Publications (38)
A powerful flare from Sgr A* confirms the synchrotron nature of the X-ray emission
G. Ponti, E. George, S. Scaringi +21
We present the first fully simultaneous fits to the NIR and X-ray spectral slope (and its evolution) during a very bright flare from Sgr A*, the supermassive black hole at the Milk…
Relative depolarization of the black hole photon ring in GRMHD models of Sgr A* and M87*
A. Jiménez-Rosales, J. Dexter, S. M. Ressler +15
Using general relativistic magnetohydrodynamic simulations of accreting black holes, we show that a suitable subtraction of the linear polarization per pixel from total intensity i…
First direct detection of an exoplanet by optical interferometry; Astrometry and K-band spectroscopy of HR8799 e
S. Lacour, M. Nowak, J. Wang +85
To date, infrared interferometry at best achieved contrast ratios of a few times on bright targets. GRAVITY, with its dual-field mode, is now capable of high contrast obs…
MOLsphere and pulsations of the Galactic Center's red supergiant GCIRS 7 from VLTI/GRAVITY
GRAVITY Collaboration, G. RodrÃguez-Coira, T. Paumard +55
GCIRS 7, the brightest star in the Galactic central parsec, formed Myr ago together with dozens of massive stars in a disk orbiting the central black-hole. It has been argu…
A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
R. Abuter, A. Amorim, M. Bauboeck +51
We present a 0.16% precise and 0.27% accurate determination of R0, the distance to the Galactic Center. Our measurement uses the star S2 on its 16-year orbit around the massive bla…
The GRAVITY Young Stellar Object survey IV. The CO overtone emission in 51 Oph at sub-au scales
GRAVITY Collaboration, M. Koutoulaki, R. Garcia Lopez +69
51 Oph is a Herbig Ae/Be star that exhibits strong near-infrared CO ro-vibrational emission at 2.3 micron, most likely originating in the innermost regions of a circumstellar disc.…
3D AMR simulations of G2 as an outflow
A. Ballone, M. Schartmann, A. Burkert +8
We study the evolution of G2 in a \textit{Compact Source Scenario}, where G2 is the outflow from a low-mass central star moving on the observed orbit. This is done through 3D AMR s…
Improved GRAVITY astrometric accuracy from modeling of optical aberrations
GRAVITY Collaboration, R. Abuter, A. Amorim +60
The GRAVITY instrument on the ESO VLTI pioneers the field of high-precision near-infrared interferometry by providing astrometry at the as level. Measurements at such…
Deep Images of the Galactic Center with GRAVITY
GRAVITY Collaboration, R. Abuter, N. Aimar +65
Stellar orbits at the Galactic Center provide a very clean probe of the gravitational potential of the supermassive black hole. They can be studied with unique precision, beyond th…
The Post-Pericenter Evolution of the Galactic Center Source G2
P. M. Plewa, S. Gillessen, O. Pfuhl +9
In early 2014 the fast-moving near-infrared source G2 reached its closest approach to the supermassive black hole Sgr A* in the Galactic Center. We report on the evolution of the i…
The G2+G2t complex as a fast and massive outflow?
A. Ballone, M. Schartmann, A. Burkert +8
Observations of the gas component of the cloud G2 in the Galactic Center have revealed its connection to a tail (G2t) lying on the same orbit. More recent studies indicate a connec…
Spectroscopic Detection of a Cusp of Late-type Stars around the Central Black Hole in the Milky Way
M. Habibi, S. Gillessen, O. Pfuhl +12
In a dynamically relaxed cluster around a massive black hole a dense stellar cusp of old stars is expected to form. Previous observations showed a relative paucity of red giant sta…
Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole
GRAVITY Collaboration, R. Abuter, A. Amorim +95
The highly elliptical, 16-year-period orbit of the star S2 around the massive black hole candidate Sgr A* is a sensitive probe of the gravitational field in the Galactic centre. Ne…
3D adaptive mesh refinement simulations of the gas cloud G2 born within the disks of young stars in the Galactic Center
M. Schartmann, A. Ballone, A. Burkert +8
The dusty, ionized gas cloud G2 is currently passing the massive black hole in the Galactic Center at a distance of roughly 2400 Schwarzschild radii. We explore the possibility of…
A measure of the size of the magnetospheric accretion region in TW Hydrae
R. Garcia Lopez, A. Natta, A. Caratti o Garatti +69
Stars form by accreting material from their surrounding disks. There is a consensus that matter flowing through the disk is channelled onto the stellar surface by the stellar magne…
A note on co-maximal graph of non-commutative rings
S. Akbari, M. Habibi, A. Majidinya +1
Let be a ring with unity. The graph is a graph with vertices as elements of , where two distinct vertices and are adjacent if and only if . Let $Î_…
The mass distribution in the Galactic Centre from interferometric astrometry of multiple stellar orbits
GRAVITY Collaboration, R. Abuter, N. Aimar +62
The stars orbiting the compact radio source Sgr A* in the Galactic Centre are precision probes of the gravitational field around the closest massive black hole. In addition to adap…
3D AMR hydrosimulations of a compact source scenario for the Galactic Centre cloud G2
A. Ballone, M. Schartmann, A. Burkert +8
The nature of the gaseous and dusty cloud G2 in the Galactic Centre is still under debate. We present three-dimensional hydrodynamical adaptive mesh refinement (AMR) simulations of…
The Flux Distribution of Sgr A*
The GRAVITY Collaboration, R. Abuter, A. Amorim +54
The Galactic Center black hole Sagittarius A* is a variable NIR source that exhibits bright flux excursions called flares. The low-flux density turnover of the flux distribution is…
Packing of elastic wires in spherical cavities
