Thomas Ott
A5090479752- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Pulsars and Gravitational Waves Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Optical Systems and Laser Technology
- Gamma-ray bursts and supernovae
- Neural Networks and Applications
- Mechanics and Biomechanics Studies
- Advanced Measurement and Metrology Techniques
- Advanced optical system design
- Geographic Information Systems Studies
- Nonlinear Dynamics and Pattern Formation
- High-pressure geophysics and materials
- Cross-Border Cooperation and Integration
- Neural Networks Stability and Synchronization
- Neural dynamics and brain function
- Calibration and Measurement Techniques
- Heat Transfer Mechanisms
- Urbanization and City Planning
Max Planck Institute for Extraterrestrial Physics
2015-2024
Space Telescope European Coordinating Facility
2024
Space Telescope Science Institute
2024
Max Planck Institute for Astrophysics
2024
Institute of Astronomy and Astrophysics, Academia Sinica
2024
ZHAW Zurich University of Applied Sciences
2014-2023
Hensoldt (Germany)
2022-2023
Medical University of Graz
2022
Max Planck Society
2008-2021
Max Planck Innovation
2019-2021
We present the results of 16 years monitoring stellar orbits around massive black hole in center Milky Way using high resolution NIR techniques. This work refines our previous analysis mainly by greatly improving definition coordinate system, which reaches a long-term astrometric accuracy 300 microarcsecond, and investigating detail individual systematic error contributions. The combination long time baseline excellent adaptive optics data allow us to determine 28 stars, including star S2,...
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 report on 75 mas resolution, near-IR imaging spectroscopy within the central 30 lt-days of Galactic center, taken with new adaptive optics-assisted integral-field spectrometer SINFONI ESO VLT. To a limiting magnitude K ~ 16, 9 10 stars in 04, and 13 17 out to 07 from black hole have spectral properties B0-B9 main-sequence stars. Based 2.1127 μm He I line width, all brighter early-type normal rotation velocities, similar solar neighborhood combine radial velocities SHARP/NACO astrometry...
We present Hα integral field spectroscopy of well-resolved, UV/optically selected z ∼ 2 star-forming galaxies as part the SINS survey with SINFONI on ESO VLT. Our laser guide star adaptive optics and good seeing data show presence turbulent rotating outer rings/disks, plus central bulge/inner disk components, whose mass fractions relative to total dynamical appear scale [N II]/Hα flux ratio formation age. propose that buildup disks bulges massive at can be driven by early secular evolution...
We report the definite spectroscopic identification of ≃40 OB supergiants, giants, and main-sequence stars in central parsec Galaxy. Detection their absorption lines has become possible with high spatial spectral resolution sensitivity adaptive optics integral field spectrometer SPIFFI/SINFONI on ESO VLT. Several these appear to be helium- nitrogen-rich. Almost all ≃80 massive now known (central arcsecond excluded) reside one two somewhat thick (⟨ /R⟩ ≃ 0.14) rotating disks. These stellar...
Using 25 years of data from uninterrupted monitoring stellar orbits in the Galactic Center, we present an update main results this unique set: A measurement mass and distance to SgrA*. Our progress is not only due eight year increase time base, but also improved definition coordinate system. The star S2 continues yield best constraints on SgrA*; statistical errors 0.13 x 10^6 M_sun 0.12 kpc have halved compared previous study. orbit fit robust does need any prior information. system priors,...
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...
Two recent papers (Ghez et al. 2008; Gillessen 2009) have estimated the mass of and distance to massive black hole (MBH) in center Milky Way using stellar orbits. The two astrometric data sets are independent yielded consistent results, even though measured positions do not match when simply overplotting sets. In this Letter, we show that can be brought excellent agreement with each other allow for a small offset definition reference frame required offsets coordinates velocities origin...
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,...
We present new observations of the nuclear star cluster in central parsec Galaxy with adaptive optics assisted, integral field spectrograph SINFONI on ESO/VLT. Our work allows spectroscopic detection early- and late-type stars to mK ⩾ 16, more than 2 mag deeper our previous data sets. result a total sample 177 bona fide early-type stars. find that most these Wolf Rayet (WR), O-, B-stars reside two strongly warped disks between 08 12'' from Sgr A*, as well compact concentration (the S-star...
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...
We derive the extinction curve towards Galactic Center from 1 to 19 micron. use hydrogen emission lines of minispiral observed by ISO-SWS and SINFONI. The free flux reference is 2 cm continuum VLA. Towards inner 14" * 20" we find an A(2.166 micron)=2.62 +/- 0.11, with a power-law slope alpha=-2.11 0.06 shortward 2.8 micron, consistent average near infrared recent literature. At longer wavelengths, however, that grayer than it not possible fit dust model consisting pure carbonaceous silicate...
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...
The GRAVITY instrument on the ESO VLTI pioneers field of high-precision near-infrared interferometry by providing astrometry at $10 - 100\,\mu$as level. Measurements such high precision crucially depend control systematic effects. Here, we investigate how aberrations introduced small optical imperfections along path from telescope to detector affect astrometry. We develop an analytical model that describes impact measurement complex visibilities. Our formalism accounts for pupil-plane and...
We present new astrometric and polarimetric observations of flares from Sgr A* obtained with GRAVITY, the near-infrared interferometer at ESO's Very Large Telescope Interferometer (VLTI), bringing total sample well-covered to four ones six, where we have for two good coverage in both domains. All show clockwise motion plane sky a period around an hour, polarization vector rotates by one full loop same time. Given apparent similarities flares, common fit, taking into account absence strong...
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 report a new analysis of the stellar dynamics in Galactic Centre, based on improved sky and line-of-sight velocities for more than 100 stars central few arcseconds from black hole candidate SgrA*. The main results are as follows.
We present proper motions for $>$40 stars at projected distances $\leq1.2''$ from Sagittarius A* (Sgr A*). find evidence on a $\geq2σ$ level radial anisotropy of the cluster within $1''$ Sgr A*. no stationary source or variable position confirm/find accelerated motion 6 stars, with 4 having passed pericenter their orbits during observed time span. calculated/constrained orbital parameters these stars. All have moderate to high eccentricities. discuss possible bias in detecting...
We report new astrometric and spectroscopic observations of the star S2 orbiting massive black hole in Galactic center that were taken at ESO VLT with adaptive optics-assisted, near-IR camera NAOS/CONICA integral field spectrometer SPIFFI. use these data to determine all orbital parameters high precision, including Sun-Galactic distance, which is a key parameter for calibrating stellar standard candles an important rung extragalactic distance ladder. Our deduced value R0 = 7.94 ± 0.42 kpc...
We discuss constraints on the properties and nature of dark mass concentration at core Milky Way. present 0.15-arcsec astrometric K-band maps in five epochs beween 1992 1996. From these we derive imposed stellar proper motions within 3 arcsec compact radio source Sgr A* whose infrared counterpart may have been detected, for first time, a deep image 1996 June. also report λ/Δλ ~ 35 speckle spectroscopy show that several (infrared) cluster members are likely early-type stars 15 to 20 M⊙. All...