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1. GASKAP-HI Pilot Survey Science I: ASKAP Zoom Observations of HI Emission in the Small Magellanic Cloud

Author

Pingel, N. M., Dempsey, J., McClure-Griffiths, N. M., Dickey, J. M., Jameson, K. E., Arce, H., Anglada, G., Bland-Hawthorn, J., Breen, S. L., Buckland-Willis, F., Clark, S. E., Dawson, J. R., Dénes, H., Di Teodoro, E. M., For, B. -Q., Foster, Tyler J., Gómez, J. F., Imai, H., Joncas, G., Kim, C. -G., Lee, M. -Y., Lynn, C., Leahy, D., Ma, Y. K., Marchal, A., McConnell, D., Miville-Deschênes, M. -A., Moss, V. A., Murray, C. E., Nidever, D., Peek, J., Stanimirović, S., Staveley-Smith, L., Tepper-Garcia, T., Tremblay, C. D., Uscanga, L., van Loon, J. Th., Vázquez-Semadeni, E., Allison, J. R., Anderson, C. S., Ball, Lewis, Bell, M., Bock, D. C. -J., Bunton, J., Cooray, F. R., Cornwell, T., Koribalski, B. S., Gupta, N., Hayman, D. B., Harvey-Smith, L., Lee-Waddell, K., Ng, A., Phillips, C. J., Voronkov, M., Westmeier, T., and Whiting, M. T.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present the most sensitive and detailed view of the neutral hydrogen (HI) emission associated with the Small Magellanic Cloud (SMC), through the combination of data from the Australian Square Kilometre Array Pathfinder (ASKAP) and Parkes (Murriyang), as part of the Galactic Australian Square Kilometre Array Pathfinder (GASKAP) pilot survey. These GASKAP-HI pilot observations, for the first time, reveal HI in the SMC on similar physical scales as other important tracers of the interstellar medium, such as molecular gas and dust. The resultant image cube possesses an rms noise level of 1.1 K (1.6 mJy/beam) per 0.98 km s$^{-1}$ spectral channel with an angular resolution of 30$''$ ($\sim$10 pc). We discuss the calibration scheme and the custom imaging pipeline that utilizes a joint deconvolution approach, efficiently distributed across a computing cluster, to accurately recover the emission extending across the entire $\sim$25 deg$^2$ field-of-view. We provide an overview of the data products and characterize several aspects including the noise properties as a function of angular resolution and the represented spatial scales by deriving the global transfer function over the full spectral range. A preliminary spatial power spectrum analysis on individual spectral channels reveals that the power-law nature of the density distribution extends down to scales of 10 pc. We highlight the scientific potential of these data by comparing the properties of an outflowing high velocity cloud with previous ASKAP+Parkes HI test observations., Comment: Accepted for publication in PASA, 34 pages, 18 figures, 5 tables

Published
2021
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2. Australian Square Kilometre Array Pathfinder: I. System Description

Author

Hotan, A. W., Bunton, J. D., Chippendale, A. P., Whiting, M., Tuthill, J., Moss, V. A., McConnell, D., Amy, S. W., Huynh, M. T., Allison, J. R., Anderson, C. S., Bannister, K. W., Bastholm, E., Beresford, R., Bock, D. C. -J., Bolton, R., Chapman, J. M., Chow, K., Collier, J. D., Cooray, F. R., Cornwell, T. J., Diamond, P. J., Edwards, P. G., Feain, I. J., Franzen, T. M. O., George, D., Gupta, N., Hampson, G. A., Harvey-Smith, L., Hayman, D. B., Heywood, I., Jacka, C., Jackson, C. A., Jackson, S., Jeganathan, K., Johnston, S., Kesteven, M., Kleiner, D., Koribalski, B. S., Lee-Waddell, K., Lenc, E., Lensson, E. S., Mackay, S., Mahony, E. K., McClure-Griffiths, N. M., McConigley, R., Mirtschin, P., Ng, A. K., Norris, R. P., Pearce, S. E., Phillips, C., Pilawa, M. A., Raja, W., Reynolds, J. E., Roberts, P., Roxby, D. N., Sadler, E. M., Shields, M., Schinckel, A. E. T., Serra, P., Shaw, R. D., Sweetnam, T., Troup, E. R., Tzioumis, A., Voronkov, M. A., and Westmeier, T.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

In this paper we describe the system design and capabilities of the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope at the conclusion of its construction project and commencement of science operations. ASKAP is one of the first radio telescopes to deploy phased array feed (PAF) technology on a large scale, giving it an instantaneous field of view that covers 31 square degrees at 800 MHz. As a two-dimensional array of 36x12m antennas, with baselines ranging from 22m to 6km, ASKAP also has excellent snapshot imaging capability and 10 arcsecond resolution. This, combined with 288 MHz of instantaneous bandwidth and a unique third axis of rotation on each antenna, gives ASKAP the capability to create high dynamic range images of large sky areas very quickly. It is an excellent telescope for surveys between 700 MHz and 1800 MHz and is expected to facilitate great advances in our understanding of galaxy formation, cosmology and radio transients while opening new parameter space for discovery of the unknown., Comment: 38 pages, 24 figures, accepted for publication in PASA

Published
2021
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3. Early Science from POSSUM: Shocks, turbulence, and a massive new reservoir of ionised gas in the Fornax cluster

Author

Anderson, C. S., Heald, G. H., Eilek, J. A., Lenc, E., Gaensler, B. M., Rudnick, Lawrence, Van Eck, C. L., O'Sullivan, S. P., Stil, J. M., Chippendale, A., Riseley, C. J., Carretti, E., West, J., Farnes, J., Harvey-Smith, L., McClure-Griffiths, N. M., Bock, Douglas C. J., Bunton, J. D., Koribalski, B., Tremblay, C. D., Voronkov, M. A., and Warhurst, K.

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the first Faraday rotation measure (RM) grid study of an individual low-mass cluster -- the Fornax cluster -- which is presently undergoing a series of mergers. Exploiting commissioning data for the POlarisation Sky Survey of the Universe's Magnetism (POSSUM) covering a $\sim34$ square degree sky area using the Australian Square Kilometre Array Pathfinder (ASKAP), we achieve an RM grid density of $\sim25$ RMs per square degree from a 280 MHz band centred at 887 MHz, which is similar to expectations for forthcoming GHz-frequency all-sky surveys. We thereby probe the extended magnetoionic structure of the cluster in unprecedented detail. We find that the scatter in the Faraday RM of confirmed background sources is increased by $16.8\pm2.4$ rad m$^{-2}$ within 1 degree (360 kpc) projected distance to the cluster centre, which is 2--4 times more extended than the presently-detectable X-ray-emitting intracluster medium (ICM). The Faraday-active plasma is more massive than the X-ray-emitting ICM, with an average density that broadly matches expectations for the Warm-Hot Intergalactic Medium. The morphology of the Faraday depth enhancement exhibits the classic morphology of an astrophysical bow shock on the southwest side of the main Fornax cluster, and an extended, swept-back wake on the northeastern side. Our favoured explanation is an ongoing merger between the main cluster and a sub-cluster to the southwest. The shock's Mach angle and stand-off distance lead to a self-consistent transonic merger speed with Mach 1.06. The region hosting the Faraday depth enhancement shows a decrement in both total and polarised intensity. We fail to identify a satisfactory explanation for this; further observations are warranted. Generally, our study illustrates the scientific returns that can be expected from all-sky grids of discrete sources generated by forthcoming all-sky radio surveys., Comment: Accepted for publication in PASA. 27 pages, 14 figures, 1 table

Published
2021
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4. Field sources near the southern-sky calibrator PKS B1934-638: effect on spectral line observations with SKA-MID and its precursors

Author

Heywood, I., Lenc, E., Serra, P., Hugo, B., Bannister, K. W., Bell, M. E., Chippendale, A., Harvey-Smith, L., Marvil, J., McConnell, D., and Voronkov, M. A.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Accurate instrumental bandpass corrections are essential for the reliable interpretation of spectral lines from targeted and survey-mode observations with radio interferometers. Bandpass correction is typically performed by comparing measurements of a strong calibrator source to an assumed model, typically an isolated point source. The wide field-of-view and high sensitivity of modern interferometers means that additional sources are often detected in observations of calibrators. This can introduce errors into bandpass corrections and subsequently the target data if not properly accounted for. Focusing on the standard calibrator PKS B1934-638, we perform simulations to asses this effect by constructing a wide-field sky model. The cases of ASKAP (0.7-1.9 GHz), MeerKAT (UHF: 0.58-1.05 GHz; L-band: 0.87-1.67 GHz) and Band 2 (0.95-1.76 GHz) of SKA-MID are examined. The use of a central point source model during bandpass calibration is found to impart amplitude errors into spectra measured by the precursor instruments at the ~0.2-0.5% level dropping to ~0.01% in the case of SKA-MID. This manifests itself as ripples in the source spectrum, the behaviour of which is coupled to the distribution of the array baselines, the solution interval, the primary beam size, the hour-angle of the calibration scan, as well as the weights used when imaging the target. Calibration pipelines should routinely employ complete field models for standard calibrators to remove this potentially destructive contaminant from the data, a recommendation we validate by comparing our simulation results to a MeerKAT scan of PKS B1934-638, calibrated with and without our expanded sky model., Comment: 11 pages, 10 figures, accepted for publication in MNRAS

Published
2020
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5. MAGMO: Polarimetry of 1720-MHz OH Masers towards Southern Star Forming Regions

Author

Ogbodo, C. S., Green, J. A., Dawson, J. R., Breen, S. L., Mao, S. A., McClure-Griffiths, N. M., Robishaw, T., and Harvey-Smith, L.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

From targeted observations of ground-state OH masers towards 702 Multibeam (MMB) survey 6.7-GHz methanol masers, between Galactic longitudes 186$^{\circ}$ through the Galactic centre to 20$^{\circ}$, made as part of the `MAGMO' project, we present the physical and polarisation properties of the 1720-MHz OH maser transition, including the identification of Zeeman pairs. We present 10 new and 23 previously catalogued 1720-MHz OH maser sources detected towards star formation regions. In addition, we also detected 16 1720-MHz OH masers associated with supernova remnants and two sites of diffuse OH emission. Towards the 33 star formation masers, we identify 44 Zeeman pairs, implying magnetic field strengths ranging from $-$11.4 to $+$13.2 mG, and a median magnetic field strength of $|B_{LOS}|$ $\sim$ 6 mG. With limited statistics, we present the in-situ magnetic field orientation of the masers and the Galactic magnetic field distribution revealed by the 1720-MHz transition. We also examine the association statistics of 1720-MHz OH SFR masers with other ground-state OH masers, excited-state OH masers, class I and class II methanol masers and water masers, and compare maser positions with mid-infrared images of the parent star forming regions. Of the 33 1720-MHz star formation masers, ten are offset from their central exciting sources, and appear to be associated with outflow activity.

Published
2020
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6. ASKAP Commissioning Observations of the GAMA 23 Field

Author

Leahy, Denis A., Hopkins, A. M., Norris, R. P., Marvil, J., Collier, J. D., Taylor, E. N., Allison, J. R., Anderson, C., Bell, M., Bilicki, M., Bland-Hawthorn, J., Brough, S., Brown, M. J. I., Driver, S., Gurkan, G., Harvey-Smith, L., Heywood, I., Holwerda, B. W., Liske, J., Lopez-Sanchez, A. R., McConnell, D., Moffett, A., Owers, M. S., Pimbblet, K. A., Raja, W., Seymour, N., Voronkov, M. A., and Wang, L.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We have observed the G23 field of the Galaxy And Mass Assembly (GAMA) survey using the Australian Square Kilometre Array Pathfinder (ASKAP) in its commissioning phase, to validate the performance of the telescope and to characterize the detected galaxy populations. This observation covers $\sim$48 deg$^2$ with synthesized beam of 32.7$^{\prime\prime}$ by 17.8$^{\prime\prime}$ at 936 MHz, and $\sim$39 deg$^2$ with synthesized beam of 15.8$^{\prime\prime}$ by 12.0$^{\prime\prime}$ at 1320 MHz. At both frequencies, the r.m.s. (root-mean-square) noise is $\sim$0.1 mJy/beam. We combine these radio observations with the GAMA galaxy data, which includes spectroscopy of galaxies that are i-band selected with a magnitude limit of 19.2. Wide-field Infrared Survey Explorer (WISE) infrared (IR) photometry is used to determine which galaxies host an active galactic nucleus (AGN). In properties including source counts, mass distributions, and IR vs. radio luminosity relation, the ASKAP detected radio sources behave as expected. Radio galaxies have higher stellar mass and luminosity in IR, optical and UV than other galaxies. We apply optical and IR AGN diagnostics and find that they disagree for $\sim$30% of the galaxies in our sample. We suggest possible causes for the disagreement. Some cases can be explained by optical extinction of the AGN, but for more than half of the cases we do not find a clear explanation. Radio sources are more likely ($\sim$6%) to have an AGN than radio quiet galaxies ($\sim$1%), but the majority of AGN are not detected in radio at this sensitivity., Comment: 26 pages, 22 figures, 6 tables. Accepted for publication in Publications of the Astronomical Society of Australia

Published
2019
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7. SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution - Survey Description and Compact Source Catalogue

Author

Eden, D. J., Liu, Tie, Kim, Kee-Tae, Liu, S. -Y., Tatematsu, K., Di Francesco, J., Wang, K., Wu, Y., Thompson, M. A., Fuller, G. A., Li, Di, Ristorcelli, I., Kang, Sung-ju, Hirano, N., Johnstone, D., Lin, Y., He, J. H., Koch, P. M., Sanhueza, Patricio, Qin, S. -L., Zhang, Q., Goldsmith, P. F., Evans II, N. J., Yuan, J., Zhang, C. -P., White, G. J., Choi, Minho, Lee, Chang Won, Toth, L. V., Mairs, S., Yi, H. -W., Tang, M., Soam, A., Peretto, N., Samal, M. R., Fich, M., Parsons, H., Malinen, J., Bendo, G. J., Rivera-Ingraham, A., Liu, H. -L., Wouterloot, J., Li, P. S., Qian, L., Rawlings, J., Rawlings, M. G., Feng, S., Wang, B., Li, Dalei, Liu, M., Luo, G., Marston, A. P., Pattle, K. M., Pelkonen, V. -M., Rigby, A. J., Zahorecz, S., Zhang, G., Bogner, R., Aikawa, Y., Akhter, S., Alina, D., Bell, G., Bernard, J. -P., Blain, A., Bronfman, L., Byun, D. -Y., Chapman, S., Chen, H. -R., Chen, M., Chen, W. -P., Chen, X., Chen, Xuepeng, Chrysostomou, A., Chu, Y. -H., Chung, E. J., Cornu, D., Cosentino, G., Cunningham, M. R., Demyk, K., Drabek-Maunder, E., Doi, Y., Eswaraiah, C., Falgarone, E., Feher, O., Fraser, H., Friberg, P., Garay, G., Ge, J. X., Gear, W. K., Greaves, J., Guan, X., Harvey-Smith, L., Hasegawa, T., He, Y., Henkel, C., Hirota, T., Holland, W., Hughes, A., Jarken, E., Ji, T. -G., Jimenez-Serra, I., Kang, Miju, Kawabata, K. S., Kim, Gwanjeong, Kim, Jungha, Kim, Jongsoo, Kim, S., Koo, B. -C., Kwon, Woojin, Kuan, Y. -J., Lacaille, K. M., Lai, S. -P., Lee, C. F., Lee, J. E., Lee, Y. -U., Li, H., Lo, N., Lopez, J. A. P., Lu, X., Lyo, A. -R., Mardones, D., McGehee, P., Meng, F., Montier, L., Montillaud, J., Moore, T. J. T., Morata, O., Moriarty-Schieven, G. H., Ohashi, S., Pak, S., Park, Geumsook, Paladini, R., Pech, G., Qiu, K., Ren, Z. -Y., Richer, J., Sakai, T., Shang, H., Shinnaga, H., Stamatellos, D., Tang, Y. -W., Traficante, A., Vastel, C., Viti, S., Walsh, A., Wang, H., Wang, J., Ward-Thompson, D., Whitworth, A., Wilson, C. D., Xu, Y., Yang, J., Yuan, Y. -L., Yuan, L., Zavagno, A., Zhang, C., Zhang, H. -W., Zhou, C., Zhu, J. Zhou. L., and Zuo, P.

