Publications (29)
Local Column Density Distribution Function from HI selected galaxies
Emma Ryan-Weber, Rachel Webster, Lister Staveley-Smith
The cross-section of sky occupied by a particular neutral hydrogen column density provides insight into the nature of Lyman-alpha absorption systems. We have measured this column d…
AllBRICQS: the All-sky BRIght, Complete Quasar Survey
Christopher A. Onken, Christian Wolf, Wei Jeat Hon +3
We describe the first results from the All-sky BRIght, Complete Quasar Survey (AllBRICQS), which aims to discover the last remaining optically bright quasars. We present 156 spectr…
Recycling of ghost galaxies: The origin of giant HI ring around NGC 1533
Kenji Bekki, Warrick J. Couch, Emma Ryan-Weber +1
We propose that the giant HI ring recently discovered by HIPASS for S0 galaxy NGC 1533 is formed by unequal-mass merging between gas-rich LSB (low surface brightness: ``ghost'') ga…
Near-infrared micro-variability of radio-loud quasars
Matthew Whiting, Alicia Oshlack, Rachel Webster
We observed three AGN from the Parkes Half-Jansky Flat-spectrum Sample at near-infrared (NIR) wavelengths to search for micro-variability. In one source, the blue quasar PKS 2243-1…
Broad-line Active Galactic Nuclei in the 6dF Galaxy Survey
Wei Jeat Hon, Rachel Webster, Christian Wolf
The Six-degree Field Galaxy Survey (6dFGS) is a spectroscopic redshift survey of the Southern hemisphere completed in 2006. While it provides 136,304 spectra of mostly low-redshift…
OzSSy1: The Australian Southern Seyfert-1 Spectroscopic Atlas and Catalogue at z < 0.1
Neelesh Amrutha, Christian Wolf, Christopher A. Onken +3
We present a spectroscopic atlas of 887 broad-line active galactic nuclei (AGNs) in the Southern sky, spanning redshifts , declinations deg and Galactic latitudes…
The Column Density Distribution Function at z=0 from HI Selected Galaxies
Emma Ryan-Weber, Rachel Webster, Lister Staveley-Smith
We have measured the column density distribution function, f(N), at z=0 using 21-cm HI emission from galaxies selected from a blind HI survey. f(N) is found to be smaller and flatt…
Cosmological Obscuration by Galactic Dust: Effects of Dust Evolution
Frank Masci, Rachel Webster
We explore the effects of dust in cosmologically distributed intervening galaxies on the high redshift universe using a generalised model where dust content evolves with cosmic tim…
Loan and nonloan flows in the Australian interbank network
Andrey Sokolov, Rachel Webster, Andrew Melatos +1
High-value transactions between Australian banks are settled in the Reserve Bank Information and Transfer System (RITS) administered by the Reserve Bank of Australia. RITS operates…
The Neutral Hydrogen Properties of Galaxies in Gas-rich Groups
Robert Džudžar, Virginia Kilborn, Gerhardt Meurer +23
We present an analysis of the integrated neutral hydrogen (HI) properties for 27 galaxies within nine low mass, gas-rich, late-type dominated groups which we denote "Choirs". We fi…
Astro2020 Science White Paper - Quasar Microlensing: Revolutionizing our Understanding of Quasar Structure and Dynamics
Leonidas Moustakas, Matthew O'Dowd, Timo Anguita +20
Microlensing by stars within distant galaxies acting as strong gravitational lenses of multiply-imaged quasars, provides a unique and direct measurement of the internal structure o…
The Fundamental Manifold of spiral galaxies: ordered versus random motions and the morphology dependence of the Tully-Fisher relation
Chiara Tonini, Heath Jones, Jeremy Mould +3
(Abridged) We investigate the morphology dependence of the Tully-Fisher relation, and the expansion of the relation into a three-dimensional manifold defined by luminosity, total c…
Galactic Recycling: The HI Ring Around NGC 1533
Emma Ryan-Weber, Rachel Webster, Kenji Bekki
We report the discovery of a new HI ring around the S0 galaxy NGC 1533. The ring orbits at a radius of 35 kpc, well outside the optical extent of the galaxy. We have conducted N-bo…
Serendipitous discovery of a dying Giant Radio Galaxy associated with NGC 1534, using the Murchison Widefield Array
Natasha Hurley-Walker, Melanie Johnston-Hollitt, Ron Ekers +41
Recent observations with the Murchison Widefield Array at 185~MHz have serendipitously unveiled a heretofore unknown giant and relatively nearby () radio galaxy associa…
Fast Holographic Deconvolution: a new technique for precision radio interferometry
Ian Sullivan, Miguel Morales, Bryna Hazelton +48
