UC Home > Departments > College of Science > Physics and Astronomy   

2010 Seminars

For specfic Medical Physics Seminars CLICK HERE

For specific Astronomy Seminars CLICK HERE

Scroll down to view general Department Friday Seminars by date

 

 

***********

20th December (Monday)

Dr. Robert Jedicke, University of Hawaii’s Institute for Astronomy

Killer Asteroids: Characterizing the Population with Spacewatch, Pan-STARRS and ATLAS

Not too long ago the idea that life on Earth has been profoundly affected by asteroid and comet impacts was viewed with disbelief bordering on disdain. But in the past few decades this attitude has been replaced by an international awareness of the danger posed to human life by these objects. The impact hazard is determined by the asteroids' and comets' orbit and size distribution and the best measurement of these properties for asteroids larger than about a half kilometer in diameter was performed almost a decade ago using observations of about 100 objects obtained with the 0.9-m Spacewatch telescope at Kitt Peak, Arizona The Pan-STARRS project in Hawaii expects to observe and discover thousands of these Near Earth Objects over the next few years which will allow a dramatic improvement in our understanding of the impact threat from large asteroids and comets.

The ATLAS project in Hawaii is a proposal to build the world's first early warning system to provide days to weeks notice of an impending impact of smaller objects that are not detected efficiently by deeper, large telescope asteroid surveys.

All Welcome!

***********

17th December

Dr Krzysztof Bolejko (Australian National University)

Homogenization of the early Universe: The present-day Universe appears to be homogeneous on very large scales. Yet when the casual structure of the early Universe is considered, it becomes apparent that the early Universe must have been highly inhomogeneous. The current paradigm attempts to answer this problem by postulating the inflation mechanism. However, inflation in order to start requires a homogeneous patch of at least the horizon size.
During my talk I will discuss how dynamical processes of the early Universe may lead to the pre-inflationary homogenization, making it possible for inflation to occur.

***********

3rd December

Angela D.V. Di Virgilio, INFN-Pisa (Italy)

Searching for gravitational waves (ground based detectors)
The ground based large interferometers for Gravitational Waves Detection are described, and the main results of the joint LIGO-Virgo runs reported. Second generation detectors, aLIGO and AdVirgo are ready to start the up-grating, which are expected to be ready in 2014. In one year of data with the expected sensitivity several events are expected, the first detection should be guaranteed, and the gravitation waves astronomy will start.

***********

Additional Seminar

Monday 29th November

Dr Hongsu Kim, International Center for Astrophysics, Korea Astronomy and Space Science Institute (KASI)
"Radio and Gravitational Wave Astronomy for the Black Holes in Galaxies"
It is now well known and widely accepted that almost all galaxies in the universe, regardless of their species (but most notably the AGNs), have, at their centers, the super massive, rotating black holes which exhibit variety of activities emitting both EM waves at all wavelengths and the illusive gravitational wave. In the present talk, we would like to introduce the theoretical predictions and discuss the hopes and difficulties associated with the observations of the theoretical predictions regarding the study of such super massive spinning black holes.

************

26 November

Professor Sergei Gulyaev, Director, Institute for Radio Astronomy and Space Research, School of Computing and Mathematical Sciences, Auckland University of Technology

SKA capability development in New Zealand: Radio Astronomy: The Square Kilometre Array (SKA) is the world’s greatest radio telescope, to be built in the Southern Hemisphere in 2016-2025. New Zealand is one of 19 nations working on this mega-science project and one of three countries that may eventually co-host the SKA. The development of radio astronomy in New Zealand stretches back to 1940s when Elisabeth Alexander discovered the “Norfolk effect” and John Bolton and Gordon Stanley for the first time identified “radio stars” with optical galaxies and SNRs. The new stage in New Zealand radio astronomy started in 2005 with successful “very long baseline interferometry” (VLBI) observations between the 6-m Brent Addis’ radio telescope (BART) and Australian radio telescopes, which obtained the first NZ radio map of Sgr A. Erection of the first professional 12-m radio telescope in Warkworth allowed broadening the spectrum of radio astronomical observations dramatically.

Here I report on recent spectroscopic observations of interplanetary spacecraft, determination of the He abundance in the ISM from radio recombination lines, single-dish observations of HII regions and SNRs, VLBI observations of the radio galaxy (Cen A), quasar (PKS 1934-638) and X-ray binary star (Circinus X-1). The role of radio astronomy in geosciences (eg tectonic plate monitoring and earthquake prediction) is discussed. An important announcement will be made, and future steps in New Zealand development towards SKA outlined.

*******************

 

19th November

Prof Ulrich (Ulli) Schreiber,
Federal Agency of Surveying and Mapping (BKG), Technische Universitaet Muenchen (TUM), University of Canterbury (UC)

Recent progress in Sagnac Interferometry: The G ring laser at the Geodetic Observatory in Wettzell was designed and constructed in a joint initiative between UC, TUM and BKG. The demanding goal was to develop this measure¬ment concept to the point where it is contributing to Space Geodesy in the same way like the established techniques i.e. Satellite Laser Ranging (SLR), Very Long Baseline Interferomtry (VLBI). Over the last year we have improved the system by almost one order of magnitude in sensitivity and by more than one order of magnitude in stability. In the process a number of geophysical phenomena became accessible to a Sagnac interferometer for the first time. This talk will outline the current status of Sagnac interferometry.

