Observational Cosmology

SPIRAL GALAXY PAIR NGC 4302 AND NGC 4298. (Image: hubblesite.org)

Members of this research group are:

Thomas Greve, Professor
Georgios Magdis, Associate Professor
Allan Hornstrup, Head of Astrophysics and Atmospheric Physics
Desiree Della Monica Ferreira, Senior Researcher
Lijie Liu, Postdoc
Minju Lee, Postdoc
Steven Richard Gillman, Postdoc
Bitten Gullberg, Postdoc
Aswin Payyoor Vijayan, Postdoc
Shuowen Jin, Postdoc
Malte Brinch, PhD student
Dazhi Zhou, PhD student
David Blanquez Sese, PhD student
Iris Jermann, PhD student

Our research and instrument development related to observational cosmology covers a broad range of topics. From the cosmic microwavebackground and large-scale structure, to the epoch of reionization, and the formation and evolution of galaxies across cosmic time.

The Observational Cosmology Group at DTU Space is dedicated to frontier-research that expands our cosmological horizon. We aim to understand the emergence of cosmic structures, including the physical processes that govern the  the birth, life, and death of galaxies, through observations with the prime telescopes of the next decade (ALMA, JWST, Euclid, E-ELT, HST) as well as through theory and numerical simulations. The group is involved in a number of observational surveys, utilizing multiple instruments and telescopes. To analyse the data the group develops both theoretical models and numerical simulations.

Our research themes include:

First galaxies -  What did the first galaxies look like? When and how did they form?  These are some of the most pressing questions in astrophysics today. Answering them is an observationally challenging task, which involves detecting the faintest sources at the edge of the observable Universe.  The most distant galaxy currently known is seen at an epoch where the Universe was only 400 million years old, 3% of its current age.

Galaxy evolution - Galaxies evolve through both internal and external processes, which lead them to have different characteristics. Some galaxies undergo a burst  of star-formation, others are quiescent. Galaxies are also impacted by their  environment. Some galaxies are isolated, some assemble together in clusters. Galaxy clusters are rich in gas and star-formation in the early universe, while becoming quiescent systems bound by massive dark matter halos at the present time. The interplay between these processes determine how the galaxies and galaxy clusters mature with cosmic time. At DTU Space we try to shed new light on this complex interplay through both observations and simulations.

The interstellar medium - Stars form in dense condensations of gas and dust in the interstellar medium. The interstellar medium is, therefore, pivotal to understanding galaxies, and determining its physical properties (e.g., gas temperatures and pressures), and how they vary from one galaxy to another, is an important part of our research.

DAWN - DTU Space hosts, together with the Niels Bohr Institute, the Cosmic Dawn Center (DAWN), an international frontier-research centre supported by the Danish National Research Foundation, committed to uncovering how and when the first galaxies, stars and black holes formed.  To this end, DTU Space and DAWN are involved in a number of observational programs on the JWST, which will provide unprecedented deep images of some of the very first galaxies. DTU Space has provided hardware to the MIRI instrument onboard JWST, and is part of the MIRI instrument team, where it has played an important role in testing and calibrating the MIRI data reduction pipeline.

The DTU Space and DAWN are also involved in Euclid, an upcoming ESA mission which will provide extremely wide and deep near-IR imaging of key cosmological fields. Supplementing this effort, DTU Space is leading an effort on the Greenland Telescope to survey at the NEP Euclid Deep Field millimeter wavelengths.

DTU Space A+A has several decades heritage in doing research in observational cosmology. Scientists from A+A were behind the early attempts to determine the Hubble constant using SNIa’s, which later was adopted by other groups to discover the acceleration of the expanding universe. A+A scientist have been using observations of clusters of galaxies both using X-rays and optical light to determine cosmological parameters.

Planck - A+A also participated in ESA’s Planck mission; providing the mirrors to the telescope of the observatory, and took part in analyzing the unique data from Planck. Special focus was given to extract polarization information from the Planck data.