We introduce the Fast Holographic Deconvolution method for analyzing interferometric radio data. Our new method is an extension of A-projection/software-holography/forward modeling…
SkyMapper colours of Seyfert galaxies and Changing-look AGN-II. Newly discovered Changing-look AGN
Wei Jeat Hon, Christian Wolf, Christopher Onken +2
Changing-look Active Galactic Nuclei (CLAGN) are AGN that change type as their broad emission lines appear or disappear, which is usually accompanied by strong flux changes inn the…
The Most Powerful Lenses in the Universe: Quasar Microlensing as a Probe of the Lensing Galaxy
David Pooley, Timo Anguita, Saloni Bhatiani +14
Optical and X-ray observations of strongly gravitationally lensed quasars (especially when four separate images of the quasar are produced) determine not only the amount of matter…
NOIRCAT - The Northern HIPASS Optical/IR Catalogue
O. Ivy Wong, Rachel Webster, Virginia Kilborn +2
We present the Northern HIPASS Optical/InfraRed CATalogue (NOIRCAT), an optical/near-infrared counterpart to the Northern HIPASS catalogue (NHICAT). Of the 1002 sources in NHICAT,…
Optical Variability Structure Function of Low-Luminosity AGN using ATLAS Lightcurves
Ashley Hai Tung Tan, Christian Wolf, Neelesh Amrutha +3
The origin of the optical flux variability in active galactic nuclei (AGN) is largely unknown. Previous studies have correlated features of the variability structure function (SF)…
Black Hole Mass Estimates of Radio Selected Quasars
Alicia Oshlack, Rachel Webster, Matthew Whiting
The black hole (BH) mass in the centre of AGN has been estimated for a sample of radio-selected flat-spectrum quasars to investigate the relationship between BH mass and radio prop…
A Very Radio-Loud Narrow-Line Seyfert 1: PKS 2004-447
Alicia Oshlack, Rachel Webster, Matthew Whiting
We have discovered a very radio-loud Narrow-Line Seyfert 1 candidate: PKS 2004-447. This Seyfert is consistent with the formal definition for NLS1s, although it does not have quite…
The Murchison Widefield Array Commissioning Survey: A Low-Frequency Catalogue of 14,110 Compact Radio Sources over 6,100 Square Degrees
Natasha Hurley-Walker, John Morgan, Randall B. Wayth +49
We present the results of an approximately 6,100 square degree 104--196MHz radio sky survey performed with the Murchison Widefield Array during instrument commissioning between 201…
The Optical Emission from Gamma-ray Quasars
Matthew Whiting, Petra Majewski, Rachel Webster
We present photometric observations of six radio-loud quasars that were detected by the COMPTEL gamma-ray telescope. The data encompasses seven wavebands in the optical and near-in…
Luminosity distance dispersion in Swiss-cheese cosmology as a function of the hole size distribution
Thippayawis Cheunchitra, Andrew Melatos, Rachel Webster
The luminosity distance-redshift (--) relation derived from Type Ia supernovae (SNe Ia) yields evidence for a nonzero cosmological constant. SNe Ia analyses typically…
Choirs, HI Galaxy Groups: Catalogue and Detection of Star-forming Dwarf Group Members
Sarah M. Sweet, Gerhardt Meurer, Michael J. Drinkwater +24
Hα observations centred on galaxies selected from the HI Parkes All Sky Survey (HIPASS, Barnes et al. 2001) typically show one and sometimes two star-forming galaxies within the a…
Thermal infrared characterization of spatially unresolved resident space objects: Prospects from analytical two-component modeling
Stephen Catsamas, Sarah Caddy, Michele Trenti +5
In this work we investigate the potential of a thermal infrared (IR) space telescope to remotely characterize the component temperatures of a satellite. With the rapid increase in…
Discovering Changing-Look AGN in the 6dF Galaxy Survey using ATLAS Light curves
Neelesh Amrutha, Christian Wolf, Christopher A. Onken +4
Changing-Look Active Galactic Nuclei (CLAGN) are characterised by extreme variations in line emission over short timescales, mostly affecting broad H lines. While a few hundred…
Evidence for an intermediate-mass black hole from a gravitationally lensed gamma-ray burst
James Paynter, Rachel Webster, Eric Thrane
If gamma-ray bursts are at cosmological distances, they must be gravitationally lensed occasionally. The detection of lensed images with millisecond-to-second time delays provides…
The low-frequency characteristics of PSR J0437-4715 observed with the Murchison Widefield Array
N. D. Ramesh Bhat, S. M. Ord, S. E. Tremblay +37
We report on the detection of the millisecond pulsar PSR J0437-4715 with the Murchison Widefield Array (MWA) at a frequency of 192 MHz. Our observations show rapid modulations of p…