An international group of scientists, including dozens of Australians, this weekend announced the detection of the most massive binary black hole merger yet witnessed in the universe. The black hole that resulted from this cataclysmic event is more than 80 times as massive as our Sun.
The discovery of GW170729 – along with evidence of nine other black hole mergers – comes just over one year since scientists announced they had witnessed, for the first time, the violent death spiral of two dense neutron stars via gravitational waves, another set of major astrophysical discoveries have been announced in the US. The series of papers including the work of the Australians, all from the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), present the full catalogue of observations of binary black hole and binary neutron star mergers from the first two observing runs (2015, 2016-17) of the Advanced LIGO (US) and Advanced Virgo (Italy) gravitational-wave detectors. According to Dr Meg Millhouse, from OzGrav and the University of Melbourne, the papers outline a catalogue of all gravitational wave signals "heard" by the Advanced LIGO detectors in the last three years. “These signals are generated by some of the most violent events in the universe, when pairs of neutron stars and black holes – each with many times more mass than our sun – come crashing together,” she said. Dr Simon Stevenson, from OzGrav and Swinburne University, said that the additional information of the other nine binary black holes, “means we are learning things about the population, such as how frequently binary black holes merge in the universe (once every few hundred seconds somewhere in the universe) and whether small (low mass) or large (high mass) black holes are more common -- there are many more light black holes (around 5-10 times the mass of the sun) in the universe than heavy black holes (around 30-40 times the mass of the sun), but the heavy ones are ‘louder’ in gravitational-waves, and easier to ‘hear’ colliding,” he said. “With each new detection we learn something more about how these extraordinary objects came to be. The detections also help to answer questions about the theory of gravity, the formation of galaxies, and how heavy elements (including gold and platinum) are produced”, said co-author Dr Xu (Sundae) Chen from OzGrav and the University of Western Australia. Another author, student Colm Talbot from OzGrav and Monash University, in a separate paper describes how the detection of these new black holes will assist in understanding the Universe’s entire population of black holes. “Each of these black holes formed from huge stars which died in violent explosions called supernovae. By studying these black holes, we act as black hole archaeologists to learn how these cosmic giants die,” he said. Last year Dr Paul Altin from OzGrav and the Australian National University was part of LIGO's "rapid response team", whose job it is to be ready to receive a detection alert at any time, day or night, in order to quickly analyse the data and decide whether the event is significant enough for an alert to be sent to our partner astronomers for follow-up observations. According to Dr Altin, in 2019 Advanced LIGO comes back online with even higher sensitivity, in part due to the use of quantum squeezing. “Squeezing allows us to get around noise that comes from quantum mechanics, the fundamental theory that governs microscopic particles,” he said. The Advanced LIGO squeezer was designed at ANU and is currently being installed in the US. Several OzGrav members are currently in the US at LIGO Hanford installing upgrades to the detector. According to Dr Dan Brown, from OzGrav and the University of Adelaide, the next observation run aims to use squeezed light to reach the target sensitivity to look for extreme events. “With OzGrav's expertise in squeezed light and adaptive optics for compensating thermal effects from the increased laser power we're making significant contributions towards improving LIGO for the next run,” he said. The ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) is funded by the Australian Government through the Australian Research Council Centres of Excellence funding scheme. OzGrav is a partnership between Swinburne University of Technology (host of OzGrav headquarters), the Australian National University, Monash University, University of Adelaide, University of Melbourne, and University of Western Australia, along with other collaborating organisations in Australia and overseas. LIGO is funded by the NSF, and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects. Financial support for