K. W. Bannister

Commonwealth Scientific and Industrial Research Organisation

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Co-Authors

R. M. Shannon

Swinburne University of Technology

C. James

Curtin University

Tara Murphy

University of Sydney

Adam T. Deller

ARC Centre of Excellence for Gravitational Wave Discovery

Shivani Bhandari

Commonwealth Scientific and Industrial Research Organisation

Jean‐Pierre Macquart

Curtin University

J. X. Prochaska

University of California, Santa Cruz

E. Lenc

Australia Telescope National Facility

S. D. Ryder

Macquarie University

M. E. Bell

University of Technology Sydney

Cooperative Institutions

Centre National de la Recherche Scientifique

726

California Institute of Technology

624

Goddard Space Flight Center

384

Max Planck Society

313

Consejo Nacional de Investigaciones Científicas y Técnicas

289

Université Paris Cité

271

Commonwealth Scientific and Industrial Research Organisation

269

Australian National University

263

Astronomy and Space

256

Cardiff University

243

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The Australian Square Kilometre Array Pathfinder: System Architecture and Specifications of the Boolardy Engineering Test Array

Publications of the Astronomical Society of Australia (2014)

A. W. Hotan John D. Bunton Lisa Harvey-Smith B. Humphreys Brian D. Jeffs

This paper describes the system architecture of a newly constructed radio telescope - the Boolardy Engineering Test Array, which is a prototype of the Australian Square Kilometre Array Pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a 6-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least 9 dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.

Pathfinder

Square (algebra)

Sensor array

10.1017/pasa.2014.36

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Citations (78)

An X-ray and UV flare from the galaxy XMMSL1 J061927.1-655311

Astronomy and Astrophysics (2014)

R. D. Saxton A. M. Read S. Komossa P. M. Rodríguez-Pascual G. Miniutti

Aims. New high variability extragalactic sources may be identified by comparing the flux of sources seen in the XMM-Newton Slew Survey with detections and upper limits from the ROSAT All Sky Survey.

ROSAT

Flare

10.1051/0004-6361/201424347

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Citations (17)

The impact of the FREDDA dedispersion algorithm on H0 estimations with FRBs

Monthly Notices of the Royal Astronomical Society (2024)

J. Hoffmann C. James Hao Qiu Marcin Glowacki K. W. Bannister

Fast radio bursts (FRBs) are transient radio signals of extragalactic origins that are subjected to propagation effects such as dispersion and scattering. It follows then that these signals hold information regarding the medium they have traversed and are hence useful as cosmological probes of the Universe. Recently, FRBs were used to make an independent measure of the Hubble Constant $H_0$, promising to resolve the Hubble tension given a sufficient number of detected FRBs. Such cosmological studies are dependent on FRB population statistics, cosmological parameters and detection biases, and thus it is important to accurately characterise each of these. In this work, we empirically characterise the sensitivity of the Fast Real-time Engine for Dedispersing Amplitudes (FREDDA) which is the current detection system for the Australian Square Kilometer Array Pathfinder (ASKAP). We coherently redisperse high-time resolution data of 13 ASKAP-detected FRBs and inject them into FREDDA to determine the recovered signal-to-noise ratios as a function of dispersion measure (DM). We find that for 11 of the 13 FRBs, these results are consistent with injecting idealised pulses. Approximating this sensitivity function with theoretical predictions results in a systematic error of 0.3$\,$km$\,$s$^{-1}\,$Mpc$^{-1}$ on $H_0$ when it is the only free parameter. Allowing additional parameters to vary could increase this systematic by up to $\sim1\,$km$\,$s$^{-1}\,$Mpc$^{-1}$. We estimate that this systematic will not be relevant until $\sim$400 localised FRBs have been detected, but will likely be significant in resolving the Hubble tension.

10.1093/mnras/stae131

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Citations (3)

Radio variable and transient sources on minute time-scales in the ASKAP pilot surveys

Monthly Notices of the Royal Astronomical Society (2023)

Yuanming Wang Tara Murphy E. Lenc Louis Mercorelli L N Driessen

We present results from a radio survey for variable and transient sources on 15-min timescales, using the Australian SKA Pathfinder (ASKAP) pilot surveys. The pilot surveys consist of 505 h of observations conducted at around 1 GHz observing frequency, with a total sky coverage of 1476 deg$^2$. Each observation was tracked for approximately 8-10h, with a typical rms sensitivity of $\sim$30 $\mu$jy/beam and an angular resolution of $\sim$12 arcsec. The variability search was conducted within each 8-10h observation on a 15-min timescale. We detected 38 variable and transient sources. Seven of them are known pulsars, including an eclipsing millisecond pulsar, PSR J2039$-$5617. Another eight sources are stars, only one of which has been previously identified as a radio star. For the remaining 23 objects, 22 are associated with active galactic nuclei or galaxies (including the five intra-hour variables that have been reported previously), and their variations are caused by discrete, local plasma screens. The remaining source has no multi-wavelength counterparts and is therefore yet to be identified. This is the first large-scale radio survey for variables and transient sources on minute timescales at a sub-mJy sensitivity level. We expect to discover $\sim$1 highly variable source per day using the same technique on the full ASKAP surveys.

