Research led by OzGrav PhD student Yu Wing Joshua Leeand supervisor Dr Manisha Caleb at the University of Sydney has uncovered the slowest cosmic lighthouse yet – a long-period radio transient – likely a neutron star – spinning once every 6.5 hours. This discovery, found using CSIRO ASKAP radio telescope and published in Nature Astronomy, not only pushes the boundaries of what we thought possible for such objects, which typically rotate very quickly, but also reveals a rare phenomenon: the ability to see radio pulses from both of the star’s magnetic poles.
OzGrav is thrilled to congratulate Distinguished Professor Susan Scott on being awarded the George Szekeres Medal, the Australian Mathematical Society’s most prestigious honour. This award recognises outstanding contributions to the mathematical sciences, cementing Susan’s status as a leader in her field.
The medal was presented by Jessica Purcell, President of the Australian Mathematical Society, during the opening ceremony of the joint meetings of the Australian, American, and New Zealand Mathematical Societies in Auckland.
This historic win marks a series of firsts and milestones:
Susan is the third woman in Australia to receive the medal.
She is the first woman from the Australian National University (ANU) to achieve this recognition.
She is only the second person from ANU ever awarded this honour.
A pioneer in gravitational wave theory and mathematical physics, Susan’s groundbreaking work has influenced the global scientific community and inspired a new generation of researchers.
The George Szekeres Medal, named after the celebrated mathematician, is a testament to Susan’s unwavering dedication to advancing mathematical sciences. Her work embodies the very essence of innovation and excellence.
We are incredibly proud to celebrate this well-deserved recognition of Susan’s remarkable career. Watch the video below where Susan shares her journey and reflections on this significant achievement.
An international study led by astronomers from Swinburne University of Technology and Monash University has created the most detailed maps of gravitational waves across the universe to date.
The study also produced the largest ever galactic-scale gravitational wave detector and found further evidence of a “background” of gravitational waves: invisible yet incredibly fast ripples in space that can help unlock some major mysteries of the universe.
This international effort, conducted with the MeerKAT radio telescope in South Africa, includes three studies published today in Monthly Notices of the Royal Astronomical Society. Together, these works offer new insights into the universe’s most massive black holes, how they shaped the Universe, and the cosmic architecture they left behind.
Lead author for two of the papers and a researcher at OzGrav and Swinburne, Dr Matt Miles, says the research opens new pathways for understanding the universe that we live in.
“Studying the background lets us tune into the echoes of cosmic events across billions of years,” Dr Miles explained. “It reveals how galaxies, and the universe itself, have evolved over time.”
The MeerKAT Pulsar Timing Array, an international experiment which uses the MeerKAT Radio Telescope in South Africa, one of world’s most sensitive and cutting-edge radio telescopes, observes pulsars and times them to nanosecond precision. Pulsars—rapidly spinning neutron stars—serve as natural clocks, and their steady pulses allow scientists to detect minuscule changes caused by passing gravitational waves. This galactic-scale detector has provided an opportunity to map gravitational waves across the sky, revealing patterns and strengths that challenge previous assumptions. Lead author for one of the studies and a researcher at OzGrav and Monash University, Rowina Nathan comments “it is often assumed that the gravitational wave background will be uniformly distributed across the sky.” Miss Nathan explains “the galactic-sized telescope formed by the MeerKAT pulsar timing array has allowed us to map the structure of this signal with unprecedented precision, which may reveal insights about its source.”
Key findings:
Unprecedented gravitational wave signal
The study uncovered further evidence of gravitational wave signals originating from merging supermassive black holes, capturing a signal stronger than similar global experiments, and in just one-third of the time.
“What we’re seeing hints at a much more dynamic and active universe than we anticipated,” Dr Miles said. “We know supermassive black holes are out there merging, but now we’re starting to ask: where are they, and how many are out there?”
Detailed gravitational wave maps with unexpected hotspots
Using the pulsar timing array, the researchers constructed a highly detailed gravitational wave map, improving upon existing methods. This map revealed an intriguing anomaly – an unexpected hotspot in the signal that suggests a possible directional bias.
“The presence of a hotspot could suggest a distinct gravitational wave source, such as a pair of black holes billions of times the mass of our Sun,” said Miss Nathan. “Looking at the layout and patterns of gravitational waves shows us how our Universe exists today and contains signals from as far back as the Big Bang. There’s more work to do to determine the significance of the hotspot we found, but this an exciting step forward for our field.”
