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The observable time delays between the multiple images of strong lensing systems with time variable sources can provide us with some valuable information to probe the expansion history of the Universe. Estimation of these time delays can be…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Amir Aghamousa , Arman Shafieloo

Established image recovery methods in fast ultrasound imaging, e.g. delay-and-sum, trade the image quality for the high frame rate. Cutting-edge inverse scattering methods based on compressed sensing (CS) disrupt this tradeoff via a priori…

Medical Physics · Physics 2019-03-15 Martin F. Schiffner

We have measured variations in scattering time scales in the Crab Pulsar over a 30-year period, using observations made at 610 MHz with the 42-ft telescope at Jodrell Bank Observatory. Over more recent years, where regular Lovell Telescope…

High Energy Astrophysical Phenomena · Physics 2018-07-18 J. W. McKee , A. G. Lyne , B. W. Stappers , C. G. Bassa , C. A. Jordan

We apply a recently proposed method for the analysis of time series from systems with delayed feedback to experimental data generated by a CO_2 laser. The method is able to estimate the delay time with an error of the order of the sampling…

chao-dyn · Physics 2009-10-31 M. J. Bünner , M. Ciofini , A. Giaquinta , R. Hegger , H. Kantz , R. Meucci , A. Politi

Distinguishing between the instantaneous and delayed scatterers in synthetic aperture radar (SAR) images is important for target identification and characterization. To perform this task, one can use the autocorrelation analysis of…

Image and Video Processing · Electrical Eng. & Systems 2019-09-24 Mikhail Gilman , Semyon Tsynkov

We have measured the scattering timescale, $\tau$, and the scattering spectral index, $\alpha$, for 84 single-component pulsars. Observations were carried out with the MeerKAT telescope as part of the Thousand-Pulsar-Array programme in the…

Dispersive delays due to the Solar wind introduce excess noise in high-precision pulsar timing experiments, and must be removed in order to achieve the accuracy needed to detect, e.g., low-frequency gravitational waves. In current pulsar…

We have made high-resolution, high-sensitivity dynamic spectra of a sample of strong pulsars at 430 MHz with the Arecibo radiotelescope. For 4 pulsars we find faint but sharply delineated features in the secondary spectra. These are…

We present an accurate spectral integral method (SIM) for the analyses of scattering from multiple circular perfect electric conductor (PEC) cylinders. It solves the coupled surface integral equations by using the Fourier series and…

Computational Physics · Physics 2023-05-22 Qing Huo Liu , Siwei Wan , Chunhui Zhu

Scattering hinders the passage of light through random media and consequently limits the usefulness of optical techniques for sensing and imaging. Thus, methods for increasing the transmission of light through such random media are of…

Optics · Physics 2014-06-23 Curtis Jin , Raj Rao Nadakuditi , Eric Michielssen , Stephen Rand

The recent development of $\theta\mhyphen\theta$ techniques in pulsar scintillometry has opened the door for new high resolution imaging techniques of the scattering medium. By solving the phase retrieval problem and recovering the…

Instrumentation and Methods for Astrophysics · Physics 2023-08-09 Daniel Baker , Walter Brisken , Marten H. van Kerkwijk , Rik van Lieshout , Ue-Li Pen

We report on findings from scintillation analyses using high-cadence observations of eight canonical pulsars with observing baselines ranging from one to three years. We obtain scintillation bandwidth and timescale measurements for all…

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…

The turbulent nature of the ionised interstellar medium (IISM) causes dispersion measure (DM) and scattering variations in pulsar timing measurements. To improve precision of gravitational wave measurements, pulsar timing array (PTA)…

High Energy Astrophysical Phenomena · Physics 2025-11-06 A. D. Kulkarni , R. M. Shannon , D. J. Reardon , M. T. Miles

The dynamic spectrum of a radio pulsar is an in-line digital hologram of the ionised interstellar medium. It has previously been demonstrated that such holograms permit image reconstruction, in the sense that one can determine an…

Astrophysics · Physics 2009-11-13 Mark Walker , Leon Koopmans , Dan Stinebring , Willem van Straten

Interstellar scattering causes broadening and distortion to the mean pulse profiles and polarization position angle (PPA) curves, especially to the pulse profiles observed at lower frequency. This paper has implemented a method to recover…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Abdujappar Rusul , Ali Esamdin , Alim Kerim , Dilnur Abdurixit , Hongguang Wang , Xiao-Ping Zheng

In our previous paper (Popov et al. (2016)) we investigated properties of the ionized interstellar medium in the direction of three distant pulsars: B1641-45, B1749-28, and B1933+16. We found that uniformly distributed scattering material…

Astrophysics of Galaxies · Physics 2018-08-15 E. N. Fadeev

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

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…