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics
Abstract

We present the first release of the data and compact-source catalogue for the JCMT Large Program SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE). SCOPE consists of 850-um continuum observations of 1235 Planck Galactic Cold Clumps (PGCCs) made with the Submillimetre Common-User Bolometer Array 2 on the James Clerk Maxwell Telescope. These data are at an angular resolution of 14.4 arcsec, significantly improving upon the 353-GHz resolution of Planck at 5 arcmin, and allowing for a catalogue of 3528 compact sources in 558 PGCCs. We find that the detected PGCCs have significant sub-structure, with 61 per cent of detected PGCCs having 3 or more compact sources, with filamentary structure also prevalent within the sample. A detection rate of 45 per cent is found across the survey, which is 95 per cent complete to Planck column densities of $N_{H_{2}}$ $>$ 5 $\times$ 10$^{21}$ cm$^{-2}$. By positionally associating the SCOPE compact sources with YSOs, the star formation efficiency, as measured by the ratio of luminosity to mass, in nearby clouds is found to be similar to that in the more distant Galactic Plane, with the column density distributions also indistinguishable from each other., Comment: 16 pages, 13 figures, 1 table. Accepted for publication in MNRAS

Published
2019
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8. Connecting X-ray absorption and 21cm neutral hydrogen absorption in obscured radio AGN

Author

Moss, V. A., Allison, J. R., Sadler, E. M., Urquhart, R., Soria, R., Callingham, J. R., Curran, S. J., Musaeva, A., Mahony, E. K., Glowacki, M., Farrell, S. A., Bannister, K. W., Chippendale, A. P., Edwards, P. G., Harvey-Smith, L., Heywood, I., Hotan, A. W., Indermuehle, B. T., Lenc, E., Marvil, J., McConnell, D., Reynolds, J. E., Voronkov, M. A., Wark, R. M., and Whiting, M. T.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Many radio galaxies show the presence of dense and dusty gas near the active nucleus. This can be traced by both 21cm HI absorption and soft X-ray absorption, offering new insight into the physical nature of the circumnuclear medium of these distant galaxies. To better understand this relationship, we investigate soft X-ray absorption as an indicator for the detection of associated HI absorption, as part of preparation for the First Large Absorption Survey in HI (FLASH) to be undertaken with the Australian Square Kilometre Array Pathfinder (ASKAP). We present the results of our pilot study using the Boolardy Engineering Test Array, a precursor to ASKAP, to search for new absorption detections in radio sources brighter than 1 Jy that also feature soft X-ray absorption. Based on this pilot survey, we detected HI absorption towards the radio source PKS 1657-298 at a redshift of z = 0.42. This source also features the highest X-ray absorption ratio of our pilot sample by a factor of 3, which is consistent with our general findings that X-ray absorption predicates the presence of dense neutral gas. By comparing the X-ray properties of AGN with and without detection of HI absorption at radio wavelengths, we find that X-ray hardness ratio and HI absorption optical depth are correlated at a statistical significance of 4.71{\sigma}. We conclude by considering the impact of these findings on future radio and X-ray absorption studies., Comment: 22 pages, 20 figures, accepted for publication in MNRAS

Published
2017
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9. H2O Southern Galactic Plane Survey (HOPS): Paper III - Properties of Dense Molecular Gas across the Inner Milky Way

Author

Longmore, S. N., Walsh, A. J., Purcell, C. R., Burke, D. J., Henshaw, J., Walker, D., Urquhart, J., Barnes, A. T., Whiting, M., Burton, M. G., Breen, S. L., Britton, T., Brooks, K. J., Cunningham, M. R., Green, J. A., Harvey-Smith, L., Hindson, L., Hoare, M. G., Indermuehle, B., Jones, P. A., Lo, N., Lowe, V., Moore, T. J. T., Thompson, M. A., and Voronkov, M. A.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

The H2O Southern Galactic Plane Survey (HOPS) has mapped 100 square degrees of the Galactic plane for water masers and thermal molecular line emission using the 22-m Mopra telescope. We describe the automated spectral-line fitting pipelines used to determine the properties of emission detected in HOPS datacubes, and use these to derive the physical and kinematic properties of gas in the survey. A combination of the angular resolution, sensitivity, velocity resolution and high critical density of lines targeted make the HOPS data cubes ideally suited to finding precursor clouds to the most massive and dense stellar clusters in the Galaxy. We compile a list of the most massive HOPS ammonia regions and investigate whether any may be young massive cluster progenitor gas clouds. HOPS is also ideally suited to trace the flows of dense gas in the Galactic Centre. We find the kinematic structure of gas within the inner 500pc of the Galaxy is consistent with recent predictions for the dynamical evolution of gas flows in the centre of the Milky Way. We confirm a recent finding that the dense gas in the inner 100pc has an oscillatory kinematic structure with characteristic length scale of ~20pc, and also identify similar oscillatory kinematic structure in the gas at radii larger than 100pc. Finally, we make all of the above fits and the remaining HOPS data cubes across the 100 square degrees of the survey available to the community., Comment: 53 pages, 34 figures, 4 tables. Submitted MNRAS. Paper with full resolution images can be downloaded here: http://www.astro.ljmu.ac.uk/~snl/hops_p3.pdf

Published
2017
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10. Illuminating the past 8 billion years of cold gas towards two gravitationally lensed quasars

Author

Allison, J. R., Moss, V. A., Macquart, J. -P., Curran, S. J., Duchesne, S. W., Mahony, E. K., Sadler, E. M., Whiting, M. T., Bannister, K. W., Chippendale, A. P., Edwards, P. G., Harvey-Smith, L., Heywood, I., Indermuehle, B. T., Lenc, E., Marvil, J., McConnell, D., and Sault, R. J.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Using the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP BETA), we have carried out the first $z = 0 - 1$ survey for HI and OH absorption towards the gravitationally lensed quasars PKSB1830$-$211 and MGJ0414$+$0534. Although we detected all previously reported intervening systems towards PKSB1830$-$211, in the case of MGJ0414+0534 three systems were not found, indicating that the original identifications may have been confused with radio frequency interference. Given the sensitivity of our data, we find that our detection yield is consistent with the expected frequency of intervening HI systems estimated from previous surveys for 21-cm emission in nearby galaxies and $z \sim 3$ damped Lyman $\alpha$ absorbers. We find spectral variability in the $z = 0.886$ face-on spiral galaxy towards PKSB1830$-$211, from observations undertaken with the Westerbork Synthesis Radio Telescope in 1997/1998 and ASKAP BETA in 2014/2015. The HI equivalent width varies by a few per cent over approximately yearly time-scales. This long-term spectral variability is correlated between the north-east and south-west images of the core, and with the total flux density of the source, implying that it is observationally coupled to intrinsic changes in the quasar. The absence of any detectable variability in the ratio of HI associated with the two core images is in stark contrast to the behaviour previously seen in the molecular lines. We therefore infer that coherent opaque HI structures in this galaxy are larger than the parsec-scale molecular clouds found at mm-wavelengths., Comment: 19 pages, 11 figures, published in MNRAS

Published
2016
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11. The Australian Square Kilometre Array Pathfinder: Performance of the Boolardy Engineering Test Array

Author

McConnell, D., Allison, J. R., Bannister, K., Bell, M. E., Bignall, H. E., Chippendale, A. P., Edwards, P. G., Harvey-Smith, L., Hegarty, S., Heywood, I., Hotan, A. W., Indermuehle, B. T., Lenc, E., Marvil, J., Popping, A., Raja, W., Reynolds, J. E., Sault, R. J., Serra, P., Voronkov, M. A., Whiting, M., Amy, S. W., Axtens, P., Ball, L., Bateman, T. J., Bock, D. C. -J., Bolton, R., Brodrick, D., Brothers, M., Brown, A. J., Bunton, J. D., Cheng, W., Cornwell, T., DeBoer, D., Feain, I., Gough, R., Gupta, N., Guzman, J. C., Hampson, G. A., Hay, S., Hayman, D. B., Hoyle, S., Humphreys, B., Jacka, C., Jackson, C. A., Jackson, S., Jeganathan, K., Joseph, J., Koribalski, B. S., Leach, M., Lensson, E. S., MacLeod, A., Mackay, S., Marquarding, M., McClure-Griffiths, N. M., Mirtschin, P., Mitchell, D., Neuhold, S., Ng, A., Norris, R., Pearce, S., Qiao, R. Y., Schinckel, A. E. T., Shields, M., Shimwell, T. W., Storey, M., Troup, E., Turner, B., Tuthill, J., Tzioumis, A., Wark, R. M., Westmeier, T., Wilson, C., and Wilson, T.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We describe the performance of the Boolardy Engineering Test Array (BETA), the prototype for the Australian Square Kilometre Array Pathfinder telescope ASKAP. BETA is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarization beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of BETA's performance: sensitivity, beam characteristics, polarimetric properties and image quality. We summarise the astronomical science that it has produced and draw lessons from operating BETA that will be relevant to the commissioning and operation of the final ASKAP telescope., Comment: Accepted for publication in PASA

Published
2016
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12. The radio spectral energy distribution of infrared-faint radio sources

Author

Herzog, A., Norris, R. P., Middelberg, E., Seymour, N., Spitler, L. R., Emonts, B. H. C., Franzen, T. M. O., Hunstead, R., Intema, H. T., Marvil, J., Parker, Q. A., Sirothia, S. K., Hurley-Walker, N., Bell, M., Bernardi, G., Bowman, J. D., Briggs, F., Cappallo, R. J., Callingham, J. R., Deshpande, A. A., Dwarakanath, K. S., For, B. -Q., Greenhill, L. J., Hancock, P., Hazelton, B. J., Hindson, L., Johnston-Hollitt, M., Kapinska, A. D., Kaplan, D. L., Lenc, E., Lonsdale, C. J., McKinley, B., McWhirter, S. R., Mitchell, D. A., Morales, M. F., Morgan, E., Morgan, J., Oberoi, D., Offringa, A., Ord, S. M., Prabu, T., Procopio, P., Shankar, N. Udaya, Srivani, K. S., Staveley-Smith, L., Subrahmanyan, R., Tingay, S. J., Wayth, R. B., Webster, R. L., Williams, A., Williams, C. L., Wu, C., Zheng, Q., Chippendale, A. P., Harvey-Smith, L., Heywood, I., Indermuehle, B., Popping, A., Sault, R. J., and Whiting, M. T.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Infrared-faint radio sources (IFRS) are a class of radio-loud (RL) active galactic nuclei (AGN) at high redshifts (z > 1.7) that are characterised by their relative infrared faintness, resulting in enormous radio-to-infrared flux density ratios of up to several thousand. We aim to test the hypothesis that IFRS are young AGN, particularly GHz peaked-spectrum (GPS) and compact steep-spectrum (CSS) sources that have a low frequency turnover. We use the rich radio data set available for the Australia Telescope Large Area Survey fields, covering the frequency range between 150 MHz and 34 GHz with up to 19 wavebands from different telescopes, and build radio spectral energy distributions (SEDs) for 34 IFRS. We then study the radio properties of this class of object with respect to turnover, spectral index, and behaviour towards higher frequencies. We also present the highest-frequency radio observations of an IFRS, observed with the Plateau de Bure Interferometer at 105 GHz, and model the multi-wavelength and radio-far-infrared SED of this source. We find IFRS usually follow single power laws down to observed frequencies of around 150 MHz. Mostly, the radio SEDs are steep, but we also find ultra-steep SEDs. In particular, IFRS show statistically significantly steeper radio SEDs than the broader RL AGN population. Our analysis reveals that the fractions of GPS and CSS sources in the population of IFRS are consistent with the fractions in the broader RL AGN population. We find that at least 18% of IFRS contain young AGN, although the fraction might be significantly higher as suggested by the steep SEDs and the compact morphology of IFRS. The detailed multi-wavelength SED modelling of one IFRS shows that it is different from ordinary AGN, although it is consistent with a composite starburst-AGN model with a star formation rate of 170 solar masses per year., Comment: 25 pages, 7 figures, 5 tables, accepted for publication in A&A

Published
2016
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13. Supplement: Localization and broadband follow-up of the gravitational-wave transient GW150914

