A search for long-time-scale, low-frequency radio transients

Tara Murphy, David L. Kaplan, Steve Croft, Christene Lynch, J. R. R. Callingham, Keith Bannister, Martin E. Bell, Natasha Hurley-Walker, Paul Hancock, Jack Line, Antonia Rowlinson, Emil Lenc, H.T. Intema, P. Jagannathan, Ronald D. Ekers, Steven Tingay, Fang Yuan, Christian Wolf, Christopher A. Onken, K. S. S. Dwarakanath & 13 others Bi-Qing For, B. M. M. Gaensler, L. Hindson, M. Johnston-Hollitt, A. D. Kapinska, B. Mckinley, J. Morgan, A.R. Offringa, P. Procopio, L. Staveley-Smith, R. B. B. Wayth, C. Wu, Q. Zheng

Research output: Contribution to journalArticle

Abstract

We present a search for transient and highly variable sources at low radio frequencies (150200 MHz) that explores long time-scales of 1-3 yr. We conducted this search by comparing the TIFR GMRT Sky Survey Alternative Data Release 1 (TGSS ADR1) and the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey catalogues. To account for the different completeness thresholds in the individual surveys, we searched for compact GLEAM sources above a flux density limit of 100 mJy that were not present in the TGSS ADR1; and also for compact TGSS ADR1 sources above a flux density limit of 200 mJy that had no counterpart in GLEAM. From a total sample of 234 333 GLEAM sources and 275 612 TGSS ADR1 sources in the overlap region between the two surveys, there were 99 658 GLEAM sources and 38 978 TGSS ADR sources that passed our flux density cut-off and compactness criteria. Analysis of these sources resulted in three candidate transient sources. Further analysis ruled out two candidates as imaging artefacts. We analyse the third candidate and show it is likely to be real, with a flux density of 182 +/- 26 mJy at 147.5 MHz. This gives a transient surface density of rho = (6.2 +/- 6) x 10(-5) deg(-2). We present initial follow-up observations and discuss possible causes for this candidate. The small number of spurious sources from this search demonstrates the high reliability of these two new low-frequency radio catalogues.

Original languageEnglish
Pages (from-to)1944-1953
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume466
Issue number2
DOIs
Publication statusPublished - 11 Apr 2017

Cite this

Murphy, T., Kaplan, D. L., Croft, S., Lynch, C., Callingham, J. R. R., Bannister, K., ... Zheng, Q. (2017). A search for long-time-scale, low-frequency radio transients. Monthly Notices of the Royal Astronomical Society, 466(2), 1944-1953. https://doi.org/10.1093/mnras/stw3087
Murphy, Tara ; Kaplan, David L. ; Croft, Steve ; Lynch, Christene ; Callingham, J. R. R. ; Bannister, Keith ; Bell, Martin E. ; Hurley-Walker, Natasha ; Hancock, Paul ; Line, Jack ; Rowlinson, Antonia ; Lenc, Emil ; Intema, H.T. ; Jagannathan, P. ; Ekers, Ronald D. ; Tingay, Steven ; Yuan, Fang ; Wolf, Christian ; Onken, Christopher A. ; Dwarakanath, K. S. S. ; For, Bi-Qing ; Gaensler, B. M. M. ; Hindson, L. ; Johnston-Hollitt, M. ; Kapinska, A. D. ; Mckinley, B. ; Morgan, J. ; Offringa, A.R. ; Procopio, P. ; Staveley-Smith, L. ; Wayth, R. B. B. ; Wu, C. ; Zheng, Q. / A search for long-time-scale, low-frequency radio transients. In: Monthly Notices of the Royal Astronomical Society. 2017 ; Vol. 466, No. 2. pp. 1944-1953.
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Murphy, T, Kaplan, DL, Croft, S, Lynch, C, Callingham, JRR, Bannister, K, Bell, ME, Hurley-Walker, N, Hancock, P, Line, J, Rowlinson, A, Lenc, E, Intema, HT, Jagannathan, P, Ekers, RD, Tingay, S, Yuan, F, Wolf, C, Onken, CA, Dwarakanath, KSS, For, B-Q, Gaensler, BMM, Hindson, L, Johnston-Hollitt, M, Kapinska, AD, Mckinley, B, Morgan, J, Offringa, AR, Procopio, P, Staveley-Smith, L, Wayth, RBB, Wu, C & Zheng, Q 2017, 'A search for long-time-scale, low-frequency radio transients' Monthly Notices of the Royal Astronomical Society, vol. 466, no. 2, pp. 1944-1953. https://doi.org/10.1093/mnras/stw3087

A search for long-time-scale, low-frequency radio transients. / Murphy, Tara; Kaplan, David L.; Croft, Steve; Lynch, Christene; Callingham, J. R. R.; Bannister, Keith; Bell, Martin E.; Hurley-Walker, Natasha; Hancock, Paul; Line, Jack; Rowlinson, Antonia; Lenc, Emil; Intema, H.T.; Jagannathan, P.; Ekers, Ronald D.; Tingay, Steven; Yuan, Fang; Wolf, Christian; Onken, Christopher A.; Dwarakanath, K. S. S.; For, Bi-Qing; Gaensler, B. M. M.; Hindson, L.; Johnston-Hollitt, M.; Kapinska, A. D.; Mckinley, B.; Morgan, J.; Offringa, A.R.; Procopio, P.; Staveley-Smith, L.; Wayth, R. B. B.; Wu, C.; Zheng, Q.

