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Variability of radio-emitting active galactic nuclei can be used to probe both intrinsic variations arising from shocks, flares, and other changes in emission from regions surrounding the central supermassive black hole, as well as…

High Energy Astrophysical Phenomena · Physics 2015-01-21 Hayley Bignall , Steve Croft , Talvikki Hovatta , Jun Yi Koay , Joseph Lazio , Jean-Pierre Macquart , Cormac Reynolds

We present the results of flux density monitoring of PSR B0329+54 at the frequency of 4.8 GHz using the 32-meter TCfA radiotelescope. The observations were conducted between 2002 and 2005. The main goal of the project was to find…

Astrophysics of Galaxies · Physics 2015-05-28 Wojciech Lewandowski , Jaroslaw Kijak , Yashwant Gupta , Krzysztof Krzeszowski

We propose that interstellar extreme scattering events, usually observed as pulsar scintillations, may be caused by a coherent agent rather than the usually assumed turbulence of $\rm H_2$ clouds. We find that the penetration of a flux of…

Astrophysics of Galaxies · Physics 2013-12-03 M. Angeles Perez-Garcia , Joseph Silk , Ue-Li Pen

The extreme, time-variable Faraday rotation observed in the repeating fast radio burst (FRB) 121102 and its associated persistent synchrotron source demonstrates that some FRBs originate in dense, dynamic and possibly relativistic…

High Energy Astrophysical Phenomena · Physics 2019-03-27 H. K. Vedantham , V. Ravi

The properties of interstellar matter (ISM) at the Sun are regulated by our location with respect to the Local Bubble (LB) void in the ISM. The LB is bounded by associations of massive stars and fossil supernovae that have disrupted natal…

Astrophysics · Physics 2009-11-13 P. C. Frisch

We report the discovery of VVV-WIT-04, a near-infrared variable source towards the Galactic disk located ~0.2 arcsec apart from the position of the radio source PMN J1515-5559. The object was found serendipitously in the near-IR data of the…

We study the impact of ionospheric disturbances on the Earth's environment caused by the solar events that occurred from 20 April to 31 May 2010, using observations from the Mexican Array Radio Telescope (MEXART). During this period of…

The INTEGRAL and Swift hard X-ray surveys have identified a large number of new sources, among which many are proposed as Cataclysmic Variables (CVs). Here we present the first detailed study of three X-ray selected CVs, Swift J1907.3-2050,…

We examine the relationship between astrometric stability and astrophysical properties in flat-spectrum radio-loud quasars making up the celestial reference frame. We use position determinations from geodetic VLBI measurements, and develop…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Robert Schaap , Stanislav Shabala , Simon Ellingsen , Oleg Titov , Jim Lovell

We present a theory for wave scintillation in the situation with a time-dependent partially coherent source and a time-dependent randomly heterogeneous medium. Our objective is to understand how the scintillation index of the measured…

Optics · Physics 2022-07-20 Josselin Garnier , Knut Solna

A few fast radio bursts' (FRBs) light-curves have exhibited large intrinsic modulations of their flux on extremely short ($t_{\rm r}\sim 10\mu$s) time scales, compared to pulse durations ($t_{\rm FRB}\sim1$ms). Light-curve variability…

High Energy Astrophysical Phenomena · Physics 2020-09-09 Paz Beniamini , Pawan Kumar

Young pulsars deviate from a perfectly regular spin-down by two non-deterministic phenomena: impulsive glitches and timing noise. Both phenomena are interesting per se, and may provide insights into the superfluid properties of neutron…

High Energy Astrophysical Phenomena · Physics 2023-02-17 Marco Antonelli , Avishek Basu , Brynmor Haskell

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

Hydrodynamic instabilities driven by a direct current are analyzed in 2D and 3D relativisticlike systems with the Dyakonov-Shur boundary conditions supplemented by a boundary condition for temperature. Besides the conventional Dyakonov-Shur…

Mesoscale and Nanoscale Physics · Physics 2021-10-25 P. O. Sukhachov , E. V. Gorbar , I. A. Shovkovy

We report the discovery of fast, frequency-dependent intensity variations from the scintillating intra-day variable quasar J1819+3845 at a wavelength of 21cm which resemble diffractive interstellar scintillations observed in pulsars. The…

Astrophysics · Physics 2009-11-11 Jean-Pierre Macquart , Ger de Bruyn

(abridged) The dust content of the universe is primarily explored via its interaction with stellar photons, producing interstellar extinction. However, owing to the physical extension of the observing beam, observations may detect scattered…

Solar and Stellar Astrophysics · Physics 2015-12-02 P. Scicluna , R. Siebenmorgen

Fractals are a basic tool to phenomenologically describe natural objects having a high degree of temporal or spatial variability. From a physical point of view the fractal properties of natural systems can also be interpreted by using the…

High Energy Astrophysical Phenomena · Physics 2015-05-28 C. S. Leung , J. Y. Wei , A. K. H. Kong , Z. Kovács , T. Harko

Effect of the induced Compton and Raman scattering on short, bright radio pulses is investigated. It is shown that when a single pulse propagates through the scattering medium, the effective optical depth is determined by the duration of…

Astrophysics · Physics 2009-11-13 Yuri Lyubarsky

Recent radio polarization observations have revealed a plethora of unexpected features in the polarized Galactic radio background that arise from propagation effects in the random (turbulent) interstellar medium. The canals are especially…

Astrophysics · Physics 2009-11-11 Andrew Fletcher , Anvar Shukurov

Remarkable progress has been made in understanding turbulent astrophysical plasmas in past decades including, notably, the solar wind and the interstellar medium. In the case of the solar wind, much of this progress has relied on in situ…

Solar and Stellar Astrophysics · Physics 2019-04-12 Tim Bastian , James Cordes , Justin Kasper , Adam Kobelski , Kelly Korreck , Gregory Howe , Steven Spangler , Chadi Salem , Angelos Vourlidas
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