Author

Abbott, B. P., Abbott, R., Abbott, T. D., Abernathy, M. R., Acernese, F., Ackley, K., Adams, C., Adams, T., Addesso, P., Adhikari, R. X., Adya, V. B., Affeldt, C., Agathos, M., Agatsuma, K., Aggarwal, N., Aguiar, O. D., Aiello, L., Ain, A., Ajith, P., Allen, B., Allocca, A., Altin, P. A., Anderson, S. B., Anderson, W. G., Arai, K., Araya, M. C., Arceneaux, C. C., Areeda, J. S., Arnaud, N., Arun, K. G., Ascenzi, S., Ashton, G., Ast, M., Aston, S. M., Astone, P., Aufmuth, P., Aulbert, C., Babak, S., Bacon, P., Bader, M. K. M., Baker, P. T., Baldaccini, F., Ballardin, G., Ballmer, S. W., Barayoga, J. C., Barclay, S. E., Barish, B. C., Barker, D., Barone, F., Barr, B., Barsotti, L., Barsuglia, M., Barta, D., Barthelmy, S., Bartlett, J., Bartos, I., Bassiri, R., Basti, A., Batch, J. C., Baune, C., Bavigadda, V., Bazzan, M., Behnke, B., Bejger, M., Bell, A. S., Bell, C. J., Berger, B. K., Bergman, J., Bergmann, G., Berry, C. P. L., Bersanetti, D., Bertolini, A., Betzwieser, J., Bhagwat, S., Bhandare, R., Bilenko, I. A., Billingsley, G., Birch, J., Birney, R., Biscans, S., Bisht, A., Bitossi, M., Biwer, C., Bizouard, M. A., Blackburn, J. K., Blair, C. D., Blair, D. G., Blair, R. M., Bloemen, S., Bock, O., Bodiya, T. P., Boer, M., Bogaert, G., Bogan, C., Bohe, A., Bojtos, P., Bond, C., Bondu, F., Bonnand, R., Boom, B. A., Bork, R., Boschi, V., Bose, S., Bouffanais, Y., Bozzi, A., Bradaschia, C., Brady, P. R., Braginsky, V. B., Branchesi, M., Brau, J. E., Briant, T., Brillet, A., Brinkmann, M., Brisson, V., Brockill, P., Brooks, A. F., Brown, D. A., Brown, D. D., Brown, N. M., Buchanan, C. C., Buikema, A., Bulik, T., Bulten, H. J., Buonanno, A., Buskulic, D., Buy, C., Byer, R. L., Cadonati, L., Cagnoli, G., Cahillane, C., Bustillo, J. C., Callister, T., Calloni, E., Camp, J. B., Cannon, K. C., Cao, J., Capano, C. D., Capocasa, E., Carbognani, F., Caride, S., Diaz, J. 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Subjects
Astrophysics - High Energy Astrophysical Phenomena, General Relativity and Quantum Cosmology
Abstract

This Supplement provides supporting material for arXiv:1602.08492 . We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands., Comment: For the main Letter, see arXiv:1602.08492

Published
2016
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14. High-velocity OH megamasers in IRAS 20100-4156: Evidence for a Supermassive Black Hole

Author

Harvey-Smith, L., Allison, J. R., Green, J. A., Bannister, K. W., Chippendale, A., Edwards, P. G., Heywood, I., Hotan, A. W., Lenc, E., Marvil, J., McConnell, D., Phillips, C. P., Sault, R. J., Serra, P., Stevens, J., Voronkov, M., and Whiting, M.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We report the discovery of new, high-velocity narrow-line components of the OH megamaser in IRAS 20100-4156. Results from the Australian Square Kilometre Array Pathfinder (ASKAP)'s Boolardy Engineering Test Array (BETA) and the Australia Telescope Compact Array (ATCA) provide two independent measurements of the OH megamaser spectrum. We found evidence for OH megamaser clumps at $-$409 and $-$562 km/s (blue-shifted) from the systemic velocity of the galaxy, in addition to the lines previously known. The presence of such high velocities in the molecular emission from IRAS 20100$-$4156 could be explained by a ~50 pc molecular ring enclosing an approximately 3.8 billion solar mass black hole. We also discuss two alternatives, i.e. that the narrow-line masers are dynamically coupled to the wind driven by the active galactic nucleus or they are associated with two separate galactic nuclei. The comparison between the BETA and ATCA spectra provides another scientific verification of ASKAP's BETA. Our data, combined with previous measurements of the source enabled us to study the variability of the source over a twenty-six year period. The flux density of the brightest OH maser components has reduced by more than a factor of two between 1988 and 2015, whereas a secondary narrow-line component has more than doubled in the same time. Plans for high-resolution VLBI follow-up of this source are discussed, as are prospects for discovering new OH megamasers during the ASKAP early science program., Comment: Accepted to MNRAS. Seven pages, three figures

Published
2016
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15. Localization and broadband follow-up of the gravitational-wave transient GW150914

Author

Abbott, B. P., Abbott, R., Abbott, T. D., Abernathy, M. R., Acernese, F., Ackley, K., Adams, C., Adams, T., Addesso, P., Adhikari, R. X., Adya, V. B., Affeldt, C., Agathos, M., Agatsuma, K., Aggarwal, N., Aguiar, O. D., Aiello, L., Ain, A., Ajith, P., Allen, B., Allocca, A., Altin, P. A., Anderson, S. B., Anderson, W. G., Arai, K., Araya, M. C., Arceneaux, C. C., Areeda, J. S., Arnaud, N., Arun, K. G., Ascenzi, S., Ashton, G., Ast, M., Aston, S. M., Astone, P., Aufmuth, P., Aulbert, C., Babak, S., Bacon, P., Bader, M. K. M., Baker, P. T., Baldaccini, F., Ballardin, G., Ballmer, S. W., Barayoga, J. C., Barclay, S. E., Barish, B. C., Barker, D., Barone, F., Barr, B., Barsotti, L., Barsuglia, M., Barta, D., Barthelmy, S., Bartlett, J., Bartos, I., Bassiri, R., Basti, A., Batch, J. C., Baune, C., Bavigadda, V., Bazzan, M., Behnke, B., Bejger, M., Bell, A. S., Bell, C. J., Berger, B. K., Bergman, J., Bergmann, G., Berry, C. P. L., Bersanetti, D., Bertolini, A., Betzwieser, J., Bhagwat, S., Bhandare, R., Bilenko, I. A., Billingsley, G., Birch, J., Birney, R., Biscans, S., Bisht, A., Bitossi, M., Biwer, C., Bizouard, M. A., Blackburn, J. K., Blair, C. D., Blair, D. G., Blair, R. M., Bloemen, S., Bock, O., Bodiya, T. P., Boer, M., Bogaert, G., Bogan, C., Bohe, A., Bojtos, P., Bond, C., Bondu, F., Bonnand, R., Boom, B. A., Bork, R., Boschi, V., Bose, S., Bouffanais, Y., Bozzi, A., Bradaschia, C., Brady, P. R., Braginsky, V. B., Branchesi, M., Brau, J. E., Briant, T., Brillet, A., Brinkmann, M., Brisson, V., Brockill, P., Brooks, A. F., Brown, D. A., Brown, D. D., Brown, N. M., Buchanan, C. C., Buikema, A., Bulik, T., Bulten, H. J., Buonanno, A., Buskulic, D., Buy, C., Byer, R. L., Cadonati, L., Cagnoli, G., Cahillane, C., Bustillo, J. C., Callister, T., Calloni, E., Camp, J. B., Cannon, K. C., Cao, J., Capano, C. D., Capocasa, E., Carbognani, F., Caride, S., Diaz, J. 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M., Jenke, P., Wilson-Hodge, C. A., Bhat, P. N., Bissaldi, E., Cleveland, W., Fitzpatrick, G., Giles, M. M., Gibby, M. H., Greiner, J., von Kienlin, A., Kippen, R. M., McBreen, S., Mailyan, B., Meegan, C. A., Paciesas, W. S., Preece, R. D., Roberts, O., Sparke, L., Stanbro, M., Toelge, K., Veres, P., Yu, H. -F., Blackburn, L., Ackermann, M., Ajello, M., Albert, A., Anderson, B., Atwood, W. B., Axelsson, M., Baldini, L., Barbiellini, G., Bastieri, D., Bellazzini, R., Blandford, R. D., Bloom, E. D., Bonino, R., Bottacini, E., Brandt, T. J., Bruel, P., Buson, S., Caliandro, G. A., Cameron, R. A., Caragiulo, M., Caraveo, P. A., Cavazzuti, E., Charles, E., Chekhtman, A., Chiang, J., Chiaro, G., Ciprini, S., Cohen-Tanugi, J., Cominsky, L. R., Costanza, F., Cuoco, A., D'Ammando, F., de Palma, F., Desiante, R., Digel, S. W., Di Lalla, N., Di Mauro, M., Di Venere, L., Domínguez, A., Drell, P. S., Dubois, R., Favuzzi, C., Ferrara, E. C., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giommi, P., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Gomez-Vargas, G. A., Green, D., Grenier, I. A., Grove, J. E., Guiriec, S., Hadasch, D., Harding, A. K., Hays, E., Hewitt, J. W., Hill, A. B., Horan, D., Jogler, T., Jóhannesson, G., Johnson, A. S., Kensei, S., Kocevski, D., Kuss, M., La Mura, G., Larsson, S., Latronico, L., Li, J., Li, L., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J., Maldera, S., Manfreda, A., Marelli, M., Mayer, M., Mazziotta, M. N., McEnery, J. E., Meyer, M., Michelson, P. F., Mirabal, N., Mizuno, T., Moiseev, A. A., Monzani, M. E., Moretti, E., Morselli, A., Moskalenko, I. V., Negro, M., Nuss, E., Ohsugi, T., Omodei, N., Orienti, M., Orlando, E., Ormes, J. F., Paneque, D., Perkins, J. S., Pesce-Rollins, M., Piron, F., Pivato, G., Porter, T. A., Racusin, J. L., Rainò, S., Rando, R., Razzaque, S., Reimer, A., Reimer, O., Salvetti, D., Parkinson, P. M. Saz, Sgrò, C., Simone, D., Siskind, E. J., Spada, F., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Thayer, J. B., Thompson, D. J., Tibaldo, L., Torres, D. F., Troja, E., Uchiyama, Y., Venters, T. M., Vianello, G., Wood, K. S., Wood, M., Zhu, S., Zimmer, S., Brocato, E., Cappellaro, E., Covino, S., Grado, A., Nicastro, L., Palazzi, E., Pian, E., Amati, L., Antonelli, L. A., Capaccioli, M., D'Avanzo, P., D'Elia, V., Getman, F., Giuffrida, G., Iannicola, G., Limatola, L., Lisi, M., Marinoni, S., Marrese, P., Melandri, A., Piranomonte, S., Possenti, A., Pulone, L., Rossi, A., Stamerra, A., Stella, L., Testa, V., Tomasella, L., Yang, S., Bazzano, A., Bozzo, E., Brandt, S., Courvoisier, T. J. -L., Ferrigno, C., Hanlon, L., Kuulkers, E., Laurent, P., Mereghetti, S., Roques, J. P., Savchenko, V., Ubertini, P., Kasliwal, M. M., Singer, L. P., Cao, Y., Duggan, G., Kulkarni, S. R., Bhalerao, V., Miller, A. A., Barlow, T., Bellm, E., Manulis, I., Rana, J., Laher, R., Masci, F., Surace, J., Rebbapragada, U., Van Sistine, A., Sesar, B., Perley, D., Ferreti, R., Prince, T., Kendrick, R., Horesh, A., Hurley, K., Golenetskii, S. V., Aptekar, R. L., Frederiks, D. D., Svinkin, D. S., Rau, A., Zhang, X., Smith, D. M., Cline, T., Krimm, H., Abe, F., Doi, M., Fujisawa, K., Kawabata, K. S., Morokuma, T., Motohara, K., Tanaka, M., Ohta, K., Yanagisawa, K., Yoshida, M., Baltay, C., Rabinowitz, D., Ellman, N., Rostami, S., Bersier, D. F., Bode, M. F., Collins, C. A., Copperwheat, C. M., Darnley, M. J., Galloway, D. K., Gomboc, A., Kobayashi, S., Mazzali, P., Mundell, C. G., Piascik, A. S., Pollacco, Don, Steele, I. A., Ulaczyk, K., Broderick, J. W., Fender, R. P., Jonker, P. G., Rowlinson, A., Stappers, B. W., Wijers, R. A. M. J., Lipunov, V., Gorbovskoy, E., Tyurina, N., Kornilov, V., Balanutsa, P., Kuznetsov, A., Buckley, D., Rebolo, R., Serra-Ricart, M., Israelian, G., Budnev, N. M., Gress, O., Ivanov, K., Poleshuk, V., Tlatov, A., Yurkov, V., Kawai, N., Serino, M., Negoro, H., Nakahira, S., Mihara, T., Tomida, H., Ueno, S., Tsunemi, H., Matsuoka, M., Croft, S., Feng, L., Franzen, T. M. O., Gaensler, B. M., Johnston-Hollitt, M., Kaplan, D. L., Morales, M. F., Tingay, S. J., Wayth, R. B., Williams, A., Smartt, S. J., Chambers, K. C., Smith, K. W., Huber, M. E., Young, D. R., Wright, D. E., Schultz, A., Denneau, L., Flewelling, H., Magnier, E. A., Primak, N., Rest, A., Sherstyuk, A., Stalder, B., Stubbs, C. W., Tonry, J., Waters, C., Willman, M., E., F. Olivares, Campbell, H., Kotak, R., Sollerman, J., Smith, M., Dennefeld, M., Anderson, J. P., Botticella, M. T., Chen, T. -W., Valle, M. D., Elias-Rosa, N., Fraser, M., Inserra, C., Kankare, E., Kupfer, T., Harmanen, J., Galbany, L., Guillou, L. Le, Lyman, J. D., Maguire, K., Mitra, A., Nicholl, M., Razza, A., Terreran, G., Valenti, S., Gal-Yam, A., Ćwiek, A., Ćwiok, M., Mankiewicz, L., Opiela, R., Zaremba, M., Żarnecki, A. F., Onken, C. A., Scalzo, R. A., Schmidt, B. P., Wolf, C., Yuan, F., Evans, P. A., Kennea, J. A., Burrows, D. N., Campana, S., Cenko, S. B., Marshall, F. E., Nousek, J., O'Brien, P., Osborne, J. P., Palmer, D., Perri, M., Siegel, M., Tagliaferri, G., Klotz, A., Turpin, D., Laugier, R., Beroiz, M., Peñuela, T., Macri, L. M., Oelkers, R. J., Lambas, D. G., Vrech, R., Cabral, J., Colazo, C., Dominguez, M., Sanchez, B., Gurovich, S., Lares, M., Marshall, J. L., DePoy, D. L., Padilla, N., Pereyra, N. A., Benacquista, M., Tanvir, N. R., Wiersema, K., Levan, A. J., Steeghs, D., Hjorth, J., Fynbo, J. P. U., Malesani, D., Milvang-Jensen, B., Watson, D., Irwin, M., Fernandez, C. G., McMahon, R. G., Banerji, M., Gonzalez-Solares, E., Schulze, S., Postigo, A. de U., Thoene, C. C., Cano, Z., and Rosswog, S.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, General Relativity and Quantum Cosmology
Abstract

A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams., Comment: For Supplement, see https://arxiv.org/abs/1604.07864

Published
2016
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16. Wide-field broadband radio imaging with phased array feeds: a pilot multi-epoch continuum survey with ASKAP-BETA

