The Australia Telescope Compact Array Broad-band Backend: description and first results★

Wilson, W. E.; Ferris, R. H.; Axtens, P.; Brown, Andrew; Davis, E. G.; Hampson, G.A.; Leach, M.; Roberts, P.; Saunders, S.; Koribalski, B. S.; Caswell, J. L.; Lenc, E.; Stevens, J.; Voronkov, Maxim; Wieringa, M.; Brooks, Kate; Edwards, P. G.; Ekers, R. D.; Emonts, Bjorn; Hindson, L.; Johnston, S.; Maddison, Sarah; Mahony, E. K.; Malu, Siddharth; Massardi, M.; Mao, Minnie; McConnell, D.; Norris, R. P.; Schnitzeler, Dominic; Subrahmanyan, R.; Urquhart, J. S.; Thompson, Michelle; Wark, R. M.

doi:10.1111/j.1365-2966.2011.19054.x

Cited by 354 publications

(187 citation statements)

References 87 publications

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“…The Compact Array Broadband Backend (CABB, Wilson et al 2011) provides two IF bands, each of 2 GHz bandwidth. In the CFB 64M-32k mode adopted for these observations, each 2 GHz band was divided into 32×64 MHz "continuum" channels with 16 "zoombands" of 2048×32 kHz channels selected in each IF band for spectral line observations.…”

Section: Observationsmentioning

confidence: 99%

The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone

Krieger

Ott

Beuther

et al. 2017

ApJ

117

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The Survey of Water and Ammonia in the Galactic Center (SWAG) covers the Central Molecular Zone (CMZ) of the Milky Way at frequencies between 21.2 and 25.4 GHz obtained at the Australia Telescope Compact Array at ∼0.9 pc spatial and ∼2.0 km s −1 spectral resolution. In this paper, we present data on the inner ∼250 pc (1°.4) between SgrC and SgrB2. We focus on the hyperfine structure of the metastable ammonia inversion lines (J, K )=(1, 1)-(6, 6) to derive column density, kinematics, opacity, and kinetic gas temperature. In the CMZ molecular clouds, we find typical line widths of 8-16 km s −1 and extended regions of optically thick (τ>1) emission. Two components in kinetic temperature are detected at 25-50 K and 60-100 K, both being significantly hotter than the dust temperatures throughout the CMZ. We discuss the physical state of the CMZ gas as traced by ammonia in the context of the orbital model by Kruijssen et al. that interprets the observed distribution as a stream of molecular clouds following an open eccentric orbit. This allows us to statistically investigate the time dependencies of gas temperature, column density, and line width. We find heating rates between ∼50 and ∼100 K Myr −1 along the stream orbit. No strong signs of time dependence are found for column density or line width. These quantities are likely dominated by cloud-to-cloud variations. Our results qualitatively match the predictions of the current model of tidal triggering of cloud collapse, orbital kinematics, and the observation of an evolutionary sequence of increasing star formation activity with orbital phase.

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Section: Observationsmentioning

confidence: 99%

The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone

Krieger

Ott

Beuther

et al. 2017

ApJ

117

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“…The observation parameters are listed in Table 1. All of the observations were carried out prior to the Compact Array Broadband Backend (CABB) upgrade (Wilson et al 2011). The data were taken in continuum mode with all four Stokes parameters recorded over a usable bandwidth of 104 MHz at each frequency.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Radio Polarization Observations of the Snail: A Crushed Pulsar Wind Nebula in G327.1–1.1 With a Highly Ordered Magnetic Field

Bucciantini

et al. 2016

ApJ

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Pulsar wind nebulae (PWNe) are suggested to be acceleration sites of cosmic rays in the Galaxy. While the magnetic field plays an important role in the acceleration process, previous observations of magnetic field configurations of PWNe are rare, particularly for evolved systems. We present a radio polarization study of the "Snail" PWN inside the supernova remnant G327.1−1.1 using the Australia Telescope Compact Array. This PWN is believed to have been recently crushed by the supernova (SN) reverse shock. The radio morphology is composed of a main circular body with a finger-like protrusion. We detected a strong linear polarization signal from the emission, which reflects a highly ordered magnetic field in the PWN and is in contrast to the turbulent environment with a tangled magnetic field generally expected from hydrodynamical simulations. This could suggest that the characteristic turbulence scale is larger than the radio beam size. We built a toy model to explore this possibility, and found that a simulated PWN with a turbulence scale of about one-eighth to one-sixth of the nebula radius and a pulsar wind filling factor of 50%-75% provides the best match to observations. This implies substantial mixing between the SN ejecta and pulsar wind material in this system.

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“…We observed the 40 sample sources using the Australia Telescope Compact Array (ATCA; Wilson et al 2011) over 1.1-3.1 GHz, 4.5-6.5 GHz, and 8.0-10.0 GHz in full polarization with a nominal 1 MHz channel resolution. At each end of each of these bands, 100 channels were flagged due to diminished sensitivity in these regions, resulting in an effective frequency coverage of 1.2-3.0 GHz, 4.6-6.4 GHz, and 8.1-9.9 GHz.…”

Section: Observations and Calibrationmentioning

confidence: 99%

A STUDY OF BROADBAND FARADAY ROTATION AND POLARIZATION BEHAVIOR OVER 1.3–10 GHz IN 36 DISCRETE RADIO SOURCES

Anderson

Gaensler

Feain

2016

ApJ

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We present a broadband polarization analysis of 36 discrete polarized radio sources over a very broad, densely sampled frequency band. Our sample was selected on the basis of polarization behavior apparent in narrowband archival data at 1.4 GHz: half the sample shows complicated frequency-dependent polarization behavior (i.e., Faraday complexity) at these frequencies, while half shows comparatively simple behavior (i.e., they appear Faraday simple). We re-observed the sample using the Australia Telescope Compact Array in full polarization, with 6 GHz of densely sampled frequency coverage spanning 1.3-10 GHz. We have devised a general polarization modeling technique that allows us to identify multiple polarized emission components in a source, and to characterize their properties. We detect Faraday complex behavior in almost every source in our sample. Several sources exhibit particularly remarkable polarization behavior. By comparing our new and archival data, we have identified temporal variability in the broadband integrated polarization spectra of some sources. In a number of cases, the characteristics of the polarized emission components, including the range of Faraday depths over which they emit, their temporal variability, spectral index, and the linear extent of the source, allow us to argue that the spectropolarimetric data encode information about the magneto-ionic environment of active galactic nuclei themselves. Furthermore, the data place direct constraints on the geometry and magneto-ionic structure of this material. We discuss the consequences of restricted frequency bands on the detection and interpretation of polarization structures, and the implications for upcoming spectropolarimetric surveys.

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The Australia Telescope Compact Array Broad-band Backend: description and first results★

Cited by 354 publications

References 87 publications

The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone

The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone

Radio Polarization Observations of the Snail: A Crushed Pulsar Wind Nebula in G327.1–1.1 With a Highly Ordered Magnetic Field

A STUDY OF BROADBAND FARADAY ROTATION AND POLARIZATION BEHAVIOR OVER 1.3–10 GHz IN 36 DISCRETE RADIO SOURCES

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