*******************

Thursday 11 November

Xinzhao Chu
Associate Professor, Department of Aerospace Engineering Sciences Fellow, Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder

McMurdo – the next stop for lidar research of atmosphere

Lidar stands for light detection and ranging or laser radar, a very powerful tool for atmosphere science studies. A pole-to-pole lidar expedition has been made with an iron (Fe) Boltzmann lidar that we developed to study the middle and upper atmosphere from the North Pole to the South Pole. This lidar was deployed to the South Pole (90 S) and then to the Rothera (67.5 S), Antarctica from 1999 to 2005. Numerous data were collected and several interesting scientific discoveries emerged. This lidar is now on its way to McMurdo (78 S), aiming to complete an observational chain in the Antarctic. It will be installed in the Kiwi’s laboratory at the Arrival Heights this summer and expected to operate there for at least three years. In this seminar we will introduce several interesting results and discuss the unique topics of polar atmosphere studies that we can do through collaboration with Dr. Adrian McDonald’s group.

*******************

5th November

Dr Melanie Johnston-Hollitt(Part 1), & Dr Slava Kitaev (Part 2), New Zealand Square Kilometre Array (SKA),

Future New Zealand Activities in Radio Astronomy: Building Capability for the Square Kilometre ArrayNew Zealand has been through a recent expansion of interest and capability building in radio astronomy. This expansion is driven by national interest in the Square Kilometre Array and has been underpinned by new research groups being established, NZ-based researchers taking leading roles in international radio surveys and research teams, development of novel signal processing techniques and successful new trans-Tasman VLBI experiments.

We present an update on the NZ-wide advances in the field of Radio Astronomy and Radio Engineering with a particular focus on contributions, which hope to either directly or indirectly contribute to New Zealand's engagement with the international Square Kilometre Array (SKA) project. We further discuss the status of the SKA project in New Zealand.

Part 2: The statistical characteristics of transient radio sky are largely unknown. The possible origin of predicted transients include annihilating primordial black holes, colliding neutron stars, supernovas, magnetars, RGB and possibly some other exotic objects which are yet to be observed. Without understanding of the processes unfolding on very short time scale and likely with very large release of energy our understanding of the Universe is incomplete.

New and planned large radio telescopes such as MWA, ASKAP, SKA and others will have the capacity to study transient sky; however the techniques are yet to be developed. Small inexpensive experiments targeting detection of bright transients over the large areas of sky can help to develop such techniques, and at the same time according to various speculations allow detecting a few per year or even per day events. Transient Radio Emission Array Detector (TREAD) is a collaborative effort of several NZ stakeholders aiming to develop such new technique and study transient radio sky. The difficult issue of discriminating genuine transient from man-made interferences generally requires avoiding the interferences as much as possible. Our study shows the unique qualities of Mackenzie Country for these purposes.

About the speaker
Dr Slava Kitaev received his integrated BS/MS from Urals State University in 1990. He received his PhD in the field of radio astronomy and instrumentation from P.N. Lebedev Physical Institute of Russian Academy of Sciences in 1998. From 1987 till 2001 he was with Pushchino Radio Astronomy Observatory near Moscow working in the field of interstellar medium using one of the largest European radio telescopes DKR-1000 and also leading a technical group developing computing and data transport technologies for radio astronomy. After a short “industry” break in Germany, Dr Kitaev arrived to NZ and joined the School of Engineering @ AUT in 2003. Since then he played a significant role in activating SKA and radio astronomy research in NZ. Dr Kitaev is a founding member of Executive Committee of NZ SKA R&D Consortium.

*************

EXTRA SEMINAR

Tuesday, 2nd November

Dr Nicole Bell, Senior Lecturer, Theoretical Particle Physics, University of Melbourne.

"Indirect Detection of Dark Matter"

We discuss prospects for indirect detection of dark matter, via dark matter annihilation or decay in our Galaxy. We consider the production of gamma rays, neutrinos, or electron/positron final states, and use observational data to constrain the dark matter annihilation or decay processes in a model independent way. We discuss the implication of our bounds for models which seek to use annihilation or decay to modify the structure of dark matter halos, or remedy small scale structure problems.

We also examine radiative corrections to the lowest order decay/annihilation modes, namely bremsstrahlung and electroweak-bremsstralung, and describe scenarios in which they which make important (and in some cases, dominant) contributions to the observable fluxes. We discuss these annihilation/decay modes in light of recent cosmic ray positron and antiproton data.

*************

22nd October

No seminar scheduled.

**********

15th October

Professor Roger J. Reeves, Department of Physics and Astronomy , University of Canterbury.

Indium nitride and zinc oxide: what is special about these two semiconductors at opposite ends of the spectrum: For the last several years a large component of my research programme has been the study of two semiconductors of emerging interest – InN and ZnO.  InN is a key component of the blue and green optical emitters (eg LED’s) that have transformed aspects of lighting and displays.  ZnO on the other hand has yet to be successfully incorporated into a product other than sunblock or nappy cream! Somewhat serendipitously these two materials are fundamentally very difficult to make with p-type conductivity which appears to be a limitation to their development.
This seminar will be a gentle introduction to these materials, why they are thought to have significant commercial opportunities, and what contributions to their understanding are being made from our research.

