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We determine the characteristics of the 7mm to 20cm wavelength radio variability in Sgr A* on time scales from days to three decades. The amplitude of the intensity modulation is between 30 and 39% at all wavelengths. Analysis of uniformly…

Astrophysics · Physics 2009-11-13 Jean-Pierre Macquart , Geoff Bower

Over the past decade it has become apparent that a class of `bursting pulsars' exist with the discovery of PSR J1752+2359 and PSR J1938+2213. In these pulsars, a sharp increase in the emission is observed that then tends to systematically…

Solar and Stellar Astrophysics · Physics 2014-02-10 Andrew Seymour , Duncan Lorimer , Josh Ridley

The 4.9 GHz Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey detected a drop in Interstellar Scintillation (ISS) for sources at redshifts z > 2, indicating an apparent increase in angular diameter or a decrease in flux…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-09 J. Y Koay , J. -P. Macquart , B. J. Rickett , H. E. Bignall , J. E. J. Lovell , C. Reynolds , D. L. Jauncey , T. Pursimo , L. Kedziora-Chudczer , R. Ojha

Radio waves are imprinted with propagation effects from ionized media through which they pass. Owing to electron density fluctuations, compact sources (pulsars, masers, and compact extragalactic sources) can display a wide variety of…

Astrophysics · Physics 2009-11-10 T. Joseph W. Lazio , J. M. Cordes , A. G. de Bruyn , J. -P. Macquart

An observer, situated several thousand light-years away from a radio pulsar, finds himself embedded in the diffraction pattern resulting from the propagation of the radio waves through the irregular interstellar medium. The observer's…

General Relativity and Quantum Cosmology · Physics 2010-11-01 Redouane Fakir

We present evidence of an extreme scattering event (ESE) toward PSR J2313+4253 using high-cadence observations taken with the Green Bank Observatory 20m telescope. The high density of observations in time allow for detailed tracking of the…

We apply a theory of wave propagation through a turbulent medium to the scattering of radio waves in pulsar magnetospheres. We find that under conditions of strong density modulation the effects of magnetospheric scintillations in…

Astrophysics · Physics 2009-10-31 Maxim Lyutikov , Anuj Parikh

I suggest that radio-wave scattering by the interstellar plasma, in combination with subsonic gradients in the Doppler velocity of interstellar HI, is responsible for the observed small-scale variation in HI absorption spectra of pulsars.…

Astrophysics · Physics 2009-11-06 C. R. Gwinn

A pulsar's scintillation bandwidth is inversely proportional to the scattering delay, making accurate measurements of scintillation bandwidth critical to characterize unmitigated delays in efforts to measure low-frequency gravitational…

Observation of Interplanetary Scintillation (IPS) provides an important and effective way to study the solar wind and the space weather. A series of IPS observations were conducted by the Five-hundred-meter Aperture Spherical radio…

Solar and Stellar Astrophysics · Physics 2022-08-03 Li-Jia Liu , Bo Peng , Lei Yu , Bin Liu , Ji-Guang Lu , Ye-Zhao Yu , Hong-Wei Xi , Ming Xiong , O. Chang

Visibility scintillation resulting from wave propagation through the turbulent ionosphere can be an important sources of noise at low radio frequencies ($\nu\lesssim 200$ MHz). Many low frequency experiments are underway to detect the power…

Instrumentation and Methods for Astrophysics · Physics 2016-03-16 H. K. Vedantham , L. V. E. Koopmans

We report radio observations of the quasar PMN J1106-3647. Our data, taken with the Australia Telescope Compact Array, show large variations in the amplitude and shape of its spectrum, on a short time-scale. A great variety of spectral…

High Energy Astrophysical Phenomena · Physics 2017-05-18 Artem V. Tuntsov , Jamie Stevens , Keith W. Bannister , Hayley Bignall , Simon Johnston , Cormac Reynolds , Mark A. Walker

Due to the inhomogeneity of electron number density, radio waves emitted by pulsars undergo scattering as they pass through the interstellar medium (ISM). However, a connection between large-scale pulsar scattering data and the structure of…

Astrophysics of Galaxies · Physics 2025-02-14 Qiuyi He , Xun Shi , Guangxing Li

We discovered rapid intra-day variability in radio source PMN J1726+0639 at GHz frequencies, during a survey to search for such variability with the Australia Telescope Compact Array. Follow-up observations were conducted over two years and…

Astrophysics of Galaxies · Physics 2022-04-27 Hayley E. Bignall , Artem V. Tuntsov , Jamie Stevens , Keith Bannister , Mark A. Walker , Cormac Reynolds

We present the results of the multi-frequency scatter time measurements for ten radio pulsars that were relatively less studied in this regard. The observations were performed using the Giant Meterwave Radio Telescope at the observing…

High Energy Astrophysical Phenomena · Physics 2015-10-21 Wojciech Lewandowski , Karolina Rozko , Jaroslaw Kijak , Bhaswati Bhattacharyya , Jayanta Roy

Interstellar radio wave scattering leads to flux density fluctuations and pulse broadening of pulsar signals. However, Galactic distribution and the structure of the scattering medium are still poorly understood. Pulsar pulse broadening…

Astrophysics of Galaxies · Physics 2023-12-19 Qiuyi He , Xun Shi

We use VLBA+VLA observations to measure the sizes of the scatter-broadened images of 6 of the most heavily scattered known pulsars: 3 within the Galactic Centre (GC) and 3 elsewhere in the inner Galactic plane. By combining the measured…

Astrophysics of Galaxies · Physics 2017-08-30 J. Dexter , A. Deller , G. C. Bower , P. Demorest , M. Kramer , B. W. Stappers , A. G. Lyne , M. Kerr , L. G. Spitler , D. Psaltis , M. Johnson , R. Narayan

We have searched 75 unidentified radio sources selected from the NRAO VLA Sky Survey (NVSS) catalog for the presence of rapidly spinning pulsars and short, dispersed radio bursts. The sources are radio bright, have no identifications or…

Solar and Stellar Astrophysics · Physics 2015-06-15 Deborah Schmidt , Fronefield Crawford , Glen Langston , Claire Gilpin

Pulsar radio emission undergoes dispersion due to the presence of free electrons in the interstellar medium (ISM). The dispersive delay in the arrival time of pulsar signal changes over time due to the varying ISM electron column density…

The aim of our work was to study the spatial structure of inhomogeneities of interstellar plasma in the directions of five pulsars: B0823+26, B0834+06, B1237+25, B1929+10, and B2016+28. Observations of these pulsars were made with…

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