A pilot survey for transients and variables with the Australian Square Kilometre Array Pathfinder

被引：17

作者：

Bhandari, S. ^{[1
,2
,3
]}

Bannister, K. W. ^{[1
]}

Murphy, T. ^{[3
,4
]}

Bell, M. ^{[1
,3
,5
,6
]}

Raja, W. ^{[1
]}

Marvil, J. ^{[1
]}

Hancock, P. J. ^{[3
,7
]}

Whiting, M. ^{[1
]}

Flynn, C. M. ^{[2
,3
]}

Collier, J. D. ^{[1
,8
]}

Kaplan, D. L. ^{[9
]}

Allison, J. R. ^{[4
,10
]}

Anderson, C. ^{[1
,11
]}

Heywood, I ^{[12
,13
]}

Hotan, A. ^{[1
]}

Hunstead, R. ^{[4
]}

Lee-Waddell, K. ^{[1
]}

Madrid, J. P. ^{[1
]}

McConnell, D. ^{[1
]}

Popping, A. ^{[3
,14
]}

Rhee, J. ^{[3
,14
]}

Sadler, E. ^{[3
,4
]}

Voronkov, M. A. ^{[1
]}

机构：

[1] CSIRO Astron & Space Sci, POB 76, Epping, NSW 1710, Australia

[2] Swinburne Univ Technol, Ctr Astrophys & Supercomp, Mail H30,POB 218, Hawthorn, Vic 3122, Australia

[3] ARC Ctr Excellence All Sky Astrophys CAASTRO, Canberra, ACT, Australia

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

[5] Univ Technol Sydney, 15 Broadway, Ultimo, NSW 2007, Australia

[6] Univ Technol, Sch Math & Phys Sci, Sydney, NSW 2007, Australia

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

[8] Western Sydney Univ, Locked Bag 1797, Penrith, NSW 2751, Australia

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

[10] ARC Ctr Excellence All Sky Astrophys 3 Dimens AST, Canberra, ACT, Australia

[11] CSIRO Astron & Space Sci, 26 Dick Perry Ave, Kensington, WA 6152, Australia

[12] Rhodes Univ, Dept Phys & Elect, POB 94, ZA-6140 Grahamstown, South Africa

[13] Univ Oxford, Dept Phys, Astrophys, Keble Rd, Oxford OX1 3RH, England

[14] UWA, ICRAR, 35 Stirling Highway, Crawley, WA 6009, Australia

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2018年 / 478卷 / 02期

基金：

澳大利亚研究理事会;

关键词：

catalogues; ISM: general; galaxies: active; radio continuum: general; INTERSTELLAR SCINTILLATION; RADIO-SOURCES; VARIABILITY; EVENTS;

D O I：

10.1093/mnras/sty1157

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present a pilot search for variable and transient sources at 1.4 GHz with the Australian Square Kilometre Array Pathfinder (ASKAP). The search was performed in a 30 deg(2) area centred on the NGC 7232 galaxy group over eight epochs and observed with a near-daily cadence. The search yielded nine potential variable sources, rejecting the null hypothesis that the flux densities of these sources do not change with 99.9 per cent confidence. These nine sources displayed flux density variations with modulation indices m >= 0.1 above our flux density limit of similar to 1.5mJy. They are identified to be compact active galactic nucleus (AGN)/quasars or galaxies hosting an AGN, whose variability is consistent with refractive interstellar scintillation. We also detect a highly variable source with modulation index m>0.5 over a time interval of a decade between the SydneyUniversity Molonglo Sky Survey (SUMSS) and our latest ASKAP observations. We find the source to be consistent with the properties of long-term variability of a quasar. No transients were detected on time-scales of days and we place an upper limit rho(t) < 0.01 deg(-2) with 95 per cent confidence for non-detections on near-daily time-scales. The future VAST-Wide survey with 36-ASKAP dishes will probe the transient phase space with similar cadence to our pilot survey, but better sensitivity, and will detect and monitor rarer brighter events.

引用

页码：1784 / 1794

页数：11