the Advanced LIGO project was led by the NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council) making significant commitments and contributions to the project. More than 1,200 scientists and some 100 institutions from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration and the Australian collaboration OzGrav. Additional partners are listed at http://ligo.org/partners.php. The Virgo collaboration consists of more than 280 physicists and engineers belonging to 20 different European research groups: six from Centre National de la Recherche Scientifique (CNRS) in France; eight from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; two in the Netherlands with Nikhef; the MTA Wigner RCP in Hungary; the POLGRAW group in Poland; Spain with the University of Valencia; and the European Gravitational Observatory, EGO, the laboratory hosting the Virgo detector near Pisa in Italy, funded by CNRS, INFN, and Nikhef
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Dr Aidan Brooks (LIGO Laboratory Caltech) visited Australia in Aug-27 through Sep-21 2018 to visit the University of Adelaide (UoA) with additional short trips to UWA, ANU and Monash. The focus of the trip was divided into three main research areas with different time horizons:
Advanced LIGO support Extensive discussions were held with Dan and Peter on how Adelaide can continue to support the Hartmann sensor (HWS) code for LIGO. I also discussed the cavity eigenmode modulation (CEM) technique for cavity mode-matching and alignment that Alexei has developed. A+ preparation A+ is a medium-scale upgrade to Advanced LIGO (aLIGO) that will introduce frequency dependent squeezing and new coatings to the aLIGO test masses. Much of the trip was focused on development of adaptive optics, designed at Adelaide, for use in A+. Successful deployment of these optics will significantly reduce the complexity of the A+ adaptive optics system and could potentially reduce the budget for this system by $200k or more. LIGO-Voyager The third generation of LIGO will be called LIGO-Voyager and will require, amongst other large-scale upgrades, a 2-micron laser source so Seb showed me the one that UoA are developing. Work at other OzGrav Nodes At UWA, I had long discussions with Zhao and gave some input on their plans to develop technologies for Voyager. The Gingin facility is potentially the only site in the next few years to have a suspended Fabry-Perot cavity with silicon optics and two micron lasers and thus could be valuable for testing. I spent two days at ANU (overlapping with Rana Adhikari during that time). We provided input on the OzGrav proposal to build a high-frequency GW detector in Australia, and Bram and I discussed the requirements for two-stage tip-tilt. Postdoctoral research position at Monash University.
Theoretical Astrophysics for 3 years full-time. Applications close 30 November 2018 to start in September 2019 (the start date is flexible). I welcome applications from candidates with broad interests connected to any of the following areas of theoretical astrophysics: *Gravitational-wave astrophysics and the astrophysical interpretation of exciting new data on binary neutron star and black hole mergers * Modelling massive stellar and binary evolution * The interpretation of high-energy astrophysical transients, including tidal disruption events and gamma ray bursts * Stellar dynamics * Astrostatistics http://careers.pageuppeople.com/513/cw/en/job/582537/research-fellow-theoretical-astrophysics Enquiries: Professor Ilya Mandel, [email protected] Researchers are applying big data analysis techniques used in astronomy to better understand diseases of the eye and brain.
The team, led by ophthalmologist Dr Peter van Wijngaarden (CERA) and astrophysicist Associate Professor Christopher Fluke (Centre for Astrophysics and Supercomputing at Swinburne University and OzGrav), will be working together to apply the same big data analysis used by astronomers in their study of the universe, to the field of ophthalmology. The collaboration will be formalised thanks to a generous donation from Australian entrepreneur Dr Steven Frisken, CEO of ophthalmic tech company Cylite, who was one of four people jointly awarded the Prime Minister’s Prize for Innovation last night in Canberra. https://www.cera.org.au/2018/10/eyes-on-the-sky/ Daniel Brown from OzGrav’s team at the University of Adelaide travelled to MIT for the A+ Balanced Homodyne Workshop, 11-12 Oct, 2018. Overall this was a productive meeting which favourably demonstrated how the research being undertaken here in the Adelaide node of OzGrav is pushing the future detectors forward.
