The centre for astrophysics and gravitation (CENTRA) [1] is a member of the GRAVITY+ consortium [2]. Within the scope of our contribution to GRAVITY+ we have a  PhD position open starting Fall 2022 on the use of Adaptive Optics to enhance the performance of this instrument when installed at the VLTI.

Context 

GRAVITY+ will open up the extragalactic sky for milliarcsecond-resolution interferometric imaging, and give access to targets as faint as K = 22 mag [1,2]. GRAVITY+ will measure the black hole masses of active galactic nuclei across cosmic time and obtain high-quality exoplanet spectra and orbits.

GRAVITY+ is a significant upgrade of the Very Large Telescope Interferometer (VLTI) infrastructure and its GRAVITY instrument. In particular, further to UT4, the three remaining UTs will be equipped with laser guide stars and corresponding wavefront sensors and deformable mirrors.

The instrument development is progressing in a phased approach with planned delivery in 2025.

Work to be carried out

We are particularly interested in the following topics:

• Data-driven approaches to identify and predict piston to enhance fringe-tracking capabilities on which an interferometer’s performance is highly dependent. Various effects will be analysed including delay-line, telescope and atmospheric and photon-counting sensing regimes.
• The LGS mode of GRAVITY+ AO will dramatically increase the amount the extra galactic targets to be addressed by its client instruments. The main error term being the cone effect, we propose to investigate novel approaches based on prediction and tomography to better reconstruct the cylinder of turbulence seen by the science target.
• Robust control approaches that sustain acceptable levels of performance in the presence of non-stationary, varying observing conditions. One optimization criterion would be the maximization of the short exposure performance or the minimization of the flux drop events that lead to the loss of fringe tracking capabilities. This work could include the use of machine learning in the control approach.

The thesis involves several stages of theory, analytical developments, simulation studies and hands-on system calibration, telemetry acquisition and processing. The candidate will be involved in the on-sky commissioning of Gravity+ (planned for 2024).

Host Laboratory

The PhD will take place at the University of Porto, Faculty of Engineering where the PhD candidate will develop his/her work in a rich environment with access to state-of-the-art computing facilities and a knowledge base provided by the AO group. A period of 1 year (TBD) at ESO will be included. Close interaction with the GRAVITY+ consortium and ESO is expected.

Funding

Partial funding is provided by CENTRA following the national regulations for PhD grants set forth here.

Application           

In addition to applying through ESO recruitment portal, the Applicant should email (single pdf file)

• a curriculum vitae, including eventual list of publications;
• the contact details of up to three reference persons (no need for the reference letters at this stage);
• a short research statement describing past achievements and future projects

to Carlos Correia (carlos.correia@fe.up.pt), Paulo Garcia (pgarcia@fe.up.pt) and Sylvain Oberti.  The University of Porto and its partners are actively committed to equal opportunity in employment.

Candidates

Candidates with an excellent record in astronomy, applied physics, optics, mathematics, engineering with strong signal processing and programming skills are encouraged to apply.
                                        

Supervisor:  Sylvain Oberti