A5089067120- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Calibration and Measurement Techniques
- Spectroscopy and Laser Applications
- Advanced Image Processing Techniques
- Advanced Vision and Imaging
- Phase Equilibria and Thermodynamics
- Remote Sensing in Agriculture
- Geophysics and Gravity Measurements
- Cosmology and Gravitation Theories
- Crystal Structures and Properties
- Material Science and Thermodynamics
- Pharmacological Effects and Assays
- Image Processing Techniques and Applications
- Image and Signal Denoising Methods
- Nanocluster Synthesis and Applications
Galaxies, Etoiles, Physique et Instrumentation
2015-2024
Centre National de la Recherche Scientifique
2015-2024
Observatoire de Paris
2004-2024
Université Paris Sciences et Lettres
2017-2024
École Polytechnique Fédérale de Lausanne
2015-2024
Délégation Paris 7
2013-2023
Université Paris Cité
2013-2023
Observatoire Cantonal de Neuchâtel
2009-2023
University of Bologna
2021
Sorbonne Université
2020
We present the Pristine survey, a new narrow-band photometric survey focused on metallicity-sensitive Ca H & K lines and conducted in northern hemisphere with wide-field imager MegaCam Canada-France-Hawaii Telescope (CFHT). This paper reviews our overall strategy discusses data processing metallicity calibration. Additionally we review application of these to main aims which are gather large sample most metal-poor stars Galaxy, further characterise faintest Milky Way satellites, map...
The Euclid ERO showcase Euclid's capabilities in advance of its main mission by targeting 17 astronomical objects, including galaxy clusters, nearby galaxies, globular and star-forming regions. A total 24 hours observing time was allocated the early months operation, scientific community engaged through an public data release. We describe development pipeline to create visually compelling images while simultaneously meeting demands within launch leveraging a pragmatic data-driven strategy....
Abstract We study of the role galaxy–galaxy interactions and disk instabilities in producing starburst activity galaxies out to z = 4. For this, we use a sample 387 with robust total star formation rate measurements from Herschel, gas masses Atacama Large Millimeter/submillimeter Array, stellar redshifts multiband photometry, JWST/NIRCam rest-frame optical imaging. Using mass-controlled samples, find an increased fraction interacting regime at all This increase correlates efficiency (SFE)...
We have found evidence for the presence of two distinct ancient stellar components (both ≥10 Gyr old) in Sculptor dwarf spheroidal galaxy. used ESO Wide Field Imager conjunction with Very Large Telescope/FLAMES spectrograph to study properties resolved population out and beyond tidal radius. find that are discernible spatial distribution horizontal branch stars our imaging [Fe/H] vhel distributions large sample spectroscopic measurements. They can be generally described as a "metal-poor"...
We study how the proportion of star-forming galaxies evolves between z=0.8 and z=0 as a function galaxy environment, using [OII] line in emission signature ongoing star formation. Our high-z dataset comprises 16 clusters, 10 groups another 250 poorer field at z=0.4-0.8 from ESO Distant Cluster Survey, plus 9 massive clusters similar redshifts. As local comparison, we use samples systems selected Sloan Digital Sky Survey 0.04< z < 0.08. At most follow broad anticorrelation fraction...
We present VLT FLAMES spectroscopic observations (R ∼ 6500) in the Ca II triplet region for 470 probable kinematic members of Sculptor (Scl) dwarf spheroidal galaxy. The accurate velocities (±2 km s−1) and large area coverage Scl allow us to measure a velocity gradient 7.6+ 3.0−2.2 s−1 deg−1 along projected major axis Scl, likely signature intrinsic rotation. also use our data mass distribution within this system. By considering independently kinematics two distinct stellar components known...
As part of the DART project we have used ESO/2.2m Wide Field Imager in conjunction with VLT/FLAMES GIRAFFE spectrograph to study detailed properties resolved stellar population Fornax dwarf spheroidal galaxy out and beyond its tidal radius. We re-derived structural parameters using our wide field imaging covering radius, analysed spatial distribution stars different ages as selected from Colour-Magnitude Diagram analysis. obtained accurate velocities metallicities spectra CaII triplet...
For the first time we show detailed late-stage chemical evolution history of small nearby dwarf spheroidal galaxy in Local Group. We present results a high resolution (R$\sim$20000) FLAMES/GIRAFFE abundance study at ESO/VLT 81 photometrically selected red giant branch stars central 25$'$ Fornax galaxy. abundances \alfe\ (Mg, Si, Ca and Ti), iron-peak elements (Fe, Ni Cr) heavy (Y, Ba, La, Nd Eu). Our sample was randomly selected, is clearly dominated by younger more metal rich component...
The NIR Ca II triplet absorption lines have proven to be an important tool for quantitative spectroscopy of individual red giant branch stars in the Local Group, providing a better understanding metallicities Milky Way and dwarf galaxies thereby opportunity constrain their chemical evolution processes. An interesting puzzle this field is significant lack extremely metal-poor stars, below [Fe/H]=-3, found classical around using technique. question arises whether these are really absent, or if...
Abstract We demonstrate that low-resolution Ca ii triplet (CaT) spectroscopic estimates of the overall metallicity ([Fe/H]) individual red giant branch (RGB) stars in two nearby dwarf spheroidal galaxies (dSphs) agree to ±0.1–0.2 dex with detailed high-resolution determinations for same over range −2.5 &lt; [Fe/H] −0.5. For this study, we used a sample 129 observed low- and modes VLT/FLAMES Sculptor Fornax dSphs. also present data-reduction steps our analysis show typical accuracy...
