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Centro de Astrofísica da Universidade do Porto
The Lyman alpha cosmic line

Daniel Kunth
Institut d'Astrophysique de Paris

The Lyman alpha is a cosmic recombination line in the sense that it occurs from the most atomic abundant element of the universe hence is potentially very bright. Therefore it allows the discovery and study of distant galaxies at redshift as large a 8 and potentially 10.
However its transfer in the ISM is complex due to the resonant nature of this line that interplays with the dust, the HI and is affected by the many parameters of the star formation event and that of the host galaxy. Our studies of local galaxies, performed with the HST, show this complexity. One of the major results of our HST imaging studies has been to reveal large extended Lyman alpha haloes much larger than that of H alpha, confirming the role of resonant scattering processes in the transfer of the Lyman photons. These studies have allowed us to consider the evolution of the Lyman alpha escape as a function of the cosmic time. We find evolution. We also ask the question whether dwarf galaxies are able to re-ionize the Universe at z around 6.

17 May 2013, 13:30

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Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

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