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Curtin University
Curtin Institute of Radio Astronomy

Research

Curtin's Institute of Radio Astronomy (CIRA) offers relevant, practical and forward-thinking postgraduate research ready to advance your career in astronomy, space science, technology, physics and/or engineering. CIRA is led by world-renowned experts in radio astronomy. We are heavily involved with the Murchison Widefield Array (MWA), SKA pre-construction design and development and are a major partner in both the International Centre for Radio Astronomy Research (ICRAR) and CAASTRO.

3rd year projects

We welcome enquiries from students keen to do their 3rd year project on a topic within Astrophysics. Please refer to the PhD, Master & Honours projects list (below) as a guide and contact the relevant CIRA supervisor(s) to develop a suitable 3rd year project. Once you have decided on a project and have found a supervisor who is prepared to take you on, then email the name of your project and your project supervisor to the project coordinator, Alec Duncan. If you wish to do a project which is on a topic not listed please contact a supervisor in your area of interest. Further details on 3rd year projects can be found here: http://physics.curtin.edu.au/courses/projects.cfm

PhD, Masters and Honours research topics available now

We welcome enquiries from well-qualified applicants to develop excellent research proposals as part of their formal application to study at Curtin University. To be eligible to apply you must have a strong background in physics, ICT or electrical engineering, good communication skills (including excellent English language, both written and spoken) and be ambitious to complete a first-rate higher degree at our Institute. All potential applicants to Curtin University should consult future students for details on admission, funding and course details.

Below we list the projects on offer for commencement in 2015/2016. The complete set can also be downloaded.

Supervisor: Dr Ramesh Bhat (ramesh.bhat@curtin.edu.au)
Co-supervisors include: Drs Steven Tremblay, Stephen Ord, Simon Johnston (CSIRO)

Project Suitability: PhD > Research Field: Time-Domain Astronomy

In 2013, the Parkes team conducting a large sky survey for pulsars announced the discovery of an exciting and new class of transient sources – Fast Radio Bursts (FRBs; Thornton et al. 2013). Given their extremely large dispersion measures, these bursts are thought to originate from cosmological distances, of the order of several Giga-parsecs. They represent potential new probes for measuring the baryonic content and the magnetic field of the Intergalactic Medium. The physics governing the origin of these energetic bursts is currently unknown, although a large flurry of theoretical ideas have now been postulated including some exotic possibilities involving compact objects, dark matter and even cosmic strings. As with high-energy phenomena such as gamma-ray bursts, effective localization and follow-ups with other instruments and at multiple wavelengths hold the key to uncover their origin and underlying physics.

Follow-up investigations of FRBs pose significant technical challenges given their short durations, thus necessitating real-time processing and rapid communication of alerts. With the advent of a capability at Parkes to be able detect them in real-time (Petroff et al. 2015), it is now possible to undertake effective follow-ups. The newly-operational Murchison Widefield Array (MWA), a low-frequency radio telescope in Western Australia with a large field-of-view (~300 – 600 deg2) and electronic steering capability, would make an ideal instrument to conduct rapid follow-ups of FRBs that are detected by other radio telescopes such as Parkes and Molonglo. Such rapid follow up will be crucial for characterizing the spectrum and scattering characteristics of FRBs, thereby helping to uncover the as-yet unknown emission process.

This PhD project will focus on developing a mode for the MWA to receive and respond to the trigger alerts from instruments such as Parkes, and conducting efficient FRB follow-ups with MWA, both fast and slow, for prompt emission as well as potential afterglows. The MWA will also provide a much better localization than that is possible with Parkes or Molonglo. The project will involve close collaboration with CSIRO Astronomy and Space Science and Swinburne Centre for Astrophysics.

Detection PlotFigure 1: Preliminary tomographic view of the polar emission region of PSR B0809+74 from the work of Maan, Deshpande et al. (2013), obtained by stacking maps at four different frequencies within the 117-330 MHz band of the multi-band receiver developed for the Green Bank telescope. The project will focus on suitable pulsars in the southern sky, using the MWA, GMRT and Parkes telescopes for a wide frequency coverage.

Supervisor: Dr Ramesh Bhat (ramesh.bhat@curtin.edu.au)
Co-supervisors include: Drs Steven Tremblay, Stephen Ord, Avinash Deshpande (RRI)

Project Suitability: PhD > Research Field: Observational Pulsar Astronomy

More than four decades since their discovery, the physics governing coherent emission of radio signals from pulsars remains largely elusive. Pulsar radio emission is known to exhibit a rich and diverse phenomenology, e.g. phenomena such "sub- pulse drifting", "pulse nulling" and "mode changing" to name a few, when observations are performed at high sensitivity and time resolution. The rich diversity and complexity in observations and the extreme physical conditions that prevail in he pulsar magnetospheres pose significant challenges to theorists and physicists in understanding the underlying emission mechanism.

Of the various pulsar emission phenomena, "sub-pulse drifting", i.e. organised marching of finer structures (i.e. sub-pulses) within the pulsar emission window, offers an elegant and powerful means to potentially uncover the complex physical processes occurring in the pulsar magnetospheres. Investigation of this however requires sensitive, high-quality observations to be performed at high time resolutions to discern the details in pulsar emission, and hence a detailed study is limited to a handful of bright pulsars. The newly-operational Murchison Widefield Array (MWA) in WA is the low-frequency Pre- cursor to the Square Kilometre Array (SKA), and has recently gained the ability to perform high time resolution science.

This PhD project will focus on undertaking in-depth, systematic investigations of a sample of suitably selected pulsars in the southern hemisphere that exhibit the sub-pulse drifting phenomenon. Besides undertaking a detailed study at multiple different frequencies within the MWA band, it will also involve undertaking observations with the GMRT and Parkes telescopes for higher frequency coverage. The analysis will involve the application of cartographic transform techniques pioneered by Deshpande and Rankin (1999) to construct the pulsar emission spots within the magnetosphere, to map out the polar cap emission regions at different altitudes, thereby enabling he unique prospects of performing a three-dimensional tomography. The project is particularly suitable for students with a strong background in physics, analytical skills and an aptitude for software development, simulations and data modelling.

Figure 1: Preliminary tomographic view of the polar emission region of PSR B0809+74 from the work of Maan, Deshpande et al. (2013), obtained by stacking maps at four different frequencies within the 117-330 MHz band of the multi-band receiver developed for the Green Bank telescope. The project will focus on suitable pulsars in the southern sky, using the MWA, GMRT and Parkes telescopes for a wide frequency coverage.

Supervisor: Dr Ramesh Bhat (ramesh.bhat@curtin.edu.au)
Co-supervisors include: Drs Steven Tremblay, Stephen Ord, George Hobbs (CSIRO)

Project Suitability: PhD > Research Field: Observational Pulsar Astronomy

Direct detection of gravitational waves is one of the key goals of modern astrophysics and offers exciting prospects of opening up a brand new window with which to study the Universe. Pulsar timing array (PTA) experiments around the world that exploit the clock-like stability of fast-spinning (millisecond) radio pulsars are aimed at detecting low-frequency gravitational waves in the nano- Hertz frequency range. This incredibly challenging goal involves developing an in-depth understanding of the various systematics in pulsar timing data that may arise from the instrumentation, the pulsar emission process and the effects of the interstellar medium (ISM), as well as developing suitable methods to correct for them.

Among the most prominent systematics in long-term pulsar timing data are the effects caused by the ISM on pulsar signals, including dispersion, scattering and scintillation. These are difficult to characterize well at timing frequencies (typically above 1 GHz), but are better discernible (and hence measurable) at low radio frequencies, given their steep scaling with frequency. Observing timing array pulsars with the MWA thus offers great advantages for accurate characterization of important ISM effects.

