## From Symmetry: “Tuning in for science”

Symmetry

08/01/17
By Mike Perricone

Square Kilometer Array

The sprawling Square Kilometer Array radio telescope hunts signals from one of the quietest places on earth.

SKA South Africa

When you think of radios, you probably think of noise. But the primary requirement for building the world’s largest radio telescope is keeping things almost perfectly quiet.

Radio signals are constantly streaming to Earth from a variety of sources in outer space. Radio telescopes are powerful instruments that can peer into the cosmos—through clouds and dust—to identify those signals, picking them up like a signal from a radio station. To do it, they need to be relatively free from interference emitted by cell phones, TVs, radios and their kin.

NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

That’s one reason the Square Kilometer Array is under construction in the Great Karoo, 400,000 square kilometers of arid, sparsely populated South African plain, along with a component in the Outback of Western Australia. The Great Karoo is also a prime location because of its high altitude—radio waves can be absorbed by atmospheric moisture at lower altitudes. SKA currently covers some 1320 square kilometers of the landscape.

Even in the Great Karoo, scientists need careful filtering of environmental noise. Effects from different levels of radio frequency interference (RFI) can range from “blinding” to actually damaging the instruments. Through South Africa’s Astronomy Geographic Advantage Act, SKA is working toward “radio protection,” which would dedicate segments of the bandwidth for radio astronomy while accommodating other private and commercial RF service requirements in the region.

“Interference affects observational data and makes it hard and expensive to remove or filter out the introduced noise,” says Bernard Duah Asabere, Chief Scientist of the Ghana team of the African Very Long Baseline Interferometry Network (African VLBI Network, or AVN), one of the SKA collaboration groups in eight other African nations participating in the project.

The Ghanaian and South African governments on Thursday announced the combination of ‘first light’ science observations, which confirm the successful conversion of the Ghana communications antenna from a redundant telecoms instrument into a functioning Very Long Baseline Interferometry (VLBI) radio telescope.

Ghana is the first partner country of the African Very Large Baseline Interferometer (VLBI) Network (AVN) to complete the conversion of a communications antenna into a functioning radio telescope.

SKA “will tackle some of the fundamental questions of our time, ranging from the birth of the universe to the origins of life,” says SKA Director-General Philip Diamond. Among the targets: dark energy, Einstein’s theory of gravity and gravitational waves, and the prevalence of the molecular building blocks of life across the cosmos.

SKA-South Africa can detect radio spectrum frequencies from 350 megahertz to 14 gigahertz. Its partner Australian component will observe the lower-frequency scale, from 50 to 350 megahertz. Visible light, for comparison, has frequencies ranging from 400 to 800 million megahertz. SKA scientists will process radiofrequency waves to form a picture of their source.

A precursor instrument to SKA called MeerKat (named for the squirrel-sized critters indigenous to the area), is under construction in the Karoo.

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

This array of 16 dishes in South Africa achieved first light on June 19, 2016. MeerKAT focused on 0.01 percent of the sky for 7.5 hours and saw 1300 galaxies—nearly double the number previously known in that segment of the cosmos.

Since then, MeerKAT met another milestone with 32 integrated antennas. MeerKat will also reach its full array of 64 dishes early next year, making it one of the world’s premier radio telescopes. MeerKAT will eventually be integrated into SKA Phase 1, where an additional 133 dishes will be built. That will bring the total number of antennas for SKA Phase I in South Africa to 197 by 2023. So far, 32 dishes are fully integrated and are being commissioned for science operations.

On completion of SKA 2 by 2030, the detection area of the receiver dishes will exceed 1 square kilometer, or about 11,000 square feet. Its huge size will make it 50 times more sensitive than any other radio telescope. It is expected to operate for 50 years.

SKA is managed by a 10-nation consortium, including the UK, China, India and Australia as well as South Africa, and receives support from another 10 countries, including the US. The project is headquartered at Jodrell Bank Observatory in the UK.

The full SKA will use radio dishes across Africa and Australia, and collaboration members say it will have a farther reach and more detailed images than any existing radio telescope.

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

In preparation for the SKA, South Africa and its partner countries developed AVN to establish a network of radiotelescopes across the African continent. One of its projects is the refurbishing of redundant 30-meter-class antennas, or building new ones across the partner countries, to operate as networked radio telescopes.

Hartebeesthoek Radio Astronomy Observatory in Gauteng.

The first project of its kind is the AVN Ghana project, where an idle 32-meter diameter dish has been refurbished and revamped with a dual receiver system at 5 and 6.7 gigahertz central frequencies for use as a radio telescope. The dish was previously owned and operated by the government and the company Vodafone Ghana as a telecommunications facility. Now it will explore celestial objects such as extragalactic nebulae, pulsars and other RF sources in space, such as molecular clouds, called masers.

Asabere’s group will be able to tap into areas of SKA’s enormous database (several supercomputers’ worth) over the Internet. So will groups in Botswana, Kenya, Madagascar, Mauritius, Mozambique, Namibia and Zambia. SKA is also offering extensive outreach in participating countries and has already awarded 931 scholarships, fellowships and grants.

Other efforts in Ghana include introducing astronomy in the school curricula, training students in astronomy and related technologies, doing outreach in schools and universities, receiving visiting students at the telescope site and hosting programs such as the West African International Summer School for Young Astronomers taking place this week.

Asabere, who achieved his advanced degrees in Sweden (Chalmers University of Technology) and South Africa (University of Johannesburg), would like to see more students trained in Ghana, and would like get more researchers on board. He also hopes for the construction of the needed infrastructure, more local and foreign partnerships and strong governmental backing.

“I would like the opportunity to practice my profession on my own soil,” he says.

