Publications (34)
Optical Continuum Reverberation Mapping of a Candidate IMBH in a Nearby Seyfert 1 Galaxy
Wenwen Zuo, Hengxiao Guo, Jingbo Sun +25
To investigate the short-term variability and determine the size of the optical continuum emitting region of intermediate-mass black holes (IMBHs), we carried out high-cadence, mul…
Real-time detection of an extreme scattering event: constraints on Galactic plasma lenses
Keith W. Bannister, Jamie Stevens, Artem V. Tuntsov +4
Extreme scattering events (ESEs) are distinctive fluctuations in the brightness of astronomical radio sources caused by occulting plasma lenses in the interstellar medium. The infe…
Spica and the annual cycle of PKS B1322-110 scintillations
Hayley Bignall, Cormac Reynolds, Jamie Stevens +9
PKS B1322-110 is a radio quasar that is located only 8.5' in angular separation from the bright B star Spica. It exhibits intra-day variability in its flux density at GHz frequenci…
Fermi LAT detection of two high Galactic latitude gamma-ray sources, Fermi J1049.7+0435 and J1103.2+1145
Masaki Nishimichi, Takeshi Okuda, Masaki Mori +2
The Second Fermi LAT source catalog (Nolan et al. 2012) includes as many as 1,873 sources, but initial attempts to identify counterparts at other wavelengths resulted in 575 source…
The second closest gamma-ray burst: sub-luminous GRB 111005A with no supernova in a super-solar metallicity environment
MichaÅ J. MichaÅowski, Dong Xu, Jamie Stevens +17
We report the detection of the radio afterglow of a long gamma-ray burst (GRB) 111005A at 5-345 GHz, including the very long baseline interferometry observations with the positiona…
Planetary Radio Interferometry and Doppler Experiment (PRIDE) technique: A test case of the Mars Express Phobos fly-by
Dmitry A. Duev, Sergei V. Pogrebenko, Giuseppe Cimò +33
The closest ever fly-by of the Martian moon Phobos, performed by the European Space Agency's Mars Express spacecraft, gives a unique opportunity to sharpen and test the Planetary R…
Extreme radio-wave scattering associated with hot stars
Mark Walker, Artem Tuntsov, Hayley Bignall +5
We use data on extreme radio scintillation to demonstrate that this phenomenon is associated with hot stars in the solar neighbourhood. The ionized gas responsible for the scatteri…
Scintillation kinks, bumps and wiggles in the radio spectrum of the quasar PMN J1106-3647
Artem V. Tuntsov, Jamie Stevens, Keith W. Bannister +4
We report radio observations of the quasar PMN J1106-3647. Our data, taken with the Australia Telescope Compact Array, show large variations in the amplitude and shape of its spect…
Dynamic spectral mapping of interstellar plasma lenses
Artem V. Tuntsov, Mark A. Walker, Leon V. E. Koopmans +5
Compact radio sources sometimes exhibit intervals of large, rapid changes in their flux-density, due to lensing by interstellar plasma crossing the line-of-sight. A novel survey pr…
Confirmation of the exclusive association between 6.7-GHz methanol masers and high-mass star formation regions
Shari Breen, Simon Ellingsen, Yanett Contreras +5
Recently, a comparison between the locations of 6.7-GHz methanol masers and dust continuum emission has renewed speculation that these masers can be associated with evolved stars.…
Detection of Crab Giant Pulses Using the Mileura Widefield Array Low Frequency Demonstrator Field Prototype System
N. D. Ramesh Bhat, Randall B. Wayth, Haydon S. Knight +14
We report on the detection of giant pulses from the Crab Nebula pulsar at a frequency of 200 MHz using the field deployment system designed for the Mileura Widefield Array's Low Fr…
Development of Radar and Optical Tracking of Near-Earth Asteroids at the University of Tasmania
Oliver James White, Guifré Molera Calvés, Shinji Horiuchi +9
We detail the use of the University of Tasmania's (UTAS) optical and radio telescopes to conduct observations of near-Earth asteroids from 2021 to 2024. The Canberra Deep Space Com…
Multi-wavelength Observations of PKS 2142-758 during an Active Gamma-Ray State
Michael Dutka, Roopesh Ojha, Katja Pottschmidt +10
PKS 2142-758 is a flat spectrum radio quasar which emits few, weak but significant gamma-ray flares in the MeV through GeV energy range. The first flare occured on April 4th, 2010,…
The Intermediate-Mass Black Hole Reverberation Mapping Project: Stable Optical Continuum Lags of an IMBH in the Dwarf Galaxy NGC 4395 Over Years
Yu Pan, Hengxiao Guo, Chenxu Liu +15
NGC 4395 is a nearby dwarf spiral galaxy hosting an active galactic nucleus (AGN) powered by an intermediate-mass black hole (IMBH, --). Re…
The first GeV flare of the radio-loud narrow-line Seyfert 1 galaxy PKS 2004-447
Andrea Gokus, Vaidehi S. Paliya, Sarah M. Wagner +8
On 2019 October 25, the Fermi-Large Area Telescope observed the first gamma-ray flare from the radio-loud narrow-line Seyfert 1 (NLSy 1) galaxy PKS 2004447 (). We report…
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…
The Murchison Widefield Array: Design Overview
Colin J. Lonsdale, Roger J. Cappallo, Miguel F. Morales +45
The Murchison Widefield Array (MWA) is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of sci…
Characterization of polarimetric and total intensity behaviour of a complete sample of PACO radio sources in the radio bands
Vincenzo Galluzzi, Marcella Massardi, Anna Bonaldi +17
