GRAVITY+

GRAVITY and the VLTI have transformed optical interferometry with groundbreaking results on the Galactic Center, active galactic nuclei, and exoplanets.

The GRAVITY+ project upgrades GRAVITY and the VLTI in order to open up the extragalactic sky for milliarcsecond-resolution interferometric imaging, and will give access to targets as faint as K = 22 mag. GRAVITY+ measures the black hole masses of active galactic nuclei across cosmic time, and obtains high-quality exoplanet spectra and orbits.

GRAVITY+ provides wide-field off-axis fringe tracking, and improved sensitivity and contrast from new natural guide star and laser guide star adaptive optics for all VLT 8 m unit telescopes. The GRAVITY+ upgrades are implemented incrementally, keeping the impact on operation to a minimum. They add new, globally unique science capabilities with every step. As an infrastructure upgrade of the VLTI, GRAVITY+ serves all present and future VLTI instruments along with their communities.

Following a summer 2020 recommendation by ESO’s STC, GRAVITY+ went through a Phase A process, which was successfully concluded in summer 2021, in order to become ESO’s next VLT facility instrument. GRAVITY+ is built by a consortium including MPE, INSU/CNRS, University of Cologne, MPIA, CENTRA, University of Southampton, and the associated partners KU Leuven, University College Dublin, and Universidad Autonoma de Mexico, in close collaboration with ESO and supported by the Max Planck Foundation. Wide field fringe tracking capability including new delay lines, new state of the art adaptive optics, and Laser Guide Stars for UT1-3 are in operation. The GRAVITY beam combiner instrument will be upgraded in 2027 with a high resolution grism and new fiber couplers.

Illustration of four telescopes on a platform, equipped with laser guide stars, a modern adaptive optics system, vibration control and a grism upgrade. — This picture shows the upgrade of GRAVITY and the VLTI to GRAVITY+ for faint-science, all-sky, high-contrast, milliarcsecond interferometric imaging. The key elements are improved instrument throughput and vibration control, wide-field off-axis fringe tracking, state-of-the-art adaptive optics, and laser guide stars for all telescopes.

This picture shows the upgrade of GRAVITY and the VLTI to GRAVITY+ for faint-science, all-sky, high-contrast, milliarcsecond interferometric imaging. The key elements are improved instrument throughput and vibration control, wide-field off-axis fringe tracking, state-of-the-art adaptive optics, and laser guide stars for all telescopes.

See this link for an animation visualizing GRAVITY+.

Science cases for GRAVITY+ include:

The Galactic Center
Galaxy AGN coevolution and the masses of supermassive Black Holes, including super-Eddington accretion, tidal disruption events, and supermassive Black Hole binaries
Characterization of exoplanets
Young suns and their planet-forming disks
Microlenses
Massive stars
Intermediate-mass black holes

More information on the GRAVITY+ concept and science can be found in this document, which is based on the GRAVITY+ proposal to ESO, and in two articles in The Messenger describing GRAVITY+ and its commissioned wide field mode., and the First light paper for the Gravity+ adaptive optics.

Events

GRAVITY+ Phase A Review, July 9 to 12, 2021
EAS lunch session "Taking infrared interferometry to the next level with GRAVITY+", June 29, 2021
GRAVITY+ community workshop, February 24 to 25, 2021
Observing the Universe in Motion: 5 Years of GRAVITY, October 23 to 29, 2022
GRAVITY+ at Higher Spectral Resolution, September 12 to 13, 2024
Horizons for Optical Long Baseline Interferometry, January 27 to 30, 2025

Publications

Publications from GRAVITY and GRAVITY+ with MPE involvement can be found here:

Follow GRAVITY+ on twitter!

Code of Conduct

The GRAVITY + collaboration is committed to creating a safe and professional work environment free of all forms of discrimination, harassment and retaliation, where diversity and inclusion are valued and where everyone is entitled to be treated with courtesy and respect. Consequently, the GRAVITY+ collaboration will not tolerate any form of harassment. We follow the Code of Conduct for the Max Planck Society.

Our core values are

• We treat each other with respect.
• We act honestly, ethically and with integrity.
• We communicate transparently and respectfully both internally and externally.

We expect everyone in the GRAVITY+ collaboration to reflect the Core Values of the MPG in their actions.

Any of the GRAVITY+ Co-Is^* can be contacted when concerns arise from a potential violation of Code of Conduct. We will treat any information as confidential, unless we are required by our institutions to report it. See also webpages of the GRAVITY+ partner institutes for additional contact points (for members of MPE: https://intranet.mpe.mpg.de/683879/konflikt-management).

^*GRAVITY+ CoIs: Paulo Garcia, Sebastian Hönig, Laura Kreidberg, Jean-Baptiste Le Bouquin, Thibaut Paumard, Christian Straubmeier, Frank Eisenhauer (PI)