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X-Ray Burst and Persistent Emission Properties of the Magnetar SGR 1830-0645 in Outburst

Younes, George and Hu, Chin-Ping and Bansal, Karishma and Ray, Paul S. and Pearlman, Aaron B. and Kirsten, Franz and Wadiasingh, Zorawar and Göğüş, Ersin and Baring, Matthew G. and Enoto, Teruaki and Arzoumanian, Zaven and Gendreau, Keith C. and Kouveliotou, Chryssa and Güver, Tolga and Harding, Alice K. and Majid, Walid A. and Blumer, Harsha and Hessels, Jason W. T. and Gawroński, Marcin P. and Bezrukovs, Vladislavs and Orbidans, Arturs (2022) X-Ray Burst and Persistent Emission Properties of the Magnetar SGR 1830-0645 in Outburst. Astrophysical Journal, 924 (2). Art. No. 136. ISSN 0004-637X. doi:10.3847/1538-4357/ac3756.

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We report on NICER X-ray monitoring of the magnetar SGR 1830−0645 covering 223 days following its 2020 October outburst, as well as Chandra and radio observations. We present the most accurate spin ephemerides of the source so far: ν = 0.096008680(2) Hz, ν• = 6.2(1) × 10⁻¹⁴ Hz s⁻¹, and significant second and third frequency derivative terms indicative of nonnegligible timing noise. The phase-averaged 0.8–7 keV spectrum is well fit with a double-blackbody (BB) model throughout the campaign. The BB temperatures remain constant at 0.46 and 1.2 keV. The areas and flux of each component decreased by a factor of 6, initially through a steep decay trend lasting about 46 days, followed by a shallow long-term one. The pulse shape in the same energy range is initially complex, exhibiting three distinct peaks, yet with clear continuous evolution throughout the outburst toward a simpler, single-pulse shape. The rms pulsed fraction is high and increases from about 40% to 50%. We find no dependence of pulse shape or fraction on energy. These results suggest that multiple hot spots, possibly possessing temperature gradients, emerged at outburst onset and shrank as the outburst decayed. We detect 84 faint bursts with NICER, having a strong preference for occurring close to the surface emission pulse maximum—the first time this phenomenon is detected in such a large burst sample. This likely implies a very low altitude for the burst emission region and a triggering mechanism connected to the surface active zone. Finally, our radio observations at several epochs and multiple frequencies reveal no evidence of pulsed or burst-like radio emission.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Younes, George0000-0002-7991-028X
Hu, Chin-Ping0000-0001-8551-2002
Bansal, Karishma0000-0002-7418-7862
Ray, Paul S.0000-0002-5297-5278
Pearlman, Aaron B.0000-0002-8912-0732
Kirsten, Franz0000-0001-6664-8668
Wadiasingh, Zorawar0000-0002-9249-0515
Göğüş, Ersin0000-0002-5274-6790
Baring, Matthew G.0000-0003-4433-1365
Enoto, Teruaki0000-0003-1244-3100
Gendreau, Keith C.0000-0001-7115-2819
Kouveliotou, Chryssa0000-0003-1443-593X
Güver, Tolga0000-0002-3531-9842
Harding, Alice K.0000-0001-6119-859X
Majid, Walid A.0000-0002-4694-4221
Blumer, Harsha0000-0003-4046-884X
Hessels, Jason W. T.0000-0003-2317-1446
Gawroński, Marcin P.0000-0003-4056-4903
Bezrukovs, Vladislavs0000-0003-3655-2280
Additional Information:© 2022. 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. Received 2021 June 15; revised 2021 October 21; accepted 2021 November 6; published 2022 January 19. G.Y. is partly funded through the NASA NICER GI program grant 80NSSC21K0233. M.G.B. acknowledges the generous support of the National Science Foundation through grant AST-1813649. Z.W. acknowledges support from the NASA postdoctoral program. Z.W. acknowledges partial support by NASA under award No. 80GSFC21M0002. F.K. acknowledges support from the Swedish Research Council. A.B.P. is a McGill Space Institute (MSI) Fellow and a Fonds de Recherche du Quebec—Nature et Technologies (FRQNT) postdoctoral fellow. C.-P.H. acknowledges support from the Ministry of Science and Technology in Taiwan through grant MOST 109-2112-M-018-009-MY3. This work is based in part on observations carried out using the 32 m radio telescope operated by the Institute of Astronomy of the Nicolaus Copernicus University in Toruń (Poland) and supported by a Polish Ministry of Science and Higher Education SpUB grant. A portion of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology, and the Caltech campus, under a Research and Technology Development grant through a contract with the National Aeronautics and Space Administration. U.S. government sponsorship is acknowledged. W.A.M. thanks the CDSCC staff and the DSN scheduling team for their rapid response in scheduling and carrying out the radio observations with the DSN.
Funding AgencyGrant Number
NASA Postdoctoral ProgramUNSPECIFIED
Swedish Research CouncilUNSPECIFIED
McGill Space InstituteUNSPECIFIED
Fonds de recherche du Québec - Nature et technologies (FRQNT)UNSPECIFIED
Ministry of Science and Technology (Taipei)109-2112-M-018-009-MY3
Ministry of Science and Higher Education (Poland)UNSPECIFIED
Subject Keywords:Neutron stars; Magnetars; Compact objects; Soft gamma-ray repeaters
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Neutron stars (1108); Magnetars (992); Compact objects (288); Soft gamma-ray repeaters (1471)
Record Number:CaltechAUTHORS:20220119-558563000
Persistent URL:
Official Citation:George Younes et al 2022 ApJ 924 136
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112975
Deposited By: George Porter
Deposited On:19 Jan 2022 22:35
Last Modified:19 Jan 2022 22:35

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