16,578 research outputs found
The Square Kilometre Array
The Square Kilometre Array (SKA) is intended as the next-generation radio
telescope and will address fundamental questions in astrophysics, physics, and
astrobiology. The international science community has developed a set of Key
Science Programs:
(1) Emerging from the Dark Ages and the Epoch of Reionization,
(2) Galaxy Evolution, Cosmology, and Dark Energy,
(3) The Origin and Evolution of Cosmic Magnetism,
(4) Strong Field Tests of Gravity Using Pulsars and Black Holes, and
(5) The Cradle of Life/Astrobiology.
In addition, there is a design philosophy of "exploration of the unknown," in
which the objective is to keep the design as flexible as possible to allow for
future discoveries. Both a significant challenge and opportunity for the SKA is
to obtain a significantly wider field of view than has been obtained with radio
telescopes traditionally. Given the breadth of coverage of cosmic magnetism and
galaxy evolution in this conference, I highlight some of the opportunities that
an expanded field of view will present for other Key Science Programs.Comment: 8 pages; invited presentation at the Panoramic Radio Astronomy
conference, Groningen, The Netherlands; 2009 June 2--
Cosmology with the Square Kilometre Array
We argue that the Square Kilometre Array has the potential to make both
redshift (HI) surveys and radio continuum surveys that will revolutionize
cosmological studies, provided that it has sufficient instantaneous
field-of-view that these surveys can cover a hemisphere in a timescale ~1 yr.
Adopting this assumption, we focus on two key experiments which will yield
fundamental new measurements in cosmology, characterizing the properties of the
mysterious dark energy which dominates the dynamics of today's Universe.
Experiment I will map out ~10^9 HI galaxies to redshift z~1.5, providing the
premier measurement of the clustering power spectrum of galaxies: accurately
delineating the acoustic oscillations and the `turnover'. Experiment II will
quantify the cosmic shear distortion of ~10^10 radio continuum sources,
determining a precise power spectrum of the dark matter, and its growth as a
function of cosmic epoch. We contrast the performance of the SKA in precision
cosmology with that of other facilities which will, probably or possibly, be
available on a similar timescale. We conclude that data from the SKA will yield
transformational science as the direct result of four key features: (i) the
immense cosmic volumes probed, exceeding future optical redshift surveys by
more than an order of magnitude; (ii) well-controlled systematic effects such
as the narrow `k-space window function' for Experiment I and the
accurately-known `point-spread function' for Experiment II; (iii) the ability
to measure with high precision large-scale modes in the clustering power
spectra, for which nuisance effects such as non-linear structure growth,
peculiar velocities and `galaxy bias' are minimised; and (iv) different
degeneracies between key parameters to those which are inherent in the CMB.Comment: 20 pages, 8 figures. To appear in "Science with the Square Kilometer
Array", eds. C.Carilli and S.Rawlings, New Astronomy Reviews (Elsevier:
Amsterdam
An Overview of the Square Kilometre Array
The Square Kilometre Array (SKA) will be the premier instrument to study
radiation at centimetre and metre wavelengths from the cosmos, and in
particular hydrogen, the most abundant element in the universe. The SKA will
probe the dawn of galaxy formation as well as allow advances in many other
areas of astronomy, such as fundamental physics, astrobiology and cosmology.
