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The low-frequency polarisation properties of radio sources are poorly studied, particularly in statistical samples. However, the new generation of low-frequency telescopes, such as the Murchison Widefield Array (MWA; the precursor for the…

We performed GMRT low frequency observations of the radio halos, relics and new candidates belonging to the GMRT Radio Halo Cluster Sample first observed at 610 MHz. High sensitivity imaging was performed using the GMRT at 325 MHz and 240…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Tiziana Venturi , Simona Giacintucci , Daniele Dallacasa , Rossella Cassano , Gianfranco Brunetti , Giulia Macario , Ramana Athreya

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 of them…

We provide the first in situ measurements of antenna element (tile) beam shapes of the Murchison Widefield Array (MWA), a low radio-frequency interferometer and an SKA precursor. Most current MWA processing pipelines use an assumed beam…

Radio relics, arc-like polarized sources with highly aligned magnetic fields, are typically found on the outskirts of merging galaxy clusters. The magneto-ionic media responsible for the significant coherence observed in radio relics remain…

High Energy Astrophysical Phenomena · Physics 2025-08-28 Arpan Pal , Ruta Kale , Reinout J. van Weeren

We report on the detection of source noise in the time domain at 162MHz with the Murchison Widefield Array. During the observation the flux of our target source Virgo A (M87) contributes only $\sim$1\% to the total power detected by any…

Instrumentation and Methods for Astrophysics · Physics 2021-04-14 John Morgan , Ron Ekers

We present a numerical model for the extended steep-spectrum radio sources and the elongated X-ray structure in A3667 based on new 3-dimensional MHD/N-body simulations. The X-ray and optical analyses of A3667 indicate that it has undergone…

Astrophysics · Physics 2009-10-31 K. Roettiger , J. O. Burns , J. M. Stone

We describe the motivation and design details of the "Phase II" upgrade of the Murchison Widefield Array (MWA) radio telescope. The expansion doubles to 256 the number of antenna tiles deployed in the array. The new antenna tiles enhance…

Accurate antenna beam models are critical for radio observations aiming to isolate the redshifted 21cm spectral line emission from the Dark Ages and the Epoch of Reionization and unlock the scientific potential of 21cm cosmology. Past work…

We have detected a radio bridge of unpolarized synchrotron emission connecting the NW relic of the galaxy cluster Abell 3667 to its central regions. We used data at 2.3 GHz from the S-band Polarization All Sky Survey (S-PASS) and at 3.3 GHz…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 E. Carretti , S. Brown , L. Staveley-Smith , J. M. Malarecki , G. Bernardi , B. M. Gaensler , M. Haverkorn , M. J. Kesteven , S. Poppi

We present the second data release for the GaLactic and Extragalactic All-sky Murchison Widefield Array eXtended (GLEAM-X) survey. This data release is an area of 12,892-deg^2 around the South Galactic Pole region covering 20h 40m <= RA <=…

Polarimetric studies of pulsars at low radio frequencies provide important observational insights into the pulsar emission mechanism and beam models, and probe the properties of the magneto-ionic interstellar medium (ISM). Aperture arrays…

High Energy Astrophysical Phenomena · Physics 2019-08-07 Mengyao Xue , S. M. Ord , S. E. Tremblay , N. D. R. Bhat , C. Sobey , B. W. Meyers , S. J. McSweeney , N. A. Swainston

We present evidence for the existence of significant substructure in the cold front cluster Abell 3667 based on multi-object spectroscopy taken with the 3.9m Anglo Australian Telescope. This paper is the second in a series analyzing the…

Astrophysics · Physics 2011-02-11 Matt S. Owers , Warrick J. Couch , Paul E. J. Nulsen

Deep imaging of structures from the Cosmic Dawn (CD) and the Epoch of Reionization (EoR) in five targeted fields is one of the highest priority scientific objectives for the Square Kilometre Array (SKA). Selecting 'quiet' fields, which…

Instrumentation and Methods for Astrophysics · Physics 2025-07-14 Xueying Zhang , Qian Zheng , Linhui Wu , Quan Guo , Stefan W. Duchesne , Mengfan He , Huanyuan Shan , Xiang-ping Wu , Melanie Johnston-Hollitt , Feiyu Zhao , Qingyuan Ma

The radio interferometric closure phases can be a valuable tool for studying cosmological {H\scriptsize{I}}~from the early Universe. Closure phases have the advantage of being immune to element-based gains and associated calibration errors.…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-05 Himanshu Tiwari , Nithyanandan Thyagarajan , Cathryn M. Trott , Benjamin McKinley

(abridged) Radio recombination lines (RRLs) at frequencies $\nu$ < 250 MHz trace the cold, diffuse phase of the ISM. Next generation low frequency interferometers, such as LOFAR, MWA and the future SKA, with unprecedented sensitivity,…

Instrumentation and Methods for Astrophysics · Physics 2020-02-26 K. L. Emig , P. Salas , F. de Gasperin , J. B. R. Oonk , M. C. Toribio , A. P. Mechev , H. J. A. Rottgering , A. G. G. M. Tielens

We present a multi-wavelength analysis of the merging rich cluster of galaxies Abell 2256. We have observed A2256 at 150 MHz using the Giant Metrewave Radio Telescope and successfully detected the diffuse radio halo and the relic emission…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Kale Ruta , K. S. Dwarakanath

We present a study of the radio properties of 870$\mu$m-selected submillimetre galaxies (SMGs), observed at high resolution with ALMA in the Extended Chandra Deep Field South. From our initial sample of 76 ALMA SMGs, we detect 52 SMGs at…