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Signals from radio pulsars show a wavelength-dependent delay due to dispersion in the interstellar plasma. At a typical observing wavelength, this delay can vary by tens of microseconds on five-year time scales, far in excess of signals of…

We have detected a strong deflection of radio waves from the pulsar PSR B0834+06 in scintillation observations. Interference between the undeflected pulsar image and deflected subimages allows single dish interferometry of the interstellar…

Pulsars with periods more than 0.4 seconds in the declination range -9o < decj < 42o and in the right ascension range 0h < r.a.< 24h were searched in parallel with the program of interplanetary scintillations monitoring of a large number of…

Traditional pulsar surveys have primarily employed time-domain periodicity searches. However, these methods are susceptible to effects like scattering, eclipses and orbital motion. At lower radio frequencies (<= 300 MHz), factors such as…

High Energy Astrophysical Phenomena · Physics 2024-11-20 S. Sett , M. Sokolowski , E. Lenc , N. D. R. Bhat

We use cyclic spectroscopy to directly measure the scintillation parameter $C_1$ for the millisecond pulsar B1937+21. This marks the first time this constant has been measured for any pulsar without assuming a pulse broadening function…

High Energy Astrophysical Phenomena · Physics 2026-05-27 Jacob E. Turner

Pulsar scintillation can be used to measure small scale structure in the Galaxy, but little is known about the specific interstellar medium features that cause scintillation. We searched for interstellar medium counterparts to all…

High Energy Astrophysical Phenomena · Physics 2025-06-04 Ashley M. Stock , Marten H. van Kerkwijk

In recent years, instrumentation enabling pulsar observations with unprecedentedly high fractional bandwidth has been under development which can be used to substantially improve the precision of pulsar timing experiments. The traditional…

Pulsars have been primarily detected by their narrow pulses or periodicity in time domain data. Interferometric surveys for pulsars are challenging due to the trade-off between beam sensitivity and beam size and the corresponding tradeoff…

High Energy Astrophysical Phenomena · Physics 2024-07-26 Jitendra Salal , Shriharsh P. Tendulkar , Visweshwar Ram Marthi

We derive the distribution of flux density of a compact source exhibiting strong diffractive scintillation. Our treatment accounts for arbitrary spectral averaging, spatially-extended source emission, and the possibility of intrinsic…

Instrumentation and Methods for Astrophysics · Physics 2012-08-09 Michael D. Johnson , Carl R. Gwinn

We present here the results from an extensive scintillation study of twenty pulsars in the dispersion measure (DM) range 3 - 35 pc cm^-3 caried out using the Ooty Radio Telescope (ORT) at 327 MHz, to investigate the distribution of ionized…

Astrophysics · Physics 2009-10-30 N. D. Ramesh Bhat , Yashwant Gupta , A. Pramesh Rao

The flux density spectra of radio pulsars are known to be steep and, to first order, described by a power-law relationship of the form S_{\nu} \propto \nu^{\alpha}, where S_{\nu} is the flux density at some frequency \nu and \alpha is the…

Solar and Stellar Astrophysics · Physics 2015-06-15 Samuel D. Bates , Duncan R. Lorimer , Joris P. W. Verbiest

The radio pulse from a pulsar can be temporally broadened by multipath scattering in the interstellar medium and by instrumental effects within the radio telescope. The observed pulse shape is a convolution of the intrinsic one with the…

Instrumentation and Methods for Astrophysics · Physics 2016-03-09 M. M. McKinnon

Pulsar scintillation allows a glimpse into small-scale plasma structures in the interstellar medium, if we can infer their properties from the scintillation pattern. With Very Long Baseline Interferometry and working in delay-delay rate…

Instrumentation and Methods for Astrophysics · Physics 2019-08-07 Dana Simard , Ue-Li Pen , Visweshwar Ram Marthi , Walter Brisken

This paper investigates the number of scatterings a photon undergoes in random walks before escaping from a medium. The number of scatterings in random walk processes is commonly approximated as $\tau+\tau^2$ in the literature, where $\tau$…

Astrophysics of Galaxies · Physics 2023-12-27 Kwang-Il Seon , Hyung-Joe Kim , Hee-Gyeong Kim , Hyeon Jeong Youn

We present first results from a LOFAR census of non-recycled pulsars. The census includes almost all such pulsars known (194 sources) at declinations ${\rm Dec}> 8^\circ$ and Galactic latitudes $|{\rm Gb}| > 3^\circ$, regardless of their…

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

The HTRU-S Low Latitude survey data within 1$^{\circ}$of the Galactic Centre (GC) were searched for pulsars using the Fast Folding Algorithm (FFA). Unlike traditional Fast Fourier Transform (FFT) pipelines, the FFA optimally folds the data…

A search for pulse signals was carried out in a new sky area included in the monitoring program for the search for pulsars and transients. Processing of several months data recorded in six frequency channels with a total bandwidth of 2.5…

High Energy Astrophysical Phenomena · Physics 2022-07-20 V. A. Samodurov , S. A. Tyul'bashev , M. O. Toropov , S. V. Logvinenko

We report on a recent global VLBI experiment in which we study the scatter broadening of pulsars in the spatial and time domain simultaneously. Depending on the distribution of scattering screen(s), geometry predicts that the less spatially…

Instrumentation and Methods for Astrophysics · Physics 2013-08-20 Olaf Wucknitz

The interstellar scintillation observed in radio pulsars arises from interference between electromagnetic waves scattered by electron density fluctuations in the turbulent interstellar plasma, providing a critical tool for probing the…