Transcript The Square Kilometre Array

The Square Kilometre Array
Department of Astronomy and Atmospheric Sciences, Kyungpook National University
김경묵, 박진태, 방태양, 신지혜, 조창현, 정수진, 현화수
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Outline
< Section 2 >
< Section 1 >
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Introduction
The Science
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What is the SKA?
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Extreme tests of general relativity
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The SKA Timeline
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How do Galaxies Evolve?
Phase Development
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What is Dark Energy?
The SKA Telescopes
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Around the re-ionization epoch!
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Understanding Cosmic Magnetism
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Cradle of Life : Searching for life and
planets
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Aperture Array
The Properties of the SKA
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Sky coverage & Resolution
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Sensitivity & Depth
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Data access
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Introduction : What is the SKA?
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The Square Kilometre Array
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The largest, most sensitive radio telescope with an aim to provide fundamental
answers to questions about the origin and evolution of the universe.
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Telescopes will be co-located in Africa and in Australia.
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South Africa(Karoo desert) : the high and mid frequencies.
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Australia(Murchison region) : the low frequency and survey instrument.
South Africa
Australia
(Image from the SKA official webpage)
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(Image from the SKA official webpage)
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The SKA Telescopes
Low Frequency
Mid Frequency
High Frequency
(Image from the SKA official webpage)
Telescope
Freq.
Freq. Range
Collector
Number & Size
Distribution
Low
70 MHz ~ 450 MHz
Aperture array
250 arrays, D = 180 m
66% within 5 km diameter core
33% on 5 spiral arms to 180 km
Mid
400 MHz ~ 1.4 GHz
Aperture array
250 arrays, D = 56 m
66% within 5 km diameter core
33% on 5 spiral arms to 180 km
2,500 dishes, D = 15 m
50% 5 km diameter core
25% - core to 180 km,
25% - 180km ~ 3,000km
High
1.2 GHz ~ 10 GHz
Dishes
Information from “https://connect.innovateuk.org/web/ska/overview”
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Aperture Array (AA)
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AA is key feature of the SKA.
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AA is a large number of small, fixed antenna elements
coupled to appropriate receiver systems.
Advantages of AA
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Unblocked aperture with full view of the entire sky!
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Ultimate flexibility and reliability - no moving parts!
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Beams are formed and controlled electronically!
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Multiple beams (or FOV) permits concurrent, independent (or associated) observations
→ huge FOV!
(http://ska-ptafrica.org)
Low Frequency AA
Mid Frequency AA
(Image from the SKA official webpage)
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The SKA Timeline
(Image from the SKA official webpage)
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Phased Development
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SKA Phase 1 (2018~)
South Africa
Australia
HIGH
(http://ska-ptafrica.org)
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Phased Development
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SKA Phase 2 (mid 2020s)
South Africa
Australia
HIGH
(http://ska-ptafrica.org)
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The Telescope Scale comparison
(Image from the SKA official webpage)
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The Properties of Instruments
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Sky coverage & Resolution
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Sky coverage
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The SKA Phase 1 shall be able to provide access to at least 2π sr of the sky.
Resolution
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Angular resolution is about to < 0.1 arcsecond at 1.4 GHz
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~3000 km base line
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Sensitivity & Depth
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The typical survey’s depth is z∼0.2 with massive galaxies detected out to z∼0.7.
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SKA will have sufficient sensitivity to detect all QSOs and starforming galaxies to
z~20.
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~ 50 times more sensitive than the currently most powerful interferometer.
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The structure of the universe would be sampled over scales of 10’s of Mpc to several Gpc.
Depth
Sensitivity
(https://connect.innovateuk.org/web/ska/ov
erview)
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(Taylor, A.R. et al. 1999)
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Data access
Optical fibres will be essential to
transport the huge amount of data to the
central SKA processor.
(Image from The Aperture Arrays for the SKA: the SKADS White Paper 4.2010.)
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Data access
Optical fibres will be essential to
transport the huge amount of data to the
central SKA processor.
