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Exoplanet transmission spectra, which measure the absorption of light passing through a planet's atmosphere during transit, are most often assessed globally, resulting in a single spectrum per planetary atmosphere. However, the inherent…

Earth and Planetary Astrophysics · Physics 2022-12-21 David Grant , Hannah R. Wakeford

In order to constrain the models describing circumstellar environments, it is necessary to solve the radiative transfer equation in the presence of absorption and scattering, coupled with the equation for radiative equilibrium. However,…

Solar and Stellar Astrophysics · Physics 2021-09-29 Jérémy Perdigon , Gilles Niccolini , Marianne Faurobert

A popular numerical method to model the dynamics of a 'full spectrum' of cosmic rays (CRs), also applicable to radiation/neutrino hydrodynamics (RHD), is to discretize the spectrum at each location/cell as a piecewise power law in 'bins' of…

High Energy Astrophysical Phenomena · Physics 2022-11-30 Philip F. Hopkins

We report optical second-harmonic generation (SHG) in reflection from GaSe crystals of 1 to more than 100 layers using a fundamental picosecond pulsed pump at 1.58 eV and a supercontinuum white light pulsed laser with energies ranging from…

Mesoscale and Nanoscale Physics · Physics 2017-10-10 Yanhao Tang , Krishna C. Mandal , John A. McGuire , Chih Wei Lai

Radiative transfer (RT) problems in which the source function includes a scattering-like integral are typical two-points boundary problems. Their solution via differential equations implies to make hypotheses on the solution itself, namely…

Solar and Stellar Astrophysics · Physics 2015-05-30 E. Simonneau , O. Cardona , L. Crivellari

With a new generation of observatories coming online this decade, the process of characterizing exoplanet atmospheres will need to be reinvented. Currently mostly on the instrumental side, characterization bottlenecks will soon stand by the…

Earth and Planetary Astrophysics · Physics 2022-09-16 Prajwal Niraula , Julien de Wit , Iouli E. Gordon , Robert J. Hargreaves , Clara Sousa-Silva , Roman V. Kochanov

The one dimensional wave equation serves as a basic model for imaging modalities such as seismic which utilize acoustic data reflected back from a layered medium. In 1955 Peterson et al. described a single scattering approximation for the…

Analysis of PDEs · Mathematics 2018-02-02 Peter C. Gibson

This paper explicitly computes the transition densities of a spectrally negative stable process with index greater than one, reflected at its infimum. First we derive the forward equation using the theory of sun-dual semigroups. The…

Probability · Mathematics 2016-11-28 Boris Baeumer , Mihály Kovács , Mark M. Meerschaert , René L. Schilling , Peter Straka

A finite element method for solving the resonance line transfer problem in moving media is presented. The algorithm works in three spatial dimensions on unstructured grids which are adaptively refined by means of an a posteriori error…

Astrophysics · Physics 2009-11-07 E. Meinkoehn , S. Richling

The direct imaging of potentially habitable Exoplanets is one prime science case for the next generation of high contrast imaging instruments on ground-based extremely large telescopes. To reach this demanding science goal, the instruments…

In this paper, we report on very efficient algorithms for the spherical harmonic transform (SHT). Explicitly vectorized variations of the algorithm based on the Gauss-Legendre quadrature are discussed and implemented in the SHTns library…

Computational Physics · Physics 2015-01-08 Nathanaël Schaeffer

We propose a powerful approach to solve Laplace's equation for point sources near a spherical object. The central new idea is to use prolate spheroidal solid harmonics, which are separable solutions of Laplace's equation in spheroidal…

Classical Physics · Physics 2017-03-22 Matt Majic , Baptiste Auguie , Eric C. Le Ru

Refraction deflects photons that pass through atmospheres, which affects transit light curves. Refraction thus provides an avenue to probe physical properties of exoplanet atmospheres and to constrain the presence of clouds and hazes. In…

Earth and Planetary Astrophysics · Physics 2018-01-24 Dennis Alp , Brice-Olivier Demory

Radiative transfer calculations are essential for modeling planetary atmospheres. However, standard methods are computationally demanding and impose accuracy-speed trade-offs. High computational costs force numerical simplifications in…

Earth and Planetary Astrophysics · Physics 2025-11-03 Isaac Malsky , Tiffany Kataria , Natasha E. Batalha , Matthew Graham

This paper investigates the inverse biharmonic scattering problems of identifying the shape and location of the obstacle with phased and phaseless measurement data. A direct imaging method based on reverse time migration is proposed for…

Analysis of PDEs · Mathematics 2026-05-12 Tielei Zhu , Zhihao Ge

We introduce the radiative transfer code Sweep for the cosmological simulation suite Arepo. Sweep is a discrete ordinates method in which the radiative transfer equation is solved under the infinite speed of light, steady state assumption…

Instrumentation and Methods for Astrophysics · Physics 2023-01-25 Toni Peter , Ralf S. Klessen , Guido Kanschat , Simon C. O. Glover , Peter Bastian

Reflection phase imaging provides label-free, high-resolution characterization of biological samples, typically using interferometric-based techniques. Here, we investigate reflection phase microscopy from intensity-only measurements under…

Quantitative Methods · Quantitative Biology 2019-12-18 Alex Matlock , Anne Sentenac , Patrick C. Chaumet , Ji Yi , Lei Tian

Phase-sensitive coherent imaging exploits changes in the phases of backscattered light to observe tiny alterations of scattering structures or variations of the refractive index. But moving scatterers or a fluctuating refractive index…

We propose a method for observing transiting exoplanets with near-infrared high-resolution spectrometers. We aim to create a robust data analysis method for recovering atmospheric transmission spectra from transiting exoplanets over a wide…

Instrumentation and Methods for Astrophysics · Physics 2015-06-17 Erik Aronson , Pierre Waldén , Nikolai Piskunov

Accurately estimating scene lighting is critical for applications such as mixed reality. Existing works estimate illumination by generating illumination maps or regressing illumination parameters. However, the method of generating…

Computer Vision and Pattern Recognition · Computer Science 2024-04-22 Xinlong Ji , Fangneng Zhan , Shijian Lu , Shi-Sheng Huang , Hua Huang