**********

8th October

Anthony Brown Postdoctoral Fellow, Physics and Astronomy Department, University of Canterbury

Gamma-ray astronomy – probing the extreme environments with extreme radiation

Very High Energy (VHE) gamma-rays represent the highest energy photons detected so far. Emitted through non-thermal processes, these energetic photons allow us to explore some of the most extreme environments within the Universe, thus permitting us to study the laws of physics in conditions we cannot recreate in the lab. In short, VHE gamma-ray emission requires charged particles of the same energy, if not more. Therefore, VHE gamma-ray observations are a key diagnostic tool in our understanding of the most energetic particles in the Universe. Recent improvements in gamma-ray telescope sensitivity has resulted in an explosion of discoveries from the VHE gamma-ray community over the last few years. These discoveries have shown VHE gamma-ray source types to range from exploding stars, to binary systems, to neutron stars, to super-massive black holes to the unknown. In this talk we discuss some of the exciting results from the field of ground based gamma-ray astronomy.

******

1st October

Peter Smale PhD student, Physics and Astronomy Department, University of Canterbury

Standard Candle Tests with Type 1a Supernovae
Type 1a supernovae (SNe Ia) are thermonuclear explosions powerful enough to be visible over redshifts of up to 2. Although the exact mechanism of their generation is still a matter of debate, their physics is sufficiently uniform and well understood for them to be used as standard candles.  In probing such length scales, SNe Ia observations provide a testing ground for the cosmological models that describe the large-scale behaviour of the universe. The discovery that the expansion of the universe is accelerating is due to the development of SNe Ia cosmology: they are the most direct probes we have into physics beyond the standard cold dark matter model.
This talk describes how SNe Ia are used as standard candles. I will describe their photometric and spectral features and how the observed fluxes and redshifts are converted to distances. Then I will discuss some of the systematic uncertainties that make supernova cosmology something of a black art. For example, they offer an opportunity to investigate the nature and distribution of dust in other galaxies, and there is an interesting degeneracy in some light curve fitters between treatment of extinction due to host galaxy dust and the possibility that we live in a local void.

 

*******

24th September

Pubudu Senanayake PhD student, Physics and Astronomy Department,University of Canterbury

Spectrally and temporally resolved emission of the CaF2:Yb2+ exciton: As the demand for energy increases globally, one of the primary uses of energy is lighting. As such the importance of having efficient lighting devices is self evident. Rare earth doped materials are a possible candidate for use in such devices as they have very high quantum efficiency. To this end research is being undertaken here at the University of Canterbury to understand such systems. This talk will focus on the anomalous emission observed in CaF2:Yb2+, a result of a bound exciton with energy levels between the 4f - 5d levels of Yb.
For the first time, such a structure has been directly probed, using a Free Electron Laser (FEL) - with a tunable wavelength range from 5 to 250 m - after initial excitation into the exciton state using a pulsed UV laser. We have observed emission peaking in the excitation wavelength range of 12 to 26 m and 30 to 50 m, in agreement with theoretical calculations. Temporally we have observed the lifetimes of the exciton states to be around 250m and on the order of 10 ms.

A rate equation model has so far been able to reproduce these results with some success.

*******

17th September

Seminar Cancelled.

*******

10th September [cancelled due to earthquake]

Peter McLeish [Peter McLeish's tour of New Zealand is undertaken with the support of the Canadian High Commission in Wellington]

A Collaboration based on Red Sprites: Peter McLeish will discuss the nature of his collaboration based on Red Sprites.
Red sprites are upper atmospheric optical phenomenon associated with thunderstorms that have recently been only documented using low level television. The first images of a sprite were taken in 1989 and from 1990 to 1994 the space shuttle obtained twenty more images. Despite nearly a century of anecdotal reports from airline pilots, most scientists didn't really believe in sprites until the first images were captured on high-speed video. The blink of an eye last 250 milliseconds: sprites often last only ten. Cameras and computer models freeze sprites in time.
Since 2001, Peter has been involved in a collaboration based on Red Sprites with American scientist Walter A. Lyons. This collaboration eventually led to Walter A. Lyons receiving a Unites States National Science Foundation grant regarding the collaboration and subsequent creation of Lyons’s DVD titled The Hundred Year Hunt for Red Sprites and interactive website. Peter created the artwork in the The Hundred Year Hunt for Red Sprites as well as his companion-six minute film titled Lightning’s Angels. Since 2002, both films have been presented at many major International science symposiums, conferences, media festivals, science film festivals, science & art museums/centres and planetariums all over the world. Peter’s continued research subsequently led him to an additional collaboration with Dr. Colin Price from the Department of Geophysics and Planetary Science, Tel Aviv University who was working on sprite research from a ground station with the ill-fated crew of the Columbia in 2003. Since 2007, Peter has been working on a new project titled Polaris Terrarum about the Polar Regions.

*******

3rd Sepetember

Dr. Geoff Willmott, Industrial Research Limited (IRL), Lower Hutt, The MacDiarmid Institute

Nanofluidics: Plumbing New Depths: The Nano and Micro Fluidics team at IRL is broadly involved in development of next-generation diagnostic devices. Current research topics include materials and methods for manufacturing disposable devices, and efficient on-chip identification methods for amino acids and rare cells, for example.

