Binary system characterization with a fibered non-redundant interferometer for high dynamic range imaging
My work has been carried out in the context of imaging at high angular resolution and high dynamic range, and in particular on the development of the instrument called FIRST, Fibered Imager foR a Single Telescope. Its principle relies on the novel technique of pupil remapping, combining aperture masking and spatial filtering of the wavefront thanks to single-mode fibers. The purpose of my thesis was to mount FIRST on a telescope, improve its performances and develop a pipeline for data reduction and analysis. First light of the instrument has been obtained in July 2010 on the 3-m Shane telescope at Lick Observatory. Afterwards, I have been working on different aspects of the optical and mechanical design, in order to improve its performances during observations. We have then conducted an observation campaign spread out over several runs between July 2011 and December 2012. Primary targets were binary systems, which are ideal objects to assess the resolving power and the dynamic range of the instrument. For that purpose, I have developed a data reduction pipeline, allowing to derive interferometric observables from the fringe images and performing a fit of a binary model. I have thus reduced part of the large amount of data acquired at Lick Observatory, and in particular the data taken on the binary system Capella. The results show that the companion is detected, which lies at a separation on the order of the diffraction limit of the telescope. Moreover, our data provide an unprecedented measurement of the spectral flux ratio at visible wavelengths. Stellar atmospheric models have been fitted to this spectrum and demonstrate that such data provide valuable information to characterize a binary system, and in particular to constrain the effective temperatures of the two components. Finally, the success of the observations conducted at Lick Observatory has led us to initiate a collaboration with the SCExAO team from the Subaru telescope. FIRST has therefore been integrated to their optical bench and first light on the Subaru telescope has been achieved on July 25, 2013. To conclude, the results I have obtained validate the concept of pupil remapping on-sky and demonstrate that this technique allows to restore the capabilities of a telescope at the diffraction limit and at visible wavelengths. Although the sensitivity of FIRST is still limited, these results are highly promising regarding observations to come at the Subaru telescope and more generally regarding future developments based on this technique, in particular in the context of exoplanet detection and characterization.