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The following projects are available for the 2009 Summer Vacation Program. You may select up to three projects in order of preference on your application form.
Project 1: Faraday rotation in the Galactic interstellar medium
Discipline: Astrophysics
Supervisor: Dr Dominic Schnitzeler (ATNF), Dr Bryan Gaensler (University of Sydney)
Location: Sydney
Description: In this project we investigate the properties of the magnetic field of the Milky Way. When a radio wave travels through the ionized gas in the Milky Way, the Galactic magnetic field will rotate its plane of polarization, an effect known as Faraday rotation. Faraday rotation has been used extensively in the past to study the strength and orientation of the magnetic field both in our own Galaxy and in external galaxies. It turns out that magnetic fields play an important role in the evolution of galaxies, on small scales, where clouds of gas and dust collapse to form stars, up to scales that encompass the entire galaxy. However, at this point it is still unclear how the large-scale ordered fields that we observe arise. A better understanding of the interaction between the magnetic field and the ionized gas is crucial for this, and there is no better place where we can study this interaction in detail than the Milky Way.
Here we will develop a data reduction strategy and data reduction pipeline to look for Faraday rotation in bright Australia Telescope Compact Array (ATCA) calibrator sources. The first step in this project will be to retrieve the ATCA archival data of suitable calibrator sources. We will then modify the pipeline that Dominic wrote to analyze ATCA CABB data to determine the amount of Faraday rotation towards each of these calibrators. The lessons that we learn during this process can help us to develop the polarization pipeline for ASKAP. Depending on how quick our progress is, this might produce a few 100s of new Faraday rotation measurements. Finally, we will combine these new measurements with existing catalogues to study Faraday rotation in the Galactic interstellar medium.
If you're interested in this project, and you'd like to know more, then you can contact Dominic at Dominic.Schnitzeler@atnf.csiro.au
You can find some background information in Schnitzeler et al. 2006 - Fig. 1 dramatically illustrates the importance of Faraday rotation in the Milky Way! Gaensler et al. (2005) and Mao et al. (2008 ApJ 688) nicely show how Faraday rotation in extragalactic sources can be used to study the magnetic field strength and orientation in foreground objects - in this case the Large and Small Magellanic Clouds.
Project 2: Discovering candidates for Galactic magnetic field studies
Discipline: Astrophysics
Supervisor: Dr James Green
Location: Sydney
Description:An ideal way to gain fundamental insight into the magnetic fields of
our Galaxy is through the observations of astrophysical masers (radio
wavelength equivalents of lasers) made towards targets in the spiral
arms. In the near future the Australia Telescope Compact Array, with
its new correlator, and the Long Baseline Array will be used to
determine the magnetic fields of ground-state hydroxyl masers through
the Zeeman splitting effect. This will allow us to see if the magnetic
fields present in the spiral arms are consistent with the rotation of
our Galaxy. We are looking for a student to analyse recent Compact
Array observations to help discover new hydroxyl masers. The student
will also have the chance to explore single dish polarimetric data for
ideal candidates. This project offers the opportunity to gain an
understanding of the effect of magnetism in the interstellar medium,
and the findings will be used to establish a prioritised and extensive
catalogue of hydroxyl masers for magnetic field studies.
Project 3: Evolution of the host galaxies of active super-massive black-holes
Discipline: Astrophysics
Supervisors: Dr Bjorn Emonts
Location: Sydney
Description: Active Galactic Nuclei (AGN) are among the most energetic phenomena in the Universe and are created when gas and matter is accreted onto a super-massive black-hole in the centre of the host galaxy. In some cases, powerful radio continuum jets are expelled from the black-hole region, which can exert major feedback onto the gas in the central region of the galaxy. The processes responsible for the onset of this AGN activity are still somewhat ambiguous, but gas-rich galaxy mergers or interactions have often been invoked as possible triggering mechanisms.