This talk will describe related efforts to extend conventional microfluidics to the nanoscale. The overall aim of this research is to develop and understand a series of practical tools for nanofluidic 'plumbing'. Small fluid volumes are not turbulent, so fluid motion is reasonably predictable, but other important effects emerge at small length scales. Examples include non-zero surface slip, significant surface charge, and the geometry of practical nanoscale structures. Three areas of research will be detailed:
i) Sensing of particles as they pass through a nanopore filled with aqueous electrolyte. This work utilizes tunable nanopores, drawing on our collaboration with Izon Science (Christchurch).
ii) Interactions between droplets and microfluidic capillary tubes.
iii) Theoretical predictions regarding non-zero surface slip on curved surfaces (in general) and Janus particles (in particular).

(This will be an updated version of the recent MacDiarmid Institute seminar, which didn’t make it to Christchurch due to a videoconferencing meltdown.)

*******

27th August

Dr Natalie Plank, School of Chemical and Physical Sciences, Victoria University of Wellington

ZnO nanowires for low cost solar cell applications: Solid-state dye-sensitised solar cells (SDSCs) are a promising technology for energy applications due to their low cost fabrication methods and the use of low toxicity materials.  One of the key advantages of SDSCs is that the resulting devices are lightweight, can be "flexible" and transparent in certain wavelength ranges, making solar cells useful for a wide-range of applications. Here work is presented on the facile synthesis of ZnO nanowires for SDSCs.  In general the power conversion efficiency for ZnO nanowire solar cells has been routinely lower than the TiO2 nanoparticle counter parts however, the two materials are similar and ZnO should show improved conduction performance.  I will describe methods developed to improve the charge transfer into the ZnO nanowires, using MgO and ZrO2 shell deposition techniques, to control the interface between the organic dyes and the ZnO in SDSCs.

 

*******

20th August

Ishwaree Neupane, Royal Society University Fellow with the Physics and Astronomy Department University of Canterbury.

We Probably Live in an Inflating Brane-World
The universe endows with a number of cosmological mysteries but the one that most vex physicists is the discovery made over a decade ago from observations of distant supernovae that the expansion of the universe is currently accelerating. This cosmological conundrum has so far defied an elegant and forthright explanation.

There is a large gamut of gravitational theories that can explain a period of accelerated expansion of the universe with certain modification of the standard Einstein gravity in four dimensions. The issue of cosmic acceleration (attributed to dark energy) is, however, not about the difficulty of finding a particular cosmological model which could mimic as the Lambda-CDM model, described by Einstein gravity with a positive cosmological constant and minimally coupled to both the luminous (baryonic) and non-luminous (cold dark) matter. The challenge is to come up with a fully consistent theory of four-dimensional cosmology that explains the origin of the cosmological constant and/or the source of cosmic acceleration, while providing insights into some other major problems in physics, including the mass hierarchy problem in particle physics and the origin of the three large physical dimensions.

Brane-world models, where observers are restricted to a brane in a higher-dimensional spacetime, offer a novel perspective on cosmology. In this talk, I would argue that the problem of cosmological constant is well explained within the framework of a four-dimensional de Sitter universe embedded in a five-dimensional de Sitter spacetime.

********

13th August

No Seminar - Physics and Astronomy Dept a.m. tea with PVC in Coppertop

********

6 August 2010

Prof J. S. Gallagher
Department of Astronomy, University of Wisconsin-Madison Erskine Visiting Fellow

Exploring the Astrophysics of Intense Star Formation in Starburst Galaxies
Nearby starburst galaxies provide opportunities to explore the astrophysics of intense modes of star formation operating on galactic scales. Multiwavelength observations of such systems demonstrate that as star formation moves from being isolated events, as are typical of the disks of spiral galaxies, to closely spaced and thus strongly interacting regions, energy densities in the interstellar gas rise dramatically. Conditions in the nearest two major starburst galaxies, M82 and NGC253, illustrate the basic issues associated with these circumstances, including high thermal pressures conducive to formation of dense star clusters, extensive high temperature gas feeding substantial galactic winds, and extreme fluxes of cosmic rays. In this talk I will review how we are beginning to measure conditions in starbursts and briefly discuss their astrophysical implications for feedback processes in galaxies, as well as for the future of multi-messenger observations, such as those now getting under way with IceCube.

 

********

30 July 2010

Sebastian Horvath, Postgraduate Student, Physics and Astronomy Department, University of Canterbury

Relativity of Darkness: This talk is about dark matter and its relativity in the sense of self-referential darkness versus relative darkness. Beyond that, this is a talk about the symmetries of the event space underling dark matter. A hundred years after Einstein we learn that the constancy of the speed of light suggests special relativity only as one of the choices. Dark matter seems to fit very naturally within the other options.

********

23rd July 2010

D. V. Ahluwalia, Department of Physics and Astronomy, (University of Canterbury

Neutrinos: New Hints of New Physics: From their birth neutrinos have been conceptually enigmatic particles. In the middle of June, a few weeks ago, in Athens something extraordinary happened. One experiment reported possible violation of CP, while the other indicated that CPT itself may be violated. I’ll review these experimental findings and suggest that things may not be what they appear to be and that CP and CPT may still survive but something as simple as energy conservation — the concept that gave birth to these particles — may be responsible for these new effects through an EPR-like quantum entanglement.

