Publications related to Observational astronomy

Time-Delay Cosmography: Measuring the Hubble Constant and Other Cosmological Parameters with Strong Gravitational Lensing

Frédéric Courbin, Martin Raoul Robert Millon

Multiply lensed images of a same source experience a relative time delay in the arrival of photons due to the path length difference and the different gravitational potentials the photons travel through. This effect can be used to measure absolute distance ...

Springer2024

The Pristine dwarf galaxy survey-V. The edges of the dwarf galaxy Hercules

Pascale Jablonka, Nicolas Lawrence Etienne Longeard

We present a new spectroscopic study of 175 stars in the vicinity of the dwarf galaxy Hercules (d similar to 132 kpc) with data from the Anglo-Australian Telescope and its AAOmega spectrograph together with the Two Degree Field multi-object system to solve ...

OXFORD UNIV PRESS2023

Potential scientific synergies in weak lensing studies between the CSST and Euclid space probes

Jean-Paul Richard Kneib, Huanyuan Shan, Jean-Luc Starck

Aims. With the next generation of large surveys poised to join the ranks of observational cosmology in the near future, it is important to explore their potential synergies and to maximize their scientific outcomes. In this study, we aim to investigate the ...

EDP SCIENCES S A2023

Euclid preparation XXII. Selection of quiescent galaxies from mock photometry using machine learning

Frédéric Courbin, Georges Meylan, Gianluca Castignani, Austin Chandler Peel, Maurizio Martinelli, Yi Wang, Richard Massey, Fabio Finelli, Marcello Farina

The Euclid Space Telescope will provide deep imaging at optical and near-infrared wavelengths, along with slitless near-infrared spectroscopy, across similar to 15 000deg(2) of the sky. Euclid is expected to detect similar to 12 billion astronomical source ...

EDP SCIENCES S A2023

In situ monitoring of femtosecond laser-induced modifications in dielectrics

Olivier Bernard

Over the last decades, the progress made in the generation of laser pulses shorter than a picosecond (10^-12 s) has allowed us to reach extreme optical power intensities exceeding 10^15 W cm^-2. This tremendous power has triggered an abundance of original ...

EPFL2023

Model-based electron density estimation using multiple diagnostics on TCV

Olivier Sauter, Federico Alberto Alfredo Felici, Cristian Galperti

Estimation of the dynamic evolution of the electron plasma density during a tokamak discharge is crucial since it directly affects the plasma performance, confinement and stability. Therefore it needs to be monitored and controlled. Knowledge of the densit ...

ELSEVIER SCIENCE SA2023

Element- and enantiomer-selective visualization of molecular motion in real-time

Majed Chergui, Malte Oppermann, Jérémy Raymond Jean Maurice Rouxel

Ultrafast optical-domain spectroscopies allow to monitor in real time the motion of nuclei in molecules. Achieving element-selectivity had to await the advent of time resolved X-ray spectroscopy, which is now commonly carried at X-ray free electron lasers. ...

Nature Portfolio2023

The imprint of galaxy mergers on satellite planes in a cosmological context

Oliver Müller

Flattened and kinematically correlated planes of dwarf satellite galaxies have been observed in the Local Volume. The slinging out of satellites during host galaxy mergers has been suggested as a formation mechanism for these peculiar structures. We statis ...

2023

The very knotty lenser: Exploring the role of regularization in source and potential reconstructions using Gaussian process regression

Georgios Vernardos

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 included. Regulariza ...

OXFORD UNIV PRESS2022

Euclid: Searching for pair-instability supernovae with the Deep Survey

Frédéric Courbin, Georges Meylan, Giovanni Longo, Yi Wang, Richard Massey

Pair-instability supernovae are theorized supernovae that have not yet been observationally confirmed. They are predicted to exist in low-metallicity environments. Because overall metallicity becomes lower at higher redshifts, deep near-infrared transient ...

