We report on X-ray (NICER/NuSTAR/MAXI/Swift) and radio (MeerKAT) timing and spectroscopic analysis from a 3 month monitoring campaign in 2022 of a high-intensity outburst of the dipping neutron star low-mass X-ray binary 1A 1744−361. The 0.5–6.8 keV NICER X-ray hardness–intensity and color–color diagrams of the observations throughout the outburst suggest that 1A 1744−361 spent most of its outburst in an atoll-state, but we show that the source exhibited Z-state-like properties at the peak of the outburst, similar to a small sample of other atoll-state sources. A timing analysis with NICER data revealed several instances of an ≈8 Hz quasiperiodic oscillation (QPO; fractional rms amplitudes of ∼5%) around the peak of the outburst, the first from this source, which we connect to the normal branch QPOs seen in the Z-state. Our observations of 1A 1744−361 are fully consistent with the idea of the mass accretion rate being the main distinguishing parameter between atoll- and Z-states. Radio monitoring data by MeerKAT suggests that the source was at its radio-brightest during the outburst peak, and that the source transitioned from the "island" spectral state to the "banana" state within ∼3 days of the outburst onset, launching transient jet ejecta. The observations present the strongest evidence for radio flaring, including jet ejecta, during the island-to-banana spectral state transition at low accretion rates (atoll-state). The source also exhibited Fe xxv, Fe xxvi Kα, and Kβ X-ray absorption lines, whose origins likely lie in an accretion disk atmosphere.
X-Ray and Radio Monitoring of the Neutron Star Low-mass X-Ray Binary 1A 1744-361: Quasiperiodic Oscillations, Transient Ejections, and a Disk Atmosphere
Creators
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Ng, Mason
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Hughes, Andrew K.
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Homan, Jeroen
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Miller, Jon M.
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Pike, Sean N.
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Altamirano, Diego
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Bult, Peter
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Chakrabarty, Deepto
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Buisson, D. J. K.
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Coughenour, Benjamin M.
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Fender, Rob
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Guillot, Sebastien
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Güver, Tolga
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Jaisawal, Gaurava K.
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Jaodand, Amruta D.
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Malacaria, Christian
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Miller-Jones, James C. A.
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Sanna, Andrea
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Sivakoff, Gregory R.
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Strohmayer, Tod E.
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Tomsick, John A.
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van den Eijnden, Jakob
Abstract
Copyright and License
© 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
We thank the anonymous referee for comments that improved the clarity of the presentation and description of the results. We thank Thomas Dauser and Javier Garcia for their persistence to get relxill to be able to compile on MacOS systems with the M1 chip. M.N. also thanks Megan Masterson and Jingyi Wang for discussions about aperiodic timing and NICERDAS tools. M.N. was supported in part by NASA through the NICER Guest Observer Program. A.K.H. and G.R.S. are supported by NSERC Discovery Grant RGPIN-2021-0400. J.v.d.E. acknowledges a Warwick Astrophysics prize post-doctoral fellowship made possible thanks to a generous philanthropic donation. NICER work at NRL is also supported by NASA. This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory. This research has made use of MAXI data provided by RIKEN, JAXA, and the MAXI team. This research has made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. Data analysis was performed using the NuSTAR Data Analysis Software (NuSTARDAS), jointly developed by the ASI Science Data Center (SSDC, Italy) and the California Institute of Technology (USA). We acknowledge the use of public data from the Swift data archive. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation.
A.K.H. and G.R.S. respectfully acknowledge that they perform the majority of their research from Treaty 6 territory, a traditional gathering place for diverse Indigenous peoples, including the Cree, Blackfoot, Métis, Nakota Sioux, Iroquois, Dene, Ojibway/Saulteaux/Anishinaabe, Inuit, and many others whose histories, languages, and cultures continue to influence our vibrant community.
Facilities
NICER - , MAXI - JAXA Monitor of All-sky X-ray Image experiment, NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission, Swift - Swift Gamma-Ray Burst Mission, MeerKAT -
Software References
Astropy (Astropy Collaboration et al. 2013, 2018), NumPy and SciPy (Virtanen et al. 2020), Matplotlib (Hunter 2007), IPython (Perez & Granger 2007), tqdm (da Costa-Luis et al. 2022), HEASoft 6.31.1 25 (NASA High Energy Astrophysics Science Archive Research Center (HEASARC), 2014)
Files
Ng_2024_ApJ_966_232.pdf
Additional details
Identifiers
- ISSN
- 1538-4357
Funding
- Natural Sciences and Engineering Research Council
- RGPIN-2021-0400
- University of Warwick
- National Aeronautics and Space Administration