Thesis

Adaptive Optics PSF estimation for the MUSE integral field spectrograph

• Call:

  IDPASC Portugal - PHD Programme 2017

• Academic Year:

  2017 / 2018

• Domain:

  Astrophysics

• Supervisor:

  Paulo Garcia

• Co-Supervisor:

  Carlos M Correia

• Institution:

  Universidade do Porto

• Host Institution:

  CENTRA

• Abstract:

  Adaptive Optics (AO) corrects in real time the aberrations introduced by the atmosphere when observing astrophysical targets with ground-based telescopes. High quality correction of on-axis targets is now routine. AO faces many challenges; some of them are the uniformity and quality of the correction outside the axis and on large fields. This is measured via the point spread function (PSF) of the system, i.e. the “image” of an unresolved object such as a star. Integral field spectroscopy is an observational technique that delivers for each spatial pixel a spectrum. Therefore the imaged field is integrally sampled spectrally. This technique is critical for the study of crowded regions and of objects such as galaxies, jets/outflows and compact clusters. In many situations the PSF is not known because there are not point sources in the field and the adaptive optics telemetry is used to estimate it. The PSF can then be used for deconvolving the data obtaining finer detail. The European Southern Observatory hosts the most advanced integral field spectrograph – MUSE. The instrument spectra are in the visible wavelength range. Currently MUSE is operating in seeing limited conditions but in 2016 the Adaptive Optics Facility (AOF) will be available, allowing ground layer AO correction in a large 1 arcminute field-of-view. The first goal of the thesis is to apply algorithms developed in-house to the AOF telemetry for the estimation of PSF in ground layer AO mode. The quality of the PSF estimation will be characterised. Astrophysical exploitation of this mode by studying for young stars will be also possible. The second phase of the AOF is the delivery of laser tomographic AO. By combining the tomographic sampling by the four lasers of the turbulent volume above the telescope, a very high quality correction is possible. MUSE is foreseen to operate in this mode with a high angular sampling (and corresponding smaller field of view – the so called Narrow Field Mode – 7.5 arcseconds field of view). The second goal of the thesis is an intermediate step towards the laser tomographic AO mode referred above and aims at PSF estimation using the telemetry of the off-axis laser tomographic system. The third goal of the thesis is the application and fine-tuning of the previous algorithm to the AOF laser tomographic system. As for the ground layer AO, the quality of the PSF estimation algorithm will be characterised with on-sky data and astrophysical exploitation will be possible. At the end of the thesis the candidate will have a unique profile in data analysis for integral field adaptive optics and astrophysical exploitation of MUSE. Profile: Student with strong interest in astrophysics, optics/propagation, mathematical modelling, statistical physics, numerical simulations, data/signal processing. The work will accompany developments within the OPTICON framework and similar activities at LAM – Laboratoire d'Astrophysique de Marseille; availability of potential candidates to spend time in Marseille is required. References: Bacon et al, “MUSE Commissioning”, The Messenger, vol. 157, p. 13, http://cdsads.u-strasbg.fr/cgi-bin/nph-data_query?bibcode=2014Msngr.157...13B Gilles, Correia et al, Simulation model based approach for long exposure atmospheric point