PhD Projects with Gravitational Wave Group
School of Physics, University of Western Australia
Gravitational waves are ripples of space and time created by violent
events in the Universe such as mergers of two black holes or corecollapse of massive stars at supernovae. Their existence was first
predicted by Einstein's general theory of relativity. Gravitational waves
will represent a completely new spectrum in astronomy and its detection
will revolutionize our understanding of how space and time behave in
violent events. The ultimate direct detections of gravitational waves are
confidently expected in the coming decade, as the advanced
gravitational wave detectors start to operate.
The advanced gravitational wave detectors are
giant interferometers looking for those tiny ripples
in spacetime induced by astronomical events.
There are worldwide efforts to create the
gravitational wave detector network and develop
cutting edge techniques for improving the
sensitivities of the advanced gravitational wave
detectors. Figure 2 shows the gravitational wave
detector network including the 3 existing km scale
detectors LIGO (4km US), and Virgo (3km, an
Italy-Franc collaboration, located near Pisa, Italy),
the 3 km detector under construction KAGRA
(Japan), the 600m detector GEO600 (a GermanUK collaboration, located at Hanover, Germany),
as well as the Australian 80m test facility.
Figure 2. Global network of gravitational wave
detectors
Australia plays an active role in developing technologies for the advanced gravitational wave
detectors. The University of Western Australia group is part of the Australian Consortium of
Interferometric Gravitational wave Astronomy (ACIGA), and operates ACIGA High Optical Power
facility. We work on developing techniques to further improve the sensitivity of the advanced
detectors below the standard quantum limit (SQL), which is currently the limiting sensitivity. The
development of advanced techniques to improve the sensitivity of gravitational wave detectors leads
to exciting new physics phenomena and techniques that may have application beyond gravitational
wave detectors. Our project covers a range of projects from gravitational wave data analysis, and
optical cavity experiment in both large and small scale.
Experimental Projects
1.
Using Light to Control Parametric Instability
High optical power gravitational wave detectors are likely to suffer parametric instability
due to the resonant interaction between the cavity optical modes and the high Q acoustic
modes of the test mass mirrors. This instability can be suppressed by feeding back optical
signals into the cavities. This project will investigate this idea of optical feedback control in
a small scale experiment. The research result will be in conjunction with experiments at the
Gingin High Optical Power Facility.
Parametric instability in a free optical cavity was first observed in a small scale table top
experiment in UWA lab. Then we observed the parametric instability in our 80m suspended
cavity. Shortly afterward, LIGO also observed parametric instability in the 4km
interferometer detector, with only 20% of the design optical power. It is of importance we
find effective control strategies to suppress and control the stability. One of them is to setup
an optical system to destructively interfere with the field inside the cavity to suppress the
instability. This will be achieved by reflect the cavity transmitted beam back into the cavity
after frequency shifting and phase masking. The reflected beam needs to be phase locked to
the cavity transmission to maintain correct phase to destructively interfere with the beam
inside cavity generated by the parametric process. The other is to use CO2 laser to modulate
the cavity parameters to suppress the parametric gain.
2.
Optical springs: towards measurements below the standard quantum limit
Optical springs are created by radiation pressure forces in optical cavities. This effect could
be used to modify the dynamics of the resonator/mirror in the optical cavity and thus
creating an opto-mechanical system with very low loss that could be used in a range of
schemes for beating the standard quantum limit for gravitational wave detectors.
This project will be focused on developing low loss
cavities with novel resonator design, and test optical
spring effect. We are collaborating with researchers
in Austria, Taiwan, Holland and France to fabricate
the “thermal noise free” resonators.
An
optomechanical system as shown in Figure 3 has
been designed. The project involves modelling the
resonator using finite element analysis, constructing
and tuning optical cavities to observe optical spring
dilution to achieve very low loss resonators. This Figure 3. An optical cavity with a
scheme has the potential of measuring macroscopic “cat-flap” resonator mirror design (the
objects with resolution better than the “standard purple part is the coated mirror)
quantum limit” predicted by naïve application of
quantum mechanics. This offers a new technique for improving gravitational wave detectors
as well as allowing a range of new experiments in quantum experiments.
