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In this paper, we describe a novel experiment for the accurate estimation of pulsar dispersion measures using the Giant Metre-wave Radio Telescope. This experiment was carried out for a sample of twelve pulsars, over a period of more than…

Astrophysics · Physics 2009-11-10 A. L. Ahuja , Y. Gupta , D. Mitra , A. K. Kembhavi

We present an analysis of the variations seen in the dispersion measures (DMs) of 20 millisecond pulsars observed as part of the Parkes Pulsar Timing Array project. We carry out a statistically rigorous structure function analysis for each…

Making precise measurements of pulsar dispersion measures (DMs) and applying suitable corrections for them is amongst the major challenges in high-precision timing programmes such as pulsar timing arrays (PTAs). While the advent of…

High Energy Astrophysical Phenomena · Physics 2022-05-25 Dilpreet Kaur , N. D. Ramesh Bhat , Shi Dai , Samuel J. McSweeney , Ryan M. Shannon , Sanjay Kudale , Willem van Straten

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…

In an earlier paper (Ahuja, et al, 2005), based on simultaneous multi-frequency observations with the Giant Metrewave Radio Telescope (GMRT), we reported the variation of pulsar dispersion measures (DMs) with frequency. A few different…

Astrophysics · Physics 2008-11-26 Amrit Lal Ahuja , Dipanjan Mitra , Yashwant Gupta

Radio pulses from pulsars are affected by plasma dispersion, which results in a frequency-dependent propagation delay. Variations in the magnitude of this effect lead to an additional source of red noise in pulsar timing experiments,…

High-precision measurements of the pulsar dispersion measure (DM) are possible using telescopes with low-frequency wideband receivers. We present an initial study of the application of the wideband timing technique, which can simultaneously…

We analyze deterministic and random temporal variations in dispersion measure (DM) from the full three-dimensional velocities of pulsars with respect to the solar system, combined with electron-density variations on a wide range of length…

High Energy Astrophysical Phenomena · Physics 2016-09-29 Michael T. Lam , James M. Cordes , Shami Chatterjee , Megan L. Jones , Maura A. McLaughlin , John W. Armstrong

We analyse dispersion measure (DM) variations in six years of radio observations of more than 160 young pulsars, all gamma ray candidates for the Fermi gamma ray telescope mostly located close to the Galactic plane. DMs were fit across 256…

Astrophysics of Galaxies · Physics 2015-06-16 E. Petroff , M. J. Keith , S. Johnston , W. van Straten , R. M. Shannon

We analyze the frequency dependence of the dispersion measure (DM), the column density of free electrons to a pulsar, caused by multipath scattering from small scale electron-density fluctuations. The DM is slightly different along each…

Instrumentation and Methods for Astrophysics · Physics 2016-01-21 J. M. Cordes , R. M. Shannon , D. R. Stinebring

We present the pulse arrival times and high-precision dispersion measure estimates for 14 millisecond pulsars observed simultaneously in the 300-500 MHz and 1260-1460 MHz frequency bands using the upgraded Giant Metrewave Radio Telescope…

We report here on the timing of 597 pulsars over the last four years with the MeerKAT telescope. We provide Times-of-Arrival, pulsar ephemeris files and per-epoch measurements of the flux density, dispersion measure (DM) and rotation…

High Energy Astrophysical Phenomena · Physics 2024-04-03 M. J. Keith , S. Johnston , A. Karastergiou , P. Weltevrede , M. E. Lower , A. Basu , B. Posselt , L. S. Oswald , A. Parthasarathy , A. D. Cameron , M. Serylak , S. Buchner

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project has the primary goal of detecting and characterizing low-frequency gravitational waves through high-precision pulsar timing. The mitigation of interstellar…

High Energy Astrophysical Phenomena · Physics 2021-07-07 Megan L. Jones , Maura A. McLaughlin , Jayanta Roy , Michael T. Lam , James M. Cordes , David L. Kaplan , Bhaswati Bhattacharyya , Lina Levin

We present our results of pulse broadening time estimates and the study of the frequency scaling of this quantity for 60 pulsars based on actual multi-frequency scattering estimates. This research was based on our own measurements,…

Solar and Stellar Astrophysics · Physics 2015-06-23 Wojciech Lewandowski , Magdalena Kowalinska , Jaroslaw Kijak

The ionized interstellar medium disperses pulsar radio signals, resulting in a stochastic time-variable delay known as the dispersion measure (DM) noise. In the wideband paradigm of pulsar timing, we measure a DM together with a time of…

Instrumentation and Methods for Astrophysics · Physics 2025-08-27 Abhimanyu Susobhanan , Rutger van Haasteren

The pulsar timing array systems have reported a detection of a nanohertz-band stochastic gravitational wave background in our galaxy. It is of interest to use this observation to probe modified gravity and to forecast the sensitivity with…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-19 Jonathan Grée , Qiuyue Liang , Elisa G. M. Ferreira

We report on the results of multi-frequency follow-up observations of three pulsars (PSRs J0026+6320, J2208+5500 and J2217+5733) discovered with the Giant Metrewave Radio Telescope (GMRT). These observations were carried out with the GMRT…

High Energy Astrophysical Phenomena · Physics 2019-01-07 Mayuresh P. Surnis , Bhal Chandra Joshi , Maura A. McLaughlin , Krishnakumar M. A. , Manoharan P. K. , Arun Naidu

Context. High-precision pulsar-timing experiments are affected by temporal variations of the Dispersion Measure (DM), which are related to spatial variations in the interstellar electron content. Correcting for DM variations relies on the…

Pulsar dispersion measure (DM) accounts for the total electron content between a pulsar and us. High-precision observations for projects of pulsar timing arrays show temporal DM variations of millisecond pulsars. The aim of this paper is to…

Instrumentation and Methods for Astrophysics · Physics 2018-08-01 P. F. Wang , J. L. Han

Modeling of frequency-dependent effects, contributed by the turbulence in the free electron density of interstellar plasma, is required to enable the detection of the expected imprints from the stochastic gravitational-wave (GW) background…

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