Science with SKA?

SKA will give astronomers insight into the formation and evolution of the first stars and galaxies after the Big Bang, the role of cosmic magnetism, the nature of gravity and possibly life beyond Earth.

Five key science projects have been selected:

Extreme tests of general relativity with pulsars and black holes

For almost ninety years, Einstein’s Theory of General Relativity has precisely predicated the outcome of every experiment made to test it. Most of these tests, including the most stringent ones, have been carried out using astronomical measurements. By using pulsars as cosmic gravitational wave detectors, or timing pulsars found orbiting black holes, astronomers will be able to examine the limits of General Relativity such as the behaviour of space and time in regions of extremely curved space. Then we will known, with high precision, whether Einstein was right in his description of space, time and gravity, or if new physics is needed.

Galaxy evolution, cosmology and dark energy

The distribution of galaxies in our neighbourhood has been mapped in detail, but we lack such measurements towards the edge of the known Universe. Applying the vast sensitivity of the SKA to the 21-cm Hydrogen line, we will detect billion galaxies, out to distances of tens billions of parsec (or redshifht exceeding z=1). The resulting map of the large-scale structure will reveal the processes by which galaxies formed and grew. Imaging redshifted hydrogen emission will provide an unprecendented three-dimensional picture of the cosmic web. We can follow the evolution of the first ripples of structure seen in the cosmic microwave background into individual galaxies and clusters allowing us to measure the effects of the mysterious “dark energy” that is pushing the Universe apart.

Probing the Dark Ages – the first black holes and stars

The final frontier in cosmology is to fill in the gap between 300.000 years after the Big Bang when the Universe became transparent, and a billion years later, where young galaxies are seen. While new infrared telescopes should see the very first stars, the state of the Universe before the birth of those stars is only detectable through the radio emission from extremely red-shifted hydrogen. We expect to observe the primordial distribution of gas and watch it collapse to form these first stars. The SKA will give us the opportunity to observe the dawn of the Universe and see how it gradually lit up as stars and galaxies formed and evolved into the place we live.

The Cradle of life – searching for life and planets

Searching life on other words is a fundamental issue for astronomy and biology and an important question for humanity. The SKA will have a resolution of 1/10 of the Earth-Sun separation at 300 ligth-years distance, and should detect emission from the centimetre sized “pebbles” thought to be the first step in assembling Earth-like planets. Observing the process of planet, building will test us how these other worlds are formed. Biomolecules tracing the existence of life may be detected. The SKA will be sensitive enough to search for the first time for “interstellar TV” – the detection of such extraterrestrial signals would forever change the perception of humanity in the Universe.

The origin and evolution of cosmic magnetism

Electromagnetism is one of the best understood physical forces. It is therefore surprising that we still cannot answer basic questions about the origin and evolution of cosmic magnetic fields. Yet it is clear that magnetic fields are an important component of interstellar and intergalactic space. A polarised radio wave propagating through a magnetised region undergoes a systematic distortion known as “Faraday rotation”. By mapping the faint indications of this effect toward very distant galaxies, the SKA will be able to make detailed studies of magnetism in any intervening object. This new approach will reveal what cosmic magnets look like, how they formed, and what role they have played in the evolving Universe.

The SKA will be a highly flexible instrument designed to address a wide range of fundamental questions in astrophysics, fundamental physics, cosmology, particle astrophysics and astrobiology. It will be able to probe previously unexplored parts of the distant Universe.




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