Pictures of UWA optical laboratory table top opto-mechanics experiments and the 80m high optical power facility
Detecting Gravitational Wave Events - Data Analysis
The research group led by Prof. Linqing Wen aims at solving the most critical issues that the
entire gravitational wave community is facing, that is, how to best detect a gravitationalwave event and identify its electromagnetic counterpart in a timely manner.
The approach is to participate directly in the on-going international frontier research in the
gravitational-wave data analysis to (1) discover and (2) localize in real-time, possibly the
first gravitational-wave sources, (3) search for their electromagnetic (EM) counterparts
using both radio and optical telescopes, and (4) use theory of gravitation and data from
electromagnetic observations to probe the astrophysics of GW sources. Students with
proficiency in programming languages C and MATLAB are a plus.
The titles of the specific projects are:
1.
Real-time low-latency searches of gravitational waves from coalescing
binaries of neutron stars and black holes.
2.
Application of graphics processing units (GPUs) to speed up searches of
gravitational waves
3.
Probe of the parameter space of the gravitational-wave/X-ray source 4U
1820-30 using physics of 3-body dynamics, gravitation theory, and data
from electromagnetic observations
Probing the Transient Universe with a Robotic Telescope
This research group is led by David Coward (david.coward@uwa.edu.au) and
Ron Burman (ron.burman@uwa.edu.au).
The 21st century has heralded a new era in probing the Universe: for the first time mankind
is able to observe the Universe across all parts of the electromagnetic spectrum and beyond.
Space based gamma ray burst detectors have opened a window into a Universe teeming with
short-lived exotic phenomena, the so-called “transient Universe”.
The following projects will employ a new robotic telescope, the UWA Zadko Telescope, to
perform the following transient sky science:
1.
Probe the prompt optical emission of gamma ray bursts triggered by satellite
observatories, such as the NASA Swift satellite Swift and Fermi.
2.
Search for optical transients in coincidence with gravitational wave candidates
triggered from LIGO. A positive coincidence would significantly increase the
confidence of a gravitational wave detection.
3.
An Earth orbiting space debris identification and tracking program is
commencing.
Gamma Ray Bursts (GRBs)
GRBs are the brightest explosions in the Universe.
Theory and observation projects available using a robotic telescope network.
Projects involve collaborators in France
Space debris and satellite tracking
Space debris is a serious problem for all countries that rely on satellites for security,
communication and remote sensing.
The project will focus on developing dedicated software for tracking fast moving space
debris and will use the robotic Zadko Telescope.
For expressions of interest, please contact:
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Prof. David Blair david.blair@uwa.edu.au
A/Prof. Li Ju li.ju@uwa.edu.au
Dr. Chunnong Zhao chunnong.zhao@uwa.edu.au
Prof. Linqing Wen linqing.wen@uwa.edu.au
A/Prof. David Coward david.coward@uwa.edu.au
Scholarships
Australian and New Zealand citizens and Australian permanent residents are legible to apply
UWA post graduate Scholarship http://www.scholarships.uwa.edu.au/home/postgrad
International students can apply for International Postgraduate Research Scholarships (IPRS) and
Scholarships
for
International
Research
Fees
(SIRFs)
http://www.scholarships.uwa.edu.au/home/postgrad/international/iprs
Outstanding candidates in receipt of Australian Postgraduate Awards or University Postgraduate
Awards may be eligible to receive supplementary scholarships. Tutoring and part-time teaching
may also be available for additional income.
Academic visitors: Many of our PhD students first visit here as academic visitors. We have had
students and visitors from China, India, France, Chile, Austria, Poland, Singapore, Germany,
Romania and USA. Visitors usually receive living allowance equal to the value of a PhD
scholarship.