In: Monthly Notices of the Royal Astronomical Society, Vol. 466, No. 2, 11.04.2017, p. 1944-1953.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A search for long-time-scale, low-frequency radio transients

AU - Murphy, Tara

AU - Kaplan, David L.

AU - Croft, Steve

AU - Lynch, Christene

AU - Callingham, J. R. R.

AU - Bannister, Keith

AU - Bell, Martin E.

AU - Hurley-Walker, Natasha

AU - Hancock, Paul

AU - Line, Jack

AU - Rowlinson, Antonia

AU - Lenc, Emil

AU - Intema, H.T.

AU - Jagannathan, P.

AU - Ekers, Ronald D.

AU - Tingay, Steven

AU - Yuan, Fang

AU - Wolf, Christian

AU - Onken, Christopher A.

AU - Dwarakanath, K. S. S.

AU - For, Bi-Qing

AU - Gaensler, B. M. M.

AU - Hindson, L.

AU - Johnston-Hollitt, M.

AU - Kapinska, A. D.

AU - Mckinley, B.

AU - Morgan, J.

AU - Offringa, A.R.

AU - Procopio, P.

AU - Staveley-Smith, L.

AU - Wayth, R. B. B.

AU - Wu, C.

AU - Zheng, Q.

PY - 2017/4/11

Y1 - 2017/4/11

N2 - We present a search for transient and highly variable sources at low radio frequencies (150200 MHz) that explores long time-scales of 1-3 yr. We conducted this search by comparing the TIFR GMRT Sky Survey Alternative Data Release 1 (TGSS ADR1) and the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey catalogues. To account for the different completeness thresholds in the individual surveys, we searched for compact GLEAM sources above a flux density limit of 100 mJy that were not present in the TGSS ADR1; and also for compact TGSS ADR1 sources above a flux density limit of 200 mJy that had no counterpart in GLEAM. From a total sample of 234 333 GLEAM sources and 275 612 TGSS ADR1 sources in the overlap region between the two surveys, there were 99 658 GLEAM sources and 38 978 TGSS ADR sources that passed our flux density cut-off and compactness criteria. Analysis of these sources resulted in three candidate transient sources. Further analysis ruled out two candidates as imaging artefacts. We analyse the third candidate and show it is likely to be real, with a flux density of 182 +/- 26 mJy at 147.5 MHz. This gives a transient surface density of rho = (6.2 +/- 6) x 10(-5) deg(-2). We present initial follow-up observations and discuss possible causes for this candidate. The small number of spurious sources from this search demonstrates the high reliability of these two new low-frequency radio catalogues.

AB - We present a search for transient and highly variable sources at low radio frequencies (150200 MHz) that explores long time-scales of 1-3 yr. We conducted this search by comparing the TIFR GMRT Sky Survey Alternative Data Release 1 (TGSS ADR1) and the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey catalogues. To account for the different completeness thresholds in the individual surveys, we searched for compact GLEAM sources above a flux density limit of 100 mJy that were not present in the TGSS ADR1; and also for compact TGSS ADR1 sources above a flux density limit of 200 mJy that had no counterpart in GLEAM. From a total sample of 234 333 GLEAM sources and 275 612 TGSS ADR1 sources in the overlap region between the two surveys, there were 99 658 GLEAM sources and 38 978 TGSS ADR sources that passed our flux density cut-off and compactness criteria. Analysis of these sources resulted in three candidate transient sources. Further analysis ruled out two candidates as imaging artefacts. We analyse the third candidate and show it is likely to be real, with a flux density of 182 +/- 26 mJy at 147.5 MHz. This gives a transient surface density of rho = (6.2 +/- 6) x 10(-5) deg(-2). We present initial follow-up observations and discuss possible causes for this candidate. The small number of spurious sources from this search demonstrates the high reliability of these two new low-frequency radio catalogues.

KW - catalogues

KW - galaxies: active

KW - radio continuum: general

KW - MURCHISON WIDEFIELD ARRAY

KW - ACTIVE GALACTIC NUCLEI

KW - SKY SURVEY

KW - REDSHIFT SURVEY

KW - MAGNETIC-FIELD

KW - SOUTHERN SKY

KW - FLARE STARS

KW - LOFAR

KW - I.

KW - TELESCOPE

U2 - 10.1093/mnras/stw3087

DO - 10.1093/mnras/stw3087

M3 - Article

VL - 466

SP - 1944

EP - 1953

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

ER -

Murphy T, Kaplan DL, Croft S, Lynch C, Callingham JRR, Bannister K et al. A search for long-time-scale, low-frequency radio transients. Monthly Notices of the Royal Astronomical Society. 2017 Apr 11;466(2):1944-1953. https://doi.org/10.1093/mnras/stw3087