We present high sensitivity (mJy) polarimetric observations in seven bands, from to GHz, of a complete sample of compact extragalactic radio so…
TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry. III. First-epoch S band images
Petra Benke, Florian Rösch, Eduardo Ros +10
With the emergence of very high energy astronomy (VHE; E>100 GeV), new open questions were presented to astronomers studying the multi-wavelength emission from blazars. Answers to…
The Intermediate-Mass Black Hole Reverberation Mapping Project: First Detection of Mid-Infrared Lags in Prototypical IMBHs in NGC 4395 and POX 52
Jingbo Sun, Hengxiao Guo, Wenwen Zuo +25
The search for robust evidence of intermediate-mass black holes (IMBHs) is crucial for understanding black hole seeding process and the formation of supermassive black holes in the…
Optical study of PKS B1322-110, the intra-hour variable radio source
Juan P. Madrid, Artem V. Tuntsov, Mischa Schirmer +7
Observations with the Australia Telescope Compact Array revealed intra-hour variations in the radio source PKS B1322-110 (Bignall et al. 2019). As part of an optical follow-up, we…
Discovery of Millimeter-Wave Excess Emission in Radio-Quiet Active Galactic Nuclei
Ehud Behar, Ranieri D. Baldi, Ari Laor +3
The physical origin of radio emission in Radio Quiet Active Galactic Nuclei (RQ AGN) remains unclear, whether it is a downscaled version of the relativistic jets typical of Radio L…
Fermi LAT detection of two high Galactic latitude gamma-ray sources, Fermi J1049.7+0435 and J1103.2+1145
Masaki Nishimichi, Takeshi Okuda, Masaki Mori +2
During a search for gamma-ray emission from NGC 3628 (Arp 317), two new unidentified gamma-ray sources, Fermi J1049.7+0435 and J1103.2+1145 have been discovered \cite{ATel}. The de…
1FGL J1417.7-4407: A likely gamma-ray bright binary with a massive neutron star and a giant secondary
Jay Strader, Laura Chomiuk, C. C. Cheung +12
We present multiwavelength observations of the persistent Fermi-LAT unidentified gamma-ray source 1FGL J1417.7-4407, showing it is likely to be associated with a newly discovered X…
First Spectroscopic Imaging Observations of the Sun at Low Radio Frequencies with the Murchison Widefield Array Prototype
Divya Oberoi, Lynn D. Matthews, Iver H. Cairns +67
We present the first spectroscopic images of solar radio transients from the prototype for the Murchison Widefield Array (MWA), observed on 2010 March 27. Our observations span the…
Field Deployment of Prototype Antenna Tiles for the Mileura Widefield Array--Low Frequency Demonstrator
Judd D. Bowman, David G. Barnes, Frank H. Briggs +22
Experiments were performed with prototype antenna tiles for the Mileura Widefield Array--Low Frequency Demonstrator (MWA-LFD) to better understand the widefield, wideband propertie…
First Detection of Radio Emission from the Intermediate Mass Black Hole in POX 52: Deep Multi-Band Observations with ATCA and VLA
Qi Yuan, Hengxiao Guo, Minfeng Gu +14
We present the first multi-band centimeter detection of POX 52, a nearby dwarf galaxy believed to habor a robust intermediate mass black hole (IMBH). We conducted the deep observat…
Astronomical verification of a stabilized frequency reference transfer system for the Square Kilometre Array
David Gozzard, Sascha Schediwy, Richard Dodson +7
In order to meet its cutting-edge scientific objectives, the Square Kilometre Array (SKA) telescope requires high-precision frequency references to be distributed to each of its an…
The Annual Cycle in Scintillation Timescale of PMN J1726+0639
Hayley E. Bignall, Artem V. Tuntsov, Jamie Stevens +3
We discovered rapid intra-day variability in radio source PMN J1726+0639 at GHz frequencies, during a survey to search for such variability with the Australia Telescope Compact Arr…
The TANAMI Multiwavelength Program: Dynamic SEDs of Southern Blazars
Felicia KrauÃ, Joern Wilms, Matthias Kadler +32
Simultaneous broadband spectral and temporal studies of blazars are an important tool for investigating active galactic nuclei (AGN) jet physics. We study the spectral evolution be…
The Spectral Behaviour and Variability of Narrow-line Seyfert 1 Galaxies with Australia Telescope Compact Array Observations
Xi Shao, Philip G. Edwards, Jamie Stevens +3
We present multi-frequency radio data for a sample of narrow-line Seyfert 1 galaxies. We first focus on the sub-class of gamma-ray emitting narrow-line Seyfert 1 galaxies, studying…
Star-Formation in the Ultraluminous Infrared Galaxy F00183-7111
Minnie Y. Mao, Ray P. Norris, Bjorn Emonts +5
We report the detection of molecular CO(1-0) gas in F00183-7111, one of the most extreme Ultra-Luminous Infrared Galaxies known, with the Australia Telescope Compact Array. We meas…
Multiband Observations of the Quasar PKS 2326-502 during Active and Quiescent Gamma-Ray States in 2010-2012
Michael S. Dutka, Bryce D. Carpenter, Roopesh Ojha +12
Quasi-simultaneous observations of the Flat Spectrum Radio Quasar PKS 2326-502 were carried out in the gamma-ray, X-ray, UV, optical, near-infrared, and radio bands. Thanks to thes…
Multi-Wavelength Observations of PKS 2142-75 during Active and Quiescent Gamma-Ray States
Michael Dutka, Roopesh Ojha, Katja Pottschmidt +13
PKS2142-75 (a.k.a. 2FGL J2147.4-7534) is a flat-spectrum radio quasar that was observed quasi-simultaneously by a suite of instruments across the elec- tromagnetic spectrum during…