Recently the next iteration of the LIGO experiment was announced, named A+. This upgrade takes us from Advanced LIGO and further improves the sensitivity. One of the more involved upgrades is to change the gravitational wave readout scheme, from what is currently used and is called “DC Readout” to “Balanced Homodyne Readout” (BHD). Both of these techniques are employed to provide a strong optical field, called a local oscillator, at the output port, which beats with the optical fields generated by a gravitational wave and allows us to measure them on a photodiode. For A+ the plan is pick off a small amount of light from the power recycling cavity through one of its mirrors. We then have to shape and align this light correctly and combine it with the signal coming out of the detector. This beam shaping and designing of optical control systems is some of the core OzGrav research Daniel is undertaking at the University of Adelaide. The outcome of this meeting was that much work still needs to be done. The output part of LIGO is having a complete redesign. New suspension stages must be designed to accommodate the adaptive optic elements being developed at Adelaide. There is also scope for our new beam shape sensing technique to also be employed for controlling these adaptive elements. Next a control system must be designed and modelled for all this, which is being simulated in my modelling software Finesse. In the coming months we aim to write several design documents outlining all the new elements for the BHD system of A+. - Daniel Brown, Postdoctoral Researcher at University of Adelaide From March to June 2018 Sebastian (postdoc), Alexei (PhD student), and Daniel (postdoc) from the OzGrav team at the University of Adelaide travelled to the USA to attend the LIGO-Virgo Collaboration (LVC) meeting along with further trips to LIGO Hanford and the California Institute of Technology (Caltech). One of Daniel’s main research topics is the creation of numerical simulation software, called Finesse, which is used for understanding the complex optical interferometers that are at the core of gravitational wave detectors; we use this for design and commissioning work. Sebastian's main research focus is 2µm fiber laser development which is one of the core research topics for OzGrav instrumentation. His research is in the development of lasers for the third generation of gravitational wave detectors. Sebastian spent time during the LVC engaging with research groups focussed on the current and future laser systems. Following the LVC he travelled south to Pasadena to visit the Caltech arm of LIGO Lab. This gave him an opportunity to examine the material and detector technologies being developed for the future detectors. While there he helped design the optical layout for the signal recycling heater and characterise the CO2 laser. After this Sebastian joined Alexei and Daniel in Hanford and participated in the mode matching of the 70W upgrade to the prestabilised laser and helped with the implementation of the CO2 laser heater. Arriving at the LIGO site at first is nothing short of daunting. Usually we work on small table-top optics experiments. The physical size of the LIGO experiment always blows me away, from the size of the vacuum chambers to the arms that shoot out into the desert. The team at LIGO was amazing; their patience in teaching us how it all works and trust in us to let us work on the experiment really made the trip. During our time there we all worked on several parts. First, we helped design and construct the new prototype adaptive optic system. This system uses a CO2 laser to heat the signal recycling mirror to induce a small lens on its surface. This then shapes the beam exiting the interferometer and will be used to better shape it for extracting the signal. This involved a lot of plumbing work (getting covered in aged coolant left in old pipes...) and aligning the CO2 laser into the vacuum chamber to correctly deform the mirror. Alexei also looked into how we can better interpret cavity mode scans to infer the correct way to shape the laser beam. From this we found that we can actually extract more information than we expected previously, such as the astigmatism of the beam. Using this knowledge he wrote a new commissioning tool for analysing the output mode cleaner scans in a more automated and easier to use fashion.
We also helped in mode matching the squeezer beam to the interferometer and develop better Finesse models of the output path. Before we left we then also helped test the new Hartmann sensor system for sensing the deformations in the end test mass mirrors, something that previously had not worked optimally. PhD scholarship at ANU!
See your future career in Gravitational Physics. Apply for admission at ANU by 31 October. www.anu.edu.au/students/scholarships-fees/scholarships/anu-phd-scholarships physics.anu.edu.au/quantum/cgp/ Enquiries: [email protected] The neutron star merger, known as GW170817, occurred 130 million light-years from Earth and sent a burst of both gravitational and electromagnetic waves rippling through space that reached the Earth one year ago.
In the aftermath of the violent collision, GW170817 was observed worldwide by telescopes across the electromagnetic spectrum. By tracking changes in the optical, radio, and X-ray emission of the afterglow, scientists including Swinburne's Dr Adam Deller, from OzGrav, were able to study how the material flung out during the merger interacted with its surroundings. Read more here. OzGrav is delighted to be involved in a new art-science planetarium show that will have its world premier at the Melbourne International Arts Festival from October 6-13, 2018.
Particle/Wave sees poets, musicians, sound and video artists joining forces with renowned scientists to interpret the theories of gravitational waves, which Stephen Hawking has called “a completely new way of looking at the universe.” Particle/Wave is directed by Alicia Sometimes, and includes narration by OzGravers Kendall Ackley, Lilli Sun, and Alan Duffy, along with video contributions from our own Mark Myers and Carl Knox. OzGrav Associate Investigator Dr Adam Deller has helped test Einstein’s theory of general relativity and shown it still can’t be proven wrong, using the complicated orbital dance of three compact stars. Einstein’s strong equivalence principle says all objects should fall the same way in a gravitational field, regardless of their composition or how dense they are.