Author

Heywood, I., Bannister, K. W., Marvil, J., Allison, J. R., Ball, L., Bell, M. E., Bock, D. C. -J., Brothers, M., Bunton, J. D., Chippendale, A. P., Cooray, F., Cornwell, T. J., DeBoer, D., Edwards, P., Gough, R., Gupta, N., Harvey-Smith, L., Hay, S., Hotan, A. W., Indermuehle, B., Jacka, C., Jackson, C. A., Johnston, S., Kimball, A. E., Koribalski, B. S., Lenc, E., Macleod, A., McClure-Griffiths, N., McConnell, D., Mirtschin, P., Murphy, T., Neuhold, S., Norris, R. P., Pearce, S., Popping, A., Qiao, R. Y., Reynolds, J. E., Sadler, E. M., Sault, R. J., Schinckel, A. E. T., Serra, P., Shimwell, T. W., Stevens, J., Tuthill, J., Tzioumis, A., Voronkov, M. A., Westmeier, T., and Whiting, M. T.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Boolardy Engineering Test Array is a 6 x 12 m dish interferometer and the prototype of the Australian Square Kilometre Array Pathfinder (ASKAP), equipped with the first generation of ASKAP's phased array feed (PAF) receivers. These facilitate rapid wide-area imaging via the deployment of simultaneous multiple beams within a 30 square degree field of view. By cycling the array through 12 interleaved pointing positions and using 9 digitally formed beams we effectively mimic a traditional 1 hour x 108 pointing survey, covering 150 square degrees over 711 - 1015 MHz in 12 hours of observing time. Three such observations were executed over the course of a week. We verify the full bandwidth continuum imaging performance and stability of the system via self-consistency checks and comparisons to existing radio data. The combined three epoch image has arcminute resolution and a 1-sigma thermal noise level of 375 micro-Jy per beam, although the effective noise is a factor 3 higher due to residual sidelobe confusion. From this we derive a catalogue of 3,722 discrete radio components, using the 35 percent fractional bandwidth to measure in-band spectral indices for 1,037 of them. A search for transient events reveals one significantly variable source within the survey area. The survey covers approximately two-thirds of the Spitzer South Pole Telescope Deep Field. This pilot project demonstrates the viability and potential of using PAFs to rapidly and accurately survey the sky at radio wavelengths., Comment: 20 pages, 13 figures, 4 tables. Accepted for publication in MNRAS

Published
2016
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17. A pilot ASKAP survey of radio transient events in the region around the intermittent pulsar PSR J1107-5907

Author

Hobbs, G., Heywood, I., Bell, M. E., Kerr, M., Rowlinson, A., Johnston, S., Shannon, R. M., Voronkov, M. A., Ward, C., Banyer, J., Hancock, P. J., Murphy, Tara, Allison, J. R., Amy, S. W., Ball, L., Bannister, K., Bock, D. C. -J., Brodrick, D., Brothers, M., Brown, A. J., Bunton, J. D., Chapman, J., Chippendale, A. P., Chung, Y., DeBoer, D., Diamond, P., Edwards, P. G., Ekers, R., Ferris, R. H., Forsyth, R., Gough, R., Grancea, A., Gupta, N., Harvey-Smith, L., Hay, S., Hayman, D. B., Hotan, A. W., Hoyle, S., Humphreys, B., Indermuehle, B., Jacka, C. E., Jackson, C. A., Jackson, S., Jeganathan, K., Joseph, J, Kendall, R., Kiraly, D., Koribalski, B., Leach, M., Lenc, E., MacLeod, A., Mader, S., Marquarding, M., Marvil, J., McClure-Griffiths, N., McConnell, D., Mirtschin, P., Neuhold, S., Ng, A., Norris, R. P., O'Sullivan, J., Pearce, S., Phillips, C. J., Popping, A., Qiao, R. Y., Reynolds, J. E., Roberts, P., Sault, R. J., Schinckel, A. E. T., Serra, P., Shaw, R., Shimwell, T. W., Storey, M., Sweetnam, A. W., Tzioumis, A., Westmeier, T., Whiting, M., and Wilson, C. D.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We use observations from the Boolardy Engineering Test Array (BETA) of the Australian Square Kilometre Array Pathfinder (ASKAP) telescope to search for transient radio sources in the field around the intermittent pulsar PSR J1107-5907. The pulsar is thought to switch between an "off" state in which no emission is detectable, a weak state and a strong state. We ran three independent transient detection pipelines on two-minute snapshot images from a 13 hour BETA observation in order to 1) study the emission from the pulsar, 2) search for other transient emission from elsewhere in the image and 3) to compare the results from the different transient detection pipelines. The pulsar was easily detected as a transient source and, over the course of the observations, it switched into the strong state three times giving a typical timescale between the strong emission states of 3.7 hours. After the first switch it remained in the strong state for almost 40 minutes. The other strong states lasted less than 4 minutes. The second state change was confirmed using observations with the Parkes radio telescope. No other transient events were found and we place constraints on the surface density of such events on these timescales. The high sensitivity Parkes observations enabled us to detect individual bright pulses during the weak state and to study the strong state over a wide observing band. We conclude by showing that future transient surveys with ASKAP will have the potential to probe the intermittent pulsar population., Comment: Accepted by MNRAS

Published
2015
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18. Tracing the neutral gas environments of young radio AGN with ASKAP

Author

Allison, J. R., Sadler, E. M., Moss, V. A., Harvey-Smith, L., Heywood, I., Indermuehle, B. T., McConnell, D., Sault, R. J., and Whiting, M. T.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

At present neutral atomic hydrogen (HI) gas in galaxies at redshifts above $z \sim 0.3$ (the extent of 21-cm emission surveys in individual galaxies) and below $z \sim 1.7$ (where the Lyman-$\alpha$ line is not observable with ground-based telescopes) has remained largely unexplored. The advent of precursor telescopes to the Square Kilometre Array will allow us to conduct the first systematic radio-selected 21-cm absorption surveys for HI over these redshifts. While HI absorption is a tracer of the reservoir of cold neutral gas in galaxies available for star formation, it can also be used to reveal the extreme kinematics associated with jet-driven neutral outflows in radio-loud active galactic nuclei. Using the six-antenna Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder, we have demonstrated that in a single frequency tuning we can detect HI absorption over a broad range of redshifts between $z = 0.4$ and $1.0$. As part of our early science and commissioning program, we are now carrying out a search for absorption towards a sample of the brightest GPS and CSS sources in the southern sky. These intrinsically compact sources present us with an opportunity to study the circumunuclear region of recently re-started radio galaxies, in some cases showing direct evidence of mechanical feedback through jet-driven outflows. With the sensitivity of the full ASKAP array we will be able to study the kinematics of atomic gas in a few thousand radio galaxies, testing models of radio jet feedback well beyond the nearby Universe, Comment: 5 pages, 3 figures. Accepted for publication in Astronomische Nachrichten. In proceedings of the "5th Workshop on CSS and GPS radio sources", held in Rimini (Italy) in May 2015

Published
2015
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19. ASKAP HI imaging of the galaxy group IC 1459

Author

Serra, P., Koribalski, B., Kilborn, V., Allison, J. R., Amy, S. W., Ball, L., Bannister, K., Bell, M. E., Bock, D. C. -J., Bolton, R., Bowen, M., Boyle, B., Broadhurst, S., Brodrick, D., Brothers, M., Bunton, J. D., Chapman, J., Cheng, W., Chippendale, A. P., Chung, Y., Cooray, F., Cornwell, T., DeBoer, D., Diamond, P., Forsyth, R., Gough, R., Gupta, N., Hampson, G. A., Harvey-Smith, L., Hay, S., Hayman, D. B., Heywood, I., Hotan, A. W., Hoyle, S., Humphreys, B., Indermuehle, B., Jacka, C., Jackson, C. A., Jackson, S., Jeganathan, K., Johnston, S., Joseph, J, Kamphuis, P., Leach, M., Lenc, E., Lensson, E., Mackay, S., Marquarding, M., Marvil, J., McClure-Griffiths, N., McConnell, D., Meyer, M., Mirtschin, P., Neuhold, S., Ng, A., Norris, R. P., O'Sullivan, J., Pathikulangara, J., Pearce, S., Phillips, C., Popping, A., Qiao, R. Y., Reynolds, J. E., Roberts, P., Sault, R. J., Schinckel, A. E. T., Shaw, R., Shimwell, T. W., Staveley-Smith, L., Storey, M., Sweetnam, A. W., Troup, E., Tzioumis, A., Voronkov, M. A., Westmeier, T., Whiting, M., Wilson, C., Wong, O. I., and Wu, X.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present HI imaging of the galaxy group IC 1459 carried out with six antennas of the Australian SKA Pathfinder equipped with phased-array feeds. We detect and resolve HI in eleven galaxies down to a column density of $\sim10^{20}$ cm$^{-2}$ inside a ~6 deg$^2$ field and with a resolution of ~1 arcmin on the sky and ~8 km/s in velocity. We present HI images, velocity fields and integrated spectra of all detections, and highlight the discovery of three HI clouds -- two in the proximity of the galaxy IC 5270 and one close to NGC 7418. Each cloud has an HI mass of $10^9$ M$_\odot$ and accounts for ~15% of the HI associated with its host galaxy. Available images at ultraviolet, optical and infrared wavelengths do not reveal any clear stellar counterpart of any of the clouds, suggesting that they are not gas-rich dwarf neighbours of IC 5270 and NGC 7418. Using Parkes data we find evidence of additional extended, low-column-density HI emission around IC 5270, indicating that the clouds are the tip of the iceberg of a larger system of gas surrounding this galaxy. This result adds to the body of evidence on the presence of intra-group gas within the IC 1459 group. Altogether, the HI found outside galaxies in this group amounts to several times $10^9$ M$_\odot$, at least 10% of the HI contained inside galaxies. This suggests a substantial flow of gas in and out of galaxies during the several billion years of the group's evolution., Comment: MNRAS accepted

Published
2015
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20. Discovery of HI gas in a young radio galaxy at $z = 0.44$ using the Australian Square Kilometre Array Pathfinder

Author

Allison, J. R., Sadler, E. M., Moss, V. A., Whiting, M. T., Hunstead, R. W., Pracy, M. B., Curran, S. J., Croom, S. M., Glowacki, M., Morganti, R., Shabala, S. S., Zwaan, M. A., Allen, G., Amy, S. W., Axtens, P., Ball, L., Bannister, K. W., Barker, S., Bell, M. E., Bock, D. C. -J., Bolton, R., Bowen, M., Boyle, B., Braun, R., Broadhurst, S., Brodrick, D., Brothers, M., Brown, A., Bunton, J. D., Cantrall, C., Chapman, J., Cheng, W., Chippendale, A. P., Chung, Y., Cooray, F., Cornwell, T., DeBoer, D., Diamond, P., Edwards, P. G., Ekers, R., Feain, I., Ferris, R. H., Forsyth, R., Gough, R., Grancea, A., Gupta, N., Guzman, J. C., Hampson, G., Harvey-Smith, L., Haskins, C., Hay, S., Hayman, D. B., Heywood, I., Hotan, A. W., Hoyle, S., Humphreys, B., Indermuehle, B. T., Jacka, C., Jackson, C., Jackson, S., Jeganathan, K., Johnston, S., Joseph, J., Kendall, R., Kesteven, M., Kiraly, D., Koribalski, B. S., Leach, M., Lenc, E., Lensson, E., Mackay, S., Macleod, A., Marquarding, M., Marvil, J., McClure-Griffiths, N., McConnell, D., Mirtschin, P., Norris, R. P., Neuhold, S., Ng, A., O'Sullivan, J., Pathikulangara, J., Pearce, S., Phillips, C., Popping, A., Qiao, R. Y., Reynolds, J. E., Roberts, P., Sault, R. J., Schinckel, A., Serra, P., Shaw, R., Shields, M., Shimwell, T., Storey, M., Sweetnam, T., Troup, E., Turner, B., Tuthill, J., Tzioumis, A., Voronkov, M. A., Westmeier, T., and Wilson, C. D.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

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$^{-1}$., Comment: 18 pages, 11 figures, accepted for publication in MNRAS

Published
2015
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21. The Australian Square Kilometre Array Pathfinder: System Architecture and Specifications of the Boolardy Engineering Test Array

Author

Hotan, A. W., Bunton, J. D., Harvey-Smith, L., Humphreys, B., Jeffs, B. D., Shimwell, T., Tuthill, J., Voronkov, M., Allen, G., Amy, S., Ardern, K., Axtens, P., Ball, L., Bannister, K., Barker, S., Bateman, T., Beresford, R., Bock, D., Bolton, R., Bowen, M., Boyle, B., Braun, R., Broadhurst, S., Brodrick, D., Brooks, K., Brothers, M., Brown, A., Cantrall, C., Carrad, G., Chapman, J., Cheng, W., Chippendale, A., Chung, Y., Cooray, F., Cornwell, T., Davis, E., de Souza, L., DeBoer, D., Diamond, P., Edwards, P., Ekers, R., Feain, I., Ferris, D., Forsyth, R., Gough, R., Grancea, A., Gupta, N., Guzman, JC., Hampson, G., Haskins, C., Hay, S., Hayman, D., Hoyle, S., Jacka, C., Jackson, C., Jackson, S., Jeganathan, K., Johnston, S., Joseph, J., Kendall, R., Kesteven, M., Kiraly, D., Koribalski, B., Leach, M., Lenc, E., Lensson, E., Li, L., Mackay, S., Macleod, A., Maher, T., Marquarding, M., McClure-Griffiths, N., McConnell, D., Mickle, S., Mirtschin, P., Norris, R., Neuhold, S., Ng, A., O'Sullivan, J., Pathikulangara, J., Pearce, S., Phillips, C., Qiao, RY., Reynolds, J. E., Rispler, A., Roberts, P., Roxby, D., Schinckel, A., Shaw, R., Shields, M., Storey, M., Sweetnam, T., Troup, E., Turner, B., Tzioumis, A., Westmeier, T., Whiting, M., Wilson, C., Wilson, T., Wormnes, K., and Wu, X.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

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., Comment: 17 pages, 12 figures, accepted for publication in PASA

Published
2014
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22. Formation of the compact jets in the black hole GX 339-4

