NOVA Network 1

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hubble-ultra-deep-field

An estimated 10.000 galaxies are visible in this ultra deep field observed by the Hubble space telescope. The observation has been made in a small region of the constellation Fornax, where a low density of foreground stars allows Hubble to see the very faint objects in the extreme distance. The age of the galaxies in the image span almost the entire lifetime of the universe; the light of the most distance ones has taken 13.2 billion years to reach us. Image courtesy NASA / ESA / STScI.

Network 1: Formation and evolution of galaxies: from high redshift to the present

The research within Network 1 focuses on the evolution of the Universe and its constituents, with particular emphasis on the formation and evolution of galaxies, from high redshift to the present. The research can be split in themes associated to (1) the young universe and the earliest galaxies; (2) the physics of galaxy evolution, and (3) the local Universe and its fossil record.

Recent results include significant advances in the study of the dark matter distribution using weak gravitational lensing. For example, the final results from the CFHT Legacy Survey are in slight tension with measurements from Planck but in agreement with cluster abundance studies. Moreover the first results from the KiloDegree Survey have demonstrated its potential as a competitive probe for cosmology. Closer to home, the kinematics of stars in dwarf galaxies around the Milky Way have been used to constrain the distribution of dark matter in these systems. It has been found that the slopes of their dark halo density profiles at the half light radii, which have been measured for the first time in a model independent fashion, are consistent with cosmological expectations. On the other hand, the stellar content of these dwarf galaxies has been found to depict interesting differences in the populations of Carbon rich stars at low metallicities compared to the Milky Way, yielding new insights on the first populations of stars and the chemical enrichment in the early Universe.

Using a more traditional approach to study the early Universe, deep observations have led to the discovery of remarkably massive galaxies in the first billion years of cosmic time. These galaxies are likely host of the first generations of stars ever formed as is apparent from the brightest galaxy discovered to date in the early Universe. Significant progress has been made in measuring the luminosity distribution of galaxies at these epochs, which is crucial to constrain the origin of reionization, which is studied directly using LOFAR. State-of-the-art cosmological simulations are essential to interpret the wide range of observational results. EAGLE, a large sophisticated cosmological simulation of the formation of galaxies across cosmic time, is able to produce systems that match basic observed properties of galaxies, such as size and masses, thanks to better implementations of feedback processes. Such processes have also been studied in detail using a range of instruments. For example, observations of molecular gas in colliding galaxies have demonstrated the importance of mechanical heating, whereas high-resolution VLBI and ALMA observations revealed that radio plasma jets ejected by a supermassive black hole, clear cold gas from galaxies at velocities over 1000 km/s.

These studies have benefited from the instruments that have been developed by, or received contributions from NOVA over the years, such as LOFAR, OmegaCam on the VST, MIDI, X-Shooter, MUSE, ALMA and APEX. In the coming years  significant advances are expected from MUSE, as well as from space missions such as Gaia, which was launched in 2013, and JWST which is scheduled for launch in 2018.

 

Network 1 members:

Prof. dr. A. Helmi (chair) RUG
Prof. dr. P.D. Barthel RUG
Dr. R.J. Bouwens UL
Prof. dr. B. Brandl UL
Dr. J. Brinchmann UL
Dr. A.G.A Brown (nw1 & nw2) UL
Prof. dr. K.I. Caputi RUG
Dr. P. Dayal RUG
Prof. dr. M. Franx UL
Dr. M. Haverkorn (nw1 & nw2) RU
Dr. J.A. Hodge UL
Dr. H. Hoekstra UL
Prof. dr. L.V.E. Koopmans RUG
Prof. dr. K.H. Kuijken UL
Dr. S. Larsen RU
Dr. J.P. McKean RUG
Prof.dr. R.F. Peletier RUG
Dr. E.M. Rossi (nw1 & nw3) UL
Prof. dr. H.J.A. Röttgering UL
Prof. dr. J. Schaye UL
Prof. dr. E. Tolstoy RUG
Prof. dr. S.C. Trager RUG
Prof. dr. Valentijn RUG
Prof. dr. E.A. Verheijen RUG
Prof. dr. van der Weygaert RUG
Prof. dr. P. van der Werf UL
Prof. dr. S. Zaroubi RUG