A5041020592- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Optical Systems and Laser Technology
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Calibration and Measurement Techniques
- Mechanics and Biomechanics Studies
- Molecular Spectroscopy and Structure
- High-pressure geophysics and materials
- Advanced optical system design
- Relativity and Gravitational Theory
- History and Developments in Astronomy
- Heat Transfer Mechanisms
- Astrophysics and Cosmic Phenomena
- Spectroscopy and Laser Applications
- Optical measurement and interference techniques
- Atmospheric Ozone and Climate
- Geophysics and Sensor Technology
- Optical Polarization and Ellipsometry
Observatoire de Paris
2014-2024
Université Paris Cité
2014-2024
Centre National de la Recherche Scientifique
2014-2024
Sorbonne Paris Cité
2016-2024
Sorbonne Université
2014-2024
Université Paris Sciences et Lettres
2016-2024
Laboratoire d’études spatiales et d’instrumentation en astrophysique
2015-2024
Janssen (France)
2012-2024
Max Planck Institute for Astronomy
2024
Max Planck Institute for Extraterrestrial Physics
2024
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...
We analyze deep near-IR adaptive optics imaging as well new proper motion data of the nuclear star cluster Milky Way. The surface density distribution faint stars peaks within 0.2" black hole candidate SgrA*. radial this stellar 'cusp' follows a power law exponent 1.3-1.4. K-band luminosity function overall (within 9" SgrA*) resembles that large scale, Galactic bulge, but shows an excess at K<14. find most massive early type distances 1-10" from SgrA* are located in two rotating and...
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...
By using the GRAVITY instrument with near-infrared (NIR) Very Large Telescope Interferometer (VLTI), structure of broad (emission-)line region (BLR) in active galactic nuclei (AGNs) can be spatially resolved, allowing central black hole (BH) mass to determined. This work reports new NIR VLTI/GRAVITY interferometric spectra for four type 1 AGNs (Mrk 509, PDS 456, Mrk 1239, and IC 4329A) resolved broad-line emission. Dynamical modelling data constrains BLR radius BH measurements our targets...
We describe a new type of coronagraph, based on the principle phase mask as proposed by Roddier and few years ago but using an original design found one us (D. R.), four‐quadrant binary (0, π) covering full field view at focal plane. The mutually destructive interferences coherent light from main source produce very efficient nulling. computed rejection rate this coronagraph appears to be high since, when perfectly aligned phase‐error free, it could in reduce total amount bright factor 108,...
This paper reports measurements of Sgr A* made with NACO in L' -band (3.80 um), Ks-band (2.12 um) and H-band (1.66 VISIR N-band (11.88 at the ESO VLT, as well XMM-Newton X-ray (2-10 keV) wavelengths. On 4 April, 2007, a very bright flare was observed from simultaneously L'-band No emission detected using VISIR. The resulting SED has blue slope (beta > 0 for nuL_nu ~ nu^beta, consistent nu^0.4) between 12 micron 3.8 micron. For first time our high quality data allow detailed comparison...
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...
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...
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...
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...
We present new near-infrared VLTI/GRAVITY interferometric spectra that spatially resolve the broad Br$\gamma$ emission line in nucleus of active galaxy IRAS 09149-6206. use these data to measure size region (BLR) and estimate mass central black hole. Using an improved phase calibration method reduces differential uncertainty 0.05 degree per baseline across spectrum, we detect a signal reaches maximum ~0.5 between continuum. This represents offset ~120 $\mu$as (0.14 pc) BLR centroid hot dust...
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...
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...
Context. The nearby and young β Pictoris system hosts a well resolved disk, directly imaged massive giant planet orbiting at ≃9 au, as an inner ≃2.7 which was recently detected through radial velocity (RV). As such, it offers several unique opportunities for detailed studies of planetary formation early evolution. Aims. We aim to further constrain the orbital physical properties b c using combination high contrast imaging, long base-line interferometry, RV data. also predict closest...
MICADO is the adaptive optics imaging camera for E-ELT. It has been designed and optimised to be mounted LGS-MCAO system MAORY, will provide diffraction limited over a wide (~1 arcmin) field of view. For initial operations, it can also used with its own simpler AO module that provides on-axis performance using natural guide stars. We discuss instrument's key capabilities expected performance, show how science drivers have shaped design. outline technical concept, from opto-mechanical design...
These protoplanetary disks in T Tauri stars play a central role star and planet formation. We spatially resolve at sub-au scales the innermost regions of sample Tauri's to better understand their morphology composition. extended our homogeneous data set 27 Herbig collected near-IR K-band observations 17 stars, spanning effective temperatures luminosities ranges ~4000-6000 K ~0.4-10 Lsun. focus on continuum emission develop semi-physical geometrical models fit interferometric search for...
This White Paper presents the scientific motivations for a multi-object spectrograph (MOS) on European Extremely Large Telescope (E-ELT). The MOS case draws all fields of contemporary astronomy, from extra-solar planets, to study halo Milky Way and its satellites, resolved stellar populations in nearby galaxies out observations earliest 'first-light' structures partially-reionised Universe. material presented here results thorough discussions within community over past four years, building...
Aims: We aim to spatially and spectrally resolve the Br-gamma hydrogen emission line with methods of interferometry in order examine kinematics gas region inner accretion disk a sample solar-like young stellar objects. The goal is identify trends categories among sources our discuss whether or not they can be tied different origin mechanisms associated T Tauri stars, chiefly most prominently magnetospheric accretion. Methods: observed seven stars for first time VLTI GRAVITY, recording...
The main objective of the COMPASS project is to provide a full scale end-to-end AO development platform, able address E-ELT and designed as free, open source numerical tool with long term maintenance plan. this platform based on integration software hardware relies an optimized implementation heterogeneous using GPUs accelerators. In paper, we present overall various work packages project, milestones be reached, results already obtained first output ongoing collaborations.