Author

Corbel, S., Aussel, H., Broderick, J. W., Chanial, P., Coriat, M., Maury, A. J., Buxton, M., Tzioumis, J. A. Tomsick A., Markoff, S., Rodriguez, J., Bailyn, C., Brocksopp, C., Fender, R., Petrucci, P. O., Cadolle-Bel, M., Calvelo, D., and Harvey-Smith, L.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Galactic black hole binaries produce powerful outflows with emit over almost the entire electromagnetic spectrum. Here, we report the first detection with the Herschel observatory of a variable far-infrared source associated with the compact jets of the black hole transient GX 339-4 during the decay of its recent 2010-2011 outburst, after the transition to the hard state. We also outline the results of very sensitive radio observations conducted with the Australia Telescope Compact Array, along with a series of near-infrared, optical (OIR) and X-ray observations, allowing for the first time the re-ignition of the compact jets to be observed over a wide range of wavelengths. The compact jets first turn on at radio frequencies with an optically thin spectrum that later evolves to optically thick synchrotron emission. An OIR reflare is observed about ten days after the onset of radio and hard X-ray emission, likely reflecting the necessary time to build up enough density, as well as to have acceleration (e.g. through shocks) along an extended region in the jets. The Herschel measurements are consistent with an extrapolation of the radio inverted power-law spectrum, but they highlight a more complex radio to OIR spectral energy distribution for the jets., Comment: Accepted for publication in MNRAS Letter, 6 pages, 3 Figures + 1 online Table

Published
2013
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23. The H2O southern Galactic Plane Survey(HOPS): NH3 (1,1) and (2,2) catalogues

Author

Purcell, C. R., Longmore, S. N., Walsh, A. J., Whiting, M. T., Breen, S. L., Britton, T., Brooks, K. J., Burton, M. G., Cunningham, M. R., Green, J. A., Harvey-Smith, L., Hindson, L., Hoare, M. G., Indermuehle, B., Jones, P. A., Lo, N., Lowe, V., Phillips, C. J., Thompson, M. A., Urquhart, J. S., Voronkov, M. A., and White, G. L.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

The H2O Southern Galactic Plane Survey (HOPS) has mapped a 100 degree strip of the Galactic plane (-70deg > l > 30deg, |b| < 0.5deg) using the 22-m Mopra antenna at 12-mm wavelengths. Observations were conducted in on-the-fly mode using the Mopra spectrometer (MOPS), targeting water masers, thermal molecular emission and radio-recombination lines. Foremost among the thermal lines are the 23 GHz transitions of NH3 J,K = (1,1) and (2,2), which trace the densest parts of molecular clouds (n > 10^4 cm^{-3}). In this paper we present the NH3 (1,1) and (2,2) data, which have a resolution of 2 arcmin and cover a velocity range of +/-200 km/s. The median sensitivity of the NH3 data-cubes is sigma_Tmb = 0.20 +/1 0.06 K. For the (1,1) transition this sensitivity equates to a 3.2 kpc distance limit for detecting a 20 K, 400 Msun cloud at the 5-sigma level. Similar clouds of mass 5,000 Msun would be detected as far as the Galactic centre, while 30,000 Msun clouds would be seen across the Galaxy. We have developed an automatic emission finding procedure based on the ATNF DUCHAMP software and have used it to create a new catalogue of 669 dense molecular clouds. The catalogue is 100 percent complete at the 5-sigma detection limit (Tmb = 1.0 K). A preliminary analysis of the ensemble cloud properties suggest that the near kinematic distances are favoured. The cloud positions are consistent with current models of the Galaxy containing a long bar. Combined with other Galactic plane surveys this new molecular-line dataset constitutes a key tool for examining Galactic structure and evolution. Data-cubes, spectra and catalogues are available to the community via the HOPS website., Comment: 22 pages, 19 figures. Accepted for publication in MNRAS (25-July-2012)

Published
2012
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24. MAGMO: Coherent magnetic fields in the star forming regions of the Carina-Sagittarius spiral arm tangent

Author

Green, J. A., McClure-Griffiths, N. M., Caswell, J. L., Robishaw, T., and Harvey-Smith, L.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present the pilot results of the `MAGMO' project, targeted observations of ground-state hydroxyl masers towards sites of 6.7-GHz methanol maser emission in the Carina-Sagittarius spiral arm tangent, Galactic longitudes 280 degrees to 295 degrees. The `MAGMO' project aims to determine if Galactic magnetic fields can be traced with Zeeman splitting of masers associated with star formation. Pilot observations of 23 sites of methanol maser emission were made, with the detection of ground-state hydroxyl masers towards 11 of these and six additional offset sites. Of these 17 sites, nine are new detections of sites of 1665-MHz maser emission, three of them accompanied by 1667-MHz emission. More than 70% of the maser features have significant circular polarization, whilst only ~10% have significant linear polarization (although some features with up to 100% linear polarization are found). We find 11 Zeeman pairs across six sites of high-mass star formation with implied magnetic field strengths between -1.5 mG and +3.8 mG and a median field strength of +1.6 mG. Our measurements of Zeeman splitting imply that a coherent field orientation is experienced by the maser sites across a distance of 5.3+/-2.0 kpc within the Carina-Sagittarius spiral arm tangent., Comment: 19 pages, 13 figures, accepted for publication in MNRAS

Published
2012
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25. Complex Faraday depth structure of Active Galactic Nuclei as revealed by broadband radio polarimetry

Author

O'Sullivan, S. P., Brown, S., Robishaw, T., Schnitzeler, D. H. F. M., McClure-Griffiths, N. M., Feain, I. J., Taylor, A. R., Gaensler, B. M., Landecker, T. L., Harvey-Smith, L., and Carretti, E.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present a detailed study of the Faraday depth structure of four bright (> 1 Jy), strongly polarized, unresolved, radio-loud quasars. The Australia Telescope Compact Array (ATCA) was used to observe these sources with 2 GHz of instantaneous bandwidth from 1.1 to 3.1 GHz. This allowed us to spectrally resolve the polarization structure of spatially unresolved radio sources, and by fitting various Faraday rotation models to the data, we conclusively demonstrate that two of the sources cannot be described by a simple rotation measure (RM) component modified by depolarization from a foreground Faraday screen. Our results have important implications for using background extragalactic radio sources as probes of the Galactic and intergalactic magneto-ionic media as we show how RM estimations from narrow-bandwidth observations can give erroneous results in the presence of multiple interfering Faraday components. We postulate that the additional RM components arise from polarized structure in the compact inner regions of the radio source itself and not from polarized emission from Galactic or intergalactic foreground regions. We further suggest that this may contribute significantly to any RM time-variability seen in RM studies on these angular scales. Follow-up, high-sensitivity VLBI observations of these sources will directly test our predictions., Comment: Accepted for publication in MNRAS. 19 pages, 15 figures, 4 tables

Published
2012
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26. Very High Angular Resolution Science with the Square Kilometre Array

Author

Godfrey, L. E. H., Bignall, H., Tingay, S., Harvey-Smith, L., Kramer, M., Burke-Spolaor, S., Miller-Jones, J. C. A., Johnston-Hollitt, M., Ekers, R., and Gulyaev, S.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Preliminary specifications for the Square Kilometre Array (SKA) call for 25% of the total collecting area of the dish array to be located at distances greater than 180 km from the core, with a maximum baseline of at least 3000 km. The array will provide angular resolution ~ 40 - 2 mas at 0.5 - 10 GHz with image sensitivity reaching < 50 nJy/beam in an 8 hour integration with 500 MHz bandwidth. Given these specifications, the high angular resolution component of the SKA will be capable of detecting brightness temperatures < 200 K with milliarcsecond-scale angular resolution. The aim of this article is to bring together in one place a discussion of the broad range of new and important high angular resolution science that will be enabled by the SKA, and in doing so, address the merits of long baselines as part of the SKA. We highlight the fact that high angular resolution requiring baselines greater than 1000 km provides a rich science case with projects from many areas of astrophysics, including important contributions to key SKA science., Comment: 13 pages, 6 figures

Published
2011
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27. An improved map of the Galactic Faraday sky

Author

Oppermann, N., Junklewitz, H., Robbers, G., Bell, M. R., Enßlin, T. A., Bonafede, A., Braun, R., Brown, J. C., Clarke, T. E., Feain, I. J., Gaensler, B. M., Hammond, A., Harvey-Smith, L., Heald, G., Johnston-Hollitt, M., Klein, U., Kronberg, P. P., Mao, S. A., McClure-Griffiths, N. M., O'Sullivan, S. P., Pratley, L., Robishaw, T., Roy, S., Schnitzeler, D. H. F. M., Sotomayor-Beltran, C., Stevens, J., Stil, J. M., Sunstrum, C., Tanna, A., Taylor, A. R., and Van Eck, C. L.

Subjects
Astrophysics - Galaxy Astrophysics
Abstract

We aim to summarize the current state of knowledge regarding Galactic Faraday rotation in an all-sky map of the Galactic Faraday depth. For this we have assembled the most extensive catalog of Faraday rotation data of compact extragalactic polarized radio sources to date. In the map making procedure we use a recently developed algorithm that reconstructs the map and the power spectrum of a statistically isotropic and homogeneous field while taking into account uncertainties in the noise statistics. This procedure is able to identify some rotation angles that are offset by an integer multiple of pi. The resulting map can be seen as an improved version of earlier such maps and is made publicly available, along with a map of its uncertainty. For the angular power spectrum we find a power law behavior with a power law index of -2.14 for a Faraday sky where an overall variance profile as a function of Galactic latitude has been removed, in agreement with earlier work. We show that this is in accordance with a 3D Fourier power spectrum P(k) proportional to k^-2.14 of the underlying field n_e times B_r under simplifying geometrical and statistical assumptions., Comment: 16 pages, 11 figures. Update in one data catalog. All results are available at http://www.mpa-garching.mpg.de/ift/faraday/

Published
2011
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28. The H_2O southern Galactic Plane Survey (HOPS): I. Techniques and H_2O maser data

Author

Walsh, A. J., Breen, S. L., Britton, T., Brooks, K. J., Burton, M. G., Cunningham, M. R., Green, J. A., Harvey-Smith, L., Hindson, L., Hoare, M. G., Indermuehle, B., Jones, P. A., Lo, N., Longmore, S. N., Lowe, V., Phillips, C. J., Purcell, C. R., Thompson, M. A., Urquhart, J. S., Voronkov, M. A., White, G. L., and Whiting, M. T.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present first results of the H_2O Southern Galactic Plane Survey (HOPS), using the Mopra radiotelescope with a broad band backend and a beam size of about 2'. We have observed 100 square degrees of the southern Galactic plane at 12mm (19.5 to 27.5GHz), including spectral line emission from water masers, multiple metastable transitions of ammonia, cyanoacetylene, methanol and radio recombination lines. In this paper, we report on the characteristics of the survey and water maser emission. We find 540 water masers, of which 334 are new detections. The strongest maser is 3933Jy and the weakest is 0.7Jy, with 62 masers over 100Jy. In 14 maser sites, the spread in velocity of the water maser emission exceeds 100km/s. In one region, the water maser velocities are separated by 351.3km/s. The rms noise levels are typically between 1-2Jy, with 95% of the survey under 2Jy. We estimate completeness limits of 98% at around 8.4Jy and 50% at around 5.5Jy. We estimate that there are between 800 and 1500 water masers in the Galaxy that are detectable in a survey with similar completeness limits to HOPS. We report possible masers in NH_3 (11,9) and (8,6) emission towards G19.61-0.23 and in the NH_3 (3,3) line towards G23.33-0.30., Comment: accepted for publication in MNRAS

Published
2011
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29. Spectropolarimetry with the Allen Telescope Array: Faraday Rotation toward Bright Polarized Radio Galaxies

Author

Law, C. J., Gaensler, B. M., Bower, G. C., Backer, D. C., Bauermeister, A., Croft, S., Forster, R., Gutierrez-Kraybill, C., Harvey-Smith, L., Heiles, C., Hull, C., Keating, G., MacMahon, D., Whysong, D., Williams, P. K. G., and Wright, M.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We have observed 37 bright, polarized radio sources with the Allen Telescope Array (ATA) to present a novel analysis of their Faraday rotation properties. Each source was observed during the commissioning phase with 2 to 4 100-MHz bands at frequencies ranging from 1 to 2 GHz. These observations demonstrate how the continuous frequency coverage of the ATA's log-periodic receiver can be applied to the study of Faraday rotation measures (RMs). We use RM synthesis to show that wide-bandwidth data can find multiple RM components toward a single source. Roughly a quarter of the sources studied have extra RM components with high confidence (brighter than ~40 mJy), when observing with a RM resolution of roughly 100 rad/m2. These extra components contribute 10%-70% of the total polarized flux. This is the first time multiple RM components have been identified in a large sample of point sources. For our observing configuration, these extra RM components bias the measurement of the peak RM by 10-15 rad/m2 ; more generally, the peak RM cannot be determined more precisely than the RM beam size. Comparing our 1-2 GHz RM spectra to VLBA polarimetric maps shows both techniques can identify complicated Faraday structures in the sources. However, the RM values and fractional polarization are generally smaller at lower frequencies than in the higher-frequency VLBA maps. With a few exceptions, the RMs from this work are consistent with that of earlier, narrow-bandwidth, all-sky surveys. This work also describes the polarimetry calibration procedure and that on-axis ATA observations of linear polarization can be calibrated to an accuracy of 0.2% of Stokes I. Future research directions include studying the time-dependent RM structure in Active Galactic Nuclei (AGNs) and enabling accurate, wide-area RM surveys to test models of Galactic and extragalactic magnetic fields., Comment: Accepted to ApJ, 83 (preprint format) pages, 49 figures

Published
2010
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30. Faraday rotation of the supernova remnant G296.5+10.0: Evidence for a Magnetized Progenitor Wind

Author

Harvey-Smith, L., Gaensler, B. M., Kothes, R., Townsend, R., Heald, G. H., Ng, C. -Y., and Green, A. J.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present spectropolarimetric radio images of the supernova remnant (SNR) G296.5+10.0 at frequencies near 1.4 GHz, observed with the Australia Telescope Compact Array. By applying rotation measure (RM) synthesis to the data, a pixel-by-pixel map of Faraday rotation has been produced for the entire remnant. We find G296.5+10.0 to have a highly ordered RM structure, with mainly positive RMs (mean RM of +28 rad/m**2) on the eastern side and negative RMs (mean RM of -14 rad/m**2) on the western side, indicating a magnetic field which is directed away from us on one side and toward us on the other. We consider several possible mechanisms for creating the observed RM pattern. Neither Faraday rotation in foreground interstellar gas nor in a homogeneous ambient medium swept up by the SNR shell can easily explain the magnitude and sign of the observed RM pattern. Instead, we propose that the observed RMs are the imprint of an azimuthal magnetic field in the stellar wind of the progenitor star. Specifically, we calculate that a swept-up magnetized wind from a red supergiant can produce RMs of the observed magnitude, while the azimuthal pattern of the magnetic field at large distances from the star naturally produces the anti-symmetric RM pattern observed. Expansion into such a wind can possibly also account for the striking bilateral symmetry of the SNR's radio and X-ray morphologies., Comment: Accepted for publication in The Astrophysical Journal

Published
2010
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31. Spectropolarimetry of SNR G296.5+10.0

Author

Harvey-Smith, L., Gaensler, B. M., Ng, C. -Y., and Green, A. J

Subjects
Astrophysics
Abstract

Radio continuum emission from the supernova remnant G296.5+10.0 was observed using the Australia Telescope Compact Array. Using a 104 MHz bandwidth split into 13 x 8 MHz spectral channels, it was possible to produce a pixel-by-pixel image of Rotation Measure (RM) across the entire remnant. A lack of correlation between RM and X-ray surface brightness reveals that the RMs originate from outside the remnant. Using this information, we will characterise the smooth component of the magnetic field within the supernova remnant and attempt to probe the magneto-ionic structure and turbulent scale sizes in the ISM and galactic halo along the line-of-sight., Comment: IAU Symposium 259, Cosmic Magnetic Fields: From Planets, to Stars and Galaxies

Published
2008
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32. First images of 6.7-GHz methanol masers in DR21(OH) and DR21(OH)N

Author

Harvey-Smith, L., Soria-Ruiz, R., Duarte-Cabral, A., and Cohen, R. J.