That day might not be far beyond the horizon. The Leverhulme-Royal Society Trust and Newton Fund in the UK are co-funding extensive human capital development programs in the SKA-AVN partner countries. A seven-member Ghanaian team, for example, has undergone training in South Africa and has been instructed in all aspects of the project, including the operation of the telescope.

Several PhD students and one MSc student from Ghana have received SKA-SA grants to pursue further education in astronomy and engineering. The Royal Society has awarded funding in collaboration with Leeds University to train two PhDs and 60 young aspiring scientists in the field of astrophysics.

Based on the success of the Leverhulme-Royal Society program, a joint UK-South Africa Newton Fund intervention (DARA—the Development in Africa with Radio Astronomy) has since been initiated in other partner countries to grow high technology skills that could lead to broader economic development in Africa.

As SKA seeks answers to complex questions over the next five decades, there should be plenty of opportunities for science throughout the Southern Hemisphere. Though it lives in one of the quietest places, SKA hopes to be heard loud and clear.

Stem Education Coalition

Symmetry is a joint Fermilab/SLAC publication.

## From astrobites: “Bubbles from reionization at the cosmic dawn”

Astrobites

Title: Dark-ages reionization & galaxy formation simulation XII: Bubbles at dawn
Authors: Paul Geil, Simon Mutch, Gregory Poole, Alan Duffy, Andrei Mesinger, and Stuart Wyithe
First Author’s Institution: University of Melbourne, Parkville, Victoria, Australia

Status: Submitted to MNRAS, open access

The early universe encompasses many scarcely understood phenomena both cosmological and astrophysical that we hope to begin exploring. This can be made possible by looking at the highly redshifted 21cm emission (see here for why this emission happens) from neutral hydrogen which puts these observations from the cosmic dawn relevant to today’s astrobite into the radio frequency range of 100-140 MHz. But this signal is notoriously faint, and requires some of the most sensitive instruments ever designed to observe it. Currently this is an emerging field where most of the instruments with the necessary sensitivity are only now entering the development stage. This certainly won’t stop us from understanding the potential pitfalls we may encounter along the way in measuring the early universe. We can of course anticipate how well we can detect this signal through simulations of the 21cm emission and our next generation radio telescopes.

Cosmic Dawn and Galactic Reionization Bubbles

When the first galaxies began to form they also began to emit UV radiation. This UV radiation reionized the surrounding neutral hydrogen, which means that it can no longer emit the 21cm emission. From our perspective when observing this we see large spherical holes (bubbles) begin to form over time, making a ‘Swiss cheese’-like effect at the largest scales. To make up for a lack of bubble observations, simulations of bubble formation from the Dark ages Reionization & Galaxy Formation Simulation (DRAGONS) (for an example see Fig. 1) were created.

Fig 1: Example of two galaxies with similar luminosities and solar mass from the DRAGON simulation. The progression of reionization of the galaxies is seen in the form of growing bubble size over redshift.

Using information about mean bubble size and luminosity from DRAGONS, a relationship between the two can be found. This helps us in sampling appropriate galaxies to survey from the future Wide-Field Infrared Survey Telescope High Latitude Survey (WFIRST-HLS).

NASA/WFIRST

Fig 2. shows that the mean bubble size \bar{R}, increases linearly with luminosity. (Another example of associating bubble size and luminosity can be seen in this astrobite.)

Fig. 2: The authors show through simulation of reionization bubbles around galaxies that they have a linear relationship between the mean bubble size \bar{R} and the UV magnitude M_{UV}

1cm Bubble Observing with the SKA

The Square Kilometer Array (SKA) is an upcoming radio interferometer array located in South Africa and Western Australia.

SKA-Square Kilometer Array

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

It will consist of 1 sq. km of collecting area, making it the most sensitive array to ever exist, and a perfect instrument for observing the 21cm signal. Observation of the 21cm signal is dependent on the differential brightness temperature, \delta T_b.

\delta T_b \propto x_{HI}(1+\delta)(1 – \frac{T_{\gamma}}{T_{S}})

The differential brightness temperature depends on the dark matter over-density \delta (small fluctuations in the density), the spin temperature T_S, the CMB temperature T_{\gamma}, and the fraction of neutral hydrogen x_{HI}. It’s important to note that \delta T_b is spatially dependent, as both \delta and x_{HI} depend on position.

For simulating the observation of the 21cm differential brightness temperature from the cosmic dawn, they use the SKA1-Low specifications which determine the sensitivity (see here for some basic interferometry) and observational hours required . But the sensitivity of the SKA isn’t enough, so stacking spectra (averaging observations over frequency) must be used. By focusing on high redshift galaxies (z > 9) predicted from the WFIRST-HLS, and stacking future SKA1-Low observations centered on these galaxies, the bubbles from reionization should be observable. An example of how likely these bubbles can be measured is seen in Fig. 3, which shows that the signal to noise ratio (SNR) grows considerably for stacking 100+ galaxy observations in the case where T_{S} >> T_{\gamma} (right).

Fig. 3: The SNR for observing reionization bubbles increases if more spectra are stacked (100,200,300) and if \delta T_b is saturated (right), which means \delta T_b >> T_{\gamma}.

It appears from the author’s results that imaging individual bubbles from reionization doesn’t seem too likely as there is too much uncertainty in redshift and a high sensitivity required from the radio interferometer. But the technique the authors of today’s astrobite describe of stacking spectra over many galaxies does appear to provide that extra sensitivity for a measurement. There is also the big caveat of this being an ideal case, because our observations of the early universe are troubled by bright galactic and extragalactic foregrounds. The work in this astrobite also demonstrates that making a measurement of reionization and its characteristic bubbles may rely on a synthesized approach e.g. using both 21cm and near infrared observations.

