NICER View of the 2020 Burst Storm and Persistent Emission of SGR 1935+2154
Abstract
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.
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.Errata
George Younes et al 2021 ApJL 913 L17Attached Files
Published - Younes_2020_ApJL_904_L21.pdf
Accepted Version - 2009.07886.pdf
Erratum - Younes_2021_ApJL_913_L17.pdf
Files
Additional details
- Alternative title
- The NICER View of the 2020 Burst Storm and Persistent Emission of SGR 1935+2154
- Eprint ID
- 106913
- Resolver ID
- CaltechAUTHORS:20201204-110357020
- 80NSSC19K1452
- NASA
- AST-1813649
- NSF
- NASA Postdoctoral Program
- 80NSSC17K0761
- NASA
- Created
-
2020-12-04Created from EPrint's datestamp field
- Updated
-
2021-05-26Created from EPrint's last_modified field