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The study of X-ray time-lag spectra in active galactic nuclei (AGN) is currently an active research area, since it has the potential to illuminate the physics and geometry of the innermost region (i.e. close to the putative super-massive…

Instrumentation and Methods for Astrophysics · Physics 2016-06-29 A. Epitropakis , I. E. Papadakis

We study fractional variability as a function of energy from black-hole X-ray binaries on timescales from milliseconds to hundreds of seconds. We build a theoretical model of energy-dependent variability in which the X-ray energy spectrum…

Astrophysics · Physics 2009-11-11 Marek Gierlinski , Andrzej A. Zdziarski

We present a technique which predicts the energy dependent fractional r.m.s for linear correlated variations of a pair of spectral parameters and apply it to an XMM-Newton observation of Mrk 335. The broadband X-ray spectrum can be…

High Energy Astrophysical Phenomena · Physics 2025-01-24 K. Akhila , Ranjeev Misra , Rathin Sarma , Savithri H. Ezhikode , K. Jeena

In QM/MM indirect free energy simulation, QM/MM corrections can be obtained from integration of partial derivatives of alchemical Hamiltonians or from perturbation-based estimators including free energy perturbation (FEP) and acceptance…

Chemical Physics · Physics 2018-10-05 Xiaohui Wang , Zhaoxi Sun

Many statistical properties of the aperiodic variability observed in X-ray radiation from accreting compact objects can be naturally explained by the propagating fluctuations model. This considers variations in mass accretion rate to be…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Adam Ingram , Michiel van der Klis

Timing techniques offer powerful tools to study dynamical astrophysical phenomena. In the X-ray band, they offer the potential of probing accretion physics down to the event horizon. Recent work has used frequency and energy-dependent time…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Abderahmen Zoghbi , Chris Reynolds , Ed Cackett

The power spectrum, as a statistic in Fourier space, is commonly numerically calculated using the fast Fourier transform method to efficiently reduce the computational costs. To alleviate the systematic bias known as aliasing due to the…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-24 Yipeng Wang , Yu Yu

We present a new set of accurate formulae for the computation of random errors in the measurement of atomic and molecular indices. The new expressions are in excellent agreement with numerical simulations. We have found that, in some cases,…

Astrophysics · Physics 2009-10-30 N. Cardiel , J. Gorgas , J. Cenarro , J. J. Gonzalez

We present calculations of the time lags and the coherence function of X-ray photons for a novel model of radiation emission from accretion powered, high-energy sources. Our model involves only Comptonization of soft photons injected near…

Astrophysics · Physics 2009-10-30 Xin-Min Hua , Demosthenes Kazanas , Lev Titarchuk

We present a practical scheme for performing error estimates for Density Functional Theory calculations. The approach which is based on ideas from Bayesian statistics involves creating an ensemble of exchange-correlation functionals by…

Materials Science · Physics 2009-11-11 J. J. Mortensen , K. Kaasbjerg , S. L. Frederiksen , J. K. Norskov , J. P. Sethna , K. W. Jacobsen

Precise measurements of the 21 cm power spectrum are crucial for understanding the physical processes of hydrogen reionization. Currently, this probe is being pursued by low-frequency radio interferometer arrays. As these experiments come…

Period searches in event data have traditionally used the Rayleigh statistic, $R^2$. For X-ray pulsars, the standard has been the $Z^2$ statistic, which sums over more than one harmonic. For $\gamma$-rays, the $H$-test, which optimizes the…

Instrumentation and Methods for Astrophysics · Physics 2017-12-05 G. Belanger

We develop a general method for power spectrum analysis of three dimensional redshift surveys. We present rigorous analytical estimates for the statistical uncertainty in the power and we are able to derive a rigorous optimal weighting…

Astrophysics · Physics 2011-05-05 Hume A. Feldman , Nick Kaiser , John A. Peacock

We present simple XSPEC models for fitting excess variance spectra of AGN. Using a simple Monte-Carlo approach, we simulate a range of spectra corresponding to physical parameters varying, then calculate the resulting variance spectra.…

High Energy Astrophysical Phenomena · Physics 2020-01-08 M. L. Parker , W. N. Alston , Z. Igo , A. C. Fabian

Over the next decade, improvements in cosmological parameter constraints will be driven by surveys of large-scale structure. Its inherent non-linearity suggests that significant information will be embedded in higher correlations beyond the…

Cosmology and Nongalactic Astrophysics · Physics 2017-07-19 Joyce Byun , Alexander Eggemeier , Donough Regan , David Seery , Robert E. Smith

The Encircled Energy Fraction and its quantiles, notably the Half Energy Width, are routinely used to characterize the quality of X-ray optical systems. They are however always quoted without a statistical error. We show how non-parametric…

Instrumentation and Methods for Astrophysics · Physics 2016-01-20 Giuseppe Vacanti

Energy efficiency and its optimization constitute critical tasks in the design of low-power wireless networks. The present work is devoted to the error rate analysis and energy-efficiency optimization of regenerative cooperative networks in…

Information Theory · Computer Science 2015-06-03 Mulugeta K. Fikadu , Paschalis C. Sofotasios , Qimei Cui , Mikko Valkama , George K. Karagiannidis

We present the most extensive analysis of Fourier-based X-ray timing properties of the black hole binary Cygnus X-1 to date, based on 12 years of bi-weekly monitoring with RXTE from 1999 to 2011. Our aim is a comprehensive study of timing…

Low-energy $\mu$SR (LE-$\mu$SR) enables depth-resolved studies of magnetic and electronic properties from the surface into the near-surface region, but the measured transverse-field asymmetry is not an intrinsic constant and depends on…

Instrumentation and Detectors · Physics 2026-04-14 G. Janka , Z. Salman , A. Suter , T. Prokscha

This paper introduces a novel technique to preserve spectral features in lossy compression based on a novel fast Fourier correction algorithm\added{ for regular-grid data}. Preserving both spatial and frequency representations of data is…

Distributed, Parallel, and Cluster Computing · Computer Science 2026-01-06 Congrong Ren , Robert Underwood , Sheng Di , Emrecan Kutay , Zarija Lukic , Aylin Yener , Franck Cappello , Hanqi Guo
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