Phase 1, which will be about 10% of the full SKA collecting area, will be built
in Australia and South Africa. This paper describes the key science drivers of
the SKA, provides an update on recent SKA Organisation activities and
summarises the baseline design for Phase 1.Comment: Proceedings of the SKA Science Workshop in East-Asia, Nagoya, Japan,
5 - 7 June 201
Magnetism in the Square Kilometre Array Era
The unprecedented sensitivity, angular resolution and broad bandwidth
coverage of Square Kilometre Array (SKA) radio polarimetric observations will
allow us to address many long-standing mysteries in cosmic magnetism science. I
will highlight the unique capabilities of the SKA to map the warm hot
intergalactic medium, reveal detailed 3-dimensional structures of magnetic
fields in local galaxies and trace the redshift evolution of galactic magnetic
fields.Comment: 4 pages, Invited paper, Proceedings of FM8 "New Insights in
Extragalactic Magnetic Fields", XXXth General Assembly of the IAU, Vienna,
August 20-31, 201
HI Science with the Square Kilometre Array
The Square Kilometre Array (SKA) will be a formidable instrument for the
detailed study of neutral hydrogen (HI) in external galaxies and in our own
Galaxy and Local Group. The sensitivity of the SKA, its wide receiver bands,
and the relative freedom from radio frequency interference at the SKA sites
will allow the imaging of substantial number of high-redshift galaxies in HI
for the first time. It will also allow imaging of galaxies throughout the Local
Volume at resolutions of <100 pc and detailed investigations of galaxy disks
and the transition between disks, halos and the intergalactic medium (IGM) in
the Milky Way and external galaxies. Together with deep optical and
millimetre/sub-mm imaging, this will have a profound effect on our
understanding of the formation, growth and subsequent evolution of galaxies in
different environments. This paper provides an introductory text to a series of
nine science papers describing the impact of the SKA in the field of HI and
galaxy evolution. We propose a nested set of surveys with phase 1 of the SKA
which will help tackle much of the exciting science described. Longer commensal
surveys are discussed, including an ultra-deep survey which should permit the
detection of galaxies at z=2, when the Universe was a quarter of its current
age. The full SKA will allow more detailed imaging of even more distant
galaxies, and allow cosmological and evolutionary parameters to be measured
with exquisite precision.Comment: 9 pages, 1 figure, accepted by Proceedings of Science as the HI
Overview Chapter for "Advancing Astrophysics with the Square Kilometre Array
Science Pipelines for the Square Kilometre Array
The Square Kilometre Array (SKA) will be both the largest radio telescope
ever constructed and the largest Big Data project in the known Universe. The
first phase of the project will generate on the order of 5 zettabytes of data
per year. A critical task for the SKA will be its ability to process data for
science, which will need to be conducted by science pipelines. Together with
polarization data from the LOFAR Multifrequency Snapshot Sky Survey (MSSS), we
have been developing a realistic SKA-like science pipeline that can handle the
large data volumes generated by LOFAR at 150 MHz. The pipeline uses task-based
parallelism to image, detect sources, and perform Faraday Tomography across the
entire LOFAR sky. The project thereby provides a unique opportunity to
contribute to the technological development of the SKA telescope, while
simultaneously enabling cutting-edge scientific results. In this paper, we
provide an update on current efforts to develop a science pipeline that can
enable tight constraints on the magnetised large-scale structure of the
Universe.Comment: Published in Galaxies, as part of a Special Issue on The Power of
Faraday Tomograph
Solar Physics with the Square Kilometre Array
The Square Kilometre Array (SKA) will be the largest radio telescope ever
built, aiming to provide collecting area larger than 1 km. The SKA will
have two independent instruments, SKA-LOW comprising of dipoles organized as
aperture arrays in Australia and SKA-MID comprising of dishes in South Africa.
Currently the phase-1 of SKA, referred to as SKA1, is in its late design stage
and construction is expected to start in 2020. Both SKA1-LOW (frequency range
of 50-350 MHz) and SKA1-MID Bands 1, 2, and 5 (frequency ranges of 350-1050,
950-1760, and 4600-15300 MHz, respectively) are important for solar
observations. In this paper we present SKA's unique capabilities in terms of
spatial, spectral, and temporal resolution, as well as sensitivity and show
that they have the potential to provide major new insights in solar physics
topics of capital importance including (i) the structure and evolution of the
solar corona, (ii) coronal heating, (iii) solar flare dynamics including
particle acceleration and transport, (iv) the dynamics and structure of coronal
mass ejections, and (v) the solar aspects of space weather. Observations of the
Sun jointly with the new generation of ground-based and space-borne instruments
promise unprecedented discoveries.Comment: Accepted for publication in Advances in Space Researc
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