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A new method of matrix template matching is presented in the context of pulsar timing analysis. Pulse arrival times are typically measured using only the observed total intensity light curve. The new technique exploits the additional timing…

Astrophysics · Physics 2017-08-02 W. van Straten

We study theoretical X-ray light curves and polarization properties of accretion-powered millisecond pulsars. We assume that the radiation is produced in two antipodal spots at the neutron star surface which are associated with the magnetic…

Astrophysics · Physics 2009-11-10 Kerttu Viironen , Juri Poutanen

We report our search for \gamma-ray emission in the energy range from 100 MeV to 300 GeV from four Accreting Millisecond Pulsars (AMPs), SAX J1808.4-3658, IGR J00291+5934, XTE J1814-338, and XTE J0929-314. The data are from four-year…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Yi Xing , Zhongxiang Wang

r-mode astroseismology provides a unique way to study the internal composition of compact stars. Due to their precise timing, recycled millisecond radio pulsars present a particularly promising class of sources. Although their thermal…

High Energy Astrophysical Phenomena · Physics 2017-01-25 Kai Schwenzer , Tuğba Boztepe , Tolga Güver , Eda Vurgun

We report the detection of 376.05 Hz (2.66 ms) coherent X-ray pulsations in NICER observations of a transient outburst of the low-mass X-ray binary IGR J17494-3030 in 2020 October/November. The system is an accreting millisecond X-ray…

Purpose: Undersampling is used to reduce the scan time for high-resolution 3D magnetic resonance imaging. In order to achieve better image quality and avoid manual parameter tuning, we propose a probabilistic Bayesian approach to recover…

Image and Video Processing · Electrical Eng. & Systems 2022-10-20 Shuai Huang , James J. Lah , Jason W. Allen , Deqiang Qiu

MAXI J1816-195 is an accreting millisecond X-ray pulsar (AMXP) discovered in 2022. According to the Insight-HXMT data, the pulsations of this source extend all the way to over 100 keV, and its pulse profiles change from a single peak in…

High Energy Astrophysical Phenomena · Physics 2024-03-26 Yuan You , Shuang-Nan Zhang , Zhaosheng Li , Mingyu Ge

Recent constraints on neutron star mass and radius have advanced our understanding of the equation of state (EOS) of cold dense matter. Some of them have been obtained by modeling the pulses of three millisecond X-ray pulsars observed by…

Pulsar timing is used for a variety of applications including tests of fundamental physics, probing the structure of neutron stars, and detecting nanohertz gravitational waves. Development of robust methods and generation of high-quality…

We investigate the dependence of pulse amplitudes of accreting millisecond pulsars on the masses of the neutron stars. Because the pulsation amplitudes are suppressed as the neutron stars become more massive, the probability of detection of…

Astrophysics · Physics 2011-02-11 Feryal Ozel

Improving resolution and sensitivity will widen possible medical applications of magnetic particle imaging. Pulsed excitation promises such benefits, at the cost of more complex hardware solutions and restrictions on drive field amplitude…

We introduce a method for extracting spectral information from energy-resolved light curves folded at the neutron star spin period (known as pulse profiles) in accreting X-ray binaries. Spectra of these sources are sometimes characterized…

High Energy Astrophysical Phenomena · Physics 2023-09-13 Carlo Ferrigno , Antonino D'Aì , Elena Ambrosi

Millisecond pulsars (MSP) are an important subclass of rotation powered pulsars (RPP), traditionally defined as those with $P_s < 20-30$~ms and $B_s \lesssim 10^{10}$~G. We re-examine this definition by applying Gaussian mixture model (GMM)…

High Energy Astrophysical Phenomena · Physics 2023-10-11 Priyam Halder , Satyaki Goswami , Protyusha Halder , Uday Ghosh , Sushan Konar

The measurement of the spin frequency in accreting millisecond X-ray pulsars (AMXPs) is strongly affected by the presence of an unmodeled component in the pulse arrival times called 'timing noise'. We show that it is possible to attribute…

High Energy Astrophysical Phenomena · Physics 2011-02-11 Alessandro Patruno , Rudy Wijnands , Michiel van der Klis

The equation of state of cold supra-nuclear-density matter, such as in neutron stars, is an open question in astrophysics. A promising method for constraining the neutron star equation of state is modelling pulse profiles of thermonuclear…

High Energy Astrophysical Phenomena · Physics 2016-12-28 A. L. Stevens , J. D. Fiege , D. A. Leahy , S. M. Morsink

Despite the fact that pulsars have been observed for almost half a century, many questions have remained unanswered. We use the analysis of X-ray observations in order to study the polar cap region of radio pulsars. The size of the hot…

High Energy Astrophysical Phenomena · Physics 2013-04-19 Andrzej Szary

Approximate message passing (AMP) is an algorithmic framework for solving linear inverse problems from noisy measurements, with exciting applications such as reconstructing images, audio, hyper spectral images, and various other signals,…

Information Theory · Computer Science 2017-02-13 Junan Zhu , Ryan Pilgrim , Dror Baron

NASA's NICER telescope has recently provided evidence for non-dipolar magnetic field structures in rotation-powered millisecond pulsars. These stars are assumed to have gone through a prolonged accretion spin-up phase, begging the question…

High Energy Astrophysical Phenomena · Physics 2022-07-20 Pushpita Das , Oliver Porth , Anna Watts

The Neutron Star Interior Composition Explorer (NICER) mission has provided a unique opportunity to constrain the equation of state of neutron stars by using the technique of pulse-profile modelling. This technique requires accurate and…

General Relativity and Quantum Cosmology · Physics 2021-05-12 G. André Oliva , Francisco Frutos-Alfaro

The relativistic precession model (RPM) is widely-considered as a benchmark framework to interpret quasi-periodic oscillations (QPOs), albeit several observational inconsistencies suggest that the model remains incomplete. The RPM ensures…

General Relativity and Quantum Cosmology · Physics 2025-12-16 Gabriele Bianchini , Orlando Luongo , Marco Muccino