Stem Education Coalition

What do we do?

Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.

Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

## From SKA: “International team completes large survey of gas in nearby galaxies”

SKA

An international team of investigators led by Dr. Claudia Cicone (INAF – Astronomical Observatory of Brera), Dr. Matt Bothwell (University of Cambridge) and with the SKA Organisation Project Scientist Dr. Jeff Wagg as principal investigator have found the spectra of the carbon monoxide emission line in a sample of small but nearby galaxies and found that the most massive galaxies form stars and are rich in metals.

The 12m APEX ESO telescope, located on the plateau of Chajnantor in Chile, at 5000m altitude.

The team, comprising investigators from Italy, the UK, Germany, Chile and China have completed a large survey of molecular gas in nearby galaxies using the 12m APEX telescope in Chile. The APEX Low-redshift Legacy Survey of MOlecular Gas (ALLSMOG, PI: Dr. Jeff Wagg) has observed the Carbon Monoxide (CO) molecule in a sample of 97 galaxies in the local Universe. The ALLSMOG data provide important information on the cold molecular gas content of these galaxies which have been well characterised in terms of their star-formation rates, gas-phase metallicities and atomic HI gas masses.

ALLSMOG is an ESO observing program conceived by Dr. Jeff Wagg to study the molecular gas through the carbon monoxide emission line with the telescope Atacama Pathfinder Experiment (Apex), a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (Oso) and ESO, which is located on the plain of Chajnantor at 5000 meters above sea level, in the Chilean Andes.

The article The final release date of ALLSMOG: a survey of CO in typical local low-M star-forming galaxies published today in the journal Astronomy & Astrophysics includes observations of 97 galaxies, 88 of whom studied with Apex (for more than 300 hours of observation from summer 2013 to winter 2015/2016) and 9 with the telescope of the Institute of millimetric radio astronomy (Iram) to Pico Veleta, Spain (between 2014 and 2015).

IRAM 30m Radio telescope, on Pico Veleta in the Spanish Sierra Nevada

The survey is the first major campaign ALLSMOG systematic observation of carbon monoxide extragalactic made with Apex telescope.

“The ALLSMOG survey is the first large systematic extragalactic survey of CO ever conducted with the APEX telescope”, says Claudia Cicone, a Marie Skłodowska-Curie fellow at INAF- Osservatorio Astronomico di Brera. “Our research has an enormous legacy value because the entire scientific community can exploit our data. We really hope our efforts will stimulate new ideas and results.”

“For all the galaxies in our sample we have additional information on their physical properties from optical observations and on their atomic gas content (HI) from radio observations of the HI21cm line published in previous studies and by other teams. We have created a real identikit of these galaxies which allows us to study the relations between the molecular gas and their other physical properties.”

“In the near future, multi-wavelength galaxy studies like this will be greatly enhanced by data from the SKA telescope and its precursors such as ASKAP and MeerKAT”, says Dr. Jeff Wagg.

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

“While the SKA precursors are expected to detect more than half a million galaxies in HI line emission, these sample sizes have the potential to increase by nearly an order of magnitude when the SKA1-mid telescope comes online.”

SKA1-mid is the dish array telescope to be built in South Africa that will be operating in the 350Mhz -14Ghz frequency range, complementary to the low-frequency telescope (so-called SKA1-low) to be built in Australia. Although SKA1-mid and the SKA precursors do not have the frequency coverage needed to measure the molecular gas in nearby galaxies, they will be able to detect the atomic gas through the 21cm atomic HI line transition.

“Quantifying the total gas content (atomic and molecular) of significant samples of galaxies out to large distances remains one of the crucial elements needed for a full understanding of galaxy formation”, concludes Dr. Jeff Wagg.

Stem Education Coalition

SKA Murchison Wide Field Array

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.

## From ICRAR: “Astronomers probe swirling particles in halo of starburst galaxy’

March 28, 2017

NGC253 starburst galaxy in optical (green; SINGG Survey) and radio (red; GLEAM) wavelengths. The H-alpha line emission, which indicates regions of active star formation, is highlighted in blue (SINGG Survey; Meurer+2006). Credits: A.D. Kapinska, G. Meurer. ICRAR/UWA/CAASTRO.

Astronomers have used a radio telescope in outback Western Australia to see the halo of a nearby starburst galaxy in unprecedented detail.

A starburst galaxy is a galaxy experiencing a period of intense star formation and this one, known as NGC 253 or the Sculptor Galaxy, is approximately 11.5 million light-years from Earth.

“The Sculptor Galaxy is currently forming stars at a rate of five solar masses each year, which is a many times faster than our own Milky Way,” said lead researcher Dr Anna Kapinska, from The University of Western Australia and the International Centre for Radio Astronomy Research (ICRAR) in Perth.

The Sculptor Galaxy has an enormous halo of gas, dust and stars, which had not been observed before at frequencies below 300 MHz. The halo originates from galactic “fountains” caused by star formation in the disk and a super-wind coming from the galaxy’s core.

The study used data from the ‘GaLactic and Extragalactic All-sky MWA’, or ‘GLEAM’ survey, which was observed by the Murchison Widefield Array (MWA) radio telescope located in remote Western Australia.

Murchison Widefield Array (MWA) radio telescope

“With the GLEAM survey we were able, for the first time, to see this galaxy in its full glory with unprecedented sensitivity at low radio frequencies,” said Dr Kapinska.

“We could see radio emission from electrons accelerated by supernova explosions spiralling in magnetic fields, and absorption by dense electron-ion plasma clouds —it’s absolutely fascinating.”