This PhD project will focus on the effective use of MWA to support the Parkes pulsar timing array (PPTA) project – currently the world leader in high-precision timing efforts around the world. For instance, the MWA's large field-of-view can be exploited to observe multiple pulsars from a single pointing. The project will involve developing optimal strategies for observing PPTA pulsars with the MWA, their data collection and analysis, interpretation of ISM effects and their impact on timing precision, and developing methods to correct for them in pulsar timing data. Aside from its significance for the PPTA project, low-frequency observations of millisecond pulsars will be interesting in their own right. The project will involve close collaboration with CSIRO Astronomy and Space Science (CASS) team led by Drs Manchester and Hobbs.

weather trackingFigure 1: Dynamic spectrum of pulse intensity from MWA observations of the timing-array millisecond pulsar PSR J0437-4715 (from Bhat et al. 2014). The modulations and patterns seen in pulse intensity arise from multipath propagation of the pulsar signal through the intervening interstellar medium. The MWA's 80-300 MHz operating frequency range is well suited for detailed characterisations of such propagation phenomena in the ISM toward all PPTA pulsars.

Supervisor: Dr Peter Curran (peter.curran@curtin.edu.au)
Co-supervisors: Dr James Miller-Jones, Dr Robert Soria

Project Suitability: PhD > Research Field: Accretion Physics

Black holes are powerful cosmic engines that convert the potential energy of infalling mass into energy and radiation visibleover the entire electromagnetic spectrum. Much of the energy is lost through the event horizon of the black hole but some of it forms powerful relativistic jets with speeds very close to the speedof light. How the output power is related to the rate at which mass falls onto the black hole and how the power evolves over time is of critical importance in understanding how black holes, of all masses, transfer energy back into their host galaxies. This energy can influence the formation and evolution of galaxies and eventhe structure of the Universe as a whole. While supermassive black holes at the centres of galaxies develop on timescales of millennia, stellar mass black holes evolve on the much more human-accessible timescale of months or days and are hence ideal for studying how black holes evolve over time.

This project aims to address the evolution of the fundamental properties of the black hole as an engine. It involves observations of stellar mass black holes that, powered by a greatly increased level of in-falling mass, enter extremely active states of outburst. During these outbursts, there is a dramatic increase in the amount of light emitted at all wavelengths, which allows us study them with Earth-based radio and optical telescopes, as well as orbital X-ray satellites. As part of an international team of astronomers, you will analyse data from such international facilities, including the precursors to the new generation SKA telescope (based in Australia and South Africa). Additionally, a possible computational component would assess how the local structure of the magnetic fields around the black hole might affect the observed properties of light. Through this project you will address how black holes redistribute energy and how that energy interacts with the surrounding galaxy, thus shedding light on how black holes affect galaxy evolution.

Supervisor: Dr Tom Franzen (thomas.franzen@curtin.edu.au)
Co-supervisor: Prof Carole Jackson

Project Suitability: PhD > Research Field: Radio Astronomy

Present astrophysical theories hold that all sufficiently large galaxies host supermassive black holes at their centres. For reasons not entirely understood, these supermassive black holes sometimes spew out jets of energetic particles. In the most powerful radio galaxies, the period of jet activity is rather short (less than ~108 years) compared with the lifetime of the parent galaxy (~1010 years). The jets produce enormous lobes of radioemission which expand over time. These lobes are one of the two major components of a typical radio galaxy, the other being its active galactic nucleus (AGN). The figure on the bottom left shows a radio image of the radio galaxy 3C348 superimposed on an optical image.

There is a growing body of evidence that AGN activity can involve multiple episodes. The most striking examples of recurrent AGN activity in radio galaxies are the double-double or triple-double radio sources which contain two or three pairs of distinct lobes on opposite sides of the host galaxy. The figure on the bottom right shows an example of a double-double radio galaxy imaged by the Giant Metrewave Radio Telescope (GMRT) in India. Although the typical duty cycle of AGN activity (the relative lengths of the radio- active and radio quiescent phases) is relatively well constrained in distant, powerful radio galaxies, this is not the case in more nearby, low-luminosity radio galaxies. A key question is therefore how the typical duty cycle varies with radio luminosity and cosmic epoch.

This project will use radio data spanning several orders of magnitude in frequency, including the new 70-230 MHz GLEAM survey, to identify sources which are ‘restarted' radio galaxies, showing signs of AGN activity at high frequency together with lobe activity at low frequency, and will combine this with optical data to determine their prevalence as a function of radio luminosity and redshift. This will provide important new information about the lifetimes and duty cycles of radio galaxies. The PhD student will have the opportunity to conduct follow-up observations using radio and optical telescopes in Australia.

weather trackingFalse colour image of radio galaxy 3C348: Optical in white/yellow, radio in red. Credit: NASA, ESA, S. Baum, C. O'Dea, R. Perley, W. Cotton and the Hubble Heritage Team. weather trackingFigure 2: Image of the double-double radio galaxy J1453+3308 at 334 MHz reproduced from Konar et al. (2006). Two pairs of lobes appear on either side of the host galaxy; the age of the outer lobes is ~50 Myr and that of the inner lobes is ~2 Myr. The physical size of the radio galaxy is ~1.3 Mpc

Supervisor: Dr Tom Franzen (thomas.franzen@curtin.edu.au)
Co-supervisor: Prof Carole Jackson

Project Suitability: Masters > Research Field: Radio Astronomy

This project will explore the nature of the faint extragalactic radio source population selected at 20 GHz, using observations made with the Australia Telescope Compact Array (ATCA). Early radio surveys were conducted at low frequencies due to the technology available at the time, e.g. the 3C survey at 178 MHz. With advances in technology and the need for higher resolution surveys, studies moved to higher frequencies. As a result, source counts, particularly at 1.4 GHz, are well determined to fluxdensities below 0.1mJy. The faint population at higher frequencies (tens of GHz), however, has been much less widely studied due to the increased time required to survey an area of sky to an equivalent depth at these frequencies.

High-frequency surveys have the potential to shed light on possible new classes of sources. They also provide further insights into the physics of sources detected in lower frequency surveys, for example giving information on the break frequencies marking the transition from optically thick to optically thin regimes, and on any high-frequency steepening due to electron ageing.

In 2009, the ATCA was used to carry out a very deep survey of a small patch of the radio sky at 20GHz (Franzen et al. 2014), detecting a total of 85 extragalactic radio sources. This project will use optical and infrared data to study these sources in more detail. This will help us learn more about the energetic events which are associated with massive black holes at the centres of galaxies.

Supervisor: Dr Paul Hancock (paul.hancock@curtin.edu.au)
Co-supervisors: Dr Natasha Hurley-Walker, Dr Andrew Walsh

Project Suitability: PhD, Masters, Honours > Research Field: Radio Astronomy, Astrophysics

The interstellar medium (ISM) is a diffuse gas that permeates our entire galaxy. The ISM is extremely important in astrophysics because it acts as an intermediary between events that happen on stellar scales and those that we see on galactic scales. Stars are born from and will return to the ISM over their million- to billion-year life cycles. One of the main components of the ISM is the warm ionized medium (WIM) - an ionized gas at a temperature of 8,000K, which makes up as much as 50% of the ISM. All of the light that travels to us from outside our Galaxy must travel through the WIM, which will cause changes in the light that we see. The WIM can change the polarization state of light through Faraday rotation, and will bend light rays to cause focusing and defocusing events like scintillation. This (Interstellar) scintillation (ISS) is similar to what you see at night when you see a bright star twinkling, however at radio frequencies the twinkling is less intense and a lot slower. By identifying extragalactic radio sources that are exhibiting scintillation, we can determine how the WIM is changing along that particular line of sight. These changes are due to turbulent motions in the WIM, and have been measured before. So far we are only able to determine the average global properties of the WIM because our lines of sight are spaced far apart.

Curtin University operates the Murchison Widefield Array (MWA) which is a low frequency radio array, and a precursor to the SKA. The MWA telescope has a very large field of view (>600deg2) and is able to create sensitive images in just a few minutes. This speed and field of view mean that it will be easy to image many thousands of extragalactic radio sources in a few minutes, and to do so on a weekly basis. With such a large population of sources to draw from, we will be able to identify ISS in thousands of radio sources. We will then use these sources to understand not just the global properties of the WIM, but how these properties change throughout the Galaxy. This will be the first time that such a map will be made and it will greatly increase our ability to understand the ISM and the vital role it plays in the evolution of both stars and our Galaxy.