EDP SCIENCES S A2022

DARKFLUX: A new tool to analyze indirect-detection spectra of next-generation dark matter models

Emma Elizabeth Tolley

We present DARKFLUX, a software tool designed to analyze indirect-detection signatures for next-generation models of dark matter (DM) with multiple annihilation channels. Version 1.0 of this tool accepts user-generated models with 2 -> 2 tree-level dark ma ...

ELSEVIER2022

Toward a Collective Agenda on AI for Earth Science Data Analysis

Devis Tuia, Jan Dirk Wegner

In past years, we have witnessed the fields of geosciences and remote sensing and artificial intelligence (AI) become closer. Thanks to the massive availability of observational data, improved simulations, and algorithmic advances, these disciplines have f ...

2021

Direct observation of multiband transport in magnonic Penrose quasicrystals via broadband and phase-resolved spectroscopy

Dirk Grundler, Sho Watanabe, Mohammad Hamdi, Vinayak Shantaram Bhat, Korbinian Baumgärtl

Quasicrystals are aperiodically ordered structures with unconventional rotational symmetry. Their peculiar features have been explored in photonics to engineer bandgaps for light waves. Magnons (spin waves) are collective spin excitations in magnetically o ...

2021

The completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: 1000 multi-tracer mock catalogues with redshift evolution and systematics for galaxies and quasars of the final data release

Jean-Paul Richard Kneib, Cheng Zhao, Anand Stéphane Raichoor, Amélie Tamone

We produce 1000 realizations of synthetic clustering catalogues for each type of the tracers used for the baryon acoustic oscillation and redshift space distortion analysis of the Sloan Digital Sky Surveys-IV extended Baryon Oscillation Spectroscopic Surve ...

OXFORD UNIV PRESS2021

Towards Efficient and Accurate Numerical Simulations of Galaxies using Task-based Parallelism and Application to Dwarf Galaxies

Loïc Hausammann

Numerical simulations are of a tremendous help to understand the growth of non-linear cosmological structures and how they lead to the formation of galaxies. In recent years, with the goal of improving their prediction power, new hydrodynamical techniques ...

EPFL2021

The Polarity Reversal of Lightning‐Generated Sky Wave

Farhad Rachidi-Haeri, Marcos Rubinstein, Mohammad Azadifar, Wenhao Hou

The polarity reversal of the lightning‐generated first sky wave as a function of the observation distance is studied using a novel approach combining the finite‐difference time domain (FDTD) method and the superposition principle of electromagnetic waves. ...

2020

Sun-synchronous repeat ground tracks and other useful orbits for future space missions

Sun Hee Kim, Luzius Gregor Kronig

The development of oceanography and meteorology has greatly benefited from satellite-based data of Earth's atmosphere and ocean. Traditional Earth observation missions have utilised Sun-synchronous orbits with repeat ground tracks due to their advantages i ...

2020

TDCOSMO. IV. Hierarchical time-delay cosmography - joint inference of the Hubble constant and galaxy density profiles

Frédéric Courbin, Martin Raoul Robert Millon, Aymeric Alexandre Galan, Adriano Agnello

The H0LiCOWcollaboration inferred via strong gravitational lensing time delays a Hubble constant value of H0 = 73 :3+1:7 1:8 km s 1 Mpc 1, describing deflector mass density profiles by either a power-law or stars (constant mass-to-light ratio) plus standar ...

EDP SCIENCES S A2020

Methods for strong gravitational lens detection and analysis using machine learning and high performance computing

Christoph Ernst René Schäfer

The study of strong gravitational lenses is a relatively new scientific field in astronomy with many applications in cosmology. Its unique observables allow astronomers to trace dark matter, determine the expansion of the universe and study galaxy evolutio ...

EPFL2020

A microphotonic astrocomb

Tobias Kippenberg, Michael Wolfgang Geiselmann, Junqiu Liu, Tobias Herr, Miles Henry Anderson, Stefan Kundermann

Earth-like planets, dark energy and variability of fundamental physical constants can be discovered by observing wavelength shifts in the optical spectra of astronomical objects(1-5). These wavelength shifts are so tiny that exquisitely accurate and precis ...

Nature Publishing Group2019