These findings open up exciting questions about the formation of massive black holes and the Universe’s early history. Further monitoring with the MeerKAT array will refine these gravitational wave maps, potentially uncovering new cosmic phenomena. The research also has broad implications, offering data that may aid international scientists in exploring the origins and evolution of supermassive black holes, the formation of galaxy structures, and even hints of early universe events.
With continued work using the MeerKAT array and plans to better understand the pulsar network and gravitational wave signal, researchers aim to refine the map of the gravitational wave background and verify the underlying cosmic structure. “In the future, we aim to understand the origin of the gravitational wave signal emerging from our data sets. By looking for variations in the gravitational waves across the sky, we’re hunting for the fingerprints of the underlying astrophysical processes”, adds Kathrin Grunthal, a researcher from the Max Planck Institute for Radio Astronomy and a co-author of one of the studies.
“By looking for variations in the gravitational wave signal across the sky, we’re hunting for the fingerprints of the astrophysical processes shaping our universe.”
Dr Matthew Miles and researcher Rowina Nathan are available for interviews. For enquiries, please contact ozgrav.comms@swin.edu.au
OzGrav is proud to celebrate Professor Matthew Bailes, Director of the ARC Centre of Excellence for Gravitational Wave Discovery, as a 2024 recipient of the prestigious Prime Minister’s Prize for Science. This recognition follows his recent Shaw Prize in Astronomy, cementing his standing as one of the world’s foremost astrophysicists.
Reflecting on the prize, Professor Bailes said, “It’s an amazing honour to receive the 2024 Prime Minister’s Prize for Science. If you told me as a child that one day I would receive a prize from the Prime Minister, I don’t think I would’ve believed you.”
Professor Bailes and his team first discovered fast radio bursts (FRBs) in 2007, significantly advancing scientific understanding of the universe. FRBs are intense bursts of radio waves that can last from less than a millisecond to a few seconds and are considered one of the great mysteries of the cosmos. “Professor Bailes’ work on fast radio bursts has created a vital new area of astrophysics that is unlocking the Universe’s mysteries in ways we could not have previously predicted,” said Professor Virginia Kilborn, Chief Scientist at Swinburne University of Technology.
Using archival data from Murriyang, CSIRO’s Parkes radio telescope on Wiradjuri Country, and the Molonglo radio telescope, Professor Bailes and his team discovered 27 of the first 30 FRBs. These discoveries now serve as a cornerstone for scientists studying some of the universe’s most powerful objects. Professor Brian Schmidt remarked, “Professor Bailes was instrumental in building special hardware for Murriyang, CSIRO’s Parkes radio telescope, enabling novel techniques to study short-duration pulsar pulses.” Professor Bailes now leads Australia’s research into FRBs, pulsars, and gravitational waves at OzGrav, testing gravity theories and advancing the scientific community’s understanding of the universe.
In addition to his groundbreaking research, Professor Bailes is a strong advocate for education and is dedicated to fostering the next generation of Australian scientists and engineers. “I get a lot of joy out of nurturing the next generation of scientists. I enjoy working with smart and passionate people,” he said, reflecting on his role as a mentor. “I love giving talks at schools and bringing students into the lab to see how scientists work.”
This year’s Prime Minister’s Prize for Science marks the 25th anniversary of Australia’s highest scientific honour, which celebrates groundbreaking achievements. Professor Bailes’ research exemplifies the global impact of Australian science and serves as an inspiration for future generations of scientists and innovators.
Watch the amazing video below where Matthew talks about the incredible discovery of Fast Radio Bursts! Hear the excitement behind the first detection and learn how these cosmic signals are reshaping our understanding of the universe.
We are delighted to celebrate two incredible OzGrav members who have been featured in the September issue of Nature Astronomy. OzGrav’s Creative Technologist and Scientific Visualisation Specialist, Carl Knox, created the captivating cover image depicting CSIRO’s ASKAP radio telescope alongside two versions of a mysterious celestial object: a neutron star or a white dwarf. The artwork brings to life the groundbreaking research led by OzGrav Associate Investigator, Dr. Manisha Caleb.
Dr. Caleb’s paper, published in Nature Astronomy in July, reveals the discovery of a slow-spinning neutron star that defies conventional astrophysics. Most neutron stars rotate in mere seconds, but this one takes nearly an hour—a finding that challenges our understanding of these dense celestial objects. Dr. Caleb explained, “It is highly unusual to discover a neutron star candidate emitting radio pulsations in this way. The fact that the signal is repeating at such a leisurely pace is extraordinary.”
