A5055923765- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Advanced optical system design
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Photonic and Optical Devices
- Particle Detector Development and Performance
- Optical Systems and Laser Technology
- Semiconductor Lasers and Optical Devices
- Molecular Spectroscopy and Structure
- Dark Matter and Cosmic Phenomena
- Advanced Measurement and Metrology Techniques
- Geophysics and Gravity Measurements
- Spectroscopy and Laser Applications
- Radio Astronomy Observations and Technology
- Photorefractive and Nonlinear Optics
- Advanced Fiber Optic Sensors
- Advanced Fiber Laser Technologies
- Atmospheric Ozone and Climate
Institut de Planétologie et d'Astrophysique de Grenoble
2015-2024
Centre National de la Recherche Scientifique
2015-2024
Université Grenoble Alpes
2015-2024
Max Planck Institute for Astronomy
2016-2024
University of Turku
2023
TU Dortmund University
2023
University of Łódź
2023
Niels Brock
2023
University of Copenhagen
2023
Main Astronomical Observatory
2023
The highly elliptical, 16-year-period orbit of the star S2 around massive black hole candidate Sgr A ✻ is a sensitive probe gravitational field in Galactic centre. Near pericentre at 120 AU ≈ 1400 Schwarzschild radii, has an orbital speed ≈7650 km s −1 , such that first-order effects Special and General Relativity have now become detectable with current capabilities. Over past 26 years, we monitored radial velocity motion on sky S2, mainly SINFONI NACO adaptive optics instruments ESO Very...
The star S2 orbiting the compact radio source Sgr A* is a precision probe of gravitational field around closest massive black hole (candidate). Over last 2.7 decades we have monitored star’s radial velocity and motion on sky, mainly with SINFONI NACO adaptive optics (AO) instruments ESO VLT, since 2017, four-telescope interferometric beam combiner instrument GRAVITY. In this Letter report first detection General Relativity (GR) Schwarzschild Precession (SP) in S2’s orbit. Owing to its highly...
We report the detection of continuous positional and polarization changes compact source SgrA* in high states ('flares') its variable near- infrared emission with near-infrared GRAVITY-Very Large Telescope Interferometer (VLTI) beam-combining instrument. In three prominent bright flares, position centroids exhibit clockwise looped motion on sky, scales typically 150 micro-arcseconds over a few tens minutes, corresponding to about 30% speed light. At same time, flares rotation angle,...
Context. PIONIER stands for Precision Integrated-Optics Near-infrared Imaging ExpeRiment. It combines four 1.8m Auxilliary Telescopes or 8m Unit of the Very Large Telescope Interferometer (ESO, Chile) using an integrated optics combiner. The instrument was at IPAG in December 2009 and commissioned Paranal Observatory October 2010. has provided scientific observations since November
We present a 0.16% precise and 0.27% accurate determination of R0, the distance to Galactic Center. Our measurement uses star S2 on its 16-year orbit around massive black hole Sgr A* that we followed astrometrically spectroscopically for 27 years. Since 2017, added near-infrared interferometry with VLTI beam combiner GRAVITY, yielding direct separation vector between an accuracy as good 20 micro-arcsec in best cases. passed pericenter highly eccentric May 2018, passage dense sampling...
The stars orbiting the compact radio source Sgr A* in Galactic Centre are precision probes of gravitational field around closest massive black hole. In addition to adaptive optics assisted astrometry (with NACO / VLT) and spectroscopy SINFONI VLT, NIRC2 Keck GNIRS Gemini) over three decades, since 2016/2017 we have obtained 30-100 mu-as with four-telescope interferometric beam combiner GRAVITY VLTI reaching a sensitivity mK = 20 when combining data from one night. We present simultaneous...
Tight relationships exist in the local universe between central stellar properties of galaxies and mass their supermassive black hole. These suggest holes co-evolve, with main regulation mechanism being energetic feedback from accretion onto hole during its quasar phase. A crucial question is how relationship evolves time; a key epoch to probe this at peaks star formation growth 8-12 billion years ago (redshifts 1-3). Here we report dynamical measurement luminous redshift 2, look back time...
To date, infrared interferometry at best achieved contrast ratios of a few times $10^{-4}$ on bright targets. GRAVITY, with its dual-field mode, is now capable high observations, enabling the direct observation exoplanets. We demonstrate technique HR8799, young planetary system composed four known giant used GRAVITY fringe tracker to lock fringes central star, and integrated off-axis HR8799e planet situated 390 mas from star. Data reduction included post-processing remove flux leaking star...
Context. It is now generally accepted that the near-infrared excess of Herbig AeBe stars originates in dust a circumstellar disk. Aims. The aims this article are to infer radial and vertical structure these disks at scales order one au, properties grains. Methods. program objects (51 total) were observed with H-band (1.6micron) PIONIER/VLTI interferometer. largest baselines allowed us resolve (at least partially) structures few tenths an au typical distances hundred parsecs. Dedicated...