After five years of intensive observation of a triple stellar system, the international team of nine astronomers was able to conclude that the theory of general relativity is still relevant, as seen in the research paper published in the prestigious international science journal, Nature. “This particular system consists of one ultra-dense neutron star and two less-dense white dwarf stars, which makes these stars the dream team for testing relativity,” Dr Deller says. Read the press release here. A new technique developed to detect the faint background hum of gravitational waves in the Universe is making headlines! Eric Thrane and Rory Smith from OzGrav's Monash Node have made the remarkable prediction that their new technique - combined with the grunt of a supercomputer like Swinburne's OzSTAR - could give them the exquisite level of sensitivity needed to measure the subtle background noise caused by black holes and neutron stars colliding throughout the universe.
Their result is described in The Age and ABC news, and on TV on the 7:30 Report. On 16 March 2018, OzGrav Deputy Director Prof David McClelland (ANU) received the International Organisation for Quantum Communication, Measurement and Computing Award for Outstanding Achievements in Quantum Experimentation. In bestowing McClelland with this award, the organisation cited his “pioneering experimental work and leadership in the development of squeezed vacuum light sources in the audio-band and its successful application to the gravitational wave detector interferometers GEO and LIGO.” The award was shared in equal parts with OzGrav Partner Investigator Prof Nergis Mavalvala (MIT) and Prof Roman Schnabel (Hamburg).
Advances in this technology are sure to lead to even more discoveries. Says Prof McClelland, "manipulating the quantum world to enhance the sensitivity of world’s biggest laser interferometers will enable the deepest searches yet for new gravitational wave sources". “It is gratifying to see Professor McClelland's pioneering work in quantum squeezing acknowledged with this prize. His group's work will enable us all to see further into the Universe and accelerate the advancement of the new field of gravitational wave astrophysics", says OzGrav Director Prof Matthew Bailes. Image: Prof McClelland receiving his award from Prof Joerg Schmiedmayer, Chair of the International Organisation for Quantum Communication, Measurement and Computation. OzGrav Deputy Director David McClelland was awarded the Walter Boas Medal by the Australian Institute of Physics for his contributions to “one of the greatest achievements in the history of physics”, the direct observation of gravitational waves. "For his role in bringing about the epochal breakthrough, and securing Australia’s place in the international collaboration that made it possible, Professor David McClelland of the Australian National University has been awarded the 2017 Walter Boas Medal by the Australian Institute of Physics."
In addition to his role in OzGrav, he is Professor of Physics, Department of Quantum Science and Director of the ANU Centre for Gravitational Physics. He is also the Chief Investigator for Australia's Partnership in Advanced LIGO. The Walter Boas Medal is awarded yearly by the AIP for excellence in research. A Swinburne astronomer is part of an international discovery effort bringing scientists one step closer to understanding the physics of binary neutron star mergers and the universe at large. The discovery, made by an international team of astronomers, suggests that a narrow and super-fast 'jet' of material blasted out during the cataclysmic neutron star merger, slammed into the environment surrounding the merging neutron stars and inflated a bubble-like cocoon. The findings, published in Nature, contradict a popular theory describing the aftermath of the recently observed neutron star merger — namely, that the beam-like jet thought to be associated with highly energetic phenomena called gamma-ray bursts had been seen directly, immediately after the merger. “The burst of gamma-rays from this merger didn't come directly from a tightly focused, high-speed jet that just grazed our line of sight; instead, we attribute them to a more slowly moving outflow of material that had absorbed some of the jet’s energy,” says Swinburne astronomer Dr Adam Deller, ARC Future Fellow at the Centre for Astrophysics and Supercomputing and Associate Investigator at the ARC Centre of Excellence for Gravitational Wave Discovery. “We confirmed this by studying the radio emission produced by this outflowing material weeks and months after the merger.” Dr Deller believes this finding will impact astronomy in two important ways. “The 'canonical' model of what happens when neutron stars merge will be revised and improved,” he says. “And when LIGO detects more binary