Carl’s visualisation accompanies Dr. Caleb’s incredible research and perfectly captures the intrigue and mystery of this unusual celestial phenomenon. Their work together represents the power of combining science and art to deepen public understanding and appreciation of space discoveries.
Congratulations to both Manisha and Carl for their outstanding contributions to astronomy and for representing OzGrav on the international stage!
As part of National Science Week, the ARC Centre of Excellence (OzGrav) and the Centre for Astrophysics and Supercomputing (CAS) at Swinburne University proudly hosted “A Virtual Tour of Einstein’s Universe”, an inspiring public lecture presented by Professor Matthew Bailes, Director of OzGrav. Held on campus, the event attracted a strong turnout of science enthusiasts of all ages eager to learn about the universe’s greatest mysteries—from gravitational waves to black holes and pulsars.
Hosted by Professor Alan Duffy, the evening began with a warm introduction to Professor Bailes, followed by a fascinating journey through space and time. Professor Bailes explained how Einstein’s theories are shaping our understanding of the cosmos today. The audience was captivated by discussions on cutting-edge science, with a lively Q&A session rounding out the event.
The event also featured our National Science Week Ambassador, Dr Sara Webb, who helped create an engaging and educational experience, fostering an exciting atmosphere for learning and exploration during National Science Week.
In addition to the public lecture, OzGrav’s Outreach Ambassadors hosted interactive workshops, providing hands-on activities for attendees of all ages and fostering an exciting atmosphere for learning and exploration.
This successful event wouldn’t have been possible without the dedication of the OzGrav team and the Swinburne outreach staff. Stay tuned for more exciting events from OzGrav and Swinburne!
For those who missed the event, a recording of the lecture is below and you can also explore the gallery to view photos from the event.
We are delighted to share that the Einstein-First project, a groundbreaking science education initiative, has been awarded the Science Engagement Initiative of the Year at the 2024 WA Premier’s Science Awards. This recognition highlights the exceptional impact Einstein-First has made in transforming the way young students, especially girls, engage with and understand modern science.
Einstein-First began as an outreach effort at the Gravity Discovery Centre and has since evolved into a national program that brings Einstein’s 21st-century science to students aged 7 to 15. The program’s innovative approach disrupts traditional teaching paradigms by using toys, songs, and hands-on activities to make complex scientific concepts accessible and engaging.
The program’s success is evident in its rapid expansion. Launched nationally by Prof. David Blair, Prof. Ju Li, Prof. Susan Scott and Prof. Marjan Zadnik, along with others, Einstein-First has already trained 150 teachers across 55 schools, impacting over 10,000 students, including 3,000 First Nations students in Queensland. The train-the-trainer model has been particularly effective, empowering teachers to bring Einstein’s science into classrooms across the country.
OzGrav has been a proud supporter and collaborator of Einstein-First. This partnership is a testament to our shared commitment to advancing public understanding of modern physics and inspiring the next generation of scientists.
We congratulate the entire Einstein-First team for their outstanding achievement and well-deserved recognition and look forward to continuing our collaboration to further science education and engagement across Australia.
About the Western Australia Premier’s Science Awards
Now in its 23rd year, the Western Australia Premier’s Science Awards celebrate the outstanding scientific research and engagement efforts in the region. The Science Engagement Initiative of the Year category specifically recognises initiatives that have made a significant contribution to raising community awareness, interest, and participation in science.
Neutron stars are extremely dense objects, second only to black holes. A teaspoon of neutron star matter weighs as much as Mt. Everest. Under such high densities, neutron stars possess exotic physics that cannot be reproduced on Earth.
We have been studying a subgroup of neutron stars, namely pulsars, that release their energies mainly through electromagnetic radiation. But these stars are only a fraction of the total neutron star population in the Milky Way Galaxy. We are missing out on other types of neutron stars that may not produce much electromagnetic radiation.
As a neutron star rotates, any mountains on its surface – even if they are just a few millimetres tall – will create ripples in the four-dimensional fabric of space- time. Such ripples are known as continuous gravitational waves, or continuous waves for short. Compared to the gravitational waves that have been detected, continuous waves are fainter but constant – similar to the humming of a fridge, as opposed to a loud bang.
Observing neutron stars through continuous waves provides us with information that is complementary to what can be learnt from pulsars, so that we can paint a more complete picture of the unknown physics that lies within. However, continuous waves from neutron stars are still undetected. To know whether they are detectable, and what we can learn from them, we need to perform simulations to see if our current and future gravitational wave detectors can detect continuous waves.