This project will study the WIM by looking for scintillation in extragalactic radio sources that are observed with the MWA. We currently have an observing program in place that will observe a large section of the sky on a weekly basis, as well as a data reduction pipeline that will automate most of the processing stages. You will work with an international team of astronomers help identify scintillating sources within the large data sets that will be produced. You will learn many of the skills vital to modern astronomy including: processing and visualizing very large data sets, working on super-computing facilities, working effectively within a collaboration, and communicating results in written and oral form on a national and international level.

refractive scintillationFigure 1: Refractive scintillation occurs when radio wave from a distant source (left) pass through an lumpy ionised gas cloud (middle). gas clouds distort the wave front and cause a distorted view of the object (right). As the gas clouds move with respect to the distant source, the scintillation pattern changes, making it appear that the background radio source is changing in brightness. This scintillation effect can be used to determine the properties of the otherwise invisible gas clouds.

Supervisor: Prof Carole Jackson (carole.jackson@curtin.edu.au)
Co-supervisors: Prof Simon Driver (UWA), Dr Nick Seymour

Project Suitability: PhD, Masters > Research Field: Radio Astronomy

A relatively small fraction of all galaxies are classical 'radio loud' galaxies – a class of Active Galaxies – at any particular epoch. The onset of AGN activity could be a single or recurrent phase of otherwise fairly 'normal' galaxy lifecycles. Understanding the conditions, environment and hosts of the powerful radio-loud galaxies is not well determined; moreover there are a number of apparent sub-classes (populations) of these radio-loud galaxies (compact, peaked, head-tail, etc) that complicate any simple analyses.

To investigate populations of radio galaxies we need multi- wavelength data, most obviously to obtain distance and spectral information. Intensive and absorbing follow-up of small radio- selected samples has resulted in some very significant complete samples. However, understanding the populations in detail is challenging – not least because bright radio sources can be embedded in distant and often otherwise quiescent galaxies.

Across the whole electromagnetic spectrum the quality and quantity of survey data has progressed with increasingly powerful instrumentation. Notably the quality of radio survey data has blossomed in the past decade. The MWA is currently surveying the southern sky at 70-230 MHz (GLEAM) and will provide a catalogue of extragalactic sources unbiased by beaming effects which often plague interpretation of radio data above ~ 1 GHz. Combining GLEAM data with that from other radio surveys such as NVSS and SUMSS provides sufficient resolution to confidently cross-match with other wavelength data.

In this research we will use spectroscopic, photometric and a wide range of multi-wavelength data to investigate the hosts of powerful, relatively local (z < 0.3) galaxies. The multi-wavelength data will be obtained primarily from the 5 regions of the GAMA database (http://www.gama-survey.org and Driver et al (2009) http://arxiv.org/abs/1009.0614) with possible follow-up observations of selected objects or classes to secure the conclusions of this research. Data from the MWA Galactic & Extragalactic all- sky survey (GLEAM) survey will be cross-matched with to select a complete sample of powerful radio galaxies. Using the well-calibrated GAMA data we will then investigate whether there are any physical differences between the low and high-excitation radio galaxies, including their host types, star formation rates, abundances and environment.

Supervisor: Prof Carole Jackson (carole.jackson@curtin.edu.au)
Co-supervisors: Prof Jasper Wall (UBC), Dr Nick Seymour

Project Suitability: PhD, Masters > Research Field: Radio Astronomy

The Murchison Widefield Array (MWA) is a new radio telescope in Western Australia operating between 70 and 240 MHz – a waveband relatively unexplored until the recent advent of the MWA and its northern hemisphere counterpart, LOFAR.

To investigate populations of radio galaxies and quasars we need complete samples. Obtaining these relies on multi-wavelength data, most obviously to obtain distance and spectral information. Intensive and absorbing follow-up of small samples of radio- selected objects has resulted in some very significant complete samples but the number of sources in each remains statistically tiny. However, identifying any complete sample is challenging – not least because bright radio sources can be embedded in distant and otherwise quiescent galaxies.

Across the whole electromagnetic spectrum the quality and quantity of survey data has progressed with increasingly powerful instrumentation. Not least, the quality of radio survey data has blossomed in the past decade or so, with surveys such as NVSS and SUMSS providing all-sky coverage around 1 GHz, with sufficient resolution to confidently cross-match with other wavelength data. When coupled with other (particularly high resolution) radio-, IR- and optical data the resultant radio-selected source samples provide significant new data to untangle the physical nature of radio galaxies and quasars.

This project will start with the sample of the brightest MWA sources and seek to identify the most powerful radio sources selected at low radio frequencies; this sample will provide new insights into these extreme sources unbiased by relativistic beaming effects and obscuration.

CygnusFigure 1: Cygnus A – a powerful radio galaxy at z=0.06 discovered by Grote Reber in 1939. luminosityFigure2: from Wall et al (2005) the luminosity – volume plane for a complete set of powerful, flat-spectrum quasars selectedat 2.7 GHz.

Supervisor: Jean-Pierre Macquart ( j.macquart@curtin.edu.au)
Co-Supervisor: Dr Cathryn Trott

Project Suitability: PhD > Research Field: Astrophysical Transients and Cosmology

The dynamics of the Universe in which we live — from the motions and clustering of galaxies to the very expansion of the Universe itself — is dominated by the gravitational influence of dark matter (26%) and the pressure exerted by dark energy (70%). The measured influence due to ordinary baryonic matter, the stuff of which people, planets and stars are made, is a paltry 4%. However, over the past decade, astronomers have come to the embarrassing realisation that there are serious problems in even accounting for this baryonic material, the only component of the Universe whose identity is known. Censuses of the baryons in the present-day Universe can account for no more than a third of the inferred amount.

Where are these baryons? Cosmological simulations indicate that they most likely reside not in galaxies or stars, but in an extremelytenuous Intergalactic Medium (IGM) (Cen & Ostriker 1999). The IGM, believed to be 99.999% ionized, is extremely difficult to detect. It is undetectable in absorption lines. Emission lines of hydrogen, the most common species present in the Universe, are present but because the IGM is so diffuse, with a maximum likely number density of only ~10-7cm-3, these lines are almost impossible to detect. Other heavier elements, present in trace abundances, produce even weaker emission and absorption lines.

There is, however, an entirely different way to probe the IGM. A newly-discovered type of radio transient, Fast Radio Bursts (FRBs), emits radiation that is subject to scattering by small-scale density perturbations in the IGM. FRBs are extremely bright millisecond-duration events (see Figure 1) whose radiation emanates from bursts at cosmological distances, up to several Gpc away! The IGM alters FRB radiation by smearing their bright flashes in time, so that the pulse width increases at longer wavelengths. Furthermore, the radiation also arrives later at low frequencies, at fact that we can use to directly measure the total column of electrons that the radiation has propagated through in the IGM. The enormous prospects for using FRBs as precision cosmological tools are explained in a number of articles, including a popular review (https://www.sciencenews.org/article/searching-distant- signals) and a detailed scientific article (Macquart et al. 2015, http://arxiv.org/abs/1501.07535).

Outline

In this project you will use advanced analytic skills to use FRBs to weigh the baryonic matter in our Universe and to determine its structure on cosmic scales. You will interpret observations of FRB dispersion and scattering properties to construct a model for the cosmic web of structure and physical conditions of the baryonic component of the IGM (see Figure 2).

You will directly address two of the most pressing fundamental problems in modern astrophysics and cosmology. You will determine both (i) the location of the missing baryons in our Universe and (ii) directly measure the effect of feedback in galaxy formation. Most dark matter in the Universe is found within massive galaxy halos, but most baryonic matter is outside this scale (~100kpc). Since baryonic matter is more sensitive than dark matter to star formation and AGN feedback in galaxies, the baryon distribution is very sensitive to the way in which astrophysical processes distribute this matter in a process known as feedback. The location of these missing baryons thus reveals how the feedback operates. The distribution of dispersion measures is sensitive to the locations of these baryons, and can determine whether they lie within the virial radius of galaxy halos, or whether they lie further out in an intra-halo medium.

For those more theoretically inclined, the project can be extended to include cosmological simulations of the distribution of baryonic matter near galaxies to directly determine the predictions of various galaxy feedback scenarios. This project is ideally suited to someone who enjoys answering the big questions about our Cosmos. You will be at the forefront of cosmological and astronomical research involving the rapidly-developing field of FRBs.

intergalactic plasmaFigure 1: Intergalactic plasma slows down low-frequency radio waves more than higher frequencies, so they arrive at the telescope later. The figure above also shows that the pulse width increases to lower frequencies, demonstrating that the pulse is subject to scattering by turbulence in the Intergalactic Medium. (Credit: Duncan Lorimer et al.). cosmological simulationsFigure 2: Numerical cosmological simulations trace the gravitational influence of dark matter in the Universe very well, but a key uncertain element in these simulations is the distribution of the baryonic matter. Where do the baryons reside? (Credit: Klaus Dolag).

