Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization

Pindor, B.; Wyithe, J. Stuart B.; Mitchell, D. A.; Ord, S. M.; Wayth, R. B.; Greenhill, L. J.

doi:10.1071/as10023

Cited by 33 publications

(36 citation statements)

References 38 publications

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“…However, with various modifications, many of the standard deconvolution approaches can be used to accurately remove PSF sidelobes, and developments are being made on a number of complementary fronts, see for example Pindor et al (2011), Bernardi et al (2011), Williams et al (2012, I. Sullivan et al (2012), Mitchell et al (2012), and G. Bernardi et al (2012).…”

Section: Tingay Et Almentioning

confidence: 99%

The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies

Tingay

Goeke

Bowman

et al. 2013

Publ. Astron. Soc. Aust.

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1,135

637

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The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80-300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ß3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.

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Section: Tingay Et Almentioning

confidence: 99%

The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies

Tingay

Goeke

Bowman

et al. 2013

Publ. Astron. Soc. Aust.

Self Cite

1,135

637

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“…has been obtained, the remaining major challenge will be the separation of the EoR signal from the astrophysical foregrounds. Foreground removal is generally considered to be a three stage process: bright source removal (e.g., Di Matteo et al 2004;Pindor et al 2011;Bernardi et al 2011), spectral fitting (e.g., Shaver et al 1999;Santos et al 2005;Wang et al 2006;McQuinn et al 2006;Bowman et al 2006;Jelić et al 2008;Harker et al 2009aHarker et al , 2010Petrovic & Oh 2011;Trott et al 2012), and residual error subtraction (Morales & Hewitt 2004) though efforts have been made to merge these steps (Gleser et al 2008;Mao 2012;Petrovic & Oh 2011).…”

Section: Removalmentioning

confidence: 99%

Reionization and the Cosmic Dawn with the Square Kilometre Array

et al. 2013

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The Square Kilometre Array (SKA) will have a low frequency component (SKA-low) which has as one of its main science goals the study of the redshifted 21cm line from the earliest phases of star and galaxy formation in the Universe. This 21cm signal provides a new and unique window both on the time of the formation of the first stars and accreting black holes and the subsequent period of substantial ionization of the intergalactic medium. The signal will teach us fundamental new things about the earliest phases of structure formation, cosmology and even has the potential to lead to the discovery of new physical phenomena. Here we present a white paper with an Executive SummaryThe Square Kilometre Array (SKA) will have a low frequency component (AA-low/SKA-low 1 ) which has as one of its main science goals the study of the redshifted 21cm line from the earliest phases of star and galaxy formation in the Universe (see SKA Memo 125). It is during this phase that the first building blocks of the galaxies that we see around us today, including our own Milky Way, were formed. It is a crucial period for understanding the history of the Universe and one for which we have currently very little observational data.We divide the period into two different phases based on the physical processes which affect the Intergalactic Medium. The first period, which we call the Cosmic Dawn, saw the formation of the first stars and accreting black holes, which changed the quantum state of the still neutral Intergalactic Medium. The second period, known as the Epoch of Reionization, is the one during which large areas between the galaxies were photo-ionized by the radiation produced in galaxies and which ended when the Intergalactic Medium had become completely ionized.Observations of the redshifted 21-cm line with SKA will provide a new and unique window on the entire period of Cosmic Dawn and Reionization. The signal is sensitive to the emergence of the first stellar populations, radiation from growing massive black holes and the formation of larger groups of galaxies and bright quasars. At the same time it maps the distribution of most of the baryonic matter in the Universe. The study of the redshifted 21cm line will teach us fundamental new things about the earliest phases of structure formation and cosmology. It even has the potential to lead to the discovery of new physical phenomena. Here we present an overview of the science questions that SKA-low can address, how we plan to tackle these questions and what this implies for the basic design of the telescope.The redshifted 21cm signal will be analyzed with different techniques, which each come with their own requirements for the SKA: (i) Tomography, (ii) power-spectra and higher-order statistics, (iii) hydrogen absorption, (iv) global/total-intensity signal. Whereas all precursors/pathfinders aim to study the signal statistically through its power spectrum, SKA will be able to image the neutral hydrogen distribution directly and its focus will therefore be more on tomograph...

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“…In reality, there are many issues which make an accurate subtraction of point sources from radio interferometric wide-field synthesis images challenging. These include residual gain calibration errors (Datta et al, 2010), direction dependence of the calibration due to instrumental or ionospheric/atmospheric conditions (Intema et al, 2009;Yatawatta, 2012), the effect of spectral index of the sources (Rau & Cornwell, 2011), frequency dependence and asymmetry of the primary beam response, varying point spread function (synthesized beam) of the telescope (Liu et al, 2009a;Morales et al, 2012;Ghosh et al, 2012), high computational expenses of imaging a large field of view, and CLEANing a large number of point sources (particularly severe at low radio frequency images, Pindor et al, 2011) etc. Note that these issues are more prominent at low radio frequencies due to a comparatively large field of view as well as a large number of strong point sources and bright Galactic synchrotron emission.…”

Section: Discussionmentioning

confidence: 99%

Validating a novel angular power spectrum estimator using simulated low frequency radio-interferometric data

et al. 2017

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The "Tapered Gridded Estimator" (TGE) is a novel way to directly estimate the angular power spectrum from radio-interferometric visibility data that reduces the computation by efficiently gridding the data, consistently removes the noise bias, and suppresses the foreground contamination to a large extent by tapering the primary beam response through an appropriate convolution in the visibility domain. Here we demonstrate the effectiveness of TGE in recovering the diffuse emission power spectrum through numerical simulations. We present details of the simulation used to generate low frequency visibility data for sky model with extragalactic compact radio sources and diffuse Galactic synchrotron emission. We then use different imaging strategies to identify the most effective option of point source subtraction and to study the underlying diffuse emission. Finally, we apply TGE to the residual data to measure the angular power spectrum, and assess the impact of incomplete point source subtraction in recovering the input power spectrum C ℓ of the synchrotron emission. This estimator is found to successfully recovers the C ℓ of input model from the residual visibility data. These results are relevant for measuring the diffuse emission like the Galactic synchrotron emission. It is also an important step towards characterizing and removing both diffuse and compact foreground emission in order to detect the redshifted 21 cm signal from the Epoch of Reionization.

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Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization

Cited by 33 publications

References 38 publications

The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies

The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies

Reionization and the Cosmic Dawn with the Square Kilometre Array

Validating a novel angular power spectrum estimator using simulated low frequency radio-interferometric data

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