A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz

被引：54

作者：

Bell, M. E. ^{[1
]}

Murphy, T. ^{[1
,2
]}

Kaplan, D. L. ^{[3
]}

Hancock, P. ^{[1
]}

Gaensler, B. M. ^{[1
]}

Banyer, J. ^{[1
]}

Bannister, K. ^{[4
]}

Trott, C. ^{[5
]}

Hurley-Walker, N. ^{[5
]}

Wayth, R. B. ^{[5
]}

Macquart, J-P ^{[5
]}

Arcus, W. ^{[5
]}

Barnes, D. ^{[6
]}

Bernardi, G. ^{[7
,8
]}

Bowman, J. D. ^{[9
]}

Briggs, F. ^{[10
]}

Bunton, J. D. ^{[4
]}

Cappallo, R. J. ^{[11
]}

Corey, B. E. ^{[11
]}

Deshpande, A. ^{[12
]}

deSouza, L. ^{[1
,4
]}

Emrich, D. ^{[5
]}

Goeke, R. ^{[13
]}

Greenhill, L. J. ^{[14
]}

Hazelton, B. J. ^{[15
]}

Herne, D. ^{[5
]}

Hewitt, J. N. ^{[13
]}

Johnston-Hollitt, M. ^{[16
]}

Kasper, J. C. ^{[14
]}

Kincaid, B. B. ^{[11
]}

Koenig, R. ^{[4
]}

Kratzenberg, E. ^{[11
]}

Lonsdale, C. J. ^{[11
]}

Lynch, M. J. ^{[5
]}

McWhirter, S. R. ^{[11
]}

Mitchell, D. A. ^{[17
]}

Morales, M. F. ^{[15
]}

Morgan, E. ^{[13
]}

Oberoi, D. ^{[18
]}

Ord, S. M. ^{[5
]}

Pathikulangara, J. ^{[4
]}

Prabu, T. ^{[12
]}

Remillard, R. A. ^{[13
]}

Rogers, A. E. E. ^{[11
]}

Roshi, A. ^{[12
]}

Salah, J. E. ^{[11
]}

Sault, R. J. ^{[17
]}

Shankar, N. Udaya ^{[12
]}

Srivani, K. S. ^{[12
]}

Stevens, J. ^{[4
,19
]}

机构：

[1] Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia

[2] Univ Sydney, Sch Informat Technol, Sydney, NSW 2006, Australia

[3] Univ Wisconsin, Dept Phys, Milwaukee, WI 53201 USA

[4] CSIRO Astron & Space Sci, Marsfield, NSW 2122, Australia

[5] Curtin Univ Technol, Int Ctr Radio Astron Res, Bentley, WA 6102, Australia

[6] Monash Univ, Monash eRes Ctr, Clayton, Vic 3168, Australia

[7] Rhodes Univ, Dept Phys & Elect, ZA-6140 Grahamstown, South Africa

[8] SKA SA, ZA-7405 Pinelands, South Africa

[9] MIT, Kavli Inst Astrophys & Space Res, Cambridge, MA 02139 USA

[10] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA

[11] Arizona State Univ, Sch Earth & Space Explorat, Tempe, AZ USA

[12] Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia

[13] MIT, Haystack Observ, Westford, MA 01886 USA

[14] Raman Res Inst, Bangalore 560080, Karnataka, India

[15] Univ Washington, Dept Phys, Seattle, WA 98195 USA

[16] Victoria Univ Wellington, Sch Chem & Phys Sci, Wellington 6140, New Zealand

[17] Univ Melbourne, Sch Phys, Parkville, Vic 3010, Australia

[18] Tata Inst Fundamental Res, Natl Ctr Radio Astrophys, Pune 411007, Maharashtra, India

[19] Univ Tasmania, Sch Math & Phys, Hobart, Tas 7001, Australia

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2014年 / 438卷 / 01期

基金：

美国国家科学基金会; 澳大利亚研究理事会;

关键词：

instrumentation: interferometers; techniques: image processing; catalogues; radio continuum: general; EXTRAGALACTIC RADIO-SOURCES; INTERSTELLAR SCINTILLATION; COMPLETE SAMPLES; 318-MHZ VARIABILITY; FIELDS; SKY; CALIBRATION; SPECTRA; GHZ; DISCOVERY;

D O I：

10.1093/mnras/stt2200

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. 51 images were obtained that cover a field of view of 1430 deg(2) centred on Hydra A. The observations were obtained over three days in 2010 March and three days in 2011 April and May. The mean cadence of the observations was 26 min and there was additional temporal information on day and year time-scales. We explore the variability of a sample of 105 low-frequency radio sources within the field. Four bright (S > 6 Jy) candidate variable radio sources were identified that displayed low levels of short time-scale variability (26 min). We conclude that this variability is likely caused by simplifications in the calibration strategy or ionospheric effects. On the time-scale of 1 yr we find two sources that show significant variability. We attribute this variability to either refractive scintillation or intrinsic variability. No radio transients were identified and we place an upper limit on the surface density of sources rho < 7.5 x 10(-5) deg(-2) with flux densities > 5.5 Jy, and characteristic time-scales of both 26 min and 1 yr.

引用

页码：352 / 367

页数：16

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