(Image from The Aperture Arrays for the SKA: the SKADS White Paper 4.2010.)
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The Science
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The Key Projects
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Extreme tests of general relativity
How do Galaxies Evolve?
What is Dark Energy?
Around the re-ionization epoch!
Understanding Cosmic Magnetism
Cradle of Life : Searching for life and planets
(Image from the SKA official webpage)
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Extreme tests of general relativity
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Was Einstein right or will general relativity eventually fail?
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What are the properties of black holes?
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Are there still ripples in space-time from the early Universe?
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The SKA will test general relativity extremely with pulsars and black holes.
The best test so far
of Einstein’s theory
in strong
gravitational fields is
provided by the only
known double pulsar
system, where two
pulsars orbit each
other in 145 min.
Pulsars orbiting black holes will test
Einstein’s description of these enigmatic
objects to the extreme.
(Image from the SKA Brochure)
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Pulsars discovered and
monitored with the SKA
will act like a cosmic
gravitational wave
detector, allowing the
study of ripples in the
fabric of space-time
that propagate at ultralow frequencies.
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How do Galaxies Evolve?
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Radio telescopes’ ability to “see” regions beyond the optical view of a
galaxy, have brought significant insights into how galaxies form and
develop.
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The SKA’s sensitivity and resolution will be able to track young,
newly forming galaxies at cosmological distances, and, through
mapping the distribution of H.
(Image from the SKA official webpage)
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What is Dark Energy?
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Mysterious force appears to counteract and even
surpass the mutual gravitational attraction causing
acceleration in the expansion.
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cosmology and dark energy is to observe the gravitational effects of galaxies and
clusters of galaxies on the path of radio waves through the Universe.
(Image from the SKA official webpage)
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Around the re-ionization epoch!
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Take snapshots of the 21 cm emission at many different epochs, before, during and
after reionisation, yielding detailed information about the formation of the first
structures in the universe.
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But! these objects are exceptionally faint and much of their light is absorbed by
intervening matter as it travels toward us.
SKA can resolve this problem thanks to it’s very high sensitivity!
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Through multifrequency observations, we can therefore construct fully threedimensional maps of neutral gas in the universe.
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Such maps are crucial for studying the time dependence of reionisation.
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Around the re-ionization epoch!
(Furlanetto et al. 2003)
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Understanding Cosmic Magnetism
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What is the shape and strength of the magnetic field in
our Milky Way?
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How does this compare to the magnetism in other
galaxies?
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What role has this had on the formation of individual
stars and galaxies?
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Where and how do the magnetic fields originate?
(Image from the SKA official webpage)
(Image from the SKA official webpage)
(Image from Philipp P. Kronberg, Physics Today, 12. 2002, p.30)
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Cradle of Life : Searching for life and planets
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The SKA will detect the thermal emission from dust in the habitable zone. In particular,
the SKA will show where dust evolves from micron-sized insterstellar particles to
centimetre-sized and larger “pebbles”.
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Astrobiologists will use the SKA to search for amino acids, the building blocks of life,
by identifying their spectral signatures at specific frequencies.
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The SKA will be able to detect extremely weak extraterrestrial radio signals if they
were to exist.
(Image from the SKA official webpage)
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Reference
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Papers
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Furlanetto, S. R., & Loeb, A. 2003, AJ, 588, 18
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Nadin, Maureen et al. 2011, JRASC, 105, 15
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Kronberg, P. P., Physics Today, 12. 2002, p.30
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Taylor, A.R. 1999, in M.P. van Haarlam (ed.), Perspectives on Radio Astronomy : Science with
Large Antenna Arrays, ASTRON, p. 1
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The Aperture Arrays for the SKA: the SKADS White Paper (2010.4)
Webpages
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The SKA official Webpage (https://www.skatelescope.org)
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The SKA Technology subgroup (https://connect.innovateuk.org/web/ska/)
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Workshop webpage
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The Square Kilometre Array: a large Scale ESFRI Infrastructure, From the Cosmos to the Cities of the future
(http://ska-ptafrica.org/index.html)
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