Variable star

Pathfinder

Transient (computer programming)

Source counts

Millisecond

10.1093/mnras/stad1727

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Citations (6)

Discovery of H i gas in a young radio galaxy at z = 0.44 using the Australian Square Kilometre Array Pathfinder

Monthly Notices of the Royal Astronomical Society (2015)

J. R. Allison E. M. Sadler V. A. Moss M. T. Whiting R. W. Hunstead

We report the discovery of a new 21-cm HI absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.5 - 1015.5 MHz band of ASKAP we were able to conduct a blind search for the 21-cm line in a continuous redshift range between $z = 0.4$ and 1.0, which has, until now, remained largely unexplored. The absorption line is detected at $z = 0.44$ towards the GHz-peaked spectrum radio source PKS B1740$-$517 and demonstrates ASKAP's excellent capability for performing a future wide-field survey for HI absorption at these redshifts. Optical spectroscopy and imaging using the Gemini-South telescope indicates that the HI gas is intrinsic to the host galaxy of the radio source. The narrow OIII emission lines show clear double-peaked structure, indicating either large-scale outflow or rotation of the ionized gas. Archival data from the \emph{XMM-Newton} satellite exhibit an absorbed X-ray spectrum that is consistent with a high column density obscuring medium around the active galactic nucleus. The HI absorption profile is complex, with four distinct components ranging in width from 5 to 300 km s$^{-1}$ and fractional depths from 0.2 to 20 per cent. In addition to systemic HI gas, in a circumnuclear disc or ring structure aligned with the radio jet, we find evidence for a possible broad outflow of neutral gas moving at a radial velocity of $v \sim 300$ km s$^{-1}$. We infer that the expanding young radio source ($t_{\rm age} \approx 2500$ yr) is cocooned within a dense medium and may be driving circumnuclear neutral gas in an outflow of $\sim$ 1 $\mathrm{M}_{\odot}$ yr$^{-1}$.

Pathfinder

Outflow

Line (geometry)

10.1093/mnras/stv1532

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Citations (66)

A search for variable and transient radio sources in the extended Chandra Deep Field South at 5.5 GHz

Monthly Notices of the Royal Astronomical Society (2015)

M. E. Bell Minh Huynh P. J. Hancock Tara Murphy B. M. Gaensler

We present a three epoch survey for transient and variables in the extended Chandra Deep Field South at 5.5 GHz with the Australia Telescope Compact Array. A region covering $\sim$0.3 deg$^{2}$ was observed on timescales of 2.5 months and 2.5 years and typical sensitivities 12.1 $-$ 17.1 $\mu$Jy beam$^{-1}$ (1$\sigma$) were achieved. This survey represents the deepest search for transient and variable radio sources at 5.5 GHz. In total 124 sources were detected above the 5.5$\sigma$ level. One highly variable radio source was found with $\Delta S > 50%$ implying a surface density of $\sim$3 deg$^{-2}$. A further three radio sources were found with lower levels of variability equating to a surface density of $\sim$13 deg$^{-2}$ above a detection threshold of 82.3 $\mu$Jy. All of the variable sources have inverted radio spectra (between 1.4 and 5.5 GHz) and are associated with active galactic nuclei. We conclude that these variables are young gigahertz peaked-spectrum sources with active and self-absorbed radio jets. We explore the variability completeness of this sample and conclude that the fairly low levels of variability would only be detectable in 3$-$25% of all sources within the field. No radio transients were detected in this survey and we place an upper limit on the surface density of transient events $ < 7.5$ deg$^{-2}$ above a detection threshold of 68.8~$\mu$Jy.