Context. β Pictoris is arguably one of the most studied stellar systems outside our own. Some 30 yr observations have revealed a highly-structured circumstellar disk, with rings, belts, and giant planet: b. However very little known about how this system came into being. Aims. Our objective to estimate C/O ratio in atmosphere b obtain an dynamical mass planet, as well refine its orbital parameters using high-precision astrometry. Methods. We used GRAVITY instrument four 8.2 m telescopes Very...
We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. obtained spectra and 100 $\mu$as precision astrometry both b c in two epochs, as well spatially resolving hot inner disk around star. Rejecting unstable orbits, we found a nonzero eccentricity for $0.17 \pm 0.06$, near-circular orbit c, an orbital configuration that is consistent planets migrating into 2:1 mean motion resonance. Enforcing dynamical stability, 95% upper...
Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive planets with a small orbital period, whereas direct detection is orbiting at large distance from their host star. %, thus on long period. This dichotomy makes it difficult combine the techniques single target once. Simultaneous measurements made by offer possibility of determining mass luminosity method testing formation models. Here, we aim show how...
Infrared observations of Sgr A* probe the region close to event horizon black hole at Galactic center. These can constrain properties low-luminosity accretion as well that itself. The GRAVITY instrument ESO VLTI has recently detected continuous circular relativistic motion during infrared flares which been interpreted orbital near horizon. Here we analyze astrometric data from these flares, taking into account effects out-of-plane and shear material hole. We have developed a new code predict...
Aims. We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from astrometry another exoplanet. Methods. combined previous β Pictoris b with a new set observations GRAVITY interferometer. The orbital motion is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. inner planet, c, was also reobserved at separation 96 mas, confirming estimations. Results. From planet only, we (i) detect c (ii) constrain its 10.04 −3.10 +4.53 M Jup . If...
Photonics offer numerous functionalities that can be used to realize astrophotonic instruments. The most spectacular example date is the ESO Gravity instrument at Very Large Telescope in Chile. Integrated devices stand critical advantages for development, including extreme miniaturization, as well integration, superior thermal and mechanical stabilization owing small footprint, high replicability offering cost savings. Numerous technologies have been developed address shortcomings of...
With four companions at separations from 16 to 71 au, HR 8799 is a unique target for direct imaging, presenting an opportunity the comparative study of exoplanets with shared formation history. Combining new VLTI/GRAVITY observations obtained within ExoGRAVITY program archival data, we perform systematic atmospheric characterisation all planets. We explore different levels model flexibility understand temperature structure, chemistry and clouds each planet using both petitRADTRANS retrievals...
<i>Context. <i/>Recently, an increasing number of scientific publications making use images obtained with near-infrared long-baseline interferometry have been produced. The technique has reached, at last, a technical maturity level that opens new avenues for numerous astrophysical topics requiring milli-arc-second model-independent imaging. Very Large Telescope Interferometer (VLTI) will soon be equipped instruments able to combine between four and six telescopes.<i>Aims. <i/>In the...
Precise measurements of the S-stars orbiting SgrA* have set strong constraints on nature compact object at centre Milky Way. The presence a black hole in that region is well established, but its neighboring environment still an open debate. In respect, existence dark matter central may be detectable due to signatures orbits stars: main effect Newtonian precession which will affect overall pericentre shift S2, latter being target measurement GRAVITY instrument. exact this (e.g., stellar...
We study the time-variable linear polarisation of Sgr A* during a bright NIR flare observed with GRAVITY instrument on July 28, 2018. Motivated by time evolution both astrometric and polarimetric signatures, we interpret data in terms polarised emission compact region ('hotspot') orbiting black hole fixed, background magnetic field geometry. calculated grid general relativistic ray-tracing models, created mock observations simulating instrumental response, compared predicted quantities...
We report the time-resolved spectral analysis of a bright near-infrared and moderate X-ray flare Sgr A*. obtained light curves in $M$-, $K$-, $H$-bands mid- $2-8~\mathrm{keV}$ $2-70~\mathrm{keV}$ bands X-ray. The observed slope band is $\nu L_\nu\propto \nu^{0.5\pm0.2}$; L_\nu \propto \nu^{-0.7\pm0.5}$. tested synchrotron self-Compton (SSC) scenarios. brightness faintness, together with slopes, pose challenges for all models explored. rule out scenario which emission SSC. A one-zone model...
The Michigan Young Star Imager at CHARA (MYSTIC) is a K-band interferometric beam combining instrument funded by the U.S. National Science Foundation, designed primarily for imaging sub-au scale disk structures around nearby young stars and to probe planet formation process.Installed Array in July 2021, with baselines up 331 m, MYSTIC provides maximum angular resolution of λ∕2B ∼ 0.7 mas.The injects phase-corrected light from array into inexpensive, single-mode, polarization maintaining...
ABSTRACT The motion of S2, one the stars closest to Galactic Centre, has been measured accurately and used study compact object at centre Milky Way. It is commonly accepted that this a supermassive black hole, but nature its environment open discussion. Here, we investigate possibility dark matter in form an ultralight scalar field ‘cloud’ clusters around Sgr A*. We use available data for S2 perform Markov Chain Monte Carlo analysis find best-fit estimates cloud structure. Our results show...