2014 Australian Frontiers of Science - poster abstracts

Exploring 4 billion years of galaxy evolution with ASKAP

Dr James Allison
CSIRO Astronomy and Space Science

Hydrogen is the most abundant element in the Universe and a vital ingredient in the formation of new stars and in feeding supermassive black holes at the centres of massive galaxies. However, until now, the hydrogen content of the distant Universe has remained largely unexplored for a vast period of cosmic history. At radio wavelengths we have been limited by the sensitivity of existing telescopes and contamination from terrestrial radio-frequency interference. Using a new radio telescope—the Australian Square Kilometre Array Pathfi nder (ASKAP)—and its excellent radio-frequency environment, we can now survey the adolescent Universe. Here I present results from a hydrogen survey of distant galaxies using the six-antenna ASKAP prototype. By pointing the telescope towards a young radio galaxy, we have discovered clouds of cold atomic hydrogen, which are drifting in front of the active nucleus and absorbing the radio waves emitted from powerful jets of plasma. Furthermore, the radio spectrum is 304 MHz wide, allowing us to search over a range of lookback times from 4 to 8 billion years ago. This has allows us to place constraints on the cosmological hydrogen density during this period.

Live fast and die young

Dr Yanett Contreras
Australia Telescope National Facility

How stars form is a fundamental question in astrophysics, the answer to which has ramifi cations for the evolution of galaxies, the formation of planets, and ultimately life itself. Listed as one of the 10 big questions in the Australian astronomy Decadal Plan mid-term review, our understanding of how stars form has progressed considerably in recent years and will be revolutionized by the next generation of large telescopes. My current research involves an observational study of the earliest stages of star formation. By combining multi-wavelength data, using both ground-based and space-based observatories, single dishes and interferometers, I am studying how the most massive stars are born. With more than eight times the mass of our sun, these high-mass stars ‘live fast and die young’ and have a profound impact on the ecology of our Galaxy. Here I present some of the main scientifi c results of my research.

Astronomy outreach in the tourism sector

Mr Mike Dalley
Ayers Rock Resort

Ayers Rock Resort and the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO) bring professional astronomy to the public of Australia and the world. Free-choice learning areas are important for the public to outreach, learn and engage in astronomy outside a formal environment. Ayers Rock Resort, in partnership with CAASTRO, have created a new level of professional, free-choice astronomy outreach under the beautiful Central Australian sky. Located only 19 kilometres away from the iconic Ayers Rock, the resort offers high-level astronomy tours. This year, the resort has partnered with CAASTRO to ensure that the astronomy outreach continues to consist of the highest possible standard. Visiting resident astronomers sent by CAASTRO give support to resort staff. Together, they operate nightly tours, such as the famous Sounds of Silence dinner in the desert, and Outback Sky astronomy tours. During the day, the resident astronomers have the opportunity to interact with guests on a one-on-one basis and showcase themselves as they talk about their latest research and where they are based.

Making a splash with the dish: surveying star formation and hidden gas in the milky way

Dr Joanne Dawson
Macquarie University and CSIRO Astronomy and Space Science

The Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) is a new survey with the iconic Parkes 64 metre radio telescope, which tackles two aspects of the outstanding question ‘How do galaxies convert their gas into stars?’ By targeting the radio-frequency emission and absorption from OH molecules in our Milky Way Galaxy, SPLASH is embarking on a hunt for the ‘dark interstellar medium’—a missing link in the evolutionary sequence linking diffuse interstellar gas to dense, cold and dusty star-forming clouds. Further along the evolutionary timeline, SPLASH is also probing deeper than ever before into the Milky Way’s disk to detect the sharp, bright radio spectral lines (masers) that are a signature of newly-forming high-mass stars. Now in the fi nal stages of data processing, the project is beginning to provide new information on the physics and evolution of the interstellar medium, on the structure of our Milky Way, and on the star formation activity within it. This information promises to remain an important legacy dataset for the astronomical community.

A sodium laser guide star facility for the anu/eos space debris tracking adaptive optics demonstrator

Ms Céline d’Orgeville
The Australian National University

Laser guide star adaptive optics (LGS AO) is a technique used to restore space-like imaging conditions for ground-based optical systems by correcting atmospheric turbulence disturbances in real-time. When applied to sharpening the infra-red laser beam used by space debris laser tracking stations, adaptive optics have the potential to enhance the tracking performance and overall station effi ciency by enabling tracking of smaller and more distant debris. The Adaptive Optics group at The Australian National University (ANU) Research School of Astronomy and Astrophysics have teamed up with EOS Space Systems to equip the EOS laser space debris tracking station, located at the ANU Mount Stromlo Observatory, with an adaptive optics demonstrator. This project is a joint project whereby ANU provides LGS AO expertise and EOS provides space debris tracking and laser expertise. While the adaptive optics bench itself is developed mostly by the ANU, the laser guide star facility is a more collaborative effort that uses expertise from both the ANU and EOS teams.

