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We study three quasar radio sources (B1257-326, B1519-273, and J1819+385) that show large amplitude intraday and annual scintillation variability produced by the Earth's motion relative to turbulent-scattering screens located within a few…

Astrophysics · Physics 2009-11-13 Jeffrey L. Linsky , Barney J. Rickett , Seth Redfield

We present here a method to study the distribution of electron density fluctuations in pulsar directions as well as to estimate pulsar distances. The method, based on a simple two-component model of the scattering medium discussed by Gwinn…

Astrophysics · Physics 2009-10-30 A. A. Deshpande , R. Ramachandran

We report two phenomena detected in PSR J0344$-$0901 from two observations conducted at frequency centered at 1.25 GHz using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The first phenomenon manifests as shifting in the…

High Energy Astrophysical Phenomena · Physics 2024-02-26 H. M. Tedila , R. Yuen , N. Wang , D. Li , Z. G. Wen , W. M. Yan , J. P. Yuan , X. H. Han , P. Wang , W. W. Zhu , S. J. Dang , S. Q. Wang , J. T. Xie , Q. D. Wu , Sh. Khasanov , FAST Collaboration

Analysis of ten years of high-precision timing data on the millisecond pulsar PSR J0437-4715 has resulted in a model-independent kinematic distance based on an apparent orbital period derivative, Pbdot, determined at the 1.5% level of…

We measure the proper motion of the pulsar PSR J1745-2900 relative to the Galactic Center massive black hole, Sgr A*, using the Very Long Baseline Array (VLBA). The pulsar has a transverse velocity of 236 +/- 11 km s^-1 at position angle 22…

The diverse polarization properties in pulsars are in conflict with applying a unique emission mechanism to the population. The polarization position angle (PPA) traverse in most pulsars shows a S-shaped curve that can be interpreted using…

High Energy Astrophysical Phenomena · Physics 2023-03-01 Dipanjan Mitra , George I. Melikidze , Rahul Basu

Radio pulsar signals are significantly perturbed by their propagation through the ionized interstellar medium. In addition to the frequency-dependent pulse times of arrival due to dispersion, pulse shapes are also distorted and shifted,…

Quasars shine brightly due to the liberation of gravitational energy as matter falls onto a supermassive black hole in the centre of a galaxy. Variations in the radiation received from active galactic nuclei (AGN) are studied at all…

Astrophysics · Physics 2015-06-24 J. Dennett-Thorpe , A. G. de Bruyn

The Crab pulsar has striking radio emission properties, with the two dominant pulse components -- the main pulse and the interpulse -- consisting entirely of giant pulses. The emission is scattered in both the Crab nebula and the…

Neutron stars in close binary systems have the potential to spin up to millisecond periods due to the accretion of matter and angular momentum from their low-mass companions. In later stages of this process, they sometimes start to swing…

High Energy Astrophysical Phenomena · Physics 2026-05-22 S. V. Karpov , Artyom S. Tanashkin , G. M. Beskin , V. L. Plokhotnichenko , Y. A. Shibanov , D. A. Zyuzin

The pulsed radio emission from the Galactic Center (GC) magnetar SGR J1745-29 probes the turbulent, magnetized plasma of the GC hyperstrong scattering screen through both angular and temporal broadening. We present the first measurements of…

We present the results from an Australian Square Kilometre Array Pathfinder search for radio variables on timescales of hours. We conducted an untargeted search over a 30 deg$^2$ field, with multiple 10-hour observations separated by days…

Fast radio bursts (FRBs) are millisecond-timescale radio transients, the origins of which are predominantly extragalactic and likely involve highly magnetized compact objects. FRBs undergo multipath propagation, or scattering, from electron…

High Energy Astrophysical Phenomena · Physics 2022-12-14 S. K. Ocker , J. M. Cordes , S. Chatterjee , D. Li , C. H. Niu , J. W. McKee , C. J. Law , R. Anna-Thomas

We have carried out a detailed study of individual pulse emission from the pulsar J1741$-$0840 (B1738$-$08), observed using the Parkes and Effelsberg radio telescopes at the $L$ band. The pulsar exhibits four emission components which are…

High Energy Astrophysical Phenomena · Physics 2024-10-01 Yonghua Xu , Zhigang Wen , Jianping Yuan , Zhen Wang , Xuefeng Duan , Zhen Wang , Na Wang , Min Wang , Hongguang Wang , Abdujappar Rusul , Longfei Hao , Wei Han

A new method for separating intensity variations of a source's radio emission having various physical natures is proposed. The method is based on a joint analysis of the structure function of the intensity variations and the asymmetry…

Astrophysics · Physics 2009-11-11 V. I. Shishov , T. V. Smirnova

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

Observations over the last two decades have shown that a significant fraction of all flat-spectrum, extragalactic radio sources exhibit flux density variations on timescales of a day or less at frequencies of several GHz. It has been…

A subset of magnetic stars exhibit periodic radio pulses produced by the coherent electron cyclotron maser mechanism. These pulses are known to exhibit both temporal and spectral variations, which have been attributed to phenomena intrinsic…

Solar and Stellar Astrophysics · Physics 2026-04-21 J. S. Morgan , B. Das , H. E. Bignall

Rotating Radio Transients (RRATs) represent a relatively new class of pulsar, primarily characterised by their sporadic bursting emission of single pulses on time scales of minutes to hours. In addition to the difficulty involved in…

High Energy Astrophysical Phenomena · Physics 2019-09-11 B. W. Meyers , S. E. Tremblay , N. D. R. Bhat , R. M. Shannon , S. M. Ord , C. Sobey , M. Johnston-Hollitt , M. Walker , R. B. Wayth

The observed interstellar scintillation pattern of an intra-day variable radio source is influenced by its source structure. If the velocity of the interstellar medium responsible for the scattering is comparable to the earth's, the vector…

Astrophysics · Physics 2009-11-07 J-P Macquart , D. L. Jauncey