The MWA is a precursor to the Square Kilometre Array (SKA) radio telescope, part of which will be built in Western Australia in the next decade.

Co-author Professor Lister Staveley-Smith, from ICRAR and the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), said the SKA will be the largest radio telescope in the world and will be capable of discovering many new star-forming galaxies when it comes online.

“But before we’re ready to conduct a large-scale survey of star-forming and starburst galaxies with the SKA we need to know as much as possible about these galaxies and what triggers their extreme rate of star formation,” he said.

PUBLICATION DETAILS

Spectral Energy Distribution and Radio Halo of NGC 253 at Low Radio Frequencies, published in the Astrophysical Journal on March 28th, 2017.

Stem Education Coalition

ICRAR is an equal joint venture between Curtin University and The University of Western Australia with funding support from the State Government of Western Australia. The Centre’s headquarters are located at UWA, with research nodes at both UWA and the Curtin Institute for Radio Astronomy (CIRA).
ICRAR has strong support from the government of Australia and is working closely with industry and the astronomy community, including CSIRO and the Australian Telescope National Facility, iVEC, and the international SKA Project Office (SPO), based in the UK.

ICRAR is:

Playing a key role in the international Square Kilometre Array (SKA) project, the world’s biggest ground-based telescope array.

Attracting some of the world’s leading researchers in radio astronomy, who will also contribute to national and international scientific and technical programs for SKA and ASKAP.
Creating a collaborative environment for scientists and engineers to engage and work with industry to produce studies, prototypes and systems linked to the overall scientific success of the SKA, MWA and ASKAP.

A Small part of the Murchison Widefield Array

Enhancing Australia’s position in the international SKA program by contributing to the development process for the SKA in scientific, technological and operational areas.
Promoting scientific, technical, commercial and educational opportunities through public outreach, educational material, training students and collaborative developments with national and international educational organisations.
Establishing and maintaining a pool of emerging and top-level scientists and technologists in the disciplines related to radio astronomy through appointments and training.
Making world-class contributions to SKA science, with emphasis on the signature science themes associated with surveys for neutral hydrogen and variable (transient) radio sources.
Making world-class contributions to SKA capability with respect to developments in the areas of Data Intensive Science and support for the Murchison Radio-astronomy Observatory.

## From CSIRO: Women in STEM – “One woman’s role in designing the world’s largest radio telescope” Mia Baquiran

Commonwealth Scientific and Industrial Research Organisation

10th March 2017
Helen Sim

Mia Baquiran. When they flick the switch on the world’s largest telescope, one woman’s work will come to life.

If it takes a village to raise a child, it takes a planet – or at least ten countries – to build the the world’s largest radio telescope, the Square Kilometre Array.

The Square Kilometre Array, or SKA, is a next-generation radio telescope that will be vastly more sensitive than the best present-day instruments. It will give astronomers remarkable insights into the formation of the early Universe, including the emergence of the first stars, galaxies and other structures.

Consisting of thousands of antennas linked together by high bandwidth optical fibre, the SKA will require new technologies and progress in fundamental engineering. The telescope’s design and development is being led by the international SKA Organisation.

Radio telescopes add to observations made by optical and other telescopes by revealing different information about stars, galaxies and gas clouds. Because radio waves can pass through clouds of dust and gas, radio telescopes are able to observe objects and processes not visible to other telescopes.

An artist’s impression of the Square Kilometre Array’s antennas in Australia. ©SKA Organisation

Construction is due to start in 2018 and around the globe 11 groups, all with members from several countries, are working feverishly on different aspects of the project to make it come together.

Australia has a presence in several of these groups, and indeed leads two of them. Our very own Mia Baquiran is one of the researchers working on this exciting project.

She spends her days in a quiet, ground-floor office in a leafy suburb of Sydney, working on systems that will go into the international SKA radio telescope.

Mia’s role in this ‘moon-shot’ project concerns a telescope called ‘SKA Low’, an assembly of more than a quarter of a hundred thousand low-frequency antennas that will be housed at CSIRO’s Murchison Radio-astronomy Observatory in Western Australia.

CSIRO’s ASKAP antennas under construction at the Murchison Radio-astronomy Observatory in Western Australia

SKA Low has no moving parts but it is still a complex beast. The signals from the antennas have to be brought together and compared with each other (‘correlated’) to create a view of the sky.

Mia is working on the system (the correlator and beamformer) that does this. She writes ‘permanent’ software (firmware) for controlling the subsystems of the correlator and beamformer.

Our research engineer Mia Baquiran is working on the software that will create a view of the sky using the SKA Low radio telescope.

So how did she get into this space you might ask?

“When I was thinking about what I wanted to do at university I didn’t have that much direction,” Mia said. “Really the only thing that got me excited was the concept of engineering, being able to develop things and understanding how things work.”

She was always interested in physics and robotics appealed too, so she headed for a degree in mechatronics, a field that brings together mechanical engineering, electronics and software.

After finishing her studies at UNSW in 2012 she worked at a small software company, then joined our astronomy and space science research area.

Mia loves problem solving. “There’s always that wonderful moment when you finally find a solution,” she said.

She’s also curiosity-driven. “I like the idea that I can learn something new every day,” she said. “Engineering is constantly changing, so you have to become a lifelong learner.”

“I do enjoy the opportunity to learn from people who are more experienced than me, and that’s definitely well-facilitated in CSIRO.”

Because the correlator and beamformer project is international Mia has had the opportunity to visit the Netherlands to work with colleagues there.

The SKA will give radio astronomers a view of the past a million years after the Big Bang, when the universe first evolving to what is referred to as the “cosmic dawn”.