*********

16 July 2010

Dr Philip Catton, Department of Philosophy, School of Humanities, University of Canterbury

Diagram, analysis, motion, and rigour: Pappus, Newton, Hilbert, Dirac: Neither what mathematical analysis is, nor how it may be supposed to possess rigor, are for Isaac Newton quite the questions that subsequent history shaped them to become. Newton for his part answers these questions in a manner that furthers a perspective on analysis — due to Pappus of Alexandria — as creative, diagrammatic work. Historically key for aptly understanding Newton, this perspective is also telling philosophically, in a way that tells against orthodoxy concerning the needed qualities of a “rigourisation” of mathematical analysis. Orthodoxy much reflects pure mathematicians’ nineteenth-century “rigourisation” of the calculus, an effort that sent the diagram from the fore of pure mathematics to the rear. I shall briefly consider in relation to physics the upshot of this in polymath mathematician David Hilbert, for Hilbert’s “sixth problem” concerned physics. Finally I examine Paul Dirac, to illustrate that even in the darkest hour for diagrams, at a time when mathematicians forsook them utterly and even physicists (such as Dirac) made a secret of their use, physicists (such as Dirac) nonetheless depended upon them crucially for their reasoning.

 

*********

9th July 2010

*********

2 July 2010

*********

25 June 2010

Dr Peter Renaud, Mathematics and Statistics Dept, University of Canterbury

Clifford algebra: Use and abuse in physics and engineering: The use of Clifford algebra in mathematical physics and engineering has grown in recent years. In engineering, it has found applications in robotics and more generally, in rigid body motion. In physics, (sometimes in disguised form) it is virtually a necessity in describing electron spin, as spinors cannot be constructed by tensor methods in terms of exterior powers of the vector space.

Clifford algebra has both an algebraic and a geometric flavour. The latter is the more difficult to understand, but the most rewarding. 
(Anyone can do algebra.) In this talk we will concentrate on the geometric side of Clifford algebra and how this might give us added insight, not only into the solution of a problem, but also into the problem itself.

Some inflammatory, and mostly irrelevant, remarks about what constitutes a good mathematical theory will be offered.

*********

18 June 2010

UC Break -

*********

11 June 2010

Dr Justin Hodgkiss,
MacDiarmid Institute for Advanced Materials and Nanotechnology , School of Chemical and Physical Sciences, VUW on Illuminating the operation of organic solar cells using laser spectroscopy

Printable organic solar cells offer the potential to realize the goal of competitively priced solar energy. However, they are currently restricted in their application owing to poor efficiency, particularly resulting from charge recombination. We have developed transient absorption spectroscopy techniques to resolve each step of organic solar cell operation spanning over nine decades in time resolution – from light absorption to charge collection or recombination. For a range of polymer: polymer and polymer: fullerene devices, interfacial charge transfer is resolved across heterojunctions on a picosecond timescale and related to nanometer scale phase separation. Overall, we find that the efficiency of subsequent interfacial charge pair dissociation is the key determinant of device efficiency. This work draws from a range of materials and blend morphologies to generalize strategies for improved charge separation and help inform the route to cost-effective photovoltaic power generation. 

*******************

4th June 2010

Dr Stuart Ryder
Australian Gemini Office, Anglo-Australian Observatory, Sydney, Australia

Where are all the Missing Supernovae? Despite the dedicated efforts of amateur and robotic searches, the number of supernovae discovered each year is only a lower limit to the actual number of supernovae that occur. The supernova rate is potentially the most direct way of tracing the star formation history of the Universe.
In this talk I will describe our ongoing effort to find supernovae which would otherwise have gone unnoticed, in particular using laser guide star adaptive optics on the Gemini North telescope to find supernovae in Luminous Infrared Galaxies. I will also discuss the contribution that the Square Kilometre Array radio telescope, in which Australia and New Zealand are involved, can make to this effort.
Bio: Stuart Ryder graduated with 1st class Honours in Astronomy from the University of Canterbury in 1988. He undertook his PhD studies at the Mt Stromlo and Siding Spring Observatories of the Australian National University, graduating in 1993. After postdoctoral appointments at the University of Alabama, the University of New South Wales, and the Joint Astronomy Centre in Hawaii, he joined the staff of the Anglo-Australian Observatory in 1999. He is currently the head of the Australian Gemini Office, which coordinates Australia's usage of large offshore telescopes including the Gemini 8m telescopes in Hawaii and Chile, and the twin Magellan 6.5m telescopes in Chile.

*********************

Friday 28th May

No Seminar today

*********************

11:00 a.m. Friday 21st May

Assoc Prof Charles Hellaby, University of Cape Town,
Erskine visitor in the Physics and Astronomy Department from 26 April - 4 June 2010

The Geometry and the Mass of the Cosmos
Einstein's field equations say that gravity is not a force, it is the curvature of spacetime.  They relate the spacetime geometry and curvature to the matter distribution.  The ultimate application of Einstein's equations would be to deduce the geometry of the cosmos from observations of its matter content.  I describe progress towards a method for doing this, and some of the difficulties involved.  As cosmological observations become more accurate, detailed knowledge of our cosmic geometry will be needed.  Standard models assume homogeneity, but can we test this with new or future observations?  Cosmological observations are limited to the past null cone: the speed of light means we only see each galaxy, cluster, etc at a fixed time in the past.  Because of this, a homogeneous universe does not look homogeneous, and this makes it tricky to verify.