Supervisor: Dr James Miller-Jones ( james.miller-jones@curtin.edu.au)

Project Suitability: PhD > Research Field: Accretion Physics

By combining the signals from antennas spread across the globe, Very Long Baseline Interferometry (VLBI) provides the highest resolution images available to astronomers, resolving structures on angular scales of less than on milliarcsecond - as small as a person on the Moon. This high angular resolution also enables the measurement of extremely precise positions for astronomical sources. By tracking the position of an astronomical radio source over time, we can measure not only how fast it is moving across the sky (its proper motion), but also the apparent annual wobble imposed by the Earth's motion around the Sun (its parallax).

Matter falling onto a dense compact object, such as a neutron star or a black hole can (under certain conditions) be diverted outwards into fast-moving, collimated, oppositely-directed jets of matter. These jets produce radio emission, which can be detected by VLBI arrays. Unless the rate of mass infall is very high, these jets appear as unresolved, point-like sources, and can be used as ideal astrometric probes, enabling the measurement of the proper motion and parallax of stellar-mass black holes and neutron star systems (X-ray binaries) within our own Milky Way Galaxy.

Black holes and neutron stars form from the deaths of the most massive stars. While neutron stars and some black holes are believed to form in supernova explosions, black holes can also form by direct collapse of a large gas cloud. By measuring the proper motion of a system, we can place constraints on the velocity kick imparted to the black hole when it was formed, and hence on the formation mechanism. By measuring the parallax of a source, we can obtain an accurate, model-independent distance, enabling us to convert observable quantities such as measured flux into physical quantities such as luminosity. Finally, for binary systems in wide orbits, we can trace the orbital motion of the radio- emitting source, enabling us to measure the masses of the sources and the inclination angle of the binary.

In this project, you will use VLBI arrays in Australia, Europe and the USA to conduct astrometric studies of X-ray binary systems, aiming to probe the black hole formation mechanism, probe the relativistic jets from compact objects, determine accurate source distances, and investigate orbital motion where possible.

xray binaryFigure 1: Motion of the black hole X-ray binary V404 Cygni over time (times indicated in years since the first observation). Note the parallax wobble superimposed on the linear motion (from Miller-Jones 2014).

Supervisor: Dr James Miller-Jones ( james.miller-jones@curtin.edu.au)
Co-Supervisors : Dr Peter Curran, Dr Roberto Soria

Project Suitability: PhD > Research Field: Accretion Physics

The release of gravitational potential energy as matter falls onto a compact object such as a black hole or a neutron star powers the most energetic phenomena in the Universe, allowing us to study at higher energies and in stronger gravitational fields than could ever be reproduced in a laboratory here on Earth.

As matter falls onto a black hole, its angular momentum causes it to form a rotating accretion disc around the central object. Depending on the accretion rate, the inner radius of the disc can extend down to the innermost stable circular orbit of the black hole, or it can be truncated a few hundred kilometres out, with the inner regions containing a more vertically-extended, hot, evaporated flow. However, matter does not only flow inwards. Some fraction of the infalling material can be diverted outwards in relativistically-moving, oppositely directed, bipolar jets, or in slower, more massive, equatorial winds. The different geometries of the inflow appear to be associated with these different types of outflow. With multiwavelength observations, we can probe all these different components of the system; jets (the radio through infrared bands), accretion flow (the optical through X-ray band), disc wind (via X-ray absorption lines).

We believe that the same physics governs the behaviour of these stellar-mass compact objects as governs their more massive analogues in the supermassive black holes seen at the centres of galaxies (Active Galactic Nuclei; AGN). However, since stellar-mass objects evolve on much faster timescales (days and weeks rather than millennia), they act as unique probes of the physics governing the accretion and outflow around black holes, providing new insights into their radiative and kinetic feedback that has an impact on cosmological scales.

This project seeks to further our understanding of the connection between inflow and outflow around accreting compact objects. By making comparative observational studies of stellar-mass black hole, neutron star and even white dwarf systems during their sporadic outbursts, we can probe the effect of the depth of the gravitational potential well, and the existence of a stellar surface and a stellar magnetic field on the properties of both the outflowing jets and winds, and on the accretion flow.

black holeFigure 1: A schematic of a black hole accreting matter from a donor star via an accretion disk. Relativistic jets (seen here in red and purple) are launched from the inner regions of the accretion flow.

Supervisor: Dr Stephen Ord (stephen.ord@curtin.edu.au)
Co-supervisors: Dr Ramesh Bhat, Dr Steven Tremblay

Project Suitability: PhD, Masters, Honours > Research Field: Observational Pulsar Astronomy

Radio pulsars are rapidly-rotating, highly-magnetized neutron stars. With almost 2000 now known, observations of pulsars allow the study of a range of astrophysical phenomena, from strong gravity and gravitational waves to interstellar scattering and the equation of state of dense matter.

The newly operational Murchison Widefield Array (MWA), a low- frequency (80-300 MHz) radio telescope recently constructed in Western Australia, provides a wide range of opportunities to perform pulsar observations and surveys. With an extremely wide field of view (30 degrees across at 150 MHz), the MWA will be an excellent facility for detecting transient radio emission. There is a counterpart survey being performed in the northern hemisphere by the LOFAR telescope. The MWA has a unique view of the southern hemisphere and therefore has the opportunity to open a new discovery space (see Figure). There are also opportunities within this research area for software engineers in developing efficient search and candidate excision procedures.

We will be running survey observations for radio pulsars throughout the MWA Operations phase. This program is very compute intensive and offers projects in areas as diverse as data mining and pattern recognition as well as astronomy and astrophysics. The MWA will be especially sensitive to the poorly understood population of intermittent pulsars, and survey programs with interferometers are only beginning to become feasible due to the large computational requirements. There is considerable opportunity for high impact contributions to be made in this field.

pulsarsFigure 1: The filled areas in the figure represent those parts of the sky that have been searched for pulsars by the LOFAR telescope. The MWA is a comparable telescope, but located in the Southern hemisphere, which opens up an entirely new discovery space for a low frequency pulsar and radio transient surveys.

Supervisor: Dr Franz Schlagenhaufer (f.schlagenhaufer@curtin.edu.au) Possible Co-supervisor: Dr Adrian Sutinjo

Project Suitability: PhD, Masters > Research Field: Electrical Engineering, Electromagnetic Propagation

The Square-Kilometre Array (SKA) is an international project to build a radio telescope with unprecedented sensitivity, resolution, and field of view, covering the frequency range between 50 MHz and 20 GHz. The SKA will be divided in several frequency bands, the lowest is known as SKA_LOW (50 MHz-350 MHz) and will be built across Australia and New Zealand. SKA_LOW is expected to consist of hundreds of stations, with hundreds of antenna elements in each station. Most of the stations will be located within 50 km of the core of SKA_LOW at the Murchison Radio- astronomy Observatory (MRO).

To achieve its ground-breaking science goals, electromagnetic interference (EMI) from SKA's own hardware must be tightly controlled. Specifications for electromagnetic radiation from any devices installed at the MRO must be developed based on correct threshold levels that cause interference with radio astronomy observations, and accurate values for the path-loss between sources and antenna elements.

The most critical EMI scenario for SKA_LOW is emission in the frequency range 50 - 350 MHz from sources close to the ground, in a distance of less than 1 km. Reliable propagation models for such a scenario are currently not available, and must be developed and tested.

Analytical considerations and computer simulations will be important tools for this project. It is also expected that all results are substantiated by measurements on site at the MRO. The low frequency aperture array verification system 1 (AAVS1) is constructed as a precursor to SKA_LOW to verify various design parameters, and can also be used as a test platform for EMI characteristics.

The scope of this project is to develop and test propagation models relevant for SKA_LOW, and to investigate whether commonly used threshold levels of ITU Recommendation 769 (Protection criteria used for radio astronomical measurements) need to be revised for this special case.