neutron star mergers in the future, we now expect to see an 'afterglow' counterpart more frequently than previously expected, which will help us pin down their locations and is good news for learning more about the extreme physics of these merger events.” Australia and the world looking to the skies The findings were made possible by the cooperative efforts of a team of astronomers and facilities world-wide, and Dr Deller stresses the importance of having radio telescopes in Australia and the world monitoring these events. "As we've kept our radio telescopes trained on the site of this event, we've continued to learn more and more about the nature of the explosion that accompanied the neutron star merger,” he says. "Having a suite of radio telescopes world-wide, including in Australia, has underpinned this monitoring effort. By observing at a range of times and radio frequencies, we've learnt much more about the explosion than any one facility could have provided alone." Dr Tara Murphy, an ARC fellow at University of Sydney who led observations with the Australia Telescope Compact Array, says that detecting and monitoring radio waves is critical to understand what happens when two neutron stars merge. “We now know that what we’re observing is not what we expected - we haven’t seen anything quite like it before.” “Australian facilities have played a vital role in monitoring radio waves from the merger. We’re able to detect this high energy event, 130 million light years away, tracking it as the explosion evolves with time.” Looking to the future The research team say that future observations with international telescopes LIGO, Virgo, and others will help further clarify the origins and mechanisms of these extreme events. The observatories should be able to detect additional neutron-star mergers—and perhaps eventually, mergers of neutron stars and black holes. The findings were made with the Karl G. Janksy Very Large Array in New Mexico, the CSIRO Australia Telescope Compact Array, and the Giant Meter-wave Radio Telescope in India. The lead author is Kunal Mooley, formerly of the University of Oxford and now a Jansky Fellow at Caltech. To view the complete findings, see: A mildly relativistic wide-angle outflow in the neutron star merger GW170817 Image credit: NRAO/AUI/NSF: D. Berry.
The image shows a radio telescope (upper right) observing GW170817 (lower left). The jet within GW170817 (narrow bright beam emanating from GW170817) has dissipated its energy into the dynamical ejecta (shown in brown/yellow) and thus given rise to a wide-angle outflow (shown in red/pink) - a scenario called the choked-jet cocoon. LIGO and Virgo announce the detection of a binary merger from two "lightweight" black holes17/11/2017 Scientists searching for gravitational waves have confirmed yet another detection from their fruitful observing run earlier this year. Dubbed GW170608, the latest discovery was produced by the merger of two relatively light black holes, 7 and 12 times the mass of the sun, at a distance of about a billion light-years from Earth. The merger left behind a final black hole 18 times the mass of the sun, meaning that energy equivalent to about 1 solar mass was emitted as gravitational waves during the collision.
GW170608 is the lightest black hole binary that LIGO and Virgo have observed – and so is one of the first cases where black holes detected through gravitational waves have masses similar to black holes detected indirectly via electromagnetic radiation, such as X-rays. Prof Matthew Bailes delivers a history of gravitational waves in virtual and augmented reality to a packed theatre at Swinburne University of Technology. We were delighted to have Prof Brian Schmidt as our MC, and a personal message from Prof Barry Barish to launch our Centre of Excellence for Gravitational Wave Discovery (OzGrav). Read our media announcement here, or watch the OzGrav Director Professor Matthew Bailes explain the discovery: MEDIA ADVISORY: Australian scientists to discuss new developments in gravitational-wave astronomy NEWS BRIEFING: Tue 17 Oct 2017 at 09:00 AEDT at Old Parliament House, Canberra and online Scientists from OzGrav (The ARC Centre of Excellence for Gravitational Wave Discovery), CAASTRO (The ARC Centre of Excellence for All-sky Astrophysics) and the LIGO-Virgo Collaboration will reveal new details and discoveries made in the ongoing search for gravitational waves. Join us for this media briefing, moderated by Australia's Chief Scientist Dr Alan Finkel, when Australian experts will discuss the research and its implications. The Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav) is delighted to congratulate the winners of this year’s Nobel prize in Physics for the leadership roles they played in the discovery of gravitational waves by the Advanced LIGO detector.
