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The CLEAN deconvolution algorithm has well-known limitations due to the restriction of locating point source model components on a discretized grid. In this letter we demonstrate that these limitations are even more pronounced when applying…

Instrumentation and Methods for Astrophysics · Physics 2015-06-12 M. R. Bell , N. Oppermann , A. Crai , T. A. Enßlin

The x-ray near-field speckle-scanning concept is an approach recently introduced to obtain absorption, phase, and dark-field images of a sample. In this paper, we present ways of recovering from a sample its ultrasmall-angle x-ray…

Optics · Physics 2015-07-24 Sebastien Berujon , Eric Ziegler

Black hole spectroscopy is the proposal to observe multiple quasinormal modes in the ringdown of a binary black hole merger. In addition to the fundamental quadrupolar mode, overtones and higher harmonics may be present and detectable in…

General Relativity and Quantum Cosmology · Physics 2022-02-14 Iara Ota , Cecilia Chirenti

We report on an effort to extract and monitor interstellar scintillation parameters in regular timing observations collected for the NANOGrav pulsar timing array. Scattering delays are measured by creating dynamic spectra for each pulsar…

Recently, many different pulsar timing array (PTA) collaborations have reported strong evidence for a common stochastic process in their data sets. The reported amplitudes are in tension with previously computed upper limits. In this paper,…

High Energy Astrophysical Phenomena · Physics 2022-06-29 Aaron D. Johnson , Sarah J. Vigeland , Xavier Siemens , Stephen R. Taylor

We introduce a novel analysis technique for pulsar secondary spectra. The power spectrum of pulsar scintillation (referred to as the "secondary spectrum") shows differential delays and Doppler shifts due to interference from multi-path…

Instrumentation and Methods for Astrophysics · Physics 2020-12-02 Tim Sprenger , Olaf Wucknitz , Robert Main , Daniel Baker , Walter Brisken

We have performed pulse phase resolved spectroscopy of the Cyclotron Resonance Scattering Features (CRSF) of some bright accretion powered X-ray pulsars like 1A 1118-61, Vela X-1, A0535+26, XTE J1946+274, 4U 1907+09, 4U 1626-67 and GX 301-2…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Chandreyee Maitra , Biswajit Paul

While characterization of coherent wavefields is essential to laser, x-ray and electron imaging, sensors measure the squared magnitude of the field, rather than the field itself. Holography or phase retrieval must be used to characterize…

Image and Video Processing · Electrical Eng. & Systems 2020-12-10 David J. Brady , Timothy J. Schulz , Chengyu Wang

This method solves the dual problem of blind deconvolution and estimation of the time waveform of noisy second-order cyclo-stationary (CS2) signals that traverse a Transfer Function (TF) en route to a sensor. We have proven that the…

Machine Learning · Computer Science 2024-03-07 Igor Makienko , Michael Grebshtein , Eli Gildish

The MOST, CoRoT, and Kepler space missions led to the discovery of a large number of intriguing, and in some cases unique, objects among which are pulsating stars, stars hosting exoplanets, binaries, etc. Although the space missions deliver…

Solar and Stellar Astrophysics · Physics 2015-06-17 A. Tkachenko , T. Van Reeth , V. Tsymbal , C. Aerts , O. Kochukhov , J. Debosscher

Context{The high energy emission regions of rotation powered pulsars are studied using folded light curve (FLCs) and phase resolved spectra (PRS).} aims{This work uses the NICER observatory to obtain the highest resolution FLC and PRS of…

High Energy Astrophysical Phenomena · Physics 2021-06-04 M. Vivekanand

Cyclotron resonant scattering features (CRSFs) are the absorption features in the X-ray spectra of strongly magnetized accretion neutron stars (NSs), which are probably the most reliable probe to the surface magnetic fields of NSs. The high…

High Energy Astrophysical Phenomena · Physics 2024-04-19 Xiao Chen , Yuanze Ding , Wei Wang , Osamu Nishimura , Qi Liu , Shuang-Nan Zhang , Mingyu Ge , Fangjun Lu , Jinlu Qu , Liming Song , Shu Zhang

We study the problem of recovering the phase from magnitude measurements; specifically, we wish to reconstruct a complex-valued signal x of C^n about which we have phaseless samples of the form y_r = |< a_r,x >|^2, r = 1,2,...,m (knowledge…

Information Theory · Computer Science 2016-11-17 Emmanuel Candes , Xiaodong Li , Mahdi Soltanolkotabi

In the data analysis of oscillatory systems, methods based on phase reconstruction are widely used to characterize phase-locking properties and inferring the phase dynamics. The main component in these studies is an extraction of the phase…

Data Analysis, Statistics and Probability · Physics 2021-11-22 Erik Gengel , Arkady Pikovsky

Supermassive black hole binaries are one of the primary targets for gravitational wave searches using pulsar timing arrays. Gravitational wave signals from such systems are well represented by parametrized models, allowing the standard…

Instrumentation and Methods for Astrophysics · Physics 2016-01-25 Yan Wang , Soumya D. Mohanty , Fredrick A. Jenet

Photomultiplier tubes (PMTs) are extensively employed as photosensors in neutrino and dark matter detection. The precise charge and timing information extracted from the PMT waveform plays a crucial role in energy and vertex reconstruction.…

Instrumentation and Detectors · Physics 2025-02-14 Jingzhe Tang , Tianying Xiao , Xuan Tang , Yongbo Huang

Circular dichroism spectroscopy is an essential technique for understanding molecular structure and magnetic materials, but spatial resolution is limited by the wavelength of light, and sensitivity sufficient for single-molecule…

We present a method for the measurement of the phase gradient of a wavefront by tracking the relative motion of speckles in projection holograms as a sample is scanned across the wavefront. By removing the need to obtain an un-distorted…

Optics · Physics 2020-03-31 Andrew J. Morgan , Harry M. Quiney , Saša Bajt , Henry N. Chapman

The most ubiquitous form of computational aberration correction for microscopy is deconvolution. However, deconvolution relies on the assumption that the point spread function is the same across the entire field-of-view. This assumption is…

Image and Video Processing · Electrical Eng. & Systems 2025-04-30 Amit Kohli , Anastasios N. Angelopoulos , David McAllister , Esther Whang , Sixian You , Kyrollos Yanny , Federico M. Gasparoli , Bo-Jui Chang , Reto Fiolka , Laura Waller

We present a detailed analysis of observations of the high mass X-ray binary Cen X-3 spanning two consecutive binary orbits performed with the RXTE satellite in early March 1997. The PCA and HEXTE light curves both show a clear reduction in…