***************

11:00 a.m. Thursday 20th May

Special STAR Talk - CANCELLED SPEAKER WAS STRANDED IN AUCKLAND DUE TO FOG

Dr Slava Kitaev, Director, Institute for Industrial Innovation AUT University, Auckland

Universe at High Time Resolution: Search for Radio Transients

We tend to think that astronomical events unfold on the time scales of millions of years or at least a few days. Some theories and latest evidences suggest that it might be incomplete view of the Universe, and some events may unfold on a time scale on nanoseconds as a release of truly astronomical amount of energy. They would appear to us as "one off" transient burst of electromagnetic emission. The statistical characteristics of transient radio sky are largely unknown yet. I will talk about the reasons why they are unknown as well as about hypothetical phenomena we might be still missing to observe. I will be also discussing Transient Radio Emission Array Detector project as our recent attempt to develop techniques for detection of fast radio transients and how this work contributes to the SKA effort.
 
Bio: Dr Slava Kitaev holds a PhD in radio astronomy from P.N.Lebedev Physical Institute of Russian Academy of Sciences. He was a part of Pushchino Radio Astronomy Observatory of Astro Space Centre for 13 years where he led a research group on radio astronomy computation methods. He's spend a few years working in ICT industry in Germany prior coming to New Zealand. Dr Slava Kitaev has been currently with the School of Engineering of AUT University for 7 years, where he's been elected as Director of Centre for Reconfigurable Systems. He also serves on Executive Committee of NZ SKA R&D Consortium. His research interests are broadly in radiophysics, radio astronomy methods and instrumentation. He leads TREAD collaborative project, which will be the main focus of his talk.

 

*********************

11:00 a.m. Friday 14th May (joint seminar between Physics & Astonomy and Electrical and Computer Engineering Dept's).

Professor Veit Elser, Physics Department, Cornell University

Erskine Fellow from the Physics Department, Cornell University, visiting with the Department of Electrical and Computer Engineering

A solution strategy for hard problems inspired by the x-ray phase problem
This talk describes a style of computation inspired by the "phase problem" of x-ray crystallography and recent efforts to test its scope in other applications. The method seems especially well suited for problems with many non-linear constraints. Among the applications described in the talk is a problem that goes back to Aristotle: the packing of regular tetrahedra.

***********

11:00 a.m. Friday 7th May

Dr William Lee
Centre for Quantum Computing Technology, University of New South Wales

Nanoscale devices using STM lithography for quantum computing applications
Scaling down of Si based electronic devices is essential both for classical computing according to Moore’s Law and to tap into the powerful quantum regime in quantum computing applications. One approach is via STM lithography where the atomic resolution of scanning tunneling microscopy is utilized for the fabrication of nanoscale devices. In this talk, the basic process of this novel fabrication technique will be explained and its application to quantum computing will be explored.

 

***********

11:00 a.m. Friday 30th April

Denis J Sullivan, Victoria University of Wellington

The Physics of White Dwarf Stars: White Dwarfs are compact stellar objects with very high mass densities. The fact that their observed luminosities are relatively low, given their measured surface temperatures, was established about 100 years ago and this was the first indication of their unusual properties.  White dwarfs are slowly cooling stellar remnants, corresponding to the end product of the evolutionary changes in the vast majority of stars.  In several distinct temperature regimes they are unstable to pulsation, and the consequent luminosity variations can be detected and exploited to probe otherwise hidden stellar structure and properties. The speaker has spent several decades (mostly using the Mt John one metre telescope) investigating pulsating white dwarfs using this technique (referred to as Asteroseismology).  White dwarfs provide a unique cosmic laboratory for exploring a range of exotic physics, and the speaker will discuss a number of these topics.

************

11:00 a.m. Friday 23rd April

Terry Peters, PhD FCCPM, FAAPM, FIEEE, FInstP
Robarts Research Institute, University of Western Ontario, London, Canada

Image-guided, Minimally-invasive Interventions in the Brain and Heart: Surgical procedures often have the unfortunate side-effect of causing the patient significant trauma while accessing the target site. Indeed, in some cases the trauma inflicted on the patient during access to the target greatly exceeds that caused by performing the therapy. Over the years we have developed techniques that rely on pre-operative mages, combined with data acquired during the procedure for performing minimally-invasive surgery on the brain and heart. 
This presentation will illustrate this work with respect to its application for both deep-brain stimulator implantation as well as intra-cardiac therapy. For Deep-brain therapy for Parkinson's tremor, we map a database of deep-brain electrophysiological responses to the patient's brain.  Guided by these data and intra-operatively acquired electrophysiology measurements, the target region is approached with a stimulating electrode through a small burr-hole in the skull to select the final target. In the heart, many intra cardiac interventions are currently performed after the chest has been opened, the patient placed on cardiopulmonary bypass, and the heart arrested. Our approach is to register intra-operative images to the patient, and use a navigation system that combines intra-operative ultrasound with virtual models of instrumentation that has been introduced into the chamber through the heart wall.

