H2 in the Universe: Contrasting Theory and Observations
Astrophysics, Oxford University, Keble Road, Oxford, OX1 3RH, UK
2 Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11, 0QX, UK
Molecular hydrogen, H2, is the most abundant molecule in the Universe, regulating various processes in diverse astrophysical environments. With the advent of the Infrared Space Observatory (ISO) and the Spitzer Space Telescope (SST) we have been able to detect extragalactic H2 line emission opening up new avenues of exploring the physics of the interstellar medium (ISM) near and far. We review the role of such H2 emission line detections in our understanding of the physical mechanisms responsible for its excitation and the differences among different galaxy types. We discuss possibilities of detecting H2 from distant objects in the Universe thanks to the enhanced sensitivity of the SPICA/SAFARI instrument. Finally, we evaluate the role of H2 in the cosmological context as we contrast theory and observations.
Key words: Galaxies: formation / Galaxies: starbursts / Missions: SPICA
© Owned by the authors, published by EDP Sciences, 2009