An algorithm for background and noise estimation

Dr Paul Hancock
Curtin University

In the era of big data we are no longer able to hand-curate all the catalogues and images that come from all-sky surveys. As such, we must rely on automated processes to produce high-quality (complete, reliable and accurate) descriptions of the sky. I have developed a source-fi nding algorithm, Aegean, which creates high-quality catalogues from radio images. In this poster, I demonstrate the need for an accurate measure of the background and noise properties of an image. I present an algorithm for background and noise estimation (BANE), that is able to generate accurate maps of the background and noise properties of an input image. It can generate these maps in a fraction of the time of more traditional methods.

Cosmic fountains reveal the birth and death of stars

Dr Lisa Harvey-Smith
CSIRO Astronomy and Space Science

Water masers are very bright sources of cosmic radio emission that are generated when collisions occur in molecular gas. They are commonly found in regions surrounding young massive star formation and old stars that are rapidly turning into planetary nebulae. The study of water masers is extremely useful because the nature of the emission allows astronomers to measure the structure and motion of gas in these regions. Our team has used multifrequency astronomical data to study ten Galactic water masers that have an extremely high (200 to 400 kilometres per second) spread in radial velocity, indicating the presence of very high-velocity outfl ows emanating from stars. These masers were selected from a large survey of molecular gas that was undertaken using the Mopra radio telescope. The masers discovered in this survey were later re-observed at higher resolution using the Australia Telescope Compact Array in order to pinpoint their exact positions on the sky. In this poster, I present images of these fascinating sources, discuss the impact of this study on our understanding of masers as signposts of stellar evolution, and suggest future work.

Tera-scale astronomical data analysis and visualisation

Dr Amr Hassan
Swinburne University of Technology

Upcoming and future astronomy research facilities are moving astronomy into a new era where largescale all-sky surveys, massive numerical simulations, massive databases of astronomical objects, and large international collaborations are the key for future scientifi c discoveries. These resources will fundamentally change the way astronomers deal with their data and pose a serious challenge for current data analysis and visualisation tools. To address these challenges and to enable knowledge discovery in this new era, we designed and built the tera-scale interactive visualisation and data analysis framework, GraphTIVA. GraphTIVA is a framework to interactively volume-render three-dimensional data cubes using distributed ray-casting and volume bricking over a cluster of workstations powered by one or more graphics processing units (GPUs) and a multi-core central processing unit (CPU). I will discuss the key technical aspects of GraphTIVA’s design. I will also discuss a new rendering mode that enables GraphTIVA to be deployed on the CAVE2 at Monash University, Australia. This is a highly immersive environment of 84 million pixels combined with head-tracking, which provides a powerful platform that offers scientists more opportunities to achieve one-to-one mapping between their data and the output pixels, while still retaining context.

Australian astronomy decadal plan—wg3.3 industry group review

Professor Carole Jackson
Curtin University

In the new decadal planning round, WG3.3 was charged with reviewing industry engagement and providing a direction for the next decade (2016– 2025). In this review we summarise the fi ndings of this panel and how they may impact on our efforts in the coming 10 years.

Gravitational waves from neutron stars

Dr Paul Lasky
Monash University

Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) will begin listening to the Universe’s gravitational waves in 2015, potentially opening a new window on the Universe as early as 2016–17. In this poster, I will present ongoing work to understand various gravitational wave emission mechanisms from neutron stars. This includes magnetic fi eld instabilities, superfl uid turbulence and hydrodynamical instabilities in newly born stars. I will also present ongoing data analysis efforts to detect these gravitational waves using LIGO.

Dark matter in the cosmic context

Dr Katie Mack
University of Melbourne

Dark matter forms the foundation for all cosmic structure. Its effects on ordinary matter are primarily gravitational, but most theories suggest that dark matter particle physics might infl uence the gas in its surroundings. In this poster, I show how dark matter’s particle interactions might have altered the evolution of the fi rst stars and galaxies.

Astrophysical transients, and why should we care about them?

Dr Jean-Pierre Macquart
Curtin Institute of Radio Astronomy

Short-timescale transients are associated with the highest energy density events in the Universe, whose emission allows us to probe new physics well beyond that accessible here on Earth. In this poster, I will describe how recent discoveries in this fi eld, particularly the discovery of fast radio bursts at cosmological distances, stand to transform our understanding of the matter and energy content of the Universe itself.