But what’s in store for Mia in her future?

“I’d like to continue in electronics and FPGA (field programmable gate array) design,” she said.

“Ideally I’d like to continue in radio astronomy, because we’re in a special position being in Australia, where it’s one of the fields that we’re world leaders in.”

Find out more about how CSIRO is helping to bring the Square Kilometre Array to life.

Stem Education Coalition

CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency and one of the largest and most diverse research agencies in the world.

## From astrobites: “Detecting Cosmic Sound using the Square Kilometer Array”

Astrobites

Jan 18, 2017
Joshua Kerrigan

Authors: Francisco Villaescuse-Navarro, David Alonso, and Matteo Viel
First Author’s Institution: Osservatorio Astronomico di Trieste, INAF

Status: Published in MNRAS, [open access]

You may be familiar with the tagline from the movie Alien, “In space, no one can hear you scream”, but what if I told you on cosmological scales there is somewhat of an exception? During the earliest periods of the universe, cosmic forces led to a phenomenon that would be analogous to sound. In today’s bite, we will see how astronomers plan to detect these oscillations.

Cosmological Sound or Baryon Acoustic Oscillations

The competing forces of gravity and radiation pressure, caused fluctuations in the densities of galaxies and the Intergalactic Medium (IGM), resulting in periodic dense and under-dense regions of space. The oscillations in density are what we refer to as Baryon Acoustic Oscillations (BAOs). They provide a standard ruler for cosmological scales comparable to how supernovae are used as standard candles, and therefore can be very useful for constraining cosmological parameters.

How to detect Ancient Sound

The Square Kilometer Array (SKA) is one of the most ambitious, if not the most ambitious radio telescope arrays ever proposed.

SKA

It will cover the radio bandwidth of 50 MHz to 14 GHz by utilizing several different antenna designs and have a square kilometer of collecting area. Today’s paper only concerns the Phase 1 mid to high frequency (350 MHz to 14 GHz) array of the SKA, known as SKA1-Mid.

Detection of BAOs can be accomplished by a large scale mapping of unresolved emission from neutral hydrogen (HI), also known as the 21cm emission (for its wavelength). HI can give us this ability to map out huge swaths of space, as it is the most abundant element in the universe and exists everywhere. However it’s not as simple as using a radio telescope and pointing towards the sky. Galactic and extragalactic foregrounds that are extremely bright can overpower the BAO signal and there is also the issue of the instrument’s response (how the receiver sees a signal) and noise. To determine the feasibility of detecting BAOs using SKA1-Mid with this technique, the authors turn to simulation. They simulate a cosmological HI signal and galactic/extragalactic foregrounds, as if they were observed by the proposed SKA1-Mid in single dish mode for intensity mapping. There were then 3 versions of the final simulations to compare, one with just the cosmological HI signal, the HI signal + instrument noise, and the HI signal + foregrounds + instrument noise.

Some wiggle room for BAOs

Figure 1: Measurements of a simulation (Red) with only the HI cosmological signal. It can be seen that the models with BAOs (Blue) closely follow the measurements of the HI signal, but the real test is whether the SKA1-Mid can detect the BAO signal through foregrounds and noise.

The authors report a difficulty in accurately pinning down a BAO detection at low (z~0.6) and high (z~2.5) redshifts. At low redshifts a detection is limited by a weak BAO signal, while the high redshift region is limited by the telescope beam size smearing out the signal and reducing the signal to noise ratio. In Fig. 1 the cosmological HI signal (free of noise or foregrounds) was sampled and fit to 2 models, a BAO and non-BAO model. In that case, a very clear detection could be technically possible. They go on to show that when including foregrounds and instrument response, the number of simulations with clear detections over redshift begin to drop. The highest redshift bin closest to the end of reionization at z=2.5, shows a decline to 75% of simulations with a clear BAO detection.

These results point out that a potential BAO detection for the SKA1 could be right around the corner, lending support to previous BAO measurements by the Sloan Digital Sky Survey and WiggleZ. We are certainly entering an exciting era of radio astronomy and cosmology. These new instruments have the ability to give us a wealth of new information on BAOs, fast radio bursts, the epoch of reionization and the cosmic dark ages.

Stem Education Coalition

What do we do?

Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.

Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

## From icrar: “Australian Desert Telescope Views Sky in Radio Technicolor”

10.28.16

Dr Natasha Hurley-Walker (Curtin University, ICRAR)
E: nhw@icrar.org
M: +61 426 192 677

Associate Professor Randall Wayth (Curtin University, ICRAR, CAASTRO)
E: randall.wayth@icrar.org
M: +61 418 282 359

Pete Wheeler, Media Contact, ICRAR
E: pete.wheeler@icrar.org
M: +61 423 982 018

Tamara Hunter, Media Contact, Curtin University
E: tamara.hunter@curtin.edu.au
M: +61 (08) 9266 3353

A ‘radio colour’ view of the sky above a ‘tile’ of the Murchison Widefield Array radio telescope, located in outback Western Australia. The Milky Way is visible as a band across the sky and the dots beyond are some of the 300,000 galaxies observed by the telescope for the GLEAM survey. Red indicates the lowest frequencies, green the middle frequencies and blue the highest frequencies. Credit: Radio image by Natasha Hurley-Walker (ICRAR/Curtin) and the GLEAM Team. MWA tile and landscape by Dr John Goldsmith / Celestial Visions.

A telescope located deep in the West Australian outback has shown what the Universe would look like if human eyes could see radio waves.