Studying the cool neutral hydrogen (HI) gas is an excellent way to investigate the origin and evolution of the AGN host galaxy and connect this to the nuclear activity. While the distribution of the large-scale HI emission-line gas may show long-lived evidence for galaxy mergers or interaction (in the form of tidal-tails, -bridges and -discs), extreme kinematics of HI gas detected in absorption in front of the strong central radio continuum can reveal evidence for jet-driven outflows (AGN feedback) or gas infall (AGN fuelling). This summer-student project focuses on mapping the neutral hydrogen (HI) gas in a nearby radio galaxy that is known to be unusually rich in cool gas. Aim is to investigate whether a recent galaxy merger or interaction occurred in this system and whether the radio jets interact with the surrounding gas. HI data recently obtained with the Westerbork Synthesis Radio Telescope is available for this project.
The project is part of a larger ongoing HI study on the connection between AGN activity and galaxy evolution. Emphasis will be on learning the principles of radio astronomy, reducing and analysing new HI data in MIRIAD, understanding the results in a broader context of galaxy evolution and presenting these results in a scientific way (possibly including the preparation of a scientific paper). We are looking for an enthusiastic candidate with a great interest in extra-galactic and/or observational astronomy.
Project 4: Variability and Transients in ATLAS
Discipline: Astrophysics
Supervisor: Dr Ray Norris and Dr George Hobbs
Location: Sydney
Description: In most areas of radio-astronomy, we usually assume that the
sources don't change much with time. So in the Australia Telescope
Large Area Survey (ATLAS) project (see http://www.atnf.csiro.au/
research/deep), in which we are probing deep into the extragalactic
Universe to understand the origin and evolution of galaxies, we've
blithely added together thousands of hours of data taken over the
last 3 years. However, we know that active galactic nuclei (AGN),
which are powered by gas falling into black holes, frequently vary
on timescales of days to months, and about half the sources in
ATLAS are AGN. A quick look has already shown that some of our
galaxies seem to be varying like this. So the primary goal of this
project is to detect and study this variability, and see what it
can tell us about the sources. Even more exciting is the discovery
of transient bursts of radio emission of unknown origin elsewhere
in the sky (e.g. Lorimer et al. 2007, Science 318, 777), which has
alerted us to the fact that we ought to be looking for fast time-
variability too. So this vacation project will have the goal of
mining the ATLAS data to search for variability in the radio emission.
This is a speculative project, because nobody's ever tried this in a survey like ATLAS before, and so we really don't know what we'll find. The outcomes of the project might include the following: (a) Almost certainly we will see some of our radio sources fluctuate as a function of time. Such variability in extragalactic sources is already well-known, but nobody has studied it in a sample like ATLAS to see how this variability depends on the galaxy type, redshift, etc., and what this might tell us about the massive black holes that power these galaxies. (b) There's an outside chance we might find a burst of radio emission like that found by Lorimer et al., which might be due to a completely new phenomenon.
The first job in this project will be to take the raw data from the telescopes, and use the Miriad software to subtract off all the radio sources that we already know about. We will then take two approaches to analyse the data. To look for new transient sources, we will be make images from short sequences of subtracted data, to see if any unexpected sources pop up. To search for variability in known sources, we will plot the amplitude as a function of time at the positions of the known sources. The goal is that, within the timescale of the project, a paper will be submitted to an international refereed journal. The project will also include opportunities to participate in the ATLAS observations on the Australia Telescope Compact Array.
Project 5: The environment of high-mass star forming regions
Discipline: Astrophysics
Supervisor: Dr Maxim Voronkov
Location: Sydney
Description: A birth of a massive star is a violent process which has a significant impact on the
environment of the gas clouds where such stars are formed. The outflows of gas produce
an enormous change in the chemical composition of the medium surrounding the newly
formed star giving rise to emission of many molecular species which can easily be detected
with the modern radio-telescopes. When the massive star is finally turned on, it
creates a bubble of ionised gas known as HII region in its immediate vicinity.
We are looking for a student interested in working with the radio data from the revolutionary new
broad-band backend of the Australia Telescope Compact Array (called CABB). The main part of the
project will involve investigating the structure and kinematics of some selected regions of high-mass
star-formation using molecular and radio-recombination spectral lines as well as the continuum
emission at millimetre wavelengths.
