From SKA: “New paper highlights breadth of cosmology to be done with SKA”


From SKA

8 November 2018

A new paper published yesterday highlights the potential of the SKA to tackle key questions of cosmology, by presenting a detailed overview of the various observation campaigns that can be conducted with the telescope once built.

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The SKA will probe key issues in cosmology and investigate why the Universe is expanding at an accelerating rate. (Credit: NASA/WMAP)

Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

Cosmology is the study of the origin and fate of the Universe. Cosmologists believe that ordinary matter – the matter that forms everything we see including planets and galaxies – only accounts for around 5% of the total mass & energy content of the Universe. Two mysterious components seem to constitute the rest with dark matter – matter we can’t see directly but whose gravitational effects on normal matter we can observe – constituting around 27% of the remaining content and dark energy – the force causing the Universe to expand at an accelerated rate – accounting for the remaining 68%.

The Red Book as it is called is the product of the SKA’s Cosmology Science Working Group, a group of around 130 scientists from 70 different institutes in 19 countries interested in using the SKA that represents the wider cosmology community*. It builds on the work of the 2015 SKA Science Book, taking into account the major developments in the field since then. With 46 authors from 36 institutes contributing directly to the writing of the paper, it represents a significant piece of work on the science potential of the SKA to address key issues in cosmology such as dark matter and dark energy.

“We know the Universe is expanding at an accelerating rate, but we don’t yet understand why,” explains Prof. Richard Battye, co-chair of the working group from the University of Manchester. “One of the SKA’s main science goals is to investigate this, by looking at the distribution of the most basic element, hydrogen, throughout the cosmos. We hope to go beyond what is now considered the ‘standard’ cosmological model and further refine our estimates of the amounts of dark matter and dark energy at any given time in the Universe.”

The Red Book details the cosmological surveys that the SKA will carry out, and the science they will enable, including establishing the proportion of dark energy in the Universe thanks to percent-level precision measurements of its expansion rate over the last 12 billion years.

“Science is a constantly evolving field, so we have to update our research to reflect new discoveries and the advance of techniques,” adds SKA Project Scientist Dr. Anna Bonaldi, a co-author of the paper. “As we near the start of construction, the design of the SKA has also matured, so this needs to be reflected in our predictions.”

There have been major discoveries in the past few years which have implications for the field of cosmology, including the detection of gravitational waves predicted by Einstein by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States, and the detection by the EDGES experiment located on the site of the future SKA-low telescope in Western Australia of what could be the signal from some of the first stars to form in the universe, one of the key science goals of the SKA.

EDGES telescope in a radio quiet zone at the Murchison Radio-astronomy Observatory in Western Australia.

These discoveries bring new questions within cosmology, especially on the nature of dark matter. Astronomers are now working on their observational implications and how the SKA could help to confirm the results, in particular through synergies with other upcoming ground-breaking telescopes which observe the Universe at different wavelengths such as ESA’s Euclid space telescope and the Large Synoptic Survey Telescope (LSST) being built in Chile.

ESA/Euclid spacecraft

LSST


LSST Camera, built at SLAC



LSST telescope, currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

“The SKA will be the first radio telescope to be a major actor in the field of cosmology,” says Dr. Laura Wolz, co-chair of the working group and a Research Fellow at the University of Melbourne. “With it we’ll be able to produce the first ever map of the large-scale structure of the Universe back to a time when it was 2.2 billion years old – this is incredibly exciting for cosmologists, as it will enable new science and unpredicted discoveries.”

*A total of 13 Science Working Groups and Focus Groups representing more than 500 scientists across 20 countries work on developing the science case of the SKA. From Cosmology to Magnetism & Solar Physics, they cover the various fields of interested users from the astronomical community.

See the full article here .

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SKA ASKAP Pathefinder Telescope

SKA Meerkat telescope, 90 km outside the small Northern Cape town of Carnarvon, SA


SKA Meerkat Telescope

Murchison Widefield Array,SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO)


SKA Murchison Wide Field Array
About SKA

The Square Kilometre Array will be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, led by SKA Organisation. The SKA will conduct transformational science to improve our understanding of the Universe and the laws of fundamental physics, monitoring the sky in unprecedented detail and mapping it hundreds of times faster than any current facility.

Already supported by 10 member countries – Australia, Canada, China, India, Italy, New Zealand, South Africa, Sweden, The Netherlands and the United Kingdom – SKA Organisation has brought together some of the world’s finest scientists, engineers and policy makers and more than 100 companies and research institutions across 20 countries in the design and development of the telescope. Construction of the SKA is set to start in 2018, with early science observations in 2020.