Published today in the Monthly Notices of the Royal Astronomical Society, the GaLactic and Extragalactic All-sky MWA, or ‘GLEAM’ survey, has produced a catalogue of 300,000 galaxies observed by the Murchison Widefield Array (MWA), a $50 million radio telescope located at a remote site northeast of Geraldton. Lead author Dr Natasha Hurley-Walker, from Curtin University and the International Centre for Radio Astronomy Research (ICRAR), said this is the first radio survey to image the sky in such amazing technicolour. “The human eye sees by comparing brightness in three different primary colours – red, green and blue,” Dr Hurley-Walker said. “GLEAM does rather better than that, viewing the sky in 20 primary colours. “That’s much better than we humans can manage, and it even beats the very best in the animal kingdom, the mantis shrimp, which can see 12 different primary colours,” she said. GLEAM is a large-scale, high-resolution survey of the radio sky observed at frequencies from 70 to 230 MHz, observing radio waves that have been travelling through space—some for billions of years. “Our team are using this survey to find out what happens when clusters of galaxies collide,” Dr Hurley-Walker said. “We’re also able to see the remnants of explosions from the most ancient stars in our galaxy, and find the first and last gasps of supermassive black holes.” MWA Director Associate Professor Randall Wayth, from Curtin University and ICRAR, said GLEAM is one of the biggest radio surveys of the sky ever assembled. “The area surveyed is enormous,” he said. “Large sky surveys like this are extremely valuable to scientists and they’re used across many areas of astrophysics, often in ways the original researchers could never have imagined,” Associate Professor Wayth said. Completing the GLEAM survey with the MWA is a big step on the path to SKA-low, the low frequency part of the international Square Kilometre Array (SKA) radio telescope to be built in Australia in the coming years. “It’s a significant achievement for the MWA telescope and the team of researchers that have worked on the GLEAM survey,” Associate Professor Wayth said. The MWA The Murchison Widefield Array (MWA) is a low frequency radio telescope located at the Murchison Radio-astronomy Observatory in Western Australia’s Mid West. The MWA observes radio waves with frequencies between 70 and 320 MHz and was the first of the three Square Kilometre Array (SKA) precursors to be completed. A consortium of 13 partner institutions from four countries (Australia, USA, India and New Zealand) has financed the development, construction, commissioning and operations of the facility. Since commencing operations in mid 2013 the consortium has grown to include new partners from Canada and Japan. Key science for the MWA ranges from the search for redshifted HI signals from the Epoch of Reionisation to wide-field searches for transient and variable objects (including pulsars and Fast Radio Bursts), wide-field Galactic and extra-galactic surveys, and solar and heliospheric science. The SKA The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, led by SKA Organisation based at the Jodrell Bank Observatory near Manchester, England. Co-located primarily in South Africa and Western Australia, the SKA will be a collection of hundreds of thousands of radio antennas with a combined collecting area equivalent to approximately one million square metres, or one square kilometre. 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. See the full article here . Please help promote STEM in your local schools. Stem Education Coalition ICRAR is an equal joint venture between Curtin University and The University of Western Australia with funding support from the State Government of Western Australia. The Centre’s headquarters are located at UWA, with research nodes at both UWA and the Curtin Institute for Radio Astronomy (CIRA). ICRAR has strong support from the government of Australia and is working closely with industry and the astronomy community, including CSIRO and the Australian Telescope National Facility, iVEC, and the international SKA Project Office (SPO), based in the UK. ICRAR is: Playing a key role in the international Square Kilometre Array (SKA) project, the world’s biggest ground-based telescope array. Attracting some of the world’s leading researchers in radio astronomy, who will also contribute to national and international scientific and technical programs for SKA and ASKAP. Creating a collaborative environment for scientists and engineers to engage and work with industry to produce studies, prototypes and systems linked to the overall scientific success of the SKA, MWA and ASKAP. A Small part of the Murchison Widefield Array Enhancing Australia’s position in the international SKA program by contributing to the development process for the SKA in scientific, technological and operational areas. Promoting scientific, technical, commercial and educational opportunities through public outreach, educational material, training students and collaborative developments with national and international educational organisations. Establishing and maintaining a pool of emerging and top-level scientists and technologists in the disciplines related to radio astronomy through appointments and training. Making world-class contributions to SKA science, with emphasis on the signature science themes associated with surveys for neutral hydrogen and variable (transient) radio sources. Making world-class contributions to SKA capability with respect to developments in the areas of Data Intensive Science and support for the Murchison Radio-astronomy Observatory. • #### richardmitnick 12:54 pm on October 18, 2016 Permalink | Reply Tags: Astronomy ( 5,586 ), Basic Research ( 7,846 ), NATURE ( 89 ), Radio Astronomy ( 342 ), SKA - Square Kilometre Array, University of the Western Cape ## From Nature: “A beacon in the bush becomes an astronomy powerhouse” 13 October 2016 Linda Nordling Afripics / Alamy Stock Photo The architects of South Africa’s apartheid regime never meant for the University of the Western Cape (UWC) on the outskirts of Cape Town to excel at anything. Created in 1960 as a ‘bush college’ to provide black South Africans with limited training, it was not expected to compete with the country’s well-resourced research universities. Its squat buildings were erected far from the city’s wealthy shopping malls, leafy parks and pristine beaches. While the legacy of apartheid looms large in many of South Africa’s social and economic structures, the UWC is not defined by its past. Since the fall of the regime in 1994, the university has established an impressive research record, increasing its articles in Thomson Reuters’ Web of Science database from 31 that year to 657 in 2015, a rise of more than 2000%. In 2014 the university ranked fifth in South Africa for the number of staff holding PhDs — joining the country’s historically ‘white’ institutions in that measure. But, it’s in physical sciences that UWC really punches above its weight compared to South Africa’s elite institutions. The university’s contribution to physical science research in the index, measured by weighted fractional count (WFC), more than doubled between 2012 and 2015. Meanwhile, the University of Cape Town, with its century-long history of academic excellence and sterling research record, saw its WFC in physical science fall slightly over the same time. Astronomical ambitions UWC’s rise in the index is largely due to publications in astronomy, says Roy Maartens, the head of the physics department’s astronomy research group. Maartens returned from the UK to South Africa, his home country, in 2011 to take up UWC’s new chair in radio astronomy. The position was part of the government’s push to boost the country’s chances of winning its bid to host the Square Kilometre Array, a giant radio telescope. And South Africa won. The majority of the telescope, which will comprise thousands of radio antennae spread across a vast area, including countries further north in Africa, will be built in South Africa’s central Karoo semi-desert. The growth of UWC’s astronomy group over the past decade, from none to 6 staff, 15 postdoctoral researchers and 13 postgraduate students today, has been backed by national investments in the SKA. The UWC group is leading efforts to turn the SKA into a state-of-the-art cosmology experiment, probing the structure of dark energy and testing Einstein’s general theory of relativity. Maartens also made UWC history a few years ago when he became the first researcher at the institution to be awarded an A1 rating by the country’s National Research Foundation. The accolade comes with modest funding for the department, but the main impact is symbolic because it is only given to researchers judged to be global leaders in their fields, says Reggie Madjoe, a materials science professor at the university. That, and getting the department a decent coffee machine. “We used to make do with instant, but now with all the famous scientists visiting we need to be able to offer something better,” he says. To Madjoe and others like him, who could only study at UWC, the achievements of the university’s faculty offer great personal satisfaction. “I have to pinch myself,” he says. To this day UWC’s students are mostly non-white, but this makes its academic achievements all the more vital for the future of South Africa, Madjoe says. “We are shaking off the shackles of history. This is a place for everybody, a place for quality, a place to grow,” he says. Maarten believes this is just the beginning for UWC and its astronomy group. When a precursor of the SKA, MeerKAT, comes online next year it will be the world’s most powerful radio telescope until the SKA is built, says Maartens. SKA Meerkat telescope, South African design UWC researchers will use MeerKAT to study galaxy populations and their evolution. “It presents a fantastic opportunity. Our success so far is nice but we have bigger fish to fry,” he says. However, both of Maarten and Madjoe acknowledge the university may face tough times ahead. Last year, violent protests suspended classes at campuses all over the country, with students demanding an end to tuition fees. At the UWC campus students burnt buildings. The government has estimated the cost of vandalism nationwide at more than R600 million (US$43m)

