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+ 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.
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
Enquiries: Professor Ilya Mandel, Ilya.Mandel@monash.edu
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.
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.
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.