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ATNF
Student Symposium 2002
First Session Chair: Erik Muller
9.15am Welcome
9.20am Daniel Mitchell
RFI Mitigation: Adaptive Filters
9.40am Catherine Drake
Radio­Excess IRAS Galaxies
10.00am Natasa Vranesevic
Pulsar Birthrate
10.20am Aaron Chippendale
Imaging With Many Baseline Synthesis Interferometry
10.35am Brad Warren
The Nature of Nearby High HI Mass­to­Light Ratio Field Galaxies
10.50am Co#ee
Second Session Chair: Daniel Mitchell
11.10am Emma Ryan­Weber
What does HI gas in galaxies tell us about Lyman­alpha absorption systems?
11.30am Erik Muller
A statistical look at the morphology of HI in the Magellanic Bridge
11.50am Meryl Waugh
HI in the Fornax Region
12.10pm Jess O'Brien
UGC7321 ­ A Pure Disk Galaxy in the Process of Bulge Formation
12.30pm Lunch

Abstracts
Daniel Mitchell
RFI Mitigation: Adaptive Filters
In radio astronomy real­time adaptive filters (and their post­correlation equivalents) can be used to model
the RFI environment so that it can be cancelled from the astronomy signal path. I will describe a modi­
fied filter which utilises an additional reference signal to improve the RFI excision. The trade­o# is that
the injected noise of the new filter is stronger than the total residual of the standard filter. I will compare
residual RFI and injected noise levels with that of the standard filter and the post­correlation approach.
An example from the Australia Telescope Compact Array is also given.
Catherine Drake
Radio­Excess IRAS Galaxies
A sample of radio­emitting active galaxies has been identified by selecting objects from the IRAS Faint
Source Catalog which lie above the FIR/radio correlation. These radio­excess galaxies have radio emis­
sion which is likely to be associated with an AGN, but many do not fit the traditional classification
of radio­loud. ATCA observations show the majority of the radio sources to be compact and to have
steep spectral indices. They are similar to Compact Steep Spectrum and GigaHertz Peaked Spectrum
sources, though lower in radio power. The galaxies in our sample are highly luminous in the far infrared
(log(L) > 11 solar luminosities), comparable with Ultra­Luminous Infrared Galaxies. Optical imaging
shows that many have disturbed morphology, suggesting that tidal interactions are responsible for the
high FIR luminosities of these objects and may also be associated with fuelling the radio source. My PhD
study involves radio and optical observations of the sample which will be used to determine the nature
of these FIR­luminous radio­excess galaxies. Preliminary results from the observations and analysis will
be presented and discussed.
Natasa Vranesevic
Pulsar Birthrate
How to find and explain the valid statistical methods aimed at deriving the initial spin periods and
birthrate of pulsars?
Aaron Chippendale
Imaging With Many Baseline Synthesis Interferometry
Brad Warren
The Nature of Nearby High HI Mass­to­Light Ratio Field Galaxies
One of the first products of the HI Parkes All­Sky Survey (HIPASS), the first ever survey of extragalactic
HI over the southern sky, is the HIPASS Bright Galaxy Catalogue (BGC) listing the 1000 apparently
brightest HI sources. A comparison of the newly available HI data with the optical properties of the BGC
galaxies revealed an interesting number (50) of high HI mass­to­light ratio (M/L > 3) intrinsically faint

field galaxies. We are undertaking an extensive multi­wavelength follow­up (optical, infrared and radio)
of a selected sample of these galaxies and comparing them to a similar sample of low HI mass­to­light
ratio galaxies. We hope to identify the physical reasons why some dwarfs still consist mainly of primordial
HI gas, whereas others have processed most of their gas into stars.
Emma Ryan­Weber
What does HI gas in galaxies tell us about Lyman­alpha absorption systems?
I will discuss the association of HI gas in galaxies with Lyman­alpha absorption systems. Firstly, through
a measurement of column density distribution function at z=0 using 21­cm emission. This study used the
ATCA to measure column density in galaxies selected from the HI Parkes All Sky Survey. We find that the
likelyhood of intersecting a lyman­alpha absorption system with column density 19.1 # log N HI # 20.3
is a relatively flat function of galaxy HI mass and morphology. This implies that moderate to Damped
Lyman­alpha absorption systems may be caused by a galaxies with a range of HI masses, morphologies
and luminosities ­ not just large spiral galaxies as originally thought. In addition I will describe a pro­
posed study to cross correlate HI detections in HIPASS with lyman­alpha absorption systems from the
literature. Preliminary analysis suggests that the strength of absorption may be a stronger function of
local galaxy density rather than the impact parameter to the nearest galaxy
Erik Muller
A statistical look at the morphology of HI in the Magellanic Bridge
Recent ATCA + Parkes observations of the HI line emission region comprising the western Magellanic
Bridge show a complex filimentary, clumpy and chaotic nature. This Kinematic and spatial data indicate
that SMC material dominates this part of the Bridge. We present results of analyses of the powerspec­
trum (PS) variation with velocity thickness, and results of the Specral Correlation Functin (SCF) tool.
The SCF confirms a more persistant East­West spatial correlation of HI spectra in the Bridge, an e#ect of
the tidal stretching forces imposed on the Bridge. The Bridge HI data show similar power spectra slopes
to that of the SMC, although a di#erent behaviour of Power law slope variation with velocity increments.
These suggest the HI of the Bridge and SMC occupy a similar spatial scale range, but a di#erent velocity
dispersion range.
Meryl Waugh
HI in the Fornax Region
My current research project has involved a search of HIPASS data in a 620 sq. deg. region centred on
the Fornax Cluster. In HI, the cluster is seen as only as a marginal overdensity of galaxies, unlike the
distribution of optical galaxies. However, we have found that the cluster is part of the nearby large­scale
structure, being embedded in a sheet of HI galaxies running through the region. We are interested in
elucidating any di#erences between gas­rich galaxies in the cluster, looser groups and the field and in
studying the processes and influences which may be responsible for these di#erences. Two deeper, blind,
''basketweave'' surveys of 100 sq. deg. each have also been undertaken using the Parkes telscope. The
first survey field is centred on the cluster and the second field is about 10 deg north, a region without
obvious clustering. These data are not fully analysed as yet but several low peak flux galaxies have been
confirmed which were not detected in HIPASS.
Jess O'Brien
UGC7321 ­ A Pure Disk Galaxy in the Process of Bulge Formation