Project 6: Searching for a pulsar-black hole binary system with the
World's largest radio telescopes
Discipline: Astrophysics
Supervisors: Dr George Hobbs and Dr Ray Norris
Location: Sydney
Description:Almost 2000 rapidly rotating neutron stars (known as 'pulsars') have now been discovered. Some of these pulsars have had a huge impact on
astronomy and astrophysics. For instance, the first extra-Solar planets were discovered around a pulsar, the first evidence of ripples in the fabric of spacetime (gravitational waves) were found using a pulsar orbiting another neutron star and the most stringent tests of general relativity have been carried out using pulsar observations. Almost all of these pulsars were discovered using a large telescope such as the Parkes radio telescope in Australia. New telescopes are now being designed and built that should discover many pulsars. It is challenging to carry out standard pulsar searches using these new telescopes and so we are considering a new survey method that piggy-backs on surveys for distant galaxies. This new technique may provide the first detection of very exciting systems such as a pulsar orbiting a black hole. As part of this project, you will process existing data from telescopes such as the Molonglo and Compact Array telescopes and study the signatures of known pulsars
in these data sets. Understanding these properties will allow you to search for undiscovered (and hopefully very exciting) pulsars in these observations.
Project 7: Revealing star formation processes in dwarf starburst galaxies
Discipline: Astrophysics
Supervisor: Dr Ángel López-Sánchez
Location: Sydney
Description: Some dwarf galaxies host very intense star-formation bursts, are
dominated by metal-poor young stars and still possess a lot of neutral
gas. They are called "Blue Compact Dwarf Galaxies" (BCDGs) and it is
thought they were very common in the primitive universe. The origin and
the nature of the starbursts is still poorly understood but perhaps they
are consequence of interaction between dwarf objects, as hierarchical
galaxy formation model predict. In the last years we have compiled many
multi-wavelength data of a sample of BCDGs, including Compact Array HI
and radio-continuum observations. We are looking for a student to work
in the radio-continuum data of these galaxies, specifically obtaining
and analyzing 20-cm radio-continuum maps. These maps will be used to
derive an extinction-free star formation rate to compare with that
obtained from the Halpha flux. The student may also help in the analysis
of the neutral gas component in one particular system, comparing the
star formation rate per area and the mean surface density of cold gas to
check if the Schmidt-Kennicutt star-formation law is also satisfied in
these dwarf objects. All these analysis, combined with those obtained
using optical imagery and spectroscopy, will get key clues to understand
the trigger mechanism of the BCDGs and describe their dynamical and
chemical evolution.
Project 8: Characterising Energetic Pulsars with the Parkes Radio Telescope
Discipline: Astrophysics
Supervisor: Dr Simon Johnston and Dr Mike Keith
Location: Sydney
Description: The ATNF pulsar group has been regularly observing 167 highly energetic radio pulsars at the Parkes radio telescope, in conjunction with the Fermi Gamma-Ray Space Telescope. Our observations use the technique of pulsar timing to make precision measurements of the spin properties and the other behaviour of these enigmatic neutron stars. We are looking for a summer student to help with the observations at Parkes and to analyse the results to understand how these pulsars spin and the interstellar medium that lies between us and each pulsar. By the end of this project you will understand how pulsars work at radio and gamma-ray wavelengths and be well versed in observational radio astronomy.
Project 9: Public Presentation and Primary Resources for Astronomy Outreach
Discipline: Outreach: Science Communication & Education
Supervisor: Chris Hollingdrake & Rob Hollow
Location: Parkes Observatory
Description: Working at the Visitors Centre at the Parkes radio telescope in the Central West of NSW you will tackle two aspects in this project. The first is to develop an informative and engaging presentation on astronomy for the public visiting the observatory. You will then present this during the holiday season at the Visitors Centre and interact with the public. The second task is to develop a resource booklet on Parkes and radio astronomy suitable for primary aged school children visiting the observatory. This project is ideally suited to someone studying science education or communication, preferably with an interest in astronomy. Experience in public speaking or presenting and knowledge or experience in science resource development is required. Knowledge of Astronomy advantageous but not essential. The successful applicant must be available to work over the Christmas period at Parkes.