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As the interferometers detecting gravitational waves are upgraded, improving their sensitivity, the probability of observing strong lensing increases. Once a detection is made, it will be critical to gain as much information as possible…

High Energy Astrophysical Phenomena · Physics 2023-10-31 Mick Wright , Justin Janquart , Martin Hendry

Within the framework of the internal shock model, we study the luminosity and the variability in gamma-ray bursts from collimated fireballs. In particular we pay attention to the role of the photosphere due to $e^\pm$ pairs produced by…

Astrophysics · Physics 2009-11-07 Shiho Kobayashi , Felix Ryde , Andrew MacFadyen

Modelling the scattering of focused, coherent light by nano-scale structures is oftentimes used to reconstruct or infer geometrical or material properties of structures under investigation in optical scatterometry. This comprises both…

We derive simple formulae for the transmittance $T$ and reflectance $R$ of Gaussian-Schell beams incident upon any stratified dielectric structure by using second-order classical coherence theory in the space-frequency picture. The…

Optics · Physics 2021-02-24 Paulo A. Brandão , João P. Mendonça , S. B. Cavalcanti

We propose and demonstrate an interferometric scheme for measuring the two-dimensional two-point cross-spectral density function in a two-shot manner. Our scheme comprises a Michelson interferometer with a converging lens in one of the arms…

Instrumentation and Detectors · Physics 2018-08-01 Abhinandan Bhattacharjee , Shaurya Aarav , Anand K. Jha

Recent technological advances allowed the coherent optical manipulation of high-energy electron wavepackets with attosecond precision. Here we theoretically investigate the collision of optically-modulated pulsed electron beams with atomic…

Atomic Physics · Physics 2021-04-21 Yuya Morimoto , Peter Hommelhoff , Lars Bojer Madsen

We present GLEAM (Galaxy Line Emission & Absorption Modeling), a Python tool for fitting Gaussian models to emission and absorption lines in large samples of 1D extragalactic spectra. GLEAM is tailored to work well in batch mode without…

Instrumentation and Methods for Astrophysics · Physics 2021-03-08 Andra Stroe , Victor-Nicolae Savu

Diffraction patterns produced by fast He atoms grazingly impinging on a LiF(001) surface are investigated focusing on the influence of the beam collimation. Single- and double- slit collimating devices situated in front of the beam source…

Atomic Physics · Physics 2016-09-21 M. S. Gravielle , J. E. Miraglia

The modelling of gamma-ray burst (GRB) spectra has considerable potential for increasing the understanding of these enigmatic sources. A diversity of ideas and analyses has been generated over the last two decades to explain line features…

Astrophysics · Physics 2009-10-28 M. G. Baring

The influence of the collimating conditions of the incident beam on diffraction patterns produced by grazing scattering of fast atoms off crystal surfaces is studied within a semi-quantum approach, named Surface Initial Value Representation…

Atomic Physics · Physics 2016-02-24 M. S. Gravielle , J. E. Miraglia

This article describes a complete theory of spatial coherence for undulator radiation sources. Current estimations of coherence properties often assume that undulator sources are quasi-homogeneous, like thermal sources, and rely on the…

We calculate the spectrum of blast wave models of gamma-ray burst sources, for various assumptions about the magnetic field density and the relativistic particle acceleration efficiency. For a range of physically plausible models we find…

Astrophysics · Physics 2011-09-30 P. Meszaros , M. J. Rees , H. Papathanassiou

A theory for the characterization of the fourth moment of electromagnetic wave beams is presented in the case when the source is partially coherent. A Gaussian-Schell model is used for the partially coherent random source. The white-noise…

Optics · Physics 2022-01-19 Josselin Garnier , Knut Sølna

We discuss the Gaussian graphical model (GGM; an undirected network of partial correlation coefficients) and detail its utility as an exploratory data analysis tool. The GGM shows which variables predict one-another, allows for sparse…

Methodology · Statistics 2018-02-09 Sacha Epskamp , Lourens J. Waldorp , René Mõttus , Denny Borsboom

Using Gaussian Mixture Model (GMM) and Expectation Maximization Algorithm, we perform an analysis of time duration ($T_{90}$) for \textit{CGRO}/BATSE, \textit{Swift}/BAT and \textit{Fermi}/GBM Gamma-Ray Bursts. The $T_{90}$ distributions of…

High Energy Astrophysical Phenomena · Physics 2016-08-01 En-Bo Yang , Zhi-Bin Zhang , Chul-Sung Choi , Heon-Young Chang

This work is concerned with the construction of Gaussian Beam (GB) solutions for the numerical approximation of wave equations, semi-discretized in space by finite difference schemes. GB are high-frequency solutions whose propagation can be…

Analysis of PDEs · Mathematics 2023-06-12 Umberto Biccari , Enrique Zuazua

3D Gaussian Splatting (3DGS) has emerged as a prominent 3D representation for high-fidelity and real-time rendering. Prior work has coupled physics simulation with Gaussians, but predominantly targets soft, deformable materials, leaving…

Computer Vision and Pattern Recognition · Computer Science 2026-01-15 Bei Huang , Yixin Chen , Ruijie Lu , Gang Zeng , Hongbin Zha , Yuru Pei , Siyuan Huang

We discuss the preliminary results of spectral analysis simulations involving anticipated correlated multi-wavelength observations of gamma-ray bursts (GRBs) using Swift's Burst Alert Telescope (BAT) and the Gamma-Ray Large Area Space…

Astrophysics · Physics 2009-11-13 Michael Stamatikos , Takanori Sakamoto , David L. Band

There are observational facts and theoretical arguments for an origin of gamma-ray bursts in molecular clouds in distant galaxies. If this is true, one could detect a significant flux of GRB prompt and early afterglow X-ray radiation…

Astrophysics · Physics 2009-11-07 S. Sazonov , R. Sunyaev

Accurate beam modeling is important in many radio astronomy applications. In this paper, we focus on beam modeling for 21-cm intensity mapping experiments using radio interferometers, though the techniques also apply to single dish…

Instrumentation and Methods for Astrophysics · Physics 2025-09-16 Michael J. Wilensky , Philip Bull , Nicolas Fagnoni