The three winners are Rainer Weiss, from the Massachusetts Institute of Technology, Kip Thorne and Barry Barish, both of whom are from the California Institute of Technology. OzGrav is very fortunate to have Barry Barish serve on our Scientific Advisory Committee. Australia’s Minister for Education and Training, Simon Birmingham, also congratulated the 2017 Nobel Prize winners. “OzGrav is helping Australia stay at the cutting edge of this new and rapidly advancing field,” said Senator Birmingham. “It will capitalise on the first detections of gravitational waves, to understand the extreme physics of black holes and warped space-time.” The LIGO Scientific Collaboration and the Virgo collaboration report the first joint detection of gravitational waves with both the LIGO and Virgo detectors. This is the fourth announced detection of a binary black hole system and the first significant gravitational-wave signal recorded by the Virgo detector, and highlights the scientific potential of a three-detector network of gravitational-wave detectors.
The three-detector observation was made on August 14, 2017 at 10:30:43 UTC. The two Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, and funded by the National Science Foundation (NSF), and the Virgo detector, located near Pisa, Italy, detected a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes. A paper about the event, known as GW170814, has been accepted for publication in the journal Physical Review Letters. OzGrav headquarters is pleased to call for applications for the following two travel funding programs.
Applications for both programs closed Friday 22nd September 2017. International Visitor Funding Program The OzGrav International Visitor Program has been established to support travel by leading international scientists to collaborate on OzGrav projects with OzGrav CIs and other members within Australia. This is a competitive funding program, with potential visitors to be nominated by OzGrav CIs. Visitors will be encouraged to visit multiple nodes, participate in node and theme meetings, and give seminars or public talks during their visit. At least one third of the budget should come from the hosting or sponsoring node(s). Further details, guidelines, and application instructions are contained in the international visitor funding application form. Student/Postdoc Travel or Placement Awards We are inviting applications from OzGrav students and postdocs for travel awards to enable them to spend time working at other nodes or collaborating organizations on OzGrav projects, and/or to attend national or international conferences to communicate OzGrav research. This is a competitive funding program. Successful applicants may be awarded up to $3,000 for international placements/travel or up to $2,000 for domestic placements/travel. At least one third of the budget should come from the applicant’s home or host institution. Further details, guidelines, and application instructions are contained in the student/postdoc travel award application form. The Laser Interferometer Gravitational-wave Observatory (LIGO) has made a third detection of gravitational waves, ripples in space and time, demonstrating that a new window in astronomy has been firmly opened.
As was the case with the first two detections, the waves were generated when two black holes merged to form a larger black hole. In the latest merger, the final black hole was some 50 times the mass of our Sun. The recent detection, called GW170104, is the farthest yet, with the black holes located about three billion light-years away. Einstein's theory of general relativity predicts that colliding black holes and neutron stars generate ‘gravitational waves’ that cause ripples in the fabric of space-time. After such an event, space-time does not return to its original state, instead it stays permanently warped. The astonishing prediction of Monash University researchers (and OzGrav investigators) Eric Thrane and Paul Lasky, along with student Lucy McNeill is that this warping could be detected using the advanced LIGO detector - even when the signal that caused the warping was not observed.
More details in the Press Release, New Scientist article, and the full publication. OzGrav researcher David Blair (UWA) writes in The Conversation about a paper in Nature magazine co-authored by fellow OzGrav researcher Chunnong Zhao (UWA). Zhao and colleagues have created an exciting new design that makes use of quantum entanglement to make more sensitive gravitational wave detectors.
Congratulations to OzGrav Program Leader Prof Susan Scott (ANU) who was selected to participate in the Homeward Board program, a groundbreaking leadership, strategic and science initiative for women, set against the backdrop of Antarctica. The initiative, turned global movement, aims to heighten the influence and impact of women with a science background in order to influence policy and decision making as it shapes our planet, within 10 years.
Prof Scott will undertake a year-long program to develop leadership and strategic capabilities, including an Antarctic expedition in February 2018. We will be following her journey over the next year here at ozgrav.org! Listen to Susan Scott speak about the program and how she is preparing for the journey with this 2CC radio podcast. |
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