Subjects
Astrophysics
Abstract

The first images of 6.7-GHz methanol masers in the massive star-forming regions DR21(OH) and DR21(OH)N are presented. By measuring the shapes, radial velocities and polarization properties of these masers it is possible to map out the structure, kinematics and magnetic fields in the molecular gas that surrounds newly-formed massive stars. The intrinsic angular resolution of the observations was 43 mas (~100 AU at the distance of DR21), but structures far smaller than this were revealed by employing a non-standard mapping technique. This technique was used in an attempt to identify the physical structure (e.g. disc, outflow, shock) associated with the methanol masers. Two distinct star-forming centres were identified. In DR21(OH) the masers had a linear morphology, and the individual maser spots each displayed an internal velocity gradient in the same direction as the large-scale structure. They were detected at the same position as the OH 1.7-GHz ground-state masers, close to the centre of an outflow traced by CO and class I methanol masers. The shape and velocity gradients of the masers suggests that they probably delineate a shock. In DR21(OH)N the methanol masers trace an arc with a double-peaked profile and a complex velocity gradient. This velocity gradient closely resembles that of a Keplerian disc. The masers in the arc are 4.5% linearly polarized, with a polarization angle that indicates that the magnetic field direction is roughly perpendicular to the large-scale magnetic field in the region (indicated by lower angular resolution measurements of the CO and dust polarization). The suitability of channel-by-channel centroid mapping is discussed as an improved and viable means to maximise the information gained from the data., Comment: Accepted by MNRAS

Published
2007
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33. Methanol Maser Polarization in W3(OH)

Author

Vlemmings, W. H. T., Harvey-Smith, L., and Cohen, R. J.

Subjects
Astrophysics
Abstract

We present the first 6.7 GHz methanol maser linear polarization map of the extended filamentary maser structure around the compact HII region W3(OH). The methanol masers show linear polarization up to 8 per cent and the polarization angles indicate a magnetic field direction along the North-South maser structure. The polarization angles are consistent with those measured for the OH masers, taking into account external Faraday rotation toward W3(OH), and confirm that the OH and methanol masers are found in similar physical conditions. Additionally we discuss the Zeeman splitting of the 6.7 GHz methanol transition and present an upper limit of ~22 mG for the magnetic field strength in the maser region. The upper limit is fully consistent with the field strengths derived from OH maser Zeeman splitting., Comment: 5 pages, 2 figures, accepted for publication in MNRAS

Published
2006
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34. The Rapid ASKAP Continuum Survey III: Spectra and Polarisation In Cutouts of Extragalactic Sources (SPICE-RACS) first data release

Author

Thomson, A.J.M., McConnell, D., Lenc, E., Galvin, T.J., Rudnick, L., Heald, G., Hale, C.L., Duchesne, S.W., Anderson, C.S, Carretti, E., Federrath, C., Gaensler, B.M., Harvey-Smith, L., Haverkorn, M., Hotan, A.W., Ki Ma, Y., Murphy, T., McClure-Griffiths, N.M., Moss, V.A., O’Sullivan, S.P., Raja, W., Seta, A., Eck, C.L. Van, West, J.L., Whiting, M.T., Wieringa, M.H., Thomson, A.J.M., McConnell, D., Lenc, E., Galvin, T.J., Rudnick, L., Heald, G., Hale, C.L., Duchesne, S.W., Anderson, C.S, Carretti, E., Federrath, C., Gaensler, B.M., Harvey-Smith, L., Haverkorn, M., Hotan, A.W., Ki Ma, Y., Murphy, T., McClure-Griffiths, N.M., Moss, V.A., O’Sullivan, S.P., Raja, W., Seta, A., Eck, C.L. Van, West, J.L., Whiting, M.T., and Wieringa, M.H.

Abstract

Contains fulltext : 296442.pdf (Publisher’s version ) (Open Access)

Published
2023

35. GASKAP-HI pilot survey science I: ASKAP zoom observations of Hi emission in the Small Magellanic Cloud

Author

Pingel, NM, Dempsey, J, McClure-Griffiths, NM, Dickey, JM, Jameson, KE, Arce, H, Anglada, G, Bland-Hawthorn, J, Breen, SL, Buckland-Willis, F, Clark, SE, Dawson, JR, Dénes, H, Di Teodoro, EM, For, BQ, Foster, TJ, Gómez, JF, Imai, H, Joncas, G, Kim, CG, Lee, MY, Lynn, C, Leahy, D, Ma, YK, Marchal, A, McConnell, D, Miville-Deschènes, MA, Moss, VA, Murray, CE, Nidever, D, Peek, J, Stanimirović, S, Staveley-Smith, L, Tepper-Garcia, T, Tremblay, CD, Uscanga, L, Van Loon, JT, Vázquez-Semadeni, E, Allison, JR, Anderson, CS, Ball, L, Bell, M, Bock, DCJ, Bunton, J, Cooray, FR, Cornwell, T, Koribalski, BS, Gupta, N, Hayman, DB, Harvey-Smith, L, Lee-Waddell, K, Ng, A, Phillips, CJ, Voronkov, M, Westmeier, T, Whiting, MT, Pingel, NM, Dempsey, J, McClure-Griffiths, NM, Dickey, JM, Jameson, KE, Arce, H, Anglada, G, Bland-Hawthorn, J, Breen, SL, Buckland-Willis, F, Clark, SE, Dawson, JR, Dénes, H, Di Teodoro, EM, For, BQ, Foster, TJ, Gómez, JF, Imai, H, Joncas, G, Kim, CG, Lee, MY, Lynn, C, Leahy, D, Ma, YK, Marchal, A, McConnell, D, Miville-Deschènes, MA, Moss, VA, Murray, CE, Nidever, D, Peek, J, Stanimirović, S, Staveley-Smith, L, Tepper-Garcia, T, Tremblay, CD, Uscanga, L, Van Loon, JT, Vázquez-Semadeni, E, Allison, JR, Anderson, CS, Ball, L, Bell, M, Bock, DCJ, Bunton, J, Cooray, FR, Cornwell, T, Koribalski, BS, Gupta, N, Hayman, DB, Harvey-Smith, L, Lee-Waddell, K, Ng, A, Phillips, CJ, Voronkov, M, Westmeier, T, and Whiting, MT

Abstract

We present the most sensitive and detailed view of the neutral hydrogen emission associated with the Small Magellanic Cloud (SMC), through the combination of data from the Australian Square Kilometre Array Pathfinder (ASKAP) and Parkes (Murriyang), as part of the Galactic Australian Square Kilometre Array Pathfinder (GASKAP) pilot survey. These GASKAP-HI pilot observations, for the first time, reveal in the SMC on similar physical scales as other important tracers of the interstellar medium, such as molecular gas and dust. The resultant image cube possesses an rms noise level of 1.1 K spectral channel with an angular resolution of . We discuss the calibration scheme and the custom imaging pipeline that utilises a joint deconvolution approach, efficiently distributed across a computing cluster, to accurately recover the emission extending across the entire field-of-view. We provide an overview of the data products and characterise several aspects including the noise properties as a function of angular resolution and the represented spatial scales by deriving the global transfer function over the full spectral range. A preliminary spatial power spectrum analysis on individual spectral channels reveals that the power law nature of the density distribution extends down to scales of 10 pc. We highlight the scientific potential of these data by comparing the properties of an outflowing high-velocity cloud with previous ASKAP+Parkes test observations.

Published
2022

36. H i absorption at z ∼ 0.7 against the lobe of the powerful radio galaxy PKS 0409−75

Author

Mahony, EK, Allison, JR, Sadler, EM, Ellison, SL, Mao, SA, Morganti, R, Moss, VA, Seta, A, Tadhunter, CN, Weng, S, Whiting, MT, Yoon, H, Bell, M, Bunton, JD, Harvey-Smith, L, Kimball, A, Koribalski, BS, and Voronkov, MA

Subjects
0201 Astronomical and Space Sciences, Astronomy & Astrophysics
Abstract

We present results from a search for the H I 21-cm line in absorption towards 16 bright radio sources with the six-antenna commissioning array of the Australian Square Kilometre Array Pathfinder. Our targets were selected from the 2-Jy sample, a flux-limited survey of the southern radio sky with extensive multiwavelength follow-up. Two sources were detected in H I absorption including a new detection towards the bright Fanaroff–Riley Type II radio galaxy PKS 0409−75 at a redshift of z = 0.674. The H I absorption line is blueshifted by ∼3300 km s−1 compared to the optical redshift of the host galaxy of PKS 0409−75 at z = 0.693. Deep optical imaging and spectroscopic follow-up with the GMOS instrument on the Gemini-South telescope reveal that the H I absorption is associated with a galaxy in front of the southern radio lobe with a stellar mass of 3.2–6.8 × 1011 M, a star formation rate of ∼1.24 M yr−1, and an estimated H I column density of 2.16 × 1021 cm−2, assuming a spin temperature of Tspin = 500 K and source covering factor of Cf = 0.3. Using polarization measurements of PKS 0409−75 from the literature, we estimate the magnetic field of the absorbing galaxy to be ∼14.5 μG, consistent with field strengths observed in nearby spiral galaxies but larger than expected for an elliptical galaxy. Results from this pilot study can inform future surveys as new wide-field telescopes allow us to search for 21-cm H I absorption towards all bright radio sources as opposed to smaller targeted samples.

Published
2022

37. GASKAP-HI pilot survey science I: ASKAP zoom observations of Hi emission in the Small Magellanic Cloud

Author

Pingel, N. M., primary, Dempsey, J., additional, McClure-Griffiths, N. M., additional, Dickey, J. M., additional, Jameson, K. E., additional, Arce, H., additional, Anglada, G., additional, Bland-Hawthorn, J., additional, Breen, S. L., additional, Buckland-Willis, F., additional, Clark, S. E., additional, Dawson, J. R., additional, Dénes, H., additional, Di Teodoro, E. M., additional, For, B.-Q., additional, Foster, Tyler J., additional, Gómez, J. F., additional, Imai, H., additional, Joncas, G., additional, Kim, C.-G., additional, Lee, M.-Y., additional, Lynn, C., additional, Leahy, D., additional, Ma, Y. K., additional, Marchal, A., additional, McConnell, D., additional, Miville-Deschènes, M.-A., additional, Moss, V. A., additional, Murray, C. E., additional, Nidever, D., additional, Peek, J., additional, Stanimirović, S., additional, Staveley-Smith, L., additional, Tepper-Garcia, T., additional, Tremblay, C. D., additional, Uscanga, L., additional, van Loon, J. Th., additional, Vázquez-Semadeni, E., additional, Allison, J. R., additional, Anderson, C. S., additional, Ball, Lewis, additional, Bell, M., additional, Bock, D. C.-J., additional, Bunton, J., additional, Cooray, F. R., additional, Cornwell, T., additional, Koribalski, B. S., additional, Gupta, N., additional, Hayman, D. B., additional, Harvey-Smith, L., additional, Lee-Waddell, K., additional, Ng, A., additional, Phillips, C. J., additional, Voronkov, M., additional, Westmeier, T., additional, and Whiting, M. T., additional

Published
2022
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38. Radio observations of supernova remnant G1.9+0.3

Author

Luken, KJ, Filipović, MD, Maxted, NI, Kothes, R, Norris, RP, Allison, JR, Blackwell, R, Braiding, C, Brose, R, Burton, M, de Horta, AY, Galvin, TJ, Harvey-Smith, L, Hurley-Walker, N, Leahy, D, Ralph, NO, Roper, Q, Rowell, G, Sushch, I, Urošević, D, Wong, GF, Luken, KJ, Filipović, MD, Maxted, NI, Kothes, R, Norris, RP, Allison, JR, Blackwell, R, Braiding, C, Brose, R, Burton, M, de Horta, AY, Galvin, TJ, Harvey-Smith, L, Hurley-Walker, N, Leahy, D, Ralph, NO, Roper, Q, Rowell, G, Sushch, I, Urošević, D, and Wong, GF

Abstract

We present 1-10 GHz radio continuum flux density, spectral index, polarization, and rotation measure (RM) images of the youngest known Galactic supernova remnant (SNR) G1.9+0.3, using observations from the Australia Telescope Compact Array. We have conducted an expansion study spanning eight epochs between 1984 and 2017, yielding results consistent with previous expansion studies of G1.9+0.3. We find a mean radio continuum expansion rate of (0.78 ± 0.09) per cent yr−1 (or ∼8900 km s−1 at an assumed distance of 8.5 kpc), although the expansion rate varies across the SNR perimetre. In the case of the most recent epoch between 2016 and 2017, we observe faster-than-expected expansion of the northern region. We find a global spectral index for G1.9+0.3 of −0.81 ± 0.02 (76 MHz-10 GHz). Towards the northern region, however, the radio spectrum is observed to steepen significantly (∼−1). Towards the two so-called (east and west) 'ears' of G1.9+0.3, we find very different RM values of 400-600 and 100-200 rad m2, respectively. The fractional polarization of the radio continuum emission reaches (19 ± 2) per cent, consistent with other, slightly older, SNRs such as Cas A.