*********

11:00 a.m. Friday 16th April

Scott Palo, Visiting Erskine Fellow University of Colorado, Department of Aerospace Engineering Science

Solar Forced Thermal Tides in the Atmosphere:- While gravitationally forced lunar tides generate significant amplitude periodic oscillations in the global oceans the corollary is not true for the atmosphere. In fact the lunar tides in the atmosphere are quite small in comparison to the thermally forced solar tides. These atmospheric tides are forced by the periodic absorption of solar radiation in the infra-red by water vapor in the troposphere and the ultraviolet by ozone in the stratosphere. Conserving energy and propagating vertically through the atmosphere these waves can reach significant amplitudes of 30-50 m/s in the horizontal wind field and 10-20K in the temperature field of the mesosphere before breaking or dissipating. This provides a mechanism for the redistribution of energy throughout the atmosphere.

In this talk I will provide a brief overview of the solar forced atmospheric tides, results from current modelling efforts and discuss recent observations from space and also those made from our meteor radar at the South Pole.

**********

11:00 a.m. Friday 9th April

 

**********

3:00 p.m. (extra seminar), Friday 26th March

Rob Lewis, Monash University

New Insights in Medicine from X-ray Physics:
X-rays have been used for medicine for over 100 years and their use continues to increase dramatically.
Modern X-ray facilities such as the Imaging and Medical Beamline of the Australian Synchrotron enable new methodologies that are yielding new insights into physiology and disease.
For example, lung diseases are one of the leading causes of death in adult humans. These diseases commonly result in pathologies within the distal airways that are challenging to detect, especially during the early stages when treatments are likely to be most efficacious. To address this problem, we have combined synchrotron phase contrast x-ray imaging with particle image velicometry to create a method capable of producing time resolved tomographic vector maps of lung motion in live animals. The technique is capable of detecting subtle variations in the motion of regions of the lung. Since many diseases affect the mechanical behaviour of lung tissue it is believed that changes in the lung motion will be a predictor of disease.
This and other examples will be presented on the way that X-ray physics continues to play a significant role in medical research.

 

******************

11:00 a.m. Friday 26th March

Prof Geoffrey C. Clayton
Professor of Physics & Astronomy, Louisiana State University,Department of Physics & Astronomy, Baton Rouge, LA, USA.
The Evolutionary History of the R Coronae Borealis Star
The R Coronae Borealis (RCB) stars are rare hydrogen-deficient carbon-rich supergiants, all apparently single stars which are consistent with being post-AGB stars. RCB stars undergo massive declines of up to 8 mag due to the formation of carbon dust at irregular intervals. The mechanism of dust formation around RCB stars is not well understood but the dust is thought to form in or near the atmosphere of the stars. Their rarity may stem from the fact that they are in an extremely rapid phase of the evolution or in an evolutionary phase that most stars do not undergo. Several evolutionary scenarios have been suggested to account for the RCB stars including, a merger of two white dwarfs (WDs), or a final helium shell flash in a PN central star. The large overabundance of 18O found in most of the RCB stars favors the WD merger scenario while the presence of Li in the atmospheres of four of the RCB stars favors the FF scenario. In particular, the measured isotopic abundances imply that many, if not most, RCB stars are produced by WD mergers, which may be the low-mass counterparts of the more massive mergers thought to produce type Ia supernovae. I will present recent visible and IR observations of various RCB stars obtained with HST, Spitzer and ground-based telescopes.

Background on Geoffrey C. Clayton

My research involves the study of dust in various astrophysical environments:  circumstellar, interstellar and extragalactic. I am studying how dust grain properties change from quiescent cloud to star-forming cloud to circumstellar environments. With my collaborators, I am modeling dust on microscopic and macroscopic scales to determine the role of dust in the energy budget of these various environments. We use extinction, polarization, abundance and spectroscopic observations from the UV to the IR for the same sightlines obtained from Hubble and Spitzer Space Telescopes as well as other space- and ground-based telescopes. The goal is to produce a unified model of dust which will satisfy observational constraints from all wavelengths (UV to IR) in these different environments using the DDA and MEM codes. To this end we are investigating Radiative Transfer in circumstellar, star formation and extragalactic environments. The capabilities of our Monte Carlo codes include, scattering, radiative equilibrium solutions, emission from PAHs, and scattering from aligned grains. These codes produce spectra, images, and polarization (images and spectra) for comparison with observations.

*********************

Friday, 19th March

Philip Yock, University of Auckland

Gravitational microlensing and plasma wakefield acceleration:The process of gravitational microlensing enables astronomical measurements to be made with modest telescopes that are not possible using conventional astronomical techniques. Stars may be resolved with resolutions greatly exceeding the resolution of the Hubble Space Telescope, extra-solar planets may be detected orbiting stars as far away as the Galactic centre, and isolated black holes may be detected. Examples of these applications will be briefly described.
 
The process of plasma wakefield acceleration offers the prospect of carrying out new experiments in particle physics at very high energies on the table-top with modest equipment. Particles may be accelerated thousands of times more rapidly in simple lithium-filled cells than is achieved in present-day particle accelerators. Examples of possible applications of the technique will be briefly described.   