The student is expected to have some exposure to and/or is willing to acquire backgrounds in antenna arrays, radio astronomy techniques, electromagnetic modelling and measurements, and signal processing. Some field trips to the MRO are to be expected. This project is suitable for an engineering or applied physics student with a career outlook in radio astronomy, telecommunications, or general system level electromagnetic compatibility.

skaFigure 1: SKA_Low antennas installed at the MRO for trial purposes.

Supervisor: Supervisor: Dr Nick Seymour (nick.seymour@curtin.edu.au) Co-supervisor: Dr Rob Sharp (ANU)

Project Suitability: PhD, Masters > Research Field: Radio Astronomy

Obtaining distances, as derived from redshifts, to galaxies is a key prerequisite to studying the evolution of starforming galaxies and the hosts of powerful supermassive black holes across cosmic time. Typically an optical spectrum for each galaxy is required, but this requires a considerable amount of valuable time on 8m-class telescopes. Over the past decade, techniques of estimating the redshifts of large numbers of galaxies from broadband optical and infra-red photometry have been developed. However, such analyses are typically designed for optically selected galaxies and require a large number of photometric bands to be accurate. Radio surveys from the Murchison Widefield Array (MWA: 70-300MHz) and the Australian Square Kilometre Array Pathfinder (ASKAP: 700-1800MHz) will find tens of millions of extra-galactic radio sources many of which will not have decent coverage from optical telescopes.

This project will examine a series of machine learning methods to obtain redshifts based on limited information including kth Nearest Neighbour and Self-Organised Map amongst others. These will be tested against a growing catalogue of known redshifts of radio sources in particular those obtained from the OzDES project (http://www.mso.anu.edu.au/ozdes/). Hence, this project will also be actively involved in a major observational programme on the Anglo-Australian Telescope along with reduction and classification of optical spectra.

Once these methods are well calibrated then even sources with large uncertainties on their distances can be used among the millions of radio sources from MWA and ASKAP to constrain the evolution of the star forming and black hole radio populations. This work will be of key importance in the preparation for deep surveys with the Square Kilometre Array.

mapFigure 1: Example of a Self-Organised Map used to classify radio sources by their morphology (Polsterer et al.2014).

Supervisor: Dr Nick Seymour ( nick.seymour@curtin.edu.au)
Co-supervisor: Dr Stas Shabala (UTas)

Project Suitability: PhD, Masters > Research Field: Radio Astronomy

A key science goal of the Square Kilometre Array (SKA) is to make deep continuum images of the radio Universe in order to trace the history of star formation and black holes across cosmic time. Due to its sensitivity, field of view and the fact that radio emission is not obscured by dust the SKA will make the most accurate measurement of the history of galaxy and black hole growth. To date the extensive modelling of the radio continuum Universe has been based on phenomenological extrapolation of how known radio populations behave with little consideration of the underlying physics or connections to other wavelengths. This project would aim to address these issues by using the state of the art mock galaxy simulations (e.g. the Theoretical Astrophysical Observatory) and radio emission simulations to estimate radio luminosities from star formation and black holes across cosmic time.

This project would cover three key areas:

  1. Refinement and understanding of the physics producing radio emission from star forming galaxies and black holes in order to simulate what different surveys would measure.
  2. Comparison with different surveys, in particular those from the Murchison Widefield Array
  3. (MWA: 70-300MHz) and the Australian Square Kilometre Array Pathfinder (ASKAP: 700-1800MHz)
  4. Simulate how well the SKA will be able to measure galaxy and black hole evolution in order to guide the planning of the SKA Key Science Projects. This is vital step, yet to be undertaken by the community in planning for the SKA.
deep radio surveyFigure 1: A close up of a deep radio survey with the Australia Telescope Compact Array showing the diversity of radio sources.

Supervisor: Dr Nick Seymour ( nick.seymour@curtin.edu.au)
Co-supervisors: Prof Carole Jackson, Dr Jose Afonso (IA, Lisbon University)

Project Suitability: PhD, Masters > Research Field: Radio Astronomy

How did the first super-massive black holes form and grow? There is growing evidence that some of the very first black holes formed very early in the Universe (within the first billion after the Big Bang) and may have been active during the Epoch of Reionisation when all the neutral hydrogen was reionised. How they grow so big, in such a short period, is not yet understood. During active phases, accreting black holes are the most luminous objects in the Universe often producing powerful jets of out-flowing material. These jets produce synchrotron radiation visible at radio wavelengths which far out-shine the host galaxy. Hence, radio surveys are a key tool in finding super-massive black holes in the early Universe.

This project will comprise three parts:

  1. Studying the broadband radio properties of known powerful black holes at high redshift in order to characterise their typical jet emission at these redshifts and to examine the role of jets in their evolution. This part will involve observing, reducing and modelling radio data from facilities such as the Very Large Array and Australia Telescope Compact Array.
  2. Using the all-sky radio surveys from the low-frequency Murchison Widefield Array (MWA: 70-300MHz) and the Australian Square Kilometre Array Pathfinder (ASKAP: 700-1800MHz) to search for the earliest black holes. This part of the project will involve combining data from these two radio telescopes and then follow-up observations of candidate early black holes with powerful optical and IR telescopes.
  3. Targeted low-frequency spectral observations of the highest redshift sources in order to look for absorption due to neutral HI before the Universe has fully reionised. Such observations will complement current on-going efforts by the MWA collaboration to detect and measure the infrared telescopes such as the Very Large Array Telescope and the Atacama Large Millimetre Array via its power-spectrum.

This project will uniquely exploit large area surveys from the MWA and ASKAP and pave the way for future studies with the Square Kilometre Array.

black holeFigure 1: Accurate simulated view of an accretion dish around a black hole as developed for the film Interstellar (James et al. 2015).

Supervisor: Dr Nick Seymour ( nick.seymour@curtin.edu.au)
Co-supervisor: A/Prof Andrew Hopkins (AAO)

Project Suitability: PhD, Masters > Research Field: Radio Astronomy

When, where and how did all the stars in the Universe form? This is a key question in modern astrophysics particularly as we already know that the rate of forming stars was much greater in the past. Current optical and infrared surveys of this energetic process in the early Universe are hamstrung by the small field of view of these telescopes and the effects of dust at these wavelengths. Radio emission can trace both galaxy growth (star formation) and the related super-massive black hole growth, and is impervious to the effects of dust. Furthermore, the next generation of radio telescopes (i.e. the Square Kilometre Array and its pathfinders) will have extremely wide fields of view so will be ideal instruments to trace star formation and black hole activity.

This project will comprise two parts:

  1. Detailed broadband radio studies with the Murchison Widefield Array (MWA: 70-300MHz) and the Australian Square Kilometre Array Pathfinder (ASKAP: 700-1800 MHz) in order to better understand the physics behind radio emission related to star formation. A prime goal will be to determine an accurate conversion of radio luminosity to star formation rate for different galaxies at different redshifts.
  2. Using deep radio observations from Australian Telescope Compact Array and ASKAP to measure the star formation history of the Universe as a function of redshift, stellar mass and environment. The star formation rates will be determined from the new calibration of the conversion from radio luminosity. The results of this work will provide a new insight into galaxy formation and growth, and will constrain semi-analytical models of galaxy evolution.

The results of this work will directly lead to the planning and analysis of this key science goal with the Square Kilometre Array.

star formationFigure 1: Current constraints on the star formation history of the Universe from deep radio surveys (Seymour et al. 2008). The results possible from ASKAP will be hundreds of times more precise.

Supervisor: Dr Adrian Sutinjo ( adrian.sutinjo@curtin.edu.au)
Co-supervisor: Dr Budi Juswardy

Project Suitability: PhD, Masters > Research Field: Electrical Engineering, Radio Astronomy

The Square Kilometre Array (SKA) is an international project to build radio telescope with a combination of unprecedented sensitivity, resolution, and field of view (FoV) covering the frequency range from 50 MHz up to 10 GHz. SKA telescope is divided into several frequency bands, the lowest is known as SKA_LOW (50-350 MHz) and will be built in Australia. SKA_LOW is expected to consist of hundreds of stations with hundreds of antenna elements in each. Most of the stations will be located at the core of SKA_LOW at the Murchison Radio-astronomy Observatory (MRO), within an area of 50 km radius.

