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PKS 1257-326 is a quasar showing extremely unusual, rapid interstellar scintillation (ISS), which has persisted for at least a decade. Simultaneous observations with the VLA and ATCA, combined with ATCA monitoring over several years, have…

We report the discovery and timing of two pulsars from a sample of four circularly polarized sources identified in radio continuum images taken as part of the Australian SKA Pathfinder (ASKAP) Variables and Slow Transients (VAST) survey.…

High Energy Astrophysical Phenomena · Physics 2026-03-17 Rahul Sengar , David L. Kaplan , Emil Lenc , Akash Anumarlapudi , Natasha Hurley-Walker , Ziteng Wang , Laura Driessen , Dougal Dobie , Tara Murphy

We describe a data reduction pipeline for VLBI astrometric observations of pulsars, implemented using the ParselTongue AIPS interface. The pipeline performs calibration (including ionosphere modeling), phase referencing with proper…

Astrophysics · Physics 2008-12-18 A. T. Deller , S. J. Tingay , W. Brisken

The magnetized induced Compton scattering off the particles of the ultrarelativistic electron-positron plasma of pulsar is considered. The main attention is paid to the transverse regime of the scattering, which holds in a moderately strong…

Astrophysics · Physics 2009-11-13 S. A. Petrova

We report on 3.5 years of Chandra monitoring of the Galactic Centre magnetar SGR J1745-2900 since its outburst onset in April 2013. The magnetar spin-down has shown at least two episodes of period derivative increases so far, and it has…

SGR J1745$-$2900 is a magnetar near the Galactic center. X-ray observations of this source found a decreasing X-ray luminosity accompanied by an enhanced spindown rate. This negative correlation between X-ray luminosity and spindown rate is…

High Energy Astrophysical Phenomena · Physics 2015-09-16 H. Tong

We describe the results of a mJy-sensitivity, VLA survey of roughly 1 square degree near the Galactic center at 6 and 20 cm. Catalogs of compact and filamentary structures are given and compared to previous surveys of the region. Eight of…

Astrophysics · Physics 2009-11-13 C. J. Law , F. Yusef-Zadeh , W. D. Cotton

The RadioAstron space radio telescope provides a unique opportunity to study the extreme brightness temperatures ($\mathrm{T_B }$) in AGNs with unprecedented long baselines of up to 28 Earth diameters. Since interstellar scintillation (ISS)…

Context. Interstellar scintillation (ISS) of pulsar emission can be used both as a probe of the ionised interstellar medium (IISM) and cause corruptions in pulsar timing experiments. Of particular interest are so-called scintillation arcs…

It was recently suggested by Boldyrev & Gwinn that the characteristics of radio scintillations from distant pulsars are best understood if the interstellar electron-density fluctuations that cause the time broadening of the radio pulses…

Astrophysics · Physics 2010-11-11 Stanislav Boldyrev , Arieh Konigl

We have used the Green Bank Telescope to observe the millisecond pulsar PSR J0514-4002A on 43 occasions spread over 2 years. This 5-ms pulsar is located in the globular cluster NGC 1851; it belongs to a binary system and has a highly…

Astrophysics · Physics 2011-02-11 Paulo C. Freire , Scott M. Ransom , Yashwant Gupta

The Parkes multibeam pulsar survey is a sensitive survey of a strip along the Galactic plane with |b|<5 deg and l=260 deg to l=50 deg. It uses a 13-beam receiver on the 64-m Parkes radio telescope, receiving two polarisations per beam over…

Extreme Scattering Events and pulsar secondary spectra have highlighted fundamental problems in our understanding of the dynamics of interstellar turbulence. We describe some of these problems in detail and present the theory behind the…

Astrophysics of Galaxies · Physics 2015-06-11 Jean-Pierre Macquart

The Parkes 20 cm Multibeam pulsar surveys have discovered nearly half of the known pulsars and revealed many distant pulsars with high dispersion measures. Using a sample of 1,301 pulsars from these surveys, we have explored the spatial…

High Energy Astrophysical Phenomena · Physics 2024-02-23 J. T. Xie , J. B. Wang , N. Wang , R. Manchester , G. Hobbs

The magnetar SGR J1745-2900 located in the vicinity of the supermassive black hole Sgr A$^{\star}$ was detected during its X-ray outburst with the Swifht/XRT telescope in April 2013. For several months after its detection the source was…

High Energy Astrophysical Phenomena · Physics 2021-06-10 E. A. Kuznetsova , A. A. Lutovinov , A. N. Semena

Short time-scale flux density variations of flat spectrum radio sources are often explained by the scattering of radio waves in the turbulent, ionized Interstellar Matter of the Milky Way. One of the most convincing observational arguments…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-26 K. E. Gabanyi , N. Marchili , T. P. Krichbaum , L. Fuhrmann , P. Muller , J. A. Zensus , X. Liu , H. G. Song

Previous VLBI observations of the lens system CLASS B0128+437 showed that the lensed source had a triple sub-component structure. However, one of the images looked very different to the others and it has been suggested that this is due to…

Astrophysics · Physics 2007-05-23 A. D. Biggs

We report on multi-frequency, wideband radio observations of the Galactic Center magnetar (SGR 1745$-$2900) with the Green Bank Telescope for $\sim$100 days immediately following its initial X-ray outburst in April 2013. We made multiple…

High Energy Astrophysical Phenomena · Physics 2015-08-06 T. T. Pennucci , A. Possenti , P. Esposito , N. Rea , D. Haggard , F. K. Baganoff , M. Burgay , F. Coti Zelati , G. L. Israel , A. Minter

Gravitational scattering events, in which the path of an interstellar object is deflected by a pulsar or the solar system, give rise to reflex motion which can potentially be detected using pulsar timing. We determine the form of the timing…

High Energy Astrophysical Phenomena · Physics 2020-02-12 Ross J. Jennings , James M. Cordes , Shami Chatterjee

Density fluctuations in the ionised interstellar medium have a profound effect on radio pulsar observations, through angular scattering, intensity scintillations, and small changes in time delays from dispersion. Here we show that it is…

High Energy Astrophysical Phenomena · Physics 2023-04-12 Daniel J. Reardon , William A. Coles