As the 2016 academic year draws to a close, violence has erupted again. There are widespread concerns that extended unrest will threaten research at the country’s universities. Projects such as the SKA, which are of high national priority, are giving UWC astronomy a buffer for now, says Maartens.

Stem Education Coalition

Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

## From SKA via Science Business: “Square Kilometre Array prepares for the ultimate big data challenge”

SKA

22 September 2016
Éanna Kelly

The world’s most powerful radio telescope will collect more information each day than the entire internet. Major advances in computing are required to handle this data, but it can be done, says Bernie Fanaroff, strategic advisor for the SKA

The Square Kilometre Array (SKA), the world’s most powerful telescope, will be ready from day one to gather an unprecedented volume of data from the sky, even if the supporting technical infrastructure is yet to be built.

“We’ll be ready – the technology is getting there,” Bernie Fanaroff, strategic advisor for the most expensive and sensitive radio astronomy project in the world, told Science|Business.

Construction of the SKA is due to begin in 2018 and finish sometime in the middle of the next decade. Data acquisition will begin in 2020, requiring a level of processing power and data management know-how that outstretches current capabilities.

Astronomers estimate that the project will generate 35,000-DVDs-worth of data every second. This is equivalent to “the whole world wide web every day,” said Fanaroff.

The project is investing in machine learning and artificial intelligence software tools to enable the data analysis. In advance of construction of the vast telescope – which will consist of some 250,000 radio antennas split between sites in Australia and South Africa – SKA already employs more than 400 engineers and technicians in infrastructure, fibre optics and data collection.

The project is also working with IBM, which recently opened a new R&D centre in Johannesburg, on a new supercomputer. SKA will have two supercomputers to process its data, one based in Cape Town and one in Perth, Australia.

Recently, elements of the software under development were tested on the world’s second fastest supercomputer, the Tianhe-2, located in the National Supercomputer Centre in Guangzhou, China. It is estimated a supercomputer with three times the power of Tianhe-2 will need to be built in the next decade to cope with all the SKA data.

In addition to the analysis, the project requires large off-site data warehouses. These will house storage devices custom-built in South Africa. “There were too many bells and whistles with the stuff commercial providers were offering us. It was far too expensive, so we’ve designed our own servers which are cheaper,” said Fanaroff.

Fanaroff was formerly director of SKA, retiring at the end of 2015, but remaining as a strategic advisor to the project. He was in Brussels this week to explore how African institutions could gain access to the European Commission’s new Europe-wide science cloud, tentatively scheduled to go live in 2020.

Ten countries are members of the SKA, which has its headquarters at Manchester University’s Jodrell Bank Observatory, home of the world’s third largest fully-steerable radio telescope. The bulk of SKA’s funding has come from South Africa, Australia and the UK.

Currently its legal status is as a British registered company, but Fanaroff says the plan is to create an intergovernmental arrangement similar to CERN. “The project needs a treaty to lock in funding,” he said.

Early success

On SKA’s website is a list of five untold secrets of the cosmos, which the telescope will explore. These include how the very first stars and galaxies formed just after the Big Bang.

