no code implementations • 22 Nov 2022 • Sotiris Anagnostidis, Arne Thomsen, Tomasz Kacprzak, Tilman Tröster, Luca Biggio, Alexandre Refregier, Thomas Hofmann
In this work, we aim to improve upon two-point statistics by employing a \textit{PointNet}-like neural network to regress the values of the cosmological parameters directly from point cloud data.
1 code implementation • 11 Nov 2021 • David Schaurecker, Yin Li, Jeremy Tinker, Shirley Ho, Alexandre Refregier
Generative deep learning methods built upon Convolutional Neural Networks (CNNs) provide a great tool for predicting non-linear structure in cosmology.
no code implementations • 7 Jun 2019 • Janis Fluri, Tomasz Kacprzak, Aurelien Lucchi, Alexandre Refregier, Adam Amara, Thomas Hofmann, Aurel Schneider
We present the cosmological results with a CNN from the KiDS-450 tomographic weak lensing dataset, constraining the total matter density $\Omega_m$, the fluctuation amplitude $\sigma_8$, and the intrinsic alignment amplitude $A_{\rm{IA}}$.
Cosmology and Nongalactic Astrophysics
no code implementations • 23 Jul 2018 • Janis Fluri, Tomasz Kacprzak, Aurelien Lucchi, Alexandre Refregier, Adam Amara, Thomas Hofmann
We find that, for a shape noise level corresponding to 8. 53 galaxies/arcmin$^2$ and the smoothing scale of $\sigma_s = 2. 34$ arcmin, the network is able to generate 45% tighter constraints.
Cosmology and Nongalactic Astrophysics
no code implementations • 23 Jan 2018 • Jörg Herbel, Tomasz Kacprzak, Adam Amara, Alexandre Refregier, Aurelien Lucchi
We find that our approach is able to accurately reproduce the SDSS PSF at the pixel level, which, due to the speed of both the model evaluation and the parameter estimation, offers good prospects for incorporating our method into the $MCCL$ framework.
3 code implementations • 28 Sep 2016 • Joel Akeret, Chihway Chang, Aurelien Lucchi, Alexandre Refregier
We employ a special type of Convolutional Neural Network, the U-Net, that enables the classification of clean signal and RFI signatures in 2D time-ordered data acquired from a radio telescope.
Instrumentation and Methods for Astrophysics
1 code implementation • 27 Apr 2015 • Joel Akeret, Alexandre Refregier, Adam Amara, Sebastian Seehars, Caspar Hasner
We first review the principles of ABC and discuss its implementation using a Population Monte-Carlo (PMC) algorithm and the Mahalanobis distance metric.
Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics Computation
1 code implementation • 26 Oct 2007 • Adam Amara, Alexandre Refregier
For a future DUNE-like full sky survey, we find that, for cases with mild redshift evolution, the variance of the additive systematic signal should be kept below 10^-7 to ensure biases on cosmological parameters that are sub-dominant to the statistical errors.
no code implementations • 6 Feb 2007 • Jason D. Rhodes, Richard Massey, Justin Albert, Nicholas Collins, Richard S. Ellis, Catherine Heymans, Jonathan P. Gardner, Jean-Paul Kneib, Anton Koekemoer, Alexie Leauthaud, Yannick Mellier, Alexandre Refregier, James E. Taylor, Ludovic van Waerbeke
We derive a parametric correction for the effect of CTE on the shapes of objects in the COSMOS field as a function of observation date, position within the ACS WFC field, and object flux.
1 code implementation • 24 Aug 2004 • Richard Massey, Alexandre Refregier
The shapelets method for image analysis is based upon the decomposition of localised objects into a series of orthogonal components with convenient mathematical properties.
no code implementations • 7 May 1999 • Jason Rhodes, Alexandre Refregier, Ed Groth
The weak distortions produced by gravitational lensing in the images of background galaxies provide a method to measure directly the distribution of mass in the universe.