N. Stoop, J. Najafi, F. K. Wittel +2
We investigate the morphologies and maximum packing density of thin wires packed into spherical cavities. Using simulations and experiments, we find that ordered as well as disorde…
Flaremodel: An open-source Python package for one-zone numerical modelling of synchrotron sources
Y. Dallilar, S. von Fellenberg, M. Bauböck +13
Synchrotron processes, the radiative processes associated with the interaction of energetic charged particles with magnetic field, are of interest in many areas in astronomy, from…
Where intermediate-mass black holes could hide in the Galactic Centre: A full parameter study with the S2 orbit
The GRAVITY Collaboration, O. Straub, M. Bauböck +59
In the Milky Way the central massive black hole, SgrA*, coexists with a compact nuclear star cluster that contains a sub-parsec concentration of fast-moving young stars called S-st…
Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole
GRAVITY Collaboration, R. Abuter, A. Amorim +53
The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black hole (candidate). Over the last 2.7 decades we…
Sgr A* near-infrared flares from reconnection events in a magnetically arrested disc
J. Dexter, A. Tchekhovskoy, A. Jiménez-Rosales +14
Large-amplitude Sgr A* near-infrared flares result from energy injection into electrons near the black hole event horizon. Astrometry data show continuous rotation of the emission…
Constraining particle acceleration in Sgr A* with simultaneous GRAVITY, Spitzer, NuSTAR and Chandra observations
R. Abuter, A. Amorim, M. Bauböck +81
We report the time-resolved spectral analysis of a bright near-infrared and moderate X-ray flare of Sgr A*. We obtained light curves in the -, -, and -bands in the mid- an…
Twelve years of spectroscopic monitoring in the Galactic Center: the closest look at S-stars near the black hole
M. Habibi, S. Gillessen, F. Martins +11
We study the young S-stars within a distance of 0.04 pc from the supermassive black hole in the center of our Galaxy. Given how inhospitable the region is for star formation, their…
Optical Distortion in the NACO Imager
P. M. Plewa, S. Gillessen, M. Bauböck +11
In this research note, we present a set of distortion solutions that may be used to correct geometric optical distortion in images taken with the S13 camera of the NACO adaptive op…
Pinpointing the near-infrared location of Sgr A* by correcting optical distortion in the NACO imager
P. M. Plewa, S. Gillessen, F. Eisenhauer +8
Near-infrared observations of stellar orbits at the Galactic Center provide conclusive evidence for a massive black hole associated with the compact radio source Sgr A*. The astrom…
Detection of a drag force in G2's orbit: Measuring the density of the accretion flow onto Sgr A* at 1000 Schwarzschild radii
S. Gillessen, P. M. Plewa, F. Widmann +14
The Galactic Center black hole Sgr A* is the archetypical example of an underfed massive black hole. The extremely low accretion rate can be understood in radiatively inefficient a…
Detection of faint stars near SgrA* with GRAVITY
GRAVITY Collaboration, R. Abuter, A. Amorim +58
The spin of the supermassive black hole that resides at the Galactic Centre can in principle be measured by accurate measurements of the orbits of stars that are much closer to Sgr…
Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA*
GRAVITY Collaboration, R. Abuter, A. Amorim +57
We report the detection of continuous positional and polarization changes of the compact source SgrA* in high states ('flares') of its variable near- infrared emission with the nea…
Dynamically important magnetic fields near the event horizon of Sgr A*
GRAVITY Collaboration, A. Jiménez-Rosales, J. Dexter +53
We study the time-variable linear polarisation of Sgr A* during a bright NIR flare observed with the GRAVITY instrument on July 28, 2018. Motivated by the time evolution of both th…
A parameter survey of Sgr A* radiative models from GRMHD simulations with self-consistent electron heating
J. Dexter, A. Jiménez-Rosales, S. M. Ressler +13
The Galactic center black hole candidate Sgr A* is the best target for studies of low-luminosity accretion physics, including with near-infrared and submillimeter wavelength long b…
3D AMR simulations of the evolution of the diffuse gas cloud G2 in the Galactic Centre
M. Schartmann, A. Ballone, A. Burkert +8
With the help of 3D AMR hydrodynamical simulations we aim at understanding G2's nature, recent evolution and fate in the coming years. By exploring the possible parameter space of…
Using the motion of S2 to constrain scalar clouds around SgrA*
GRAVITY Collaboration, A. Foschi, R. Abuter +67
The motion of S2, one of the stars closest to the Galactic Centre, has been measured accurately and used to study the compact object at the centre of the Milky Way. It is commonly…
Valence-shell single photoionization of Chlorine-like K ions: Experiment and Theory
G. A. Alna'Washi, M. Lu, M. Habibi +6
The absolute single photoionization cross-section was measured for Cl-like K over the photon energy range from 44.2 - 69.7 eV at a constant energy resolution of 0.045 eV. Th…
Modeling the orbital motion of Sgr A*'s near-infrared flares
The GRAVITY Collaboration, M. Bauböck, J. Dexter +53
Infrared observations of Sgr A* probe the region close to the event horizon of the black hole at the Galactic center. These observations can constrain the properties of low-luminos…
Test of Einstein equivalence principle near the Galactic center supermassive black hole
A. Amorim, M. Bauböck, J. P. Berger +49
During its orbit around the four million solar mass black hole Sagittarius A* the star S2 experiences significant changes in gravitational potential. We use this change of potentia…