A Southern-Hemisphere all-sky radio transient monitor for SKA-Low prototype stations

Sokołowski, M.; Wayth, R. B.; Price, Danny C.; Broderick, J. W.; Bernardi, G.; Bolli, Pietro; Chiello, Riccardo; Comoretto, G.; Crosse, B.; Davidson, David; Macario, G.; Magro, Alessio; Mattana, A.; Minchin, D.; McPhail, A.; Monari, Jader; Perini, Federico; Pupillo, G.; Sleap, G.; Tingay, S. J.; Ung, D.; Williams, Anne

doi:10.1017/pasa.2021.16

Cited by 18 publications

(19 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Early works include preliminary results on Sun and galaxy transit with a calibrated station, 2,20 sensitivity verification studies, 21 and an all-sky southern-hemisphere radio transient monitor. 22…”

Section: Skala41 Antenna and Aavsstationmentioning

confidence: 99%

Computational electromagnetics for the SKA-Low prototype station AAVS2

Bolli

Davidson

Bercigli

et al. 2022

J. Astron. Telesc. Instrum. Syst.

View full text Add to dashboard Cite

We summarize the activities conducted since 2019 in the numerical electromagnetic analysis of one prototype station of the SKA-Low telescope. Working closely with the SKA Observatory, two teams based in Australia and Italy have collaborated effectively in modeling and analyzing AAVS2, which is the most recent prototype of an SKA-Low station installed in Western Australia. A comprehensive overview of the main electromagnetic parameters at element and array level obtained with two different commercial solvers is presented. Results for scattering parameters, individual element patterns, and station beams are shown; all these fully incorporate mutual coupling effects. Sensitivity of the station is addressed, as the crosspolarization performance. Finally, we also address some lessons learned and their impact on the project.

show abstract

Section: Skala41 Antenna and Aavsstationmentioning

confidence: 99%

Computational electromagnetics for the SKA-Low prototype station AAVS2

Bolli

Davidson

Bercigli

et al. 2022

J. Astron. Telesc. Instrum. Syst.

View full text Add to dashboard Cite

show abstract

“…The low-frequency component of the Square Kilometre Array (SKA-Low; Dewdney et al 2009) is a radio telescope covering the frequency range 50-350 MHz and of an unprecedented sensitivity, resulting from the enormous number of dual-polarisation antennas (Sokolowski et al 2021). Given the model predictions shown in Section 4.3.3, the far greater sensitivity of the SKA-Low will rigorously test these models.…”

Section: Prospects For Ska-lowmentioning

confidence: 99%

“…Therefore, it is plausible to implement our rapid-response system on the SKA-Low to search for coherent radio emission associated with GRBs. A future plan to enhance the SKA-Low system with the triggering capability to react to external transient alerts has been proposed by Sokolowski et al (2021).…”

Section: Prospects For Ska-lowmentioning

confidence: 99%

Early-time searches for coherent radio emission from short GRBs with the Murchison Widefield Array

Tian

Anderson

Hancock

et al. 2022

Publ. Astron. Soc. Aust.

Self Cite

View full text Add to dashboard Cite

Many short gamma-ray bursts (GRBs) originate from binary neutron star mergers, and there are several theories that predict the production of coherent, prompt radio signals either prior, during, or shortly following the merger, as well as persistent pulsar-like emission from the spin-down of a magnetar remnant. Here we present a low frequency (170–200 MHz) search for coherent radio emission associated with nine short GRBs detected by the Swift and/or Fermi satellites using the Murchison Widefield Array (MWA) rapid-response observing mode. The MWA began observing these events within 30–60 s of their high-energy detection, enabling us to capture any dispersion delayed signals emitted by short GRBs for a typical range of redshifts. We conducted transient searches at the GRB positions on timescales of 5 s, 30 s, and 2 min, resulting in the most constraining flux density limits on any associated transient of 0.42, 0.29, and 0.084 Jy, respectively. We also searched for dispersed signals at a temporal and spectral resolution of 0.5 s and 1.28 MHz, but none were detected. However, the fluence limit of 80–100 Jy ms derived for GRB 190627A is the most stringent to date for a short GRB. Assuming the formation of a stable magnetar for this GRB, we compared the fluence and persistent emission limits to short GRB coherent emission models, placing constraints on key parameters including the radio emission efficiency of the nearly merged neutron stars ( $\epsilon_r\lesssim10^{-4}$ ), the fraction of magnetic energy in the GRB jet ( $\epsilon_B\lesssim2\times10^{-4}$ ), and the radio emission efficiency of the magnetar remnant ( $\epsilon_r\lesssim10^{-3}$ ). Comparing the limits derived for our full GRB sample (along with those in the literature) to the same emission models, we demonstrate that our fluence limits only place weak constraints on the prompt emission predicted from the interaction between the relativistic GRB jet and the interstellar medium for a subset of magnetar parameters. However, the 30-min flux density limits were sensitive enough to theoretically detect the persistent radio emission from magnetar remnants up to a redshift of $z\sim0.6$ . Our non-detection of this emission could imply that some GRBs in the sample were not genuinely short or did not result from a binary neutron star merger, the GRBs were at high redshifts, these mergers formed atypical magnetars, the radiation beams of the magnetar remnants were pointing away from Earth, or the majority did not form magnetars but rather collapse directly into black holes.

show abstract

“…Visibilities were generated from the complex voltages of individual antennas using a software correlator, 9,13 yielding 32 finer channels, each 28.935 kHz wide. They were stored using the UVFITS format.…”

Section: Observations and Data Processingmentioning

confidence: 99%

Characterization of the SKA1-Low prototype station Aperture Array Verification System 2

Macario

Pupillo

Bernardi

et al. 2022

J. Astron. Telesc. Instrum. Syst.

View full text Add to dashboard Cite

The low frequency component of the Square Kilometre Array (SKA1-Low) will be an aperture phased array located at the Murchison Radio-astronomy Observatory (MRO) site in Western Australia. It will be composed of 512 stations, each consisting of 256 log-periodic dual-polarized antennas, and will operate in the low frequency range (50 to 350 MHz) of the SKA bandwidth. The Aperture Array Verification System 2 (AAVS2), operational since late 2019, is the last full-size engineering prototype station deployed at the MRO site before the start of the SKA1-Low construction phase. The aim of this paper is to characterize the station performance through commissioning observations at six different frequencies (55, 70, 110, 160, 230, and 320 MHz) collected during its first year of activities. We describe the calibration procedure, present the resulting all-sky images and their analysis, and discuss the station calibratability and system stability. Using the difference imaging method, we also derive estimates of the SKA1-Low sensitivity for the same frequencies and compare them with those obtained through electromagnetic simulations across the entire telescope bandwidth, finding good agreement (within 13%). Moreover, our estimates exceed the SKA1-Low requirements at all considered frequencies by up to a factor of ∼2.3. Our results are very promising and allow for an initial validation of the AAVS2 prototype station performance, which is an important step toward the coming SKA1-Low telescope construction and science.

show abstract

A Southern-Hemisphere all-sky radio transient monitor for SKA-Low prototype stations

Cited by 18 publications

References 68 publications

Computational electromagnetics for the SKA-Low prototype station AAVS2

Computational electromagnetics for the SKA-Low prototype station AAVS2

Early-time searches for coherent radio emission from short GRBs with the Murchison Widefield Array

Characterization of the SKA1-Low prototype station Aperture Array Verification System 2

Contact Info

Product

Resources

About