature of irregularly spaced pulses of rotating radio transients (RRATs) complicates interstellar scintillation studies. In this letter, we report the primary scintillation parameters of a sample of RRATs using pairwise correlations of…

Refractive interstellar scintillation (RISS) is thought to be the cause behind a variety of phenomena seen at radio wavelengths in pulsars and compact radio sources. Though there is substantial observational data to support several…

Astrophysics · Physics 2009-10-31 N. D. Ramesh Bhat , A. Pramesh Rao , Yashwant Gupta

We present observations of high-amplitude rapid (2 s) variability toward two bright, compact extragalactic radio sources out of several hundred of the brightest radio sources in one of the 30x30 deg MWA Epoch of Reionization fields using…

The propagation of radio waves from distant compact radio sources through turbulent interstellar plasma in our Galaxy causes these sources to twinkle, a phenomenon called interstellar scintillation. Such scintillations are a unique probe of…

We report on an effort to extract and monitor interstellar scintillation parameters in regular timing observations collected for the NANOGrav pulsar timing array. Scattering delays are measured by creating dynamic spectra for each pulsar…

Radio pulsars scintillate because their emission travels through the ionized interstellar medium via multiple paths, which interfere with each other. It has long been realized that the scattering screens responsible for the scintillation…

High Energy Astrophysical Phenomena · Physics 2018-05-25 Robert Main , I-Sheng Yang , Victor Chan , Dongzi Li , Fang Xi Lin , Nikhil Mahajan , Ue-Li Pen , Keith Vanderlinde , Marten H. van Kerkwijk

Turbulence in the Local Bubble could play an important role in the thermodynamics of the gas that is there. The best astronomical technique for measuring turbulence in astrophysical plasmas is radio scintillation. Measurements of the level…

Astrophysics · Physics 2009-06-23 Steven R. Spangler

The emission geometries, e.g. the emission region height, the beam shape, and radius-to-frequency mapping, are important predictions of pulsar radiation model. The multi-band radio observations carry such valuable information. In this…

High Energy Astrophysical Phenomena · Physics 2017-05-31 L. H. Shang , J. G. Lu , Y. J. Du , L. F. Hao , D. Li , K. J. Lee , Bin Li , L. X. Li , G. J. Qiao , Z. Q. Shen , D. H. Wang , M. Wang , X. J. Wu , Y. J. Wu , R. X. Xu , Y. L. Yue , Z. Yan , Q. J. Zhi , R. B. Zhao , R. S. Zhao

We present the first measurement of pulse scattering close to the eclipse region of PSR B1957+20, which is in a compact binary system with a low-mass star. We measured pulse scattering time-scales up to 0.2 ms close to the eclipse and…

High Energy Astrophysical Phenomena · Physics 2022-04-20 J. T. Bai , S. Dai , Q. J. Zhi , W. A. Coles , D. Li , W. W. Zhu , G. Hobbs , G. J. Qiao , N. Wang , J. P. Yuan , M. D. Filipovic , J. B. Wang , Z. C. Pan , L. H. Shang , S. J. Dang , S. Q. Wang , C. C. Miao

Radio pulsars, as highly coherent point sources, serve as powerful probes of the ionized interstellar medium (IISM). Pulsar scintillation observations have revealed inverted arclets on the secondary spectrum, indicating quasilinearly…

Astrophysics of Galaxies · Physics 2026-04-14 Zhu Xu , Xun Shi

The rare and conspicuous flux density variations of some radio sources (extragalactic and pulsars) for periods of weeks to months have been denoted Extreme Scattering Events (ESE's) by Fiedler et al. (1987). Presently, there is no…

Astrophysics · Physics 2009-11-13 Murad Hamidouche , Jean-Francois Lestrade

Ground-based observation of Interplanetary Scintillation(IPS) is an important approach of monitoring solar wind. A ground-based IPS observation system is newly implemented on 50m radio telescope, Miyun station, National Astronomical…

Instrumentation and Methods for Astrophysics · Physics 2015-06-04 Xin-Ying Zhu , Xi-Zhen Zhang , Hong-Bo Zhang , De-Qing Kong , Hui-Peng Qu

We propose to use pulsar scintillation measurements to test predictions of alternative theories of gravity. Comparing to single-path pulsar timing measurements, the scintillation measurements can achieve a factor of 10^5 improvement in…

General Relativity and Quantum Cosmology · Physics 2017-05-03 Huan Yang , Atsushi Nishizawa , Ue-Li Pen

Refractive scintillation effects are powerful techniques for discriminating between different models proposed for the electron density fluctuation spectrum in the ISM. Data from our long-term scintillation study of 18 pulsars in the DM…

Astrophysics · Physics 2009-10-31 N. D. Ramesh Bhat , Yashwant Gupta , A. Pramesh Rao

Refractive Interstellar Scintillation (RISS) effects on pulsar signals are powerful techniques for discriminating between different models that have been proposed for the power spectrum of plasma density fluctuations in the Interstellar…

Astrophysics · Physics 2007-05-23 N. D. Ramesh Bhat , Yashwant Gupta , A. Pramesh Rao

We present the measurements of scatter broadening time-scales ($\tau_{sc}$) for 124 pulsars at 327 MHz, using the upgraded Ooty Radio Telescope (ORT). These pulsars lie in the dispersion measure range of 37 $-$ 503 pc cm$^{-3}$ and…

High Energy Astrophysical Phenomena · Physics 2017-06-20 M. A. Krishnakumar , Dipanjan Mitra , Arun Naidu , Bhal Chandra Joshi , P. K. Manoharan

The remarkable rapid variations in radio flux density and polarization of the quasar PKS 0405-385 observed in 1996 are subject to a correlation analysis, from which characteristic time scales and amplitudes are derived. The variations are…

Astrophysics · Physics 2009-11-07 Barney J. Rickett , Lucyna Kedziora-Chudczer , David L. Jauncey

We have examined data from pulsars B0950+08 and B0329+54 for evidence of temporally coherent radiation using the modified coherence function (MCF) technique of Jenet et al. (2001). We consider the influence of both instrumental bandpass and…

Astrophysics · Physics 2009-11-07 J. M. Smits , B. W. Stappers , J-P. Macquart , R. Ramachandran , J. Kuijpers
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