Galactic archaeology with the galah survey

Dr Sarah Martell
University of New South Wales

The Galactic Archaeology with HERMES (GALAH) survey is the most ambitious Galactic archaeology project in progress. In a six-year observing program, our team will take high-resolution optical spectra of one million stars in the Milky Way—an order of magnitude more than competing projects. From these spectra we will determine stellar parameters and abundances for up to 29 elements per star. With this information, we will investigate the Galactic history of star formation, chemical enrichment, stellar migration and minor galaxy mergers.

A comprehensive radio survey for black holes in globular clusters

Dr James Miller-Jones
Curtin University

Globular clusters are dense groupings of hundreds of thousands of stars within a volume of just a few cubic parsecs. Early in the lifetime of the cluster, hundreds of stellar-mass black holes are formed as the most massive stars exhaust their nuclear fuel and undergo catastrophic collapse. The high stellar densities in globular clusters imply frequent close interactions between the black holes and the stars of the cluster, allowing the black holes to acquire companion stars from which they can accrete matter. We can identify and study these black holes via the X-rays emitted by the infalling matter, and the radio waves from the jets launched close to the black hole. Since black holes have a higher ratio of radio to X-ray emission than other classes of accreting objects, deep radio surveys provide an effi cient way to detect quiescent black holes. Our group has recently used this technique to great effect, identifying four new candidate black holes in Galactic globular clusters. We are now conducting a comprehensive radio survey of all nearby globular clusters, aiming to determine the prevalence of black holes in globular clusters, and to measure their mass function.

Widefield imaging algorithms for the australian square kilometre array pathfinder

Dr Daniel Mitchell
CSIRO Astronomy and Space Science

The Australian Square Kilometre Array Pathfi nder (ASKAP) telescope is a radio array that is in the fi nal stages of construction on the Australian Square Kilometre Array site, the Murchison Radio-astronomy Observatory. Each of the ASKAP antennas sees the sky through a phased array feed, an innovative CSIRO system that expands the natural fi eld of view of the telescope from around one square degree to more than 30 square degrees. While ASKAP is a world-leading instrument for high-speed surveys of the radio sky, the wide fi eld of view and enormous associated data rates present some signifi cant computational challenges. This poster gives an overview of the imaging challenges, and solutions that have been developed to address them.

Hydrogen in the universe

Dr Vanessa Moss
University of Sydney/CSIRO Astronomy and Space Science

Hydrogen is the most fundamental and the most abundant element, comprising around 75% of the baryonic mass of the Universe. Its presence determines and drives the evolution of galaxies and the formation of stars, both in the nearby Universe and at distant cosmological times. My research in radio astronomy has revolved around hydrogen in its most basic form: atomic, neutral hydrogen. The spectral line produced by the spin-fl ip transition of hydrogen allows us to trace emission within our own Galaxy, the Milky Way, and absorption in galaxies that existed billions of years ago, shedding light on how this critical star-forming fuel shapes its host galaxies. Using the Galactic All-sky Survey from the 64-metre Parkes Radio Telescope to study gas in our Galaxy and the state-of-the-art Australian Square Kilometre Array Pathfi nder to investigate absorbed hydrogen in far-away galaxies, we can bring together a new understanding of our Universe and its gas over billions of years.

Lessons from bicep2

Dr David Parkinson
The University of Queensland

The recent announcement of detection of large-angle primordial B-mode polarisation of the cosmic microwave background (CMB) by the BICEP2 experiment earlier this year caused considerable stir in the cosmology community, due to the possibility of the signal being generated by gravitational waves. Despite the fact that the signifi cance of these results may have been overstated, especially in light of more realistic estimation of foreground contamination, the existence for the fi rst time of a B-mode signal raises important questions about the correct way that a joint CMB temperature-polarisation analysis should be conducted. In particular, the tension between Planck and BICEP2 seems to drive a very blue-tilted tensor spectrum, which would be contrary to the infl ation prediction. Here, I discuss the role, correct parameterisation, prior range and pivot scale play when considering a spectrum of primordial tensors, and the effect that increasing dust amplitude will have on the results.

Simulating star formation

Dr Daniel Price
Monash University

This poster will present a brief overview of the star formation process, the techniques we use to simulate it on supercomputers, and the algorithms our team has developed at Monash in order to simulate the rich physics involved.