As a precursor to SKA_LOW, a low frequency aperture array (LFAA) verification system 1 (AAVS1), envisaged as a small subset of the SKA_LOW, will be constructed at the MRO. The purpose of AAVS1 is to verify various critical design parameters of SKA_LOW using an on-site engineering prototype. Initial efforts in this area have resulted in the construction and characterisation of an experimental array of 16 antennas co-located with the Murchison Widefield Array (MWA).

RF-over-fibre (RFoF) technology is a leading candidate solution for transporting radio frequency (RF) signal from the LFAA front-end, where analogue radio signal is transmitted from the antennas to the central processing facility via fibre optic (FO) cables, as opposed to coaxial cables. The SKA_LOW aims to perform highly sensitive observations. Consequently, impairments accrued in the signal transport chain components such as the RFoF need to be well understood and characterized.

As an example, stability of RFoF modules and the fibre optic cables over time and temperature is a critical in obtaining correct radio astronomy data. Characterisation of parameters such as gain and phase variations due to the thermal exposure of the RFoF modules and FO cable has been performed in the lab and at the MRO. In addition, we expect to further understand of the impact of these parameters to radio telescope calibration and observation. The scope of this project is to further analyse existing field results, develop understanding of RFoF parameters which are relevant to radio astronomy, and devise measurement strategies for characterisation of those parameters.

This project will be associated closely with the work in the low frequency aperture array work for SKA project within the Aperture Array Design Consortium (AADC), in which ICRAR/Curtin is a major player. The student is expected have some exposure to and/or is willing to acquire backgrounds in RF system analysis, radio astronomy techniques, optical communication, and laboratory measurements. Some field trips to the MRO are to be expected. This project is suitable for an engineering or applied physics student with a career outlook in radio astronomy, telecommunications and/or applied physics.

laboratory measurementsFigure 1: Laboratory measurements of RFoF links.

Supervisor: Dr Adrian Sutinjo ( adrian.sutinjo@curtin.edu.au)
Co-supervisor: Dr Randall Wayth

Project Suitability: PhD, Masters > Research Field: Electrical Engineering, Radio Astronomy

The Square Kilometre Array (SKA) is an international project to build radio telescope with a combination of unprecedented sensitivity, resolution, and field of view (FoV) covering the frequency range from 50 MHz up to 10 GHz. SKA telescope is divided into several frequency bands, the lowest is known as SKA_LOW (50-350 MHz) and will be built in Australia. SKA_LOW is expected to consist of hundreds of stations with hundreds of antenna elements in each. Most of the stations will be located at the core of SKA_LOW at the Murchison Radio-astronomy Observatory (MRO), within an area of 50km radius.

As a precursor to SKA_LOW, a low frequency aperture array verification system 1 (AAVS1), envisaged as a small subset of the SKA_LOW, will be constructed at the MRO. The purpose of AAVS1 is to verify various critical design parameters of SKA_LOW using an on-site engineering prototype. Initial efforts in this area have resulted in the construction and characterization of an experimental array of 16 antennas co-located with the Murchison Widefield Array (MWA).

The radio signal received by AAVS1 and SKA_LOW antennas is expected to be transported via Radio- on-Fiber (RFoF) links which allow low-loss long-distance transmission to a digital beamformer. Proper beamforming requires that correct weights be applied to each input. This requires the removal of the effects of the insertion of various RFoF link lengths between the beamformer and the antennas. We refer to this process as instrumental calibration.

Instrumental calibration in the Northern Hemisphere is aided by the presence of two bright and compact radio astronomical sources, CasA and CygA. However, those sources are not easily accessible in the Southern sky. The Southern sky has to contend with many less bright sources and the dominant Galactic noise. The aim of this project is to chart an instrumental calibration strategy for low frequency aperture array for the Southern sky. The AAVS1 in conjunction with the MWA will be used as an experimental test bed for this purpose. Successful outcome of this project is expected to be a major contribution to the SKA_LOW.

This project will be associated closely with the work in the low frequency aperture array work for SKA project within the Aperture Array Design Consortium (AADC), in which ICRAR/Curtin is a major player. The student is expected have some exposure to and/or is willing to acquire backgrounds in phased array antennas, radio astronomy techniques, electromagnetic (EM) modelling and measurements and signal processing. Some field trips to the MRO are to be expected. This project is suitable for an engineering or applied physics student with a career outlook in radio astronomy, telecommunications and/or applied physics.

AAVSIFigure 1: Fully deployed AAVSI at the MRO

Supervisor: Dr Adrian Sutinjo ( adrian.sutinjo@curtin.edu.au)
Co-supervisor: Dr Randall Wayth

Project Suitability: PhD, Masters > Research Field: Electrical Engineering, Radio Astronomy

The Square Kilometre Array (SKA) is an international project to build radio telescope with a combination of unprecedented sensitivity, resolution, and field of view (FoV) covering the frequency range from 50 MHz up to 10 GHz. SKA telescope is divided into several frequency bands, the lowest is known as SKA_LOW (50-350 MHz) and will be built across Australia and New Zealand. SKA_LOW is expected to consist of hundreds of stations with hundreds of antenna elements in each. Most of the stations will be located at the core of SKA_LOW at the Murchison Radio-astronomy Observatory (MRO), within an area of 50 km radius.

As a precursor to SKA_LOW, a low frequency aperture array verification system 1 (AAVS1), envisaged as a small subset of the SKA_LOW, will be constructed at the MRO. The purpose of AAVS1 is to verify various critical design parameters of SKA_LOW using an on-site engineering prototype. Initial efforts in this area have resulted in the construction and characterization of an experimental array of 16 antennas co-located with the Murchison Widefield Array (MWA).

In radio astronomy, polarimetry is the measurement of the state of polarization of astronomical sources. The ability to detect the state of polarization of radio astronomical sources is of great interest as a large amount of astrophysical information is encoded in it. However, radio astronomical instruments themselves are imperfect; they add “instrumental polarization” to the sources in question. Hence, it is critical that the polarization performance and calibration of the LFAA be well understood. ICRAR/Curtin has begun an in-depth investigation into the instrumental polarization of the MWA. Various models with varying levels of complexity are being compared and evaluated. The scope of this project is to refine, implement and test the polarimetric model of the MWA "tile" (an array of 4x4 antennas) to achieve an accurate but computationally efficient and flexible model. This model will be used to facilitate characterization of AAVS through interferometric measurements with the MWA.

This project will be associated closely with the work in the low frequency aperture array work for SKA project within the Aperture Array Design Consortium (AADC), in which ICRAR/Curtin is a major player. The student is expected have some exposure to and/or is willing to acquire backgrounds in phased array antennas, radio astronomy techniques, electromagnetic (EM) modelling and laboratory measurements and signal processing. Some field trips to the MRO are to be expected. This project is suitable for an engineering or applied physics student with a career outlook in radio astronomy, telecommunications and/or applied physics.

MWA tile moduleFigure 1: An MWA tile module in a full wave EM simulator (FEKO).

Supervisor: Dr Steven Tremblay ( steven.tremblay@curtin.edu.au)
Co-supervisor: Dr Stephen Ord, Dr Ramesh Bhat, Dr Simon Johnston (CSIRO)

Project Suitability: PhD, Masters, Honours > Research Field: Pulsars

Pulsars are regularly used as probes to study astrophysical topics ranging from interstellar plasma physics to gravitational wave detection. However much is still unknown about the mechanisms behind the radio wave emission relied heavily upon for these experiments. Pulsars display emission from gamma ray to below UHF radio frequencies. Although pulsar emission in general is extremely regular and the most stable of pulsars are considered nature's most accurate clocks, many pulsars display irregularity in their emission. This behaviour takes various forms. There is a population of pulsars that only emit individual pulses on the time scale of hours (the Rotating Radio Transients). There are many pulsars that generally emit continually but can display a complete cessation of radio emission that lasts from seconds to days (nulling and intermittent pulsars). All pulsars display a variation in intensity from pulse to pulse, but some display individual "giant pulses" of extremely short duration that are typically 100's to 1000's of times brighter than regular pulses.

