The Square Kilometer Array. Presented by Simon Worster

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1 The Square Kilometer Array Presented by Simon Worster

2 The Square Kilometer Array SKA for short. Will contain over a square kilometer of collecting area. Will be the largest radio telescope ever built. Cores of the arrays based in Australia and Africa. Composed of three different types of radio receivers. 10 member countries contributing to project, including Canada (National Research Council).

3 High Frequency Receivers: 15 Meter Dishes Image Credit: SPDO, Swinburne Astronomy Productions[3]

4 High Frequency Array Frequencies up to 20 Ghz.[2] Several thousand once telescope is completed. Steerable, unlike low and mid frequency arrays. Built to tolerate harsh environment. Prototypes currently being built. Spread over thousands of kilometers from a core in Africa.

5 Mid Frequency Receivers: Mid-Frequency Aperture Array Image Credit: SPDO, Swinburne Astronomy Productions[3]

6 Mid Frequency Array For observing frequencies of 400 Mhz to 1.4 Ghz. Large field of view, on the order of a 100 square degrees.[2] Using computational methods the array can observe different areas of the sky. Extend out as far as 200km from the cores in Africa and Australia. Can observe multiple areas of the sky at once.

7 Low Frequency Receivers: Low-Frequency Aperture Array Image Credit: SPDO, Swinburne Astronomy Productions[3]

8 Low Frequency Array Covers frequencies from 50Mhz to 350Mhz.[2] Composed of stationary antennas, array is directed electronically. Array will contain a quarter of a million individual antennas. Spread out as far as 50km from the cores in Africa and Australia. Can observe multiple areas of the sky at once.

9 Interferometry The separation of receivers by up to thousands of kilometers causes a difference in phase between the signals received. By precisely recording the arrival time of the signal for each receiver, the signals can be combined to achieve high resolution images. Array will have a resolution of 40-2 mas when completed.[4] VLA has a resolution of mas.

10 Choice of Location Location of array cores chosen for their low human populations. High frequency receivers spread across Africa, array core based in South African desert. Dishes spread across continent to provide as many baselines between antenna as possible. Image Credit: Ant Schinckel, CSIRO.

11 History of Project 1991: First conception of idea. 2006: Suitable sites determined. 2008: Telescope system design begins. 2011: SKA Organisation created. 2012: Sites in Australia and Africa chosen. 2013: Costs determined. 2013: Component design began. 2014: Acquiring Phase 1 funding.

12 Future of Project 2016: Phase 1 funding acquired. 2016: Deployment of prototypes. 2018: Phase 1 construction begins. 2020: First Observations. 2023: Phase 1 construction ends. 2023: Phase 2 construction begins. 2030: Phase 2 construction ends.

13 Motivation for Construction 50 times more sensitive than today's best radio telescopes. Survey speeds up to times faster than today's best radio telescopes. Construction of telescope will require technologies not yet developed. Will require advancements in antenna and dish design. Computers must be developed that can process the vast amounts of information.

14 Strong Field Tests of Gravity To further test the limits of general relativity, observations of objects outside the solar system are needed. Objects with high velocities and high gravitational potentials such as black holes and pulsars need to be observed. SKA would have the sensitivity needed to further the limits of general relativity or require the creation of new theories of gravity.[1]

15 Dark Energy and Dark Energy By observing the 1420Mhz (21cm) emission of neutral hydrogen the distribution of matter in galaxies and the universe can be observed. Using the Doppler shift in hydrogen emission, the expansion of the Universe due to Dark Energy can be studied. Anomalies in the rotation rates in galaxies due to Dark Matter can be studied using the Doppler shift as well.

16 Radio image of spiral galaxy M51, taken with VLA, blue colour is emission from neutral H. Image Credit: Image courtesy of NRAO/AUI

17 The Early Universe SKA will be able to see further, and therefore further back in time. Observe the period years after the Big Bang. Period when the Universe contained mostly neutral hydrogen, before the first objects began to form. First objects began to ionize the hydrogen in the Universe, allowing SKA to observe the period of formation of the first galaxies.[5]

18 Image Credit: S. Baek, P. Di Matteo, B. Semelin, F. Combes, and Y. Revaz[7]

19 Search for Life Will be able to observe the formation of protoplanetary disks, which can lead to the formation of Earth like planets. Can look for known transitions of molecules which are known building blocks for life on the Earth. Could possibly observe the effects of the magnetic fields of larger planets. Could detect typical radar signals from 1000 closest planets (within ~15pc).[6]

20 Conclusions Large contribution to science, based on power alone. Prototypes of different arrays not yet complete, technologies need to be developed. Funding not yet complete, don't get your hopes up. Even if partially completed, would still be several times better than any current radio telescopes.

21 References: [1]M. Kramer, 'Strong-Field Tests of Gravity Using Pulsars and Black Holes', arxiv:astro-ph/ , [2] The Square Kilometre Array SKA Home, [Online]. Available: [Accessed: 15- Jan- 2016]. [3] Swinburne Astronomy Productions, [Online]. Available: [Accessed: 15- Jan- 2016]. [4]L. E. H. Godfrey, H. Bignall, S. Tingay, L. Harvey-Smith, M. Kramer, S. Burke-Spolaor, et al., 'Very High Angular Resolution Science with the Square Kilometre Array', PASA, vol. 29, no. 1, pp , [5]Roy Maartens, Filipe B. Abdalla, Matt Jarvis, Mario G. Santos, 'Cosmology with the SKA -- overview', arxiv: , [6]Hoare, M.; Perez, L.; Bourke, T. L.; Testi, L.; Jimenez-Serra, I.; Zarka, P., et al., 'SKA and the Cradle of Life', AASKA14, 9-13 June, [7]S. Baek1, P. Di Matteo, B. Semelin, F. Combes, and Y. Revaz, 'The simulated 21 cm signal during the epoch of reionization: full modeling of the Ly-α pumping', A&A, vol. 495, pp , 2009.

SKA Precursors and Pathfinders. Steve Torchinsky

SKA Precursors and Pathfinders Steve Torchinsky steve.torchinsky@obspm.fr A square kilometre of collecting area for each of three frequency bands SKA Low frequency 50MHz to 450MHz to be built in Western