Published
2020

39. Field sources near the southern-sky calibrator PKS B1934-638: Effect on spectral line observations with SKA-MID and its precursors

Author

Heywood, I, Lenc, E, Serra, P, Hugo, B, Bannister, KW, Bell, ME, Chippendale, A, Harvey-Smith, L, Marvil, J, Mcconnell, D, Voronkov, MA, Heywood, I, Lenc, E, Serra, P, Hugo, B, Bannister, KW, Bell, ME, Chippendale, A, Harvey-Smith, L, Marvil, J, Mcconnell, D, and Voronkov, MA

Abstract

© 2020 The Author(s). Accurate instrumental bandpass corrections are essential for the reliable interpretation of spectral lines from targeted and survey-mode observations with radio interferometers. Bandpass correction is typically performed by comparing measurements of a strong calibrator source to an assumed model, typically an isolated point source. The wide field-of-view and high sensitivity of modern interferometers means that additional sources are often detected in observations of calibrators. This can introduce errors into bandpass corrections and subsequently the target data if not properly accounted for. Focusing on the standard calibrator PKS B1934-638, we perform simulations to asses this effect by constructing a wide-field sky model. The cases of ASKAP (0.7-1.9 GHz), MeerKAT (UHF: 0.58-1.05 GHz; L-band: 0.87-1.67 GHz) and Band 2 (0.95-1.76 GHz) of SKA-MID are examined. The use of a central point source model during bandpass calibration is found to impart amplitude errors into spectra measured by the precursor instruments at the ∼0.2-0.5 per cent level dropping to ∼0.01 per cent in the case of SKA-MID. This manifests itself as ripples in the source spectrum, the behaviour of which is coupled to the distribution of the array baselines, the solution interval, the primary beam size, the hour-angle of the calibration scan, as well as the weights used when imaging the target. Calibration pipelines should routinely employ complete field models for standard calibrators to remove this potentially destructive contaminant from the data, a recommendation we validate by comparing our simulation results to a MeerKAT scan of PKS B1934-638, calibrated with and without our expanded sky model.

Published
2020

40. Early Science from POSSUM: Shocks, turbulence, and a massive new reservoir of ionised gas in the Fornax cluster

Author

Anderson, C. S., primary, Heald, G. H., additional, Eilek, J. A., additional, Lenc, E., additional, Gaensler, B. M., additional, Rudnick, Lawrence, additional, Van Eck, C. L., additional, O’Sullivan, S. P., additional, Stil, J. M., additional, Chippendale, A., additional, Riseley, C. J., additional, Carretti, E., additional, West, J., additional, Farnes, J., additional, Harvey-Smith, L., additional, McClure-Griffiths, N. M., additional, Bock, Douglas C. J., additional, Bunton, J. D., additional, Koribalski, B., additional, Tremblay, C. D., additional, Voronkov, M. A., additional, and Warhurst, K., additional

Published
2021
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41. Australian square kilometre array pathfinder: I. system description

Author

Hotan, A. W., primary, Bunton, J. D., additional, Chippendale, A. P., additional, Whiting, M., additional, Tuthill, J., additional, Moss, V. A., additional, McConnell, D., additional, Amy, S. W., additional, Huynh, M. T., additional, Allison, J. R., additional, Anderson, C. S., additional, Bannister, K. W., additional, Bastholm, E., additional, Beresford, R., additional, Bock, D. C.-J., additional, Bolton, R., additional, Chapman, J. M., additional, Chow, K., additional, Collier, J. D., additional, Cooray, F. R., additional, Cornwell, T. J., additional, Diamond, P. J., additional, Edwards, P. G., additional, Feain, I. J., additional, Franzen, T. M. O., additional, George, D., additional, Gupta, N., additional, Hampson, G. A., additional, Harvey-Smith, L., additional, Hayman, D. B., additional, Heywood, I., additional, Jacka, C., additional, Jackson, C. A., additional, Jackson, S., additional, Jeganathan, K., additional, Johnston, S., additional, Kesteven, M., additional, Kleiner, D., additional, Koribalski, B. S., additional, Lee-Waddell, K., additional, Lenc, E., additional, Lensson, E. S., additional, Mackay, S., additional, Mahony, E. K., additional, McClure-Griffiths, N. M., additional, McConigley, R., additional, Mirtschin, P., additional, Ng, A. K., additional, Norris, R. P., additional, Pearce, S. E., additional, Phillips, C., additional, Pilawa, M. A., additional, Raja, W., additional, Reynolds, J. E., additional, Roberts, P., additional, Roxby, D. N., additional, Sadler, E. M., additional, Shields, M., additional, Schinckel, A. E. T., additional, Serra, P., additional, Shaw, R. D., additional, Sweetnam, T., additional, Troup, E. R., additional, Tzioumis, A., additional, Voronkov, M. A., additional, and Westmeier, T., additional

Published
2021
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44. SCUBA-2 Continuum Observations of Pre-protostellar Evolution - survey description and compact source catalogue

Author

Eden, D. J., Liu, Tie, Kim, Kee-Tae, Juvela, M., Liu, S. -Y., Tatematsu, K., Di Francesco, J., Wang, K., Wu, Y., Thompson, M. A., Fuller, G. A., Li, Di, Ristorcelli, I., Kang, Sung-ju, Hirano, N., Johnstone, D., Lin, Y., He, J. H., Koch, P. M., Sanhueza, Patricio, Qin, S. -L., Zhang, Q., Goldsmith, P. F., Evans, N. J., Yuan, J., Zhang, C. -P., White, G. J., Choi, Minho, Lee, Chang Won, Toth, L. V., Mairs, S., Yi, H. -W., Tang, M., Soam, A., Peretto, N., Samal, M. R., Fich, M., Parsons, H., Malinen, J., Bendo, G. J., Rivera-Ingraham, A., Liu, H. -L., Wouterloot, J., Li, P. S., Qian, L., Rawlings, J., Rawlings, M. G., Feng, S., Wang, B., Li, Dalei, Liu, M., Luo, G., Marston, A. P., Pattle, K. M., Pelkonen, V. -M., Rigby, A. J., Zahorecz, S., Zhang, G., Bogner, R., Aikawa, Y., Akhter, S., Alina, D., Bell, G., Bernard, J. -P., Blain, A., Bronfman, L., Byun, D. -Y., Chapman, S., Chen, H. -R., Chen, M., Chen, W. -P., Chen, X., Chen, Xuepeng, Chrysostomou, A., Chu, Y. -H., Chung, E. J., Cornu, D., Cosentino, G., Cunningham, M. R., Demyk, K., Drabek-Maunder, E., Doi, Y., Eswaraiah, C., Falgarone, E., Feher, O., Fraser, H., Friberg, P., Garay, G., Ge, J. X., Gear, W. K., Greaves, J., Guan, X., Harvey-Smith, L., Hasegawa, T., He, Y., Henkel, C., Hirota, T., Holland, W., Hughes, A., Jarken, E., Ji, T. -G., Jimenez-Serra, I., Kang, M., Kawabata, K. S., Kim, Gwanjeong, Kim, Jungha, Kim, Jongsoo, Kim, S., Koo, B. -C., Kwon, Woojin, Kuan, Y. -J., Lacaille, K. M., Lai, S. -P., Lee, C. F., Lee, J. -E., Lee, Y. -U., Li, H., Lo, N., Lopez, J. A. P., Lu, X., Lyo, A. -R., Mardones, D., McGehee, P., Meng, F., Montier, L., Montillaud, J., Moore, T. J. T., Morata, O., Moriarty-Schieven, G. H., Ohashi, S., Pak, S., Park, Geumsook, Paladini, R., Pech, G., Qiu, K., Ren, Z. -Y., Richer, J., Sakai, T., Shang, H., Shinnaga, H., Stamatellos, D., Tang, Y. -W., Traficante, A., Vastel, C., Viti, S., Walsh, A., Wang, H., Wang, J., Ward-Thompson, D., Whitworth, A., Wilson, C. D., Xu, Y., Yang, J., Yuan, Y. -L., Yuan, L., Zavagno, A., Zhang, C., Zhang, H. -W., Zhou, C., Zhou, J., Zhu, L., Zuo, P., University of Helsinki, Department of Physics, and University of Helsinki, Particle Physics and Astrophysics

Subjects
LEGACY SURVEY, stars: formation, ATLASGAL, SPIRAL ARMS, 115 Astronomy, Space science, ISM: clouds, CLOUD, STAR-FORMATION, submillimetre: ISM, CLUMP IDENTIFICATION, surveys, GAS, MILKY-WAY, COMPLETE SAMPLE, GOULD BELT SURVEY
Abstract

We present the first release of the data and compact-source catalogue for the JCMT Large Program SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE). SCOPE consists of 850 mu m continuum observations of 1235 Planck Galactic Cold Clumps (PGCCs) made with the Submillimetre Common-User Bolometer Array 2 on the James Clerk Maxwell Telescope. These data are at an angular resolution of 14.4 arcsec, significantly improving upon the 353 GHz resolution of Planck at 5 arcmin, and allowing for a catalogue of 3528 compact sources in 558 PGCCs. We find that the detected PGCCs have significant sub-structure, with 61 per cent of detected PGCCs having three or more compact sources, with filamentary structure also prevalent within the sample. A detection rate of 45 per cent is found across the survey, which is 95 per cent complete to Planck column densities of N-H2 > 5 x10(21) cm(-2). By positionally associating the SCOPE compact sources with young stellar objects, the star formation efficiency, as measured by the ratio of luminosity to mass, in nearby clouds is found to be similar to that in the more distant Galactic Plane, with the column density distributions also indistinguishable from each other.

Published
2019

45. SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution – Survey Description and Compact Source Catalogue

Author

Eden, D J, Liu, Tie, Kim, Kee-Tae, Juvela, M, Liu, S -Y, Tatematsu, K, Di Francesco, J, Wang, K, Wu, Y, Thompson, M A, Fuller, G A, Li, Di, Ristorcelli, I, Kang, Sung-ju, Hirano, N, Johnstone, D, Lin, Y, He, J H, Koch, P M, Sanhueza, Patricio, Qin, S -L, Zhang, Q, Goldsmith, P F, Evans, N J, Yuan, J, Zhang, C -P, White, G J, Choi, Minho, Won Lee, Chang, Toth, L V, Mairs, S, Yi, H -W, Tang, M, Soam, A, Peretto, N, Samal, M R, Fich, M, Parsons, H, Malinen, J, Bendo, G J, Rivera-Ingraham, A, Liu, H -L, Wouterloot, J, Li, P S, Qian, L, Rawlings, J, Rawlings, M G, Feng, S, Wang, B, Li, Dalei, Liu, M, Luo, G, Marston, A P, Pattle, K M, Pelkonen, V -M, Rigby, A J, Zahorecz, S, Zhang, G, Bőgner, R, Aikawa, Y, Akhter, S, Alina, D, Bell, G, Bernard, J -P, Blain, A, Bronfman, L, Byun, D -Y, Chapman, S, Chen, H -R, Chen, M, Chen, W -P, Chen, X, Chen, Xuepeng, Chrysostomou, A, Chu, Y -H, Chung, E J, Cornu, D, Cosentino, G, Cunningham, M R, Demyk, K, Drabek-Maunder, E, Doi, Y, Eswaraiah, C, Falgarone, E, Fehér, O, Fraser, H, Friberg, P, Garay, G, Ge, J X, Gear, W K, Greaves, J, Guan, X, Harvey-Smith, L, Hasegawa, T, He, Y, Henkel, C, Hirota, T, Holland, W, Hughes, A, Jarken, E, Ji, T -G, Jimenez-Serra, I, Kang, Miju, Kawabata, K S, Kim, Gwanjeong, Kim, Jungha, Kim, Jongsoo, Kim, S, Koo, B -C, Kwon, Woojin, Kuan, Y -J, Lacaille, K M, Lai, S -P, Lee, C F, Lee, J -E, Lee, Y -U, Li, H, Lo, N, Lopez, J A P, Lu, X, Lyo, A -R, Mardones, D, McGehee, P, Meng, F, Montier, L, Montillaud, J, Moore, T J T, Morata, O, Moriarty-Schieven, G H, Ohashi, S, Pak, S, Park, Geumsook, Paladini, R, Pech, G, Qiu, K, Ren, Z -Y, Richer, J, Sakai, T, Shang, H, Shinnaga, H, Stamatellos, Dimitris, Tang, Y -W, Traficante, A, Vastel, C, Viti, S, Walsh, A, Wang, H, Wang, J, Ward-Thompson, Derek, Whitworth, A, Wilson, C D, Xu, Y, Yang, J, Yuan, Y -L, Yuan, L, Zavagno, A, Zhang, C, Zhang, H -W, Zhou, C, Zhou, J, Zhu, L, Zuo, P, Eden, D J, Liu, Tie, Kim, Kee-Tae, Juvela, M, Liu, S -Y, Tatematsu, K, Di Francesco, J, Wang, K, Wu, Y, Thompson, M A, Fuller, G A, Li, Di, Ristorcelli, I, Kang, Sung-ju, Hirano, N, Johnstone, D, Lin, Y, He, J H, Koch, P M, Sanhueza, Patricio, Qin, S -L, Zhang, Q, Goldsmith, P F, Evans, N J, Yuan, J, Zhang, C -P, White, G J, Choi, Minho, Won Lee, Chang, Toth, L V, Mairs, S, Yi, H -W, Tang, M, Soam, A, Peretto, N, Samal, M R, Fich, M, Parsons, H, Malinen, J, Bendo, G J, Rivera-Ingraham, A, Liu, H -L, Wouterloot, J, Li, P S, Qian, L, Rawlings, J, Rawlings, M G, Feng, S, Wang, B, Li, Dalei, Liu, M, Luo, G, Marston, A P, Pattle, K M, Pelkonen, V -M, Rigby, A J, Zahorecz, S, Zhang, G, Bőgner, R, Aikawa, Y, Akhter, S, Alina, D, Bell, G, Bernard, J -P, Blain, A, Bronfman, L, Byun, D -Y, Chapman, S, Chen, H -R, Chen, M, Chen, W -P, Chen, X, Chen, Xuepeng, Chrysostomou, A, Chu, Y -H, Chung, E J, Cornu, D, Cosentino, G, Cunningham, M R, Demyk, K, Drabek-Maunder, E, Doi, Y, Eswaraiah, C, Falgarone, E, Fehér, O, Fraser, H, Friberg, P, Garay, G, Ge, J X, Gear, W K, Greaves, J, Guan, X, Harvey-Smith, L, Hasegawa, T, He, Y, Henkel, C, Hirota, T, Holland, W, Hughes, A, Jarken, E, Ji, T -G, Jimenez-Serra, I, Kang, Miju, Kawabata, K S, Kim, Gwanjeong, Kim, Jungha, Kim, Jongsoo, Kim, S, Koo, B -C, Kwon, Woojin, Kuan, Y -J, Lacaille, K M, Lai, S -P, Lee, C F, Lee, J -E, Lee, Y -U, Li, H, Lo, N, Lopez, J A P, Lu, X, Lyo, A -R, Mardones, D, McGehee, P, Meng, F, Montier, L, Montillaud, J, Moore, T J T, Morata, O, Moriarty-Schieven, G H, Ohashi, S, Pak, S, Park, Geumsook, Paladini, R, Pech, G, Qiu, K, Ren, Z -Y, Richer, J, Sakai, T, Shang, H, Shinnaga, H, Stamatellos, Dimitris, Tang, Y -W, Traficante, A, Vastel, C, Viti, S, Walsh, A, Wang, H, Wang, J, Ward-Thompson, Derek, Whitworth, A, Wilson, C D, Xu, Y, Yang, J, Yuan, Y -L, Yuan, L, Zavagno, A, Zhang, C, Zhang, H -W, Zhou, C, Zhou, J, Zhu, L, and Zuo, P

Abstract

We present the first release of the data and compact-source catalogue for the JCMT Large Program SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE). SCOPE consists of 850-μm continuum observations of 1235 Planck Galactic Cold Clumps (PGCCs) made with the Submillimetre Common-User Bolometer Array 2 on the James Clerk Maxwell Telescope. These data are at an angular resolution of 14.4 arcsec, significantly improving upon the 353-GHz resolution of Planck at 5 arcmin, and allowing for a catalogue of 3528 compact sources in 558 PGCCs. We find that the detected PGCCs have significant sub-structure, with 61 per cent of detected PGCCs having 3 or more compact sources, with filamentary structure also prevalent within the sample. A detection rate of 45 per cent is found across the survey, which is 95 per cent complete to Planck column densities of N H 2 NH2 > 5 × 1021 cm−2. By positionally associating the SCOPE compact sources with YSOs, the star formation efficiency, as measured by the ratio of luminosity to mass, in nearby clouds is found to be similar to that in the more distant Galactic Plane, with the column density distributions also indistinguishable from each other.