Sigma

10.1093/mnras/stv882

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Citations (30)

The CRAFT coherent (CRACO) upgrade I: System description and results of the 110-ms radio transient pilot survey

Publications of the Astronomical Society of Australia (2025)

Ziteng Wang K. W. Bannister Vivek Gupta Xiao-Dong Deng M. A. Pilawa

Abstract We present the first results from a new backend on the Australian Square Kilometre Array Pathfinder, the Commensal Realtime ASKAP Fast Transient COherent (CRACO) upgrade. CRACO records millisecond time resolution visibility data, and searches for dispersed fast transient signals including fast radio bursts (FRB), pulsars, and ultra-long period objects (ULPO). With the visibility data, CRACO can localise the transient events to arcsecond-level precision after the detection. Here, we describe the CRACO system and report the result from a sky survey carried out by CRACO at 110-ms resolution during its commissioning phase. During the survey, CRACO detected two FRBs (including one discovered solely with CRACO, FRB 20231027A), reported more precise localisations for four pulsars, discovered two new RRATs, and detected one known ULPO, GPM J1839 $-$ 10, through its sub-pulse structure. We present a sensitivity calibration of CRACO, finding that it achieves the expected sensitivity of 11.6 Jy ms to bursts of 110 ms duration or less. CRACO is currently running at a 13.8 ms time resolution and aims at a 1.7 ms time resolution before the end of 2024. The planned CRACO has an expected sensitivity of 1.5 Jy ms to bursts of 1.7 ms duration or less and can detect $10\times$ more FRBs than the current CRAFT incoherent sum system (i.e. 0.5 $-$ 2 localised FRBs per day), enabling us to better constrain the models for FRBs and use them as cosmological probes.

Upgrade

Transient (computer programming)

Radio Astronomy

Craft

10.1017/pasa.2024.107

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Citations (0)

Data from the ASKAP latitude 50 Fast Radio Burst (FRB) sample

R. M. Shannon K. W. Bannister

Sample (material)

10.25919/5b6ae6b515850

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A search for long-time-scale, low-frequency radio transients

Monthly Notices of the Royal Astronomical Society (2016)

Tara Murphy D. L. Kaplan S. Croft C. Lynch J. R. Callingham

We present a search for transient and highly variable sources at low radio frequencies (150-200 MHz) that explores long timescales of 1-3 years. We conducted this search by comparing the TIFR GMRT Sky Survey Alternative Data Release 1 (TGSS ADR1) and the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey catalogues. To account for the different completeness thresholds in the individual surveys, we searched for compact GLEAM sources above a flux density limit of 100 mJy that were not present in the TGSS ADR1; and also for compact TGSS ADR1 sources above a flux density limit of 200 mJy that had no counterpart in GLEAM. From a total sample of 234 333 GLEAM sources and 275 612 TGSS ADR1 sources in the overlap region between the two surveys, there were 99658 GLEAM sources and 38 978 TGSS ADR sources that passed our flux density cutoff and compactness criteria. Analysis of these sources resulted in three candidate transient sources. Further analysis ruled out two candidates as imaging artefacts. We analyse the third candidate and show it is likely to be real, with a flux density of 182 +/- 26 mJy at 147.5 MHz. This gives a transient surface density of rho = (6.2 +/- 6) x 10-5 deg-2 . We present initial follow-up observations and discuss possible causes for this candidate. The small number of spurious sources from this search demonstrates the high reliability of these two new low-frequency radio catalogues.

Spurious relationship

Transient (computer programming)

10.1093/mnras/stw3087

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Citations (33)

A High-resolution View of Fast Radio Burst Host Environments

The Astrophysical Journal (2021)

Alexandra G. Mannings W. Fong Sunil Simha J. X. Prochaska Marc Rafelski

Abstract We present Hubble Space Telescope ultraviolet and infrared observations of eight fast radio burst (FRB) host galaxies with subarcsecond localizations, including the hosts of three known repeating FRBs. We quantify their spatial distributions and locations with respect to their host galaxy light distributions, finding that they occur at moderate host-normalized offsets of 1.4 r e ([0.6, 2.1] r e ; 68% interval) and on fainter regions of their hosts in terms of IR light but overall trace the radial distribution of IR light in their galaxies. The FRBs in our tested distribution do not clearly trace the distributions of any other transient population with known progenitors and are statistically distinct from the locations of LGRBs, H-poor SLSNe, SGRBs, and Ca-rich transients. We further find that most FRBs are not in regions of elevated local star formation rates and stellar mass surface densities in comparison to the mean global values of their hosts. We also place upper limits on the IR flux at the FRB positions of m IR ≳ 24.8–27.6 AB mag, constraining both satellite and background galaxies to luminosities well below the host luminosity of FRB 121102. We find that 5/8 FRB hosts exhibit clear spiral arm features in IR light, and that the positions of all well-localized FRBs located in such hosts are consistent with their spiral arms, although not on their brightest regions. Our results do not strongly support the primary progenitor channel of FRBs being connected with either the most massive (stripped-envelope) stars or events that require kicks and long delay times (neutron star mergers).

Spitzer Space Telescope

10.3847/1538-4357/abff56

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Citations (23)