The Murchison Widefield Array (MWA) is a 128-element low-frequency Square Kilometre Array precursor, which has recently gained the ability to perform high-time resolution science. This project is directed at using this capability in the study of pulsars that display intermittent emission phenomena. This project will encompass a census of pulse-to-pulse variability in the low-frequency pulsar population with the MWA, high frequency coverage will be provided by Parkes Observatory. Followed by direct studies of members of the intermittent pulsar population in an attempt to gain deeper understanding of the pulsar emission mechanism. And investigate the links between these different examples of intermittency over a wide range of timescales. The results of this research will also inform the number and frequency of fast transients detected by the low frequency portion of the Square Kilometre Array.

total powerFigure 1: Total Power.

There are new technical challenges with doing this science at low frequencies. The interstellar medium is turbulent and ionised. Radio waves that propagate through it are scattered and dispersed. Individual pulses are intrinsically narrow, but at low frequencies their width is dominated by the impulse response of the interstellar medium (see Figure showing how an inherently short duration giant pulse is scattered over tens of milliseconds). They carry the imprint of the medium they have traversed, and this project offers the opportunity to apply novel schemes that attempt to remove these propagation effects. Techniques developed at these frequencies, where these effects are strong and easily detected, has great utility at higher frequencies where these effects are still present but are difficult to characterise. The precision of higher frequency measurements is now thought to be dominated by propagation effects and variations in pulse emission properties. Two features of pulsar emission that will be explored in this project.

Supervisor: Dr Cathryn Trott ( cathryn.trott@curtin.edu.au)
Co-supervisor: Dr Randall Wayth

Project Suitability: PhD, Masters > Research Field: Interferometry; Epoch of Reionisation

The primary science goal of the MWA is to perform statistical detection (power spectrum) of the Epoch of Reionisation (EoR) using the redshifted 21cm line of neutral hydrogen to probe changing conditions within the intergalactic medium. SKA-Low is expected to extend this effort to measure a high-precision power spectrum, allowing discrimination between cosmological models of the early Universe, and probing gas physics at early times. A key first step in the construction and testing of SKA-Low is combining the MWA with AAVS (Aperture Array Verification System) antennas to form visibilities between antennas with markedly different design. These antennas view the sky differently, and different information is available from visibilities measured with MWA-MWA baselines, AAVS-MWA baselines, and AAVS-AAVS baselines. Key questions are: How should information from different baselines be optimally combined? What information is available for these different baselines? An extension to this work would be to consider SKA-Low exclusively with dynamically-allocated and variable antenna station sizes.

MWAFigure 1: The MWA currently deployed at the Murchison Radio Astronomy Observatory (MRO).SKA_lowFigure 2: An artist's impression of SKA_Low

Supervisor: Dr Cathryn Trott ( cathryn.trott@curtin.edu.au)
Co-supervisor: Prof Carole Jackson

Project Suitability: PhD, Masters > Research Field: Epoch of Reionisation; Radio Sky Populations

The primary science goal of the MWA is to perform statistical detection (power spectrum) of the Epoch of Reionisation (EoR) using the redshifted 21cm line of neutral hydrogen to probe changing conditions within the intergalactic medium. A major challenge for EoR detection is the presence of bright extragalactic radio galaxies contaminating the Early Universe signal. This project will build a statistical model for the impact of unresolved populations of AGN and star forming galaxies, on EoR science. In particular, it will use existing understanding of these source populations, their clustering on the sky, and spectral properties, to correctly incorporate them into the data analysis. This work will build on current, simplistic models of foreground contaminants. Students with good mathematical and statistical skills, and an interest in extragalactic populations of galaxies, would be well suited to this project. structure of extragalactic radio galaxiesFigure 1: Simple model for structure of extragalactic radio galaxies in the Epoch of Reionisation power spectrum.

Supervisor: Dr Cathryn Trott ( cathryn.trott@curtin.edu.au)
Co-supervisors: Prof Chris Power (UWA), Prof Carole Jackson

Project Suitability: PhD, Masters > Research Field: Epoch of Reionisation; Radio Sky Populations; Simulations

The primary science goal of the MWA is to perform statistical detection (power spectrum) of the Epoch of Reionisation (EoR) using the redshifted 21cm line of neutral hydrogen to probe changing conditions within the intergalactic medium. A major challenge for EoR detection is the presence of bright extragalactic radio galaxies contaminating the Early Universe signal. This project will build a statistical model for these contaminating signals, using the outputs of N-body and semi-numeric simulations. These simulations couple the reionisation source population at high redshift, to the sources of radio contamination at lower redshift (AGN, star forming galaxies), providing a self-consistent model of signal and contaminants. The candidate will explore the range of models derived from these self-consistent models, and compute constraints on high redshift structures given observations at lower redshifts.

Students with good mathematical and statistical skills, and an interest in extragalactic galaxy populations, would be well-suited to this project.

neutral hydrogen brightness temperatureFigure 1: Model for the evolution of neutral hydrogen brightness temperature as a function of redshift, and pictorial representation of the reionisation of the Universe (Pritchard & Loeb 2008).

Supervisor: Dr Cathryn Trott ( cathryn.trott@curtin.edu.au)

Project Suitability: PhD, Masters, Honours > Research Field: Instrument Calibration

Redundant baselines in radio interferometry are those that instantaneously sample the save Fourier mode. For Epoch of Reionisation science, they allow for the most rapid reduction in thermal noise with time, by allowing for coherent combination of the measured visibilities. They also have the advantage of allowing sky- and beam-independent gain calibration of the telescope, and the PAPER array uses redundancy to identify systematic errors in their data. Beyond these applications, redundancy has the ability to provide information about the telescope, by studying the systematic biases measured from nominally-redundant baselines. These tools may become useful for next-generation radio telescopes, such as the extended MWA and SKA-Low, where complicated primary beams make precision science a challenge.

This project will take existing work with redundant baselines as a basis to develop novel tools for understanding the instrument through measurements of redundant visibilities. It will be highly mathematical, and will develop mathematical models for the expected biases from different instrumental effects. The work can then be applied to future instruments to assess their impact.

extended MWAFigure 1: The proposed layout for an extended MWA including two patches of tiles set out in hexagons. tile configurationFigure 2: The detail of the tile configuration in one hexagon showing the regular spacing.

Supervisor: Dr Andrew Walsh ( andrew.walsh@curtin.edu.au)

Project Suitability: PhD > Research Field: Galactic Astronomy

Astrochemistry is the study of the formation and evolution of molecules, ions and radicals in space through the natural processes normally associated with the formation of stars. In interstellar space, only the simplest molecules can exist. But buried deep inside a dark cloud of gas and dust, and gently heated by a nearby newly born star, atoms and simple molecules can undergo reactions to form ever-more complicated molecules. The Holy Grail for astrochemists around the world is to find evidence for naturally occurring amino acids in interstellar space. Amino acids are some of the building blocks for life, so their detection in space will help us understand how life can naturally begin. Glycine is the simplest amino acid and thus the most likely to be detected first, but despite over 30 years of searches has yet to be seen.

Astrochemistry can also be used to help us understand sites of star formation within our Galaxy. The complexity of molecules available can be used as a simple chemical clock to tell us how evolved one region may be. In this project, the focus will be on the star forming region G305, which shows multiple stages of star formation, from the earliest pre-sellar cores to well-developed stars on the main sequence and about to emerge from their natal dust shells.

G305 provides a unique environment to study all these stages in one place, which simplifies observations and allows us to study the interactions between the various sites. However, given the Southern declination of this region, not much work has been done on it. Some early work identified what might be the earliest stage of high mass star formation known (G305SW), showing unusual chemistry. This project will focus on G305SW and its surroundings.

This project will involve utilising telescopes such as the Australia Telescope Compact Array, the MWA, Parkes and ALMA. Both low and high resolution spectral line imaging will be needed to understand the chemistry of G305. This project is designed to align with planning for the SKA and will help place the student appropriately to continue research in future SKA radio astronomy.

infrared imageFigure 1: An infrared image of the G305 star forming region, showing dense gas and dust, traced by extended green emission. These are the sites that harbour the next generation of star formation.