Published
2019

46. ASKAP commissioning observations of the GAMA 23 field

Author

Leahy DA, Hopkins AM, Norris RP, Marvil J, Collier JD, Taylor EN, Allison JR, Anderson C, Bell M, Bilicki M, Bland-Hawthorn J, Brough S, Brown MJI, Driver S, Gurkan G, Harvey-Smith L, Heywood I, Holwerda BW, Liske J, Lopez-Sanchez AR, McConnell D, Moffett A, Owers MS, Pimbblet KA, Raja W, Seymour N, Voronkov MA, Wang L, Leahy DA, Hopkins AM, Norris RP, Marvil J, Collier JD, Taylor EN, Allison JR, Anderson C, Bell M, Bilicki M, Bland-Hawthorn J, Brough S, Brown MJI, Driver S, Gurkan G, Harvey-Smith L, Heywood I, Holwerda BW, Liske J, Lopez-Sanchez AR, McConnell D, Moffett A, Owers MS, Pimbblet KA, Raja W, Seymour N, Voronkov MA, and Wang L

Abstract

© Astronomical Society of Australia 2019. We have observed the G23 field of the Galaxy AndMass Assembly (GAMA) survey using the Australian Square Kilometre Array Pathfinder (ASKAP) in its commissioning phase to validate the performance of the telescope and to characterise the detected galaxy populations. This observation covers ∼48 deg2 with synthesised beam of 32.7 arcsec by 17.8 arcsec at 936MHz, and ∼39 deg2 with synthesised beam of 15.8 arcsec by 12.0 arcsec at 1320MHz. At both frequencies, the root-mean-square (r.m.s.) noise is ∼0.1 mJy/beam. We combine these radio observations with the GAMA galaxy data, which includes spectroscopy of galaxies that are i-band selected with a magnitude limit of 19.2. Wide-field Infrared Survey Explorer (WISE) infrared (IR) photometry is used to determine which galaxies host an active galactic nucleus (AGN). In properties including source counts, mass distributions, and IR versus radio luminosity relation, the ASKAP-detected radio sources behave as expected. Radio galaxies have higher stellar mass and luminosity in IR, optical, and UV than other galaxies. We apply optical and IR AGN diagnostics and find that they disagree for ∼30% of the galaxies in our sample. We suggest possible causes for the disagreement. Some cases can be explained by optical extinction of the AGN, but for more than half of the cases we do not find a clear explanation. Radio sources aremore likely (∼6%) to have an AGN than radio quiet galaxies (∼1%), but the majority of AGN are not detected in radio at this sensitivity.

Published
2019

47. SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution – survey description and compact source catalogue

Author

Eden, D J, primary, Liu, Tie, additional, Kim, Kee-Tae, additional, Juvela, M, additional, Liu, S-Y, additional, Tatematsu, K, additional, Francesco, J. Di, additional, Wang, K, additional, Wu, Y, additional, Thompson, M A, additional, Fuller, G A, additional, Li, Di, additional, Ristorcelli, I, additional, Kang, Sung-ju, additional, Hirano, N, additional, Johnstone, D, additional, Lin, Y, additional, He, J H, additional, Koch, P M, additional, Sanhueza, Patricio, additional, Qin, S-L, additional, Zhang, Q, additional, Goldsmith, P F, additional, Evans, N J, additional, Yuan, J, additional, Zhang, C-P, additional, White, G J, additional, Choi, Minho, additional, Lee, Chang Won, additional, Toth, L V, additional, Mairs, S, additional, Yi, H-W, additional, Tang, M, additional, Soam, A, additional, Peretto, N, additional, Samal, M R, additional, Fich, M, additional, Parsons, H, additional, Malinen, J, additional, Bendo, G J, additional, Rivera-Ingraham, A, additional, Liu, H-L, additional, Wouterloot, J, additional, Li, P S, additional, Qian, L, additional, Rawlings, J, additional, Rawlings, M G, additional, Feng, S, additional, Wang, B, additional, Li, Dalei, additional, Liu, M, additional, Luo, G, additional, Marston, A P, additional, Pattle, K M, additional, Pelkonen, V-M, additional, Rigby, A J, additional, Zahorecz, S, additional, Zhang, G, additional, Bőgner, R, additional, Aikawa, Y, additional, Akhter, S, additional, Alina, D, additional, Bell, G, additional, Bernard, J-P, additional, Blain, A, additional, Bronfman, L, additional, Byun, D-Y, additional, Chapman, S, additional, Chen, H-R, additional, Chen, M, additional, Chen, W-P, additional, Chen, X, additional, Chen, Xuepeng, additional, Chrysostomou, A, additional, Chu, Y-H, additional, Chung, E J, additional, Cornu, D, additional, Cosentino, G, additional, Cunningham, M R, additional, Demyk, K, additional, Drabek-Maunder, E, additional, Doi, Y, additional, Eswaraiah, C, additional, Falgarone, E, additional, Fehér, O, additional, Fraser, H, additional, Friberg, P, additional, Garay, G, additional, Ge, J X, additional, Gear, W K, additional, Greaves, J, additional, Guan, X, additional, Harvey-Smith, L, additional, Hasegawa, T, additional, He, Y, additional, Henkel, C, additional, Hirota, T, additional, Holland, W, additional, Hughes, A, additional, Jarken, E, additional, Ji, T-G, additional, Jimenez-Serra, I, additional, Kang, M, additional, Kawabata, K S, additional, Kim, Gwanjeong, additional, Kim, Jungha, additional, Kim, Jongsoo, additional, Kim, S, additional, Koo, B-C, additional, Kwon, Woojin, additional, Kuan, Y-J, additional, Lacaille, K M, additional, Lai, S-P, additional, Lee, C F, additional, Lee, J-E, additional, Lee, Y-U, additional, Li, H, additional, Lo, N, additional, Lopez, J A P, additional, Lu, X, additional, Lyo, A-R, additional, Mardones, D, additional, McGehee, P, additional, Meng, F, additional, Montier, L, additional, Montillaud, J, additional, Moore, T J T, additional, Morata, O, additional, Moriarty-Schieven, G H, additional, Ohashi, S, additional, Pak, S, additional, Park, Geumsook, additional, Paladini, R, additional, Pech, G, additional, Qiu, K, additional, Ren, Z-Y, additional, Richer, J, additional, Sakai, T, additional, Shang, H, additional, Shinnaga, H, additional, Stamatellos, D, additional, Tang, Y-W, additional, Traficante, A, additional, Vastel, C, additional, Viti, S, additional, Walsh, A, additional, Wang, H, additional, Wang, J, additional, Ward-Thompson, D, additional, Whitworth, A, additional, Wilson, C D, additional, Xu, Y, additional, Yang, J, additional, Yuan, Y-L, additional, Yuan, L, additional, Zavagno, A, additional, Zhang, C, additional, Zhang, H-W, additional, Zhou, C, additional, Zhou, J, additional, Zhu, L, additional, and Zuo, P, additional

Published
2019
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48. ASKAP commissioning observations of the GAMA 23 field

Author

Leahy, Denis A., primary, Hopkins, A. M., additional, Norris, R. P., additional, Marvil, J., additional, Collier, J. D., additional, Taylor, E. N., additional, Allison, J. R., additional, Anderson, C., additional, Bell, M., additional, Bilicki, M., additional, Bland-Hawthorn, J., additional, Brough, S., additional, Brown, M. J. I., additional, Driver, S., additional, Gurkan, G., additional, Harvey-Smith, L., additional, Heywood, I., additional, Holwerda, B. W., additional, Liske, J., additional, Lopez-Sanchez, A. R., additional, McConnell, D., additional, Moffett, A., additional, Owers, M. S., additional, Pimbblet, K. A., additional, Raja, W., additional, Seymour, N., additional, Voronkov, M. A., additional, and Wang, L., additional

Published
2019
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49. Connecting X-ray absorption and 21 cm neutral hydrogen absorption in obscured radio AGN

Author

Moss, V., Allison, J., Sadler, E., Urquhart, R., Soria, Roberto, Callingham, J., Curran, S., Musaeva, A., Mahony, E., Glowacki, M., Farrell, S., Bannister, K., Chippendale, A., Edwards, P., Harvey-Smith, L., Heywood, I., Hotan, A., Indermuehle, B., Lenc, E., Marvil, J., McConnell, D., Reynolds, J., Voronkov, M., Wark, R., Whiting, M., Moss, V., Allison, J., Sadler, E., Urquhart, R., Soria, Roberto, Callingham, J., Curran, S., Musaeva, A., Mahony, E., Glowacki, M., Farrell, S., Bannister, K., Chippendale, A., Edwards, P., Harvey-Smith, L., Heywood, I., Hotan, A., Indermuehle, B., Lenc, E., Marvil, J., McConnell, D., Reynolds, J., Voronkov, M., Wark, R., and Whiting, M.

Abstract

Many radio galaxies show the presence of dense and dusty gas near the active nucleus. This can be traced by both 21 cm H I absorption and soft X-ray absorption, offering new insight into the physical nature of the circumnuclear medium of these distant galaxies. To better understand this relationship, we investigate soft X-ray absorption as an indicator for the detection of associated H I absorption, as part of preparation for the First Large Absorption Survey in H I to be undertaken with the Australian Square Kilometre Array Pathfinder (ASKAP). We present the results of our pilot study using the Boolardy Engineering Test Array, a precursor to ASKAP, to search for new absorption detections in radio sources brighter than 1 Jy that also feature soft X-ray absorption. Based on this pilot survey, we detected H I absorption towards the radio source PKS 1657−298 at a redshift of z = 0.42. This source also features the highest X-ray absorption ratio of our pilot sample by a factor of 3, which is consistent with our general findings that X-ray absorption predicates the presence of dense neutral gas. By comparing the X-ray properties of active galactic nuclei with and without detection of H I absorption at radio wavelengths, we find that X-ray hardness ratio and H I absorption optical depth are correlated at a statistical significance of 4.71σ. We conclude by considering the impact of these findings on future radio and X-ray absorption studies.

Published
2017

50. The Detection of an Extremely Bright Fast Radio Burst in a Phased Array Feed Survey

Author

Bannister, KW, Shannon, RM, Macquart, JP, Flynn, C, Edwards, PG, O'Neill, M, Osłowski, S, Bailes, M, Zackay, B, Clarke, N, D'Addario, LR, Dodson, R, Hall, PJ, Jameson, A, Jones, D, Navarro, R, Trinh, JT, Allison, J, Anderson, CS, Bell, M, Chippendale, AP, Collier, JD, Heald, G, Heywood, I, Hotan, AW, Lee-Waddell, K, Madrid, JP, Marvil, J, McConnell, D, Popping, A, Voronkov, MA, Whiting, MT, Allen, GR, Bock, DCJ, Brodrick, DP, Cooray, F, Deboer, DR, Diamond, PJ, Ekers, R, Gough, RG, Hampson, GA, Harvey-Smith, L, Hay, SG, Hayman, DB, Jackson, CA, Johnston, S, Koribalski, BS, McClure-Griffiths, NM, Mirtschin, P, Ng, A, Norris, RP, Pearce, SE, Phillips, CJ, Roxby, DN, Troup, ER, Westmeier, T, Bannister, KW, Shannon, RM, Macquart, JP, Flynn, C, Edwards, PG, O'Neill, M, Osłowski, S, Bailes, M, Zackay, B, Clarke, N, D'Addario, LR, Dodson, R, Hall, PJ, Jameson, A, Jones, D, Navarro, R, Trinh, JT, Allison, J, Anderson, CS, Bell, M, Chippendale, AP, Collier, JD, Heald, G, Heywood, I, Hotan, AW, Lee-Waddell, K, Madrid, JP, Marvil, J, McConnell, D, Popping, A, Voronkov, MA, Whiting, MT, Allen, GR, Bock, DCJ, Brodrick, DP, Cooray, F, Deboer, DR, Diamond, PJ, Ekers, R, Gough, RG, Hampson, GA, Harvey-Smith, L, Hay, SG, Hayman, DB, Jackson, CA, Johnston, S, Koribalski, BS, McClure-Griffiths, NM, Mirtschin, P, Ng, A, Norris, RP, Pearce, SE, Phillips, CJ, Roxby, DN, Troup, ER, and Westmeier, T

Abstract

© 2017. The American Astronomical Society. All rights reserved. We report the detection of an ultra-bright fast radio burst (FRB) from a modest, 3.4-day pilot survey with the Australian Square Kilometre Array Pathfinder. The survey was conducted in a wide-field fly's-eye configuration using the phased-array-feed technology deployed on the array to instantaneously observe an effective area of 160 deg2, and achieve an exposure totaling 13200 deg2 hr . We constrain the position of FRB 170107 to a region in size (90% containment) and its fluence to be 58 ±6 Jy ms. The spectrum of the burst shows a sharp cutoff above 1400 MHz, which could be due to either scintillation or an intrinsic feature of the burst. This confirms the existence of an ultra-bright (∼ Jy ms) population of FRBs.

Published
2017

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