Publications associées à Astronomie amateur

GHOST commissioning science results - II: a very metal-poor star witnessing the early galactic assembly

This study focuses on Pristine_180956.78-294759.8 (hereafter P180956, [Fe/H] = -1.95 +/- 0.02), a star selected from the Pristine Inner Galaxy Survey (PIGS), and followed-up with the recently commissioned Gemini High-resolution Optical SpecTrograph (GHOST) ...

Oxford Univ Press2024

Performance of the Quasar Spectral Templates for the Dark Energy Spectroscopic Instrument

Jiaxi Yu, Zheng Zheng

Millions of quasar spectra will be collected by the Dark Energy Spectroscopic Instrument (DESI), leading to a fourfold increase in the number of known quasars. High-accuracy quasar classification is essential to tighten constraints on cosmological paramete ...

IOP Publishing Ltd2023

Gravitationally lensed quasars in Gaia - IV. 150 new lenses, quasar pairs, and projected quasars

Frédéric Courbin, Aymeric Alexandre Galan, Cameron Alexander Campbell Lemon, Adriano Agnello

We report the spectroscopic follow-up of 175 lensed quasar candidates selected using Gaia Data Release 2 observations following Paper III of this series. Systems include 86 confirmed lensed quasars and a further 17 likely lensed quasars based on imaging an ...

OXFORD UNIV PRESS2023

A possible dwarf galaxy satellite-of-satellite problem in ?CDM

Yves Revaz, Nick Heesters

Dark matter clusters on all scales, and it is therefore expected that even substructure should host its own substructure. Using the Extragalactic Distance Database, we searched for dwarf-galaxy satellites of dwarf galaxies, that is, satellite-of-satellite ...

EDP SCIENCES S A2023

Constraining quasar structure using high-frequency microlensing variations and continuum reverberation

Frédéric Courbin, Eric Gérard Guy Paic, Hung-Hsu Chan, Vivien François Bonvin, Georgios Vernardos, Martin Raoul Robert Millon

Gravitational microlensing is a powerful tool for probing the inner structure of strongly lensed quasars and for constraining parameters of the stellar mass function of lens galaxies. This is achieved by analysing microlensing light curves between the mult ...

EDP SCIENCES S A2022

The formation of the milky way halo and its dwarf satellites: a NLTE-1D abundance analysis. IV. Segue 1, Triangulumii, and Coma Berenices UFDs

Pascale Jablonka

We present atmospheric parameters and abundances for chemical elements from carbon to barium in metal-poor stars in Segue 1 (seven stars), Coma Berenices (three stars), and Triangulum II (one star) ultrafaint dwarf galaxies (UFDs). The effective temperatur ...

OXFORD UNIV PRESS2021

Exploiting flux ratio anomalies to probe warm dark matter in future large-scale surveys

Frédéric Courbin, Alexey Boyarsky, David Richard Harvey, Amélie Tamone, Wessel Valkenburg

Flux ratio anomalies in strong gravitationally lensed quasars constitute a unique way to probe the abundance of non-luminous dark matter haloes, and hence the nature of dark matter. In this paper, we identify double-imaged quasars as a statistically effici ...

2019

Observations of Sagittarius A* during the pericenter passage of the G2 object with MAGIC

Thomas Günther Bretz

Context. We present the results of a multi-year monitoring campaign of the Galactic center (GC) with the MAGIC telescopes. These observations were primarily motivated by reports that a putative gas cloud (G2) would be passing in close proximity to the supe ...

Edp Sciences S A2017

LEAP: Looking beyond pixels with continuous-space EstimAtion of Point sources

Martin Vetterli, Paul Hurley, Thierry Blu, Matthieu Martin Jean-André Simeoni, Hanjie Pan

Context. Two main classes of imaging algorithms have emerged in radio interferometry: the CLEAN algorithm and its multiple variants, and compressed-sensing inspired methods. They are both discrete in nature, and estimate source locations and intensities on ...

2017

The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis II. Early chemical enrichment

Pascale Jablonka, Pierre North

We present the non-local thermodynamic equilibrium (NLTE) abundances of up to 10 chemical species in a sample of 59 very metal-poor (VMP, -4

Edp Sciences S A2017