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NICER View of the 2020 Burst Storm and Persistent Emission of SGR 1935+2154

Younes, George and Güver, Tolga and Kouveliotou, Chryssa and Baring, Matthew G. and Hu, Chin-Ping and Wadiasingh, Zorawar and Begiçarslan, Beste and Enoto, Teruaki and Göğüş, Ersin and Lin, Lin and Harding, Alice K. and van der Horst, Alexander J. and Majid, Walid A. and Guillot, Sebastien and Malacaria, Christian (2020) NICER View of the 2020 Burst Storm and Persistent Emission of SGR 1935+2154. Astrophysical Journal Letters, 904 (2). Art. No. L21. ISSN 2041-8213.

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We report on NICER observations of the magnetar SGR 1935+2154, covering its 2020 burst storm and long-term persistent emission evolution up to ~90 days postoutburst. During the first 1120 s taken on April 28 00:40:58 UTC, we detect over 217 bursts, corresponding to a burst rate of >0.2 bursts s⁻¹. Three hours later, the rate was 0.008 bursts s⁻¹, remaining at a comparatively low level thereafter. The T 90 burst duration distribution peaks at 840 ms; the distribution of waiting times to the next burst is fit with a lognormal with an average of 2.1 s. The 1–10 keV burst spectra are well fit by a blackbody, with an average temperature and area of kT = 1.7 keV and R² = 53 km². The differential burst fluence distribution over ~3 orders of magnitude is well modeled with a power-law form dN/dF ∝ F_(−1.5)^(±0.1). The source persistent emission pulse profile is double-peaked hours after the burst storm. We find that the burst peak arrival times follow a uniform distribution in pulse phase, though the fast radio burst associated with the source aligns in phase with the brighter peak. We measure the source spin-down from heavy-cadence observations covering days 21–39 postoutburst, ν˙=−3.72(3)×10⁻¹² Hz s ⁻¹, a factor of 2.7 larger than the value measured after the 2014 outburst. Finally, the persistent emission flux and blackbody temperature decrease rapidly in the early stages of the outburst, reaching quiescence 40 days later, while the size of the emitting area remains unchanged.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Younes, George0000-0002-7991-028X
Güver, Tolga0000-0002-3531-9842
Kouveliotou, Chryssa0000-0003-1443-593X
Baring, Matthew G.0000-0003-4433-1365
Hu, Chin-Ping0000-0001-8551-2002
Wadiasingh, Zorawar0000-0002-9249-0515
Begiçarslan, Beste0000-0001-5072-8444
Enoto, Teruaki0000-0003-1244-3100
Göğüş, Ersin0000-0002-5274-6790
Lin, Lin0000-0002-0633-5325
Harding, Alice K.0000-0001-6119-859X
van der Horst, Alexander J.0000-0001-9149-6707
Majid, Walid A.0000-0002-4694-4221
Guillot, Sebastien0000-0002-6449-106X
Malacaria, Christian0000-0002-0380-0041
Alternate Title:The NICER View of the 2020 Burst Storm and Persistent Emission of SGR 1935+2154
Additional Information:© 2020. The American Astronomical Society. Received 2020 September 16; revised 2020 October 27; accepted 2020 November 10; published 2020 November 27. A portion of this work was supported by NASA through the NICER mission and the Astrophysics Explorers Program. This research has made use of data and 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. The authors are grateful to the referee for constructive comments that improved the quality of the manuscript. G.Y. sincerely thanks Jason Hessels for his request to perform more detailed late-time temporal analysis, which proved highly fruitful. G.Y. acknowledges support from NASA under NICER Guest Observer cycle 1 program 2098, grant No. 80NSSC19K1452. M.G.B. acknowledges the generous support of the National Science Foundation through grant AST-1813649. Z.W. is supported by the NASA postdoctoral program. C.K. acknowledges support from NASA under grant 80NSSC17K0761. This work has made use of the NASA Astrophysics Data System.
Funding AgencyGrant Number
NASA Postdoctoral ProgramUNSPECIFIED
Subject Keywords:Neutron stars ; Magnetars ; Soft gamma-ray repeaters
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Neutron stars (1108); Magnetars (992); Soft gamma-ray repeaters (1471)
Record Number:CaltechAUTHORS:20201204-110357020
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Official Citation:George Younes et al 2020 ApJL 904 L21
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106913
Deposited By: George Porter
Deposited On:04 Dec 2020 23:17
Last Modified:04 Dec 2020 23:17

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