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21 new long-term variables in the GX 339−4 field: two years of MeerKAT monitoring

Driessen, L. N. and Stappers, B. W. and Tremou, E. and Fender, R. P. and Woudt, P. A. and Armstrong, R. and Bloemen, Steven and Groot, P and Heywood, I. and Horesh, A. and van der Horst, A. J. and Koerding, E. and McBride, V. A. and Miller-Jones, J. C. A. and Mooley, K. P. and Rowlinson, A. and Wijers, R. A. M. J. (2022) 21 new long-term variables in the GX 339−4 field: two years of MeerKAT monitoring. Monthly Notices of the Royal Astronomical Society, 512 (4). pp. 5037-5066. ISSN 0035-8711. doi:10.1093/mnras/stac756.

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We present 21 new long-term variable radio sources found commensally in 2 yr of weekly MeerKAT monitoring of the low-mass X-ray binary GX 339−4. The new sources are vary on time-scales of weeks to months and have a variety of light-curve shapes and spectral index properties. Three of the new variable sources are coincident with multiwavelength counterparts; and one of these is coincident with an optical source in deep MeerLICHT images. For most sources, we cannot eliminate refractive scintillation of active galactic nuclei as the cause of the variability. These new variable sources represent 2.2 ± 0.5 per cent of the unresolved sources in the field, which is consistent with the 1–2 per cent variability found in past radio variability surveys. However, we expect to find short-term variable sources in the field and these 21 new long-term variable sources. We present the radio light curves and spectral index variability of the new variable sources, as well as the absolute astrometry and matches to coincident sources at other wavelengths.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Driessen, L. N.0000-0002-4405-3273
Stappers, B. W.0000-0001-9242-7041
Tremou, E.0000-0002-4039-6703
Fender, R. P.0000-0002-5654-2744
Woudt, P. A.0000-0002-6896-1655
Bloemen, Steven0000-0002-6636-921X
Groot, P0000-0002-4488-726X
Heywood, I.0000-0001-6864-5057
Horesh, A.0000-0002-5936-1156
van der Horst, A. J.0000-0001-9149-6707
McBride, V. A.0000-0002-8133-3100
Miller-Jones, J. C. A.0000-0003-3124-2814
Mooley, K. P.0000-0002-2557-5180
Rowlinson, A.0000-0002-1195-7022
Wijers, R. A. M. J.0000-0002-3101-1808
Additional Information:© 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2022 March 14. Received 2022 February 17; in original form 2021 July 11. LND and BWS acknowledge support from the European Research Council (ERC) under the European Union’s Horizon 2020 Framework Programme (grant agreement no. 694745). ET acknowledges financial support from the UnivEarthS Labex program of Université Sorbonne Paris Cité (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02). PAW acknowledges support from the National Research Foundation (NRF) and the University of Cape Town (UCT). AH acknowledges support by the I-CORE Program of the Planning and Budgeting Committee and the Israel Science Foundation, and support by ISF grant 647/18.This research was supported by a grant from the GIF, the German-Israeli Foundation for Scientific Research and Development. AH acknowledges support from GIF. This research was supported by grant no. 2018154 from the United States-Israel Binational Science Foundation (BSF). This work is based on the research supported in part by the National Research Foundation of South Africa (grant numbers 93405 and 119446). We acknowledge use of the Inter-University Institute for Data Intensive Astronomy (IDIA) data intensive research cloud for data processing. IDIA is a South African university partnership involving the University of Cape Town, the University of Pretoria, and the University of the Western Cape. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory (SARAO), which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation, South Africa. We would like to thank the operators, SARAO staff, and ThunderKAT Large Survey Project team. This research made use of ASTROPY,15 a community-developed core PYTHON package for astronomy (Astropy Collaboration 2013, 2018). This research made use of APLPY, an open-source plotting package for PYTHON (Robitaille & Bressert 2012). LND would like to thank Tiaan Bezuidenhout, Manisha Caleb, Fabian Jankowski, Mat Malenta, Vincent Morello, Kaustubh Rajwade, and Mayuresh Surnis for useful and interesting discussions. We would like to thank the referee for their detailed comments that helped us to improve the manuscript. DATA AVAILABILITY. The data underlying this paper are available in Zenodo at The code underlying this paper is available on Zenodo: and
Funding AgencyGrant Number
European Research Council (ERC)694745
Agence Nationale pour la Recherche (ANR)ANR-10-LABX-0023
Agence Nationale pour la Recherche (ANR)ANR-11-IDEX-0005-02
University of Cape TownUNSPECIFIED
I-CORE Program of the Planning and Budgeting CommitteeUNSPECIFIED
Israel Science Foundation647/18
German-Israeli Foundation for Scientific Research and DevelopmentUNSPECIFIED
Binational Science Foundation (USA-Israel)2018154
National Research Foundation (South Africa)93405
National Research Foundation (South Africa)119446
Department of Science and Innovation (South Africa)UNSPECIFIED
Subject Keywords:radio continuum: galaxies, radio continuum: general
Issue or Number:4
Record Number:CaltechAUTHORS:20220525-91690000
Persistent URL:
Official Citation:L N Driessen, B W Stappers, E Tremou, R P Fender, P A Woudt, R Armstrong, S Bloemen, P Groot, I Heywood, A Horesh, A J van der Horst, E Koerding, V A McBride, J C A Miller-Jones, K P Mooley, A Rowlinson, R A M J Wijers, 21 new long-term variables in the GX 339−4 field: two years of MeerKAT monitoring, Monthly Notices of the Royal Astronomical Society, Volume 512, Issue 4, June 2022, Pages 5037–5066,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114925
Deposited By: George Porter
Deposited On:31 May 2022 17:33
Last Modified:31 May 2022 17:33

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