In this study, we looked at the capabilities of two detectors: LIGO, the first to detect gravitational waves in 2015; and the Einstein Telescope, a next- generation detector that is expected to be constructed in the 2030s. The first step to detecting continuous waves is to make sure that we are looking at the right place. The current catalogue of neutron stars contains only pulsars that may not emit any continuous waves. To get a full picture of the neutron star population in the Galaxy, we also need neutron stars that emit continuous waves. We simulated the entire neutron star population in the Galaxy, which includes continuous wave-emitting neutron stars. These stars have different energies and release different amounts of electromagnetic and continuous waves.
From this population of neutron stars, we then estimated the continuous waves produced by these stars, and how the two detectors respond to them. Using a technique called Bayesian inference, we performed searches on the faint “hums” amidst all the additional noise from the detectors. Being a next- generation detector, the Einstein Telescope is larger and more sensitive than LIGO, so the weak continuous wave signals can be more easily identified – just like how you can hear fainter sounds when you are in a quieter room.
The factor that determines the amount of continuous waves generated, known as the ellipticity, could be measured by the Einstein Telescope with an error of between 5 and 50% with 5 years of observation. This property of the neutron star cannot be determined by other methods. The limiting factor, we found, is the preciseness of our measurement of a quantity called the braking index. This number determines the fraction of a neutron star’s energy that is released as continuous waves. The ability to measure this number directly affects our measurement of ellipticity.
Our study demonstrated that future detectors, such as the Einstein Telescope, can detect continuous waves. Neutron star properties such as ellipticity, which previously could not be determined, can then be measured through the detected continuous waves. Our work provides a new way to probe the physics of neutron stars, and additional motivation to construct the next generation of gravitational wave detectors.
Reference: “Population Synthesis and Parameter Estimation of Neutron Stars with Continuous Gravitational Waves and Third-Generation Detectors”
Yuhan Hua, Karl Wette, Susan M. Scott, Matthew D. Pitkin.
Artist’s impression showing a companion white-dwarf star orbiting a pulsar. The dense companion warps the fabric of spacetime, compressing it, and delaying the pulses coming from the pulsar. Credit: Carl Knox / OzGrav
A neutron star close to Earth is spinning as fast as a blender. Known as a millisecond pulsar, it is rotating at 174 times per second but much of its characteristics have remained a mystery. Now, thanks to almost 30 years of observations from Murriyang, CSIRO’s Parkes radio telescope, we know its mass. And that’s the key to knowing so much more.
In a series of three papers accepted for publication in Astrophysical Journal Letters, a global group of scientists describe how Murriyang together with NICER (Neutron Star Interior Composition ExploreR), NASA’s X-ray telescope on the International Space Station, have accurately measured the mass and radius of this nearby neutron star.
According to the Australian lead researcher on the project Dr Daniel Reardon, from the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) and Swinburne University of Technology, a neutron star is made of extreme matter on the brink of becoming a black hole.
“Being able to measure its mass and radius tells us how squeezable neutron stars are and how matter behaves inside their dense core, which is denser than the nucleus of an atom,” he said.
Particle accelerators, such as the Large Hadron Collider, are also used to study matter at its extremes, but these experiments fail to predict the behaviour of the unique matter in the cores of neutron stars. This means neutron stars are some of the best laboratories for physics. Measuring their masses and sizes is a way to get new insights into fundamental nuclear physics.
NICER is on a mission to study neutron star interiors by detecting and mapping X-ray emission from million-degree hot spots on the surface of the star. Dr Reardon, the OzGrav team, and other researchers using radio data from Murriyang, owned and operated by CSIRO, Australia’s national science agency, provided the mass of the pulsar, a key part of the NICER mission to measure the radius.
Dr Reardon has been observing this neutron star since he was a student ten years ago.
“There were researchers studying the same pulsar with Murriyang for twenty years before me. It’s important that we have long-term data on the star to get accurate information,” he said.
This is part of the Parkes Pulsar Timing Array (PPTA) collaboration to monitor a set of pulsars over long timescales.
Dr Andrew Zic (CSIRO), Primary Investigator of the PPTA project, says the collaboration’s precise measurements of pulsars with Murriyang has produced highly valuable datasets for many projects.
“This has been made possible by regular upgrades to Murriyang, which has meant that our PPTA data have consistently been of world-leading quality, as seen in this work,” Dr Zic said.
By compiling and analysing this large data set, researchers are getting closer to detecting gravitational waves with pulsars. Dr Reardon and the team used this data to support the NICER mission in a novel way.