The cosmic microwave background

Dr Christian Reichardt
University of Melbourne

The cosmic microwave background (CMB) is revolutionizing our understanding of the Universe. The CMB is the strongest single piece of evidence that we live in a geometrically fl at Universe, dominated by non-baryonic cold dark matter and dark energy. Many outstanding questions remain around this basic framework: Did infl ation occur, and what physics was responsible for it? What are the neutrino masses? Are there new particle species that we can detect cosmologically? Remarkably, the CMB can shed light on all of these questions. I will discuss the planned Simons Array experiment, an array of three telescopes that will measure CMB polarisation at three frequencies across 80 per cent of the sky. The fi rst telescope will have fi rst light in 2015, with all three telescopes taking data by mid-2016. In conjunction with measurements of the baryon acoustic oscillation feature or Hubble constant, the Simons Array should measure the sum of the neutrino to ~ 18 meV (1 sigma). The Simons Array will also dramatically improve constraints on the infl ationary gravity wave background, reducing the uncertainties by a factor of ten compared to the Planck satellite.

Inferring explosion properties of type i supernovae

Dr Richard Scalzo
The Australian National University

This poster outlines a fl exible, economical Bayesian framework for inferring explosion properties (including ejected mass and explosion energy) of type I supernovae, which are powered by radioactive decay of nickel-56 at and after maximum light. The method uses a semi-analytic model of the bolometric light curve as the likelihood, and incorporates internal constraints on the explosion physics common to well-explored progenitor scenarios as priors. The method has been validated for Type Ia supernovae on synthetic light curves from contemporary numerical simulations of supernova explosions. Applications to real Type Ia supernova data show that the progenitors must span a range of masses at explosion, and that the ejecta mass correlates strongly with the light curve width used to standardize Type Ia supernova distance measurements in cosmology. Future work includes development of a set of priors and internal constraints appropriate to massive star explosions, and inclusion of other energy sources, such as shock interaction with circumstellar material or magnetic spin-down of a neutron star.

Data-intensive quasar microlensing in the survey era of astronomy

Mr Georgios Vernardos
Swinburne University of Technology

Quasar microlensing is a unique probe of quasar structure, from the broad emission line region down to the accretion disc and the supermassive black hole. Moreover, it can be used to study the mass distribution of the galaxy-lens and perform measurements of Hubble’s constant. So far, only single, or small collections, of lensed quasars have been studied using microlensing techniques due to the observational and computational challenges involved. However, this is about to change due to the imminent discoveries by the upcoming all-sky survey facilities (e.g. LSST, the Large Synoptic Survey Telescope). I will present results, data, and tools from the GPU-Enabled High-Resolution MicroLensing parameter survey (GERLUMPH). In particular, how our e-research infrastructure, namely database and web interface to terabyte-sized microlensing simulations, complemented by advanced e-tools for an end-to-end online analysis of lensed systems, can accelerate the rate of scientifi c discovery. As regular monitoring of thousands of new microlensed quasars is expected, such an online resource would dramatically speed up the consistent and systematic study of large collections of these systems, using just a web browser at the user end.

The skymapper southern survey

Dr Christian Wolf
The Australian National University

The Australian National University’s SkyMapper Telescope started in 2014 to map the entire southern sky and will produce not only an image of the sky in six colours, but also a database with 50 million celestial objects. This huge resource allows the study of the structure and evolution of the Milky Way, as well as that of millions of other galaxies. Interpreting such large datasets relies on data mining and machine learning methods such as supervised classifi cation, photometric distance estimation and search for rare and unusual objects. This project will identify millions of stars in the sky that belong to our Milky Way and facilitate follow-up studies of Galactic structure and archaeology. It will also create the largest-ever sample of galaxies—with high-quality photometric distance measurements with up to 10 million galaxies out to a few billion light years— and lay the groundwork for follow-up studies of their evolution with cosmic time. Possible follow-up includes studies of how stellar mass in galaxies builds up over time and how galaxies transform between different types. In addition, the TAIPAN project, which is Australia’s largest detailed spectroscopic survey of galaxies and aims to commence in 2016, will build on this work.

The radio galaxy zoo project

Dr Ivy Wong
International Centre for Radio Astronomy Research

Our team presents the early results from the Radio Galaxy Zoo project—an online citizen science project that asks its participants to help identify the host galaxy that is associated with the observed radio synchrotron emission from supernovas or supermassive black holes (typically 10–100 million times the mass of the Sun). As the black hole radio emission can be spatially offset from the host galaxies, have unusual morphologies and be separated by quite some distance, visual identifi cation of these sources is still the most effective method of identifying the host galaxies. Currently, Radio Galaxy Zoo hosts over 170 000 radio sources and provides the participant with the ability to transition between a radio image and the overlapping infra-red image that shows the stars in the galaxies. In its fi rst nine months of operation, we have made reliable identifi cations of 12 489 host galaxies and we have found that these galaxies have a very high dust content.

© 2024 Australian Academy of Science