 

**************

Friday, 12th March

Cancelled for Dept Photo

************

Friday, 5th March

Dr Duncan Wright, (former UC PhD student), Post Doctoral Fellow, Royal Observatory of Belgium

 The analysis of time-series spectroscopic data of stars undergoing non-radial pulsation

A time-series of visual range spectroscopic data is used for examining the pulsation parameters in a variety of non-radially pulsating stars. I will discuss the methods used for analysing these multi-site data sets, the results being obtained from them, and how they can be useful in the days of ultra-high precision space-satellite photometry.

***

Friday, 26 February 2010

James Burnett (University College London)

Elko spinors -- A source of dark energy and torsion?
In this talk I will give a brief introduction to the relatively new Elko spinor, discussing its defining properties. We will see that due to its definitions, it is naturally ``dark'' and as result suggests it as a good candidate for dark matter. Furthermore I will demonstrate that as a bonus the Elko spinor could be used to also explain dark energy. Finally I will introduce the properties of a universe which includes torsion (Einstein-Cartan) showing that Elko spinors could act as a source of torsion in the early universe which quickly decays to agree with today’s observation of zero torsion. I will endeavour to keep the first half free of equations, going into more detail in the second part.

***************

Friday 19th February 2010

P.D. Nicholson
Department of Astronomy, Cornell University

Cassini at Saturn: Rings, Atmosphere and Moons: Since Saturn orbit insertion on July 1, 2004, instruments on the Cassini orbiter have been observing the planet, its rings, Titan and several of the icy satellites. I will briefly review some of the highlights of these observations, concentrating on optical and near-infrared imaging. Saturn's main rings have been imaged and scanned in unprecedented detail, revealing density waves and "wakes" driven by nearby and embedded satellites, evidence for unresolved 100-meter-sized moonlets and subtle, large-scale compositional variations.  Mosaics show the complex, kinky, multi-stranded structure of the F ring, while images taken in the planet's shadow show two new, extremely tenuous rings.  Saturn itself sports a complex, ever-changing pattern of ring shadows, as well as several giant thunderstorms, ultraviolet aurorae and a mysterious hexagonal feature at the north pole.  Studies of the planet's radio emissions seem to show that its rotation period has lengthened by about 5 min since 1981.

The surface composition of the large moon Titan remains enigmatic, partly due to our very limited ability to see through its thick, methane-rich atmosphere outside of a few narrow `windows'. However, significant albedo variations exist in the near-IR which may correspond to elevated regions dominated by water ice and lower areas covered by dark, probably organic material.  Recent radar images have revealed what appear to be "lakes" in the far north, while the equatorial regions are dominated by immense dune fields and occasional sinuous channels reminiscent of terrestrial rivers.  Although smaller than Jupiter's Galilean satellites, Saturn's icy moons turn out to be equally intriguing. Icy plumes erupt from Enceldus' south polar region, feeding the tenuous E ring, while chaotically-tumbling Hyperion has a surface texture similar to coral. Enigmatic Iapetus shows evidence of ancient giant impacts, as well as more recent geologic activity. Distant Phoebe, likely a captured Kuiper belt object, is heavily-cratered with a much more chemically-diverse surface than the inner satellites.  This work was supported by NASA under a contract with the Cassini-Huygens Project.

 

Friday, 12th February 2010

Professor John Hearnshaw, Professor of Astronomy, Department of Physics and Astronomy, UC

Auguste Comte’s blunder:  An account of the first century of stellar spectroscopy and how it took one hundred years to prove that Comte was wrong!: In 1835 the French philosopher Auguste Comte predicted that we would never know anything about the chemical composition of stars. In this talk I will give a broad overview of the development of stellar spectroscopy, especially from about 1860. Developments in stellar spectroscopy segregated quite clearly into three main fields of endeavour: spectral classification, radial velocities and spectral analysis. After introducing the main players, I will concentrate mainly on spectral analysis, or how stellar spectroscopy one hundred years after Comte showed that quantitative information on the composition of stars was possible. The journey on the way was quite arduous, as it required numerous developments in theoretical physics and in laboratory spectroscopy first to take place, which in turn allowed stellar spectral analysis successfully to be undertaken by the mid-20th century.
The key developments in physics that first had to be understood were in quantum and atomic theory, ionization theory, the concept of the Planck function, local thermodynamic equilibrium, the first stellar model atmospheres, line formation theory, turbulence, collisional broadening of spectral lines and the theory of radiative transfer and of the curve of growth. My talk will emphasize these close links between stellar spectroscopy and theoretical physics. In addition laboratory physics was also an essential precursor, to measure line wavelengths and oscillator strengths.
Comte may have been an influential philosopher of science in the nineteenth century. Perhaps his one small transgression was not to have read the works of Joseph Fraunhofer, which in the early 19th century already contained the first small clues that Comte’s assertion might be wrong.

 

 

*******************

Friday, 5th February 2010

Dr Chris Blake, Visitor in the Department from Swinburne University, Melbourne, Australia

Cosmology with the WiggleZ Dark Energy Survey
The WiggleZ Survey is a large-scale galaxy redshift survey which has been in progress at the Anglo-Australian Telescope for 3 years.  I will describe our current measurements of the distribution of galaxies to high redshift, how they trace the expansion of the Universe and the growth of cosmic structure, and what this can tell us about the physical laws governing the Universe.