“At CSIRO’s Parkes Observatory we have been tracking – for decades – tiny (microsecond) delays in the arrival times of pulses sent out the neutron star, caused by space compressing due to the mass of its white-dwarf companion star,” Dr Reardon said.
Space is stretched and squashed by the mass of objects, which is described in Einstein’s theory of gravity. The microsecond delays are predicted by the theory and the detailed information collected over many years allowed the team to accurately calculate the mass of both the dwarf star and the pulsar.
With the mass confirmed, the NICER team could then calculate the radius of the pulsar from their data. This helps build a picture of the matter making up a neutron star.
Understanding the matter will allow scientists to better predict the gravitational wave signatures created when neutron stars collide and collapse into black holes. Neutron star collisions release a burst of gravitational waves in an enormous explosion called a kilonova, which can be seen by many telescopes, including Xray telescopes and radio ones.
According to OzGrav’s Dr Anais Möller from Swinburne University of Technology, an expert in searching for these collisions, measuring the mass and radius of pulsars tells us how neutron stars might get ripped apart and what we can expect to see in the resulting kilonova.
Dr Reardon says because this pulsar has a mass similar to a typical neutron star, measuring its mass and radius is crucial for understanding the behaviour of matter at extreme densities.
“This research advances our fundamental understanding of how the Universe operates.”
Australian scientists from the University of Sydney and Australia’s national science agency, CSIRO, have detected what is likely a neutron star spinning slower than any other ever measured.
No other radio-emitting neutron star, out of the more than 3000 discovered so far, has been discovered rotating so slowly. The results are published today in Nature Astronomy.
Lead author Dr Manisha Caleb from the University of Sydney Institute for Astronomy said: “It is highly unusual to discover a neutron star candidate emitting radio pulsations in this way. The fact that the signal is repeating at such a leisurely pace is extraordinary.”
This unusual neutron star is emitting radio light at a rate that is too slow to fit with current descriptions of radio neutron star behaviour. This provides new insights into the complex life cycles of stellar objects.
Matter is so dense that negatively charged electrons are crushed into positively charged protons and what’s left is an object made up of trillions of neutrally charged particles. A neutron star is born.
Given the extreme physics with which these stars collapse, neutron stars typically rotate mind-bendingly fast, taking just seconds or even fractions of a second to fully spin on their axis.
Now, astronomers at the University of Sydney and CSIRO have discovered a compact object repeating its signal with a comparatively leisurely period just shy of one hour.
The discovery was made using CSIRO’s ASKAP radio telescope on Wajarri Yamaji Country in Western Australia.
The ASKAP radio telescope can see a large part of the sky at once, which means it can capture things researchers aren’t even looking for. CSIRO scientist Dr Emil Lenc, co-lead author on the paper, said they wouldn’t have found this strange object if it wasn’t for ASKAP’s unique design.
“We were simultaneously monitoring a source of gamma rays and seeking a fast radio burst when I spotted this object slowly flashing in the data. Three very different things in one field-of-view,” he said.
“ASKAP is one of the best telescopes in the world for this sort of research, as it is constantly scanning so much of the sky, allowing us to detect any anomalies.”
The origin of such a long period signal remains a profound mystery, although two types of stars are prime suspects – white dwarfs and neutron stars.
“What is intriguing is how this object displays three distinct emission states, each with properties entirely dissimilar from the others. The MeerKAT radio telescope in South Africa played a crucial role in distinguishing between these states. If the signals didn’t arise from the same point in the sky, we would not have believed it to be the same object producing these different signals,” Dr Caleb said.
While an isolated white dwarf with an extraordinarily strong magnetic field could produce the observed signal, it is surprising that nearby highly-magnetic isolated white dwarfs have never been discovered. Conversely, a neutron star with extreme magnetic fields can quite elegantly explain the observed emissions.
While a slow-spinning neutron star is the likely explanation, researchers said they cannot rule out that the object is part of a binary system with a neutron star or another white dwarf.
More research will be required to confirm whether the object is a neutron star or white dwarf. Either way, it will provide valuable insights into the physics of these extreme objects.
“It might even prompt us to reconsider our decades-old understanding of neutron stars or white dwarfs; how they emit radio waves and what their populations are like in our Milky Way galaxy,” Dr Caleb said.
Professor Tara Murphy, leading radio astronomer and head of the School of Physics at the University of Sydney, said: “Until the advent of our new telescopes, the dynamic radio sky has been relatively unexplored. Now we’re able to look deeply, and often, we are seeing all kinds of unusual phenomena. These events give us insights into how physics works in extreme environments.”