Supervisor: Randall Wayth (r.wayth@curtin.edu.au)
Co-supervisor: Dr Natasha Hurley-Walker

Project Suitability: PhD, Masters > Research Field: Radio Astronomy

The Murchison Widefield Array (MWA) is a low frequency (80-300MHz) radio telescope operating in Western Australia and the only SKA_Low precursor telescope. Its design has many small antennas rather than fewer larger antennas as is typical for radio telescopes working at higher frequencies.

Forming high fidelity images with the MWA can be challenging. The issues include:the very wide field of view of the MWA, the large data volume due to having many antennas, the corrupting effect of the ionosphere, the unusual reception pattern of the antennas (they are fixed on the ground), among others. Processing MWA data can often violate assumptions inherent in conventional radio astronomy data processing software. More accurate techniques are available but often come at a huge computational cost. Because of this, supercomputers are required to process large quantities of MWA data.

This project aims to investigate and develop novel techniques in radio astronomy data processing to improve the performance and/or fidelity of calibration and imaging algorithms, with a focus on MWA and future SKA_Low data. The application of these techniques has the potential to impact the Epoch of Reionisation (EoR) and GLEAM survey science programs of the MWA, which have each collected several PB of raw data.

This project is suited to a student with a strong interest in the fundamentals of radio astronomy and a solid background in computer science, maths and/or physics.

MWA dataFigure 1: Example MWA data before (left) and after (right) improved calibration

Supervisor: Randall Wayth (r.wayth@curtin.edu.au)

Project Suitability: PhD, Masters > Research Field: Radio Astronomy Interference Mitigation

The MWA is a low frequency radio telescope operating between 80 and 300 MHz in at the Murchison Radio-astronomy Observatory (MRO) in Western Australia and is the only precursor telescope to the SKA_Low. Although the MRO is extremely radio quiet, in particular in the FM radio and TV bands where the telescope operates, residual low levels of radio-frequency interference (RFI) have the potential to affect very sensitive experiments, like the Epoch of Reionisation (EoR) key science program.

This project aims to characterise the source of residual low-level RFI in MWA data and to design, build and deploy dedicated monitoring equipment that can be used to identify and subtract this RFI from MWA data.

This project would suit a student with an electrical engineering background with good computing skills and an interest in signal processing.

MWA antenna tileFigure 1: An MWA antenna 'tile'

Supervisor: Randall Wayth (r.wayth@curtin.edu.au)
Co-supervisor: Dr Cathryn Trott

Project Suitability: PhD > Research Field: Epoch of Reionisation

The MWA is a low frequency radio telescope operating between 80 and 300 MHz in Western Australia. One of the key science goals for the MWA is to measure the faint diffuse signal from neutral hydrogen in the early universe – the Epoch of Reionisation (EoR). Measuring the properties of the EoR is currently the greatest goal in observational cosmology. The expected radio signals from the hydrogen, however, are much fainter than those from our Galaxy, hence making a robust measurement challenging. The diffuse polarised radio emission from our Galaxy is generated by the interstellar plasma and magnetic fields.

The expected signal from the EoR evolves with cosmic time as shown in the Figure below. The fluctuations have many angular size scales, which are comparable to the size scales of the diffuse polarised emission. This project aims to understand, quantify and remove the effects of diffuse polarised radio emission on the EoR power spectrum measurement of the MWA. The project will involve understanding how the telescope's response to polarised radio emission couples to the measurement of the EoR and how imperfect subtraction and/or calibration of the polarisation signal will affect the EoR measurements. This project will be essential to the ultimate EoR power spectrum measurement made by the MWA.

This project suits a student with a strong physics and mathematics background, good computing skills and an interest in physics of the early Universe. As an SKA_Low precursor, the results of this MWA project are directly applicable to the future EoR key science program of the SKA.

opacity of the universeFigure 1: A simulation of the opacity of the universe changing with time (time increasing to the right) during the EoR.

Supervisor: Randall Wayth (r.wayth@curtin.edu.au)
Co-supervisor: Dr Natasha Hurley-Walker

Project Suitability: PhD > Research Field: Radio Surveys

The Murchison Widefield Array (MWA) is a low frequency (80-300MHz) radio telescope operating in Western Australia and the only SKA_Low precursor telescope. One of the largest science programs for the MWA is the Galactic and Extragalactic All-sky MWA (GLEAM) survey, which has surveyed the entire visible sky for two years since the MWA commenced operations.

GLEAM has collected vast quantities of data. A large part of the first year of this data has been published as an extragalactic source catalogue. However the second year of this dataset remains to be fully processed.

This project will process the remaining GLEAM data and incorporate it into existing processed data along with making necessary improvements and innovations in the processing pipeline. The resulting multi-year dataset will be the most sensitive survey output from the MWA yet. As well as generating images and catalogues that are widely useful, the student will also undertake a focussed research project of his/her choice that utilises the data. This could include (but is not limited to): transient/variable radio sources, scintillation, the ionosphere and radio source population studies.

The project is well suited to a student with strong computing skills, an interest in gaining a deep understanding of radio astronomy calibration and imaging, and an interest in a science area that can be addressed by data from the GLEAM survey.

An MWA radio image of the LMC and SMCFigure 1: An MWA radio image of the LMC and SMC.

Supervisor: Dr John Morgan (john.morgan@curtin.edu.au)
Co-supervisor: Dr Jean-Pierre Macquart

Project Suitability: PhD, MAsters, Honours > Research Field: Low-Frequency Radio Astronomy

The Murchison Widefield Array (MWA) is a low-frequency radio interferometer unparalleled in its wide field of view and its imaging fidelity. Although a remarkably flexible instrument, its resolution does not exceed 1 arc minute. Determining source size and morphology on much smaller scales (~1 arc second or less) can be a very useful addition to the excellent spectral and arc minute-scale information that the MWA provides us with.

One way to learn about source morphology on arc second scales is via Interplanetary Scintillation (IPS). Sources which have compact components will change rapidly in brightness (on timescales of 0.1s-10s) due to turbulence in the interplanetary medium.

In many ways the MWA is extremely well-suited to this work. Its wide field of view means that IPS can be measured for a very large number of sources in a single observation. Its excellent imaging fidelity means that the scintillation signatures of difference sources can reliably be separated from one another. However a great deal of work remains to be done to realise the full potential of the instrument. The project would require a student with an interest in the technical details of interferometry. Experience in radio astronomy or big data computation would be beneficial. It could be tailored to suit interests in heliospheric physics and/or understanding compact radio sources.

angular distanceFigure 1: The angular size of sources (assumed to be intrinsically compact sources seen through the M31 galaxy as a function of angular distance from the core of M31. Those nearest to the centre appear to be larger. This is thought to be due to "scatter broadening" of the sources by the turbulent ISM of M31.

Supervisor: Dr John Morgan (john.morgan@curtin.edu.au)
Co-supervisor: Dr Jean-Pierre Macquart

Project Suitability: PhD, MAsters > Research Field: High-Resolution Radio Astronomy

The ionised Interstellar Medium (ISM) is an important component of our Galaxy, comprising as much as 50% by volume and 80% by mass of the total ISM. It traces many astrophysical processes, and yet, due to the difficulty of observing it directly (compared with the neutral component, which can be studied via the 21 cm line) it is poorly understood. Very Long Baseline Interferometry (VLBI) observations allow the turbulence in the ionised ISM to be probed along lines of sight by measuring the “scatter broadening'” of intrinsically compact sources. However, there are great difficulties in determining the distribution of the ionised ISM from our position well within the plane: only within 1kpc of the Solar System can complex structure be mapped, allowing correlation with other astrophysical phenomena.

Applying this technique to other galaxies could produce significantly improved results since even a small inclination to the line of sight separates the components of the ISM, greatly increasing the observable information. A pilot study of M31 undertaken a couple of years ago showed very promising results, with strong evidence of the detection of the ionised ISM of a nearby galaxy for the first time. Much deeper VLBI observations of M31 have now been undertaken and await analysis.

Beyond the main goal measuring the ISM of M31 there are further secondary goals that might be achieved with these data. The first is HI absorption towards the brighter background sources, one of which lies right on a neutral filament in the M31 galaxy. The second is determining accurately the brightness M31* across at least 3 epochs in 2012, when it is thought to be much dimmer than expected. Third, the possibility of detecting compact sources that are hosted within M31, such as X-ray binaries.