However, Fanaroff, believes the Eureka moment will be something nobody could have imagined. “It’ll make its name, like every telescope does, by discovering an unknown, unknown,” he said.

A first taste of the SKA’s potential arrived in July through the MeerKAT telescope, which will form part of the SKA. MeerKAT will eventually consist of 64 dishes, but the power of the 16 already installed has surpassed Fanaroff’s expectations.

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

The telescope revealed over a thousand previously unknown galaxies. “Two things were remarkable: when we switched it on, people told us it was going to take a long time to work. But it collected very good images from day one. Also, our radio receivers worked four times better than specified,” he said. Some 500 scientists have already booked time on the array.

Researchers with the Breakthrough Listen project, a search for intelligent life funded by Russian billionaire Yuri Milner, would also like a slot, Fanaroff said. Their hunt is exciting and a good example of the sort of bold mission for which SKA will be built. “It’s high-risk, high-reward territory. If you search for aliens and you find nothing, you end your career with no publications. But on the other hand you could be involved in one of the biggest discoveries ever,” said Fanaroff.

Golden age

SKA has helped put South Africa’s scientific establishment in the shop window says Fanaroff, referring to the recent Nature Index, which indicates the country’s scientists are publishing record levels of high-quality research, mostly in astronomy. “It’s the start of a golden age,” Fanaroff predicted.

Not that the SKA does not have its critics. With so much public funding going to the telescope, “Some scientists were a little bit bitter at the beginning,” Fanaroff said. “But that has faded with the global interest from science and industry we’re attracting. The SKA can go on to be a platform for all science in Africa, not just astronomy.”

Stem Education Coalition

SKA Murchison Wide Field Array

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.

## From AARNet: “Building the Square Kilometre Array”

AARNet

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AARNet is among the Australian participants in the global Square Kilometre Array project

The Square Kilometre Array (SKA) project is an ambitious global scientific and engineering project to build the world’s largest most sensitive telescope co-located in remote desert regions of southern Africa and Western Australia. The project is currently in the design and pre-construction phase. Australia and New Zealand collaborated to establish the SKA candidate site in Western Australia and also to build the Australian SKA Pathfinder (ASKAP) telescope now located there.

When the SKA is operational, hundreds of thousands of antennas will hugely increase the ability of astronomers to explore the far reaches of the universe and address mysteries around dark energy, gravity and life elsewhere.

Watch this video produced by the Australian Government Department of Industry for an explanation about the project and the role Australia plays:

You can also learn all about the SKA project at the SKA Organisation website.

More than 250 scientists and engineers from 18 countries and nearly 100 institutions, universities and industry will be involved in ‘work packages’ for different elements of the design. Australian industry and research institutes will participate in seven of the eleven work packages, with AARNet working with CSIRO in Signal and Data Transport (including synchronisation) (SaDT).

Expanding the network to meet the needs of the SKA

To enable Australia’s participation in the SKA project, AARNet expanded its network across the Nullabor, from Adelaide to Perth and on to the Murchison Radio Observatory (MRO), the future home of the SKA in remote outback Western Australia.

The newly deployed terrestrial network is capable of transmission speeds of up to 8 Terabits per second (Tbps). The network expansion is a component of the National Research Network (NRN) Project, an initiative of the Department of Innovation, Industry, Science and Research, funded from the Education Investment Fund under the Super Science (Future Industries)

Connecting the SKA precursor telescopes at the MRO

To develop technologies for the SKA, two precursor telescopes, the Australian SKA Pathfinder (ASKAP) and the Murchison Widefield Array (MWA), have been built and are now operating at the MRO. AARNet Interconnects the telescopes at the MRO with the computer processing required for extracting useful information from the signals. Fast reliable research network connectivity is critical for processing data generated from the new radio telescopes.

The Australian SKA Pathfinder (ASKAP) is an innovative new radio telescope consisting of 36 identical 12-metre wide dish antennas. Plans are in place to add 60 more dishes to the telescope in the SKA’s first phase. The ASKAP uses revolutionary Phased Array Feed (PAF) technology, developed in Australia by CSIRO and others, which enables each dish to survey the sky with a much wider field of view. The volume of data generated by the PAFs and low frequency receivers will be substantial.

CSIRO and AARNet worked together to connect the ASKAP antennas to the AARNet network. New optical fibres were laid between Geraldton and ASKAP, connecting to the new Geraldton-Perth link constructed by Nextgen Networks for the federal government-funded Regional Backbone Blackspots Program. This enables ASKAP to connect directly via a high-capacity link to the Pawsey supercomputing facilities in Perth.

The Murchison Widefield Array (MWA) is a revolutionary static low-frequency telescope that can be shared by observers studying different parts of the sky at the same time.

SKA Murchison Widefield Array, in Western Australia

Knowledge gained from the MWA will contribute to the development of the low-frequency component of the SKA to be built in Phase two.

AARNet and CSIRO collaborated to deliver a transmission network for the MWA. The network is installed on fibre optic infrastructure constructed by AARNet for the CSIRO and by Nextgen Networks for the federal government-funded Regional Backbone Blackspots Program.

AARNet is providing the network services for the transmission of the data between the MWA sensors and the Pawsey High Performance Computing Centre for SKA Science, located 800kms away in Perth.

The network is scalable to support the needs of the MWA now and into future early phases of the SKA.

Stem Education Coalition

AARNet provides critical infrastructure for driving innovation in today’s knowledge-based economy

Australia’s Academic and Research Network (AARNet) is a national resource – a National Research and Education Network (NREN). AARNet provides unique information communications technology capabilities to enable Australian education and research institutions to collaborate with each other and their international peer communities.

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