Title: Constraining the spectral energy distribution of ionizing photons emitted from stars in galaxies at the epoch of cosmic reionization
Cosmic reionization corresponds to the period in the history of the Universe during which the predominantly neutral intergalactic medium was ionised by the emergence of the first luminous sources.
Young stars in primeval galaxies may be the sources of reionization, if the ionising radiation, called Lyman continuum (LyC), that they produce can escape their interstellar medium to reach the intergalactic medium and contribute to its reionization. The spectral energy distribution of the stellar continuum has not been studied in detailed so far, given the lack of observational constraints. But recent observations from our team have changed the paradigme: we have discovered a class of galaxies that are transparent to their own ionizing radiation (Izotov 16a,b,18a,b). For the first time, this part of the spectrum of galaxies can now be confronted to theoretical expectations. This will be the main topic of the PhD project.
The student will work at the interface between models and observations: she/he will confront the existent models of synthetic spectra of galaxies --including the effect of massive stars, stellar rotation, interacting binary systems-- with actual and forthcoming observations; she/he will participate actively to the forthcoming observational campaigns to detect Lyman continuum from galaxies with the UV satellites Astrosat and HST, in complement to VLT-MUSE GTO data, and she/he may also explore archival data from the satellite EUVE to study the spectral energy distribution of the ionizing radiation emitted from individual stars and binary systems.
The PhD project will start in fall 2018, for 4 years, under supervision of Prof. Anne Verhamme from the University of Geneva, in co-direction with Prof. D. Schaerer from the University of Geneva.
The Geneva Observatory and the associated Laboratory of Astrophysics of the Swiss Federal Institute of Technology in Lausanne (EPFL) carry out observational, interpretative and theoretical research in the fields of extra-solar planets, stellar physics, high energy astrophysics, galaxy evolution and dynamics, and observational cosmology.
Qualified candidates are encouraged to send their application including a CV, description of research experience and interests, Master grades, and contact information of three references preferably via email to the above address. Applications received by 15th of June, 2018 will receive consideration. Informal enquiries with Anne Verhamme (anne.verhamme at unige.ch) are welcome.
For information on the research group visit http://www.unige.ch/sciences/astro/reionization/en/
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