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In addition to the maximum likelihood approach, there are two other methods which are commonly used to reconstruct the true redshift distribution from photometric redshift datasets: one uses a deconvolution method, and the other a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Ravi K. Sheth , Graziano Rossi

The inversion of a gravitational lens system is, as is well known, plagued by the so-called mass-sheet degeneracy: one can always rescale the density distribution of the lens and add a constant-density mass-sheet such that the, also…

Astrophysics · Physics 2009-11-13 J. Liesenborgs , S. De Rijcke , H. Dejonghe , P. Bekaert

High redshift sources suffer from magnification or demagnification due to weak gravitational lensing by large scale structure. One consequence of this is that the distance-redshift relation, in wide use for cosmological tests, suffers…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Madhura Killedar , Paul D. Lasky , Geraint F. Lewis , Chris J. Fluke

The inversion of gravitational lens systems is hindered by the fact that multiple mass distributions are often equally compatible with the observed properties of the images. Besides using clear examples to illustrate the effect of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 J. Liesenborgs , S. De Rijcke

Reconstructing lens potentials and lensed sources can easily become an underconstrained problem, even when the degrees of freedom are low, due to degeneracies, particularly when potential perturbations superimposed on a smooth lens are…

Astrophysics of Galaxies · Physics 2022-07-27 Georgios Vernardos , Leon V. E. Koopmans

A solution to the inversion problem of scattering would offer aberration-free diffraction-limited 3D images without the resolution and depth-of-field limitations of lens-based tomographic systems. Powerful algorithms are increasingly being…

Diffusion models have established new state of the art in a multitude of computer vision tasks, including image restoration. Diffusion-based inverse problem solvers generate reconstructions of exceptional visual quality from heavily…

Image and Video Processing · Electrical Eng. & Systems 2024-08-21 Zalan Fabian , Berk Tinaz , Mahdi Soltanolkotabi

Learning-based and data-driven techniques have recently become a subject of primary interest in the field of reconstruction and regularization of inverse problems. Besides the development of novel methods, yielding excellent results in…

Machine Learning · Statistics 2023-12-22 Luca Ratti

Analysis of galaxy--galaxy strong lensing systems is strongly dependent on any prior assumptions made about the appearance of the source. Here we present a method of imposing a data-driven prior / regularisation for source galaxies based on…

Instrumentation and Methods for Astrophysics · Physics 2022-11-09 Konstantin Karchev , Noemi Anau Montel , Adam Coogan , Christoph Weniger

Image reconstruction under multiple light scattering is crucial in a number of applications such as diffraction tomography. The reconstruction problem is often formulated as a nonconvex optimization, where a nonlinear measurement model is…

Computer Vision and Pattern Recognition · Computer Science 2018-07-04 Yu Sun , Zhihao Xia , Ulugbek S. Kamilov

We revisit the issue of non-parametric gravitational lens reconstruction and present a new method to obtain the cluster mass distribution using strong lensing data without using any prior information on the underlying mass. The method…

Astrophysics · Physics 2009-10-07 J. M. Diego , P. Protopapas , H. B Sandvik , M. Tegmark

Modeling strong gravitational lenses in order to quantify the distortions in the images of background sources and to reconstruct the mass density in the foreground lenses has traditionally been a difficult computational challenge. As the…

Instrumentation and Methods for Astrophysics · Physics 2022-07-05 Alexandre Adam , Laurence Perreault-Levasseur , Yashar Hezaveh

Combining redshift and galaxy shape information offers new exciting ways of exploiting the gravitational lensing effect for studying the large scales of the cosmos. One application is the three-dimensional reconstruction of the matter…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Patrick Simon , Andy Taylor , Jan Hartlap

The fraction of high-redshift sources which are multiply-imaged by intervening galaxies is strongly dependent on the cosmological constant, and so can be a useful probe of the cosmological model. However its power is limited by various…

Astrophysics · Physics 2009-10-31 Daniel J. Mortlock , Rachel L. Webster

Inverse scattering problems are critical in electromagnetic imaging and medical diagnostics but are challenged by their nonlinearity and diverse measurement scenarios. This paper proposes a physics-informed deep contrast source inversion…

Computational Physics · Physics 2025-08-15 Haoran Sun , Daoqi Liu , Hongyu Zhou , Maokun Li , Shenheng Xu , Fan Yang

We introduce a new method for constraining the redshift distribution of a set of galaxies, using weak gravitational lensing shear. Instead of using observed shears and redshifts to constrain cosmological parameters, we ask how well the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 D. Wittman , W. A. Dawson

Weak lensing is a potentially robust and model-independent cosmological probe, but its accuracy is dependent on knowledge of the redshift distribution of the source galaxies used. The most robust way to determine the redshift distribution…

Astrophysics · Physics 2009-11-10 Mustapha Ishak , Christopher M. Hirata

We propose a new technique, which we call the lens parallax method, to determine simultaneously the redshift distribution of the faint blue galaxies and the mass distributions of foreground clusters of galaxies. The method is based on…

Astrophysics · Physics 2009-10-28 Matthias Bartelmann , Ramesh Narayan

The redshift distribution of galaxy lenses in known gravitational lens systems provides a powerful test that can potentially discriminate amongst cosmological models. However, applications of this elegant test have been curtailed by two…

Astrophysics · Physics 2009-06-23 Pedro R. Capelo , Priyamvada Natarajan

Phase retrieval is a nonlinear inverse problem that arises in a wide range of imaging modalities, from electron microscopy to Fourier ptychography. In particular, the reconstruction is facilitated when the sensing matrix is i.i.d. random,…