Using galaxy clusters from the ESO Distant Cluster Survey, we study how distribution of galaxies along colour-magnitude relation has evolved since z~0.8. While red-sequence in all these are well described by an old, passively evolving population, confirm our previous finding a significant evolution their luminosity as function redshift. When compared to local Universe, high redshift EDisCS exhibit "deficit" faint red galaxies. Combining three different bins, and defining `faint' range 0.4...
As part of the Dwarf galaxies Abundances and Radial-velocities Team (DART) program, we have measured metallicities a large sample stars in four nearby dwarf spheroidal (dSph's): Sculptor, Sextans, Fornax, Carina. The low mean metal abundances presence very old stellar populations these supported view that they are fossils from early universe. However, contrary to naive expectations, find significant lack with below [Fe/H] ~ -3 dex all systems. This suggests gas made up systems had been...
We use VLT/FLAMES intermediate resolution (R~6500) spectra of individual red giant branch stars in the near-infrared CaII triplet (CaT) region to investigate wide-area metallicity properties and internal kinematics Sextans dwarf spheroidal galaxy (dSph). Our final sample consists 174 probable members with accurate line-of-sight velocities (+- 2 km/s) CaT [Fe/H] measurements 0.2 dex). MgI line at 8806.8 Å\, as an empirical discriminator for distinguishing between dSph (giant stars) Galactic...
We investigate how the [O II] properties and morphologies of galaxies in clusters groups at z = 0.4–0.8 depend on projected local galaxy density, compare with field similar redshifts low z. In both nearby distant clusters, higher density regions contain proportionally fewer star-forming galaxies, average equivalent width is independent density. However, current star formation rate (SFR) seems to peak densities ~15-40 Mpc−2. At odds low-z results, high relation between fraction varies from...
We present the results of a dedicated search for extremely metal-poor stars in Fornax, Sculptor, and Sextans dSphs. Five were selected from two earlier VLT/Giraffe HET/HRS surveys subsequently followed up at high spectroscopic resolution with VLT/UVES. All them turned out to have [Fe/H] ≲ −3 three are below ~ −3.5. This constitutes first evidence that classical dSphs Fornax join Sculptor containing suggests all contain stars. One giant = −3.96 ± 0.06 is most star ever observed an external...
The detailed abundances of 23 chemical elements in nine bright red giant branch stars the Carina dwarf spheroidal galaxy are presented based on high-resolution spectra gathered at Very Large Telescope (VLT) and Magellan telescopes. A spherical model atmospheres analysis is applied using standard methods (local thermodynamic equilibrium plane-parallel radiative transfer) to ranging from 380 680 nm. Stellar parameters found be consistent between photometric spectroscopic analyses, both...
We present the results of a set high resolution chemo-dynamical simulations dwarf galaxies in $\Lambda$CDM cosmology. Out an original 3.4 Mpc$^3$/h$^3$ cosmological box, sample 27 systems are zoomed-in from z=70 to z=0. Gas and stellar properties confronted observations greatest details: addition galaxy global properties, we investigate model velocity dispersion profiles, half-light radii, star formation histories, metallicity distributions, [Mg/Fe] abundance ratios. The sustainability...
We use Gaia DR2 astrometric and photometric data, published radial velocities MESA models to infer distances, orbits, surface gravities, effective temperatures for all ultra metal-poor stars ($\FeH<-4.0$ dex) available in the literature. Assuming that these are old ($>11\Gyr$) they expected belong Milky Way halo, we find 42 (18 dwarf 24 giants or sub-giants) currently within $\sim20\kpc$ of Sun map a wide variety orbits. A large fraction those remains confined inner parts halo was likely...
The Beyond Ultra-deep Frontier Fields and Legacy Observations (BUFFALO) is a 101 orbit + parallel Cycle 25 Hubble Space Telescope Treasury program taking data from 2018-2020. BUFFALO will expand existing coverage of the (HFF) in WFC3/IR F105W, F125W, F160W ACS/WFC F606W F814W around each six HFF clusters flanking fields. This additional area has not been observed by HST but already covered deep multi-wavelength datasets, including Spitzer Chandra. As with original program, designed to take...
We study the stellar mass functions (SMFs) of star-forming and quiescent galaxies in 11 galaxy clusters at 1.0<z<1.4, drawn from Gemini Observations Galaxies Rich Early Environments (GOGREEN) survey. Based on more than 500 hours Gemini/GMOS spectroscopy, deep multi-band photometry taken with a range observatories, we probe SMFs down to limit 10^9.7 Msun (10^9.5 for galaxies). At this early epoch, fraction is already highly elevated compared field same redshift. The quenched excess (QFE)...
The orbits of the least chemically enriched stars open a window on formation our Galaxy when it was still in its infancy. common picture is that these low-metallicity are distributed as an isotropic, pressure-supported component since were either accreted from early building blocks assembling Milky Way, or later brought by accretion faint dwarf galaxies. Combining metallicities and radial velocities Pristine LAMOST surveys Gaia DR2 parallaxes proper motions for unprecedented large unbiased...
We used the spectro-photometric information of ∼219 million stars from Gaia ’s Data Release 3 (DR3) to calculate synthetic, narrowband, metallicity-sensitive CaHK magnitudes that mimic observations Pristine survey, a survey photometric metallicities Milky Way has been mapping more than 6500 deg 2 northern sky with Canada–France–Hawaii Telescope since 2015. These synthetic were for an absolute recalibration deeper photometry and, combined broadband information, and estimate over whole sky....